Synthesis And Supercapacitive Performance Of Cobalt-Nickel-Based Nanomaterials

As a kind of high power density storage device,supercapacitor has been widely studied and concerned.However,its low energy density limits its application.It is one of the important means to improve the energy density of supercapacitor by designing the microstructure of electrode material and improving its specific capacitance.Among them,cobalt-nickel based compounds have become one of the research hotspots of electrode materials for supercapacitors due to their high specific capacity and low price.However,cobalt-nickel based compounds have some problems such as poor electrical conductivity,unstable structure and easy stacking.In this paper,on the one hand,cobalt nickel-based oxide and cerium oxide were combined to improve the conductivity of the material,on the other hand,Co_1-XS/Ni₃（NO₃）₂（OH）₄ composite was constructed by secondary solvothermal method to improve the structural stability of cobalt nickel-based materials.The fabricated composites showed high pseudocapacitance and cyclic stability.The details are as follows:A CeO₂/Co_1.29Ni_1.71O₄ material combining nanosheets and nanorods was in situ grown on the surface of inexpensive three-dimensional porous nickel foam by one-step hydrothermal and calcination method.Ceria exhibits a large number of oxygen vacancies in the composite,which significantly improves the conductivity of nickel-cobalt oxides.The optimal CeO₂/Co_1.29Ni_1.71O₄ material was obtained by adjusting the ratio of Ce and Ni-Co.The prepared electrode material was cycled 4500 times at a current density of 50 m A cm^-2 with a capacity retention of 93.10（4）and a maximum specific capacitance of 1.90 F cm^-2.The water-based asymmetric supercapacitor assembled with activated carbon has an energy density of 41.42 Wh kg^-1 at a power density of 400 W kg^-1.Secondly,Co_1-XS nanoparticles with high specific capacitance were loaded on Ni₃（NO₃）₂（OH）₄ with multiple active sites to effectively solve the problems of agglomeration of nanoparticles and stacking of nanosheets.The composite Co_1-XS/Ni₃（NO₃）₂（OH）₄ 3d material not only has high electrical conductivity,but also shows high specific capacity.The electrode polarization of Ni₃（NO₃）₂（OH）₄ was reduced by the better charge-discharge performance of Co_1-XS.The Co_1-XS/Ni₃（NO₃）₂（OH）₄ composite showed an ultra-high specific capacitance of 2576 F g^-1 at the current density of 1 A/g,and the capacity retention rate of the assembled asymmetric supercapacitor was 68.75（4）after 3000 cycles.The above structure design provides a good idea for the construction of electrode materials for supercapacitor.