Design,Preparation And Performance Study Of Functional Layer On Anodic Current Collector Surface For Lithium Ion Battery

Lithium-ion batteries(LIBs)have attracted the attention of many scholars in recent decades due to their great potential for applications in portable electronic devices,new energy vehicles and industrial storage.With the continuous progress of the industrial process,higher requirements are put forward for the high-performance anode materials of LIBs.The traditional graphite anode material is limited by its own lower theoretical capacity and will be gradually eliminated.Although the transition metal oxides own higher theoretical specific capacity,it also has its disadvantages such as severe volume expansion effect,low cycle life and bad cyclic stability performance.To solve the above problems,a new type of copper-based current collector with surface functional structure was used to prepare the high-performance anode materials in this paper.The preparation of the current collector,characterization of the material properties and the influence on the cycling performance of LIBs were systematically studied.Specifically,the main contents include the following:(1)Physical properties and electrochemical characterization of the self-made electrodeManufacturing copper fiber sintered felt via metal fiber multi tooth cutting and high temperature solid phase sintering.Then,its surface is super-hydrophilically modified by alkali-assisted surface oxidation.Finally,the binding force between the fiber felt collector and the active material,the effect of deposition of CuO functional layers on lithium ions diffusion coefficients and the accuracy verification of MCMB/CuO/Cu equivalent circuit model were studied.(2)Electrochemical performance study of pure MCMB or CuO anode materialsAssemblng the battery with the novel self-made fiber felt as collector and pure MCMB or pure CuO as the active material.First of all,the influence of the surface modification on the performance of the battery is analyzed.Secondly,the influence of the type of current collector,the porosity of fiber mat and the deposition time of CuO functional layer on the battery performance is studied.Finally,the electrochemical reaction mechanism was revealed via cyclic voltammetry and AC impedance method.(3)Preparation and electrochemical performance test of MCMB/CuO/Cu anode materialIn this section,the above MCMB and CuO active materials are organically combined to prepare a novel MCMB/CuO/Cu hierarchical composite material.The super hydrophilicity of the CuO micro-layer enhances the binding force between the aqueous active material slurry and the negative electrode current collector.At the same time,the rough porous surface of CuO micro-clusters provides a charge-discharge expansion buffer structure for MCMB spheres,effectively protecting the lattice structure of MCMB from being destroyed by severe volume expansion.Interestingly,the pseudo-capacitance reaction between the CuO and Li~+in electrolyte can be conducted to achieve the merger promotion of specifc capacity and specific energy for LIBs in this project.