Morphology-Safety Implications of Interfacial Evolution in Lithium Metal Anodes

Dendrite formation and growth upon cycling pose major concerns toward lithium metal battery performance and safety. Herein, we present an interface-capturing formalism to study the morphological evolution of lithium metal anodes at time scales comparable to typical charging durations. This mesoscale study distinctly captures mossy/fractal growth patterns that manifest depending on the electrochemical environment of the lithium metal battery system and observed in in situ experimental electrodeposition studies. We further develop a safety map (pertaining to the short circuit via direct dendrite propagation) in terms of charged capacity and the limiting current density of the system. Examination of the safety map, in conjunction with the delineated morphological features (growth speed and interfacial area, in particular), allows deriving insights into probable cell failure modes. We deduce that the electrolyte starvation and solid electrolyte interphase reformation are more likely causes for cell failure, that are instigated at higher applied current densities than direct dendrite penetration itself.