High‐Performance Solid‐State Lithium Batteries via Dipole‐Matching: Enabling Compact Polymer Microstructure and Stable Interfaces

Solid polymer electrolytes (SPEs) show great promise for solid‐state lithium metal batteries but face challenges due to inherently slow ion transport and interfacial instability. In this work, we propose a dipole‐matching strategy to engineer an SPE with a compact microstructure and stabilized interfaces. Through combined theoretical and experimental studies, we identify a molecular additive, such as 3,5‐bis(trifluoromethyl)benzoic acid (N‐CFF), that promotes rapid and uniform nucleation and directs phase alignment via dipole interactions with polymer chains, resulting in a compact microstructure conducive to rapid lithium‐ion transport and homogeneous deposition. Simultaneously, the dipole‐matched N‐CFF creates an electron‐rich environment that facilitates the formation of a LiF‐rich solid electrolyte interphase, effectively suppressing lithium dendrite growth. Employing this strategy, we fabricate Li||LiFePO 4 solid‐state batteries that deliver ultra‐long cycle life (90% capacity retention after 3000 cycles), exceptional low‐temperature and rate performance, as well as improved thermal safety. This work offers a comprehensive interface and microstructure co‐design approach to promote the development and application of high‐performance solid‐state batteries.