Effects of Electrolyte Composition on Lithium Plating in Lithium-Ion Cells

Abstract

Metallic lithium is typically absent in a lithium-ion (Li-ion) cell under normal conditions of operation. Under strenuous charge conditions of high charge rates and/or low temperatures, however, lithium metal will deposit on the carbon anode in preference to lithium intercalation, especially after considerable cycling and storage, which contribute to the degradation of anode capacity. Such plated lithium will react more readily in the Li-ion battery electrolytes and pose problems related to performance, reliability, and safety of the cell. Factors that affect the anode performance, specifically its polarization and lithium intercalation kinetics, play a crucial role in determining the propensity for lithium deposition. Such factors include the nature of solid electrolyte interphase (SEI), which is in turn governed by the electrolyte constituents, anode/cathode capacity ratios, and the operating conditions. In this paper, the Li intercalation kinetics and their impact on Li plating were studied with two sets of electrolytes containing different proportions of EC and with SEI-stabilizing additives. Electrolytes with low EC-formulations and those without SEI-stabilizing additives are relatively immune to lithium plating.