Non-aqueous liquid electrolytes in lithium metal battery: components and modification

Lithium metal is regarded as one of the most promising anode materials due to its intrinsic superiority including the lowest electrode potential (-3.04 V vs. SHE) and impressive theoretical specific capacity (3860 mAh g-1). Even though the study of lithium metal batteries (LMB) can be traced back to the 1970s, the practical promotion has been hindered by some substantial obstacles, such as the growth of dendrite and the low Coulombic efficiency. During the past decade, extensive investigative approaches have been devoted to stabilizing the deposition of lithium metal as well as inhibiting the undesirable parasitic reactions. Electrolytes play a crucial role in the deposition of lithium, and that explains the reason why a great deal of progress has been attained in this field. This review summarizes the representative work in recent years, including the optimization of conventional electrolyte components, as well as the novel materials in a solvent, Li salt, and additives. Moreover, high-concentration electrolytes and localized high-concentration electrolytes are summarized representing two fruitful fields, based on the emerging theories of lithium-ion coordination and solvation sheath layer. Finally, some prospects are proposed to lead us closer to the large-scale application of LMB.