Ultrathin Magnesium Metal Anode - An Essential Component for High-Energy-Density Magnesium Battery Materialization

The practical loading, i.e., thickness, of metal anodes predominates the practical energy density of batteries that incorporate elemental metals as anode active materials. Despite its significance for achieving high-energy-density rechargeable magnesium batteries (RMBs), the application of ultrathin magnesium foils remains a challenge because of the brittleness and unworkability of magnesium. This work provides a critical component of a geometric size applicable to laminate-type cells of dimensions 42 x 32 mm(2) or larger. Ultrathin magnesium foil without cracked edges can be fabricated by controlling the initial microstructure. Furthermore, the rolling temperature determines the resulting microstructure and thus the electrochemical properties. The optimal sample, a warm-rolled magnesium foil, exhibited excellent electrochemical characteristics owing to its favorable microstructure, which facilitated a homogeneous distribution of reaction sites. Battery performance using such ultrathin magnesium anodes was investigated with MgMn2O4 and alpha-MnO2 cathodes. Considering the weights of both the cathodes and anodes, the gravimetric energy density of primitive [alpha-MnO2 parallel to pMg] cells was estimated to be 72 Wh kg(electrode)(-1).

Automated summary

The practical energy density of batteries incorporating elemental metals as anode active materials is largely influenced by the thickness of the metal anodes. However, the use of ultrathin magnesium foils is challenging due to the brittleness and unworkability of magnesium. This study successfully fabricated crack-free ultrathin magnesium foils with favorable microstructure by controlling the initial microstructure and rolling temperature, and demonstrated their excellent electrochemical characteristics as anode materials.