Novel alkyl methyl carbonate solvents for lithium-ion batteries

Electrochemical cycling tests on cells with graphite electrodes and several alkyl methyl carbonates were performed. Experiments with single solvent electrolytes and binary mixtures with ethylene carbonate (EC) showed that the alkyl methyl carbonates H3CO(CO)O(CH2)nH (n=3–5) are suitable as co-solvents in lithium-ion batteries. Butyl methyl carbonate (BMC) showed the best performance in these experiments. Ternary mixtures of EC, BMC, and propylene carbonate (PC) allow cycling of cells with a graphite anode material that is otherwise incompatible with EC/PC electrolytes. This is probably because BMC-based electrolytes form the solid electrolyte interphase (SEI) at more positive potential than electrolytes based on PC.