Lithiation-induced crystal restructuring of hydrothermally prepared Sn/TiO2 nanocrystallite with substantially enhanced capacity and cycling performance for lithium-ion battery

Abstract

A Sn-doped TiO₂ nanocrystallite with the composition of Sn_0.1Ti_0.9O₂ was prepared by hydrothermal co-precipitation followed by thermal annealing at 600 °C for 2 hours. Results combining high-resolution transmission electron microscopy, in situ XRD, ex situ XAS, and electrochemical impedance spectroscopy indicate that Sn_0.1Ti_0.9O₂ underwent restructuring to give Sn-substituted TiO₂ (Sn to Ti sites) by a lithiation reaction at 0.1C in a lithium-ion battery. The capacity and cyclability of Sn_0.1Ti_0.9O₂ were increased by ∼73% (to ∼598 mA h g⁻¹) and ∼17.4% compared with those of TiO₂ (∼345 mA h g⁻¹ and ∼22%) at 0.1C until the 250^th cycle. Our results proved that these improvements were caused by the self-aligned formation of Sn–Ti oxide and the subsequent formation of a SnLi_x local alloy at Ti sites.