Progress and Prospects of Emerging Potassium–Sulfur Batteries

The potassium–sulfur battery (K–S battery) as an innovative battery technology is a promising candidate for large-scale applications, due to its high energy density and the low cost of both K and S. The development of the K–S technology is, however, inhibited by its low reversible capacity and the safety issues related to the K metal anode. Here, the review starts by discussing the mechanism of the redox reactions for the K–S batteries and emphasizes the challenges for this battery system based on its current research status. Furthermore, the current improvement strategies for the K–S system in terms of the sulfur cathode, electrolyte, separator, and K metal anode are summarized. Finally, future perspectives on the development of the K–S system are proposed.