Preparation And Electrochemical Properties Of 3D Porous Cu Current Collector For Lithium Metal Anode

In recent years,the rapid development of various kinds of electronic products and new energy vehicles requires the development of high-energy density batteries urgently.Lithium metal anode gradually attracted the interest of the researchers due to its advantages of high theoretical specific capacity(3860 mAh g^-1)and the low voltage platform（-3.04 V vs standard hydrogen electrode）.Lithium metal anode can be widely used in lithium batteries,lithium sulfur battery and lithium air battery.However,shortcomings of lithium metal anode restrict its commercial application.Lithium dendrite gradually grows and its volume expansion is obvious during long cycling of battery,which not only causes the capacity attenuation but also leads to the battery short circuit,thermal runaway and other security issues.In view of the above problems,3D porous copper was prepared and applied as current collector of Li metal anode to promote its practical application.In this paper,using the commercial copper-zinc alloy as raw material,the linear sweep voltammetry electrochemical dealloying method is used to precisely regulate the three-dimensional porous copper structure.Compared to chemical dealloying method,the porous copper prepared by electrochemical etching method has a uniform,smooth and compact network structure,which helps to enhance the strength and the stability of the electrode during cycling.At the same time,it can maintain a good electronic conductive network,which promotes the conduction of electrons and improves the electrochemical performance.In addition,the method is simple and easy to use commercial Cu-Zn alloy tape as raw material,and it is expected to realize the large-scale production of 3D porous copper current collector.Secondly,based on the practical application of lithium metal anode,the Li@3D Cu anode was prepared and used in half battery,which can effectively inhibit the lithium dendrite growth.This inhibition of lithium dendrites is mainly because that a homogenous and continuous porous structure contributes to more lithium deposition space and large surface area,which avoids the charge concentration so as to inhibit the formation of lithium dendrites.At the same time,the 3D porous copper current collector with a uniform,smooth and compact network structure induces formation of high a quality SEI film,which avoids the rupture and continuous generation of SEI film,thus coulombic efficiency is enhanced.Moreover,the compact structure has good mechanical properties,which promotes the cycling stability of the lithium metal battery.The half cells can stably cycle for 400 hours without short circuit.In the end,the 3D porous copper current collector was further modified by several methods,which were found to be beneficial to inhibiting the Li dendrite growth.The first is that the electrophilic modification of 3D porous copper by silver plating can induce the deposition of lithium and promote the smooth deposition of lithium.Secondly,the coating of the porous layer of graphene can construct more space for Li deposition and increase the energy density of the whole electrode.The third is that the polymer PEO coating can effectively improve the surface charge distribution,reduce the deposition lithium on the surface,and induce lithium to be more prone to deposit into the porous copper current collector.The modifications of the 3D Cu can further promote the future application of lithium metal anode.