Study On The Preparation And Electrochemical Energy Storage Performance Of Carbon And Nickel-based Phosphorous Compounds Composites

With the efficient utilization of renewable energy in the world and the rapid expansion of electric vehicle market,the importance of rechargeable battery/capacitor technology,especially super capacitor and alkali metal ion battery,has been steadily increased.In the past few years,super capacitors?SCs?,lithium-ion batteries?LIBs?and sodium ion batteries?SIBs?,as three important electrochemical energy storage devices,have the advantages of high-power density,high cycle life and can meet the specific application requirements.At present,lithium-ion batteries have occupied the market of portable electronic products,such as watches,mobile phones and laptops,which are also identified as the preferred energy sources for electric vehicles and fixed energy storage.Due to the Faraday charge transfer process involved in the electrochemical process of supercapacitors,transition metal-based materials can store more energy than carbon materials.In this paper,based on the study of transition metal compounds,combined with advanced carbon materials of different structures,using different phosphating processes,the carbon containing Ni-P metal compound composite materials were prepared,and their properties as electrode materials of different energy storage devices were studied.In addition to the addition of carbon materials,the effects of other doping elements,surface modification and other methods to enhance the electrochemical properties of metal phosphides were also studied.The specific research contents are as follows:?1?Ni₂P-Ni@N-doped carbon@graphene composite?Ni₂P-Ni@NC@G?was prepared by one-step solvothermal and ultrasonic process.It shows excellent electrochemical performance when used as electrode material of supercapacitor.At the current density of 1 A·g^-1,the specific capacitance reaches 2334.5 F·g^-1.The capacity retention rate of the composite material is more than 96%after 3000 charge discharge cycles.?2?Using CNT as conductive additive and CTAB modified composite method,Ni₂P@ACNT?CTAB?was prepared.As battery type SCs electrode material,it can not only be used as super capacitor material,but also as LIBs anode material.After 320cycles at current density of 0.2 A·g^-1,its specific capacity still reaches 1475 mAh·g^-1.?3?Furthermore,Ni-P bimetallic materials were prepared to further enhance the electrochemical properties of Ni₂P because of its two different metal atomic sites.Firstly,transition metal oxides were prepared,then phosphating and then self-assembled with go in solution,then reduced to O-NiCoP@rGO composite.At 1A·g^-1,O-NiCoP@rGO electrode can provide a specific capacitance of 1663.2 F·g^-1.