Electrochemical Exfoliation of Carbon Paper for Binder-Free Cathodes in Zinc-Ion Supercapacitors
Zinc-ion supercapacitors (ZISCs) are promising energy storage devices due to their low cost, high safety, and minimal environmental impact. However, their low energy density and poor cycling performance hinder practical application. This study presents a simple electrochemical exfoliation method to reconstruct the surface of carbon paper, introducing oxygen functional groups that enhance pseudocapacitance. The resulting binder-free electrode (EECP) exhibits a large surface area and rapid charge transfer, leading to a dominant capacitive-type charge storage mechanism with 78.8% capacitive contribution at 10 mV/s. The EECP electrode delivers a maximum specific capacitance of 252.5 F/g at 1 A/g and retains 81.7% of its capacitance after 10,000 cycles. A full ZISC device, assembled with EECP as the cathode, Zn as the anode, and 1 mol L−1 ZnSO4 aqueous electrolyte, achieves a capacitance of 186.22 F/g at 1 A/g, a capacitance retention of 97.01% after 10,000 cycles, and an energy density of 46.6 Wh/kg at a power density of 500.4 W/kg. These results demonstrate that EECP is a promising cathode material for high-rate, next-generation zinc-ion supercapacitors.