Methodology for precise measurement of ion transport properties of semi-solid polymer electrolytes

Ion transport properties such as ionic conductivity, diffusion coefficients, effective transference numbers, and interphase resistance are some of the most important electrochemical properties of polymer battery electrolytes. Precise measurement of those, particularly when polymers are of low molecular weight and in a semi-solid phase, is difficult. Here we develop an improved measurement methodology including cell development, give theoretical background necessary for the detailed understanding, and test those on high weight percent, 40–60 wt %, lithium bis(trifluormethylsulfonyl)imide salt in polyethylene oxide model system with low M w between 2000 and 6000. We also give guidelines on how such experiments may go wrong, and the specific problems that occur.