Reducing Crystallinity of Micrometer-Sized Titanium–Niobium Oxide through Cation Substitution for High-Rate Lithium Storage
Zichen Wu, Min Guo, Yuantao Yan, Huanglin Dou, Wanyu Zhao, Yijie Zhang, Shiying Li, Jianwei Wu, Xihan Bin, Xiaoli Zhao, Xiaowei Yang, Dianbo Ruan
Abstract
As promising anode materials for lithium-ion batteries, titanium–niobium oxides still suffer from the bottleneck of ion transport, which severely limits their practical usage. In this work, the ion-transport kinetics of micrometer-sized Ti2Nb10O29 is improved by crystallinity mediation. The crystallinity of Ti2Nb10O29 is intrinsically reduced through cation substitution (Nb5+ → Ti4+ and W6+), with Ti2.5Nb9W0.5O29 obtained. The amorphous phases not only optimize the ion transport through isotropic ion diffusion path but also introduce more oxygen vacancies, which can serve as nucleation sites for phase changing and improve electron conductivity. As a result, Ti2.5Nb9W0.5O29 exhibits superior kinetics and remarkable rate performance. Even with large particle sizes from 5 to 20 μm, Ti2.5Nb9W0.5O29 can achieve a reversible specific capacity of 110 mAh g–1 at a high current density of 10 A g–1, much higher than Ti2Nb10O29 (11.1 mAh g–1). This work provides a novel view for the development of practical, high-performance anode materials for LIBs.