In-situ preparation of gel polymer electrolytes in a fully-assembled lithium ion battery through deeply-penetrating high-energy electron beam irradiation

Several in-situ preparation methods of gel polymer electrolytes (GPEs) to develop long-lasting and safe lithium ion batteries (LIBs) recently have been reported. However, the reported in-situ methods still have technical gaps for practical industrial uses in terms of processing time, integrity with the current production line, and scalability. Here, we report an in-situ method to prepare crosslinked poly(vinylene carbonate-co-cyanoethyl acrylate) (PVCEA) GPEs using 10 MeV electron beam (EB) irradiation in a fully-assembled metallic housing LIB that can be processed in a short time without any initiator or thermal treatment. The successful in-situ formation of PVCEA GPEs was achieved at absorbed doses above 16 kGy (irradiation time of 56 s), leading to intimately integrated GPEs with the electrodes, while ensuring stable charge and discharge performance. The prepared PVCEA GPE exhibited a higher transference number (tLi+ = ca. 0.53) and a wider electrochemical operation window (up to 5.0 V) than those of a liquid electrolyte (LE), while providing good ionic conductivity (1.17 mS/cm at 20 °C). Furthermore, the PVCEA GPE-based LIB prepared at an optimized dose of 16 kGy showed comparable retention capacity of 83 % at 0.5C to the conventional LE-based LIB after 300 cycles at 25 °C, and more importantly, better cycling durability at elevated temperature of 60 °C in comparison to the LE-based LIB. This study suggests that the combination of radiation-sensitive precursor formulation and high-energy EB with high penetration ability can provide a promising solution for industrial production of high-performing and safe LIBs.