Crystal structure regulation boosts the conductivity and redox chemistry of T-Nb2O5 anode material.

T-Nb 2 O 5 as a promising candidate anode has attracted great interest for ultrafast lithium-ion batteries (LIBs) due to its good ion conductivity and safety. However, the relatively inferior electric conductivity and low capacity greatly limit its commercial application. Herein, a trace Co doping strategy is reported to enhance the electric conductivity and redox chemistry of T-Nb 2 O 5. The original Nb sites are partially replaced by Co, which endows Co-Nb 2 O 5 with high electronic conductivity without affecting the crystalline host structure, meanwhile induces multielectron redoxes of Nb⁵⁺/Nb⁴⁺ and Nb⁴⁺/Nb³⁺ during lithium-ion insertion process. As a LIB anode, the resulting Co-Nb 2 O 5 nanoparticles display a high discharge capacity (256.1 mAh g⁻¹ at 0.1 A g⁻¹), superior rate capability (141.7 mAh g⁻¹ at 5 A g⁻¹) and good cycling stability (179.7 mAh g⁻¹ at 1 A g⁻¹ after 500 cycles). The ultrafast lithium storage and high-capacity electrochemical performance of Co-Nb 2 O 5 owing to its high electric conductivity and multielectron redox upon lithiation/delithiation. The selective transition metal doping strategy provides a new direction for the development of new insertion-type oxide anodes towards fast charging and high-capacity LIBs. [Display omitted] • For Co-Nb 2 O 5 nanoparticles, trace Co transition metal dopants partial occupy the Nb sites with low coordination. • Co-Nb 2 O 5 delivers high electronic conductivity , meanwhile maintains crystalline host structure, and exhibits ultrafast lithium storage. • Trace Co can induce multielectron redoxes of Nb⁵⁺/Nb⁴⁺ and Nb⁴⁺/Nb³⁺, resulting in higher specific capacity. • The introduction of metal dopants into insertion-type materials offers a new idea for fast-charging and high-capacity LIBs. [ABSTRACT FROM AUTHOR]