Advanced TiO2/Al2O3 Bilayer ALD Coatings for Improved Lithium-Rich Layered Oxide Electrodes

Surface modification is a highly effective strategy for addressing issues in lithium-rich layered oxide (LLO) cathodes, including phase transformation, particle cracking, oxygen gas release, and transition-metal ion dissolution. Existing single-/double-layer coating strategies face drawbacks such as poor component contact and complexity. Herein, we present the results of a low-temperature atomic layer deposition (ALD) process for creating a TiO2/Al2O3 bilayer on composite cathodes made of AS200 (Li1.08Ni0.34Co0.08Mn0.5O2). Electrochemical analysis demonstrates that TiO2/Al2O3-coated LLO electrodes exhibit improved discharge capacities and enhanced capacity retention compared with uncoated samples. The TAA-5/AS200 bilayer-coated electrode, in particular, demonstrates exceptional capacity retention (∼90.4%) and a specific discharge capacity of 146 mAh g–1 after 100 cycles at 1C within the voltage range of 2.2 to 4.6 V. The coated electrodes also show reduced voltage decay, lower surface film resistance, and improved interfacial charge transfer resistances, contributing to enhanced stability. The ALD-deposited TiO2/Al2O3 bilayer coatings exhibit promising potential for advancing the electrochemical performance of lithium-rich layered oxide cathodes in lithium-ion batteries.


Figure S1 .
Figure S1.XRD patterns of AS200 with different single-layer coatings.

Figure S2 .
Figure S2.TEM images of AS200 with different single-layer coatings.

Figure S3 .
Figure S3.Charge-discharge curves of all samples at different C-rates within the voltage range of 2.2V to 4.6V.

Figure S4 .
Figure S4.Rate performance comparison of AS200 with 3nm-thick and 5nm-thick single-layer coatings.Charge-discharge curves at various C-rates provide insight into the electrochemical behavior.

Figure S5 .
Figure S5.Cycling performance of all samples under 1 C, along with corresponding chargedischarge curves at different cycles.

Figure S6 .
Figure S6.SEM image of all samples, capturing their morphological features both before and after 100 cycles at 0.1 C within the voltage range of 2.2V to 4.6V.

Figure S7 .
Figure S7.Ex-situ XRD patterns of all samples after 100 cycles at 0.1 C within the voltage range of 2.2V to 4.6V.

Figure S8 .
Figure S8.XPS spectrum of all samples following 100 cycles at 0.1 C within the voltage range of 2.2V to 4.6V.

Figure S7 .
Figure S7.(a) Ex-situ XRD patterns of AS200, TAA-3, and TAA-5 electrodes after 100 cycles at 0.1 C within the voltage range of 2.2V to 4.6V.(b) provides a detailed magnification of XRD patterns between 43° to 46°, and (c) focuses on patterns within the range of 60° to 70°.