Competitive Solid-Electrolyte Interphase Formation on Working Lithium Anodes

Abstract

It is critical to understand competitive solid-electrolyte interphase (SEI) formation on lithium (Li) metal anodes from a fundamental perspective. The solvation structure of lithium ions and the electric double-layer behavior at electrode/electrolyte interface are proposed as two primary principles to determine the preferential reduction reactions during SEI formation. The kinetic competition between SEI formation and Li deposition is elucidated, the results of which are strongly associated with the final Li electroplating morphology. Several internal and external parameters such as electrolyte formulation, current density, and temperature can be considered to modulate the SEI formation–Li deposition competition. The generation and evolutional behavior of the solid-electrolyte interphase (SEI) fatally dictate the performance of working anodes, especially lithium (Li) anodes. In this Opinion, we describe the critical rationale in understanding competitive SEI formation on a working Li metal anode. First, the fundamentals that determine the competitive SEI-forming reactions at the Li/electrolyte interface are analyzed. Moreover, we elucidate the kinetic competition between SEI growth and Li deposition in the case of exposure to fresh Li surfaces during the Li electroplating process. Several important factors involving electrolyte formulation, current density, and temperature that can intrinsically modulate the kinetic competition are comprehensively summarized. Finally, future research trends regarding dynamic SEI formation and its correlation with the manner of Li electroplating are addressed. The generation and evolutional behavior of the solid-electrolyte interphase (SEI) fatally dictate the performance of working anodes, especially lithium (Li) anodes. In this Opinion, we describe the critical rationale in understanding competitive SEI formation on a working Li metal anode. First, the fundamentals that determine the competitive SEI-forming reactions at the Li/electrolyte interface are analyzed. Moreover, we elucidate the kinetic competition between SEI growth and Li deposition in the case of exposure to fresh Li surfaces during the Li electroplating process. Several important factors involving electrolyte formulation, current density, and temperature that can intrinsically modulate the kinetic competition are comprehensively summarized. Finally, future research trends regarding dynamic SEI formation and its correlation with the manner of Li electroplating are addressed. the ratio of the total charge extracted from the battery to the total charge put into the battery over a full cycle. metallic electroplating behavior in a dendrite morphology. a structure that appears on the surface of an object when it is exposed to aqueous and nonaqueous media; a model typically used to visualize the ionic environment in the vicinity of a charged surface. a quantitative measure of Lewis basicity. the inner plane within the stern layer at the electrode/electrolyte interface, where the adsorbed species should be fully desolvated or partially desolvated. ionically conductive but electronically insulating interphase generated by the decomposition reaction of electrolyte. the average number of molecules bound to the compound.