In Situ Constructing Robust and Highly Conductive Solid Electrolyte with Tailored Interfacial Chemistry for Durable Li Metal Batteries

Abstract Employing nanofiber framework for in situ polymerized solid‐state lithium metal batteries (SSLMBs) is impeded by the insufficient Li + transport properties and severe dendritic Li growth. Both critical issues originate from the shortage of Li + conduction highways and nonuniform Li + flux, as randomly‐scattered nanofiber backbone is highly prone to slippage during battery assembly. Herein, a robust fabric of Li 0.33 La 0.56 Ce 0.06 Ti 0.94 O 3‐δ /polyacrylonitrile framework (p‐LLCTO/PAN) with inbuilt Li + transport channels and high interfacial Li + flux is reported to manipulate the critical current density of SSLMBs. Upon the merits of defective LLCTO fillers, TFSI − confinement and linear alignment of Li + conduction pathways are realized inside 1D p‐LLCTO/PAN tunnels, enabling remarkable ionic conductivity of 1.21 mS cm −1 (26 °C) and t Li+ of 0.93 for in situ polymerized polyvinylene carbonate (PVC) electrolyte. Specifically, molecular reinforcement protocol on PAN framework further rearranges the Li + highway distribution on Li metal and alters Li dendrite nucleation pattern, boosting a homogeneous Li deposition behavior with favorable SEI interface chemistry. Accordingly, excellent capacity retention of 76.7% over 1000 cycles at 2 C for Li||LiFePO 4 battery and 76.2% over 500 cycles at 1 C for Li||LiNi 0.5 Co 0.2 Mn 0.3 O 2 battery are delivered by p‐LLCTO/PAN/PVC electrolyte, presenting feasible route in overcoming the bottleneck of dendrite penetration in in situ polymerized SSLMBs.