Vanadium-substituted formation of anatase (V, Ti)O₂: Enhanced electrochemical performance for lithium ion batteries

TiO₂ has been used as a commercial anode material in lithium ion batteries (LIBs) owing to security and outstanding cycle stability. However, the lower specific capacity has limited its application. In this work, nanocrystalline anatase (V_0.47, Ti_0.53)O₂ is prepared via a hydrothermal process. When evaluated as an anode material for LIBs, nanocrystalline (V, Ti)O₂ exhibits enhanced specific capacity, high rate performance, and excellent cyclic stability. The specific capacity of the (V, Ti)O₂ anode reaches 370 mAh g^-1 in the first cycle, about 2.2 times the theoretical capacity of anatase TiO₂, and it retains a value of 320 mAh g^-1 after 500 cycles at a current density of 168 mA g^-1. At a current density of 1680 mA g^-1 (10 C), a specific capacity of as high as 137 mAh g^-1 is achieved after 1000 cycles. The high capacity is ascribed to the incorporated vanadium element, which undergoes the redox reactions of V⁴⁺ → V³⁺ → V²⁺ during the lithium storage process according to the ex-situ XPS results. The increased conductivity and surface pseudocapacitive contribution of the (V, Ti)O₂ anode as evidenced by the EIS and rate-changing CV investigation account for the improved rate performance with respect to TiO₂. This work demonstrates that (V, Ti)O₂ nanoparticles are a promising candidate for LIB anode materials.