Transport and Electrochemical Properties of Li4Ti5O12-Li2TiO3 and Li4Ti5O12-TiO2 Composites

Abstract

The study demonstrates that the introduction of the electrochemically inactive dielectric additive Li2TiO3 to LTO results in a strong decrease in the grain boundary resistance of LTO-Li2TiO3 (LTC) composites at a low concentration of Li2TiO3. With the increase in the concentration of Li2TiO3 in LTC composites, the grain boundary resistance goes through a minimum and increases again due to the growth of the insulation layer of small Li2TiO3 particles around LTO grains. For LTO-TiO2 (LTT) composites, a similar effect was observed, albeit not as strong. It was found that LTC composites at low concentration of Li2TiO3 have unusually high charge–discharge capacity exceeding the theoretical value for pure LTO. This effect is likely to be caused by the occurrence of the electrochemical activity of Li2TiO3 in the vicinity of the interfaces between LTO and Li2TiO3. The increase in the capacity may be qualitatively described in terms of the model of two-phase composite in which there is the interface layer with a high capacity. Contrasting with LTC composites, in LTT composites, no capacity enhancement was observed, which was likely due to a noticeable difference in crystal structures of LTO and TiO2 preventing the formation of coherent interfaces.

Enhanced stability and the lithium storage mechanism of oxygen vacancy-induced heterogeneous Li4Ti5O12/TiO2(B) anolytes

“…10 Concurrently, considering that LTO can provide superior safety, extend durability as well as substantial power generation, it holds a minor but nonnegligible segment of the market share in lithium-ion batteries. 11 However, LTO is characterized by its low electronic conductivity, large band gap, and relatively low theoretical capacity resulting in reduced energy density, which thereby restrict its widespread application. 12 Constructing a heterogeneous structure, consisting of components with varied band gaps, has recently emerged as a promising strategy to enhance the electrochemical properties of anode materials.…”