Boosting specific capacitance of Mo-Co-(S,O) electrode via a synergistic optimization strategy

Abstract

Low electrical conductivity and insufficient active sites of Co-based binary metal oxides or sulfides hamper their practical specific capacitance especially at high current densities. In the current work, we provide a novel synergistic optimization strategy including P doping and constant-current-charge activation (CA) to greatly improve the specific capacitance of sulfur and oxygen-containing Mo-Co binary compounds (Mo-Co-(S,O)) electrode. The synergistic effect of the P doping and activation not only increases the electrical conductivity but also improves the electroactive sites. As a result, the optimized Mo-Co-(S,O)/P-CA electrode shows exceptional specific capacitance (∼9.64 F cm−2/2931 F g−1 at 12.5 mA cm−2), approximately 20 times the pristine Mo-Co-(S,O). Moreover, an asymmetric supercapacitor prepared with Mo-Co-(S,O)/P-CA cathode and conductive carbon cloth achieves a high energy density of 0.61 mWh cm−2 at a power density of 4.25 mW cm−2, and outstanding cyclic performance with 121.6% of capacitance retention after 12,000 cycles.