LiBOB-based electrolytes for Li-ion batteries for transportation applications

The low-temperature performance and the stability of LiBOB-based electrolytes were studied in Li-ion cells and on various cathode materials, respectively. It was found that the conductivity of LiBOB in carbonate solvents can be improved by blending with ester solvents. It was also found that the capacity delivered using such electrolytes at subzero temperatures can be improved by adding ester solvents into electrolyte compositions, although at the expense of the stability against high-temperature cycling. The BOB- anion remains electrochemically stable on strongly oxidizing electrode material such as LiNi1-y-zMyMz'O-2 as shown by high-temperature cycling and storage. Nonetheless, the BOB- stability may vary with different cathode materials depending on the reactivity among BOB- anion, solvent, and lithiated metal oxide cathode materials. To maximize the advantages of LiBOB over the industry standard LiPF6, further work in electrolyte formulation is desired. (C) 2004 The Electrochemical Society.