Liquid-Solid Phase Diagrams for Lithium-Ion Battery Electrolytes in the Ternary Space and Beyond

Although practical lithium-ion battery electrolytes generally utilize two or more solvents in addition to the dissolved lithium salt, liquid-solid phase diagrams have, as far as the authors know, only been reported for binary single-solvent electrolytes. This precludes rational design of low freezing point liquid electrolyte mixtures. We herein present a thermodynamic framework to draw out ternary electrolyte liquidus surfaces using the comprising binary liquid-solid equilibria data and limited ternary data measured via calorimetry. LiPF 6 in liquid carbonate mixtures are here studied. The introduced thermodynamic framework also allows evaluation of the thermodynamic factor, which appears in the context of transport parameter measurements.