ABSTRACT 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.
Song et al. (Sat,) studied this question.