Interfacial Polysulfide Confinement via Spatially Controlled Sulfonated Metal–Organic Polyhedra Coatings in Lithium–Sulfur Batteries

ABSTRACT Lithium‐sulfur (Li‐S) batteries offer a high theoretical specific energy of 2600 Wh kg ⁻¹ , yet commercialization remains limited by poor sulfur conductivity and structural instability of sulfur electrodes due to polysulfide (Li‐PS) dissolution and shuttling. Here, a sulfonated zirconium‐based metal organic polyhedron (SMOP) is introduced as a molecularly dispersible additive for nanoscale interfacial engineering at 3 wt.% in the sulfur–carbon composite. Two placement modes are implemented, where SMOP is assembled as a conformal interfacial coating on sulfur‐loaded hollow carbon spheres (SMOP‐S‐HCS), whereas SMOP is introduced by co‐deposition/physical blending with Ketjen black (SMOP‐S‐KB), producing a dispersed/buried distribution without a defined surface layer. SMOP‐S‐HCS delivers a low shuttle charge ( Q _PS ) of 54.0 mAh g _S ⁻¹ , whereas SMOP‐S‐KB exhibits approximately 1.7‐fold higher Q _PS despite identical SMOP loading during the Li‐PS shuttle current measurement. SMOP‐S‐HCS delivers robust rate capability with discharge capacity ranging from ∼1500 to ∼800 mAh g _S ⁻¹ from 0.05 to 2C and sustained discharge capacity of 850 mAh g _S ⁻¹ after 400 cycles at 0.3C. Ex situ sulfur K‐edge XAS confirms the effectiveness of SMOP functional barrier against Li‐PS shuttling by probing more reversible sulfur speciation and reduced oxidized sulfur buildup during cycling.