Enabling Ultralow‐Temperature (−70 °C) Lithium‐Ion Batteries: Advanced Electrolytes Utilizing Weak‐Solvation and Low‐Viscosity Nitrile Cosolvent
Laibing Luo, Kean Chen, Hui Chen, Hui Li, Ruoyu Cao, Xiangming Feng, Weihua Chen, Yongjin Fang, Yuliang Cao
Abstract
Abstract Low‐temperature performance of lithium‐ion batteries (LIBs) has always posed a significant challenge, limiting their wide application in cold environments. In this work, the high‐performance LIBs working under ultralow‐temperature conditions, which is achieved by employing the weak‐solvation and low‐viscosity isobutyronitrile as a cosolvent to tame the affinity between solvents and lithium ions, is reported. The as‐prepared electrolytes exhibit a sufficiently high conductivity (1.152 mS cm −1 ) at −70 °C. The electrolytes enable LiCoO 2 cathode and graphite anode to achieve high Coulombic efficiency of >99.9% during long‐term cycling at room temperature, and to respectively achieve 75.8% and 100.0% of their room‐temperature capacities at −40 °C. Even the LiCoO 2 //graphite pouch cells can retain 68.7% of the room‐temperature capacity when discharged at −70 °C, and present stable cycling performance at −40 and 60 °C. This work provides a solution for the development of advanced electrolytes to enable LIBs working at wide‐temperatures range.