Wood-derived carbon electrodes prepared via simple surface treatment for high performance supercapacitors

Surface modification of porous wood carbon (PWC) has been studied to improve its electrochemical performance. However, current research has not fully understood the impact of surface chemical properties of modified PWC on electrochemical performance and the mechanism of capacitive energy storage. Herein, a simple hydrothermal method is used to obtain HNO3-treated porous wood carbon (HPWC) by surface modification of PWC using HNO3 solution. Etching PWC with HNO3 greatly increases the specific surface area and improves the pore size, which is conducive to ion/electron transport. At the same time, various oxygen-containing functional groups are introduced, improving the capacitance performance. Furthermore, the dynamic analysis of the electrode reveals that the higher rate performance of the electrode is related to the lower relaxation time constant and higher surface capacitance contribution rate. The results showed that the 6 M HNO3-treated porous wood carbon (HPWC−6) had a high area specific capacitance (747.1 mF cm−2 at 1 mA cm−2) and rate capability (38.1 % capacitance retention at 20 mF cm−2). The HPWC−6 assembled into a symmetrical supercapacitor can power an LED light, revealing its practical value. This study combines experimental and theoretical analysis to provide guidance for the preparation of high-performance wood-based supercapacitor electrodes.