Rechargeable metal (Li, Na, Mg, Al)-sulfur batteries: Materials and advances

Energy and environmental issues are becoming more and more severe and renewable energy storage technologies are vital to solve the problem. Rechargeable metal (Li, Na, Mg, Al)-sulfur batteries with low-cost and earth-abundant elemental sulfur as the cathode are attracting more and more interest for electrical energy storage in recent years. Lithium-sulfur (Li-S), room-temperature sodium-sulfur (RT Na-S), magnesium-sulfur (Mg-S) and aluminum-sulfur (Al-S) batteries are the most prominent candidates among them. Many obvious obstacles are hampering the developments of metal-sulfur batteries. Li-S and Na-S batteries are encumbered mainly by anode dendrite issues, polysulfides shuttle and low conductivity of cathodes. Mg-S and Al-S batteries are short of suitable electrolytes. In this review, relationships between various employed nanostructured materials and electrochemical performances of metal-sulfur batteries have been demonstrated. Moreover, the selections of suitable electrolytes, anode protection, separator modifications and prototype innovations are all crucial to the developments of metal-sulfur batteries and are discussed at the same time. Herein, we give a review on the advances of Li-S, RT Na-S, Mg-S and Al-S batteries from the point of view of materials, and then focus on perspectives of their future developments.