H<sub>3</sub>PO<sub>4</sub>-Assisted Synthesis of Apricot Shell Lignin-Based Activated Carbon for Capacitors: Understanding the Pore Structure/Electrochemical Performance Relationship
Liangcai Wang, Jielong Wu, Huanhuan Ma, Guolin Han, Derui Yang, Yu Chen, Jianbin Zhou
Abstract
The main focus of this study was to give an idea for the value added from lignin and further understand the pore structure/electrochemical performance relationship. A case study of using H3PO4-assisted apricot shell lignin (ASL) was used to synthesize apricot shell lignin-based activated carbon (AAC) for capacitors. Considering performance and cost, the activation temperature of ASL was 550 °C. The as-obtained AAC-3 possesses the highest specific surface area (1474.82 m2/g) and the highest mass-specific capacitance (169.05 F/g) upon the current density of 0.5 A/g. Compared with the correlation coefficient (R2) of specific surface area and mass-specific capacitance, the R2 of V0.85–1.93 nm and mass-specific capacitance was higher. Therefore, when employing a three-electrode configuration with a 6 M KOH electrolyte, the V0.85–1.93 nm can be used as a universal predictor of mass-specific capacitance at a low current density ranging from 0.50 to 10.00 A/g. Additionally, such a range of characterized pore size (0.85–1.93 nm) exhibited 2.83–6.43 times the diameters of K+ and OH–.