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Ethyl methyl carbonate (EMC) is an asymmetric aliphatic organic carbonate. It is a colorless transparent liquid widely used as an excellent solvent for lithium-ion battery electrolytes. EMC increases the solubility of lithium ions improving the capacity density and power of batteries. This compound has excellent thermal conductivity and low electrical resistance, extending the working temperature range of electrolytes, improving lithium batteries' safety, and prolonging their service life. EMC is usually obtained by metal oxide-catalyzed transesterification over dimethyl carbonate and diethyl carbonate. High percentage yields are obtained if the reaction is carried out in liquid or vapor phase[1].

Non-aqueous solvent for Li-ion batteries

Ethyl methyl carbonate enables the largest reversible capacity, best cycle stability, highest cycle Coulombic efficiency, lowest onset potential, smallest polarization, lowest self-discharge rate, and best rate performance from graphite compared to dimethyl carbonate and diethyl carbonate. Ethyl methyl carbonate forms a thinner layer of cathode electrolyte interface on the graphite surface with fewer Li–F and ROCO2Li species than with dimethyl carbonate and diethyl carbonate[2].

[1] Guido N. Rimondino , Fabio E. Malanca, Jesús A. Vila . “Atmospheric oxidation of ethyl methyl carbonate: Kinetics and reaction mechanism.” Journal of Photochemistry and Photobiology A-chemistry 444 (2023): Article 114994.
[2] Yao Wang. “Unlocking the True Capability of Graphite-Based Dual-Ion Batteries with Ethyl Methyl Carbonate Electrolyte.” ACS Applied Energy Materials 2 10 (2019): 7512–7517.