Communication — The Impact of Co-solvent Selection for Dimethyl-2,5-dioxahexane carboxylate in Sodium Ion Batteries

Abstract

Traditional linear carbonates including dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC) were investigated as co-solvents for the dimethyl-2,5-dioxahexane carboxylate (DMOHC)-based electrolyte in Na0.97Ca0.03[Mn0.39Fe0.31Ni0.22Zn0.08]O2 (NCMFNZO)/hard carbon (HC) pouch cells. The EMC-containing cell displays excellent electrochemical performance, exhibiting only a 1.6 mAh irreversible capacity loss during 500 hours of storage at 4V and 40°C, and maintaining over 80% capacity retention after 200 cycles up to 4V at 40°C. Severe gas evolution and Na plating issues are present in all the tested systems.