Li-Salt Concentration Effects on Quick-Charge Performances of Spinel Lithium Titanium Oxide Negative Electrodes for Lithium-Ion Batteries

Abstract

The effect of Li-salt concentration in an electrolyte on the quick-charge performance of spinel lithium titanium oxide (LTO) is evaluated and analyzed. At a low C-rate application, the lithiation polarization of LTO decreases with the low Li-salt concentration because the Li diffusion coefficient increases at low Li-ion concentrations compared with those of concentrated electrolytes. Hence, a moderately Li-ion dissolved electrolyte is suitable for low-power applications as it enhances the energy efficiency of batteries. Whereas the low C-rate cycle efficiency is improved when using moderately Li-ion dissolved electrolytes, the electrochemical performances at a high C-rate application deteriorate owing to the abrupt depletion of Li ions near the surface of LTO. The voltage efficiency at a low C-rate application improves when a moderately Li-ion dissolved electrolyte is used, but the salt concentration significantly affects the high C-rate kinetics because Li ions from the electrolyte are supplied continuously for facile charges. Hence, the Li salt in the electrolyte for lithium-ion batteries should be designed to achieve high power performances and energy efficiency in batteries.