Unraveling Shuttle Effect and Suppression Strategy in Lithium/Sulfur Cells by In Situ/Operando X‐ray Absorption Spectroscopic Characterization

By employing in situ/operando X‐ray absorption characterization, the veritable shuttle effect and its suppression/conversion strategy using bismuth‐based nanomaterials as electrocatalytic layer in lithium/sulfur cells are unraveled. The polysulfides shuttle effect represents a great challenge in achieving high capacity and long lifespan of lithium/sulfur (Li/S) cells. A comprehensive understanding of the shuttle‐related sulfur speciation and diffusion process is vital for addressing this issue. Herein, we employed in situ/operando X‐ray absorption spectroscopy (XAS) to trace the migration of polysulfides across the Li/S cells by precisely monitoring the sulfur chemical speciation at the cathodic electrolyte‐separator and electrolyte‐anode interfaces, respectively, in a real‐time condition. After we adopted a shuttle‐suppressing strategy by introducing an electrocatalytic layer of twinborn bismuth sulfide/bismuth oxide nanoclusters in a carbon matrix (BSOC), we found the Li/S cell showed greatly improved sulfur utilization and longer life span. The operando S K‐edge XAS results revealed that the BSOC modification was bi‐functional: trapping polysulfides and catalyzing conversion of sulfur species simultaneously. We elucidated that the polysulfide trapping‐and‐catalyzing effect of the BSOC electrocatalytic layer resulted in an effective lithium anode protection. Our results could offer potential stratagem for designing more advanced Li/S cells.