Uneven Stripping Behavior, A killer of Mg Anode in Mist

Uniform magnesium (Mg) plating/striping under high areal capacity utilization is critical for the practical application of Mg metal anode in rechargeable Mg batteries. However, the Mg metal anode failure has raising concerns when cycling under practical areal capacity (> 4 mA h cm ) . The mechanism behind these failures remains controversial. In this work, we illustrate that the initial plating Mg can be undoubtedly uniform in wide range of current densities (≤ 5 mA cm ) and under a practical areal capacity (6 mA h cm ) . However, an unusual self-accelerating pit growth is observed in the Mg stripping side under the moderate current densities (0.1-1 mA cm ), which severely deteriorates the anode integrity and subsequent Mg plating uniformity, causing Mg metal anode failure or short circuit of battery. The stripping morphology depends on the applied current density, as non-uniformity versus the current density displays a volcano plot during the stripping process. Through in-situ spectroscopy, we illustrate that this current dependent behavior is determined by the evolution of chlorine-containing complex ions near the interface. This research reminds that the plating/stripping process of Mg metal anode must be considered comprehensively for the practical Mg metal batteries. This article is protected by copyright. All rights reserved.