Chemical additives for liquefied gas electrolytes

An electrochemical device, comprising:

• an ionically conducting electrolyte comprising a liquefied gas solvent, an organic liquid ester, and a salt, wherein:
• the liquefied gas solvent has a vapor pressure above 100 kPa at a temperature of 293.15K;
• the salt is soluble in the liquefied gas solvent;
• and
• the organic liquid ester is soluble in the liquefied gas solvent such that the ionically conducting electrolyte is a liquid under pressure;
• a first electrode and a second electrode in contact with the ionically conducting electrolyte;
• a housing that encloses the ionically conducting electrolyte, the first electrode and the second electrode, and maintains the electrolyte under sufficient pressure to keep the liquefied gas solvent in a liquid state at room temperature during normal operation, wherein the housing is a sealed cell housing that does not include a gas inlet or a gas outlet configured for continuous purging of gaseous reactants during normal operation of the electrochemical device;
• and
• wherein the liquid organic ester is configured to increase the solubility of the salt in the electrolyte, to decrease the viscosity of the electrolyte, to improve the ionic conductivity of the electrolyte, and to participate in the formation of a stable solid electrolyte interphase film on a surface of at least one of the first electrode or the second electrode.