NOVEL WATERBORNE POLYURETHANE BASED ELECTROLYTES FOR LITHIUM BATTERIES-(IV) - THE INFLUENCE OF DMPA PEG RATIOS ON CONDUCTIVITY/

Three waterborne polyurethane (WPU) films with the molar ratios of dim ethylol propionic acid (DMPA) to polyethylene glycol (PEG) at 0.1, 1, and 3 were prepared by using our modified acetone process. The effects of DMPA/PEG on conductive behavior were investigated by comparing the ionic conductivity of these dry films, their gel-type films, and gel- type electrolytes. The gel-type films and gel-type electrolytes were p repared by impregnating the dry films with 50 wt% propylene carbonate (PC) and 1M LiClO4/PC, respectively. The ionic conductivity was determ ined by running alternating current (AC) impedance with stainless stee l (SS)/dry film/SS and Li/gel film/Li cells. Differential scanning cal orimetry (DSC) and polarizing microscopy (PM) were employed for materi al characterization to explain the reason for different conductivities . The room temperature conductivities of gel-type films and gel-type e lectrolytes are similar to 10(-5) S/cm and similar to 10(-4) S/cm, res pectively.