Morphology and ionic conductivity of solid polymer electrolytes based on polyurethanes with various topological structures

Polyurethanes with linear, hyperbranched and comb-crosslinked structures were synthesized and were used to prepare solid polymer electrolytes. The polymer electrolytes were characterized by means of Fourier transform Raman spectroscopy, impedance spectroscopy (IS) and atomic force microscopy (AFM). The results showed that salt concentration significantly influences the morphology and conductivity of the three kinds of polyurethane/LiClO4 system. When the mole ratios of the ether oxygen atom to lithium ion were controlled to be 12, 4 and 4 respectively for linear, hyperbranched and comb cross-linking polyurethane, the electrolytes typically displayed micro-phase separated morphology and the ionic conductivity also reached maxima respectively at 2.2 × 10−7 S/cm, 2.8 × 10−6 S/cm and 2.8 × 10−5 S/cm at room temperature.