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

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• The growing demand for electric vehicles and energy storage necessitates lithium-ion batteries (LIBs) with improved high-temperature performance.
• Conventional liquid electrolytes in LIBs degrade significantly at elevated temperatures, limiting their operational range and safety.
• Developing advanced electrolytes is crucial for enabling reliable LIB function under harsh thermal conditions.

Purpose of the Study:

• To develop a multifunctional gel polymer electrolyte (GPE) that enhances the high-temperature cycling stability and safety of lithium-ion batteries.
• To investigate the role of a siloxy-functionalized cross-linker, SiO-PETA, in mitigating electrolyte and electrode degradation at elevated temperatures.
• To demonstrate the superior performance of the GPE in a practical LIB cell under demanding thermal conditions.

Main Methods:

• Synthesized a gel polymer electrolyte (GPE) incorporating a siloxy-functionalized cross-linker, siloxy-pentaerythritol triacrylate (SiO-PETA).
• Incorporated the GPE into graphite/LiNi_0.6Co_0.2Mn_0.2O₂ pouch-type lithium-ion battery cells.
• Evaluated the high-temperature cycling stability, safety characteristics (thermal stability, flammability), and degradation mechanisms of the GPE-based cells compared to conventional liquid-electrolyte cells.

Main Results:

• The SiO-PETA based GPE effectively scavenges corrosive HF, reducing transition metal dissolution and cell degradation.
• The cross-linked polymer matrix in the GPE suppresses parasitic reactions and electrolyte vaporization at high temperatures.
• GPE-based LIB cells demonstrated superior capacity retention at 70 °C and enhanced safety, including stable open-circuit voltage at 150 °C and reduced flammability.

Conclusions:

• The developed SiO-PETA based GPE significantly improves the high-temperature cycling stability and safety of lithium-ion batteries.
• This novel GPE effectively mitigates electrolyte and electrode degradation pathways that limit performance at elevated temperatures.
• The findings pave the way for developing more robust and reliable LIBs for demanding applications, including electric vehicles and grid storage.