Construction Of Lithiophilic Skeleton And Research Of Electrochemical Behavior For Li Metal Anode

Rechargeble Lithium(Li)metal batteries have attracted broad scientific and technological interest because of its most negative electrode potential and lowest electrochemical equivalent.However,the exiting challenges of volume change,ruptured solid electrolyte interphase(SEI)and dendrites growth during Li plating/stripping are hindering the application of Li metal anode from the market.Constructing a three-dimensional(3D)conductive skeleton for Li metal anode is currently an effective method to alleviate the volume expansion during the Li deposition,but the Li dendrites has not been restrained.In this paper,from the perspective of the improved "lithiophilicity" for the 3D conductive skeleton,the uniform and dendrites-free deposition behavior of Li can be obtained by simultaneously improved electrons and Li ions conductivity,so that Li metal batteries have higher Coulombic efficiency and longer cycling life.The main research contents and conclusions are as follws:1.Preparation and electrochemical properties of the 3D Cu electrode decorated by CuO nanoflowers.The 3D Cu@CuO electrode was prepared by one-step in-situ oxidization of the 3D Cu mesh.A new type of composite Li metal anode is obtained by press the 3D Cu@CuO electrode on the Li wafer.Cu mesh can effectively alleviate the volume change during Li plating/stripping,while CuO nanoflowers can highly improve the Li deposition behavior and prompt Li ions diffuse more uniformly.The performance of symmetry-cells show that the 3D Cu@CuO/Li anode has lower deposition overpotential and better cycling stability than the 3D Cu/Li anode.Compared with the Li wafer and 3D Cu/Li anodes,the 3D Cu@CuO/Li anode can improve the initial discharge specific capacity of the LiFePO4 full-cell at 0.5 C from 141.46 mAh g-1 and 144.38 mAh g-1 to 153.99 mAh g-1,respectively.Studies show that CuO nanoflowers facilitate Li depositied on the 3D Cu@CuO skeleton rather than in the cavities,thus a more reversible Li plating and stripping behavior can be achieved.2.Application of the 3D Cu mesh modified by the PANI microsheets in the Li metal anode.The modified 3D Cu@PANI(3DCMP)electrode was prepared via in-situ polymerizing PANI on the 3D Cu mesh(3DCM)surface,excellent electrons and ions conductivity can effectively reduce the Li deposition barrier.The results show that the Coulombic efficiency(CE)and cycling stability of the 3DCMP electrode are better than the 3DCM electrode.The LiFePO4 full-cell shows that the capacity retention of the 3DCMP/Li anode is also better than the 3DCM/Li and Li wafer anodes.The initial discharge specific capacity of the 3DCMP/Li anode at 4 C was 134.13 mAh g-1.Compared with the "island growth" pattern on the Li wafer and 3DCM/Li anode,the amino-nitrogen atoms of PANI on the 3DCMP electrode can induce Li ions gathered and deposited along the skeleton orderly,which can greatly alleviate the dendrites Li formation and show a more excellent Li plating and stripping performance.