Robust Nanoscale Anode Protective Layers toward Fast‐Charge High‐Energy‐Density Lithium Metal Batteries

Abstract Mechanically stable and structurally homogeneous lithium–electrolyte interfacial layers are crucial in stabilizing lithium (Li) anodes for practical Li metal batteries. Herein, an ultrathin (≈84 nm) and robust artificial protective layer is constructed with reactive two‐dimensional (2D) molecular brushes as building blocks. The artificial protective layer can in situ react with underlying Li metal to produce a nanoscale poly(lithium styrenesulfonate)‐grafted graphene oxide (GO‐ g ‐PSSLi) layer on the outermost surface and an infinite Li–Ag solid solution in the anode. The nanoscale GO‐ g ‐PSSLi layer well integrates a large number of single Li‐ion conducting PSSLi chains and 2D robust GO backbones, thereby enabling molecular‐level homogeneous and fast Li‐ion diffusion as well as remarkable mechanical strength. Meanwhile, the simultaneously formed Li–Ag solid solution is beneficial for rapid Li transport in the anode to reduce the Li nucleation barrier and facilitate homogeneous deposition of Li. With such artificial protective layers, a prototype pouch cell with a thin Li metal anode (50 µm) and a high‐loading cathode (21.6 mg cm −2 ) delivers an impressive cycle life of over 350 cycles with 69% capacity retention under harsh conditions. Remarkably, ultrahigh charging power density of 456 W kg −1 and energy density of 325 Wh kg −1 can be simultaneously achieved in an Ah‐level pouch cell.