Intimate Heterostructured Electrocatalyst for Functional Tandem Catalysts of Lithium Polysulfides in Separator‐Modified Lithium‐Sulfur Batteries

ABSTRACT Developing electrocatalysts to inhibit polysulfide shuttling and expedite sulfur species conversion is vital for the evolution of Lithium‐sulfur (Li‐S) batteries. This work provides a facile strategy to design an intimate heterostructure of MIL‐88A@CdS as a sulfur electrocatalyst combining high sulfur adsorption and accelerated polysulfide conversion. The MIL‐88A can give a region of high‐ordered polysulfide adsorption, whereas the CdS is an effective nanoreactor for the sulfur reduction reaction (SRR). Notedly, the significant size difference between MIL‐88A and CdS enables the unique heterostructure interactions. The large‐size MIL‐88A ensures a uniform distribution of CdS nanoparticles as a substrate. This configuration facilitates control of the initial polysulfide adsorption position relative to its final deposition site as lithium sulfide. The heterostructure also demonstrates rapid transport and efficient conversion of lithium polysulfides. Consequently, the Li‐S battery with MIL‐88A@CdS heterostructure modified separator delivers exceptional performance, achieving an areal capacity exceeding 6 mAh cm⁻², an excellent rate capability of 980 mAh g⁻¹ at 5 C, and notable cycling stability in a 2 Ah pouch cell over 100 cycles. This work is significant for elucidating the relationship between heterostructure and electrocatalytic performance, providing great insights for material design aimed at highly efficient future electrocatalysts in practical applications.