Achieving Ultrahigh‐Rate and High‐Safety Li+ Storage Based on Interconnected Tunnel Structure in Micro‐Size Niobium Tungsten Oxides

Abstract Developing advanced high‐rate electrode materials has been a crucial aspect for next‐generation lithium ion batteries (LIBs). A conventional nanoarchitecturing strategy is suggested to improve the rate performance of materials but inevitably brings about compromise in volumetric energy density, cost, safety, and so on. Here, micro‐size Nb 14 W 3 O 44 is synthesized as a durable high‐rate anode material based on a facile and scalable solution combustion method. Aberration‐corrected scanning transmission electron microscopy reveals the existence of open and interconnected tunnels in the highly crystalline Nb 14 W 3 O 44 , which ensures facile Li + diffusion even within micro‐size particles. In situ high‐energy synchrotron XRD and XANES combined with Raman spectroscopy and computational simulations clearly reveal a single‐phase solid‐solution reaction with reversible cationic redox process occurring in the NWO framework due to the low‐barrier Li + intercalation. Therefore, the micro‐size Nb 14 W 3 O 44 exhibits durable and ultrahigh rate capability, i.e., ≈130 mAh g −1 at 10 C, after 4000 cycles. Most importantly, the micro‐size Nb 14 W 3 O 44 anode proves its highest practical applicability by the fabrication of a full cell incorporating with a high‐safety LiFePO 4 cathode. Such a battery shows a long calendar life of over 1000 cycles and an enhanced thermal stability, which is superior than the current commercial anodes such as Li 4 Ti 5 O 12 .