Electrochemical performance of graphitized carbide-derived-carbon with hierarchical micro- and meso-pores in alkaline electrolyte

Graphitized carbide-derived-carbon (CDC) with hierarchical micro- and meso-pores is synthesized by chlorination of titanium carbide powder at 1000 °C. The produced CDC has many bilayer graphenes and some narrow graphite ribbons, which contributes a large amount of micropores (∼1.35 nm) and some mesopores. Although hierarchical pore is an attractive structure for supercapacitor, the low hydrophilicity of the graphitized CDC leads to poor electrochemical performance in alkaline electrolyte. The specific capacitance of the CDC in KOH aqueous electrolyte is only 5 F g^-1. A strategy that adding ethanol to alkaline electrolyte is presented to improve its surface wettability. The specific capacitance of the graphitized CDC in KOH aqueous electrolyte with addition of ethanol increases to 60 F g^-1 at a scan rate of 20 mV s^-1. The optimal content of ethanol in KOH electrolyte is 10 wt.%. In addition, cyclic voltammogram curve can maintain a quasi-rectangular shape well even at a scan rate of 500 mV s^-1 and the retention rate of the specific capacitance is about 70%. The specific capacitance is stable at high current density (e.g. 1 A g^-1), and almost no performance degradation is observed after 8000 consecutive cycles.