Kozlova Anna, Uvarov Nikolai, Ulihin Artem
Institute of Solid State Chemistry and Mechanochemistry, SB RAS, Kutateladze Str. 18, 630128 Novosibirsk, Russia.
Mechanical Engineering Department, Novosibirsk State Technical University, 630071 Novosibrsk, Russia.
Materials (Basel). 2022 Sep 1;15(17):6079. doi: 10.3390/ma15176079.
The study demonstrates that the introduction of the electrochemically inactive dielectric additive LiTiO to LTO results in a strong decrease in the grain boundary resistance of LTO-LiTiO (LTC) composites at a low concentration of LiTiO. With the increase in the concentration of LiTiO in LTC composites, the grain boundary resistance goes through a minimum and increases again due to the growth of the insulation layer of small LiTiO particles around LTO grains. For LTO-TiO (LTT) composites, a similar effect was observed, albeit not as strong. It was found that LTC composites at low concentration of LiTiO 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 LiTiO in the vicinity of the interfaces between LTO and LiTiO. 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 TiO preventing the formation of coherent interfaces.
该研究表明，在低浓度LiTiO情况下，向LTO中引入电化学惰性的介电添加剂LiTiO会导致LTO-LiTiO（LTC）复合材料的晶界电阻大幅降低。随着LTC复合材料中LiTiO浓度的增加，晶界电阻先经历一个最小值，然后由于LTO晶粒周围小LiTiO颗粒绝缘层的生长而再次增加。对于LTO-TiO（LTT）复合材料，也观察到了类似的效果，尽管没有那么明显。研究发现，低浓度LiTiO的LTC复合材料具有异常高的充放电容量，超过了纯LTO的理论值。这种效应可能是由LTO和LiTiO之间界面附近LiTiO的电化学活性引起的。容量的增加可以用两相复合材料模型进行定性描述，该模型中存在具有高容量的界面层。与LTC复合材料不同，在LTT复合材料中未观察到容量增强，这可能是由于LTO和TiO晶体结构的显著差异阻碍了相干界面的形成。
