Protective Layer Structure Regulation And Electrochemical Performance For Li Metal Anode

Li metal rechargeable batteries have attracted much attention due to their high energy density exceeding 500 Wh kg^-1.However,due to the extremely high reactivity of Li metal,it is extremely easy to form lithium dendrites and“dead Li”during the cycle,making the battery safe problems such as hidden dangers and low Coulomb Efficiency.At present,protection methods for Li metal anodes are mainly divided into two categories:in-situ method and ex-situ method.Among them,the ex-situ method builds a protective layer on the Li metal anodes outside the battery,and its composition is more uniform and controllable.Therefore,in this work,we used an ex-situ method to construct a uniform and fast Li⁺transporting protective layer on the surface of the Li metal anodes,which significantly improved the interface stability of Li metal and strengthened the electrochemical performance of the Li metal battery.First,the the Li metal is reacted with a solution prepared by a fluorine-containing solvent and a Li salt to form a protective layer(PL@Li)rich in LiF and coexisting inorganic substances such as Li₃N and Li₂S on the surface of the Li metal.Compared with the original Li metal,the inorganic substances such as LiF,Li₂S and Li₃N in the protective layer can induce the rapid and uniform deposition of Li⁺,and the composition of the protective city is evenly distributed,which can reduce the stress caused by the difference in the transmission rate of lithium ions in the protective layer.Cause damage to the protective layer.At a current density of 0.5 m A cm^-2,the PL@Li-based symmetrical battery can achieve a stable cycle of1900 hours while the polarization voltage is maintained at 40 m V,showing good cycle stability.Secondly,GO-ADP-Li₃ was synthesized by amidation reaction between GO and ADP-Li₃,and GO-ADP-Li₃ was added as a functional filler to the solid polymer electrolyte(SPE).GO-ADP-Li₃ increases the Li⁺conductivity of Li-GO-SPE by increasing the transmission path of Li⁺in the material and reducing the crystallinity of the polymer.Li-GO-SPE was coated on the surface of a 100?m Li foil as a Li metal surface protective layer(Li-GO-SPE@Li),and under actual conditions,the 0.2 Ah pouch full battery assembled with Li-GO-SPE@Li?NCM811 has a coulombic efficiency of 99.8%and a capacity retention rate of 78.4%after 150 cycles.