Electrochemical Performance Of 3D Porous Current Collectors For Li Metal Anodes By Loose Powder Metallurgy Method

With the rise of electric vehicles and the increasing demand for new electronic devices,Li metal is regarded as the next generation of advanced Li anode materials.However,problems including unstable interface and the growth of Li dendrite seriously hinder the development of Li metal.Compared with other strategies,the application of3D porous current collector can restrain Li dendrite and volume expansion more directly or effectively.However,because of the uneven Li metal deposition,the Coulombic Efficiency(CE)of 3D current collector is generally low.Also,the electrode materials are mostly in powder materials,which require homogenization,coating,slicing and so on.Therefore,it is of great significance to develop a 3D porous current collector with simple preparation process and high CE.In order to solve the problems including complex preparation process and 3D current collector'low CE,the structural design strategy and loose powder metallurgy method are used to prepare 3D porous Ni loaded with Ni(OH)₂(3D Ni@Ni(OH)₂)and covalently bonded CNTs/graphene foam(LPM-3D rebar GF)current collector which can guide Li⁺deposition behavior and promote uniform deposition.The preparation process,electrochemical performance and working mechanism of 3D Ni@Ni(OH)₂ and LPM-3D rebar GF current collector were studied.Surface active oxygen of 3D Ni@Ni(OH)₂ current collector is thermodynamically favorable for Li atom adsorption,which can promote uniform Li metal deposition.The 3D metal skeleton can not only have confinement effect,but also efficiently improve conductivity,showing a good electrochemical performance.In the LPM-3D rebar GF current collector,3D pipe-shape macroporous structure not only provide enough space for Li metal,but also play a good role in restricting the volume expansion.Through the first-principle calculation,it is proved that the addition of CNTs makes the electron cloud of 3D graphene migrate to the joint of CNTs and graphene,increasing active sites.CNTs also speed up the electronic transmission speed to reduce the local current density and inhibit the growth of the Li dendrite.LPM-3D rebar GF current collector have an excellent cycle life(80h)under high current density(15 m A cm^-2)and high specific area capacity(15 m A hcm^-2).Even at large specific area capacity of 30 m A hcm^-2,it can stabilize more than 90cycles with more than 98%CE and high mass specific capacity(2209 m A hg^-1).This work will provide a simple and valid method for the structural design and preparation of 3D porous current collector with active sites,and has a guiding significance for Li metal anode current collector at large current density and high areal capacity.