The invention relates to the use of aromatic phosphite compounds as stabilizers for nonaqueous electrolytic solutions containing halogenated salts such as LiPF.sub.6 and LiBF.sub.4. The electrolyte containing such a phosphite exhibits excellent shelf life storage at ambient and high temperatures. The electrolytic solution is suitable for use in electrochemical cells such as lithium (ion) rechargeable batteries and supercapacitors.