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

Published on Advanced Materials (19 February 2020)
Co-author: Dr Qi Liu, Assistant Professor, Department of Physics

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 Nb14W3O44 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 Nb14W3O44, 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 Nb14W3O44 exhibits durable and ultrahigh rate capability, i.e., ≈130 mAh g−1 at 10 C, after 4000 cycles. Most importantly, the micro‐size Nb14W3O44 anode proves its highest practical applicability by the fabrication of a full cell incorporating with a high‐safety LiFePO4 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 Li4Ti5O12.

Read more: https://onlinelibrary.wiley.com/doi/full/10.1002/adma.201905295