Biomass-derived three-dimensional porous carbon membrane electrode for high-performance aqueous supercapacitors: An alternative of powdery carbon materials

Here, we report a nature-inspired three-dimensional (3D) porous carbon membrane (denoted as CDCM) derived from low-cost biomass (carrot) as a self-supported electrode for high performance aqueous supercapacitor (SC) device. Benefitting from the high surface area, the abundant porosity, the high electrical conductivity, and the good mechanical strength, the CDCM electrode exhibits excellent capacitive performance in aqueous electrolyte (6.0 M KOH). In the operating potential window of 0–1.0 V, the CDCM-based symmetric SC exhibits a large specific capacitance up to 161 F g⁻¹ at 0.2 A g⁻¹, an outstanding rate capability (81.8% retention at 20 A g⁻¹), a superior cycling stability (no capacitance decay) and 100% Coulombic efficiency over 20000 cycles, and high energy densities of 5.6–4.6 Wh kg⁻¹ at power densities of 49.8–5884.4 W kg⁻¹. Notably, the operating potential window of the CDCM-based SC can be further expanded to 0–1.4 V, at which a much enhanced capacitive performance is achieved (196 F g⁻¹ at 0.2 A g⁻¹, 73% retention at 20 A g⁻¹, 90% retention after 20000 cycles, and energy densities of 13.3–9.7 Wh kg⁻¹ at power densities of 70.0–8748.3 W kg⁻¹). This work provides a new insight into the development of structurally integrated self-supported carbon-based electrodes for high-performance supercapacitors.