Siloxy-Functionalized Gel Polymer Electrolyte for High-Temperature Stable Lithium-Ion Batteries

The rapid transition toward electric vehicles and large-scale energy storage systems has intensified the demand for lithium-ion batteries (LIBs) capable of reliable operation under harsh temperature conditions. However, conventional liquid electrolytes suffer from severe degradation at elevated temperatures. Herein, we report a multifunctional gel polymer electrolyte (GPE) employing a siloxy-functionalized cross-linker, siloxy-pentaerythritol triacrylate (SiO-PETA), to enhance the high-temperature cycling stability and safety of LIBs. The trimethylsilane groups in SiO-PETA effectively scavenge corrosive HF, thereby mitigating cell degradation associated with transition metal dissolution. In addition, the chemically cross-linked polymer matrix encapsulates the liquid components in the GPE, suppressing parasitic side reactions and reducing electrolyte vaporization at elevated temperatures. A graphite/LiNi_0.6Co_0.2Mn_0.2O₂ pouch-type cell employing the GPE exhibits superior capacity retention at 70 °C, markedly outperforming a conventional liquid-electrolyte cell. Furthermore, the GPE provides enhanced safety, as evidenced by stable open-circuit voltage at 150 °C and reduced flammability. These results demonstrate that the SiO-PETA-based GPE effectively suppresses electrolyte and electrode degradation, enabling stable LIB operation at high temperatures.