Unraveling Catalyst Migration in Li-S Batteries: Designing Stable Ni Single-Atom Catalysts

High Resolution Image Download MS PowerPoint Slide Lithium sulfur (Li-S) batteries are regarded as promising next-generation energy storage systems owing to their high theoretical capacity and low material cost. However, their practical application is limited by sluggish sulfur redox kinetics and severe polysulfide shuttle effect. Single-atom catalysts (SACs) have emerged as effective catalysts for accelerating polysulfide conversion; however, their long-term stability and degradation mechanisms remain poorly understood. In this study, we provide insights into a catalyst migration effect in Li-S batteries, revealed by the degradation of nickel phthalocyanine (NiPc), a molecular-type catalyst that undergoes structural collapse and migration. To overcome this limitation, the NiPc (pyrrole-based) molecular structure was transformed into a nitrogen-doped carbon-supported catalyst (Ni-NC, pyridinic-N anchored), thereby generating atomically dispersed Ni-N 4 sites immobilized within a conductive nanostructured carbon framework. This architecture promotes charge transfer, optimizes polysulfide adsorption, and ensures structural robustness, effectively suppressing catalyst migration and poisoning. Compared with molecular NiPc, the carbon-supported Ni-NC achieves faster sulfur redox kinetics and superior cycling stability. This work identifies catalyst migration as an important degradation pathway in Li-S batteries and proposes a nanostructured design strategy for stable, high-performance electrocatalysts.