Reconstruction of the surface of carbon paper by electrochemical exfoliation to produce a binder-free electrode for Zn-ion storage

Zinc-ion supercapacitors (ZISCs) have received considerable interest for energy storage because of their low cost, high safety, and minimal environmental impact. However, they have a low energy density and poor cycling performance. The design of a better cathode material is needed to overcome these limitations. A simple method was used to synthesize binder-free electrochemically exfoliated carbon paper (EECP) which modifies the surface of the paper by introducing oxygen functional groups and thus improves its pseudocapacitance. When used in a Zn-ion supercapacitor (ZISC), an EECP-based cathode provides a large surface area and quick charge transfer. As a result, the ZISC had remarkable charge storage properties and had a dominant capacitive-type charge storage mechanism with 78.8% retention of capacity at 10 mV/s of the total storage. Furthermore, at 1 A/g, the EECP electrode had a maximum capacitance of 252.5 F/g. The EECP electrode retained 81.7% of its capacitance after 10 000 cycles, indicating its promise for use in the growing renewable energy sector. A ZISC was also constructed using EECP as the positive electrode and Zn as the negative electrode with a 1 mol L−1 ZnSO4 electrolyte. It had a capacitance of 186.22 F/g at 1 A/g and a 97.01% retention rate after 10 000 cycles. It also had an excellent energy density of 46.6 Wh/kg at a power density of 500.4 W/kg. The material is therefore suitable for use in high-rate next-generation ZISCs.