Identification of Li battery electrolyte degradation products through direct synthesis and characterization of alkyl carbonate salts

Aiming toward the identification of carbonate-based electrolyte degradation species formed during high- temperature cycling of Li/M-O cells, we have embarked in the synthesis and characterization of lithium-based alkyl carbonates. Through the reaction of commercial or synthesized lithium alkoxides with carbon dioxide, we succeeded in preparing lithium methyl, ethyl, propyl mono carbonates, and therefore we have extended our work to the synthesis of lithium ethandiol-bis carbonate. Their analytical characterization (H-1 and C-13 nuclear magnetic resonance, electrospray ionization- mass spectroscopy, Fourier transform: infrared/attenuated total reflection) is described. Furthermore, to our surprise, we managed to demonstrate that these well-known alkyl carbonates show some electrochemical reactivity toward Li. (c) 2005 The Electrochemical Society.