Rigid-flexible Coupling Solid Polymer Electrolytes Based on Polyurethane

The polyurethane based polymer matrix was obtained from the block copolymerization between polyethylene glycol (PEG2000), 1, 4-phenylene diisocyanate (PDI) and hexamethylene diisocyanate (HDI), and the solid polymer electrolytes (SPEs) were fabricated by introducing lithium salts in the system additionally. The composition, structure and electrochemical properties of the prepared materials were also evaluated. The research results show that the crystallinity of PEG declines because of the copolymerization effect, which promotes the ionic conductivity of the prepared SPEs to be 7.4×10^-5 S/cm at room temperature. Additionally, owing to the combination of the rigidity from PDI and the flexibility from HDI, the tensile strength is 61.6 mPa, Young's modulus is 62.9 mPa, elongation at break is 65.6%, and tensile toughness is 22.7 MJ/m³. The discharge capacity of the solid-state lithium metal batteries assembled by the fabricated SPEs reaches 121.3 mAh/g at 0.1C after 100 cycles, indicating nearly 82% of the capacity maintaining.