Current Status and Future Prospects of Metal–Sulfur Batteries

Lithium–sulfur batteries are a major focus of academic and industrial energy-storage research due to their high theoretical energy density and the use of low-cost materials. The high energy density results from the conversion mechanism that lithium–sulfur cells utilize. The sulfur cathode, being naturally abundant and environmentally friendly, makes lithium–sulfur batteries a potential next-generation energy-storage technology. The current state of the research indicates that lithium–sulfur cells are now at the point of transitioning from laboratory-scale devices to a more practical energy-storage application. Based on similar electrochemical conversion reactions, the low-cost sulfur cathode can be coupled with a wide range of metallic anodes, such as sodium, potassium, magnesium, calcium, and aluminum. These new “metal–sulfur” systems exhibit great potential in either lowering the production cost or producing high energy density. Inspired by the rapid development of lithium–sulfur batteries and the prospect of metal–sulfur cells, here, over 450 research articles are summarized to analyze the research progress and explore the electrochemical characteristics, cell-assembly parameters, cell-testing conditions, and materials design. In addition to highlighting the current research progress, the possible future areas of research which are needed to bring conversion-type lithium–sulfur and other metal–sulfur batteries into the market are also discussed.