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 Na _0.97 Ca _0.03 [Mn _0.39 Fe _0.31 Ni _0.22 Zn _0.08 ]O _2 (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 h of storage at 4 V and 40 °C, and maintaining over 80% capacity retention after 200 cycles up to 4 V at 40 °C. Severe gas evolution and Na plating issues are present in all the tested systems.

Keywords

• non-aqueous sodium-ion batteries
• electrolyte co-solvent
• carbonate
• failure mechanism