Practical energy densities, cost, and technical challenges for magnesium‐sulfur batteries

Amid burgeoning environmental concerns, electrochemical energy storage has rapidly gained momentum. Among the contenders in the “beyond lithium” energy storage arena, the magnesium‐sulfur (Mg/S) battery has emerged as particularly promising, owing to its high theoretical energy density. However, the gap between fundamental research and practical application is still hindering the commercialization of Mg/S batteries. Here, through reviewing the recent developments of Mg/S batteries technologies, especially with respect to energy density and cost, we present the primary technical challenges on both materials and device level to surpass the energy density and cost‐effectiveness of lithium‐ion battery. While the high electrolyte‐sulfur ratio and the expensive liquid electrolyte are significantly limiting the practical application of Mg/S batteries, we found that solid‐state Mg electrolyte appears to be a feasible solution on the basis of energy density and cost evaluation.