Potassium Humate-Derived Nitrogen-Doped Activated Carbons with Narrow Micropore Size Distribution for High-Performance Supercapacitors

Micro-porous activated carbons (ACs) with a narrow pore size distribution of 0.4-0.6nm and high specific surface areas (1160-1315m²g-1) are prepared from environment-friendly, low-grade potassium humate (HA-K, carbon resource) and mild activating agent potassium acetate (CH₃COOK). Microstructure characterizations indicate that the introduction of activating agent CH₃COOK is a key step to achieve high specific surface area and carbonization degree. These ACs contain small amount of oxygen and nitrogen, and show obvious pseudo-capacitance besides double layer capacitance. As a result, the optimized ACs achieve high specific capacitances of 311Fg-1 and 317Fg-1 at 0.1Ag-1 in 2M KOH and 1M H₂SO₄ aqueous electrolytes, respectively. This sample also shows a good charge-discharge cycling stability within 10 000 cycles.