Rate Performance of LiCoO<sub>2</sub> Half-cells Using Highly Concentrated Lithium Bis(fluorosulfonyl)amide Electrolytes and Their Relevance to Transport Properties

For the rapid charge-discharge performance of Li-ion batteries (LIBs), ionic conductivity (?) and Li ion transference number (t+) are important parameters electrolytes. Electrolytes with high t+ alleviate concentration polarization upon fast charge-discharge, prevent diffusion-limited mass transfer Li+ ions. Recent studies have suggested that certain highly concentrated electrolytes exhibit better rate performances than conventional organic despite their lower ?. However, relationship between transport properties (t+ ?) enhanced LIBs is yet to be elucidated. To evaluate in terms properties, we investigated discharge capability LiCoO2 (LCO) half-cells using lithium bis(fluorosulfonyl)amide (Li[FSA]) electrolyte ?-butyrolactone (GBL), acetonitrile (AN), dimethyl carbonate (DMC), 1,2-dimethoxyethane (DME) solvents. There was a remarkable solvent dependence t+, highest tLi+current 0.67 observed for GBL-based measured very-low-frequency impedance spectroscopy (VLF–IS) method. The LCO half-cell delivered higher capacities cells DMC- DME-based at current densities. improved attributable derived from tLi+current. We demonstrated importance on high-rate battery performance.