ABSTRACT To address the critical challenges of poor ionic conductivity, insufficient interfacial stability, and narrow operating temperature range in all‐solid‐state lithium batteries (ASSLBs), this work develops a dynamic anion functionalization strategy to design and synthesize a new class of yttrium‐based rare‐earth halide solid‐state electrolytes (SSEs). It is found that the dynamic anions can not only statically modify the lattice but also undergo reversible dynamic migration during cycling, thereby transforming the traditional single‐cation conductor into a cation‐anion synergistic conductor, which significantly enhances the overall ionic conductivity. Furthermore, the dynamic anions facilitate a gradient LiF protection layer on the cathode side to improve high‐voltage compatibility and form a dense Li 3 N–LiF–LiI composite adaptive interphase on the anode side, effectively suppressing dendrites and stabilizing the interface. The assembled ASSLBs based on the dynamic anion strategy demonstrate stable operation across a wide temperature range from extreme cold (−30°C) to high temperatures (140°C), while delivering high specific capacity, long cycle life, and outstanding safety characteristics. Our findings establish a new paradigm for developing next‐generation ASSLBs capable of reliable operation under extreme conditions.
Li et al. (2026) studied this question.