Electrolyte chemistry towards ultra-high voltage (4.7 V) and ultra-wide temperature (−30 to 70 °C) LiCoO2 batteries

Abstract

LiCoO2 batteries for 3C electronics demand high charging voltage and wide operating temperature range, which are virtually impossible for existing electrolytes due to aggravated interfacial parasitic reactions and sluggish kinetics. Herein, we report an electrolyte design strategy based on a partially fluorinated ester solvent (i.e., DFEA) that achieves a balance between weak Li+–solvent interactions, sufficient salt dissociation, high interfacial stability, and superior thermal stability to address the aforementioned challenges. The resulting high-voltage wide-temperature electrolyte (HWE) not only possesses low desolvation energy, fast Li+ transport, high oxidation stability, excellent thermal-abuse tolerance and non-flammability, but also enables the formation of both inorganic-rich cathode electrolyte interphase (CEI) and solid electrolyte interphase (SEI). Owing to the above merits, this HWE endows the highly stable operation of LiCoO2 cathodes under an ultra-high voltage of 4.7 V and Graphite||LiCoO2 batteries in an ultra-wide temperature range of −30 to 70 °C. Meanwhile, a 1.7 Ah-level 4.6 V Graphite||LiCoO2 pouch cell with a high energy density of 240 Wh kg−1 also delivers excellent cycling stability, representing a significant advancement in the design of electrolytes towards ultra-high voltage and ultra-wide temperature batteries.