Effective Electrolyte Combination Composed of 1,1-Diethoxyethane and Lithium Bis(fluorosulfonyl)imide for Dendrite-suppressible Li Metal Anodes

Abstract

Although Li metal is considered the most promising anode material owing to its high theoretical capacity, there are numerous restrictions on expanding its application because of undesired surface reactions occurring at the Li anode. To solve this, an effective electrolyte combination consisting of 1,1-diethoxyethane (DEE) and lithium bis(fluorosulfonyl)imide (LiFSI) is used in this work, which can provide an organic/inorganic-hybridized solid-electrolyte interphase (SEI) at the Li anode. The DEE solvent affords flexible carbon-abundant components, whereas LiFSI offers mechanically rigid lithium fluoride-type components; these undergo electrochemical reduction to form SEI layers that are balanced in terms of organic and inorganic components. Systematic analysis results exhibit that when the SEI layer integrated with DEE and LiFSI is embedded in the lithium anode, electrolyte decomposition, and dendritic lithium growth are suppressed in Li/Li cells, thereby improving surface stability. Similarly, it provides stable cycle life characteristics even at 150 cycles in Li/S cells (72.0% vs 52.6%).