Yameng Yin, Qinxia Liu, Zhiyuan Zhang, Weixiao Wang, Cunyuan Pei, Fangyu Xiong, Jinghui Chen, Qinyou An, Cai‐Hong Yang, Dong‐Sheng Li
ABSTRACT The instability of the cathode electrolyte interface (CEI) under high voltage and elevated temperature poses a major challenge to the practical application of Na 3 V 2 (PO 4 ) 2 O 2 F (NVOPF) cathodes in sodium‐ion batteries (SIBs). To overcome this issue, we introduce a dual‐functional AlF 3 coating that effectively stabilizes the interface while improving bulk electronic conductivity. The AlF 3 ‐modified NVOPF@C exhibits exceptional cycling stability at 55°C, maintaining 84.9% capacity after 1000 cycles at 10 C in half cells and 96.8% at 5 C in full cells using hard carbon anodes. Detailed characterization reveals that the AlF 3 coating promotes the formation of a robust, inorganic‐rich CEI, primarily composed of a NaF/AlF 3 /NaAlF 4 ternary fluoride composite. This newly constructed CEI layer not only acts as a protective barrier to suppress detrimental interfacial side reactions but also serves as an efficient ionic conductor to facilitate Na + diffusion. In addition, the AlF 3 coating induces the creation of F─Al─O bridging bonds with surface oxygen groups, which collaborate with carbon nanotubes to establish a highly continuous conductive network that enables efficient electron transfer. These findings underscore the crucial significance of constructing a stable inorganic‐dominated CEI and continuous conductive pathways for developing high‐rate and thermally stable SIBs.