Passivation Dynamics in the Anisotropic Deposition and Stripping of Bulk Magnesium Electrodes During Electrochemical Cycling

Although rechargeable magnesium (Mg) batteries show promise for use as a next generation technology for high-density energy storage, little is known about the Mg anode solid electrolyte interphase and its implications for the performance and durability of a Mg-based battery. We explore in this repor...

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Bibliographic Details
Published in:ACS applied materials & interfaces 2015-08, Vol.7 (33), p.18406-18414
Main Authors: Wetzel, David J, Malone, Marvin A, Haasch, Richard T, Meng, Yifei, Vieker, Henning, Hahn, Nathan T, Gölzhäuser, Armin, Zuo, Jian-Min, Zavadil, Kevin R, Gewirth, Andrew A, Nuzzo, Ralph G
Format: Article
Language:English
Subjects:
columnar growth
corrosion
INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
magnesium anode
MATERIALS SCIENCE
passivation
rechargeable magnesium battery
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Summary:Although rechargeable magnesium (Mg) batteries show promise for use as a next generation technology for high-density energy storage, little is known about the Mg anode solid electrolyte interphase and its implications for the performance and durability of a Mg-based battery. We explore in this report passivation effects engendered during the electrochemical cycling of a bulk Mg anode, characterizing their influences during metal deposition and dissolution in a simple, nonaqueous, Grignard electrolyte solution (ethylmagnesium bromide, EtMgBr, in tetrahydrofuran). Scanning electron microscopy images of Mg foil working electrodes after electrochemical polarization to dissolution potentials show the formation of corrosion pits. The pit densities so evidenced are markedly potential-dependent. When the Mg working electrode is cycled both potentiostatically and galvanostatically in EtMgBr these pits, formed due to passive layer breakdown, act as the foci for subsequent electrochemical activity. Detailed microscopy, diffraction, and spectroscopic data show that further passivation and corrosion results in the anisotropic stripping of the Mg {0001} plane, leaving thin oxide-comprising passivated side wall structures that demark the {0001} fiber texture of the etched Mg grains. Upon long-term cycling, oxide side walls formed due to the pronounced crystallographic anisotropy of the anodic stripping processes, leading to complex overlay anisotropic, columnar structures, exceeding 50 μm in height. The passive responses mediating the growth of these structures appear to be an intrinsic feature of the electrochemical growth and dissolution of Mg using this electrolyte.
ISSN:1944-8244
1944-8252
DOI:10.1021/acsami.5b04487