Simultaneous Suppression of Metal Corrosion and Electrolyte Decomposition by Graphene Oxide Protective Coating in Magnesium-Ion Batteries: Toward a 4-V-Wide Potential Window.

Despite remarkable developments in electrolyte systems over the past 2 decades, magnesium-ion batteries still suffer from corrosion susceptibility and low anodic limits. Herein we describe how graphene oxide (GO), coated onto non-noble metals (Al, Cu, and stainless steel) via electrophoretic deposition, can solve this problem. In all phenyl complex electrolytes, GO coating results in a significant suppression of corrosion and extends the anodic limits (up to 4.0 V vs Mg/Mg2+) with no impact on reversible Mg plating/stripping reactions. The same effect of GO coating is also established in magnesium aluminum chloride complex electrolytes. This remarkable improvement is associated with the electrostatic interaction between the ionic charges of electrolytes and the surface-functional groups of GO. In addition, GO coating does not aggravate the cathode performance of Mo6S8, which allows the use of non-noble metals as current collectors. We also discuss the role of GO in increasing anodic limits when it is hybridized with α-MnO2.