In Situ Reinforcing: ZrO2-Armored Hybrid Polyimide Separators for Advanced and Safe Lithium-Ion Batteries

High-performance polymeric separators are crucial materials for advanced rechargeable lithium-ion batteries (LIBs). Generally, separators need simultaneously possess qualified flame retardancy, mechanical strength, wettability, and ion conductivity. Here, we report a series of zirconium dioxide (ZrO2)-armored polymeric separators to boost the comprehensive performance of a separator by in situ growing a ZrO2 nanolayer on polyimide (PI) nanofibers. The ZrO2 nanolayer can serve as a protective coating to reinforce the PI nanofibers membrane. The ZrO2-reinforced layer endows a hybrid membrane with the superior strength of 39.24 MPa, which is instructive for the development of functional hybrid nanofibers. Moreover, ZrO2-armored PI separators display preferable wettability, fire resistance, and low ion-transport resistance as compared to those of a Celgard-2400 separator. The flame retardance of a ZrO2-armored PI separator also enhances the security of LIB. Specifically, ZrO2-armored hybrid PI separators display superb battery capability (128.6 mAh g–1@5C) in comparison to polyolefin microporous membrane (95.2 mAh g–1@5C). Furthermore, the cell using the ZrO2-armored PI nanofiber membrane shows high cycling stability over 100 cycles at 1C. Thus, the present study provides a design thought for the preparation of advanced organic/inorganic hybrid separators for LIBs.