Preparation and performance study of ionic liquid @ boron nitride modified polyimide proton exchange membrane

Abstract Proton exchange membrane (PEM) plays a relatively significant part in PEM fuel cells (PEMFCs). In this study, ionic liquid were grafted onto boron nitride (ILs@BN) were prepared by wet ball milling, and the polyimide (PI) composite films with different contents (1, 2, 3, 4, and 5 wt%) of ILs@BN were fabricated by solution‐casting method. Results showed that compared with the original polyimide films, the performance of the obtained composite films has been significantly improved. Tensile strength of film containing 4 wt% ILs@BN was enormously enhanced by 93.62% (from 47 to 91.8 MPa), respectively, in contrast to pure PI film. Compared with pure PI film, film containing with 4 wt% ILs@BN was reduced from 71.2° to 63.2°, which indicated the better hydrophilicity of the film and potential proton transport channels. The composite film exhibited excellent proton conductivity, which was tremendously elevated by 58.35% (from 0.1215 S cm −1 for pure PI to 0.1924 S cm −1 for film containing with 4 wt% ILs@BN). Comprehensively, the film containing with 4 wt% ILs@BN presenting excellent mechanical properties (91.8 MPa), contact angle (63.2°) and proton conductivity (0.1924 S cm −1 ) demonstrating strong potential applications in fuel cells.