A safe electrolyte comprising a liquefied gas solvent that will transition from a liquid state to a gas state (“gas off”) at a pressure of 100 kPa and a temperature of 293.15 K is disclosed. A first mixture is formed from a first electrolyte component (one or more solvents) mixed with a second electrolyte component (one or more hydrocarbon co-solvents). The addition of the second electrolyte component (1) lowers the vapor pressure of the first mixture by at least 10% as compared to the vapor pressure of the first electrolyte component alone, when measured at 293.15 K, and (2) results in a vapor pressure of the first mixture above 100 kPa at a temperature of 293.15 K. The second electrolyte component may also be selected to lower the global warming potential (GWP) of the first mixture by at least 10% as compared to the GWP of the first electrolyte component alone. The safe liquefied gas electrolyte is formed by mixing a third electrolyte component (one or more salts) to the first mixture. This safe liquefied gas electrolyte can then be used to manufacture an electrochemical energy storage device.