Solid polymer electrolyte based on thermoplastic polyurethane and its application in all-solid-state lithium ion batteries

In this paper a new kind of solid polymer electrolyte (SPE) based on thermoplastic polyurethane (TPU) is fabricated. With the dispersion of Li7La3Zr2O12 powders, the lithium ionic conductivity of the SPE can be improved effectively. By optimizing the amount of Li7La3Zr2O12, an ionic conductivity of 8.89 × 10− 5 S cm− 1 at 80 °C is achieved. X-ray diffraction and scanning electron microscopy are employed to analyze the crystallinity and microstructure of the SPE samples. The all-solid-state lithium ion cells with the TPU-based SPE as solid electrolyte and LiFePO4 as active cathode material are assembled through a simple blade-coating method. Such all-solid-state cells exhibit a specific capacity (160 mAh g− 1) comparable with the traditional cells using organic liquid electrolyte at the current density of 5.3 μA cm− 2. To further investigate the electrochemical performances of the all-solid-state cells, the cyclic voltammetry and galvanostatic cycling are also performed and analyzed.