Dual-salt synergistic activation of hierarchical porous carbons derived from cellulose-chitosan biomass for high-performance supercapacitors

Abstract

The combustion of fossil fuels has triggered a series of environmental, climatic, and resource-related issues, while the intermittency of renewable energy sources constrains the development of clean energy. In this study, a series of porous carbon materials (CSHPC-x-T) were successfully prepared using a mixed-salt (potassium citrate and sodium bicarbonate) activation approach, with hydroxypropyl cellulose and chitosan serving as mixed biomass carbon sources. By precisely adjusting the activator ratio, the pore structure of the materials was finely tuned. Among them, CSHPC-2-700 exhibited the best electrochemical performance. In a three-electrode system, CSHPC-2-700 demonstrated a high specific capacitance of 392.9 F g⁻¹, significantly surpassing those (K-CSHPC-2-700 and N-CSHPC-2-700) prepared via single-salt activation, and exhibited excellent rate capability (261.6 F g⁻¹ at 50 A g⁻¹ and 204.4 F g⁻¹ at 100 A g⁻¹). In a two-electrode configuration, the symmetric supercapacitor based on CSHPC-2-700 displayed an ultra-long cycle life in 6 M KOH electrolyte, retaining 90.77 % initial capacitance after 30,000 consecutive charge-discharge cycles at 10 A g⁻¹. These outstanding performances indicate the great potential of CSHPC-2-700 as a high-performance electrode material for supercapacitors.