Preparation And Electrochemical Properties Of Bimetallic Phosphide For Flexible Carbon Fiber

Supercapacitors(SCs)are considered to be one of the most promising high-performance power supplies in the 21st century.As the core part of the supercapacitor,the electrode can directly affect its performance.Therefore,the development of new electrode materials with excellent performance has become the focus of current research.It is a good idea to use a combination of activated carbon fiber and redox material to construct a composite electrode with high energy density and good flexibility.A common method is to mix the binder with the active material and prepare the composite electrode by direct coating.The method is complicated,and the prepared composite electrode has low capacitance,poor stability,and general mechanical properties.If the active material is directly supported on a flexible substrate by in-situ growth,a flexible composite electrode material having both excellent electrochemical properties and mechanical properties can be obtained.In this paper,the carbon networks(CNW)obtained by high-temperature carbonization of commercially available cotton fabrics shows good mechanical properties and electrical conductivity.As a substrate,a flexible composite electrode material was prepared by in situ growth of active material on its surface,and its electrochemical performance was characterized.CNW/NiCo2O4 composites with one-dimensional nanowire array morphology prepared by hydrothermal method were used as precursors,and sodium hypophosphite(SHP)was used as phosphorus source.The temperature was controlled to 300? by crystallization and phosphating The CNW/NiCoP composite material retains the nanowire morphology of the precursor,and the nanowire has a diameter of about 70?90 nm and a length of about 1.0 ?m.The CNW/NiCoP composite electrode has better rate characteristics.In the CV test,the capacitance retention rate was 60.8%,when the scanning rate was increased from 2 mV·s-1 to 20 mV·s-1.The maximum specific capacitance of the CNW/NiCoP composite electrode is 1167.2 F·g-1(current density 2 mA.cm-2).After 1000 consecutive charge and discharge(current density 10 MA·cm-2),the specific capacitance retention rate is 83.3%.For the first time,CNW/M11(HPO3)8(OH)6,M=(Ni+Co)(CNW/MHP)composites were prepared by one-step solvothermal method.The effects of reaction time,reaction temperature and SHP concentration in solution on the coating degree,crystal size and morphology of the composites were investigated.Under the reaction time of 16 h and the reaction temperature of 160?,a uniform and dense composite material can be obtained.When the concentration of SHP in the solution is 0.1 mol·L-1,the nanorod morphology is obtained,the diameter is about 400 nm,the length is about 2.0?m,the top of the rod is in the shape of a flower,which grows alternately.When the concentration of SHP is 0.2 mol·L-1 The nanosheet morphology is obtained.The nanosheet has a thickness of about 50 nm and a sheet width of about 1.0?2.0 ?m.The nanosheet has a fungus shape.In the electrochemical performance tests of rod-shaped and sheet-like CNW/MHP composite electrodes,both topographies showed good rate characteristics.At current density of 2 mA·cm-2,the maximum specific capacitance of the rod-shaped CNW/MHP composite electrode is 1357.5 F·g-1,while the sheet shape can reach 1513.6 F·g-1;at current density of 10 mA·cm-2,after 1000 cycles of charge and discharge,the capacitance retention of the rod-shaped and sheet-like composite electrodes were 82.4%and 84.3%,and had good capacitance stability respectively.The sheet-like CNW/MHP composite has good flexibility characteristics,can be stretched,curled,twisted,etc.,and its electrochemical properties after stretching have not changed significantly.This paper focuses on the study of the influence of experimental parameters on the preparation of composite materials based on CNW,in order to obtain an excellent flexible composite electrode with electrochemical performance.The first successful preparation of bimetallic hydroxy salt phosphate composites,and the study of the best synthesis conditions,laid the foundation for further research in the future.