LAUSR

Abstract Herein, a new and practical tri-layer separator with superb strength, good wettability, fire resistance, and shutdown function is fabricated via in-situ welding technique, using polybenzimidazole-sheath@polyimide-core nanofibers mat as the structural support and melt-processable polyether imide nonwoven as the interlayer. The in-situ welding technique has integrated the comprehensive functions of different materials including the polyimide, polybenzimidazole and polyether imide, endowing the tri-layer separator with superb strength of 46.5 MPa, outstanding thermal stability, and satisfying wettability to the electrolyte. Specifically, the in-situ welding technique is a simple and controllable approach to fabricate the tri-layer separator and has tremendous potential for low-cost industrial production. More significantly, the double insurances of outstanding fire resistance and higher shutdown temperature at approximately 235 °C can ensure the high safety and high temperature applications of battery. Notably, the lithium ion battery assembled with the as-prepared tri-layer separator shows much higher capability (132.4 mAh g−1, 5 C) than that with Celgard separator (95.3 mAh g−1, 5 C) and can keep good cycling stability at 120 °C, facilitating advances in battery safety and performances beyond the conventional separators. Thus, the present work makes a significant contribution for preparing multifunctional nonwoven separators, pointing to an interesting direction for high-performance and high-safety LIBs.