Highly exposed TiO2 (001)/MXene heterostructure with ultrafast kinetics for high-performance sodium storages

Anatase titanium dioxide (TiO 2 ) has garnered significant attention as an anode material for sodium-ion batteries (SIBs) due to its high crystallinity and two-dimensional (2D) diffusion pathways. However, its semiconducting nature results in poor electrical conductivity and sluggish Na⁺ diffusion kinetics. To address these limitations, we propose a novel strategy that integrates the highly exposed TiO 2 (001) facet with Ti 3 C 2 T x MXenes, resulting in the formation of a heterostructure denoted as ((001)T-MX). This heterostructure leverages the strengths of both components to mitigate the shortcomings of TiO 2 alone. The highly exposed TiO 2 (001) facet exhibits a lower Na⁺ insertion energy barrier compared to the TiO 2 (101) facet, thereby facilitating enhanced Na⁺ diffusion along the (001) direction. The incorporation of MXenes not only reduces the band gap energy but also significantly improves the electron conductivity, addressing the inherent conductivity issues of TiO 2 . As an SIB anode, the (001)T-MX delivers a high specific capacity of 121.3 mAh g −1 at 0.5 A g −1 after 500 cycles and exhibits superior cycling stability with a specific capacity of 99.1 mAh g −1 after 1000 cycles at 1.0 A g −1 . This work provides a robust framework for developing advanced heterostructures with tailored crystal faces, paving the way for enhanced energy storage solutions.