In operando signature and quantification of lithium plating

Abstract

Lithium plating is a critical challenge for lithium intercalation battery chemistry, especially at high charge rates and high states of charge leading to reduced cycle life, capacity loss, and safety concerns. The anode-centric process of metallic lithium deposition can be identified by monitoring the anode potential in a full cell. In this study an in operando, three-electrode Li-ion pouch cell construct is proposed to probe and quantify lithium plating over a gamut of operational variability, combined with a comprehensive analysis including electrochemical, microscopy and spectroscopy signatures. Different regimes of capacity fade over cycling are identified with respect to the relative extent of lithium plating based on the plating energy as a descriptor. This study reveals the existence of a critical rate where the degradation due to lithium plating is minimal, which is a manifestation of the synergy between the kinetic processes and heat generation signatures. Different morphologies of lithium plating were observed, such as, localized agglomeration predominantly at rates exhibiting higher extent of plating, while diffuse characteristics at rates with lower amount of plating. The propensity for lithium plating and plating induced failure are found to increase with aging even at lower charge rates. This study comprehensively proffers the stochastic nature of the lithium plating process with operational variability.