Exploiting the Steric Effect and Low Dielectric Constant of 1,2-Dimethoxypropane for 4.3 V Lithium Metal Batteries

Abstract

1,2-Dimethoxyethane (DME) has been widely used as an electrolyte solvent for lithium metal batteries on account of its intrinsic reductive stability; however, its low oxidative stability presents a major challenge for use in high-voltage Li metal batteries (LMBs). In this direction, herein, we introduce a new low-dielectric solvent, 1,2-dimethoxypropane (DMP), as an electrolyte solvent. Compared to DME, DMP has decreased solvation power owing to its increased steric effects, thus promoting anion-Li+ interactions. This controlled solvation structure of the 2 M LiFSI-in-DMP electrolyte facilitated the formation of an anion-driven, stable interface at the lithium metal anode and oxidative stability for compatibility with widely adopted cathodes to afford Li|LiFePO4 and Li| LiNi0.8Co0.1Mn0.1O2 cells with decent cycling stability. These results imply the usefulness of steric control as an alternative strategy to commonly used fluorination to fine-tune the solvation power and, in general, the design of new solvents for practical lithium metal batteries.