Interfacial Effects on Transport Coefficient Measurements in Li-ion Battery Electrolytes

Development of Li + -containing electrolytes with improved transport properties requires reliable, reproducible, and ideally low volume techniques to rigorously understand ion-transport varying composition. Precisely measuring the complete set coefficients in liquid under battery-relevant operating conditions is difficult reliability these methods are sparsely described electrolyte literature. In this work, we apply a potentiostatic polarization-based characterization approach typically used for polymer systems an attempt fully measure all (conductivity, total salt diffusion coefficient, thermodynamic factor transference number) model system LiPF 6 ethylene carbonate—ethyl methyl carbonate (EC:EMC) mixture. Using systematic timescale statistical analyses, find that measured using polarization Li-Li symmetric cells exhibit strong correlation electrode interfacial resistance, indicating such probing both bulk phenomena. This reveals major roadblock characterizing where resistance significantly larger than ohmic resistance. As result, rely on metal stripping/plating do not readily result reliable coefficients, unlike similar solid electrolytes, resistances smaller at elevated temperatures interest electrolytes.