Observation of the structural changes of sol-gel formed Li2MnTi3O8 during electrochemical reaction by in-situ and ex-situ studies

In this work, spinel Li2MnTi3O8 is successfully prepared by using a simple sol-gel route and evaluated as an anode material for lithium-ion batteries. Charge-discharge tests exhibits than spinel Li2MnTi3O8 can deliver an initial discharge capacity of 273.5 mAh g−1 and the reversible capacity is kept at 206.1 mAh g−1 after 50 cycles, corresponding to 94.5% of the initial charge capacity. The electrochemical reaction mechanism between Li2MnTi3O8 and lithium is investigated based on the results of various in-situ and ex-situ observations. The result indicates that the (Li0.505Mn0.495)tet(Li0.495Mn0.005)octTi1.5octO4 has multiple interstitials to accommodate lithium ions during the lithiation process, in which the octahedral sites (4a) would be occupied by lithium ions at high working potential and the tetrahedral sites (8c) would be occupied by lithium ions at low working potential. As a result, two two-phase transitions between three end-number phases Li2MnTi3O8, Li3MnTi3O8 and Li5MnTi3O8 can be observed during the reversible electrochemical reaction between Li2MnTi3O8 and lithium.