Interface Engineered Electrolyte Design Strategy for Ultralong‐Cycle Solid‐State Lithium Batteries Over Wide Temperature Range

Abstract Achieving stable operation under a wide temperature range is the direction of development for the practical application of solid‐state lithium batteries. However, the suboptimal ionic conductive properties exhibited by the electrolyte, the uncontrolled growth of lithium dendrites due to the deposition of inhomogeneous Li + and the potential safety hazards caused by unstable interfaces have seriously affected the cycle life of the battery at extreme temperatures. Herein, a fluoropolymer‐containing plastic‐crystal‐based electrolyte (FPCE) has been developed by means of a structural engineering process, with the objective of optimizing the solid electrolyte interface (SEI). The integration of solvent structure simulation and experimental results demonstrates that FPCE regulates Li + transport, promotes the in‐situ formation of the LiF‐rich inorganic–organic hybrid SEI, and enhances the overall stability of the battery. Consequently, FPCE assists in preserving stable LFP|FPCE|Li cells cycling, with 5000 cycles at a high current density of 10 C and an average capacity decay rate of merely 0.00448% per cycle. Furthermore, the Ah‐level pouch cells demonstrate the capacity to operate stably within the temperature range of −10 to 80 °C. This study provides a valuable strategy for the design of wide‐temperature solid‐state polymer electrolytes.