Interface engineering of quasi-solid poly(vinylidene fluoride) separators for next-generation lithium ion batteries

Interfaces and intermediate phases, which both promote energy storage in batteries and trigger many degradations, have been a double-edged sword in battery development. To boost battery performance, the interface associated with the separator, in particular the modulation of the heterogeneous components and the microenvironment of the interface, can be more effective. Very recently, the emerging poly (vinylidene fluoride) (PVDF) separator, due to the simple film formation process, chemical inertness, and high dielectric constant, etc., has a significant superiority in the modification of internal separator and interface with the electrodes. Researchers have made great progress in modifying the internal interface, cathode electrolyte interface (CEI), and anode electrolyte interface (AEI) of composite separators. Enhanced interfacial interaction strategies including the participation of components in interfacial reactions and the provision of interfacial ion transport channels, and construct high Young's modulus interface can simultaneously improve the thermal, mechanical, electrochemical stability, and ionic-electronic equilibrium. Then, this work discusses the research progress of the interface improvement strategies in detail, and further summarizes the characterization techniques of the interface problems, which will highlight the necessity of the research and development of the interfacial chemistry of the next generation PVDF separators, along with vital insights on the future development.