Texture Evolution during Zinc Electrodeposition

Monday, 25 May 2015: 11:05
PDR 4 (Hilton Chicago)
C. Orme (Lawrence Livermore National Laboratory), J. Keist, P. K. Wright, and J. W. Evans (U. C. Berkeley)
This talk investigates the impact of additives and ionic liquids on the stability of zinc interfaces by measuring the temporal evolution of the surface roughness. Experiments are designed to quantify the morphological evolution during charge and discharge cycles in battery electrolytes. We use of in situ electrochemical atomic force microscopy and in situ ultra-small angle x-ray scattering (EC USAXS) to track surface morphology during zinc electrodeposition from two electrolytes: alkaline potassium hydroxide and an ionic liquid, 1-butyl-3-methyl-imidazolium trifluoromethanesulfonate (BMIM OTF). Images are used to quantify the temporal evolution of lateral correlations and surface roughness as a function of deposition thickness.

 Zinc growth within BMIM OTF displays a surface morphology that has not been described for zinc before; the surface organizes into domains of parallel platelets with the prism facets perpendicular to the surface. Because of this textured morphology, the surface roughness stops growing under some conditions. This cessation of roughening is counter to current models of surface evolution. The coarsening of the grains and the evolution of the roughness are quantitatively described using scaling exponents.  The goal of our project is to link early time nucleation events with the onset of large-scale instabilities such as dendrites.

 Auspices: Portions of this work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.