Study of the surface reaction mechanism of Li4Ti5O12 anode for lithium-ion cells

The formation of solid-electrolyte interface (SEI) film on the surface of LTO electrode at 25 and 55 A degrees C has been investigated. It is found that the SEI film, which is mainly composed of Li2CO3, LiF, and ROCO2Li, can be formed on the surface of LTO electrode. The differences of SEI film under 25 and 55 A degrees C are further discussed. The results reveal that the temperature has an effect on the morphology of formed SEI film. With the temperature increasing, the decomposition of carbonate species makes the SEI film became thicker and uneven, and also produces C2H4, which is attributed to the swelling of LTO cells at 55 A degrees C. When adding 0.5 wt.% succinonitrile (SN, CN-[CH2](2)-CN) in the electrolyte, the gassing behavior of the LTO cells at 3 C rate at 55 A degrees C can be obviously suppressed and the cyclic performance of the cells also improved.