Regulating interfacial desolvation via a weakly coordinating solvent molecule enhances Li-ion storage at subzero temperatures

Abstract

Li-ion batteries (LIBs) suffer from severe capacity recession at subzero temperatures due to the dramatic increase in charge transfer resistance induced by the sluggish desolvation process. In this paper, we report on by using the weakly coordinating molecule as electrolyte (1 M LiPF6 in EC: DMC: PC = 1:1:1 vol%), the cell with MoS2 as the model electrode exhibits better cycling performance and rate capability than the cell using commercial electrolytes (1 M LiPF6 in EC: DMC = 1:1 vol%). Theoretical calculations and infrared spectroscopy indicate that PC is a weakly coordinated electrolyte molecule to Li+. Further, the electrochemical kinetics indicates that more Li+ in the as-made electrolyte can intercalate into the MoS2 layer. The electrochemical impedance spectroscopy reveals that the weak interaction between Li+ and solvent molecules reduces the activation energy of desolvation process. This novel design concept opens up new paths to exploit the advanced electrolyte for LIBs.