Lithium metal anodes are a promising choice to achieve high energy density compared to current graphite anodes. However, lithium whisker growth (dendrites) during battery charging poses a major safety and performance concern for both lithium metal batteries, and overcharging of presently used graphite anodes in lithium-ion batteries. The present understanding of lithium electrodeposit growth is largely based on the Diffusion Limited Aggregation theory that results in a tip-controlled growth of fractal or dendritic structures. However, lithium electrodeposits have been reported in scientific literature to grow from the base at low current densities [1,2,3], that cannot be explained solely by electrodeposition kinetics. In this work, the mechanisms of lithium growth on anodes are analyzed assessing the combined contribution of electrochemical and mechanical driving forces. Physical mechanisms for tip-controlled and base-controlled growth modes are developed based on a thermodynamically consistent formulation, and have been validated based on the available scientific literature. Analytical and numerical solutions are discussed.

References:

[1] F. Orsini, A. D. Pasquier, B. Beaudouin, J. M. Tarascon, M. Trentin, N. Langenhuizen, E. D. Beer, and P. Notten. "In situ SEM study of the interfaces in plastic lithium cells." J. Power Sources 81 (1999) 918-921.

[2] O. Crowther, A.C. West, “Effect of Electrolyte Composition on Lithium Dendrite Growth.” J. Electrochem. Soc., 155 (2008) 806-811

[3] P. Bai, J. Li, F. R. Brushett, M. Z. Bazant. “Transition of lithium growth mechanisms in liquid electrolytes.” Energy Environ. Sci. 9 (2016) 3221-3229