Rational design of bidirectional electrocatalysts and accelerated sulfur redox reactions in lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries have emerged as one of the most promising energy storage solutions. However, its commercial application still faces a significant challenge: the sluggish redox reaction kinetics of the reversible lithium polysulfide (LiPS) conversion process. The strategic design of cathode structures and electrocatalysts can help accelerate polysulfide conversion. In this study, systematic density functional theory (DFT) calculations predict that the incorporation of platinum (Pt) nanoparticles, as a model electrocatalyst, into biomass carbon materials can effectively promote the bidirectional conversion of polysulfides. Detailed kinetic analyses reveal that Pt-doped biomass carbon materials possess exceptional electrocatalytic abilities for Li2S nucleation and dissociation. These findings are further elucidated by ex situ X-ray photoelectron spectroscopy measurements, elucidating the bidirectional mechanism of Pt. The sulfur cathode delivers a remarkable specific discharge capacity of 1386.9 mAh g-1 at 0.1 C. Even more impressive is its potential for practical applications, exemplified by a high initial capacity of 1218.7/1015.3 mAh g-1 and excellent cycling stability under a high sulfur loading of 4.5/7.5 mg cm-2, which achieved substantial capacity retention (83.9/81.1%) after 100 cycles. This bidirectional electrocatalysis, achieved through the synergy of metal with biomass carbon materials, presents an attractive approach for advancing Li-S systems.