Dual-activator strategy to facilely tune pore structure of lignin-based porous carbon for high performance supercapacitors

Abstract

Based on the energy storage principle of electric double-layer supercapacitors, regulating the hierarchical pore structure of porous carbon is of great significance but remains a formidable challenge. Herein, we propose a dual-activator strategy of K2CO3/K2FeO4 synergistic activation to tune the pore structure of carbon materials, successfully synthesizing lignin-based porous carbon (CFeK-0.5) with hierarchical pore characteristics. The KOH generated from K2FeO4 can function at a lower temperature compared to K2CO3. Subsequently, K2CO3 further reacts with the carbon skeleton within the pores created by KOH. The two agents coordinate at high temperature, optimizing the pore channel structure and providing more ample space for ion storage. Consequently, at a current density of 1 A/g, the specific capacitance of CFeK-0.5 prepared using the dual-activator strategy is significantly enhanced, reaching 165.8 F/g, while those of single K2FeO4 activation (CFe) and single K2CO3 activation (CK) are 104.1 F/g and 123.5 F/g, respectively. In the symmetric supercapacitor, CFeK-0.5 demonstrates favorable electrochemical performance. It retains 82.7% of its specific capacitance when the current density is increased from 1 A/g to 10 A/g, indicating excellent rate capability. After 10,000 charge-discharge cycles at a current density of 10 A/g, the capacitance remains at 98% of its initial value. These results indicate that the dual-activator strategy holds great potential to tune pore structure of lignin-based porous carbon for high performance supercapacitors.