CoMoO4/bamboo charcoal hybrid material for high-energy-density and high cycling stability supercapacitors

Abstract

Here we report a supercapacitor with high energy density and high cycling stability using low-cost and environmentally friendly CoMoO₄/bamboo charcoal (BC) hybrid materials as the cathode. The hybrid materials were fabricated via a one-pot solvothermal reaction followed by an annealing process. The optimized CoMoO₄/BC hybrid material has a specific surface area of 74.4 m² g⁻¹, being 1.7-fold higher than that of the CoMoO₄ precursor. The hybrid electrode shows a high specific capacitance of 422.3 F g⁻¹ at 0.5 A g⁻¹ and 304.8 F g⁻¹ at 50 A g⁻¹. The as-assembled CoMoO₄/BC||activated carbon supercapacitor exhibits a high energy density of 56.7 W h kg⁻¹ and 18.3 W h kg⁻¹ at a power density of 785 W kg⁻¹ and 40 000 W kg⁻¹, respectively. Furthermore, it also shows excellent long-term cycling stability. Subjected to 40 000 cycles of charge–discharge test at a current density of 50 A g⁻¹, there is only about 10% capacitance loss (occurring only during the first 5000 cycles). This excellent electrochemical performance is ascribed to the covalent C–Mo and C–O bonds formed between CoMoO₄ and BC as well as the porous feature of the hybrid material, which provide highways for electron transfer and ion transportation within the electrodes and at the electrode–electrolyte interface.