Preparation Of Nickel-Molybdenum-Based Electrode Materials And Property For Supercapacitor

Supercapacitors have become a research hotspot due to their high power density,high cycle stability,rapid charge and discharge,and safety and environmental friendliness.The performance of electrode materials is one of the decisive factors affecting their performance.Transition metal molybdates show excellent performance in various energy storage fields due to their stable crystal structure,abundant redox reactions,simple preparation,high theoretical capacity,and environmental friendliness.Such as specific capacitance and rate performance is not ideal.In this paper,NiMoO4 is used as the substrate to modify and synthesize NiMo-based electrode materials through rational design of morphology,selenization and structure.The main work is as follows:(1)Nanomaterials with different morphologies were prepared by in situ growth of NiMoO4 on nickel foam by a hydrothermal method in an organic alcohol-water system.Studies have shown that the 3D network needle-like structure NiMoO4 prepared in the ethanol-water system has high specific capacitance,good rate performance and good cycling stability.543 C g-1(1207 F g-1),the capacity retention rate can reach 84.6%after 5 000 cycles at 5 A g-1.The asymmetric supercapacitor assembled with it as the positive electrode and activated carbon(AC)as the negative electrode exhibits an energy density of 29 Wh kg-1 at a power density of 750 W kg-1,and still has an energy density of 14 Wh kg-1 even when the power density is as high as 7500 W kg-1.(2)The NiMo selenide(NiMoSe)electrode material was prepared by using Se powder as the Se source and NiMoO4 as the precursor using the selenization strategy,and the morphology and structure of NiMoSe was regulated by adjusting the selenization concentration.The research results show that Se atoms and O atoms of the same main group are replaced by hexagonal sellenite(Ni0.85Se)phase,and Mo atoms form a NiMo solid solution in the Ni0.85Se lattice,which induces the occurrence of electronic structures around Ni and Mo.It has multiple chemical states and exhibits excellent Faradaic redox performance.NiMoSe(0.03)prepared at a selenide concentration of 0.03 mol L-1 has a specific capacity of 969 C g-1(2153 F g-1)at 1 A g-1 and was cycled for 5 000 at 5 A g-1,the secondary capacity retention rate was 76.6%.NiMoSe//AC possesses an energy density of 36 Wh kg1 at a power density of 800 W kg-1,and an energy density of 9 Wh kg-1 even at a power density of 8000 W kg-1.(3)Using the core-shell layered structure design,NiAl-LDH was in situ grown on the surface of the NiMoSe precursor material to obtain the NiMoSe@NiAl-LDH core-shell electrode material with a multi-level layered structure.The 3D rose-like NiAl-LDH covers the surface of NiMoSe nanoneedles to form a layered composite structure.Compared with NiAl-LDH and NiMoSe,the electrochemical performance of NiMoSe@NiAl-LDH material is significantly improved.The specific capacity is 1381 C g-1(3069 F g-1)at 1 A g-1,and the capacity retention rate is 85.2%after 5 000 cycles at 5 A g-1.NiMoSe@NiAl-LDH//AC has an energy density of 50 Wh kg-1 at a power density of 800 W kg-1,and still has an energy density of 16 Wh kg-1 even when the power density is as high as 8000 W kg-1.