Surface Charge-Modulated Electric-Double-Layer Structure on Pt Catalyst for Efficient and Durable Sulfur Reaction in...

The sulfur conversion in lithium-sulfur (Li-S) batteries is largely hindered by sluggish conversion kinetics. Although highly active metal catalysts can promote this process, the intrinsic imbalance between electron transfer and ion transfer at the catalyst surface often leads to rapid passivation. Here, we address this critical challenge, particularly for highly active platinum (Pt) catalysts, by optimizing the electric double layer (EDL) at the catalyst-electrolyte interface, thereby enabling efficient and durable sulfur catalysis for high-energy Li-S batteries. The EDL structure is tuned by controlling the Pt surface charge density, achieved by grafting functional groups with varying electronegativities onto the carbon support to drive interfacial electron transfer from carbon to Pt. Using amine-functionalized carbon nanotube support to moderately increase charge density on Pt surface, we establish a well-balanced EDL that synchronizes coupled electron- and ion-transfer processes. This equilibrium facilitates efficient sulfur conversion while suppressing Pt sulfuration, maintaining a low activation energy (∼0.33 eV) throughout the sulfur reduction reaction. Consequently, the corresponding batteries achieve 70% capacity retention under practical conditions after 300 cycles. A 2.0 Ah pouch cell delivers a high energy density of 516 Wh kg^-1. This work provides an effective strategy to design sulfuration-tolerant catalysts toward practical Li-S batteries.