Preparation And Electrochemical Properties Of Porous Copper Collector For Lithium Ion Battery

The collector is an important part of the lithium ion battery.The collector can not only carry the active materials,but also collect and output the current generated by the electrode active materials,which helps to reduce the internal resistance of the lithium ion battery and improve the coulomb efficiency,cycle stability and rate performance.However,the traditional smooth copper foil collector has problems such as weak adhesion with the active material,easy corrosion by organic electrolyte,and large electrochemical impedance,which lead to the problems of low actual specific capacity,large irreversible capacity loss for the first time,and poor rate discharge performance of the anode material coated on it.Therefore,in this paper,three-dimensional porous copper collector was prepared by electrochemical dealloying method and applied to lithium metal anode.Firstly,three electrochemical methods,constant current method,constant voltage method and square wave cyclic pulse method,were used to etch copper zinc alloy to prepare three-dimensional porous copper collector;Compared with the chemical etching method,the porous copper collector prepared by the electrochemical etching method has a uniform,smooth and dense network structure,and its strength is significantly improved,thus improving the stability of the electrode in the cycle process;At the same time,the porous copper collector prepared by electrochemical etching method can well maintain the electronic conductive network,promote electronic conduction,and help to improve the electrochemical performance;The electrochemical etching method is simple and feasible,which is expected to realize the large-scale production of three-dimensional porous copper collector fluid.Secondly,the effects of current intensity,voltage intensity,electrolyte concentration,reaction time and other factors on the dealloying of copper zinc alloy are systematically analyzed,and the reaction mechanism in the dealloying process is deeply discussed.XRD,SEM,EDS and other characterization methods were used to analyze the morphology changes and component distribution during the process of dealloying.Through the change of tensile strength,pore diameter and porosity,the change rule of mechanical properties and structure of materials in the process of dealloying is explored.Finally,from the perspective of practical application of lithium metal anode,the above three electrochemical methods were respectively prepared Li@3D It is found that the porous copper collector can effectively inhibit the growth of lithium dendrite when Cu electrode is applied to the semi battery.The main reason is that the uniform and continuous three-dimensional porous copper collector structure gives lithium more deposition space;The larger specific surface area of the three-dimensional porous copper collector can reduce the current density,avoid the charge concentration,which is conducive to the homogeneous deposition of lithium metal in the channel and inhibit the formation of lithium dendrites;At the same time,the uniform and continuous three-dimensional porous copper collector can induce the formation of high-quality SEI film,avoid the rupture and continuous formation of SEI film,and improve the coulomb efficiency of the battery;Moreover,the compact structure with good mechanical properties promotes the cycle stability of lithium metal battery.Among them,the collector prepared by square wave pulse circulation method has the best long-term circulation stability,which can achieve stable operation after 400 hours,and the coulomb efficiency is the highest,which is maintained at more than 98% after150 cycles.