High‐Performance Polyimide Nanofiber Membrane for Progressive and Safe Lithium‐Ion Batteries Guarded by a Zirconia Armor Layer

Superior separator: A flexible zirconia nanoshell@polyimide (ZrO2@PI) composite separator with a core-shell structure is prepared via an in situ absorption complexation and hydrolysis strategy for high-performance and safe lithium-ion batteries. This separator combines the advantages of the PI nanofiber and the ceramic ZrO2, exhibiting excellent flame retardance, wettability, and thermal stability, far better than commercial Celgard-2400 separator. Batteries assembled with this ZrO2@PI composite separator display a higher rate capability and capacity retention rate.