KOH Chemical-Activated Porous Carbon Sponges for Monolithic Supercapacitor Electrodes

Developing monolithic electrodes with high capacitor performance remains a challenge in energy storage field. KOH is applied to chemically activated commercial melamine sponges, and it can prepare monolithic N-/O-doped carbon sponge (NOCS) electrodes. The graphitization degree, heteroatom content, and pore size distribution can be regulated by adjusting the KOH/melamine sponge mass ratio. The optimal electrode demonstrates specific capacitances of 440 F g(-1) at 1.0 mV s(-1) and 273 F g(-1) at 0.5 A g(-1), and the capacitance retention remains 85.0% after 10,000 charging-discharging cycles at 10 A g(-1). The charge storage mechanism in NOCSs is systematically studied by separating the capacitive effect (pseudo-capacitance) from the diffusion-controlled contribution (electrical double-layer capacitance). Moreover, the capacitance performances of NOCSs in a polyvinyl alcohol/KOH electrolyte are also investigated by assembling all-solid-state supercapacitors, which can output an energy density of 5.61 W h kg(-1) at 250 W kg(-1) and power three light-emitting diodes with different colors.

Automated summary

Developing monolithic electrodes with high capacitor performance using chemically activated commercial melamine sponges and KOH is a challenge in the energy storage field. The study demonstrates that adjusting the KOH/melamine sponge mass ratio can regulate the graphitization degree, heteroatom content, and pore size distribution of the monolithic N-/O-doped carbon sponge electrodes. The optimized electrode shows promising specific capacitances and retention rates, and the charge storage mechanism in NOCSs is systematically studied to separate different capacitance contributions. Additionally, the NOCSs show good capacitance performances in all-solid-state supercapacitors, providing high energy density and power output for driving LED devices.