Preparation And Electrochemical Properties Of Electrode Materials For Supercapacitor Based On Cobalt Molybdenum Chalcogenides

Supercapacitors have the advantages of high power density,fast charge and discharge,and excellent cycle stability,which have already occupied an important position in the field of energy storage.However,their intrinsical low energy density severely limits the practical application in life.It is well known that assembling asymmetric supercapacitors can improve the voltage window of devices,thus significantly increasing their energy density.At the same time,cobalt molybdenum chalcogenide is a kind of typical pseudocapacitor electrode material,which exhibits high specific capacitance,good rate performance and cycle stability.Compared with other transition metal oxides,there are relatively few reports on cobalt molybdenum chalcogenide compounds.Therefore,the research has high research value and significance.Se and S,as cognate elements with O,not only have similar chemical properties but also much stronger metal properties.In this paper,cobalt molybdenum chalcogenide is taken as the research object,and the design of material and the construction of energy storage device are combined to develop supercapacitor electrode materials with better performance and more practical value.Co?OH?F nanowire arrays were synthesized on carbon fiber cloth by hydrothermal method.The synthesized?NH₄?₂MoS₄ was used as sulfur source and the CoMoS₄ hollow nanotubes were generated by anion exchange reaction with Co?OH?F.Then,in the standard three-electrode system,the core-shell CoMoS₄@Ni-Co-S nanotubes arrays are constructed by electrodeposition method,and the effects of different number of deposition cycles on the morphology and properties of the material are detailedly studied.Finally,the optimized CoMoS₄@Ni-Co-S hollow nanotubes electrode materials and activated carbon are assembled into an asymmetric supercapacitor,and a series of tests are carried out on the two-electrode system.CoMoS₄@Ni-Co-S can achieve 2208.5 F/g specific capacitance at 1 A/g and a capacitance retention rate of 91.3%for 5000 cycles at 3 A/g.The assembled CoMoS₄@Ni-Co-S//AC asymmetric supercapacitor delivers an energy density of 49.1 W h/kg at the power density of 800 W/kg.Meanwhile,the capacitance retention rate reaches90.3%after 10000 cycles.Cobalt nitrate and sodium molybdate were used as cobalt source and molybdenum source.Hydrazine hydrate was acted as reducing agent and nitrogen released from hydrazine hydrate was utilized as soft template with the self-assembly between CoSe₂ nanorods and MoSe₂ nanoparticles.CoSe₂/MoSe₂ hollow nanospheres were prepared by one-step hydrothermal method and annealing treatment.The effects of different proportions of cobalt and molybdenum on the morphology and properties of the electrode materials were carefully investigated.Finally,the optimized CoSe₂/MoSe₂ hollow nanospheres and activated carbon were assembled into asymmetric supercapacitors,achieving excellent electrochemical performance.The CoSe₂/MoSe₂ electrode material can deliver 1907.7 F/g specific capacitance at 1 A/g.The capacitance retention rate is 94.2%for 2000 cycles at 3 A/g.When the power density of the assembled CoSe₂/MoSe₂//AC asymmetric supercapacitor is 799.2W/kg,the energy density can reach as high as 51.84 W h/kg.At the same time,the capacitance retention rate is 93.4%after 10000 cycles.