Stable Lignin-Rich Nanofibers for Binder-Free Carbon Electrodes in Supercapacitors

Abstract

In this work, 1,2,4,5-benzenetetracarboxylic acid (BT) is used as a cross-linker to improve the oxidative thermostabilization of lignin-rich nanofibers so that the activated carbon nanofiber (ACNF) sheets can be prepared from lignins. As sources, we used organosolv lignins from sugarcane bagasse (LB), para rubber wood chip (LR), and palm kernel shell (LP). The addition of BT imparts hydrogen bond interactions between BT and lignin and increases the oxidation degree of lignin during the stabilization, enabling retention of nanofiber morphology after heat treatments. The preparation of activated carbon in the form of nanofibers substantially enhances the specific surface area of the materials when compared with the activated carbon powders from pure lignins. The properties of the resulting ACNFs are influenced by the structure and composition of lignins. With the synergistic effects of a small fiber diameter (688 ± 80 nm), a high content of heteroatom (O atomic content ∼5.1%), a high graphitic carbon structure (I D /I G ratio ∼0.98), a high conductivity (N I>0.1nA /A ∼3479 ± 404 pixel μm −2 at 0.5 V), and a high specific surface area (∼2195 m 2 g −1 ), the ACNFs from LB show the highest specific capacitance of 182 F g −1 (at a current density of 0.1 A g −1 in 1.0 M H 2 SO 4 electrolyte) with good cycling stability (95.7% capacitance retention after 6000 cycles). A maximum energy density of 31 W h kg −1 at a power density of 240 W kg −1 can be achieved from the LB/PEO/BT ACNFs. Their performance is almost comparable to that of polyacrylonitrile ACNFs. These findings demonstrate a simple and effective approach to produce lignin-based ACNFs from diverse biomass feedstock for sustainable development of renewable materials for supercapacitor electrodes.

Carbon Nanomaterials‐Enabled High‐Performance Supercapacitors: A Review

“…The lamellar HPC/PANI composite electrode delivered the highest specific capacitance of 643 F g −1 at a current density of 1 A g −1 with excellent rate performance, where the permeable, hierarchically porous, and conductive network structure can facilitate the electron and ion transmission. Khamnantha et al [ 53 ] prepared AC nanofiber (ACNF) utilizing 1,2,4,5‐benzenetetracarboxylic acid (BT) as a crosslinker, lignin as a carbon source, in which the lignin came from sugarcane bagasse (LB), para rubber wood chip (LR), and palm kernel shell (LP), respectively. As shown in Figure , the highest specific capacitance of LB‐based ACNFs (LB/PEO/BT ACNFs) was 182 F g −1 at 0.1 A g −1 in H 2 SO 4 electrolytes with a satisfactory cycling stability of 95.7% after 6000 cycles.…”

“…i) Cycle stability of LB/PEO/BT ACNFs at a current density of 0.1 A g À1 .The inset shows the photograph of red, yellow, and green lightemitting diodes power supplied by a SC using LB/PEO/BT ACNFs as electrodes. Reproduced with permission [53]. Copyright 2021, American Chemical Society.…”

Ti–Cr–N Nanopyramid/Nitrogen-Doped Carbon Quantum Dot/Stainless Steel Mesh as a Flexible Supercapacitor Electrode

“…The electrochemical performance can be greatly enhanced by rationally designing electrode nanostructures and adopting an adequate electrolyte combination. − Among distinct electrode types, thin-film electrodes (TFEs) with low and homogeneous thickness can ensure quick electrochemical reactivity due to the availability of shorter electronic and ionic transport routes . Notably, the TFE construction includes portability and adaptability properties for the accomplished device, offering easy incorporation into flexible electronics.…”