Inhibition of Polysulfide Shuttles in Li-S Batteries: Modified Separators and Solid-State Electrolytes

Lithium-sulfur (Li-S) batteries are one of the most promising next-generation energy storage systems due to their ultrahigh theoretical specific capacity. However, their practical applications are seriously hindered by some inevitable disadvantages such as the insulative nature of sulfur and Li2S, volume expansion of the cathode, the shuttle effect of polysulfides, and the growth of lithium dendrites on the anode. Of these, the polysulfide shuttle effect is one of the most critical issues causing the irreversible loss of active materials and rapid capacity degradation of batteries. Herein, modified separators with functional coatings inhibiting the migration of polysulfides are enumerated based on three effects toward polysulfides: the adsorption effect, separation effect, and catalytic effect. To solve the shuttle effect problem, researchers have replaced liquid electrolytes with solid-state electrolytes. In this review, solid-state electrolytes for lithium-sulfur batteries are grouped into three categories: inorganic solid electrolytes, solid polymer electrolytes, and composite solid electrolytes. Challenges and perspectives regarding the development of an optimized strategy to inhibit the polysulfide shuttle for enhancing cycle stability in lithium-sulfur batteries are also proposed.