Achieving Planar Electroplating/Stripping Behavior of Magnesium Metal Anode for a Practical Magnesium Battery

Sufficient evidence suggests that magnesium (Mg) metal battery is prone to short circuit even at extremely low current density (0.01 mA cm–2) when a practical polyolefin separator is used. The island-like Mg deposits caused by the high lattice mismatch of the substrate have been demonstrated to be the culprit for the short circuit. Although the single-crystal Mg substrate with the exposure of only the (0001) face has first been employed to promote the planar Mg deposits, the accompanying uneven Mg stripping behavior still triggers the short circuit during the cycling process. The delicately decorated three-dimensional (3D) substrate exhibits low lattice misfit with the (0001) face of Mg metal and rich magnesiophilic sites, which enable stable charge–discharge under a large areal capacity (4 mAh cm–2) and the thin polypropylene separator (25 μm). Establishing a layer-by-layer planar growth model and the design strategy of 3D magnesiophilic substrate will accelerate the commercialization of Mg metal batteries.