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

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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. LiPF6 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.