Bio-derived yellow porous TiO2: the lithiation induced activation of an oxygen-vacancy dominated TiO2 lattice evoking a large boost in lithium storage performance

Abstract

Oxygen deficient TiO₂ has attracted extensive attention owning to its narrow bandgap and high electrical conductivity. In this work, novel yellow TiO₂ with hierarchically porous architecture is fabricated by a facile pyrolysis method in air via a biomass template. The obtained yellow TiO₂ exhibits interesting lithiation induced activation during cycling, which gives rise to a phase change from poorly crystallized TiO₂ to an amorphous phase, accompanied by a colour change from yellow to black. In contrast to the intercalation mechanism reported in most of the literature on the TiO₂ anode of LIBs, notably, the reversible redox reaction between Ti³⁺ and metal Ti can be verified in this case, demonstrating the novel conversion reaction mechanism of the TiO₂ electrode. Based on this, the yellow porous TiO₂ delivers enhanced electrochemical performance as an anode for LIBs with a superior capacity of 480 mA h g⁻¹ at 5 A g⁻¹ and a high capacity of 206 mA h g⁻¹ at 10 A g⁻¹ after 8000 cycles.