Enhanced Rate Performance of Supercapacitor Electrode Using Hydrophilic Porous Carbon Synthesized from Polyvinylidene Chloride-Resin with CuO and Tetrahydrofuran

Carbon materials used as an electrode for aqueous supercapacitors should be synthesized with a porous structure and hydrophilic properties to facilitate the adsorption and desorption of electrolyte ions for charge storage. To enlarge the specific surface area, the porous morphology should contain micropores (diameter < 2 nm). Mesopores (diameter: 2 – 50 nm) should also be present for facile ionic transport. Hydrophilic carbon can be achieved by introducing hydrophilic functional groups on the surface. Here, hydrophilic porous carbon was synthesized by mixing a polyvinylidene chloride (PVDC) resin precursor with copper oxide (CuO) and tetrahydrofuran (THF), followed by heat treatment at 750°C. CuO acted as a template during the heat treatment, creating large mesopores. The generated HCl from PVDC combined with CuO to form CuCl2, contributing to the micropore formation. THF played a role in introducing hydrophilic functional groups on the carbon surface, to promote the adsorption of aqueous electrolyte ions. The activated carbon synthesized using CuO and THF exhibited a specific capacitance of 90 F g-1 at a scan rate of 5 mV s-1 in 0.5 M K2SO4 electrolyte. The synthesized activated carbon demonstrated excellent rate capability, retaining 82% of its capacitance at 10 times faster charging rate (50 vs. 5 mV s-1).