Preparation of Porous Carbon Spheres Under Different Activation Conditions from 2-Keto-l-gulonic Acid Mother Liquor for Electric Double-Layer Capacitor

Abstract

2-Keto-l-gulonic acid mother liquor (GAML) as an organic waste solution contained highly polluting contents would pollute the environment if discharged directly. As reported in our previous paper, GAML was used as the precursor to prepare porous carbon sphere (PCS) as carbon-based electrode materials of electric double-layer capacitor (EDLC) to create its high value-added utilization, and in the carbonization process, Fe(NO3)3·9H2O acted as an oxidizing agent. Since the carbon sphere was a carbon material with a special morphology, the effect of activation conditions (activation ratio, activation temperature and activation time) on the pore structure and the electrochemical performance of PCS were explored in this paper. PCS was derived via hydrothermal carbonization, carbonization and KOH activation successively, and the as-prepared samples had excellent porosity and high SSA of 2747 m2 g−1. Besides, the specific capacitance of PCS-7-700-1 could reach as high as 303.7 F g−1 (206.5 F cm−3) in 6 M KOH electrolyte at 40 mA g−1.