Monday, 14 October 2019: 15:00
Room 220 (The Hilton Atlanta)
Although Li-ion batteries are the state of the art in energy storage technologies, their lifespan and safety are reduced by a lack of understanding of the lithium plating phenomenon. Despite many years of research, the intricacies of the coupled thermal-electrochemical interactions that govern Li plating behavior remain surprisingly elusive. Some portion of plated Li can be reversibly stripped from the graphite and re-intercalated during either the rest or discharge phase following a charge in which Li plating occurred, but the factors affecting the degree of reversibility have yet to be uncovered. In order to induce Li plating experimentally, two strategies are widely employed: low rate overcharging of graphite beyond its intercalation limit (kinetically limited) and high rate/low temperature charging within the normal graphite intercalation range (transport limited). Although both strategies result in the electrodeposition of Li on the anode, the morphologies of these deposits may be markedly different, which in turn will affect how much of the Li becomes electrically isolated following re-intercalation. In this study, Li plating was induced in graphite half cells under both transport limited and kinetically limited scenarios in order to determine differences in degree of reversibility, plating morphology, and impedance characteristics. Coulombic inefficiency upon de-lithiation allowed for quantification of losses due to a combination of irreversible plating and SEI formation, while optical microscopy was used to characterize the morphology of Li deposits.
