Balancing Transport-Accessible Catalytic Interfaces and Li⁺ Transport via Porosity Engineering for High-Performance Li–S Batteries

The sluggish conversion of lithium polysulfides (LiPSs) to Li₂S represents the rate-determining step in lithium sulfur (Li–S) batteries. While catalytic sulfur hosts have been extensively investigated to accelerate the sulfur redox reaction (SRR), the effect of host architecture in governing Li⁺ transport and SRR kinetics remains insufficiently understood. Here, 2D Co₃S₄ with tunable architectures is employed as a model electrocatalyst to elucidate this structural influence. Combined experimental analyses and COMSOL simulations reveal an intrinsic trade-off between catalytic material packing and transport-accessible interfacial activity: increasing structural compactness in dense Co₃S₄ concentrates catalytic material but simultaneously increases Li⁺ transport resistance and concentration polarization, whereas porous frameworks facilitate Li⁺ migration and suppress concentration gradients. An optimized porous Co₃S₄ architecture balances accessible catalytic interfaces with efficient Li⁺ transport, thereby accelerating SRR kinetics and regulating Li₂S deposition. As a result, Li–S cells incorporating this optimized Co₃S₄ host deliver long-term cycling stability, retaining 657 mAh g⁻¹ at 0.2 C with a low-capacity decay of 0.051% per cycle over 1000 cycles. These findings establish porosity engineering as a critical design principle for catalytic sulfur hosts in high-performance Li–S batteries.