Imidazolium-based room-temperature ionic liquid for lithium secondary batteries: Relationships between lithium salt concentration and battery performance characteristics

Relationships between the lithium salt concentration in a low-volatility solvent (room-temperature ionic liquid) and lithium secondary battery performance characteristics were investigated by using [LMOpositive electrode |DMPIm-TFSA+LiTFSA binary electrolyte | lithiummetal negative electrode] cells. Charge/discharge cycle and rate performance characteristics and various changes in resistance (lithium salt concentration and cycle number dependences) were examined, and the necessity of a suitable lithium salt concentration (0.32-0.64 mol kg?1) for good capacity retention and rate capability was concluded.