Spontaneous Li-Ion Transfer from Spinel Li4Ti5O12 Surfaces: Deterioration at Li4Ti5O12/Electrolyte Interfaces Stored at Room Temperature

Spinel lithium titanium oxide (LTO; Li4Ti5O12) is one of attractive negative electrode materials for, high-performance lithium-ion batteries. We studied the changes of LTO-electrode surfaces in contact with liquid electrolytes without electrochemical operation, as the basic state of a stored cell. The electrochemical properties of the LTO-crystal electrode were greatly deteriorated after soaking in a liquid electrolyte (1 M LiPF6 in PC) for 2 weeks at room temperature. Spinel LTO structure was changed into rock-salt like structure at the surface region. The chemical compositions of Li and O were decreased at the 'surface region, suggesting spontaneous Li+ and O2- transfer from the LTO surface. The present structural and chemical changes of the surface region was explained as disoidered-spinel phase generation with less Li-ion conductivity. (C) The Author(s) 2015. Published by ECS. All rights reserved.