Heterogeneous Interface Design with Oxygen Vacancy-Rich Assistance High-Capacity Titanium-Based Oxide Anode Materials for Sodium-Ion Batteries

Researchers are paying more attention to sodium-ion batteries (SIBs) because of their abundant supply of sodium resources and affordable price. TiO₂ offers excellent safety and a long lifespan as an anode material for SIBs. However, the process kinetics is slow due to its limited Na⁺ storage efficiency, weak conductivity, and irreversible Na⁺ capture. In order to address these issues, this review uses a mix of the template approach and the double-hydrolysis method to manage the structure and diffusion of TiO₂-based anode materials by synthesizing FeTiO₃/TiO₂ heterostructured double-shell microspheres (FTO). Through the built-in electric field effect caused by their heterostructures, FTO materials improve reaction kinetics, boost electronic conductivity, and lower the diffusion energy barrier of Na⁺. Their distinctive double-shell structure can increase electrolyte infiltration, shorten the diffusion distance between ions and electrons, and accommodate volume expansion during cycling. Furthermore, the irreversible capture of Na⁺ and the unfavorable interactions between the surface active site and electrolyte can be successfully inhibited by FTO heterostructures. FTO has an exceptionally high capacity (reaching 362.7 mA h g^-1 after 60 cycles at 20 mA g^-1) and excellent cycle stability (with a decay rate of 0.0061% after 1000 cycles at 2 A g^-1). The strategy of constructing heterogeneous interfaces assists with high-performance SIB anode design.