Designing innovative heterostructures composed of TiO2/Bi2Te3/carbon cloth for highly efficient sodium-ion batteries†

Abstract

Bi-based materials can retain massive amounts of sodium ions through alloying and conversion reactions, resulting in excellent theoretical capacity. However, during the sodiation/desodiation process, there is always a significant volume change in the alloying reaction. In this work, TiO₂-coated hexagonal-phase topological insulator (TI) Bi₂Te₃ composites grown on carbon cloth (CC) were prepared using a solvothermal reaction and an atomic layer deposition process (TiO₂/Bi₂Te₃/CC) as anode materials for sodium-ion batteries without the need for a binder. Compared to the pure Bi₂Te₃ electrode, the optimized TiO₂/Bi₂Te₃/CC composite exhibits a superior specific capacity of 450 mA h g⁻¹, a high rate performance of 0.1 A g⁻¹, and a high cycling stability of 100 cycles due to the inherent properties of TIs, contributed by the effective TiO₂ cladding layer and large interfacial spacing of Bi₂Te₃. The enhanced reversible capacitance, rate capability, and cycling performances can be attributed to the heterointerfaces and excellent mechanical properties of TiO₂, which balance the electronic structure of the building blocks and inhibit the detaching of Bi₂Te₃ due to large internal stresses. The amorphous TiO₂/Bi₂Te₃/CC composite was treated in a tubular furnace to obtain crystalline TiO₂/Bi₂Te₃/CC, and the electrochemical performance of the heterostructures formed by the TiO₂ coating layer with different properties was compared. This work demonstrates the enormous potential for enhancing the sodium-ion storage capabilities of alloy electrode materials by constructing heterostructures.