First-Principles Study on the Interplay of Strain and State-of-Charge with Li-Ion Diffusion in the Battery Cathode Material LiCoO₂

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1. 1

   Qin, Z.; Zhang, Y.; Luo, W.; Zhang, T.; Wang, T.; Ni, L.; Wang, H.; Zhang, N.; Liu, X.; Zhou, J.; Chen, G. A Universal Molten Salt Method for Direct Upcycling of Spent Ni-Rich Cathode towards Single-Crystalline Li-Rich Cathode. Angew. Chem., Int. Ed. 2023, 62 (25), e202218672  DOI: 10.1002/ange.202218672

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   A Universal Molten Salt Method for Direct Upcycling of Spent Ni-rich Cathode towards Single-crystalline Li-rich Cathode

   Qin, Zuoyu; Zhang, Ying; Luo, Wuqing; Zhang, Tao; Wang, Tao; Ni, Lianshan; Wang, Haoji; Zhang, Ning; Liu, Xiaohe; Zhou, Jiang; Chen, Gen

   Angewandte Chemie, International Edition (2023), 62 (25), e202218672CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)

   With ever-increasing pursuit for high-value output in recycling spent lithium-ion batteries (LIBs), traditional recycling methods of cathodes tend to be obsolete because of the complicated procedures. Herein, we first upcycle spent polycrystal LiNi0.88Co0.095Al0.025O2 (S-NCA) to high value-added single-cryst. and Li-rich cathode materials through a simple but feasible LiOH-Na2SO4 eutectic molten salt strategy. The in situ X-ray diffraction technique and a series of paratactic expts. record the evolution process of upcycling and prove that excessive Li occupies the transition metal (TM) layers. Beneficial from the single-cryst. and Li-rich nature, the regenerated NCA (R-NCA) exhibits remarkably enhanced electrochem. performances in terms of long-term cyclability, high-rate performance and low polarization. This approach can also be successfully extended to other cathode materials e.g., LiNixCoyMnzO2 (NCM) and mixed spent NCAs with varied degree of Li loss.
2. 2

   Ugata, Y.; Yukishita, K.; Kazahaya, N.; Takahashi, S.; Yabuuchi, N. Nonflammable Fluorinated Ester-Based Electrolytes for Safe and High-Energy Batteries with LiCoO₂. Chem. Mater. 2023, 35 (9), 3686– 3693,  DOI: 10.1021/acs.chemmater.3c00374

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   Nonflammable Fluorinated Ester-Based Electrolytes for Safe and High-Energy Batteries with LiCoO2

   Ugata, Yosuke; Yukishita, Kazuki; Kazahaya, Natsuho; Takahashi, Shingo; Yabuuchi, Naoaki

   Chemistry of Materials (2023), 35 (9), 3686-3693CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)

   To further improve the energy d. and safety of Li-ion batteries (LIBs), multifunctional electrolyte solvents are needed to replace conventional carbonate solvents. In this study, a nonflammable fluorinated ester, Me 3,3,3-trifluoropropionate (MTFP), is evaluated as an electrolyte solvent for high-voltage Li batteries with the LiCoO2 pos. electrode. A Li/LiCoO2 cell with an MTFP-based electrolyte exhibits superior capacity retention compared with a cell with a conventional carbonate-based electrolyte with a cutoff voltage of 4.5 V. Moreover, the LiCoO2 composite electrode with sodium CM-cellulose and styrene-butadiene rubber as binders, instead of the commonly used poly(vinylidene fluoride), can be cycled in the MTFP-based electrolyte without capacity loss or increase in polarization under high-voltage operation. The low-temp. performance and thermal stability of the LiCoO2 electrode are also improved by using the MTFP-based electrolyte. The anal. by XPS of the LiCoO2 electrode cycled in the MTFP-based electrolyte suggests that a thin and uniform passivation layer is formed on the electrode surface, resulting in excellent cyclability and thermal stability for LiCoO2. The insights related to nonflammable electrolytes contribute to the development of high-energy LIBs without sacrificing safety.
3. 3

   Goodenough, J. B.; Kim, Y. Challenges for Rechargeable Li Batteries. Chem. Mater. 2010, 22 (3), 587– 603,  DOI: 10.1021/cm901452z

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   Challenges for Rechargeable Li Batteries

   Goodenough, John B.; Kim, Youngsik

   Chemistry of Materials (2010), 22 (3), 587-603CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)

   A review of challenges for further development of Li rechargeable batteries for elec. vehicles. Most important is safety, which requires development of a nonflammable electrolyte with either a larger window between its LUMO and HOMO or a constituent (or additive) that can develop rapidly a solid/electrolyte interface (SEI) layer to prevent plating of Li on a carbon anode during a fast charge of the battery. A high Li+-ion cond. (σLi > 10-4 S/cm) in the electrolyte and across the electrode/electrolyte interface is needed for a power battery. Important also is an increase in the d. of the stored energy, which is the product of the voltage and capacity of reversible Li insertion/extn. into/from the electrodes. It will be difficult to design a better anode than carbon, but carbon requires formation of an SEI layer, which involves an irreversible capacity loss. The design of a cathode composed of environmentally benign, low-cost materials that has its electrochem. potential μC well-matched to the HOMO of the electrolyte and allows access to two Li atoms per transition-metal cation would increase the energy d., but it is a daunting challenge. Two redox couples can be accessed where the cation redox couples are pinned at the top of the O 2p bands, but to take advantage of this possibility, it must be realized in a framework structure that can accept more than one Li atom per transition-metal cation. Moreover, such a situation represents an intrinsic voltage limit of the cathode, and matching this limit to the HOMO of the electrolyte requires the ability to tune the intrinsic voltage limit. Finally, the chem. compatibility in the battery must allow a long service life.
4. 4

   Fergus, J. W. Recent Developments in Cathode Materials for Lithium Ion Batteries. J. Power Sources 2010, 195 (4), 939– 954,  DOI: 10.1016/j.jpowsour.2009.08.089

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   Recent developments in cathode materials for lithium ion batteries

   Fergus, Jeffrey W.

   Journal of Power Sources (2010), 195 (4), 939-954CODEN: JPSODZ; ISSN:0378-7753. (Elsevier B.V.)

   A review. One of the challenges for improving the performance of lithium ion batteries to meet increasingly demanding requirements for energy storage is the development of suitable cathode materials. Cathode materials must be able to accept and release lithium ions repeatedly (for recharging) and quickly (for high current). Transition metal oxides based on the α-NaFeO2, spinel and olivine structures have shown promise, but improvements are needed to reduce cost and extend effective lifetime. In this paper, recent developments in cathode materials for lithium ion batteries are reviewed. This includes comparison of the performance characteristics of the promising cathode materials and approaches for improving their performances.
5. 5

   Zhou, J.; Notten, P. H. L. Studies on the Degradation of Li-Ion Batteries by the Use of Microreference Electrodes. J. Power Sources 2008, 177 (2), 553– 560,  DOI: 10.1016/j.jpowsour.2007.11.032

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   Studies on the degradation of Li-ion batteries by the use of microreference electrodes

   Zhou, J.; Notten, P. H. L.

   Journal of Power Sources (2008), 177 (2), 553-560CODEN: JPSODZ; ISSN:0378-7753. (Elsevier B.V.)

   Li-ion batteries made by the Lithylene technol. were investigated after extensive cycling for a mechanistic understanding of the capacity fade phenomena. The batteries cycled 500 times at 0.5C were found to lose 13% of their original capacity, which was solely due to the loss of active materials. The anode maintained its capacity to contain Li+ ions from the cathode. The loss of cathode materials was attributed to formation and thickening of the surface layer and structure disorder evidenced by x-ray diffraction measurements. In situ impedance measurements revealed that the cathode was also responsible for the impedance rise upon cycling. The charge transfer resistance was found to be the most influential factor in the battery impedance, which increased exponentially during cycling. This increase was not due to the decrease of cathode surface area but resulted from growth of the surface layer.
6. 6

   Tan, Z.; Li, Y.; Xi, X.; Jiang, S.; Li, X.; Shen, X.; Zhang, P.; He, Z.; Zheng, J. A Novelty Strategy Induced Pinning Effect and Defect Structure in Ni-Rich Layered Cathodes towards Boosting Its Electrochemical Performance. Journal of Energy Chemistry 2022, 72, 570– 580,  DOI: 10.1016/j.jechem.2022.05.037

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   A novelty strategy induced pinning effect and defect structure in Ni-rich layered cathodes towards boosting its electrochemical performance

   Tan, Zhouliang; Li, Yunjiao; Xi, Xiaoming; Jiang, Shijie; Li, Xiaohui; Shen, Xingjie; Zhang, Panpan; He, Zhenjiang; Zheng, Junchao

   Journal of Energy Chemistry (2022), 72 (), 570-580CODEN: JECOFG; ISSN:2095-4956. (Science Press)

   Layered Ni-rich transition metal oxide is treated as the most promising alternative cathode due to their high-capacity and flexible compn. However, the severe lattice strain and slow Li-ion migration kinetics severely restrict their practical application. Herein, a novelty strategy induced pinning effect and defect structure in layered Ni-rich transition metal oxide cathodes is proposed via a facile cation(iron ion)/anion(polyanion) co-doping method. Subsequently, the effects of pinning effect and defect structure on element valence state, crystal structure, morphol., lattice strain, and electrochem. performance during lithiation/delithiation are systematically explored. The detailed characterizations (soft X-ray absorption spectroscopy (sXAS), in-situ X-ray diffraction (XRD), etc.) and d. functional theory (DFT) calcn. demonstrate that the pinning effects built-in LiNi0.9Co0.05Mn0.05O2 materials by the dual-site occupation of iron ions on lithium and transition metal sites effectively alleviate the abrupt lattice strain caused by an unfavorable phase transition and the subsequent induction of defect structures in the Li layer can greatly reduce the lithium-ion diffusion barrier. Therefore, the modified LiNi0.9Co0.05Mn0.05O2 exhibits a high-capacity of 206.5 mAh g-1 and remarkably enhanced capacity retention of 93.9% after 100 cycles, far superior to ∼14.1% of the pristine cathodes. Besides, an excellent discharge capacity of 180.1 mAh g-1 at 10 C rate is maintained, illustrating its remarkable rate capability. This work reports a pinning effect and defect engineering method to suppress the lattice strain and alleviate lithium-ion kinetic barriers in the Ni-rich layered cathodes, providing a roadmap for understanding the fundamental mechanism of an intrinsic activity modulation and structural design of layered cathode materials.
7. 7

   Tokranov, A.; Sheldon, B. W.; Lu, P.; Xiao, X.; Mukhopadhyay, A. The Origin of Stress in the Solid Electrolyte Interphase on Carbon Electrodes for Li Ion Batteries. J. Electrochem. Soc. 2014, 161 (1), A58,  DOI: 10.1149/2.009401jes

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   The origin of stress in the solid electrolyte interphase on carbon electrodes for Li ion batteries

   Tokranov, A.; Sheldon, B. W.; Lu, P.; Xiao, X.; Mukhopadhyay, A.

   Journal of the Electrochemical Society (2014), 161 (1), A58-A65CODEN: JESOAN; ISSN:0013-4651. (Electrochemical Society)

   This paper focuses on stress generation during the initial stages of the Solid Electrolyte Interphase (SEI) formation on graphite electrodes. C-axis oriented graphitic carbon, grown via chem. vapor deposition (CVD), is used as a model system for this study, to enable reliable characterization using Secondary Ion Mass Spectroscopy (SIMS) and X-ray Photo-electron Spectroscopy (XPS). The SEI formation was also probed by recording the stress development in-situ during const. voltage holds above the lithium intercalation threshold, using a Multi-beam Optical Stress Sensor (MOSS). This provides direct correlations between the potential, current and stress. SIMS and XPS anal. of the surface chem. of the cycled samples show high carbon content near the surface. Cross-sectional TEM indicates that these surface layers are predominantly amorphous. Based on the evidence and anal., the stress in this amorphous layer is believed to play an important role in stabilizing the inorg. SEI layer. An understanding of this interlayer can be used to design a more mech. stable SEI layer, and is also potentially relevant to other electrode materials which show much higher vol. expansions.
8. 8

   Gao, B.; Jalem, R.; Ma, Y.; Tateyama, Y. Li⁺ Transport Mechanism at the Heterogeneous Cathode/Solid Electrolyte Interface in an All-Solid-State Battery via the First-Principles Structure Prediction Scheme. Chem. Mater. 2020, 32 (1), 85– 96,  DOI: 10.1021/acs.chemmater.9b02311

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   Li+ Transport Mechanism at the Heterogeneous Cathode/Solid Electrolyte Interface in an All-Solid-State Battery via the First-Principles Structure Prediction Scheme

   Gao, Bo; Jalem, Randy; Ma, Yanming; Tateyama, Yoshitaka

   Chemistry of Materials (2020), 32 (1), 85-96CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)

   High interfacial resistance between a cathode and solid electrolyte (SE) has been a long-standing problem for all-solid-state batteries (ASSBs). Though thermodn. approaches suggested possible phase transformations at the interfaces, direct analyses of the ionic and electronic states at the solid/solid interfaces are still crucial. Here, newly constructed scheme is used for predicting heterogeneous interface structures via the swarm-intelligence-based crystal structure anal. by particle swarm optimization method, combined with d. functional theory calcns., and systematically investigated the mechanism of Li-ion (Li+) transport at the interface in LiCoO2 cathode/β-Li3PS4 SE, a representative ASSB system. The sampled favorable interface structures indicate that the interfacial reaction layer is formed with both mixing of Co and P cations and mixing of O and S anions. The calcd. site-dependent Li chem. potentials μLi(r) and potential energy surfaces for Li+ migration across the interfaces reveal that interfacial Li+ sites with higher μLi(r) values cause dynamic Li+ depletion with the interfacial electron transfer in the initial stage of charging. The Li+-depleted space can allow oxidative decompn. of SE materials. These pieces of evidence theor. confirm the primary origin of the obsd. interfacial resistance in ASSBs and the mechanism of the resistance decrease obsd. with oxide buffer layers (e.g., LiNbO3) and oxide SE. The present study also provides a perspective for the structure sampling of disordered heterogeneous solid/solid interfaces on the at. scale.
9. 9

   Mukhopadhyay, A.; Tokranov, A.; Xiao, X.; Sheldon, B. W. Stress Development Due to Surface Processes in Graphite Electrodes for Li-Ion Batteries: A First Report. Electrochim. Acta 2012, 66, 28– 37,  DOI: 10.1016/j.electacta.2012.01.058

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   Stress development due to surface processes in graphite electrodes for Li-ion batteries: A first report

   Mukhopadhyay, Amartya; Tokranov, Anton; Xiao, Xingcheng; Sheldon, Brian W.

   Electrochimica Acta (2012), 66 (), 28-37CODEN: ELCAAV; ISSN:0013-4686. (Elsevier Ltd.)

   The authors report for the 1st time the development of irreversible compressive stresses in graphitic C electrodes during cycling in a Li-ion battery. The CVD grown c-axis oriented graphitic C thin film electrodes show that significant irreversible stresses develop in the 1st cycle, and then decrease with increasing no. of cycles. The net irreversible compressive stress is roughly a factor of 4 higher than the actual Li-intercalation induced reversible compressive stress. A major fraction of the irreversible stress developed at potentials higher than the Li-intercalation potential, starting from ∼1.1 V and increasing in intensity from ∼0.75 V Also, the variation of the irreversible stress with no. of cycles follows very closely the variation of the irreversible capacity with cycle no. Measurements on C films with different thicknesses show that the irreversible stress is primarily a surface phenomenon. These stresses were also largely absent in films coated with a thin (0.5 nm) Al2O3 layer. Anal. of all of these observations indicates that SEI layer formation is a primary cause of the irreversible stress, along with some likely contribution from solvated Li-ion co-intercalation. The magnitude of these stresses is large enough to have a significant impact on the performance and cycle life of graphitic C electrodes.
10. 10

    Hao, F.; Fang, D. Diffusion-Induced Stresses of Spherical Core-Shell Electrodes in Lithium-Ion Batteries: The Effects of the Shell and Surface/Interface Stress. J. Electrochem. Soc. 2013, 160 (4), A595,  DOI: 10.1149/2.054304jes

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    Diffusion-induced stresses of spherical core-shell electrodes in lithium-ion batteries: the effects of the shell and surface/interface stress

    Hao, Feng; Fang, Daining

    Journal of the Electrochemical Society (2013), 160 (4), A595-A600CODEN: JESOAN; ISSN:0013-4651. (Electrochemical Society)

    Core-shell electrode nanoparticles improve the electrochem. performance of lithium-ion batteries, resulting from intrinsic elec. cond. and excellent tolerance to mech. stress of the shell. To study diffusion-induced stresses of core-shell nanostructures, we develop a model for spherical electrodes covered with shells including the effects of surface/interface stress, and further take carbon shell as an example. The results show that carbon shell greatly buffers the vol. expansion and alleviates tensile stresses of inner active core, and diffusion-induced stresses strongly depend on the thickness and Young's modulus of carbon layer, which should be tuned on the basis of material strengths and electrochem. capacity. In addn., residual surface/interface tension significantly reduces diffusion-induced stresses through the electrode materials, which may become a resistance to brittle fracture.
11. 11

    Suthar, B.; Northrop, P. W. C.; Braatz, R. D.; Subramanian, V. R. Optimal Charging Profiles with Minimal Intercalation-Induced Stresses for Lithium-Ion Batteries Using Reformulated Pseudo 2-Dimensional Models. J. Electrochem. Soc. 2014, 161 (11), F3144,  DOI: 10.1149/2.0211411jes

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    Optimal Charging Profiles with Minimal Intercalation-Induced Stresses for Lithium-Ion Batteries Using Reformulated Pseudo 2-Dimensional Models

    Suthar, Bharatkumar; Northrop, Paul W. C.; Braatz, Richard D.; Subramanian, Venkat R.

    Journal of the Electrochemical Society (2014), 161 (11), F3144-F3155CODEN: JESOAN; ISSN:0013-4651. (Electrochemical Society)

    This paper illustrates the application of dynamic optimization in obtaining the optimal current profile for charging a lithium-ion battery by restricting the intercalation-induced stresses to a pre-detd. limit estd. using a pseudo 2-dimensional (P2D) model. This paper focuses on the problem of maximizing the charge stored in a given time while restricting capacity fade due to intercalation-induced stresses. Conventional charging profiles for lithium-ion batteries (e.g., const. current followed by const. voltage or CC-CV) are not derived by considering capacity fade mechanisms, which are not only inefficient in terms of life-time usage of the batteries but are also slower by not taking into account the changing dynamics of the system.
12. 12

    Ngandjong, A. C.; Lombardo, T.; Primo, E. N.; Chouchane, M.; Shodiev, A.; Arcelus, O.; Franco, A. A. Investigating Electrode Calendering and Its Impact on Electrochemical Performance by Means of a New Discrete Element Method Model: Towards a Digital Twin of Li-Ion Battery Manufacturing. J. Power Sources 2021, 485, 229320  DOI: 10.1016/j.jpowsour.2020.229320

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    Investigating electrode calendering and its impact on electrochemical performance by means of a new discrete element method model: Towards a digital twin of Li-Ion battery manufacturing

    Ngandjong, Alain C.; Lombardo, Teo; Primo, Emiliano N.; Chouchane, Mehdi; Shodiev, Abbos; Arcelus, Oier; Franco, Alejandro A.

    Journal of Power Sources (2021), 485 (), 229320CODEN: JPSODZ; ISSN:0378-7753. (Elsevier B.V.)

    Lithium-ion battery (LIB) manufg. optimization is crucial to reduce its CO2 fingerprint and cost, while improving their electrochem. performance. In this article, we present an exptl. validated calendering Discrete Element Method model for LiNi0.33Mn0.33Co0.33O2-based cathodes by considering explicitly both active material (AM) and carbon-binder domain (CBD). This model was coupled to a pre-existing Coarse-Grained Mol. Dynamics model describing the slurry equilibration and its drying and a 4D-resolved Finite Element Method model for predicting electrochem. performance. Our calendering model introduces important novelties vs. the state of the art, such as the utilization of un-calendered electrode mesostructures resulting from validated simulations of the slurry and drying combined with the explicit consideration of the spatial distribution and interactions between AM and CBD particles, and its validation with both exptl. micro-indentation and porosity vs. calendering pressure curves. The effect of calendering on the electrode mesostructure is analyzed in terms of pore size distribution, tortuosity factor and particles arrangement. In addn., the evolution of the macroscopic electrochem. behavior of the electrodes upon the degree of calendering is discussed, offering added insights into the links between the calendering pressure, the electrode mesostructure and its overall performance.
13. 13

    Lim, H. D.; Park, J. H.; Shin, H. J.; Jeong, J.; Kim, J. T.; Nam, K. W.; Jung, H. G.; Chung, K. Y. A Review of Challenges and Issues Concerning Interfaces for All-Solid-State Batteries. Energy Storage Materials. 2020, 25, 224– 250,  DOI: 10.1016/j.ensm.2019.10.011

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    Hao, F.; Chen, X. First-Principles Study of Lithium Adsorption and Diffusion on Graphene: The Effects of Strain. Mater. Res. Express 2015, 2 (10), 105016  DOI: 10.1088/2053-1591/2/10/105016

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    Zhang, Q.; Tang, C.; Zhu, W.; Cheng, C. Strain-Enhanced Li Storage and Diffusion on the Graphyne as the Anode Material in the Li-Ion Battery. J. Phys. Chem. C 2018, 122 (40), 22838– 22848,  DOI: 10.1021/acs.jpcc.8b05272

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    Strain-Enhanced Li Storage and Diffusion on the Graphyne as the Anode Material in the Li-Ion Battery

    Zhang, Qiuyue; Tang, Chunmei; Zhu, Weihua; Cheng, Chun

    Journal of Physical Chemistry C (2018), 122 (40), 22838-22848CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)

    The d. functional theory is used to study the effect of the external biaxial strain on the adsorption and diffusion of Li on the graphyne as an anode material in the Li-ion battery (LIB). The increasing adsorption energy of Li on graphyne appears with the larger external biaxial strain. The Li capacity of the Li6C6 configuration for graphyne reaches 2233 mA h/g under the 12% strain, which is six times that of graphite (372 mA h/g) and two times that of graphyne without strain (1117 mA h/g). The av. open-circuit voltage is 0.50 V, which is about 0.14 eV lowered by the 12% strain and is ideal for LIBs. Li on the graphyne can diffuse easier under the 12% strain than that without strain. Furthermore, the diffusion coeff. for Li on the multilayer graphyne under the 12% strain at 300 K is fivefold of the value without strain. Excellent performances of Li capacity and Li diffusion make graphyne under the 12% strain a promising anode material for LIBs.
16. 16

    Lee, J.; Pennycook, S. J.; Pantelides, S. T. Simultaneous Enhancement of Electronic and Li⁺ Ion Conductivity in LiFePO₄. Appl. Phys. Lett. 2012, 101 (3), 033901  DOI: 10.1063/1.4737212

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    Simultaneous enhancement of electronic and Li+ ion conductivity in LiFePO4

    Lee, Jaekwang; Pennycook, Stephen J.; Pantelides, Sokrates T.

    Applied Physics Letters (2012), 101 (3), 033901/1-033901/4CODEN: APPLAB; ISSN:0003-6951. (American Institute of Physics)

    Enhancing the electronic and ionic cond. in Li compds. can significantly impact the design of batteries. Here, we explore the influence of biaxial strain on the electronic and Li+ ion conductivities of LiFePO4 by performing 1st-principles calcns. We find that 4% biaxial tensile strain (BTS) leads to 15 times increase in electronic cond. and 50 times increase in Li+ ion cond. at 300 K, resp. Electronic cond. is enhanced because BTS softens lattice distortions around a polaron, resulting in a redn. of the activation barrier. The extra vol. introduced by tensile strain also reduces the barrier of Li+ ion migration. (c) 2012 American Institute of Physics.
17. 17

    Tealdi, C.; Heath, J.; Islam, M. S. Feeling the Strain: Enhancing Ionic Transport in Olivine Phosphate Cathodes for Li- and Na-Ion Batteries through Strain Effects. J. Mater. Chem. A 2016, 4 (18), 6998– 7004,  DOI: 10.1039/C5TA09418F

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    Feeling the strain: enhancing ionic transport in olivine phosphate cathodes for Li- and Na-ion batteries through strain effects

    Tealdi, Cristina; Heath, Jennifer; Islam, M. Saiful

    Journal of Materials Chemistry A: Materials for Energy and Sustainability (2016), 4 (18), 6998-7004CODEN: JMCAET; ISSN:2050-7496. (Royal Society of Chemistry)

    Olivine-type phosphates LiFePO4 and NaFePO4 are among the most widely studied cathode materials for rechargeable batteries. To improve their rate behavior for future electronic and vehicle applications, it is vital that the Li+ and Na+ conductivities be enhanced. Atomistic simulation methods (including mol. dynamics) are used to study the effect of lattice strain on ion transport and defect formation in olivine-type LiFePO4 and NaFePO4, as these properties are directly related to their intercalation behavior. Probably, lattice strain can have a remarkable effect on the rate performance of cathode materials, with a major increase in the ionic cond. and decrease in blocking defects at room temp. Such understanding is important for the future optimization of high-rate cathodes for rechargeable batteries, and is relevant to the growing interest in developing thin film solid-state batteries.
18. 18

    Cheng, Y.-T.; Verbrugge, M. W. Diffusion-Induced Stress, Interfacial Charge Transfer, and Criteria for Avoiding Crack Initiation of Electrode Particles. J. Electrochem. Soc. 2010, 157 (4), A508,  DOI: 10.1149/1.3298892

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    Diffusion-Induced Stress, Interfacial Charge Transfer, and Criteria for Avoiding Crack Initiation of Electrode Particles

    Cheng, Yang-Tse; Verbrugge, Mark W.

    Journal of the Electrochemical Society (2010), 157 (4), A508-A516CODEN: JESOAN; ISSN:0013-4651. (Electrochemical Society)

    Most lithium-ion battery electrodes experience large vol. changes caused by concn. changes within the host particles during charging and discharging. Electrode failure, in the form of fracture or decrepitation, can occur as a result of repeated vol. changes. In this work, we first develop anal. solns. for the evolution of concn. and stresses within a spherical electrode element under charging-discharging conditions when the system thermodn. are ideal (e.g., no repulsion forces are significant between intercalate species). Both interfacial (electrochem.) kinetics and intercalate diffusion are comprehended. Based on the anal. solns., we propose tensile stress-based criteria for the initiation of cracks within a spherical insertion electrode. These criteria may help guide the development of new materials for lithium-ion batteries with enhanced mech. durability and identify battery operating conditions that, when maintained, keep the mech. stresses below acceptable values, thereby increasing cell life.
19. 19

    Lyu, Y.; Wu, X.; Wang, K.; Feng, Z.; Cheng, T.; Liu, Y.; Wang, M.; Chen, R.; Xu, L.; Zhou, J. An Overview on the Advances of LiCoO₂ Cathodes for Lithium-Ion Batteries. Adv. Energy Mater. 2021, 11 (2), 2000982  DOI: 10.1002/aenm.202000982

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    An Overview on the Advances of LiCoO2 Cathodes for Lithium-Ion Batteries

    Lyu, Yingchun; Wu, Xia; Wang, Kai; Feng, Zhijie; Cheng, Tao; Liu, Yang; Wang, Meng; Chen, Riming; Xu, Leimin; Zhou, Jingjing; Lu, Yuhao; Guo, Bingkun

    Advanced Energy Materials (2021), 11 (2), 2000982CODEN: ADEMBC; ISSN:1614-6840. (Wiley-Blackwell)

    A review. LiCoO2, discovered as a lithium-ion intercalation material in 1980 by Prof. John B. Goodenough, is still the dominant cathode for lithium-ion batteries (LIBs) in the portable electronics market due to its high compacted d., high energy d., excellent cycle life and reliability. In order to satisfy the increasing energy demand of portable electronics such as smartphones and laptops, the upper cutoff voltage of LiCoO2-based batteries has been continuously raised for achieving higher energy d. However, several detrimental issues including surface degrdn., damages induced by destructive phase transitions, and inhomogeneous reactions could emerge as charging to a high voltage (>4.2 V vs Li/Li+), which leads to the rapid decay of capacity, efficiency, and cycle life. In this review, the history and recent advances of LiCoO2 are introduced, and a significant section is dedicated to the fundamental failure mechanisms of LiCoO2 at high voltages (>4.2 V vs Li/Li+). Meanwhile, the modification strategies and the development of LiCoO2-based LIBs in industry are also discussed.
20. 20

    Diercks, D. R.; Musselman, M.; Morgenstern, A.; Wilson, T.; Kumar, M.; Smith, K.; Kawase, M.; Gorman, B. P.; Eberhart, M.; Packard, C. E. Evidence for Anisotropic Mechanical Behavior and Nanoscale Chemical Heterogeneity in Cycled LiCoO₂. J. Electrochem. Soc. 2014, 161 (11), F3039– F3045,  DOI: 10.1149/2.0071411jes

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    Evidence for Anisotropic Mechanical Behavior and Nanoscale Chemical Heterogeneity in Cycled LiCoO2

    Diercks, David R.; Musselman, Matthew; Morgenstern, Amanda; Wilson, Timothy; Kumar, Mukesh; Smith, Kandler; Kawase, Makoto; Gorman, Brian P.; Eberhart, Mark; Packard, Corinne E.

    Journal of the Electrochemical Society (2014), 161 (11), F3039-F3045CODEN: JESOAN; ISSN:0013-4651. (Electrochemical Society)

    Com. lithium-ion battery cells were cycled to various depths of discharge at various rates while the relative capacities were periodically measured. After 1000 cycles, LiCoO2 cathode material was extd. from the most severely aged cell. Nanoindentation was performed on individual LiCoO2 particles. Fractures in these particles exhibited anisotropic behavior, which was confirmed by electron microscopy and diffraction examn. indicating both intra- and inter-granular fracture occurred along {001} planes. Computation of the charge d. structure for LiCoO2 indicated that the Li-O bonds along the {001} planes require the lowest energy for cleavage, supporting the exptl. findings. Atom probe tomog. anal. indicated the nanoscale compn. distributions within specimens from both fresh and cycled material. Among the cycled particles, nanoscale inhomogeneities in the Li content were obsd. For atom probe tomog. specimens contg. grain boundaries, accumulation of Li (up to 80 at.%) on one side of the boundary was obsd. Correlation of the electrochem., mech., and compositional results indicates a combination of these mech. and chem. mechanisms contributed to the measured capacity fade.
21. 21

    Mukhopadhyay, A.; Sheldon, B. W. Deformation and Stress in Electrode Materials for Li-Ion Batteries. Prog. Mater. Sci. 2014, 63, 58– 116,  DOI: 10.1016/j.pmatsci.2014.02.001

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    Deformation and stress in electrode materials for Li-ion batteries

    Mukhopadhyay, Amartya; Sheldon, Brian W.

    Progress in Materials Science (2014), 63 (), 58-116CODEN: PRMSAQ; ISSN:0079-6425. (Elsevier Ltd.)

    A review. Structural stability and mech. integrity of electrode materials during lithiation/delithiation influence the performance of Li-ion batteries. Significant dimensional and vol. changes are assocd. with variations in lattice parameters and transformations of cryst./amorphous phases that occur during electrochem. cycling. These phenomena, which occur during Li-intercalation/deintercalation, Li-alloying/dealloying and conversion reactions, result in deformations and stress generation in the active cathode and anode materials. Such stresses can cause fragmentation, disintegration, fracturing, and loss in contact between current collectors and the active electrode materials, all of which can also expose fresh surfaces to the electrolyte. These degrdn. processes ultimately lead to capacity fade with electrochem. cycling for nearly all electrode materials, and are some of the major causes for the eventual failure of a Li-ion cell. Furthermore, severe stresses have made it nearly impossible to use higher capacity anode materials (e.g., Si, Sn) in practical batteries and also limit the 'usable' capacity of the present cathode materials (e.g., LiCoO2, LiMn2O4) to nearly half the theor. capacity. Against this backdrop, this review presents an overview of the causes and the relative magnitudes of stresses in the various electrode materials, highlights some of the more recent discoveries concerning the causes (such as stress development due to passivation layer formation), introduces the recently developed techniques for in situ observations of lithiation induced deformations and measurement of stresses, analyses the strategies adopted for addressing the stress-related issues, and raises various issues that still need to be addressed to overcome the stress related problems that are some of the major bottlenecks towards the development of new high-capacity electrode materials for Li-ion batteries.
22. 22

    Choi, Y.-M.; Pyun, S.-I. Effects of Intercalation-Induced Stress on Lithium Transport through Porous LiCoO₂ Electrode. Solid State Ionics 1997, 99 (3–4), 173– 183,  DOI: 10.1016/S0167-2738(97)00253-1

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    Effects of intercalation-induced stress on lithium transport through porous LiCoO2 electrode

    Choi, Young-Min; Pyun, Su-Il

    Solid State Ionics (1997), 99 (3,4), 173-183CODEN: SSIOD3; ISSN:0167-2738. (Elsevier)

    The lithium transport through inter- and intra-particles in porous Li1-.vdelta.CoO2 electrode was investigated in 1M LiClO4 propylene carbonate soln. by using electrochem. impedance spectroscopy combined with cyclic voltammetry. The measured contact resistance and the lithium ion diffusivity were discussed as functions of the lithium content (1-.vdelta.) and oxide particle size in terms of the lithium intercalation-induced stress.
23. 23

    Kresse, G.; Furthmüller, J. Efficient Iterative Schemes for Ab Initio Total-Energy Calculations Using a Plane-Wave Basis Set. Phys. Rev. B 1996, 54 (16), 11169– 11186,  DOI: 10.1103/PhysRevB.54.11169

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    Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set

    Kresse, G.; Furthmueller, J.

    Physical Review B: Condensed Matter (1996), 54 (16), 11169-11186CODEN: PRBMDO; ISSN:0163-1829. (American Physical Society)

    The authors present an efficient scheme for calcg. the Kohn-Sham ground state of metallic systems using pseudopotentials and a plane-wave basis set. In the first part the application of Pulay's DIIS method (direct inversion in the iterative subspace) to the iterative diagonalization of large matrixes will be discussed. This approach is stable, reliable, and minimizes the no. of order Natoms3 operations. In the second part, we will discuss an efficient mixing scheme also based on Pulay's scheme. A special "metric" and a special "preconditioning" optimized for a plane-wave basis set will be introduced. Scaling of the method will be discussed in detail for non-self-consistent and self-consistent calcns. It will be shown that the no. of iterations required to obtain a specific precision is almost independent of the system size. Altogether an order Natoms2 scaling is found for systems contg. up to 1000 electrons. If we take into account that the no. of k points can be decreased linearly with the system size, the overall scaling can approach Natoms. They have implemented these algorithms within a powerful package called VASP (Vienna ab initio simulation package). The program and the techniques have been used successfully for a large no. of different systems (liq. and amorphous semiconductors, liq. simple and transition metals, metallic and semiconducting surfaces, phonons in simple metals, transition metals, and semiconductors) and turned out to be very reliable.
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    Blöchl, P. E. Projector Augmented-Wave Method. Phys. Rev. B 1994, 50 (24), 17953– 17979,  DOI: 10.1103/PhysRevB.50.17953

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    Projector augmented-wave method

    Blochl

    Physical review. B, Condensed matter (1994), 50 (24), 17953-17979 ISSN:0163-1829.

    There is no expanded citation for this reference.
25. 25

    Zhou, F.; Cococcioni, M.; Marianetti, C. A.; Morgan, D.; Ceder, G. First-Principles Prediction of Redox Potentials in Transition-Metal Compounds with LDA + U. Phys. Rev. B 2004, 70 (23), 235121  DOI: 10.1103/PhysRevB.70.235121

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    First-principles prediction of redox potentials in transition-metal compounds with LDA+U

    Zhou, F.; Cococcioni, M.; Marianetti, C. A.; Morgan, D.; Ceder, G.

    Physical Review B: Condensed Matter and Materials Physics (2004), 70 (23), 235121/1-235121/8CODEN: PRBMDO; ISSN:1098-0121. (American Physical Society)

    First-principles calcns. within the local d. approxn. (LDA) or generalized gradient approxn. (GGA), though very successful, are known to underestimate redox potentials, such as those at which lithium intercalates in transition metal compds. We argue that this inaccuracy is related to the lack of cancellation of electron self-interaction errors in LDA/GGA and can be improved by using the DFT + U method with a self-consistent evaluation of the U parameter. We show that, using this approach, the exptl. lithium intercalation voltages of a no. of transition metal compds., including the olivine LixMPO4 (M = Mn, Fe Co, Ni), layered LixMO2 (x = Co, Ni) and spinel-like LixM2O4 (M = Mn, Co), can be reproduced accurately.
26. 26

    Laubach, S.; Laubach, S.; Schmidt, P. C.; Ensling, D.; Schmid, S.; Jaegermann, W.; Thißen, A.; Nikolowski, K.; Ehrenberg, H. Changes in the Crystal and Electronic Structure of LiCoO₂ and LiNiO₂ upon Li Intercalation and de-Intercalation. Phys. Chem. Chem. Phys. 2009, 11 (17), 3278– 3289,  DOI: 10.1039/b901200a

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    Changes in the crystal and electronic structure of LiCoO2 and LiNiO2 upon Li intercalation and de-intercalation

    Laubach, Sonja; Laubach, Stefan; Schmidt, Peter C.; Ensling, David; Schmid, Stefan; Jaegermann, Wolfram; Thissen, Andreas; Nikolowski, Kristian; Ehrenberg, Helmut

    Physical Chemistry Chemical Physics (2009), 11 (17), 3278-3289CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)

    LixCoO2 and LixNiO2 (0.5 < x < 1) are prototype cathode materials for Li ion batteries. Both systems show degrdn. and fatigue when used as cathode material during electrochem. cycling. To analyze the change of the structure and the electronic structure of LixCoO2 and LixNiO2 as a function of Li content x in detail, the authors have performed XRD, photoelectron spectroscopy (PES) and band structure calcns. for Lix(Co,Ni)O2 (0 < x ≤ 1). The calcd. d. of states (DOS) were weighted by theor. photoionization cross sections and compared with the DOS from the PES expts. Consistently, the exptl. and calcd. DOS show a broadening of the Co/Ni 3d states upon Li de-intercalation. The change of the shape of the exptl. PES curves with decreasing Li concn. can be interpreted from the calcd. partial DOS as an increasing energetic overlap of the Co/Ni 3d and O 2p states and a change in the orbital overlap of Co/Ni and O wave functions.
27. 27

    Wu, L.; Zhang, J. Ab Initio Study of Anisotropic Mechanical Properties of LiCoO₂ during Lithium Intercalation and Deintercalation Process. J. Appl. Phys. 2015, 118 (22), 225101  DOI: 10.1063/1.4937409

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    Ab initio study of anisotropic mechanical properties of LiCoO2 during lithium intercalation and deintercalation process

    Wu, Linmin; Zhang, Jing

    Journal of Applied Physics (Melville, NY, United States) (2015), 118 (22), 225101/1-225101/7CODEN: JAPIAU; ISSN:0021-8979. (American Institute of Physics)

    The mech. properties of LixCoO2 under various Li concns. and assocd. anisotropy have been systematically studied using the first principles method. During the lithium intercalation process, the Young's modulus, bulk modulus, shear modulus, and ultimate strength increase with increasing lithium concn. Strong anisotropy of mech. properties between a-axis and c-axis in LixCoO2 is identified at low lithium concns., and the anisotropy decreases with increasing lithium concn. The obsd. lithium concn. dependence and anisotropy are explained by analyzing the charge transfer using Bader charge anal., bond order anal., and bond strength by investigating partial d. of states and charge d. difference. With the decrease of Li concn., the charge depletion in the bonding regions increases, indicating a weaker Co-O bond strength. Addnl., the Young's modulus, bulk modulus, shear modulus, and toughness are obtained by simulating ab initio tensile tests. From the simulated stress-strain curves, LixCoO2 shows the highest toughness, which is in contrast with Pugh criterion prediction based on elastic properties only. (c) 2015 American Institute of Physics.
28. 28

    Kramer, D.; Ceder, G. Tailoring the Morphology of LiCoO₂: A First Principles Study. Chem. Mater. 2009, 21 (16), 3799– 3809,  DOI: 10.1021/cm9008943

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    Tailoring the Morphology of LiCoO2: A First Principles Study

    Kramer, Denis; Ceder, Gerbrand

    Chemistry of Materials (2009), 21 (16), 3799-3809CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)

    Surface energies of several low-index surfaces of layered LiCoO2 were studied as a function of the external Li and O chem. potentials by First Principles calcns. in the generalized gradient approxn. (GGA) to d. functional theory (DFT), treating on-site electron correlation within the DFT+U framework. The set of surfaces contained in the equil. shape depended on the environment. The (0001) and (10‾14) surfaces were present for all reasonable values of the Li and O chem. potentials. The (01‾12) surface, however, is stable only under oxidizing conditions. The equil. shape is sensitive to the equilibration environment because the thermodynamically favorable surface terminations and surface energies of the polar (0001) and (01‾12) surfaces are a function of the environment. This provides a lever to tailor the crystal shape according to application requirements (e.g., as active material in Li-ion batteries).
29. 29

    Zhu, Y.; Wu, D.; Yang, X.; Zeng, L.; Zhang, J.; Chen, D.; Wang, B.; Gu, M. Microscopic Investigation of Crack and Strain of LiCoO₂ Cathode Cycled under High Voltage. Energy Storage Mater. 2023, 60, 102828  DOI: 10.1016/j.ensm.2023.102828

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    Wang, L.; Li, B.; Chen, J.; Li, J.; Luo, Y.; Lv, T. Coupled Effect of SOC and SOH on Tensile Behaviors of Lithium-Ion Battery Electrodes. J. Energy Storage 2023, 68, 107782  DOI: 10.1016/j.est.2023.107782

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    Tealdi, C.; Mustarelli, P. Improving Oxygen Transport in Perovskite-Type LaGaO₃ Solid Electrolyte through Strain. J. Phys. Chem. C 2014, 118 (51), 29574– 29582,  DOI: 10.1021/jp509413w

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    Improving Oxygen Transport in Perovskite-Type LaGaO3 Solid Electrolyte through Strain

    Tealdi, Cristina; Mustarelli, Piercarlo

    Journal of Physical Chemistry C (2014), 118 (51), 29574-29582CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)

    Lattice strain is a promising possibility to improve materials performance in view of their application in thin-film devices. In particular, defect and transport properties in ionic conductors may be tailored through strain effects, since defect formation energy and migration barriers are correlated to structural parameters which, in turn, are influenced by strain-induced deformations. In this computational study we predicted that oxide-ion diffusion in perovskite-type lanthanum gallate can be improved through application of tensile strain. The structural deformations required to accommodate tensile lattice strain in the perovskite system are shown to result in a preferential localization of the oxygen vacancies in the equatorial plane of the GaO6 octahedra, while oxide-ion diffusion becomes anisotropic.
32. 32

    Henkelman, G.; Uberuaga, B. P.; Jónsson, H. A Climbing Image Nudged Elastic Band Method for Finding Saddle Points and Minimum Energy Paths. J. Chem. Phys. 2000, 113 (22), 9901– 9904,  DOI: 10.1063/1.1329672

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    A climbing image nudged elastic band method for finding saddle points and minimum energy paths

    Henkelman, Graeme; Uberuaga, Blas P.; Jonsson, Hannes

    Journal of Chemical Physics (2000), 113 (22), 9901-9904CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)

    A modification of the nudged elastic band method for finding min. energy paths is presented. One of the images is made to climb up along the elastic band to converge rigorously on the highest saddle point. Also, variable spring consts. are used to increase the d. of images near the top of the energy barrier to get an improved est. of the reaction coordinate near the saddle point. Applications to CH4 dissociative adsorption on Ir(111) and H2 on Si(100) using plane wave based d. functional theory are presented.
33. 33

    Momma, K.; Izumi, F. VESTA 3 for Three-Dimensional Visualization of Crystal, Volumetric and Morphology Data. J. Appl. Crystallogr. 2011, 44 (6), 1272– 1276,  DOI: 10.1107/S0021889811038970

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    VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data

    Momma, Koichi; Izumi, Fujio

    Journal of Applied Crystallography (2011), 44 (6), 1272-1276CODEN: JACGAR; ISSN:0021-8898. (International Union of Crystallography)

    VESTA is a 3D visualization system for crystallog. studies and electronic state calcns. It was upgraded to the latest version, VESTA 3, implementing new features including drawing the external morphpol. of crysals; superimposing multiple structural models, volumetric data and crystal faces; calcn. of electron and nuclear densities from structure parameters; calcn. of Patterson functions from the structure parameters or volumetric data; integration of electron and nuclear densities by Voronoi tessellation; visualization of isosurfaces with multiple levels, detn. of the best plane for selected atoms; an extended bond-search algorithm to enable more sophisticated searches in complex mols. and cage-like structures; undo and redo is graphical user interface operations; and significant performance improvements in rendering isosurfaces and calcg. slices.
34. 34

    Deng, Z.; Zhu, Z.; Chu, I. H.; Ong, S. P. Data-Driven First-Principles Methods for the Study and Design of Alkali Superionic Conductors. Chem. Mater. 2017, 29 (1), 281– 288,  DOI: 10.1021/acs.chemmater.6b02648

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    Data-Driven First-Principles Methods for the Study and Design of Alkali Superionic Conductors

    Deng, Zhi; Zhu, Zhuoying; Chu, Iek-Heng; Ong, Shyue Ping

    Chemistry of Materials (2017), 29 (1), 281-288CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)

    A detailed exposition of how first-principles methods can be used to guide alkali superionic conductor (ASIC) study and design is presented. Using the argyrodite Li6PS5Cl as a case study, it is demonstrated how modern information technol. (IT) infrastructure and software tools can facilitate the assessment of alkali superionic conductors in terms of various crit. properties of interest such as phase and electrochem. stability and ionic cond. The emphasis is on well-documented, reproducible anal. code that can be readily generalized to other material systems and design problems. For our chosen Li6PS5Cl case study material, it is shown that Li excess is crucial to enhancing its cond. by increasing the occupancy of interstitial sites that promote long-range Li+ diffusion between cage-like frameworks. The predicted room-temp. conductivities and activation barriers are in reasonably good agreement with exptl. values.
35. 35

    He, X.; Zhu, Y.; Epstein, A.; Mo, Y. Statistical Variances of Diffusional Properties from Ab Initio Molecular Dynamics Simulations. npj Comput. Mater. 2018, 4 (1), 18,  DOI: 10.1038/s41524-018-0074-y

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    Van der Ven, A.; Ceder, G. Lithium Diffusion Mechanisms in Layered Intercalation Compounds. J. Power Sources 2001, 97–98, 529– 531,  DOI: 10.1016/S0378-7753(01)00638-3

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    Lithium diffusion mechanisms in layered intercalation compounds

    Van der Ven, A.; Ceder, G.

    Journal of Power Sources (2001), 97-98 (), 529-531CODEN: JPSODZ; ISSN:0378-7753. (Elsevier Science S.A.)

    We investigate the mechanisms of lithium diffusion in layered intercalation compds. from first-principles. We focus on LixCoO2 and find that lithium diffusion in this compd. occurs predominantly with a divacancy mechanism. First-principles calcns. predict that the activation barrier is very sensitive to the lithium concn. due to the strongly varying c-lattice parameter of the host and the change in effective valence of the cobalt ions. This translates into a diffusion coeff. that varies by several orders of magnitude with state of charge.
37. 37

    Van der Ven, A.; Ceder, G. Lithium Diffusion in Layered Li_xCoO₂. Electrochem. Solid-State Lett. 2000, 3 (7), 301,  DOI: 10.1149/1.1391130

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    Lithium diffusion in layered LixCoO2

    Van der Ven, A.; Ceder, G.

    Electrochemical and Solid-State Letters (2000), 3 (7), 301-304CODEN: ESLEF6; ISSN:1099-0062. (Electrochemical Society)

    The results of a first principles investigation of lithium diffusion within the layered form of LixCoO2 are presented. Kinetic Monte Carlo simulations predict that lithium diffusion is mediated through a divacancy mechanism between x = 0 and x < 1 and with isolated vacancies at infinite vacancy diln. The activation barrier for the divacancy migration mechanism depends strongly on lithium concn. resulting in a diffusion coeff. that varies within several orders of magnitude. We also argue that the thermodn. factor in the expression of the chem. diffusion coeff. plays an important role at high lithium concn.
38. 38

    Liu, X.; Shi, J.; Zheng, B.; Chen, Z.; Su, Y.; Zhang, M.; Xie, C.; Su, M.; Yang, Y. Constructing a High-Energy and Durable Single-Crystal NCM811 Cathode for All-Solid-State Batteries by a Surface Engineering Strategy. ACS Appl. Mater. Interfaces 2021, 13 (35), 41669– 41679,  DOI: 10.1021/acsami.1c11419

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    Constructing a High-Energy and Durable Single-Crystal NCM811 Cathode for All-Solid-State Batteries by a Surface Engineering Strategy

    Liu, Xiangsi; Shi, Jingwen; Zheng, Bizhu; Chen, Zirong; Su, Yu; Zhang, Maojie; Xie, Chenpeng; Su, Mintao; Yang, Yong

    ACS Applied Materials & Interfaces (2021), 13 (35), 41669-41679CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)

    Single-crystal LiNi0.8Co0.1Mn0.1O2 (S-NCM811) with an electrochemomechanically compliant microstructure has attracted great attention in all-solid-state batteries (ASSBs) for its superior electrochem. performance compared to the polycryst. counterpart. However, the undesired side reactions on the cathode/solid-state electrolyte (SSE) interface causes inferior capacity and rate capability than lithium-ion batteries, limiting the practical application of S-NCM811 in the ASSB technol. Herein, it shows that S-NCM811 delivers a high capacity (205 mAh g-1, 0.1C) with outstanding rate capability (175 mAh g-1 at 0.3C and 116 mAh g-1 at 1C) in ASSBs by the coating of a nano-lithium niobium oxide (LNO) layer via the at. layer deposition technique combined with optimized post-annealing treatment. The working mechanism is verified as the nano-LNO layer effectively suppresses the decompn. of sulfide SSE and stabilizes the cathode/SSE interface. The post-annealing of the LNO layer at 400°C improves the coating uniformity, eliminates the residual lithium salts, and leads to small impedance increasing and less electrochem. polarization during cycling compared with pristine materials. This work highlights the crit. role of the post-annealed nano-LNO layer in the applications of a high-nickel cathode and offers some new insights into the designing of high-performance cathode materials for ASSBs.
39. 39

    Kang, K.; Ceder, G. Factors That Affect Li Mobility in Layered Lithium Transition Metal Oxides. Phys. Rev. B 2006, 74 (9), 094105  DOI: 10.1103/PhysRevB.74.094105

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    Factors that affect Li mobility in layered lithium transition metal oxides

    Kang, Kisuk; Ceder, Gerbrand

    Physical Review B: Condensed Matter and Materials Physics (2006), 74 (9), 094105/1-094105/7CODEN: PRBMDO; ISSN:1098-0121. (American Physical Society)

    The diffusion const. of Li in electrode materials is a key aspect of the rate capability of rechargeable Li batteries. The factors that affect Li mobility in layered Li transition metal oxides are systematically studied in this paper by first-principles calcns. In close packed oxides octahedral ions diffuse by migrating through intermediate tetrahedral sites. The activation barrier for Li hopping is strongly affected by the size of the tetrahedral site and the electrostatic interaction between Li+ in that site and the cation in the octahedron that shares a face with it. The size of the tetrahedral site is detd. by the c-lattice parameter which has a remarkably strong effect on the activation barrier for Li migration. The effect of other factors such as cation mixing and doping with nontransition metal ions can be interpreted quant. in terms of the size and electrostatic effect. A general strategy to design high rate electrode materials is discussed.
40. 40

    Li, J.-J.; Dai, Y.; Zheng, J.-C. Strain Engineering of Ion Migration in LiCoO₂. Front. Phys. 2022, 17 (1), 13503,  DOI: 10.1007/s11467-021-1086-5

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    Ning, F.; Li, S.; Xu, B.; Ouyang, C. Strain Tuned Li Diffusion in LiCoO₂ Material for Li Ion Batteries: A First Principles Study. Solid State Ion 2014, 263, 46– 48,  DOI: 10.1016/j.ssi.2014.05.008

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    Sagotra, A. K.; Chu, D.; Cazorla, C. Influence of Lattice Dynamics on Lithium-Ion Conductivity: A First-Principles Study. Phys. Rev. Mater. 2019, 3 (3), 035405  DOI: 10.1103/PhysRevMaterials.3.035405

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    Influence of lattice dynamics on lithium-ion conductivity: A first-principles study

    Sagotra, Arun K.; Chu, Dewei; Cazorla, Claudio

    Physical Review Materials (2019), 3 (3), 035405CODEN: PRMHBS; ISSN:2475-9953. (American Physical Society)

    In the context of novel solid electrolytes for solid-state batteries, first-principles calcns. are becoming increasingly more popular due to their ability to reproduce and predict accurately the energy, structural, and dynamical properties of fast-ion conductors. To accelerate the discovery of new superionic conductors is convenient to establish meaningful relations between ionic transport and simple materials descriptors. Recently, several exptl. studies on lithium fast-ion conductors suggested a correlation between lattice softness and enhanced ionic cond. due to a concomitant decrease in the activation energy for ion migration Ea. In this article, we employ extensive ab initio mol. dynamics simulations based on d. functional theory to substantiate the links between ionic transport and lattice dynamics in a no. of structurally and chem. distinct lithium superionic conductors. Our first-principles results show no evidence for a direct and general correlation between Ea, or the hopping attempt frequency ν0, and lattice softness. However, we find that, in agreement with recent observations, the pre-exponential factor of lithium diffusivity D0, which is proportional to ν0, follows the Meyer-Neldel rule idn expEa/〈ω〉 where 〈ω〉 represents an av. phonon frequency. Hence, lattice softness can be identified with enhanced lithium diffusivity, but only within families of superionic materials presenting very similar migration activation energies due to an increase in D0 (or, equivalently, in ν0). On the tech. side, we show that neglecting temp. effects in the estn. of Ea may lead to huge inaccuracies of ∼10%. The limitations of zero-temp. harmonic approaches in describing the vibrational properties of lithium-ion conductors are also illustrated.
43. 43

    Yaqoob, N.; Mücke, R.; Guillon, O.; Kaghazchi, P. Delithiation-Induced Oxygen Vacancy Formation Increases Microcracking of LiCoO₂ Cathodes. J. Power Sources 2022, 533, 231316  DOI: 10.1016/j.jpowsour.2022.231316

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    Delithiation-induced oxygen vacancy formation increases microcracking of LiCoO2 cathodes

    Yaqoob, Najma; Muecke, Robert; Guillon, Olivier; Kaghazchi, Payam

    Journal of Power Sources (2022), 533 (), 231316CODEN: JPSODZ; ISSN:0378-7753. (Elsevier B.V.)

    Cracking of cathode materials during cycling is a main cause of capacity fading in Li-ion batteries. In this work, by performing atomistic and microscale simulations, we study the possible reason behind the cracking of LixCoO2 (LxCO) microstructures. It is shown that tensile uniaxial lattice strains larger than 2% along the c-direction (εc) can cause displacement of Li ions and a yield drop in the stress-strain σc (εc) plot in LxCO. By modeling a typical microstructure consisting of packed microparticles and performing continuum mech. anal. on the mesoscale we found that the electrochem.-induced (L1.00CO → L0.50CO) mech. εc in the microstructure is, however, only - 2.5%≤εc≤ + 0.5%. Moreover, we found that even a sharp space charge region cannot cause any significant local tensile strain. However, a small amt. of oxygen vacancy (VxO) introduces a large local strain of εc = 3% leading to the displacements of Li ions. Furthermore, we found that the formation of VxO becomes more favorable with delithiation (L1.00CO → L0.50CO). The results of this work, thus, indicate that the delithiation-induced formation of VxO, which is a well-known phenomenon obsd. exptl. in operating cathode materials, can be a reason of microcracking of Li-based layered cathodes.
44. 44

    Chen, Z.; Dahn, J. R. Methods to Obtain Excellent Capacity Retention in LiCoO₂ Cycled to 4.5 V. Electrochim. Acta 2004, 49 (7), 1079– 1090,  DOI: 10.1016/j.electacta.2003.10.019

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    Methods to obtain excellent capacity retention in LiCoO2 cycled to 4.5 V

    Chen, Zhaohui; Dahn, J. R.

    Electrochimica Acta (2004), 49 (7), 1079-1090CODEN: ELCAAV; ISSN:0013-4686. (Elsevier Science B.V.)

    After reviewing early work on the effect of oxide coatings of LiCoO2 (as cathode material for secondary lithium batteries), the role of such coatings (esp. ZrO2, Al2O3, and SiO2) was evaluated. The initial report from J. Cho and G. Kim [Electrochem. Solid-State Lett., 2 (6), 253 (1999)], in which LiCoO2 coated with metal oxides can improve the capacity retention of LiCoO2 cycled to 4.4 V, has been confirmed by a no. of research groups. A summary of early work was summarized, which was followed by a summary of work from the authors' lab. that helps to clarify the role of the coating in cells charged to 4.5 V. A 30% higher energy d. than that accessed by LiCoO2 normally used in a com. cell (upper cut-off potential of 4.2 V) can be obtained with excellent capacity retention. An in-situ XRD study proved, however, that the mechanism for the improvement in capacity retention by coating proposed by J. Cho et al. is incorrect. Further expts. identified the suppression of elec. impedance growth in the cell as the key reason for the improvement caused by the oxide coatings. Other methods that are also able to suppress the impedance growth assocd. with repeated charging to 4.5 V were developed to improve the energy d. of LiCoO2 without sacrificing capacity retention. With fresh cathode surfaces, LiCoO2 can be cycled to 4.5 V and deliver a capacity of ∼180 mAh/g in a LiPF6-based electrolyte with excellent capacity retention. Furthermore, a heat-treated LiCoO2 has even better capacity retention in a Li bis(oxalato)borate-based electrolyte than in a LiPF6-based electrolyte. However, good capacity retention cannot be attained for cycling LiCoO2 at >4.5 V with respect to Li metal, presumably because of the structural changes between the O3 phase and the H1-3 phase that occur near 4.55 V.
45. 45

    Nakamura, K.; Ohno, H.; Okamura, K.; Michihiro, Y.; Moriga, T.; Nakabayashi, I.; Kanashiro, T. ⁷Li NMR Study on Li⁺ Ionic Diffusion and Phase Transition in Li_xCoO₂. Solid State Ion 2006, 177 (9–10), 821– 826,  DOI: 10.1016/j.ssi.2006.02.021

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46. 46

    Sugiyama, J.; Mukai, K.; Ikedo, Y.; Nozaki, H.; Månsson, M.; Watanabe, I. Li Diffusion in Li_xCoO₂ Probed by Muon-Spin Spectroscopy. Phys. Rev. Lett. 2009, 103 (14), 147601  DOI: 10.1103/PhysRevLett.103.147601

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    Li Diffusion in LixCoO2 Probed by Muon-Spin Spectroscopy

    Sugiyama, Jun; Mukai, Kazuhiko; Ikedo, Yutaka; Nozaki, Hiroshi; Mansson, Martin; Watanabe, Isao

    Physical Review Letters (2009), 103 (14), 147601/1-147601/4CODEN: PRLTAO; ISSN:0031-9007. (American Physical Society)

    The diffusion coeff. of Li+ ions (DLi) in the battery material LixCoO2 has been investigated by muon-spin relaxation (μ+SR). Based on expts. in zero and weak longitudinal fields at temps. up to 400 K, we detd. the fluctuation rate (ν) of the fields on the muons due to their interaction with the nuclear moments. Combined with susceptibility data and electrostatic potential calcns., clear Li+ ion diffusion was detected above ∼150 K. The DLi estd. from ν was in very good agreement with predictions from first-principles calcns., and we present the μ+SR technique as an optimal probe to detect DLi for materials contg. magnetic ions.
47. 47

    Kang, K.; Meng, Y. S.; Bréger, J.; Grey, C. P.; Ceder, G. Electrodes with High Power and High Capacity for Rechargeable Lithium Batteries. Science (1979) 2006, 311 (5763), 977– 980,  DOI: 10.1126/science.1122152

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    Qi, Y.; Hector, L. G.; James, C.; Kim, K. J. Lithium Concentration Dependent Elastic Properties of Battery Electrode Materials from First Principles Calculations. J. Electrochem. Soc. 2014, 161 (11), F3010,  DOI: 10.1149/2.0031411jes

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    Lithium Concentration Dependent Elastic Properties of Battery Electrode Materials from First Principles Calculations

    Qi, Yue; Hector, Louis G., Jr.; James, Christine; Kim, Kwang Jin

    Journal of the Electrochemical Society (2014), 161 (11), F3010-F3018CODEN: JESOAN; ISSN:0013-4651. (Electrochemical Society)

    This paper aims to help fill a gap in the literature on Li-ion battery electrode materials due to the absence of measured elastic consts. needed for diffusion induced stress models. By examg. results from new 1st principles d. functional theory (DFT) calcns. of LiCoO2, LiMn2O4, (and their delithiated hosts, CoO2 and MnO2), LixAl alloys, and data from the extant literature on LiFePO4 (and FePO4), LiTi2O4 (and Li2Ti2O4), LixSi, LixSn and lithium graphite-interaction-compds., a compelling picture emerges on the dependency of the elastic properties on Li concn. Specifically, 3 distinct categories of behavior are found: (a) the averaged Young's moduli change very minimally upon lithiation of the spinel and olivine structures; (b) lithiation induced stiffening is obsd. only when new and stronger bonds between the Li ions and the host materials are formed in layered compds.; and (c) for alloy-forming electrode materials, such as Si, β-Sn and Al, the averaged Young's moduli of lithiated compds. follow the linear rule of mixts. The tendency of ductile or brittle behavior electrode materials is studied with the Pugh criterion, and a ductile to brittle transition occurs during lithiation of Al and β-Sn, but not in Si.
49. 49

    Zou, Z.; Ma, N.; Wang, A.; Ran, Y.; Song, T.; Jiao, Y.; Liu, J.; Zhou, H.; Shi, W.; He, B.; Wang, D.; Li, Y.; Avdeev, M.; Shi, S. Relationships Between Na+ Distribution, Concerted Migration, and Diffusion Properties in Rhombohedral NASICON. Adv. Energy Mater. 2020, 10 (30), 2001486  DOI: 10.1002/aenm.202001486

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    49

    Relationships Between Na+ Distribution, Concerted Migration, and Diffusion Properties in Rhombohedral NASICON

    Zou, Zheyi; Ma, Nan; Wang, Aiping; Ran, Yunbing; Song, Tao; Jiao, Yao; Liu, Jinping; Zhou, Hang; Shi, Wei; He, Bing; Wang, Da; Li, Yajie; Avdeev, Maxim; Shi, Siqi

    Advanced Energy Materials (2020), 10 (30), 2001486CODEN: ADEMBC; ISSN:1614-6840. (Wiley-Blackwell)

    Rhombohedral NaZr2(PO4)3 is the prototype of all the NASICON-type materials. The ionic diffusion in these rhombohedral NASICON materials is highly influenced by the ionic migration channels and the bottlenecks in the channels which have been extensively studied. However, no consensus is reached as to which one is the preferential ionic migration channel. Moreover, the relationships between the Na+ distribution over the multiple available sites, concerted migration, and diffusion properties remain elusive. Using ab initio mol. dynamics simulations, here it is shown that the Na+ ions tend to migrate through the Na1-Na3-Na2-Na3-Na1 channels rather than through the Na2-Na3-Na3-Na2 channels. There are two types of concerted migration mechanisms: two Na+ ions located at the adjacent Na1 and Na2 sites can migrate either in the same direction or at an angle. Both mechanisms exhibit relatively low migration barriers owing to the potential energy conversion during the Na+ ions migration process. Redistribution of Na+ ions from the most stable Na1 sites to Na2 on increasing Na+ total content further facilitates the concerted migration and promotes the Na+ ion mobility. The work establishes a connection between the Na+ concn. in rhombohedral NASICON materials and their diffusion properties.
50. 50

    Kozinsky, B.; Akhade, S. A.; Hirel, P.; Hashibon, A.; Elsässer, C.; Mehta, P.; Logeat, A.; Eisele, U. Effects of Sublattice Symmetry and Frustration on Ionic Transport in Garnet Solid Electrolytes. Phys. Rev. Lett. 2016, 116 (5), 055901  DOI: 10.1103/PhysRevLett.116.055901

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    50

    Effects of sublattice symmetry and frustration on ionic transport in garnet solid electrolytes

    Kozinsky, Boris; Akhade, Sneha A.; Hirel, Pierre; Hashibon, Adham; Elsasser, Christian; Mehta, Prateek; Logeat, Alan; Eisele, Ulrich

    Physical Review Letters (2016), 116 (5), 055901/1-055901/5CODEN: PRLTAO; ISSN:0031-9007. (American Physical Society)

    We use rigorous group-theoretic techniques and mol. dynamics to investigate the connection between structural symmetry and ionic cond. in the garnet family of solid Li-ion electrolytes. We identify new ordered phases and order-disorder phase transitions that are relevant for cond. optimization. Ionic transport in this materials family is controlled by the frustration of the Li sublattice caused by incommensurability with the host structure at noninteger Li concns., while ordered phases explain regions of sharply lower cond. Disorder is therefore predicted to be optimal for ionic transport in this and other conductor families with strong Li interaction.
51. 51

    Düvel, A.; Heitjans, P.; Fedorov, P.; Scholz, G.; Cibin, G.; Chadwick, A. V.; Pickup, D. M.; Ramos, S.; Sayle, L. W. L.; Sayle, E. K. L.; Sayle, T. X. T.; Sayle, D. C. Is Geometric Frustration-Induced Disorder a Recipe for High Ionic Conductivity?. J. Am. Chem. Soc. 2017, 139 (16), 5842– 5848,  DOI: 10.1021/jacs.7b00502

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    51

    Is Geometric Frustration-Induced Disorder a Recipe for High Ionic Conductivity?

    Duevel, Andre; Heitjans, Paul; Fedorov, Pavel; Scholz, Gudrun; Cibin, Giannantonio; Chadwick, Alan V.; Pickup, David M.; Ramos, Silvia; Sayle, Lewis W. L.; Sayle, Emma K. L.; Sayle, Thi X. T.; Sayle, Dean C.

    Journal of the American Chemical Society (2017), 139 (16), 5842-5848CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)

    Ionic cond. is ubiquitous to many industrially important applications such as fuel cells, batteries, sensors, and catalysis. Tunable cond. in these systems is therefore key to their com. viability. Here, we show that geometric frustration can be exploited as a vehicle for cond. tuning. In particular, we imposed geometric frustration upon a prototypical system, CaF2, by ball milling it with BaF2, to create nanostructured Ba1-xCaxF2 solid solns. and increased its ionic cond. by over 5 orders of magnitude. By mirroring each expt. with MD simulation, including "simulating synthesis", we reveal that geometric frustration confers, on a system at ambient temp., structural and dynamical attributes that are typically assocd. with heating a material above its superionic transition temp. These include structural disorder, excess vol., pseudovacancy arrays, and collective transport mechanisms; we show that the excess vol. correlates with ionic cond. for the Ba1-xCaxF2 system. We also present evidence that geometric frustration-induced cond. is a general phenomenon, which may help explain the high ionic cond. in doped fluorite-structured oxides such as ceria and zirconia, with application for solid oxide fuel cells. A review on geometric frustration [ Nature 2015, 521, 303] remarks that classical crystallog. is inadequate to describe systems with correlated disorder, but that correlated disorder has clear crystallog. signatures. Here, we identify two possible crystallog. signatures of geometric frustration: excess vol. and correlated "snake-like" ionic transport; the latter infers correlated disorder. In particular, as one ion in the chain moves, all the other (correlated) ions in the chain move simultaneously. Critically, our simulations reveal snake-like chains, over 40 Å in length, which indicates long-range correlation in our disordered systems. Similarly, collective transport in glassy materials is well documented [for example, J. Chem. Phys. 2013, 138, 12A538]. Possible crystallog. nomenclatures, to be used to describe long-range order in disordered systems, may include, for example, the shape, length, and branching of the "snake" arrays. Such characterizations may ultimately provide insight and differences between long-range order in disordered, amorphous, or liq. states and processes such as ionic cond., melting, and crystn.
52. 52

    Barai, A.; Guo, Y.; McGordon, A.; Jennings, P. A Study of the Effects of External Pressure on the Electrical Performance of a Lithium-Ion Pouch Cell. 2013 Int. Conf. Connected Vehicles Expo (ICCVE) 2013, 295– 299,  DOI: 10.1109/ICCVE.2013.6799809

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53. 53

    Hoshino, H.; Yanagiya, H.; Shimoji, M. Effect of Hydrostatic Pressure on the Electrical Conductivity of Ag₃SBr and β-Ag₃SI. Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases 1974, 70, 281– 286,  DOI: 10.1039/f19747000281

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    53

    Effect of hydrostatic pressure on the electrical conductivity of silver bromide sulfide (Ag3SBr) and β-silver iodide sulfide (Ag3SI)

    Hoshino, H.; Yanagiya, H.; Shimoji, M.

    Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases (1974), 70 (2), 281-6CODEN: JCFTAR; ISSN:0300-9599.

    The elec. cond. of Ag3SBr and β-Ag3SI was measured at 0-3.15 × 108 N/m2 and 293-373°K using an a.c. bridge. The electronic cond. was also detd. using a Wagner type polarization cell. The resistances of Ag3SBr and β-Ag3SI pellets were proportional to the sample thickness at 298°K. The temp. dependence of the activation vols. was also examd.
54. 54

    Famprikis, T.; Kudu, O. U.; Dawson, J. A.; Canepa, P.; Fauth, F.; Suard, E.; Zbiri, M.; Dambournet, D.; Borkiewicz, O. J.; Bouyanfif, H.; Emge, S. P.; Cretu, S.; Chotard, J. N.; Grey, C. P.; Zeier, W. G.; Islam, M. S.; Masquelier, C. Under Pressure: Mechanochemical Effects on Structure and Ion Conduction in the Sodium-Ion Solid Electrolyte Na₃PS₄. J. Am. Chem. Soc. 2020, 142 (43), 18422– 18436,  DOI: 10.1021/jacs.0c06668

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    Under Pressure: Mechanochemical Effects on Structure and Ion Conduction in the Sodium-Ion Solid Electrolyte Na3PS4

    Famprikis, Theodosios; Kudu, O. Ulas; Dawson, James A.; Canepa, Pieremanuele; Fauth, Francois; Suard, Emmanuelle; Zbiri, Mohamed; Dambournet, Damien; Borkiewicz, Olaf J.; Bouyanfif, Houssny; Emge, Steffen P.; Cretu, Sorina; Chotard, Jean-Noel; Grey, Clare P.; Zeier, Wolfgang G.; Islam, M. Saiful; Masquelier, Christian

    Journal of the American Chemical Society (2020), 142 (43), 18422-18436CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)

    Fast-ion conductors are crit. to the development of solid-state batteries. The effects of mechanochem. synthesis that lead to increased ionic cond. in an archetypical sodium-ion conductor Na3PS4 are not fully understood. We present here a comprehensive anal. based on diffraction (Bragg and pair distribution function), spectroscopy (impedance, Raman, NMR and INS), and ab initio simulations aimed at elucidating the synthesis-property relationships in Na3PS4. We consolidate previously reported interpretations regarding the local structure of ball-milled samples, underlining the sodium disorder and showing that a local tetragonal framework more accurately describes the structure than the originally proposed cubic one. Through variable-pressure impedance spectroscopy measurements, we report for the first time the activation vol. for Na+ migration in Na3PS4, which is ~ 30% higher for the ball-milled samples. Moreover, we show that the effect of ball-milling on increasing the ionic cond. of Na3PS4 to ~ 10-4 S/cm can be reproduced by applying external pressure on a sample from conventional high-temp. ceramic synthesis. We conclude that the key effects of mechanochem. synthesis on the properties of solid electrolytes can be analyzed and understood in terms of pressure, strain, and activation vol.
55. 55

    Fu, Z. H.; Chen, X.; Zhao, C. Z.; Yuan, H.; Zhang, R.; Shen, X.; Ma, X. X.; Lu, Y.; Liu, Q. B.; Fan, L. Z.; Zhang, Q. Stress Regulation on Atomic Bonding and Ionic Diffusivity: Mechanochemical Effects in Sulfide Solid Electrolytes. Energy Fuels 2021, 35 (12), 10210– 10218,  DOI: 10.1021/acs.energyfuels.1c00488

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    55

    Stress Regulation on Atomic Bonding and Ionic Diffusivity: Mechanochemical Effects in Sulfide Solid Electrolytes

    Fu, Zhong-Heng; Chen, Xiang; Zhao, Chen-Zi; Yuan, Hong; Zhang, Rui; Shen, Xin; Ma, Xia-Xia; Lu, Yang; Liu, Quan-Bing; Fan, Li-Zhen; Zhang, Qiang

    Energy & Fuels (2021), 35 (12), 10210-10218CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)

    External pressure is widely applied to the fabrication and assembling of solid-state batteries, which can reduce grain sizes, enhance solid-solid contacts, and further increase the ionic cond. of solid electrolytes. However, the effect of stress on the intrinsic ionic cond. of solid electrolytes is not yet fully understood. Herein, a comprehensive first-principles investigation was performed to elucidate the effect of tensile and compressive stresses on the ionic diffusivity of a sulfide solid electrolyte prototype Li10GeP2S12 (LGPS). A reduced and increased ionic diffusivity is obsd. in LGPS under compressive and tensile stress, resp. Several descriptors, including the lattice vol., the neck size, the Li vacancy formation energy, and the Li Bader charge, are proposed to reveal the evolution of the ionic diffusivity in LGPS under stress. The ionic diffusivity in LGPS exhibits a better correlation with the activation energy than the pre-exponential factor, which suggests a synergy of stress and temp. on the ionic diffusivity. A more obvious change of ionic diffusivity as the stress is expected under lower temps. These results afford a fundamental and deep understanding of the mechanochem. effect in solid electrolytes.
56. 56

    Schneider, C.; Schmidt, C. P.; Neumann, A.; Clausnitzer, M.; Sadowski, M.; Harm, S.; Meier, C.; Danner, T.; Albe, K.; Latz, A.; Wall, W. A.; Lotsch, B. V. Effect of Particle Size and Pressure on the Transport Properties of the Fast Ion Conductor t-Li₇SiPS₈. Adv. Energy Mater. 2023, 13 (15), 2203873  DOI: 10.1002/aenm.202203873

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    56

    Effect of Particle Size and Pressure on the Transport Properties of the Fast Ion Conductor t-Li7SiPS8

    Schneider, Christian; Schmidt, Christoph P.; Neumann, Anton; Clausnitzer, Moritz; Sadowski, Marcel; Harm, Sascha; Meier, Christoph; Danner, Timo; Albe, Karsten; Latz, Arnulf; Wall, Wolfgang A.; Lotsch, Bettina V.

    Advanced Energy Materials (2023), 13 (15), 2203873CODEN: ADEMBC; ISSN:1614-6840. (Wiley-Blackwell)

    All-solid-state batteries promise higher energy and power densities as well as increased safety compared to lithium-ion batteries by using non-flammable solid electrolytes and metallic lithium as the anode. Ensuring permanent and close contact between the components and individual particles is crucial for long-term operation of a solid-state cell. This study investigates the particle size dependent compression mechanics and ionic cond. of the mech. soft thiophosphate solid electrolyte tetragonal Li7SiPS8 (t-LiSiPS) under pressure. The effect of stack and pelletizing pressure is demonstrated as a powerful tool to influence the microstructure and, hence, ionic cond. of t-LiSiPS. Heckel anal. for granular powder compression reveals distinct pressure regimes, which differently impact the Li ion cond. The pelletizing process is simulated using the discrete element method followed by finite vol. anal. to disentangle the effects of pressure-dependent microstructure evolution from atomistic activation vol. effects. Furthermore, it is found that the relative d. of a tablet is a weaker descriptor for the sample's impedance compared to the particle size distribution. The multiscale exptl. and theor. study thus captures both atomistic and microstructural effects of pressure on the ionic cond., thus emphasizing the importance of microstructure, particle size distribution and pressure control in solid electrolytes.
57. 57

    Radzilowski, R. H.; Kummer, J. T. The Hydrostatic Pressure Dependence of the Ionic Conductivity of β-Aluminas. J. Electrochem. Soc. 1971, 118 (5), 714,  DOI: 10.1149/1.2408152

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    Hydrostatic pressure dependence of the ionic conductivity of β-aluminas

    Radzilowski, Ronald H.; Kummer, Joseph T.

    Journal of the Electrochemical Society (1971), 118 (5), 714-16CODEN: JESOAN; ISSN:0013-4651.

    The ionic cond. of M2O.11Al2O3 increases linearly up to 4000 atm with M = Li, remains const. for M = Na, and decreases for M = K. Diffusion of ions depends on the activation vol. of the crystal lattice in the vicinity of the mobile cation. In the β-Al2O3 lattice, Na ions move without serious steric hindrance, whereas K-substituted β-Al2O3 requires lattice expansion. Conversely, the net effect of Li ion motion is a local contraction of the lattice.
58. 58

    Jagad, H. D.; Harris, S. J.; Sheldon, B. W.; Qi, Y. Tradeoff between the Ion Exchange-Induced Residual Stress and Ion Transport in Solid Electrolytes. Chem. Mater. 2022, 34 (19), 8694– 8704,  DOI: 10.1021/acs.chemmater.2c01806

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    58

    Tradeoff between the Ion Exchange-Induced Residual Stress and Ion Transport in Solid Electrolytes

    Jagad, Harsh D.; Harris, Stephen J.; Sheldon, Brian W.; Qi, Yue

    Chemistry of Materials (2022), 34 (19), 8694-8704CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)

    Rapid filament growth of lithium is limiting the commercialization of solid-state lithium metal anode batteries. Recent work demonstrated that lithium filaments grow into pre-existing or nascent cracks in the solid electrolyte, suggesting that increasing the fracture toughness of the solid electrolytes will inhibit filament penetration. It has been suggested that introducing residual compressive stresses at the surface of the solid electrolyte can provide this addnl. fracture toughness. One of the ways to induce these residual compressive stresses is by exchanging lithium ions (Li+) with larger isovalent ions such as potassium (K+). On the other hand, incorporation of too much potassium can alter the lithium-ion diffusion pathway and lower the diffusivity, thus limiting the performance of the solid-state electrolyte. Using multiscale modeling methods, we optimize this tradeoff and predict that exchanging 3.4% potassium ions up to a depth twice the grain sizes in Li7La3Zr2O12 solid electrolyte can induce a max. residual compressive stress of around 1.1 GPa, corresponding to an increase in fracture strength by ∼8 times, while lowering the diffusivity in the ion-exchanged region by a factor of 5 at room temp. The redn. of lithium diffusivity is due to K+-induced stress and (mainly) blockage of lithium ion pathways in the shallow ion-exchanged layer.
59. 59

    Haruyama, J.; Sodeyama, K.; Han, L.; Takada, K.; Tateyama, Y. Space–Charge Layer Effect at Interface between Oxide Cathode and Sulfide Electrolyte in All-Solid-State Lithium-Ion Battery. Chem. Mater. 2014, 26 (14), 4248– 4255,  DOI: 10.1021/cm5016959

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    59

    Space-Charge Layer Effect at Interface between Oxide Cathode and Sulfide Electrolyte in All-Solid-State Lithium-Ion Battery

    Haruyama, Jun; Sodeyama, Keitaro; Han, Liyuan; Takada, Kazunori; Tateyama, Yoshitaka

    Chemistry of Materials (2014), 26 (14), 4248-4255CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)

    The authors theor. elucidated the characteristics of the space-charge layer (SCL) at interfaces between oxide cathode and sulfide electrolyte in all-solid-state Li-ion batteries (ASS-LIBs) and the effect of the buffer layer interposition, for the 1st time, via the calcns. with d. functional theory (DFT) + U framework. As a most representative system, the authors examd. the interfaces between LiCoO2 cathode and β-Li3PS4 solid electrolyte (LCO/LPS), and the LiCoO2/LiNbO3/β-Li3PS4 (LCO/LNO/LPS) interfaces with the LiNbO3 buffer layers. The DFT+U calcns., coupling with a systematic procedure for interface matching, showed the stable structures and the electronic states of the interfaces. The LCO/LPS interface has attractive Li adsorption sites and rather disordered structure, whereas the interposition of the LNO buffer layers forms smooth interfaces without Li adsorption sites for both LCO and LPS sides. The calcd. energies of the Li-vacancy formation and the Li migration reveal that subsurface Li in the LPS side can begin to transfer at the under-voltage condition in the LCO/LPS interface, which suggests the SCL growth at the beginning of charging, leading to the interfacial resistance. The LNO interposition suppresses this growth of SCL and provides smooth Li transport paths free from the possible bottlenecks. These aspects on the at. scale will give a useful perspective for the further improvement of the ASS-LIB performance.
60. 60

    Hoang, K.; Johannes, M. D. Defect Chemistry in Layered Transition-Metal Oxides from Screened Hybrid Density Functional Calculations. J. Mater. Chem. A Mater. 2014, 2 (15), 5224– 5235,  DOI: 10.1039/C4TA00673A

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    Defect chemistry in layered transition-metal oxides from screened hybrid density functional calculations

    Hoang, Khang; Johannes, Michelle D.

    Journal of Materials Chemistry A: Materials for Energy and Sustainability (2014), 2 (15), 5224-5235CODEN: JMCAET; ISSN:2050-7496. (Royal Society of Chemistry)

    We report a comprehensive first-principles study of the thermodn. and transport of intrinsic point defects in layered oxide cathode materials LiMO2 (M = Co, Ni), using d.-functional theory and the Heyd-Scuseria-Ernzerhof screened hybrid functional. We find that LiCoO2 has a complex defect chem.; different electronic and ionic defects can exist under different synthesis conditions, and LiCoO2 samples free of cobalt antisite defects can be made under Li-excess (Co-deficient) environments. A defect model for lithium over-stoichiometric LiCoO2 is also proposed, which involves neg. charged lithium antisites and pos. charged small (hole) polarons. In LiNiO2, a certain amt. of Ni3+ ions undergo charge disproportionation and the concn. of nickel ions in the lithium layers is high. Tuning the synthesis conditions may reduce the nickel antisites but would not remove the charge disproportionation. In addn., we find that LiMO2 cannot be doped n- or p-type; the electronic conduction occurs via hopping of small polarons and the ionic conduction occurs via migration of lithium vacancies, either through a monovacancy or divacancy mechanism, depending on the vacancy concn.
61. 61

    James, C.; Wu, Y.; Sheldon, B.; Qi, Y. Computational Analysis of Coupled Anisotropic Chemical Expansion in Li_2-XMnO_3-δ. MRS Adv. 2016, 1 (15), 1037– 1042,  DOI: 10.1557/adv.2016.48

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    Computational Analysis of Coupled Anisotropic Chemical Expansion in Li2-XMnO3-δ

    James, Christine; Wu, Yan; Sheldon, Brian; Qi, Yue

    MRS Advances (2016), 1 (15), 1037-1042CODEN: MARDCQ; ISSN:2059-8521. (Cambridge University Press)

    During the activation and charge process, vacancies are generated in the Li2MnO3 component in lithium-rich layered cathode materials. The chem. expansion coeff. tensor assocd. with oxygen vacancies, lithium vacancies and a Li-O vacancy pair were calcd. for Li2-xMnO3-δ. The chem. expansion coeff. was larger for oxygen vacancies than for lithium vacancies in most directions. Addnl., the chem. expansion coeff. for a Li-O vacancy pair was shown to not be a linear sum of the chem. expansion coeffs. of the two vacancy types, suggesting that the oxygen vacancies and lithium vacancies in Li2-XMnO3-δ exhibit a coupling effect.
62. 62

    Gillan, M. J. The Elastic Dipole Tensor for Point Defects in Ionic Crystals. Journal of Physics C: Solid State Physics 1984, 17 (9), 1473,  DOI: 10.1088/0022-3719/17/9/006

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    The elastic dipole tensor for point defects in ionic crystals

    Gillan, M. J.

    Journal of Physics C: Solid State Physics (1984), 17 (9), 1473-88CODEN: JPSOAW; ISSN:0022-3719.

    The problem of calcg. the elastic dipole tensor (G) for point defects in ionic crystals is discussed. The relation between G and the deriv. with respect to bulk strain of the defect formation energy ΔE provides a natural and practical means of calcg. G. This relation may be exploited either by computing ΔE for a series of values of strain and extg. the deriv. numerically, or by making use of an explicit expression for G in terms of the relaxed ionic positions. The method of calcn. is illustrated for some color centers for which expt. values of G are available: the H, Vk, and O2- centers in alkali halides and the V- center in MgO. Agreement with expt. is obtained for the H and O2- centers, but rather poor agreement for the Vk and V- centers.