Preparation And Supercapacitive Properties Of The Bimetallic Ni-Mo-Based Electrode Materials

Supercapacitor can be treated as a very efficient energy storage device owing to the incorporation of both the high power output of traditional capacitors and high charge storage of commercial batteries,and its performances mainly depends on the electrode materials.Therefore,developing the high-performance electrode materials is a key breakthrough direction for supercapacitors.Transition metal compounds have attracted much attention to be used as supercapacitor electrode materials due to the high theoretical specific capacitance values.In this paper,the supercapacitor performances of bimetallic Ni-Mo compounds were studied,and some strategies were also performed to enhance their supercapacitor performances including material composition,structural regulation and self-supporting electrode.Meanwhile,many high-performace supercapacitor electrode materials were also prepared.The main research contents are as follows:（1）The NiMoO₄ was prepared by the chemical precipitation method,and exhibited the specific capacitance of 552 F/g at 0.25 A/g.In order to further improve its capacitance performance,the NiMoO₄/g-C₃N₄ composite was synthesized by using g-C₃N₄ as the substrate.The specific capacitance of obtained NiMoO₄/g-C₃N₄ composite can reach 1275F/g at 0.25 A/g.In addition,the assembled NiMoO₄/g-C₃N₄//r GO hybrid supercapacitor can exhibit the energy density of 46 Wh/kg at a power density of 150 W/kg and the capacitance retention of 70%after 4000 cycles.（2）The NiMoS₄ was prepared by the solvothermal method,and its structure was adjusted by adding NH₄F to obtain NiMoS₄-A.The specific capacitances of NiMoS₄ and NiMoS₄-A are 580 F/g and 1137 F/g respectively at a current density of 0.5 A/g,higher than that of NiMoO₄,which is attributed to the fact that metal sulfides are superior to corresponding oxides in the conductivity and capacitance performances.In addition,the assembled NiMoS₄-A//AC hybrid supercapacitor can exhibit the energy density of 25Wh/kg at a power density of 94 W/kg,and the capacitance retention of 80%after 5000cycles.（3）The porous sponge-like NiMoS₄/Ni foam self-supporting electrode was prepared by the solvothermal method,and can be directly used as the supercapacitor electrode.The specific capacitance of NiMoS₄/Ni foam can reach 1680 F/g at 0.75 A/g,superior to traditional NiMoS₄ electrode,which is owing to the absence of the binder in the self-supporting electrode that impedes electron/ion migration.In addition,the hybrid supercapacitor NiMoS₄/Ni foam//AC was assembled and exhibited the energy density of32 Wh/kg at a power density of 94 W/kg,and the capacity retention of 84%at 8000cycles.In summary,several types of bimetallic Ni-Mo-based electrode materials were developed in this paper with inexpensive and readily available Ni and Mo salts as raw materials,which have high supercapacitive performance after performance regulation and reference value in the field of preparation of energy storage materials.