Well-coordinated bimetal sulfide MnS/Cu2S/C composite for high performance supercapacitors

Supercapacitor is one of well-known energy-storage devices. However, the electrode materials still restrict its performance and reduce its practical value due to low capacitance or high cost. Therefore, it is of vital importance to pursue the cheap electrode materials with high performance for the next generation supercapacitor. Herein, a series of bimetal sulfide MnS/Cu2S/C composite materials were synthesized by hydrothermal reaction and the subsequent calcination with expired manganese gluconate and copper gluconate as the starting materials. Moreover, the effect of Cu2S's content on the microstructure and capacitance of MnS/Cu2S/C bimetal sulfides was further investigated. All the composites showed the well-organized morphology of about 3 nm metal sulfide nanoparticles embedded in the carbon microspheres with a diameter of about 6 mu m. When the feeding ratio was 2:1, the reversible specific capacitances of 2MnS/Cu2S/C (MCS-2) in the three-electrode and two- electrode systems were as high as 1206 F/g and 116 F/g at 1.0 A/g, respectively, higher than those of other samples. The synergistic effect of the bimetal sulfides and the joint contributions of high conductivity and low capacitance of Cu2S may be responsible for the desirable high supercapacitance. Additionally, the successful conversion of expired gluconates to the useful electrode materials in this work highlighted the ecological benefits and the positive effect on the environmental protection and the resource conservation.