ACS Publications. Most Trusted. Most Cited. Most Read
Oriented Carbon Fiber Networks by Design from Renewables for Electrochemical Applications
My Activity

Figure 1Loading Img
  • Open Access
Research Article

Oriented Carbon Fiber Networks by Design from Renewables for Electrochemical Applications
Click to copy article linkArticle link copied!

Open PDFSupporting Information (1)

ACS Sustainable Chemistry & Engineering

Cite this: ACS Sustainable Chem. Eng. 2021, 9, 36, 12142–12154
Click to copy citationCitation copied!
https://doi.org/10.1021/acssuschemeng.1c03549
Published September 1, 2021

Copyright © 2021 The Authors. Published by American Chemical Society. This publication is licensed under

CC-BY 4.0 .

Abstract

Click to copy section linkSection link copied!

With the explosion of global demands for electrified mobility systems and a surge in rural energy transport mechanisms augmented by the scarcity of key metals, carbon by design has become a transformational pathway to fill the gap as an energy material of choice. The development of functional carbon from renewables with outstanding electrostatic double-layer capacitance is still in its infancy, as there is a significant gap in understanding the relationship between the tunable structure and properties of the bioresources both before and after their controlled carbonization. Herein, we report carbon fiber networks (CFNs) with highly controllable intact structure manufactured from four functional lignins originating from different types of processing residues, demonstrating excellent electrochemical efficacies, which makes them promising self-standing electrodes in supercapacitors. This study also underpins the feasibility and importance of preparing CFNs with highly oriented structure, which endows superior specific capacitance and cycle stability compared to the CFNs with randomly oriented fibers. The randomly oriented CFNs reached a specific capacitance value of 456 F g–1 under current densities of 1 A g–1 and a cycle stability of 73.6%, while the CFNs with an orientation factor of 0.87 exhibited significant improvement of the specific capacitance by approximately 15% (529 F g–1) and the cycle stability reached 95% after 10 000 charge–discharge cycles. The high specific capacitance and excellent overall electrochemical properties of the highly oriented CFNs make them a cost-effective and greener material of choice for energy storage devices.

This publication is licensed under

CC-BY 4.0 .
  • cc licence
  • by licence
Copyright © 2021 The Authors. Published by American Chemical Society

Synopsis

Green carbon fiber networks with outstanding electrochemical performance can be produced from lignin, a main byproduct in biorefinery and paper-making industries.

Introduction

Click to copy section linkSection link copied!

As an important polymeric component in plants, lignin can be found in wood, grass, and algae, etc. It primarily arises from the enzymatic dehydrogenative polymerization of three phenyl propanoid monomers (monolignols), namely, p-coumaryl, coniferyl, and sinapyl alcohols. (1,2) These monolignols are linked in a complex network through different types of ether and carbon–carbon bonds by a biosynthesis process which leads to the generation of a complex, three-dimensional polymer. (2) Because of the complexity of their chemical compositions, the exact structure of the extracted functional lignins varies based on the feedstock. The extraction methods also have significant effects on the structure of the obtained lignin because there is no way to isolate the native lignin in a chemically unaltered form. (3) Generally, kraft, soda, and organosolv pulping processes can be used to extract lignin, and the obtained functional lignins are subsequently named as kraft lignin, soda lignin, and organosolv lignin, respectively.
Kraft pulping is now the globally predominant technique for the production of lignin. (4) During the process, lignin reacts with the hydroxide and hydrosulfide anions, which cleave the lignin chains. Thiol groups are introduced into the side chains, which leads to an increase in the sulfur content in the kraft lignin. (5,6) Lignoboost lignin is another functional lignin, which is produced using the kraft process but with optimized filtration steps. Thus, the ash and sulfur contents in lignoboost lignin are relatively low. (7) Compared to the kraft process, soda pulping uses only sodium hydroxide as the cooking chemical. Currently, the soda process is primarily used on annual fiber feedstock. (8,9) On the other hand, hydrolytic enzymes are widely used in the biofuel industry to treat the lignin-containing biomass, and hydrolysis lignin is obtained as a byproduct after this process. (10,11)
Different feedstocks and extraction techniques lead to functional lignins with different chemical compositions and structures, and the chemical structure will affect the practical applications of lignin. Even though lignin is an extensively underutilized industrial byproduct, there are current trends to valorize lignin in various fields. (12−18) Due to its abundant aromatic structure and low costs, lignin is considered as an attractive precursor for the production of renewable carbon materials, especially in making carbon fibers. (19−22) Baker et al. melt-spun organic-purified hardwood kraft lignin, and after thermal stabilization and carbonization at 1000 °C, lignin-based carbon fibers with a diameter of approximately 10 μm were obtained. (23) These carbon fibers had a tensile modulus and strength of 28.6 and 0.52 GPa, respectively. Later, high-ash-containing corn stover organosolv lignin was melt-spun and converted to carbon fibers by Qu et al., resulting in fibers with an average tensile modulus of 62 GPa. (24) There are several other studies on the mechanical properties of the lignin-based carbon fibers, but none of them can reach the requirements for carbon fibers used for mechanical components. (19,25−27)
In fact, as opposed to mechanical usage, lignin-based carbon fibers are more suitable for energy storage applications because the complex and oxygen-containing compounds tend to form porous structures during carbonization, which is advantageous for storing energy. (28) For example, supercapacitors require the electrode material to have as large an ion-accessible surface area as possible, and lignin-based carbon fibers fabricated by electrospinning have shown great potential. (29−35) Lai et al. studied the possibility of using electrospun lignin-based carbon fiber networks (CFNs) as supercapacitor electrodes in 2014. (30) With a lignin/poly(vinyl alcohol) (PVA) mass ratio of 70/30, a specific capacitance of 64 F g–1 was recorded for the electrode material. Later, with optimized lignin/PVA ratios and carbonization conditions, the specific capacitance was increased to approximately 240 F g–1 without the help of activation or metal oxides. (29) When alkaline activation was employed, a remarkable specific capacitance of 344 F g–1 was reported, and the hydrophilicity of the CFNs was also increased. (31)
However, the use of renewable carbon-rich lignin in electrochemical devices is still in the early stages of development. So far, most of the studies have focused on kraft lignin and organosolv lignin, primarily because of the wide availability of these two lignin sources. Recently, hydrolysis lignin extracted from biofuel production has also attracted the attention of researchers because the chemical composition of hydrolysis lignin is more similar to that of the millwood lignin (MWL) than to those of lignins derived from chemical extraction. (36,37) In addition, a large stock of hydrolysis lignin has been produced by the biorefinery industry. High-value applications of the hydrolysis lignin can additionally increase the economic feasibility of the biofuel production. (38) The variation in chemical structure among different functional lignins raises uncertainties in the choice of the raw material for CFN preparation, which has not been comprehensively investigated and reported in the literature. Therefore, in this study, we prepared CFNs from kraft (KR), lignoboost (LB), hydrolysis (HY), and soda (SD) lignin and used them as electrodes in supercapacitors via electrospinning and direct carbonization. Characteristics such as the chemical structure and molecular size of different lignins were elucidated prior to the analysis of the electrochemical properties of the lignin-based CFNs. Furthermore, the effects of the orientation of the CFN structure on the electrochemical behaviors have also been investigated, which brings new opportunities for effectively enhancing the electrochemical performance of lignin-based CFNs.

Results and Discussion

Click to copy section linkSection link copied!

Some of the fundamental properties of the functional lignins were analyzed prior to the preparation of the CFNs. Figure 1a shows the 1H NMR spectra of the solutions of LB, KR, HY, and SD dissolved in DMSO-d6. These 1H NMR spectra are characteristic of different types of lignins previously studied by NMR spectroscopy, as described in detail in a review article by Ralph and Landucci. (39) The stereochemical complexity of lignin macromolecules causes dramatic broadening of J-multiplets for different chemical groups due to the severe overlapping of NMR signals. Despite the fact that one-dimensional 1H NMR spectra of lignins are predominantly featureless, the NMR signals can be assigned to groups, shown briefly in Figure 1a. (39−42) All lignins tested showed contributions from the Cβ protons in β–β and β-1 bonds (2.1–2.8 ppm) and from protons in COOCH3 and OCH3 groups (3.5–4.0 ppm). As the structure of HY was similar to the structure of the MWL, which is a functional lignin that preserves most of the chemical structure of lignin in the biomass, one could clearly see resonance lines at 0.4–1.6 ppm from protons in aliphatic CH3 and CH2 and at 6.3–8.2 ppm from aromatic protons. SD possessed fewer of these protons, and there were no detectable aliphatic protons in LB and KR, indicating that soda pulping was a milder chemical extraction method and preserved the lignin structure better than the kraft-pulping process. In the HY spectrum, a narrow resonance line at ca. 5.3 ppm was also observed. Protons in CHO of Cβ in β-5 and α-O-4 bonds were believed to be present here.

Figure 1

Figure 1. (a) 400.27 MHz 1H NMR spectra of LB, KR, HY, and SD dissolved in DMSO-d6. The 1H NMR resonance line at 2.50 ppm present in all the spectra corresponds to the solvent DMSO-d5(H). Assignment of protons in (i) CH2, CH3; (ii) CH2, CH; (iii) CH, CH3O, CH2O, CHO; (iv) aromatic H; (v) aromatic OH; and (vi) COOH. (b) 100.64 MHz 13C CP-MAS NMR spectra of LB, KR, HY, and SD. The MAS frequency was 8 kHz.

Solid-state 13C CP-MAS NMR experiments were performed to obtain deeper insights into the chemical structures of these samples, which were not fully revealed through the solution 1H and 13C NMR experiments (Figure S1 in the Supporting Information) due to the slow mobility of the larger polymer molecules. The 13C CP-MAS NMR spectra of the four lignins are shown in Figure 1b. The resonance line clusters in the 162–102 ppm range corresponded to the aromatic carbons in the lignins. Thus, the integral of this range could be selected as the internal standard to roughly quantify the relative content of aliphatic carbon (85–0 ppm), unsubstituted sp3 carbons (50–0 ppm), methoxyl carbons (approximately 56 ppm), and substituted sp3 (CO) carbons in carbohydrates (approximately 74 ppm). (43−45) It should be noted that this analysis was semiquantitative because the integral intensities of different carbon resonances depend on the number of nearby protons and the cross-polarization efficiency of the spin magnetization from protons to carbons, which are different for the carbonyl/carboxyl, aromatic, and aliphatic carbon sites. However, one can compare the relative integral intensities for aromatic and aliphatic carbon groups between the different lignin samples because 13C CP-MAS NMR spectra were obtained under the same experimental conditions. The results are shown in Table 1. Comparing the data for different lignin samples, it can be concluded that HY and SD had higher unsubstituted sp3 carbon ratios compared to the KR and LB samples, and the unsubstituted sp3 carbons were generally present in the MWL but were removed to a higher extent in the chemical extraction process. (46) Moreover, SD had the highest contribution from the resonance lines at approximately 74 ppm, which was attributed to the substituted sp3 (CO) carbons in carbohydrates that were not completely removed during the pulping process. Therefore, this semiquantitative analysis suggests that HY and SD had considerably higher overall ratios of aliphatic to aromatic carbons than KR and LB. Note that for a direct quantitative analysis of different carbon sites in lignin samples, one can use the direct excitation single-pulse 13C MAS NMR experiment. However, this would require significantly longer experiment times to obtain spectra with reasonably good signal-to-noise ratios because of the lower sensitivity and longer spin–lattice relaxation time of 13C sites.
Table 1. Relative 13C NMR Integral Intensities for Various Carbon Sites in the Powder Lignin Samples
ligninrelative integral intensitiesa
85–0 ppmb56 ppmc74 ppmd50–0 ppme
LB0.940.290.090.45
KR1.180.330.130.53
HY1.190.270.080.67
SD1.330.330.170.63
a

Normalized to the integral intensity of aromatic carbons (integrated in the range of 162–102 ppm).

b

All-aliphatic carbons.

c

Methoxyl carbons (integrated in the range of 60–50 ppm).

d

Substituted sp3 (CO) carbons, carbohydrates (integrated in the range of 77–67 ppm).

e

Unsubstituted sp3 carbons.

The molecular weight and polydispersity index of LB, SD, and HY, determined by gel permeation chromatography, are listed in Table 2. The molecular size distribution is shown in Figure S2 (Supporting Information). Based on the molecular structure, LB had the highest number-average molecular weight (Mn) and a more uniform polydispersity index (PDI), making it more suitable for electrospinning. On the other hand, since SD was extracted from annual herbs, such as straw or grass, its weight-average molecular weight (Mw) and Mn were the lowest among these three. Low Mw and Mn indicated small molecules and short molecular chains, which were not favorable for electrospinning. Approximately 90% of the HY molecules had a molecular weight in the range of 100–50 kDa, which was similar to SD (Figure S2c in the Supporting Inforamtion). However, approximately 10% of the molecules in HY were greater than 100 kDa and were probably preserved by the milder biochemical extraction process, leading to less degradation of the original aliphatic chains than occurs in the chemical extraction processes. These large molecules were more difficult to dissolve in aqueous solutions because of the slow and potentially hindered movement of the molecular chain and could cause clogging during the electrospinning process. Because KR could not be dissolved in the testing solvent, no information could be collected from the GPC. According to the information provided by the supplier, KR had an Mw of approximately 10 kDa. Considering the differences induced by the testing methods, KR and HY should have had similar Mw values.
Table 2. Weight Average Molecular Weight (Mw), Number Average Molecular Weight (Mn), and Polydispersity Index (PDI) of LB, SD, and HY
 Mw (Da)Mn (Da)PDI
LB42027415.57
KRaca. 10 000N.A.N.A.
SD22196013.69
HY736766411.1
a

According to the information from the supplier.

The thermal degradation of the lignin powders used in this study was examined using a thermogravimetric analyzer under a nitrogen atmosphere (Figure 2). LB, KR, and HY had primary degradation peaks at approximately 370 °C, but HY had more mass left when the temperature reached 900 °C due to the presence of larger molecules. SD started to soften and degrade from approximately 80 °C, and the softening of SD caused the loose lignin powder to condense to a compact solid, which could be detrimental to the formation of porous material during carbonization. We could also find a clear relationship between the Mw and the mass left at 900 °C when comparing Figure 2 and Table 2. Therefore, we can again confirm that KR and HY should have similar Mw.

Figure 2

Figure 2. Thermogravimetric analysis of LB, KR, HY, and SD in N2 atmosphere.

Figure 3 shows optical microscopy images of the lignin solutions, optimized for electrospinning. LB, KR, and HY could be dissolved easily, whereas insoluble particles were observed in the SD solution. These particles were attributed to the higher amount of ash in the sample as reported in another study. (47) The magnified image shown in Figure S3 (Supporting Informaton) indicates that there are also some small intact plant cells from the feedstock which were not filtered out. Impurities could make the electrospinning process unstable, but fibers from SD were successfully electrospun even with the aforementioned obstacles.

Figure 3

Figure 3. Optical microscopy image of the (a) LB, (b) KR, (c) HY, and (d) SD solutions used for preparing the electrospinning precursor.

During the electrospinning process, a rotational collector placed 20 cm away from the spinning tip was used to retrieve the electrospun fibers and form the fiber networks (Figure S4). The fiber networks were coded according to the type of lignin used, the rotation speed of the collector, and the post-treatment condition. An explanation of the sample codes is shown in Table 3. When the collector had a rotational speed of 200 rpm during the electrospinning process, the as-spun fiber networks, consisting of randomly oriented fibers with diameters of approximately 350 nm, were collected for all four lignins, as shown in Figure S5. The colored scanning electron microscope (SEM) images of the networks (Figure S6) reveal that LB200, KR200, HY200, and SD200 are randomly oriented under these conditions. After carbonization, the random orientation and the similarity in diameters remained for the C-LB200, C-KR200, C-HY200, and C-SD200 samples, and the fiber diameter decreased to approximately 200 nm (Figure 4 and Figure 5). Moreover, it can be clearly seen from Figure 4 that the obtained carbon fibers are long and continuous, which endows the fiber networks with flexibility and shape stability. The flexibility showcases of the CFNs made from KR have already been illustrated in our previous study. (29)
Table 3. Sample Codes Used in This Study
sample codeligninspeed of the collector (rpm)carbonization
LB200LB200no
KR200KR200no
HY200HY200no
SD200SD200no
LB1500LB1500no
C-LB200LB200yes
C-KR200KR200yes
C-HY200HY200yes
C-SD200SD200yes
C-LB1500LB1500yes

Figure 4

Figure 4. SEM images and the fiber diameter distributions of (a) C-LB200, (b) C-KR200, (c) C-HY200, and (d) C-SD200.

Figure 5

Figure 5. Orientation-related colored SEM images of (a) C-LB200, (b) C-KR200, (c) C-HY200, and (d) C-SD200. Zero degree corresponds to the vertical direction.

The chemical composition of the CFNs from energy dispersive X-ray spectroscopy (EDX) is shown in Table 4, where it is seen that carbon dominates in C-LB200, C-KR200, C-HY200, and C-SD200 with slight variations in the exact quantities. The presence of oxygen indicated the presence of oxygen-containing functional groups in the CFNs, which may have affected their electrochemical properties. In addition, a smaller share of sodium, sulfur, and potassium was detected in these carbon fibers. These elements were introduced into the fibers either by the chemicals used in the lignin extraction process or from the ash contained in the lignin powder. The addition of NaOH during the preparation of the electrospinning solutions also increased the sodium content in C-LB200, C-HY200, and C-SD200.
Table 4. Elemental Compositions of the CFNs Based on the SEM-EDX Measurements, Specific Surface Area (SSA), and Adsorption Average Pore Size
 SEM-EDX  
sampleC (at. %)O (at. %)Na (at. %)S (at. %)K (at. %)SSA (m2 g–1)pore sizea (nm)
C-LB20093.35.40.60.70.07151.7
C-KR20095.73.40.20.40.112411.8
C-HY20093.95.20.20.70.012682.2
C-SD20096.42.70.50.40.212862.2
C-LB150095.43.40.60.50.07001.7
a

Adsorption average pore diameter (4 V/A by BET).

Figure 6 shows the visible Raman spectra of the unoriented CFNs. In agreement with the EDX results, characteristic peaks of carbon materials, that is, the D peak at ca.1350 cm–1 and G peak at ca.1580 cm–1, were observed. From the visible Raman spectra, both the D and G peaks could be attributed to the sp2 sites in the carbon material. The sp2 atoms in either rings or chains could give rise to the appearance of the G peak, while only defects in rings containing sp2 atoms could activate the D peak. (48) According to a study by Ferrari and Robertson, (49) one can conclude that all these CFNs were nanocrystalline graphite with topological disorder because in every spectrum (i) the G peak lies between ca.1510 and 1600 cm–1, (ii) the intensity ratio between the corresponding D peak and G peak was less than 2, and (iii) instead of a well-defined peak, there was a small bump from ca. 2300 to 3000 cm–1. In our previous study, TEM images of similar materials also confirmed the conclusions drawn from the Raman spectra. (50)

Figure 6

Figure 6. Raman spectra of C-LB200, C-KR200, C-HY200, and C-SD200.

The electrochemical performance of the CFNs was tested in a three-electrode cell using Pt as the counter electrode and Ag/AgCl in 3.0 M KCl as the reference electrode. The electrolyte used was 1 M H2SO4. Cyclic voltammetry (CV) curves, galvanostatic charge–discharge (GCD) profiles, specific capacitance from the GCD, and the cycle stability of the randomly oriented CFNs are summarized in Figure 7 and Figure S7. It is obvious that all the randomly oriented CFNs exhibited capacitive and quasi-rectangular CV curves. Rounding of the corners of the CVs and the CV tilting from the horizontal were caused by the Faradaic resistance and the equivalent series resistance (ESR), respectively. (51) There were also reversible minor bumps, which could be attributed to a small amount of pseudocapacitance induced by oxygen-containing groups. (52) Despite the similarities in fiber diameters and carbon structure, the areas covered by the curves and the shape of the curves varied from the functional lignins used to prepare the CFNs. Sample C-SD200 had CV curves that were the closest to rectangles, while C-LB200 could store the most energy under the same circumstances (Figure 7a and Figure S7).

Figure 7

Figure 7. Electrochemical properties of the randomly oriented CFNs. (a) Cyclic voltammograms (CV) of C-LB200, C-KR200, C-HY200, and C-SD200 under a scan rate of 100 mV s–1. (b) Galvanostatic charge–discharge (GCD) profiles of C-LB200, C-KR200, C-HY200, and C-SD200 using a current density of 10 A g–1. (c) Summary of the specific capacitance of C-LB200, C-KR200, C-HY200, and C-SD200 from the GCD under a series of current density. (d) Capacitance retention of C-LB200, C-KR200, C-HY200, and C-SD200 during 10 000 charge–discharge cycles under a current density of 10 A g–1.

A similar tendency was observed in the GCD profiles (Figure 7b and Figure S8), and the gravimetric specific capacitance of the electrode (Celec) under a series of scan rates was calculated using eq 2 and is summarized in Figure 7c. C-LB200 had Celec of 456.1, 376.3, 303,3, 256.5, 211.3, and 182.0 F g–1 when discharged at current densities of 1, 2, 5, 10, 20, and 30 A g–1, respectively, which was the highest Celec among all the randomly oriented CFNs under the corresponding current density. Table 5 compares the Celec of C-LB200 with other reported lignin-based electrospun CFNs, and C-LB200 shows outstanding capability to store energies under a current density of 1 A g–1. Seventy-one percent of the Celec was retained when the current density increased from 10 to 30 A g–1. C-KR200 had a slightly lower Celec when the current density was low (439 F g–1 at 1 A g–1), but it lost its capacitance much faster with the increase in the current density compared to other CFNs. Although C-HY200 had a moderate Celec compared to C-LB200, its performance was still in a similar range. Notably, although C-SD200 had the lowest Celec when the scan rate was less than 10 A g–1, the decrease in Celec as the current density increased from 10 to 30 A g–1 was less prominent, with approximately 80% Celec being retained. Moreover, the cycle stability of all CFNs was analyzed after 10 000 GCD runs using a current density of 10 A g–1. C-HY200 and C-SD200 exhibited good cycle stability. After 10 000 cycles, almost 100% of the initial Celec was retained. However, despite the outstanding Celec values of C-LB200 and C-KR200 at 1 A g–1, only 73.6% and 70.4% of the initial Celec values were obtained after 10 000 cycle runs, respectively. Besides, the shape and flexibility of the electrodes can be maintained after the entire electrochemical test procedures (Figure S9).
Table 5. Comparison of the Celec of the Lignin-Based CFNs Reported in This Study and Other Literature
precursor materialscell configurationelectrolytecurrent density (A g–1)Celec (F g–1)ref
modified lignin/polyacrylonitrilethree-electrode6 M KOH1428.9 (53)
kraft lignintwo-electrode6 M KOH0.1155 (54)
kraft lignin/poly(vinylpyrrolidone)/Zn(NO3)2three-electrode6 M KOH0.1217 (55)
20152
hydrolyzed lignin/polyacrylonitrile/poly(methyl methacrylate)three-electrode6 M KOH0.5233 (56)
kraft lignin/PVAtwo-electrode6 M KOH0.8179.2 (29)
kraft lignin/PVAtwo-electrode6 M KOH0.464 (30)
lignoboost lignin/PVAthree-electrode1 M H2SO41456.1this study
To understand the differences in the capacitance, the BET specific surface areas (SSAs) of the CFNs were analyzed using N2 at 77 K, and the results are listed in Table 4. The N2 adsorption isotherms and the pore size distribution of the samples can be found in Figures S10 and S11 (Supporting Information). C-KR200, C-HY200, and C-SD200 have similar SSAs of approximately 1250 m2 g–1 while C-LB200 only had an SSA of 715 m2 g–1. The capacitance of a material is proportional to its surface area, which is accessible to the electrolyte ions. In this study, however, even though C-LB200 had the least BET-detectable SSA, it had the highest capacitance at all current densities. One possible reason is that the detected SSA in C-KR200, C-HY200, and C-SD200 is less accessible to the electrolyte ions than the one in C-LB200. Moreover, there were many other factors controlling the electrochemical behavior of the materials, such as the conductivity, pore shape, and surface chemistry of the electrode. As the NMR results revealed, the chemical structures of these four functional lignins were significantly different. These structural differences lead to, for example, various pore formation processes and different carbon structures. The relationships between the structural differences revealed by NMR and the electrochemical performance of the corresponding lignin-based CFNs are not significant. Thus, computational simulation of both the carbonization process (especially the pore formation reactions and the final pore structure) and the charge–discharge behavior of the electrode, which can provide a clearer and more comprehensive picture of understanding these properties, should be done in future studies.
Considering the electrochemical performance of the randomly oriented CFNs and the difficulties in electrospinning, LB was chosen as the lignin for oriented CFN preparation. Kim et al. reported that increasing the rotational speed of the collector led to the orientation of the electrospun polyacrylonitrile (PAN) fibers along the rotating direction, and the electrochemical properties of the PAN-based CFNs were enhanced with increasing fiber orientation. (57) Therefore, the rotational speed of the collector was set to 1500 rpm, which was close to its maximal speed, to collect the oriented fiber networks. A comparison of the fiber morphologies is shown in Figure 8. The oriented fiber networks LB1500 and C-LB1500 had similar fiber diameters to their counterparts, that is, LB200 and C-LB200, respectively. The orientation-related colored SEM images (Figure 9) clearly show that the fibers in LB1500 and C-LB1500 are preferably oriented along the rotational direction of the collector (i.e., the vertical direction in the images). The orientation distribution of LB1500 is shown in Figure 9c, and its orientation index, fc, was calculated to be 0.81, which was much higher than that of LB200. Figure 9f also reveals that the carbonization process does not affect the orientation of the CFNs, and the fc of C-LB1500 was 0.87.

Figure 8

Figure 8. Fiber morphology of the as-spun and the carbonized fiber networks. (a) SEM image of LB200, (b) SEM image of LB1500, (c) fiber diameter distribution of LB200 and LB1500, (d) SEM image of C-LB200, (e) SEM image of C-LB1500, and (f) fiber diameter distribution of C-LB200 and C-LB1500.

Figure 9

Figure 9. Orientation-related colored SEM images of (a) LB200, (b) LB-1500, (d) C-LB200, and (e) C-LB1500. Orientation distribution graphs of (c) LB200 and LB1500 and (f) C-LB200 and C-LB1500. Zero degree is aligned to the vertical direction.

The results in Table 4 show that the orientation of the fibers in C-LB1500 has no significant effect on the SSA compared to the unoriented one (C-LB200). A slight increase in the carbon content can be ascribed to the shorter diffusion path during the elimination of elements when there was a more organized fiber structure. However, the orientation of the CFNs had a positive impact on the electrochemical properties (Figure 10). Because of the decrease in the amount of noncarbon elements, the pseudocapacitance induced by other functional groups decreased significantly in C-LB1500 (Figure 10a and 10c). Moreover, the Celec values of C-LB1500 calculated from the GCD curves were 529.1, 428.0, 344.0, 291.2, 238.0, and 203.5 F g–1 at current densities of 1, 2, 5, 10, 20, and 30 A g–1, respectively, which were higher than those of C-LB200 (Figure 10b, 10d, and 10e). In addition, the cycle stability of the CFNs made from LB was significantly increased by the orientation of the fibers (Figure 10f). C-LB1500 retained more than 95.0% capacitance after 10 000 GCD tests at a current density of 10 A g–1, compared to C-LB200 which retained 70.6% capacitance. The EIS tests (Figure 11) suggested that although the orientation of the CFNs increased the resistance of the charge transport of the electrode (proportional to the diameter of the semicircles), probably owing to less intercontact of the fibers in the oriented CFNs, a more organized network structure should decrease the electrolyte ion diffusion resistance, (51,58,59) which made C-LB1500 capable of storing more energy and gave it a longer service life.

Figure 10

Figure 10. Comparison of the electrochemical properties between the randomly oriented and highly oriented CFNs. (a) CV of C-LB1500. (b) GCD of C-LB1500. (c) CV of C-LB200 and C-LB1500 under a scan rate of 100 mV s–1. (d) GCD curves of C-LB200 and C-LB1500 using a current density of 10 A g–1. (e) Summary of the specific capacitance of C-LB200 and C-LB1500 from the GCD under a series of current densities. (f) Capacitance retention of C-LB200 and C-LB1500 during charge–discharge cycles under a current density of 10 A g–1.

Figure 11

Figure 11. Nyquist diagrams for C-LB200 and C-LB1500 obtained using electrochemical impedance spectroscopy (EIS). The testing potential is 300 mV.

Conclusion

Click to copy section linkSection link copied!

This study compared four functional lignins, i.e., lignoboost (LB), kraft (KR), hydrolysis (HY), and soda (SD) lignin, examining their chemical structures and exploring the electrochemical properties of the electrospun carbon fiber networks (CFNs) made from these lignins. According to the solution 1H and solid-state 13C NMR data, the chemical composition of the carbon and hydrogen sites varied among these functional lignins. In the less-process-affected HY and SD, higher ratios of aliphatic to aromatic carbons were observed, and SD even had a considerable amount of substituted sp3 CO carbon sites (carbohydrates), which may have negatively affected the electrospinning process. These differences in the chemical structure also resulted in different electrochemical performances in the derived electrospun CFNs, despite the CFNs having similar fiber diameters and chemical compositions. For the randomly oriented CFNs, C-LB200 exhibited the best specific capacitance under all current densities used. The performance of C-KR200 was almost as good as that of C-LB200 when the current density was low (1 A g–1). However, among these samples, it lost its capacitance the fastest when the current density increased. Moreover, C-HY200 and C-SD200 were able to retain almost 100% of their capacities after 10 000 charge/discharge cycles, while C-LB200 and C-KR200 could only keep approximately 70% of their capacitance after the cycle stability test. In addition, by simply increasing the rotational speed of the collector during electrospinning, highly oriented CFNs from LB (C-LB1500) with an orientation index of 0.87 could be fabricated. Compared to C-LB200, the orientation of the fibers enhanced not only the specific capacitance by approximately 15% but also the cycle stability of the CFNs to approximately 95%. Thus, we would also suggest orienting the fibers when making such electrodes to further increase their electrochemical performance.

Experimental Section

Click to copy section linkSection link copied!

Materials

Kraft lignin (alkali, low sulfonate content, Mw of ca. 10 000) was purchased from Sigma-Aldrich. Nonwood soda lignin (Protobind 2000, ALM Private Limited, Indulin AT, India) and pine lignoboost lignin (Biochoice, Domtar Plymouth pulp mill, USA) were kindly provided by the Centre for Biocomposites and Biomaterials Processing at the University of Toronto. Hydrolysis lignin was kindly provided by St1, a Finnish energy company, having a St1 Cellunolix process at the Kajaani plant, Finland. The raw material for HY was pine and/or spruce softwood sawdust. The sawdust was first pretreated in a steam explosion reactor, followed by enzymatic hydrolysis to release the monosugars for ethanol fermentation. After the enzymatic hydrolysis, the suspension was filtered, and solid filter cakes containing HY were sent to us for further purification. The as-received filter cake was purified using the following steps: (i) the filter cake was dissolved in 2 wt % NaOH for 4 h; (ii) the insoluble particles were filtered out using filter paper with a pore size between 5 and 13 μm; (iii) the pH of the filtered solution was tuned by gradually adding 3.5 M HCl until the HY precipitated; (iv) purified HY was filtered from the suspension using a PP filter with a pore size of 0.45 μm and dried. The yield of the purified HY was approximately 15%.
Poly(vinyl alcohol) (PVA, Mw of 89 000–98 000, ≥99% hydrolyzed), sodium hydroxide (NaOH, pellets), sulfuric acid (H2SO4, 98%), and hydrochloric acid (HCl, 36%) were purchased from Sigma-Aldrich and used without any further purification.

Electrospinning of Lignin-Based Fibers

First, the PVA and lignin solutions were prepared separately. A set quantity of PVA powder was added to distilled water to make the solid content 20 wt % and heated to 85 °C with continuous stirring for 2 h. The warm, clear PVA solution was allowed to cool to room temperature before being mixed with different lignin solutions. To prepare the lignin solutions, lignin powder was added to distilled water, and the mixture was stirred at room temperature for 1 h. An appropriate amount of NaOH was added when necessary to dissolve the lignin. PVA and lignin solutions were mixed (lignin/PVA weight ratio = 75/25) at room temperature for 30 min. Distilled water was added to tune the total solid content, if required. The compositions of the different lignin/PVA solutions are listed in Table 6. It is noteworthy that although no extra NaOH was added to the KR-containing precursor, according to our previous study, there was already approximately 7 wt % sodium contributed to the dry weight of the precursor, introduced by KR. (29) Thus, the effects of sodium in these four precursors during electrospinning and carbonization should be similar. (60,61)
Table 6. Chemical Composition of the Precursors and the Settings for Electrospinning
 LBKRHYSD
solid contenta (wt %)16191619
lignin (g)3.03.33.03.6
PVAb (g)1.01.11.01.2
H2O (g)20.719.020.720.0
NaOH (g)0.30.00.30.3
pH11.38.711.210.6
voltage (kV)16.016.020.020.0
feeding rate (8 mL h–1)0.400.200.450.25
a

Only PVA and lignin contributed to the solid content in the calculation.

b

PVA is a commonly used binder polymer to facilitate the electrospinning of lignin-dominated precursor. According to the study from Ago et al., (62) a continuous phase of lignin has been found on surfaces of the electrospun fibers using this lignin/PVA ratio. Lai et al. (30) reported that pure PVA fibers formed less porous carbon with a low degree of graphitic order when carbonized.

The newly prepared lignin/PVA solutions were electrospun using a Fluidnatek LE-10 electrospinning setup (Bioinicia SL, Spain). A 12 mL syringe (HSW NORM-JECT, Henke-Sass, Bremen, Germany) was used as a solution supplier, and a poly(tetrafluoroethylene) (PTFE) pipe with an outer diameter of 1/8 in. formed the connection between the syringe and the spinning nozzle (inner diameter 0.6 mm). A rotating collector placed 20 cm away from the nozzle was used to collect the fibers and build networks. The rotational speed was set to 200 and 1500 rpm to collect randomly oriented and highly oriented fiber networks, respectively. An illustration of the electrospinning setup is shown in Figure S4 (Supporting Information), and the feeding rate as well as the applied voltage for different lignin/PVA solutions is provided in Table 6.

Carbonization of the As-Spun fFbers

The as-spun lignin/PVA fiber networks were directly carbonized in a ceramic boat in a Nabertherm RHTC-230/15 tube furnace (Nabertherm GmbH, Lilienthal, Germany) under a constant nitrogen flow. The carbonization program included a heating step with a heating rate of 5 °C/min followed by an isothermal step at 1000 °C for 1 h.

Characterization

The solution 1H and 13C NMR spectra of the lignin samples (in DMSO-d6) were obtained using a Bruker Avance III NMR spectrometer (Bruker BioSpin AG, Fällanden, Switzerland) with an Aeon 9.4 T zero-helium boil-off superconducting magnet using 10 and 5 mm probes for the liquids. Working frequencies were 400.27 and 100.64 MHz for 1H and 13C, respectively. The 1H π/2 pulse duration and recycling time were 9 μs and 1 s, respectively. Solid-state 13C cross-polarization magic-angle-spinning (CP-MAS) NMR spectra for powder lignin samples were obtained at 100.64 MHz on the same NMR spectrometer using a Varian 4.0 mm MAS probe. Masses ranging from approximately 70 mg (for KL) to 107 mg (for SD) were tightly packed as a fine powder in a thin-wall 4.0 mm ZrO2 rotor. The density of the lignin samples varied by more than 50% because the same sample volume in the rotor was used for all measurements. Cross-polarization from the protons, together with a phase-modulated proton decoupling for the suppression of 13C–1H interactions using the radio frequency field at the proton resonance frequency (400.21 MHz), were applied. (63) The proton π/2 pulse duration and the CP contact time were 3.3 μs and 2.0 ms, respectively. For different lignin samples from 668 to 2038 signal transients spaced by a relaxation delay of 2.0 s were accumulated in each NMR experiment performed at a spinning frequency of 8.0 kHz. Isotropic 13C chemical shifts (in the deshielding, δ-scale) were externally referenced to the least shielded resonance line of solid adamantane (64) (at 38.48 ppm relative to tetramethylsilane (65)). The drift in the 13C frequency (B0-drift) was 0.025 Hz·h–1. The 13C NMR spectra were recorded at ambient temperature (approximately 293 K). The homogeneity of the magnetic field was monitored after shimming the Varian 4 mm MAS probe by measuring the line width at the half-height of the reference signal of crystalline adamantane at δ(13C) = 38.48 ppm, which was adjusted to less than 15 Hz at a custom limited acquisition time of FID of 50 ms as a default value for the Bruker 4 mm MAS NMR probes. The molecule size distributions of LB, SD, and HY were analyzed by gel permeation chromatography (GPC) using an Agilent 1260 high-performance liquid chromatograph (HPLC, Agilent Technologies, Inc., Santa Clara, CA) equipped with three 5 μm Phenogel HPLC columns (Phenomenex Inc., Torrance, CA). The powdered samples were dissolved in DMF with 0.05 wt % LiBr to an approximate concentration of 1 g L–1. Poly(ethylene glycol) standards were used to estimate the molar masses from the retention time data. The thermal stability of KR, LB, SD, and HY was analyzed using a TA Q500 thermogravimetric analyzer (TA Instruments, New Castle, USA) under a nitrogen atmosphere to 900 °C at a heating rate of 10 °C min–1. Lignin solutions were first observed under a Nikon Eclipse LV100 POL optical microscope (Kanagawa, Japan) prior to mixing with PVA solutions. SEM (Magellan 400 XHR-SEM, FEI Company, Hillsboro, OR) was used to investigate the structures of the as-spun and carbonized fiber networks. The as-spun networks were coated with platinum (Bal-Tec MED 020, Leica, Wetzlar, Germany). ImageJ was used to measure the fiber diameter. (66) More than 100 fibers from at least five different areas were chosen for measurement, and the average values were calculated. Orientation properties of the fiber networks were characterized by OrientationJ, a series of plugins for ImageJ. (67) The orientation index (fc) of the fiber networks was calculated using the following equation: (68)
(1)
where fwhm is the full width at half-maximum of the orientation distribution. The composition of the CFNs was studied by SEM (JEOL JSM 6460LV, JEOL Ltd., Tokyo, Japan) with a silicon drift detector (Oxford X-MaxN 50 mm2, Oxford Instruments, Oxfordshire, U.K.). The CFNs were attached to an aluminum sample holder using carbon tape. A proper sample thickness was ensured to prevent the electron beams from reaching the carbon tape. A Gemini VII 2390a surface area analyzer (Micromeritics Instrument Corp., Norcross, GA) was used for the surface area measurements. The samples were degassed at 573 K for 3 h prior to the measurement. Surface area analysis was performed by feeding nitrogen at 77 K. The carbon structure of the CFNs was analyzed using a Bruker Senterra dispersive Raman spectroscope (Bruker Corp., Billerica, MA). A laser beam with a wavelength of 533 nm and a power of 2 mW was used. Signals from 128 runs were integrated to obtain the final results. A low-volume three-electrode cell kit (Pine Research Instrumentation, Durham, NC) was connected to a VersaSTAT 3 potentiostat/galvanostat (Princeton Applied Research, Oak Ridge, TN) for the electrochemical tests. CFNs with dimensions of approximately 10 mm × 5 mm × 20 μm were attached to the sample holder as a working electrode. Ag/AgCl in 3 M KCl was used as the reference electrode, and Pt was used as the counting electrode. These three electrodes were immersed in an appropriate amount of a 1 M H2SO4 electrolyte. The specific capacitance of the material (Celec) was calculated using the following equation: (29)
(2)
where I is the source current, ΔV is the measured voltage window, Δt is the discharge time, and m is the mass of the electrode.

Supporting Information

Click to copy section linkSection link copied!

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acssuschemeng.1c03549.

  • 13C NMR spectra of lignins; molecule size distribution of lignins; magnified OM image of SD solution; illustration of the electrospinning setup; SEM images of as-spun fiber networks; CV plots and GCD curves of CFNs; bending test of the electrode after the electrochemical testing; N2 adsorption isotherms of the CFNs at 77 K; pore size distribution of the CFNs based on nonlocal density functional theory (PDF)

Terms & Conditions

Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.

Author Information

Click to copy section linkSection link copied!

  • Corresponding Author
    • Kristiina Oksman - Department of Engineering Sciences and Mathematics and , Luleå University of Technology, SE-97187 Luleå, SwedenMechanical & Industrial Engineering (MIE), University of Toronto, Toronto, ON M5S 3G8, CanadaOrcidhttps://orcid.org/0000-0003-4762-2854 Email: [email protected]
  • Authors
    • Jiayuan Wei - Department of Engineering Sciences and Mathematics and , Luleå University of Technology, SE-97187 Luleå, SwedenOrcidhttps://orcid.org/0000-0002-1484-7224
    • Faiz Ullah Shah - Chemistry of Interfaces and , Luleå University of Technology, SE-97187 Luleå, SwedenOrcidhttps://orcid.org/0000-0003-3652-7798
    • Lisa Johansson Carne - Department of Engineering Sciences and Mathematics and , Luleå University of Technology, SE-97187 Luleå, Sweden
    • Shiyu Geng - Department of Engineering Sciences and Mathematics and , Luleå University of Technology, SE-97187 Luleå, SwedenOrcidhttps://orcid.org/0000-0003-1776-2725
    • Oleg N. Antzutkin - Chemistry of Interfaces and , Luleå University of Technology, SE-97187 Luleå, Sweden
    • Mohini Sain - Mechanical & Industrial Engineering (MIE), University of Toronto, Toronto, ON M5S 3G8, CanadaOrcidhttps://orcid.org/0000-0003-0808-271X
  • Author Contributions

    Conceptualization, data curation, formal analysis, investigation, methodology, validation, visualization, writing–original draft, and writing–review and editing (J.W.); data curation, formal analysis, investigation, methodology, validation, writing–original draft, and writing–review and editing (F.U.S.); investigation (L.J.C.); data curation, formal analysis, investigation, and writing–review and editing (S.G.); data curation, formal analysis, investigation, validation, writing–original draft, and writing–review and editing (O.N.A.); resources, supervision, and writing–review and editing (M.S.); conceptualization, funding acquisition, project administration, resources, supervision, and writing–review and editing (K.O.).

  • Notes
    The authors declare no competing financial interest.

Acknowledgments

Click to copy section linkSection link copied!

The authors acknowledge the Swedish Research Council (Carbon Lignin 2017-04240), Swedish Strategic Research Program Bio4Energy, and Business Finland (Grelectronics) for their financial support. St1 Oy (Helsinki, Finland) is acknowledged for providing the hydrolysis lignin. We are thankful to Ms. Elisa Wirkkala at the University of Oulu for the purification of hydrolysis lignin. Dr. Manish Kumar and the Chemical Process Engineering Research Unit at the University of Oulu are acknowledged for conducting the GPC test. We also thank the Kempe Foundation in memory of J. C. and Seth M. Kempe (project numbers JCK-1306 and JCK-1433) and the laboratory fund at Luleå University of Technology (LTU) for providing grants, from which a Bruker Aeon/Avance III NMR spectrometer at LTU was purchased.

References

Click to copy section linkSection link copied!

This article references 68 other publications.

  1. 1
    Bajpai, P. Lignin. In Carbon Fibre from Lignin; Springer Nature: Singapore, 2017; pp 1115.
  2. 2
    Henriksson, G. Lignin. In Wood chemistry and biotechnology; Ek, M., Gellerstedt, G., Henriksson, G., Eds.; Pulp and Paper Chemistry and Technology; Walter de Gruyter GmbH & Co.: Berlin, Germany, 2009; Vol. 1, pp 121145.
  3. 3
    Yuan, T.-Q.; Sun, S.-N.; Xu, F.; Sun, R.-C. Characterization of Lignin Structures and Lignin–Carbohydrate Complex (LCC) Linkages by Quantitative 13C and 2D HSQC NMR Spectroscopy. J. Agric. Food Chem. 2011, 59 (19), 1060410614,  DOI: 10.1021/jf2031549
  4. 4
    Gierer, J. Chemical Aspects of Kraft Pulping. Wood Sci. Technol. 1980, 14 (4), 241266,  DOI: 10.1007/BF00383453
  5. 5
    Gosselink, R. J. A. Lignin as a Renewable Aromatic Resource for the Chemical Industry . Ph.D. Thesis, Wageningen University, Wageningen, Netherlands, 2011.
  6. 6
    Chakar, F. S.; Ragauskas, A. J. Review of Current and Future Softwood Kraft Lignin Process Chemistry. Ind. Crops Prod. 2004, 20 (2), 131141,  DOI: 10.1016/j.indcrop.2004.04.016
  7. 7
    Henriksson, G.; Li, J.; Zhang, L.; Lindström, M. Lignin Utilization. In Thermochemical Conversion of Biomass to Liquid Fuels and Chemicals; Crocker, M., Ed.; RSC Energy and Environment Series; Royal Society of Chemistry: London, 2010.
  8. 8
    Lora, J. H. Lignin: A Platform for Renewable Aromatic Polymeric Materials. Quality Living Through Chemurgy and Green Chemistry; Springer: Berlin, Heidleberg, Germany, 2016; pp 221261.
  9. 9
    Biermann, C. J. Handbook of Pulping and Papermaking; Academic Press: Cambridge, MA, 1996.
  10. 10
    Chapple, C.; Ladisch, M.; Meilan, R. Loosening Lignin’s Grip on Biofuel Production. Nat. Biotechnol. 2007, 25 (7), 746748,  DOI: 10.1038/nbt0707-746
  11. 11
    Raud, M.; Tutt, M.; Olt, J.; Kikas, T. Dependence of the Hydrolysis Efficiency on the Lignin Content in Lignocellulosic Material. Int. J. Hydrogen Energy 2016, 41 (37), 1633816343,  DOI: 10.1016/j.ijhydene.2016.03.190
  12. 12
    Ragauskas, A. J.; Beckham, G. T.; Biddy, M. J.; Chandra, R.; Chen, F.; Davis, M. F.; Davison, B. H.; Dixon, R. A.; Gilna, P.; Keller, M. Lignin Valorization: Improving Lignin Processing in the Biorefinery. Science 2014, 344, 6185,  DOI: 10.1126/science.1246843
  13. 13
    Fache, M.; Boutevin, B.; Caillol, S. Vanillin Production from Lignin and Its Use as a Renewable Chemical. ACS Sustainable Chem. Eng. 2016, 4 (1), 3546,  DOI: 10.1021/acssuschemeng.5b01344
  14. 14
    Culebras, M.; Sanchis, M. J.; Beaucamp, A.; Carsí, M.; Kandola, B. K.; Horrocks, A. R.; Panzetti, G.; Birkinshaw, C.; Collins, M. N. Understanding the Thermal and Dielectric Response of Organosolv and Modified Kraft Lignin as a Carbon Fibre Precursor. Green Chem. 2018, 20 (19), 44614472,  DOI: 10.1039/C8GC01577E
  15. 15
    Jiang, W.; Liu, S.; Wu, C.; Liu, Y.; Yang, G.; Ni, Y. Super-Stable, Solvent-Resistant and Uniform Lignin Nanorods and Nanospheres with a High Yield in a Mild and Facile Process. Green Chem. 2020, 22 (24), 87348744,  DOI: 10.1039/D0GC02887H
  16. 16
    Yang, Y.; Deng, Y.; Tong, Z.; Wang, C. Renewable Lignin-Based Xerogels with Self-Cleaning Properties and Superhydrophobicity. ACS Sustainable Chem. Eng. 2014, 2 (7), 17291733,  DOI: 10.1021/sc500250b
  17. 17
    Kai, D.; Zhang, K.; Jiang, L.; Wong, H. Z.; Li, Z.; Zhang, Z.; Loh, X. J. Sustainable and Antioxidant Lignin–Polyester Copolymers and Nanofibers for Potential Healthcare Applications. ACS Sustainable Chem. Eng. 2017, 5 (7), 60166025,  DOI: 10.1021/acssuschemeng.7b00850
  18. 18
    Wei, C.; Zhu, X.; Peng, H.; Chen, J.; Zhang, F.; Zhao, Q. Facile Preparation of Lignin-Based Underwater Adhesives with Improved Performances. ACS Sustainable Chem. Eng. 2019, 7 (4), 45084514,  DOI: 10.1021/acssuschemeng.8b06731
  19. 19
    Baker, D. A.; Rials, T. G. Recent Advances in Low-Cost Carbon Fiber Manufacture from Lignin. J. Appl. Polym. Sci. 2013, 130 (2), 713728,  DOI: 10.1002/app.39273
  20. 20
    Geng, S.; Wei, J.; Jonasson, S.; Hedlund, J.; Oksman, K. Multifunctional Carbon Aerogels with Hierarchical Anisotropic Structure Derived from Lignin and Cellulose Nanofibers for CO2 Capture and Energy Storage. ACS Appl. Mater. Interfaces 2020, 12 (6), 74327441,  DOI: 10.1021/acsami.9b19955
  21. 21
    Guo, N.; Li, M.; Sun, X.; Wang, F.; Yang, R. Enzymatic Hydrolysis Lignin Derived Hierarchical Porous Carbon for Supercapacitors in Ionic Liquids with High Power and Energy Densities. Green Chem. 2017, 19 (11), 25952602,  DOI: 10.1039/C7GC00506G
  22. 22
    Herou, S.; Ribadeneyra, M. C.; Madhu, R.; Araullo-Peters, V.; Jensen, A.; Schlee, P.; Titirici, M. Ordered Mesoporous Carbons from Lignin: A New Class of Biobased Electrodes for Supercapacitors. Green Chem. 2019, 21 (3), 550559,  DOI: 10.1039/C8GC03497D
  23. 23
    Baker, D. A.; Gallego, N. C.; Baker, F. S. On the Characterization and Spinning of an Organic-Purified Lignin toward the Manufacture of Low-Cost Carbon Fiber. J. Appl. Polym. Sci. 2012, 124 (1), 227234,  DOI: 10.1002/app.33596
  24. 24
    Qu, W.; Liu, J.; Xue, Y.; Wang, X.; Bai, X. Potential of Producing Carbon Fiber from Biorefinery Corn Stover Lignin with High Ash Content. J. Appl. Polym. Sci. 2018, 135 (4), 45736,  DOI: 10.1002/app.45736

    1–11.

  25. 25
    Sudo, K.; Shimizu, K. A New Carbon Fiber from Lignin. J. Appl. Polym. Sci. 1992, 44 (1), 127134,  DOI: 10.1002/app.1992.070440113
  26. 26
    Uraki, Y.; Kubo, S.; Kurakami, H.; Sano, Y. Activated Carbon Fibers from Acetic Acid Lignin. Holzforschung 1997, 51 (2), 188192,  DOI: 10.1515/hfsg.1997.51.2.188
  27. 27
    Kadla, J.; Kubo, S.; Venditti, R.; Gilbert, R.; Compere, A.; Griffith, W. Lignin-Based Carbon Fibers for Composite Fiber Applications. Carbon 2002, 40 (15), 29132920,  DOI: 10.1016/S0008-6223(02)00248-8
  28. 28
    Pandolfo, T.; Ruiz, V.; Seepalakottai, S.; Nerkar, J. Ch 2. General Properties of Electrochemical Capacitors. In  Supercapacitors: Materials, Systems, and Applications; Lu, M., Ed.; Wiley-VCH Verlag GmbH & Co.: Weinheim, Germany, 2013; pp 69110.
  29. 29
    Wei, J.; Geng, S.; Pitkänen, O.; Jarvinen, T.; Kordas, K.; Oksman, K. Green Carbon Nanofiber Networks for Advanced Energy Storage. ACS Applied Energy Materials 2020, 3 (4), 35303540,  DOI: 10.1021/acsaem.0c00065
  30. 30
    Lai, C.; Zhou, Z.; Zhang, L.; Wang, X.; Zhou, Q.; Zhao, Y.; Wang, Y.; Wu, X.-F.; Zhu, Z.; Fong, H. Free-Standing and Mechanically Flexible Mats Consisting of Electrospun Carbon Nanofibers Made from a Natural Product of Alkali Lignin as Binder-Free Electrodes for High-Performance Supercapacitors. J. Power Sources 2014, 247, 134141,  DOI: 10.1016/j.jpowsour.2013.08.082
  31. 31
    Hu, S.; Zhang, S.; Pan, N.; Hsieh, Y.-L. High Energy Density Supercapacitors from Lignin Derived Submicron Activated Carbon Fibers in Aqueous Electrolytes. J. Power Sources 2014, 270, 106112,  DOI: 10.1016/j.jpowsour.2014.07.063
  32. 32
    You, X.; Koda, K.; Yamada, T.; Uraki, Y. Preparation of Electrode for Electric Double Layer Capacitor from Electrospun Lignin Fibers. Holzforschung 2015, 69 (9), 10971106,  DOI: 10.1515/hf-2014-0262
  33. 33
    Ma, X.; Kolla, P.; Zhao, Y.; Smirnova, A. L.; Fong, H. Electrospun Lignin-Derived Carbon Nanofiber Mats Surface-Decorated with MnO2 Nanowhiskers as Binder-Free Supercapacitor Electrodes with High Performance. J. Power Sources 2016, 325, 541548,  DOI: 10.1016/j.jpowsour.2016.06.073
  34. 34
    Hu, S.; Hsieh, Y.-L. Lignin Derived Activated Carbon Particulates as an Electric Supercapacitor: Carbonization and Activation on Porous Structures and Microstructures. RSC Adv. 2017, 7 (48), 3045930468,  DOI: 10.1039/C7RA00103G
  35. 35
    Fang, W.; Yang, S.; Yuan, T.-Q.; Charlton, A.; Sun, R.-C. Effects of Various Surfactants on Alkali Lignin Electrospinning Ability and Spun Fibers. Ind. Eng. Chem. Res. 2017, 56 (34), 95519559,  DOI: 10.1021/acs.iecr.7b02494
  36. 36
    Shu, R.; Zhang, Q.; Ma, L.; Xu, Y.; Chen, P.; Wang, C.; Wang, T. Insight into the Solvent, Temperature and Time Effects on the Hydrogenolysis of Hydrolyzed Lignin. Bioresour. Technol. 2016, 221, 568575,  DOI: 10.1016/j.biortech.2016.09.043
  37. 37
    Cho, J.; Chu, S.; Dauenhauer, P. J.; Huber, G. W. Kinetics and Reaction Chemistry for Slow Pyrolysis of Enzymatic Hydrolysis Lignin and Organosolv Extracted Lignin Derived from Maplewood. Green Chem. 2012, 14 (2), 428439,  DOI: 10.1039/C1GC16222E
  38. 38
    Ma, R.; Xu, Y.; Zhang, X. Catalytic Oxidation of Biorefinery Lignin to Value-Added Chemicals to Support Sustainable Biofuel Production. ChemSusChem 2015, 8 (1), 2451,  DOI: 10.1002/cssc.201402503
  39. 39
    Ralph, J.; Landucci, L. L. NMR of Lignins. In Lignin and lignans: Advances in chemistry; Heitner, C., Dimmel, D., Schmidt, J., Eds.; CRC Press (Taylor & Francis Group): Boca Raton, FL, 2010; pp 137234.
  40. 40
    Li, S.; Lundquist, K. A New Method for the Analysis of Phenolic Groups in Lignins by 1H NMR Spectroscopy. Nord. Pulp Pap. Res. J. 1994, 9 (3), 191195,  DOI: 10.3183/npprj-1994-09-03-p191-195
  41. 41
    Gil, A.; Lopes, M.; Neto, C. P.; Rocha, J. Very High-Resolution 1H MAS NMR of a Natural Polymeric Material. Solid State Nucl. Magn. Reson. 1999, 15 (1), 5967,  DOI: 10.1016/S0926-2040(99)00047-8
  42. 42
    Lundquist, K.; Aasen, A. J.; Daasvatn, K.; Forsgren, B.; Gustafsson, J.-A.; Hogberg, B.; Becher, J. NMR Studies of Lignins. 4. Investigation of Spruce Lignin by 1H NMR Spectroscopy. Acta Chem. Scand. 1980, 34b, 2126,  DOI: 10.3891/acta.chem.scand.34b-0021
  43. 43
    Chen, C.-L.; Robert, D. Characterization of Lignin by 1H and 13C NMR Spectroscopy. Methods Enzymol. 1988, 161, 137174,  DOI: 10.1016/0076-6879(88)61017-2
  44. 44
    Capanema, E. A.; Balakshin, M. Y.; Kadla, J. F. A Comprehensive Approach for Quantitative Lignin Characterization by NMR Spectroscopy. J. Agric. Food Chem. 2004, 52 (7), 18501860,  DOI: 10.1021/jf035282b
  45. 45
    Chen, C.-L. Characterization of Milled Wood Lignins and Dehydrogenative Polymerisates from Monolignols by Carbon-13 NMR Spectroscopy. ACS Symp. Ser. 1998, 697, 255275,  DOI: 10.1021/bk-1998-0697.ch018
  46. 46
    Hatcher, P. G. Chemical Structural Studies of Natural Lignin by Dipolar Dephasing Solid-State 13C Nuclear Magnetic Resonance. Org. Geochem. 1987, 11 (1), 3139,  DOI: 10.1016/0146-6380(87)90049-0
  47. 47
    Sameni, J.; Krigstin, S.; Sain, M. Characterization of Lignins Isolated from Industrial Residues and Their Beneficial Uses. BioResources 2016, 11 (4), 84358456,  DOI: 10.15376/biores.11.4.8435-8456
  48. 48
    Ferrari, A. C.; Robertson, J. Raman Spectroscopy of Amorphous, Nanostructured, Diamond–like Carbon, and Nanodiamond. Philos. Trans. R. Soc., A 2004, 362 (1824), 24772512,  DOI: 10.1098/rsta.2004.1452
  49. 49
    Ferrari, A. C.; Robertson, J. Interpretation of Raman Spectra of Disordered and Amorphous Carbon. Phys. Rev. B: Condens. Matter Mater. Phys. 2000, 61 (20), 1409514107,  DOI: 10.1103/PhysRevB.61.14095
  50. 50
    Wei, J.; Geng, S.; Kumar, M.; Pitkänen, O.; Hietala, M.; Oksman, K. Investigation of Structure and Chemical Composition of Carbon Nanofibers Developed from Renewable Precursor. Front. Mater. 2019, 6, 334,  DOI: 10.3389/fmats.2019.00334
  51. 51
    Noori, A.; El-Kady, M. F.; Rahmanifar, M. S.; Kaner, R. B.; Mousavi, M. F. Towards Establishing Standard Performance Metrics for Batteries, Supercapacitors and Beyond. Chem. Soc. Rev. 2019, 48 (5), 12721341,  DOI: 10.1039/C8CS00581H
  52. 52
    Yu, D.; Goh, K.; Wang, H.; Wei, L.; Jiang, W.; Zhang, Q.; Dai, L.; Chen, Y. Scalable Synthesis of Hierarchically Structured Carbon Nanotube–Graphene Fibres for Capacitive Energy Storage. Nat. Nanotechnol. 2014, 9 (7), 555562,  DOI: 10.1038/nnano.2014.93
  53. 53
    Zhu, M.; Liu, H.; Cao, Q.; Zheng, H.; Xu, D.; Guo, H.; Wang, S.; Li, Y.; Zhou, J. Electrospun Lignin-Based Carbon Nanofibers as Supercapacitor Electrodes. ACS Sustainable Chem. Eng. 2020, 8 (34), 1283112841,  DOI: 10.1021/acssuschemeng.0c03062
  54. 54
    Schlee, P.; Hosseinaei, O.; Baker, D.; Landmér, A.; Tomani, P.; Mostazo-López, M. J.; Cazorla-Amorós, D.; Herou, S.; Titirici, M.-M. From Waste to Wealth: From Kraft Lignin to Free-Standing Supercapacitors. Carbon 2019, 145, 470480,  DOI: 10.1016/j.carbon.2019.01.035
  55. 55
    Ma, C.; Wu, L.; Dirican, M.; Cheng, H.; Li, J.; Song, Y.; Shi, J.; Zhang, X. ZnO-Assisted Synthesis of Lignin-Based Ultra-Fine Microporous Carbon Nanofibers for Supercapacitors. J. Colloid Interface Sci. 2021, 586, 412422,  DOI: 10.1016/j.jcis.2020.10.105
  56. 56
    Xuan, D.; Liu, J.; Wang, D.; Lu, Z.; Liu, Q.; Liu, Y.; Li, S.; Zheng, Z. Facile Preparation of Low-Cost and Cross-Linked Carbon Nanofibers Derived from PAN/PMMA/Lignin as Supercapacitor Electrodes. Energy Fuels 2021, 35 (1), 796805,  DOI: 10.1021/acs.energyfuels.0c02511
  57. 57
    Kim, M.; Kim, Y.; Lee, K. M.; Jeong, S. Y.; Lee, E.; Baeck, S. H.; Shim, S. E. Electrochemical Improvement Due to Alignment of Carbon Nanofibers Fabricated by Electrospinning as an Electrode for Supercapacitor. Carbon 2016, 99, 607618,  DOI: 10.1016/j.carbon.2015.12.068
  58. 58
    Jia, K.; Zhuang, X.; Cheng, B.; Shi, S.; Shi, Z.; Zhang, B. Solution Blown Aligned Carbon Nanofiber Yarn as Supercapacitor Electrode. J. Mater. Sci.: Mater. Electron. 2013, 24 (12), 47694773,  DOI: 10.1007/s10854-013-1472-z
  59. 59
    Zhang, Z.; Bai, B.; Zeng, L.; Wei, L.; Zhao, T. Aligned Electrospun Carbon Nanofibers as Electrodes for Vanadium Redox Flow Batteries. Energy Technol. 2019, 7 (10), 1900488,  DOI: 10.1002/ente.201900488
  60. 60
    Zhang, Y.; Song, X.; Xu, Y.; Shen, H.; Kong, X.; Xu, H. Utilization of Wheat Bran for Producing Activated Carbon with High Specific Surface Area via NaOH Activation Using Industrial Furnace. J. Cleaner Prod. 2019, 210, 366375,  DOI: 10.1016/j.jclepro.2018.11.041
  61. 61
    Carrott, P.; Carrott, M. R.; Suhas Comparison of the Dubinin–Radushkevich and Quenched Solid Density Functional Theory Approaches for the Characterisation of Narrow Microporosity in Activated Carbons Obtained by Chemical Activation with KOH or NaOH of Kraft and Hydrolytic Lignins. Carbon 2010, 48 (14), 41624169,  DOI: 10.1016/j.carbon.2010.07.031
  62. 62
    Ago, M.; Jakes, J. E.; Johansson, L.-S.; Park, S.; Rojas, O. J. Interfacial Properties of Lignin-Based Electrospun Nanofibers and Films Reinforced with Cellulose Nanocrystals. ACS Appl. Mater. Interfaces 2012, 4 (12), 68496856,  DOI: 10.1021/am302008p
  63. 63
    Bennett, A. E.; Rienstra, C. M.; Auger, M.; Lakshmi, K.; Griffin, R. G. Heteronuclear Decoupling in Rotating Solids. J. Chem. Phys. 1995, 103 (16), 69516958,  DOI: 10.1063/1.470372
  64. 64
    Earl, W. L.; VanderHart, D. Measurement of 13C Chemical Shifts in Solids. J. Magn. Reson. 1982, 48 (1), 3554,  DOI: 10.1016/0022-2364(82)90236-0
  65. 65
    Morcombe, C. R.; Zilm, K. W. Chemical Shift Referencing in MAS Solid State NMR. J. Magn. Reson. 2003, 162 (2), 479486,  DOI: 10.1016/S1090-7807(03)00082-X
  66. 66
    Schneider, C. A.; Rasband, W. S.; Eliceiri, K. W. NIH Image to ImageJ: 25 Years of Image Analysis. Nat. Methods 2012, 9 (7), 671675,  DOI: 10.1038/nmeth.2089
  67. 67
    Püspöki, Z.; Storath, M.; Sage, D.; Unser, M. Transforms and Operators for Directional Bioimage Analysis: A Survey. In Focus on Bio-Image Informatics; De Vos, W. H., Munck, S., Timmermans, J.-P., Eds.; Advances in Anatomy, Embryology and Cell Biology; Springer International Publishing: New York, 2016; Vol. 219, pp 6993.
  68. 68
    Lundahl, M. J.; Cunha, A. G.; Rojo, E.; Papageorgiou, A. C.; Rautkari, L.; Arboleda, J. C.; Rojas, O. J. Strength and Water Interactions of Cellulose I Filaments Wet-Spun from Cellulose Nanofibril Hydrogels. Sci. Rep. 2016, 6 (1), 113,  DOI: 10.1038/srep30695

Cited By

Click to copy section linkSection link copied!
Citation Statements
Explore this article's citation statements on scite.ai

This article is cited by 3 publications.

  1. Yong Ye, Hongchuan Zhang, Yu Shi, Yijang Liu, Huaming Li, Zhiyu Wang, Mei Yang, Bei Liu. A N/S co-doped free-standing carbon electrode derived from waste facial masks for anti-freezing flexible quasi-solid-state supercapacitors. Chemical Communications 2023, 59 (45) , 6925-6928. https://doi.org/10.1039/D3CC00932G
  2. Bony Thomas, Mohini Sain, Kristiina Oksman. Sustainable Carbon Derived from Sulfur-Free Lignins for Functional Electrical and Electrochemical Devices. Nanomaterials 2022, 12 (20) , 3630. https://doi.org/10.3390/nano12203630
  3. Lili Zhu, Shilian Lai, Jingyan Zhu, Qing Xu, Xinhua Li. A facile and environmentally friendly method for preparing supercapacitor electrode carbon-based materials with ultra-long cycling stability. Materials Today Communications 2022, 31 , 103717. https://doi.org/10.1016/j.mtcomm.2022.103717

ACS Sustainable Chemistry & Engineering

Cite this: ACS Sustainable Chem. Eng. 2021, 9, 36, 12142–12154
Click to copy citationCitation copied!
https://doi.org/10.1021/acssuschemeng.1c03549
Published September 1, 2021

Copyright © 2021 The Authors. Published by American Chemical Society. This publication is licensed under

CC-BY 4.0 .

Article Views

1172

Altmetric

-

Citations

Learn about these metrics

Article Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.

Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.

The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated.

  • Abstract

    Figure 1

    Figure 1. (a) 400.27 MHz 1H NMR spectra of LB, KR, HY, and SD dissolved in DMSO-d6. The 1H NMR resonance line at 2.50 ppm present in all the spectra corresponds to the solvent DMSO-d5(H). Assignment of protons in (i) CH2, CH3; (ii) CH2, CH; (iii) CH, CH3O, CH2O, CHO; (iv) aromatic H; (v) aromatic OH; and (vi) COOH. (b) 100.64 MHz 13C CP-MAS NMR spectra of LB, KR, HY, and SD. The MAS frequency was 8 kHz.

    Figure 2

    Figure 2. Thermogravimetric analysis of LB, KR, HY, and SD in N2 atmosphere.

    Figure 3

    Figure 3. Optical microscopy image of the (a) LB, (b) KR, (c) HY, and (d) SD solutions used for preparing the electrospinning precursor.

    Figure 4

    Figure 4. SEM images and the fiber diameter distributions of (a) C-LB200, (b) C-KR200, (c) C-HY200, and (d) C-SD200.

    Figure 5

    Figure 5. Orientation-related colored SEM images of (a) C-LB200, (b) C-KR200, (c) C-HY200, and (d) C-SD200. Zero degree corresponds to the vertical direction.

    Figure 6

    Figure 6. Raman spectra of C-LB200, C-KR200, C-HY200, and C-SD200.

    Figure 7

    Figure 7. Electrochemical properties of the randomly oriented CFNs. (a) Cyclic voltammograms (CV) of C-LB200, C-KR200, C-HY200, and C-SD200 under a scan rate of 100 mV s–1. (b) Galvanostatic charge–discharge (GCD) profiles of C-LB200, C-KR200, C-HY200, and C-SD200 using a current density of 10 A g–1. (c) Summary of the specific capacitance of C-LB200, C-KR200, C-HY200, and C-SD200 from the GCD under a series of current density. (d) Capacitance retention of C-LB200, C-KR200, C-HY200, and C-SD200 during 10 000 charge–discharge cycles under a current density of 10 A g–1.

    Figure 8

    Figure 8. Fiber morphology of the as-spun and the carbonized fiber networks. (a) SEM image of LB200, (b) SEM image of LB1500, (c) fiber diameter distribution of LB200 and LB1500, (d) SEM image of C-LB200, (e) SEM image of C-LB1500, and (f) fiber diameter distribution of C-LB200 and C-LB1500.

    Figure 9

    Figure 9. Orientation-related colored SEM images of (a) LB200, (b) LB-1500, (d) C-LB200, and (e) C-LB1500. Orientation distribution graphs of (c) LB200 and LB1500 and (f) C-LB200 and C-LB1500. Zero degree is aligned to the vertical direction.

    Figure 10

    Figure 10. Comparison of the electrochemical properties between the randomly oriented and highly oriented CFNs. (a) CV of C-LB1500. (b) GCD of C-LB1500. (c) CV of C-LB200 and C-LB1500 under a scan rate of 100 mV s–1. (d) GCD curves of C-LB200 and C-LB1500 using a current density of 10 A g–1. (e) Summary of the specific capacitance of C-LB200 and C-LB1500 from the GCD under a series of current densities. (f) Capacitance retention of C-LB200 and C-LB1500 during charge–discharge cycles under a current density of 10 A g–1.

    Figure 11

    Figure 11. Nyquist diagrams for C-LB200 and C-LB1500 obtained using electrochemical impedance spectroscopy (EIS). The testing potential is 300 mV.

  • References


    This article references 68 other publications.

    1. 1
      Bajpai, P. Lignin. In Carbon Fibre from Lignin; Springer Nature: Singapore, 2017; pp 1115.
    2. 2
      Henriksson, G. Lignin. In Wood chemistry and biotechnology; Ek, M., Gellerstedt, G., Henriksson, G., Eds.; Pulp and Paper Chemistry and Technology; Walter de Gruyter GmbH & Co.: Berlin, Germany, 2009; Vol. 1, pp 121145.
    3. 3
      Yuan, T.-Q.; Sun, S.-N.; Xu, F.; Sun, R.-C. Characterization of Lignin Structures and Lignin–Carbohydrate Complex (LCC) Linkages by Quantitative 13C and 2D HSQC NMR Spectroscopy. J. Agric. Food Chem. 2011, 59 (19), 1060410614,  DOI: 10.1021/jf2031549
    4. 4
      Gierer, J. Chemical Aspects of Kraft Pulping. Wood Sci. Technol. 1980, 14 (4), 241266,  DOI: 10.1007/BF00383453
    5. 5
      Gosselink, R. J. A. Lignin as a Renewable Aromatic Resource for the Chemical Industry . Ph.D. Thesis, Wageningen University, Wageningen, Netherlands, 2011.
    6. 6
      Chakar, F. S.; Ragauskas, A. J. Review of Current and Future Softwood Kraft Lignin Process Chemistry. Ind. Crops Prod. 2004, 20 (2), 131141,  DOI: 10.1016/j.indcrop.2004.04.016
    7. 7
      Henriksson, G.; Li, J.; Zhang, L.; Lindström, M. Lignin Utilization. In Thermochemical Conversion of Biomass to Liquid Fuels and Chemicals; Crocker, M., Ed.; RSC Energy and Environment Series; Royal Society of Chemistry: London, 2010.
    8. 8
      Lora, J. H. Lignin: A Platform for Renewable Aromatic Polymeric Materials. Quality Living Through Chemurgy and Green Chemistry; Springer: Berlin, Heidleberg, Germany, 2016; pp 221261.
    9. 9
      Biermann, C. J. Handbook of Pulping and Papermaking; Academic Press: Cambridge, MA, 1996.
    10. 10
      Chapple, C.; Ladisch, M.; Meilan, R. Loosening Lignin’s Grip on Biofuel Production. Nat. Biotechnol. 2007, 25 (7), 746748,  DOI: 10.1038/nbt0707-746
    11. 11
      Raud, M.; Tutt, M.; Olt, J.; Kikas, T. Dependence of the Hydrolysis Efficiency on the Lignin Content in Lignocellulosic Material. Int. J. Hydrogen Energy 2016, 41 (37), 1633816343,  DOI: 10.1016/j.ijhydene.2016.03.190
    12. 12
      Ragauskas, A. J.; Beckham, G. T.; Biddy, M. J.; Chandra, R.; Chen, F.; Davis, M. F.; Davison, B. H.; Dixon, R. A.; Gilna, P.; Keller, M. Lignin Valorization: Improving Lignin Processing in the Biorefinery. Science 2014, 344, 6185,  DOI: 10.1126/science.1246843
    13. 13
      Fache, M.; Boutevin, B.; Caillol, S. Vanillin Production from Lignin and Its Use as a Renewable Chemical. ACS Sustainable Chem. Eng. 2016, 4 (1), 3546,  DOI: 10.1021/acssuschemeng.5b01344
    14. 14
      Culebras, M.; Sanchis, M. J.; Beaucamp, A.; Carsí, M.; Kandola, B. K.; Horrocks, A. R.; Panzetti, G.; Birkinshaw, C.; Collins, M. N. Understanding the Thermal and Dielectric Response of Organosolv and Modified Kraft Lignin as a Carbon Fibre Precursor. Green Chem. 2018, 20 (19), 44614472,  DOI: 10.1039/C8GC01577E
    15. 15
      Jiang, W.; Liu, S.; Wu, C.; Liu, Y.; Yang, G.; Ni, Y. Super-Stable, Solvent-Resistant and Uniform Lignin Nanorods and Nanospheres with a High Yield in a Mild and Facile Process. Green Chem. 2020, 22 (24), 87348744,  DOI: 10.1039/D0GC02887H
    16. 16
      Yang, Y.; Deng, Y.; Tong, Z.; Wang, C. Renewable Lignin-Based Xerogels with Self-Cleaning Properties and Superhydrophobicity. ACS Sustainable Chem. Eng. 2014, 2 (7), 17291733,  DOI: 10.1021/sc500250b
    17. 17
      Kai, D.; Zhang, K.; Jiang, L.; Wong, H. Z.; Li, Z.; Zhang, Z.; Loh, X. J. Sustainable and Antioxidant Lignin–Polyester Copolymers and Nanofibers for Potential Healthcare Applications. ACS Sustainable Chem. Eng. 2017, 5 (7), 60166025,  DOI: 10.1021/acssuschemeng.7b00850
    18. 18
      Wei, C.; Zhu, X.; Peng, H.; Chen, J.; Zhang, F.; Zhao, Q. Facile Preparation of Lignin-Based Underwater Adhesives with Improved Performances. ACS Sustainable Chem. Eng. 2019, 7 (4), 45084514,  DOI: 10.1021/acssuschemeng.8b06731
    19. 19
      Baker, D. A.; Rials, T. G. Recent Advances in Low-Cost Carbon Fiber Manufacture from Lignin. J. Appl. Polym. Sci. 2013, 130 (2), 713728,  DOI: 10.1002/app.39273
    20. 20
      Geng, S.; Wei, J.; Jonasson, S.; Hedlund, J.; Oksman, K. Multifunctional Carbon Aerogels with Hierarchical Anisotropic Structure Derived from Lignin and Cellulose Nanofibers for CO2 Capture and Energy Storage. ACS Appl. Mater. Interfaces 2020, 12 (6), 74327441,  DOI: 10.1021/acsami.9b19955
    21. 21
      Guo, N.; Li, M.; Sun, X.; Wang, F.; Yang, R. Enzymatic Hydrolysis Lignin Derived Hierarchical Porous Carbon for Supercapacitors in Ionic Liquids with High Power and Energy Densities. Green Chem. 2017, 19 (11), 25952602,  DOI: 10.1039/C7GC00506G
    22. 22
      Herou, S.; Ribadeneyra, M. C.; Madhu, R.; Araullo-Peters, V.; Jensen, A.; Schlee, P.; Titirici, M. Ordered Mesoporous Carbons from Lignin: A New Class of Biobased Electrodes for Supercapacitors. Green Chem. 2019, 21 (3), 550559,  DOI: 10.1039/C8GC03497D
    23. 23
      Baker, D. A.; Gallego, N. C.; Baker, F. S. On the Characterization and Spinning of an Organic-Purified Lignin toward the Manufacture of Low-Cost Carbon Fiber. J. Appl. Polym. Sci. 2012, 124 (1), 227234,  DOI: 10.1002/app.33596
    24. 24
      Qu, W.; Liu, J.; Xue, Y.; Wang, X.; Bai, X. Potential of Producing Carbon Fiber from Biorefinery Corn Stover Lignin with High Ash Content. J. Appl. Polym. Sci. 2018, 135 (4), 45736,  DOI: 10.1002/app.45736

      1–11.

    25. 25
      Sudo, K.; Shimizu, K. A New Carbon Fiber from Lignin. J. Appl. Polym. Sci. 1992, 44 (1), 127134,  DOI: 10.1002/app.1992.070440113
    26. 26
      Uraki, Y.; Kubo, S.; Kurakami, H.; Sano, Y. Activated Carbon Fibers from Acetic Acid Lignin. Holzforschung 1997, 51 (2), 188192,  DOI: 10.1515/hfsg.1997.51.2.188
    27. 27
      Kadla, J.; Kubo, S.; Venditti, R.; Gilbert, R.; Compere, A.; Griffith, W. Lignin-Based Carbon Fibers for Composite Fiber Applications. Carbon 2002, 40 (15), 29132920,  DOI: 10.1016/S0008-6223(02)00248-8
    28. 28
      Pandolfo, T.; Ruiz, V.; Seepalakottai, S.; Nerkar, J. Ch 2. General Properties of Electrochemical Capacitors. In  Supercapacitors: Materials, Systems, and Applications; Lu, M., Ed.; Wiley-VCH Verlag GmbH & Co.: Weinheim, Germany, 2013; pp 69110.
    29. 29
      Wei, J.; Geng, S.; Pitkänen, O.; Jarvinen, T.; Kordas, K.; Oksman, K. Green Carbon Nanofiber Networks for Advanced Energy Storage. ACS Applied Energy Materials 2020, 3 (4), 35303540,  DOI: 10.1021/acsaem.0c00065
    30. 30
      Lai, C.; Zhou, Z.; Zhang, L.; Wang, X.; Zhou, Q.; Zhao, Y.; Wang, Y.; Wu, X.-F.; Zhu, Z.; Fong, H. Free-Standing and Mechanically Flexible Mats Consisting of Electrospun Carbon Nanofibers Made from a Natural Product of Alkali Lignin as Binder-Free Electrodes for High-Performance Supercapacitors. J. Power Sources 2014, 247, 134141,  DOI: 10.1016/j.jpowsour.2013.08.082
    31. 31
      Hu, S.; Zhang, S.; Pan, N.; Hsieh, Y.-L. High Energy Density Supercapacitors from Lignin Derived Submicron Activated Carbon Fibers in Aqueous Electrolytes. J. Power Sources 2014, 270, 106112,  DOI: 10.1016/j.jpowsour.2014.07.063
    32. 32
      You, X.; Koda, K.; Yamada, T.; Uraki, Y. Preparation of Electrode for Electric Double Layer Capacitor from Electrospun Lignin Fibers. Holzforschung 2015, 69 (9), 10971106,  DOI: 10.1515/hf-2014-0262
    33. 33
      Ma, X.; Kolla, P.; Zhao, Y.; Smirnova, A. L.; Fong, H. Electrospun Lignin-Derived Carbon Nanofiber Mats Surface-Decorated with MnO2 Nanowhiskers as Binder-Free Supercapacitor Electrodes with High Performance. J. Power Sources 2016, 325, 541548,  DOI: 10.1016/j.jpowsour.2016.06.073
    34. 34
      Hu, S.; Hsieh, Y.-L. Lignin Derived Activated Carbon Particulates as an Electric Supercapacitor: Carbonization and Activation on Porous Structures and Microstructures. RSC Adv. 2017, 7 (48), 3045930468,  DOI: 10.1039/C7RA00103G
    35. 35
      Fang, W.; Yang, S.; Yuan, T.-Q.; Charlton, A.; Sun, R.-C. Effects of Various Surfactants on Alkali Lignin Electrospinning Ability and Spun Fibers. Ind. Eng. Chem. Res. 2017, 56 (34), 95519559,  DOI: 10.1021/acs.iecr.7b02494
    36. 36
      Shu, R.; Zhang, Q.; Ma, L.; Xu, Y.; Chen, P.; Wang, C.; Wang, T. Insight into the Solvent, Temperature and Time Effects on the Hydrogenolysis of Hydrolyzed Lignin. Bioresour. Technol. 2016, 221, 568575,  DOI: 10.1016/j.biortech.2016.09.043
    37. 37
      Cho, J.; Chu, S.; Dauenhauer, P. J.; Huber, G. W. Kinetics and Reaction Chemistry for Slow Pyrolysis of Enzymatic Hydrolysis Lignin and Organosolv Extracted Lignin Derived from Maplewood. Green Chem. 2012, 14 (2), 428439,  DOI: 10.1039/C1GC16222E
    38. 38
      Ma, R.; Xu, Y.; Zhang, X. Catalytic Oxidation of Biorefinery Lignin to Value-Added Chemicals to Support Sustainable Biofuel Production. ChemSusChem 2015, 8 (1), 2451,  DOI: 10.1002/cssc.201402503
    39. 39
      Ralph, J.; Landucci, L. L. NMR of Lignins. In Lignin and lignans: Advances in chemistry; Heitner, C., Dimmel, D., Schmidt, J., Eds.; CRC Press (Taylor & Francis Group): Boca Raton, FL, 2010; pp 137234.
    40. 40
      Li, S.; Lundquist, K. A New Method for the Analysis of Phenolic Groups in Lignins by 1H NMR Spectroscopy. Nord. Pulp Pap. Res. J. 1994, 9 (3), 191195,  DOI: 10.3183/npprj-1994-09-03-p191-195
    41. 41
      Gil, A.; Lopes, M.; Neto, C. P.; Rocha, J. Very High-Resolution 1H MAS NMR of a Natural Polymeric Material. Solid State Nucl. Magn. Reson. 1999, 15 (1), 5967,  DOI: 10.1016/S0926-2040(99)00047-8
    42. 42
      Lundquist, K.; Aasen, A. J.; Daasvatn, K.; Forsgren, B.; Gustafsson, J.-A.; Hogberg, B.; Becher, J. NMR Studies of Lignins. 4. Investigation of Spruce Lignin by 1H NMR Spectroscopy. Acta Chem. Scand. 1980, 34b, 2126,  DOI: 10.3891/acta.chem.scand.34b-0021
    43. 43
      Chen, C.-L.; Robert, D. Characterization of Lignin by 1H and 13C NMR Spectroscopy. Methods Enzymol. 1988, 161, 137174,  DOI: 10.1016/0076-6879(88)61017-2
    44. 44
      Capanema, E. A.; Balakshin, M. Y.; Kadla, J. F. A Comprehensive Approach for Quantitative Lignin Characterization by NMR Spectroscopy. J. Agric. Food Chem. 2004, 52 (7), 18501860,  DOI: 10.1021/jf035282b
    45. 45
      Chen, C.-L. Characterization of Milled Wood Lignins and Dehydrogenative Polymerisates from Monolignols by Carbon-13 NMR Spectroscopy. ACS Symp. Ser. 1998, 697, 255275,  DOI: 10.1021/bk-1998-0697.ch018
    46. 46
      Hatcher, P. G. Chemical Structural Studies of Natural Lignin by Dipolar Dephasing Solid-State 13C Nuclear Magnetic Resonance. Org. Geochem. 1987, 11 (1), 3139,  DOI: 10.1016/0146-6380(87)90049-0
    47. 47
      Sameni, J.; Krigstin, S.; Sain, M. Characterization of Lignins Isolated from Industrial Residues and Their Beneficial Uses. BioResources 2016, 11 (4), 84358456,  DOI: 10.15376/biores.11.4.8435-8456
    48. 48
      Ferrari, A. C.; Robertson, J. Raman Spectroscopy of Amorphous, Nanostructured, Diamond–like Carbon, and Nanodiamond. Philos. Trans. R. Soc., A 2004, 362 (1824), 24772512,  DOI: 10.1098/rsta.2004.1452
    49. 49
      Ferrari, A. C.; Robertson, J. Interpretation of Raman Spectra of Disordered and Amorphous Carbon. Phys. Rev. B: Condens. Matter Mater. Phys. 2000, 61 (20), 1409514107,  DOI: 10.1103/PhysRevB.61.14095
    50. 50
      Wei, J.; Geng, S.; Kumar, M.; Pitkänen, O.; Hietala, M.; Oksman, K. Investigation of Structure and Chemical Composition of Carbon Nanofibers Developed from Renewable Precursor. Front. Mater. 2019, 6, 334,  DOI: 10.3389/fmats.2019.00334
    51. 51
      Noori, A.; El-Kady, M. F.; Rahmanifar, M. S.; Kaner, R. B.; Mousavi, M. F. Towards Establishing Standard Performance Metrics for Batteries, Supercapacitors and Beyond. Chem. Soc. Rev. 2019, 48 (5), 12721341,  DOI: 10.1039/C8CS00581H
    52. 52
      Yu, D.; Goh, K.; Wang, H.; Wei, L.; Jiang, W.; Zhang, Q.; Dai, L.; Chen, Y. Scalable Synthesis of Hierarchically Structured Carbon Nanotube–Graphene Fibres for Capacitive Energy Storage. Nat. Nanotechnol. 2014, 9 (7), 555562,  DOI: 10.1038/nnano.2014.93
    53. 53
      Zhu, M.; Liu, H.; Cao, Q.; Zheng, H.; Xu, D.; Guo, H.; Wang, S.; Li, Y.; Zhou, J. Electrospun Lignin-Based Carbon Nanofibers as Supercapacitor Electrodes. ACS Sustainable Chem. Eng. 2020, 8 (34), 1283112841,  DOI: 10.1021/acssuschemeng.0c03062
    54. 54
      Schlee, P.; Hosseinaei, O.; Baker, D.; Landmér, A.; Tomani, P.; Mostazo-López, M. J.; Cazorla-Amorós, D.; Herou, S.; Titirici, M.-M. From Waste to Wealth: From Kraft Lignin to Free-Standing Supercapacitors. Carbon 2019, 145, 470480,  DOI: 10.1016/j.carbon.2019.01.035
    55. 55
      Ma, C.; Wu, L.; Dirican, M.; Cheng, H.; Li, J.; Song, Y.; Shi, J.; Zhang, X. ZnO-Assisted Synthesis of Lignin-Based Ultra-Fine Microporous Carbon Nanofibers for Supercapacitors. J. Colloid Interface Sci. 2021, 586, 412422,  DOI: 10.1016/j.jcis.2020.10.105
    56. 56
      Xuan, D.; Liu, J.; Wang, D.; Lu, Z.; Liu, Q.; Liu, Y.; Li, S.; Zheng, Z. Facile Preparation of Low-Cost and Cross-Linked Carbon Nanofibers Derived from PAN/PMMA/Lignin as Supercapacitor Electrodes. Energy Fuels 2021, 35 (1), 796805,  DOI: 10.1021/acs.energyfuels.0c02511
    57. 57
      Kim, M.; Kim, Y.; Lee, K. M.; Jeong, S. Y.; Lee, E.; Baeck, S. H.; Shim, S. E. Electrochemical Improvement Due to Alignment of Carbon Nanofibers Fabricated by Electrospinning as an Electrode for Supercapacitor. Carbon 2016, 99, 607618,  DOI: 10.1016/j.carbon.2015.12.068
    58. 58
      Jia, K.; Zhuang, X.; Cheng, B.; Shi, S.; Shi, Z.; Zhang, B. Solution Blown Aligned Carbon Nanofiber Yarn as Supercapacitor Electrode. J. Mater. Sci.: Mater. Electron. 2013, 24 (12), 47694773,  DOI: 10.1007/s10854-013-1472-z
    59. 59
      Zhang, Z.; Bai, B.; Zeng, L.; Wei, L.; Zhao, T. Aligned Electrospun Carbon Nanofibers as Electrodes for Vanadium Redox Flow Batteries. Energy Technol. 2019, 7 (10), 1900488,  DOI: 10.1002/ente.201900488
    60. 60
      Zhang, Y.; Song, X.; Xu, Y.; Shen, H.; Kong, X.; Xu, H. Utilization of Wheat Bran for Producing Activated Carbon with High Specific Surface Area via NaOH Activation Using Industrial Furnace. J. Cleaner Prod. 2019, 210, 366375,  DOI: 10.1016/j.jclepro.2018.11.041
    61. 61
      Carrott, P.; Carrott, M. R.; Suhas Comparison of the Dubinin–Radushkevich and Quenched Solid Density Functional Theory Approaches for the Characterisation of Narrow Microporosity in Activated Carbons Obtained by Chemical Activation with KOH or NaOH of Kraft and Hydrolytic Lignins. Carbon 2010, 48 (14), 41624169,  DOI: 10.1016/j.carbon.2010.07.031
    62. 62
      Ago, M.; Jakes, J. E.; Johansson, L.-S.; Park, S.; Rojas, O. J. Interfacial Properties of Lignin-Based Electrospun Nanofibers and Films Reinforced with Cellulose Nanocrystals. ACS Appl. Mater. Interfaces 2012, 4 (12), 68496856,  DOI: 10.1021/am302008p
    63. 63
      Bennett, A. E.; Rienstra, C. M.; Auger, M.; Lakshmi, K.; Griffin, R. G. Heteronuclear Decoupling in Rotating Solids. J. Chem. Phys. 1995, 103 (16), 69516958,  DOI: 10.1063/1.470372
    64. 64
      Earl, W. L.; VanderHart, D. Measurement of 13C Chemical Shifts in Solids. J. Magn. Reson. 1982, 48 (1), 3554,  DOI: 10.1016/0022-2364(82)90236-0
    65. 65
      Morcombe, C. R.; Zilm, K. W. Chemical Shift Referencing in MAS Solid State NMR. J. Magn. Reson. 2003, 162 (2), 479486,  DOI: 10.1016/S1090-7807(03)00082-X
    66. 66
      Schneider, C. A.; Rasband, W. S.; Eliceiri, K. W. NIH Image to ImageJ: 25 Years of Image Analysis. Nat. Methods 2012, 9 (7), 671675,  DOI: 10.1038/nmeth.2089
    67. 67
      Püspöki, Z.; Storath, M.; Sage, D.; Unser, M. Transforms and Operators for Directional Bioimage Analysis: A Survey. In Focus on Bio-Image Informatics; De Vos, W. H., Munck, S., Timmermans, J.-P., Eds.; Advances in Anatomy, Embryology and Cell Biology; Springer International Publishing: New York, 2016; Vol. 219, pp 6993.
    68. 68
      Lundahl, M. J.; Cunha, A. G.; Rojo, E.; Papageorgiou, A. C.; Rautkari, L.; Arboleda, J. C.; Rojas, O. J. Strength and Water Interactions of Cellulose I Filaments Wet-Spun from Cellulose Nanofibril Hydrogels. Sci. Rep. 2016, 6 (1), 113,  DOI: 10.1038/srep30695
  • Supporting Information

    Supporting Information


    The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acssuschemeng.1c03549.

    • 13C NMR spectra of lignins; molecule size distribution of lignins; magnified OM image of SD solution; illustration of the electrospinning setup; SEM images of as-spun fiber networks; CV plots and GCD curves of CFNs; bending test of the electrode after the electrochemical testing; N2 adsorption isotherms of the CFNs at 77 K; pore size distribution of the CFNs based on nonlocal density functional theory (PDF)


    Terms & Conditions

    Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.