Optimized electrolytic carbon and electrolyte systems for electrochemical capacitors

Electrochemical reduction of a molten Li₂CO₃-Na₂CO₃-K₂CO₃ eutectic is used to produce highly amorphous carbon with considerable oxygen functionalization in a process focusing on the conversion of CO₂ to value-added carbon. Electrochemical characterization of materials using multiple techniques in different electrolytes allowed for the optimization of these materials as electrochemical capacitor electrodes. Variation in capacitive performance of the investigated materials has been provided based on their physical characteristics. The synthesized carbons are hybrid materials, showing both pseudocapacitive and electric double layer contributions to the total performance. Annealing under nitrogen at 800 °C is shown to widen pores in the carbon material, resulting in an increase in medium scan rate (5-10 mV.s^-1) capacitance. A stable specific capacitance of 425 F.g^-1 is obtained at 5 mV s^-1 in 0.5 M Na₂SO₄ after 1000 cycles.