Hybridization of Ester Solvents for Wide-Temperature Operation Lithium-Ion Batteries

Carbonate-based electrolytes are commonly used in commercial Li-ion batteries (LiB). However, due to high melting point and de-solvation energy of carbonate solvents, such as Ethylene Carbonate (EC), Li-ion diffusion and charge transfer kinetics become sluggish at low temperatures. Herein, we introduce hybrid solvent with ester and ether functional group for wide temperature range operation. The unique oxygen spatial arrangement of such solvents allows for higher degree of electron-withdrawing effect compared to standard carbonates, leading to weaker binding energy with Li-ions. With the low melting point of hybrid solvents, the low solvation energy of hybrid solvents allows for faster charging even at subzero temperature. Several types of hybrid solvents were also investigated by changing the molecular weight, with different impact towards cell performance.