Probing the Electrochemical Processes of Niobium Pentoxides (Nb2O5) for High‐Rate Lithium‐ion Batteries: A Review

Abstract The rising demand to electrify power‐intensive energy devices and systems, as well as fast charging, has imposed a great challenge in current chemistries for lithium‐ion batteries (LIBs), whose rate capabilities are predominantly restricted by the conventional graphite anode. Niobium pentoxide (Nb 2 O 5 ) is a promising high‐rate anode material for LIBs with extraordinary rate performance beyond 5 C and good theoretical capacity (~202 mAh ⋅ g −1 ). With many possible crystal structures, Nb 2 O 5 has a complicated family of different polymorphs, each of which can possess distinct electrochemical properties, specific capacity, cycling stability, and rate capability. This special feature of Nb 2 O 5 makes it a challenging material to understand and requires a comprehensive investigation of every one of its polymorphs. In this paper, we summarize the state‐of‐the‐art research on Nb 2 O 5 polymorphs for LIBs, with an emphasis on the advanced characterisation techniques that have been used to probe the electrochemical processes of Nb 2 O 5 . Key findings related to Nb 2 O 5 that have emerged from the previous studies are highlighted, and new scientific questions that are important for its scale‐up and commercialization are proposed for future research.