A facile synthetic route for the development of a new class of dilithium salts is described. Because of the presence of two lithium ions per molecule, these salts require lower concentrations than commonly used salts to achieve comparable ionic conductivities at ambient temperatures. An ionic conductivity of 3.55 x 10(-3) S/cm at 30 degrees C was obtained using 0.5 M salt solution in 1:1 wt/wt ethylene carbonate: di methyl carbonate. The salts exhibit excellent thermal stabilities to at least 350 degrees C and are electrochemically stable below 4.2V versus lithium metal. The best salt was tested with a polymer electrolyte system. Incorporation of a polyethylene glycol-based borate ester plasticizer improved the ionic conductivity ofthe solid polymer electrolyte film up to 1.36 x 10-S-5/cm at 30 degrees C, which is 10 times higher than that of un-plasticized electrolyte films. (C) 2009 Elsevier B.V. All rights reserved.