Ion Redistribution and Rapid-Transfer Composite Protective Layer for Stable Lithium Metal Anodes

Abstract Uneven deposition and dendrite growth, which lead to capacity fading and short cycling life, are main obstacles that limit the application of Li metal anodes in Li metal batteries. Here, a composite protective layer composed of polyacrylonitrile (PAN), poly­(methyl methacrylate) (PMMA), SiO2 nanoparticles, and plasticizer is reported to promote a stable and dendrite-free Li metal anode. The robust layer (≈10 μm) coated on Cu or Li with high ionic conductivity and mechanical strength enables the uniform Li deposition due to the homogeneous Li ion distribution. As a result, the protected Li metal anode shows improved Coulombic efficiencies and cycling stability at various current densities. Full cells containing a LiFePO4 cathode and a protected Li anode show satisfying capacity retention (96.7% after 250 cycles) and rate capability, even with a limited amount of Li metal in the anode.