Dynamics of lithium stripping on graphite electrodes after fast charging

Abstract

Safe and reliable fast charging of lithium-ion batteries is contingent upon the development of facile methods of detection and quantification of lithium plating. Among the leading candidates for online lithium plating detection is analysis of the voltage plateau observed during the rest or discharge phase ensuing a charge. In this work, an operando metric, “S-factor,” is developed from electrochemical data to quantitatively analyze the severity of lithium plating over a range of charge rates and temperatures. An in situ visualization method is employed to study the physical mechanisms and phase transitions occurring at the graphite electrode during the voltage plateau. Here, we report that plated electrodes with significant state of charge heterogeneity exhibit multiple voltage plateaus and a higher proportion of irreversible plating. Cell characterization using S-factor and coulombic inefficiency helps in identifying the zone of opportunity with highly reversible lithium plating, facilitating development of safe and reliable fast-charging algorithms.