Liquid electrolyte design for metal‐sulfur batteries: Mechanistic understanding and perspective

Metal‐sulfur batteries have received intensive research attention owing to their potential to achieve higher energy density and lower cost than conventional Li‐ion batteries. However, metal‐sulfur batteries suffer from a fundamental challenge, the shuttle effect, the crossover of soluble reaction intermediates polysulfide leading to low efficiency and poor cycle life. Electrolyte design becomes the center of the sulfur redox chemistry since it dictates the properties of the soluble polysulfide intermediates in metal‐sulfur batteries. Here, we discuss the influence of electrolytes on sulfur reactions and cell performance, focusing on the polysulfide chemistry including polysulfide solubility and metal sulfide deposition. Based on the extensive analysis of literature, we highlight the design requirement of electrolytes to enable optimized sulfur reaction kinetic and realize high‐performance metal‐sulfur batteries.