Application of Crosslinked Epoxy‐Based Gel Polymer Electrolytes for Li‐Ion Battery

ABSTRACT Polymer electrolyte‐based lithium‐ion batteries have garnered a lot of interest because of their potential to improve flexibility and safety. However, the economic and environmental sustainability of these electrolytes remains a critical factor in material selection. To address these concerns, polymer electrolytes derived from natural materials such as soybean oil have been explored for their affordability, abundance, environmental compatibility, and the presence of electron‐donating functional groups. Additionally, interfacial instability between the electrolyte and electrodes is one of the major challenges limiting the performance of lithium‐ion batteries. So, epoxidized soybean oil (ESO), as a bio‐based polymer, provides good film‐forming ability, mechanical flexibility, and compatibility with lithium salts, characteristics that are suitable for application in polymer electrolytes. In this work, crosslinked gel polymer electrolytes are prepared using ESO and bisphenol A diglycidyl ether (DGBEA), with citric acid serving as the crosslinking agent. The resulting polymer electrolytes exhibited a wide electrochemical stability window (up to 4.2 V), ionic conductivity in the range of 10 −4 S cm −1 , and a cation transference number between 0.47 and 0.76, demonstrating its potential for improving the electrochemical performance and stability of lithium‐ion batteries.