Highly Dispersed Molybdenum Nanoclusters on Hierarchically Porous Carbon Foam for Enhanced Redox Reaction Activity in Li–S Batteries

Herein, hierarchically porous nitrogen-doped carbon foam with uniformly dispersed molybdenum nanoclusters were designed (Mo/NC). This structure not only provides continuous conductive pathways and abundant pore channels, but effectively adsorbs and promotes the reaction of lithium polysulfide (LiPSs), realizing an efficient bidirectional catalytic activity for LiPSs conversion and Li₂S dissociation. The theoretical calculation demonstrates that the Mo clusters show stronger affinity to LiPSs and lower energy barrier for Li₂S dissociation than the N active sites. Furthermore, the slurry with Mo/NC and polyvinylidene fluoride (PVDF) adhesive was coated on the polypropylene (PP) membrane by phase-exchange process for a composite separator (Mo/NC@ PVDF//PP), thus ensuring the porous networks and abundant exposure of Mo active sites in the Mo/NC catalyst. Cells assembled with the separator exhibit a cycle stability at 1.0 C with sulfur loading of 1.0 mg cm⁻², which remained 612 mAh g⁻¹ after 1000 cycles, indicating a fading rate of 0.065% per cycle. Even at a sulfur loading of 4.5 mg cm⁻ ², the cell retained a specific capacity of 610 mAh g⁻ ¹ after 350 cycles. The pouch cell delivers a capacity of 625 mAh g⁻ ¹ after 50 cycles at a sulfur loading of 3.7 mg cm⁻ ², showing promising for practical application.