The electro-chemical properties and intercalation mechanism of low strain Li2TiO3 as a high-performance anode material for lithium-ion batteries

In this article, the sol-gel synthesized β-Li2TiO3, referred to as sg-β-Li2TiO3, exhibits superior electro-chemical performance, compared with the theoretical specific capacities of frequently investigated Titanium based oxides, for example, LiTiO2 (143 mAh g-1), Li4Ti5O12 (175 mAh g-1) and Li2Ti3O7 (198 mAh g-1). It delivers a considerable specific capacity of more than 200 mAh g-1 within 100 cycles and close to 200 mAh g-1 after 200 cycles and preserves coulombic efficiency above 97% for all the cycles. After more than 500 cycles, the reversible specific capacity of sg-β-Li2TiO3 is more than 170 mAh g-1 and a less than 2% capacity degeneration is observed for the followed several hundreds of cycles. DFT calculations and MD simulations show 8 f void mediated diffusion comprise the two dimensional diffusion layer on a-b plane and the neighboring diffusion layers are interconnected by two 8 f voids via a Li2 atom. Low energy barriers and high Li+ activities are observed. Three intermediate phases, corresponding to intercalation level x = 0.5, 0.75 and 0.875 in β-Li2+xTiO3, are identified for the intercalation process with the maximal intercalation level 0.875. Both ex-situ XRD and theoretical calculations reveal low volume change or strain less than 5% in the intercalation process. Also, an insulator-metal transition upon lithiation is observed by the electronic structure analysis. A full view of the connectivity of Li sites and the demonstration of the diffusion mechanism and the energy barrier on MEPs [Display omitted] •Carbon free anode material Li2TiO3 for LIBs is fully evaluated.•The Li+ migration panorama is fully revealed by DFT and MD.•Li+ transportation kinetics reveals the features of fast ion conductor.•An insulator-metal transition is observed upon the intercalation of Li+.•Li+ intercalation/deintercalation mechanism and phase evolution are determined.