Design and preparation of cross-linked polyimide binders with high bonding strength and high voltage tolerance for high performance lithium-ion batteries

Polymer binder plays an important role in the fabrication and performances of lithium-ion batteries (LIBs). Developing new binder materials that can meet the requirement of high voltage conditions and higher working temperatures has aroused increasing research interest. In this work, a novel cross-linked polyimide binder (PI-APE-AZ) with high adhesion, high voltage tolerance and high Li ions affinity was designed and synthesized. The peeling forces of the cathodes binding by cross-linked polyimide reached 0.531 N/mm, which was 10 times higher than the commercial PVDF of only 0.051 N/mm. The electrochemical performances of PI-APE-AZ constructed cathodes exhibited much superior performances that the commercial PVDF in terms of thermos stability, cycling performances and rate performances, especially under higher voltages conditions. More intriguing, the Li + transfer in the polyimide binding cathodes was greatly enhanced than the PVDF as indicated by the EIS and kinetics fitting results. This crosslinking strategy was verified by other polyimides constructed by different monomers, indicating the great potential of polyimide binders in LIBs.