Effective Strategy to Improve Safety of Lithium-Ion Batteries by Constructing Ion Transport Modes and Employing a Cross-Linking Structure in the Separator

For lithium-ion batteries, the design of the ion transport mode in the separator and outstanding mechanical strength are crucial for enhancing the application safety of batteries. In this study, a hybrid separator with multiple modes of lithium-ion transport is successfully prepared using a lithiated sulfonated covalent organic framework (SCOF@Li) and cross-linked poly(aryl ether benzimidazole). The obtained hybrid separator not only shows outstanding heat resistance but also exhibits a satisfactory inhibitory effect on the disordered growth of lithium dendrites. Specifically, it withstands temperatures up to 200 °C, and the Li/SCOF@Li@C/Li symmetric cell has a long-term cycling stability of up to 2400 h at a current density of 1 mA cm –2 . Notably, the mechanical strength of the hybrid separator is more than doubled by a cross-linking reaction. Moreover, the cell demonstrates high ionic conductivity (1.36 mS cm –1 ) and excellent rate performance owing to the multiple modes of lithium-ion transport in the hybrid separator.