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论文类型：期刊论文

发表时间：2019-08-01

发表刊物：SMALL

收录刊物：SCIE、PubMed

卷号：15

期号：34

页面范围：e1902431

ISSN号：1613-6810

关键字：catalytic oxidation; lithium-sulfur batteries; nanoreactors; polysulfide conversion; synergic effects

摘要：Reducing the deposit of discharge products and suppressing the polysulfide shuttle are critical to enhancing reaction kinetics in Li-S batteries. Herein, a Pt@Ni core-shell bimetallic catalyst with a patch-like or complete Ni shell based on a confined catalysis reaction in porous carbon spheres is reported. The Pt nanodots can effectively direct and catalyze in situ reduction of Ni2+ ions to form core-shell catalysts with a seamless interface that facilitates the charge transfer between the two metals. Thus, the bimetallic catalysts offer a synergic effect on catalyzing reactions, which shows dual functions for catalytic oxidation of insoluble polysulfides to soluble polysulfides by effectively reducing the energy barrier with simultaneous strong adsorption, ensuring a high reversible capacity and cycling stability. A novel process based on the Pt@Ni core-shell bimetallic catalyst with a patch-like Ni shell is proposed: electronic migration from Ni to Pt forces Ni to activate Li2S2/Li2S molecules by promoting the transformation of Li-S-Li to Ni-S-Li, consequently releasing Li+ and free electrons, simultaneously enhancing protonic/electronic conductivity. The presence of the intermediate state Ni-S-Li is more active to oxidize Li2S to polysulfides. The Li2S bound to adjacent Pt sites reacts with abundant -S-Li species and then releases the Pt sites for the next round of reactions.