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

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.