PEU-based gel polymer electrolytes for lithium-ion batteries

Cross-linked gel polymer electrolytes based on PEU were prepared from the reaction of the hyper-branched polyether (PHEMO) with 4, 4'-diphenylmethane dissocyanate (MDI) in electrolyte. The structures, thermal stabilities and ionic conductivities of the as-prepared polymer electrolytes were investigated by fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and alternating current (AC) impedance. It shows that the polymer electrolyte PM-1M-Z4 can achieve an ionic conductivity of 2.53 × 10^-3S/cm at room temperature. Cyclic voltammogram indicates that the electrochemical stability window is from 2.3-4.0V. The polymer electrolytes have good thermal and mechanical stability. In addition, small molecules of electrolytes were perfectly enclosed by polymer chains, which can avoid leaking liquid. Therefore, it is benefit for the safety of lithium-ion batteries.