Flame-retardant polyimide-based quasi-solid polymer electrolyte enabling high-performance and safe lithium-ion batteries

Quasi-solid polymer electrolytes (QPEs) represent one of the most promising materials for replacing flammable liquid electrolytes in lithium-ion batteries (LIBs) to enhance safety. However, the key to their further industrialization lies in developing QPEs that simultaneously possess both superior safety characteristics and excellent electrochemical performance. To address this, this work developed a flame-retardant and electrochemically high-performance Poly (vinylidene fluoride- co -hexafluoropropylene) -Polyimide (PFP-PI) QPE. This electrolyte exhibits an ionic conductivity of up to 1.02 × 10 −3  S/cm at room temperature. Batteries assembled with this electrolyte demonstrate stable cycling performance, retaining 88.49% of their capacity after 900 cycles at a 1 C current density. The electrolyte also exhibits robust mechanical properties and effectively suppresses lithium dendrite growth. Furthermore, without incorporating additional flame retardants, it significantly reduces smoke emission during thermal events while maintaining its electrochemical performance, thereby lowering the hazard risk. Flexible pouch cells assembled using this electrolyte maintain electrical integrity upon bending and cutting, showcasing high safety performance.