A lithium ion battery separator with a dual functional coating and a method of making the same

Abstract

The application discloses a lithium ion battery diaphragm with a bifunctional coating and a preparation method thereof, and belongs to the technical field of lithium ion battery diaphragms. The diaphragm is coated with a bifunctional composite coating composed of PSSLi and PFPE on the surface of a PE base film opposite to the negative electrode. The PSSLi serves as a single ion conductor, and the strong electrostatic field generated by the fixed sulfonate anions of the PSSLi effectively promotes the desolvation process of lithium ions and reduces the interface reaction energy barrier. The PFPE is preferentially reduced and decomposed on the surface of the negative electrode to in-situ construct a stable solid electrolyte interface layer rich in lithium fluoride. The synergistic effect of the two achieves the rapid transmission and uniform deposition of lithium ions, and fundamentally inhibits the growth of lithium dendrites. The composite coating diaphragm prepared by the application can significantly improve the ion migration number, critical current density, cycle life and coulombic efficiency of the lithium metal battery, has excellent rate performance and interface stability, and has a simple preparation process and is suitable for large-scale production.

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