Ethyl Methyl Carbonate as a Cosolvent for Lithium-Ion Cells

Ethyl methyl carbonate (EMC) has been found to be a suitable cosolvent, along with three other carbonate solvents, for incorporation into electrolytes to enhance the low-temperature performance of rechargeable lithium-ion electrochemical cells. EMC is an asymmetric aliphatic carbonate, and, as noted in the first of the two immediately preceding articles, asymmetric carbonates confer certain benefits. In the research described in that article, the asymmetric carbonates were formed in situ, in reactions catalyzed by lithium alkoxide additives. In contrast, the present finding that EMC is a suitable cosolvent was made by following a different approach; namely, formulating the electrolyte solvents to include an asymmetric aliphatic carbonate — EMC — in the first place.