This work is dedicated to phosphoric acid esters working as solvents for lithium-ion and supercapacitor (SC) electrolyte. The electrical conductivity of electrolytes based on phosphoric acid esters, lithium salts, commonly used in lithium-ion batteries (LIB), and salts used in SC technology was measured. The thermodynamic stability of new electrolytes in comparison with other solvents used in chemical power sources technology was also estimated. It was shown that the thermodynamic stability of phosphoric acid ester increases in a homologous series.