Lithium dendrite growth mechanisms in liquid electrolytes

A unified theoretical framework of dendrite growth kinetics has been developed to account for the coupled effects of electrodeposition, surface tension, and elastic and plastic deformation. The contribution of each driving force is assessed to identify five regimes of lithium growth: thermodynamic suppression regime, incubation regime, tip-controlled growth regime, base-controlled growth regime, and mixed growth regime, in agreement with the experimental scientific literature. Tip-controlled growth shows a linear time-dependence, while base-controlled growth shows an exponential time-dependence. A minimum in the growth rate, as a result of the reaction energy barrier increase imposed on the interface by the local elastic energy, is identified in the mixed growth regime. Further, two characteristic times are identified: the characteristic deposition time, t(o), which defines the critical time scale necessary to overcome the electrochemical energy barrier for nucleation, and the characteristic plasticity time, t(sigma), which corresponds to the time scale necessary for plastic flow to occur, given a local shear stress. Examples of experimentally reported transitions between tip-controlled growth and base-controlled growth are readily captured through the proposed framework. While one or more mechanisms may dominate the growth of the electrodeposit, the proposed formulation defines a road map to design dendrite-free, lithium-based anodes as a stepping stone to identify alternate dendrite-free chemistries.