Inhibition of polysulfide diffusion in lithium sulfur batteries: mechanism and improvement strategies

Lithium sulfur batteries present an attractive energy storage option because of their high energy density. However, the shuttle effect leads to a series of problems that hinder their commercialization. The shuttling effect is caused by the dissolution, diffusion, and side reactions of polysulfides, which can be suppressed by inhibiting the diffusion of polysulfides. Thus, many methods had been developed to impede the diffusion of polysulfides, thereby improving the cycle stability and capacity of lithium sulfur batteries. Throughout the dissolution and diffusion processes of polysulfides, the sulfur electrode and the separator are two key locations to influence the diffusion of polysulfides. At each position, the methods of limiting polysulfides diffusion can be further divided into physical and chemical methods according to the mechanism of interaction between host materials and polysulfides. This review summarizes various methods of limiting polysulfides and discusses their mechanisms of action in depth, which can help to understand the advantages and disadvantages of each method. Finally, based on recent development of lithium sulfur batteries, the future perspectives of methods for limiting the diffusion of polysulfides have been proposed.