Insights into the Degradation Mechanism of the Magnesium Anode in Magnesium–Chalcogen Batteries: Revealing Principles for Anode Design with a 3D-Structured Magnesium Anode

Magnesium–chalcogen batteries are promising post lithium battery systems for large-scale energy storage applications in terms of energy density, material sustainability, safety, and cost. However, the soluble reaction intermediates, such as polysulfides or polyselenides, formed during the electrochemical processes can severely passivate the Mg metal anode, limiting the cycle life of the batteries. It is necessary to rescrutinize the failure in Mg–chalcogen batteries from an anodic perspective. Herein, the Mg metal anode failure mechanism is thoroughly examined, revealing that it is induced by an inhomogeneous Mg deposition promoted by soluble intermediates from chalcogen cathodes. To further confirm the mechanism and solve this anode failure problem, a multifunctional 3D current collector is used to decrease the local current density and regulate the Mg deposition behavior. The present findings are anticipated to provide guidance for anode design, enhance the life-span of Mg–chalcogen batteries, and facilitate the development of other magnesium metal batteries.