Solid electrolyte based on waterborne polyurethane and poly(ethylene oxide) blend polymer for all-solid-state lithium ion batteries

A series of solid polymer electrolytes (SPEs) based on waterborne polyurethane (WPU), poly(ethylene oxide) (PEO) and lithium bis(trifluoromethane sulfonimide) (LiTFSI) are fabricated via a solvent free process. Field emission-scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and differential scanning calorimetry techniques are used to characterize the morphological features of the SPEs. The self-supported blend SPEs have sufficient mechanical strength and electrochemical stability compared to the pristine PEO electrolyte. The SPE2 (30 wt% LiTFSI in PEO:WPU = 3:1) electrolyte presents the superior comprehensive performance with a stress of 1.3 MPa and electrochemical window exceeding 4.8 V. All-solid-state LiFePO 4 /SPE2/Li cell using this blend solid polymer electrolyte exhibits both superior discharge capability and cycle performance (high initial discharge capacity of 160 mAh g −1 at 0.2 C, 122 mAh g −1 discharge capacity and 96% capacity retention after 100 cycles at 1 C) at 80 °C. All of these results demonstrate that this new WPU/PEO blend solid polymer electrolyte is a promising candidate for all-solid-state lithium ion batteries .