Influence of KHCO3 Activation on Characteristics of Biomass-Derived Carbons for Supercapacitor
Yudan Yuan, Yi Sun, Chenguang Liu, Li Yang, Cezhou Zhao
Abstract
Biomass materials with representative morphologies and compositions were employed to study the activation effect of KHCO3. As the activation time increased from 1 to 3 h, the products derived from puffed rice and pleurotus eryngii achieved a hierarchical porous structure, while the products derived from cotton still presented a microporous structure. In the electrochemical test of a three-electrode system, the specific capacitance of these products was 352, 319, and 216 F g−1, respectively. In the two-electrode system, the PR-2-based symmetric supercapacitor presented with a specific capacitance of 280.7 F g−1 at 0.5 A g−1, and the energy density of 14.03 Wh kg−1 at 150.04 W kg−1 and an energy density retention of 73.7% was at an even higher power density of 8380.4 W kg−1. After 10,000 cycles of charging and discharging at 5 A g−1, the specific capacitance retention of the supercapacitor reached 108.8%. Based on the experimental analysis, a likely mechanism for the formation of pores was proposed. The results indicate that biomass materials with soft layered or a network structure are the best candidates to obtain a hierarchical porous structure by KHCO3 activation.