Characterization of N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide-based polymer electrolytes for high safety lithium batteries

摘要

Poly(vinylidene difluoride-co-hexafluoropropylene) (PVdF-HFP) membrane was prepared by electro-spinning. The membranes served as host matrices for the preparation of ionic liquid-based polymer electrolytes (ILPEs) by activation with non-volatile, highly thermally stable, and safe room temperature ionic liquid (RT1L) electrolytes; N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide (PynTFSI) complexed with 1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). In this work, the first combination of electrospun PVdF-HFP fiber polymer host and pyrrolidinium-based ionic electrolyte was employed for highly stable lithium batteries. The ILPE exhibited low Li~+-TFSI coordination, low crys-tallinity, high thermal stability, high electrochemical stability, and high ionic conductivity with a maximum of 1.1 × 10~(-4) S cm~(-1) at 0 ℃. The ILPE exhibited good compatibility with a LiFePO_4 electrode on storage and good charge-discharge performance in Li/ILPE/LiFePO_4 cells at room temperature, delivering specific capacities of 143 and 115 mA h g~(-1) at 0.1 and 1 C-rates. The ILPE also exhibited stable cycle properties and have therefore been demonstrated to be suitable for lithium battery applications.