Dynamic Reconstruction of Polysulfides to Elemental Sulfur Enabling High‐Performance Ah‐Level Lithium‐Sulfur Pouch Cells

Abstract Lithium‐sulfur (Li‐S) batteries represent a promising high‐energy‐density secondary battery technology, with a theoretical energy density of 2600 Wh kg −1 . However, its performance is still hindered by the polysulfide (LiPS) shuttle effect, leading to the active material loss and anode electrode interface failure. Herein, a dynamic polysulfide reconstruction strategy is reported employing 5‐fluoroisatonic anhydride (FAIn) in the electrolyte as a reversible regulator that chemically reacts with the dissolved polysulfides, reconstituting them into elemental sulfur and thereby suppressing the polysulfide shuttle effect. During charging, the reaction products (Li‐FAIn) are electrochemically oxidized to regenerate the FAIn regulator, preserving the FAIn additive's dynamic equilibrium in the electrolyte. As a result, our design enables Li‐S pouch cells to retain 726 mAh g −1 after 199 cycles at 0.5 C (80% retention), with Ah‐level cells achieving 100 cycles at this rate. This study presents an efficient dynamic polysulfide reconstruction strategy through FAIn incorporation, providing a novel approach to suppress shuttle effects and enhance battery performance.