Ultrahigh-strength, nonflammable and high-wettability separators based on novel polyimide-core@polybenzimidazole-sheath nanofibers for advanced and safe lithium-ion batteries

Abstract

Herein, a novel core@sheath nanofibrous membrane with ultrahigh strength, superior fire resistance and high wettability is prepared for lithium-ion batteries separator via self-bonding and self-compression technique, using the polyimide nanofiber as the core material and polybenzimidazole as the reinforced sheath material. The self-bonding and self-compression make the polyimide@polybenzimidazole-reinforced nanofibrous membrane possess ultrahigh strength up to 59 MPa and more compact porous structure, which is an exciting finding. The as-synthesized nanofibrous membrane exhibits super high thermal dimensional stability up to 300 °C and satisfying wettability. Furthermore the good thermal stability of as-synthesized membrane enables it to preserve the integrity of backbone at temperatures as high as 540 °C. More significantly, the unique fire resistance of polybenzimidazole also ensures the high security of batteries. Notably, the battery using the as-synthesized separator displays much higher capability (130.2 mAh g−1, 5 C) than that with Celgard separator (95.4 mAh g−1, 5 C), and it can work steadily at 120 °C. Therefore, we believe that this work is really a significant breakthrough for the polyimide nonwoven separators, especially the ultrahigh mechanical strength, indicating the promising applications for the next generation high-safety and high-performance lithium-ion batteries.