Study On Electrolyte For Appling To Wide Temperature Range Of Lithium Ion Battery

This paper aims at solving the working temperature (especially when temperature lower than–20℃) of Li–ion cell can not meet the applying requirements of spaceflight, aviation and portable electronic affairs. Being targeted for practicality, the working temperature of the Li–ion cells was widened from–20℃～55℃to–40℃～55℃by optimizing component solvent systems.Ternary & quarterrnary component solvent systems based on the mixed solvent of cyclic ethyl carbonate and several aliphatic alkyl carbonates and the conduction behaviors in the range of–40℃to 55℃of these electrolytes were also investigated. During the experiment, conductance of quarterrnary component solvent system composed of EC, EMC & DEC with 1.0 mol·L^–1 LiPF₆ was the best one at–40℃, however was not satisfied at 55℃. Ternary component solvent system of EC + DMC + EMC(1:1:1)with 1.0 mol·L^–1 LiPF₆ had the satisfied ion conductivity below–40℃and 55℃.During investigating the conduction behaviors of electrolytes composed of different concentration of the solute (LiPF₆) with same solvent system, the EC + DMC + EMC(1:1:1)with 1.0 mol·L^–1 LiPF₆ showed excellent conduction behavior in the range of–40℃to 55℃. The ICR1865 cells produced 3 batches continuously using the electrolytecomposed of EC + DMC + EMC(1:1:1)with 1.0 mol·L^–1 LiPF₆ could deliver 2060 mAh at room temperature,while energy density reached 178 Wh·kg^–1, and also showed excellent temperature performance: delivering respectively over 47% at–40℃and 100% at 55℃of the rated capacity Furthermore the cells proved outstanding cycle life: delivering respectively 93% at 100 and 80% at 500 of the rated capacity. At last, the cells passed safety and environment tests which met the requirements of practical arms.