Self-supporting porous carbon fiber cloth synthesized via potassium salt activation with enhanced capacitive performance

Porous carbon materials are regarded as ideal electrode materials for supercapacitors due to their advantages such as tunable pore structure and good electrical conductivity. Therefore, this study activated commercial cotton cloth (CC) with three potassium salts (K 2 CO 3 , CH 3 COOK, and KHCO 3 ) to investigate the effects of different salts on the microstructure and electrochemical performance of the obtained porous carbon fiber cloth. During carbonization, the potassium salts decompose and undergo redox reactions with carbon, generating gases such as CO 2 and CO as well as active potassium. These products collectively contribute to gasification erosion and chemical etching of the cotton cloth, thereby constructing a hierarchical pore structure containing micropores, mesopores, and macropores. The results indicate that the sample activated by KHCO 3 (denoted as KHCO 3 –0.3) exhibited optimal porosity characteristics, with a specific surface area reaching 911 m 2 g −1 and a micropore volume of 0.39 cm 3 g −1 , significantly enhancing its charge storage capability. The material demonstrated a specific capacitance of 313 F g −1 at the current density of 0.2 A g −1 , and even maintained 120 F g −1 at a high current density of 90 A g −1 . A symmetric supercapacitor assembled based on KHCO 3 –0.3 achieved a specific capacitance of 121 F g −1 at 0.2 A g −1 , with corresponding energy and power densities of 16 Wh kg −1 and 16 kW kg −1 , respectively. It also retained 57% of its capacitance at 30 A g −1 and demonstrated that after 25,000 cycles, the capacitor still maintained 98% cycle stability. This potassium salt activation strategy is both environmentally friendly and economical, thus offering a promising route for valorizing cotton textiles into high-value energy storage materials.