In situ cross-linked fluorinated gel polymer electrolyte based on PEGDA-enabled lithium-ion batteries with a wide temperature operating range

Abstract

Lithium-ion batteries (LIBs) require a wide operating temperature window to meet their actual demand. Herein, a fluorinated gel polymer electrolyte (F-GPE) was synthesised by in situ thermal polymerisation method using poly (ethylene glycol) diacrylate (PEGDA) as a cross-linking agent. The F-GPE showed excellent electrochemical stability in a wide voltage window in the range of 2–5.6 V, high ionic conductivity (above 1.2 mS cm−1 at –40 °C), superior lithium-ion transfer number (tLi+) of 0.51 at room temperature, and good compatibility with lithium metal. Additionally, the LiCoO2||F-GPE||graphite pouch battery, which the surface density of LiCoO2 was 30 mg cm−2, showed an outstanding discharge capacity in a wide temperature from –40 to 60 °C. The results displayed the retention rate of discharge capacities at –40 and 60 °C were 64.9% and 106.3% of that at room temperature, respectively. F-GPE retained the low-temperature performance of the electrolyte and improved the stability and electrochemical behavior at high temperature, providing a new strategy for the large-scale application of LIBs in a wide operating temperature.