Influence of KHCO3 Activation on Characteristics of Biomass-Derived Carbons for Supercapacitor

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.

Novel hierarchical porous carbon materials derived from bamboo shoot shells for high-performance symmetric supercapacitor

“…Table 2 Comparison of BBC-800-0 with the recently reported biomass-derived porous carbon materials Furthermore, the activation effects of different carbon precursors vary greatly. The solid cellulose structure might not be easily etched onto the mesoporous structures compared with other morphological structures, while 3D network structures expand horizontally and vertically [17]. Therefore, the flexible lamellar structure of bamboo shoot shells is inclined to transition from a microporous structure to a mesoporous structure.…”

“…In these materials, biomass carbon materials have elicited attention for their sustainability and renewability and exhibited excellent electrochemical performance because of their natural porous structure and high electrical conductivity that collectively contribute to their superior electrochemical properties [12,13]. Examples of these materials include barley straw [14], lotus hemp [15], walnut shells [16], and pleurotus eryngii [17]. Among these materials, bamboo shoot shells, as a renewable biomass resource, possess a unique porous skeleton structure that contributes to the formation of porous carbon materials.…”