Surface-dominated sodium storage enabled by TiO2 nanosheets with 84 % exposure of (0 0 1) facets for high-performance Na-ion battery anodes

Abstract

Anatase titanium dioxide (TiO₂) has garnered enormous attention as a promising anode material for sodium-ion batteries (SIBs), owing to its non-toxicity, superior structural stability, and cost-effectiveness. Nevertheless, its intrinsic low electrical conductivity poses a substantial challenge to its practical applications. Here, the ultrathin TiO₂ nanosheets were obtained. The TiO₂ nanosheets with a thickness of ∼8 nm and exposed 84 % (0 0 1) facet. The exposed (0 0 1) crystal facets and ultrathin nanosheet structure provide abundant active sites for Na-ion adsorption, shortens ion diffusion pathways, enhances reaction kinetics, and significantly boosts the pseudocapacitive effect. This synergistic strategy of exposed (0 0 1) facet with nanosheets structure leads to an exceptional capacity of 177.1 mAh/g at 0.1 A/g, and 59 % capacity retention at 5 A/g. This work will contribute to the understanding of facet-dependent electrochemical behavior anode materials for high-performance SIBs.