Study On Electrochemical Performance Of Bimetallic Cobalt Nickel Selenide-Conducting Polymer Composites

Cobalt-nickel bimetallic oxides had been extensively studied as electrode material for supercapacitors.However,the poor conductivity of cobalt-nickel bimetallic oxides usually resulted in the limited energy storage characteristics.In this paper,selenization was used to replace oxidation,then the material was combined with conductive polymer,to improve the conductivity of the material.Then the cobalt-nickel bimetallic selenide-conductive polymer composite material was obtained.In order to explore the impact of conductive polymer shell on the electrochemical performance of the composite material,the cobalt nickel bimetallic selenide was compounded with different conductive polymers.Firstly,Cobalt nickel bimetallic selenide nanotubes were grown on Ni foam by a two-step hydrothermal method.Then a layer of polypyrrole（PPy）shell was coated on the surface of the cobalt nickel bimetallic selenide nanotubes by constant potential deposition,and the core-shell structure was formed,the cobalt-nickel bimetallic selenide-polypyrrole composite electrode material grown on Ni foam was obtained.The results showed that the electrode had a high area specific capacitance of 13.27 F cm^-2 at a current density of 5 m A cm^-2.After 1000 cycles at a current density of 30 m A cm^-2,it still remained 92.63%of the initial specific capacitance,illustrating the excellent electrochemical performance.Additionally,the addition of PPy shell increased the specific capacitance of the material,improved the conductivity of the material,provided a fast transmission path for electrons and ions,and sped up the charge transfer rate and ion diffusion rate.Secondly,in order to explore the effect of different conductive polymer shells on the electrochemical performance of the electrode material,the composite electrode material of cobalt nickel bimetallic selenide-polyaniline grown on Ni foam was formed by a two-step hydrothermal method combined with electrodeposition,and a core-shell nanotube structure was formed.The polyaniline（PANI）shell provided further enhanced conductivity,a faster electron transmission path,and increased pseudocapacitance.The material showed a high area specific capacitance of 12.26 F cm^-2 at a current density of 10 m A cm^-2.In addition,it had good cycle stability.The capacitance remained 95.4%after 1000 cycles at a current density of20 m A cm^-2.Finally,the research showed that both the polypyrrole（PPy）and polyaniline（PANI）shells had promoted the conductivity,specific capacitance,and cycle stability of the composite material.It was proved that combining the cobalt nickel bimetallic selenide with the conductive polymer was a significant way to improve the electrochemical performance of the material.