An Elastomeric Lithium‐Conducting Interlayer for High‐Performance LATP‐Based Lithium Metal Batteries

Abstract In response to the critical challenges of interfacial impedance and volumetric changes in Li (1+x) Al x Ti (2‑x) (PO 4 ) 3 (LATP)‐based lithium metal batteries, an elastomeric lithium‐conducting interlayer fabricates from fluorinated hydrogenated nitrile butadiene rubber (F‐HNBR) matrix is introduced herein. Owing to the vulcanization, vapor‐phase fluorination, and plasticization processes, the lithium‐conducting interlayer exhibits a high elasticity of 423%, exceptional fatigue resistance (10 000 compression cycles), superior ionic conductivity of 6.3 × 10 −4 S cm −1 , and favorable lithiophilicity, rendering it an ideal buffer layer. By integrating the F‐HNBR interlayer, the LATP‐based lithium symmetric cells demonstrate an extended cycle life of up to 1600 h at 0.1 mA cm −2 and can also endure deep charge/discharge cycles (0.5 mAh cm −2 ) for the same duration. Furthermore, the corresponding lithium metal full cells achieve 500 cycles at 0.5 C with 98.3% capacity retention and enable a high‐mass‐loading cathode of 11.1 mg cm −2 to operate at room temperature.