One-pot simple and highly thermally stable PI-film separators for Li-ion batteries

•ü Simple, one-pot hydrothermal method for PI-film separator synthesis.•ü The synthesized PI-film separator exhibits highly thermally and chemically stable.•The PI-film separator excellent stability in EC/DMC electrolyte. Separators play a vital role in the battery industry, particularly Li-ion battery separators, and should be thermally and chemically stable to prevent internal short circuits for safety and ionic conductivity. In this study, a polyimides-film separator (PI-FS) was synthesized using a simple one-pot method, and its thermal and chemical stabilities were studied. The results of this study were compared with those of Celgard 2400 and PP-PE-PP separators. The PI-FS exhibited superior thermal stability in the EC-DMC electrolyte than in the EC-DEC and other commercial separators.