Electrochemical properties of boric ester electrolytes with high potential cathode for lithium ion batteries

Introduction Lithium-ion batteries are currently produced on a large scale mainly as equipment for powering portable electronic devices, but simultaneously intensive research is carried out on the development of large and high power batteries for powering hybrid electric vehicles (HEVs) and plug-in HEVs. We have reported that boric ester electrolytes showed the high oxidation potential. Boric esters exhibit preferable physical and electrochemical properties that are tunable due to substituents R (Fig. 1). The boron atom possesses a vacant p-obital and thus Lewis acid. They are able to bind the counter anions of lithium salts and solvent molecules. Boric esters could be synthesized from inexpensive starting materials such as boric acid (B(OH)3) and alcohols. A boric ester is found to have a high oxidative stability, therefore the use of LiNi0.5Mn1.5O4 (LNM) can be expected. In this study, we measured charge-discharge of Li/LNM cell in boric ester electrolyte.