In-situ catalytic mechanism coupling quantum dot effect for achieving high-performance sulfide anode in potassium-ion batteries

The quantum dot FeS2 materials coupled with reduced graphene oxide have been fabricated by the sulfidation of Fe-MOF precursors. The constructed materials possess numerous rapid ion channel and abundant active area derived from the quantum dot structure, delivering the high-active catalysis ability caused by the formed Fe nanoclusters during potassiation/depotassiation process. This strategy can synchronously guarantee rapid ion transmission, reaction reversibility and structure tolerance of FeS2 materials, then expressing a strengthening capability for accommodating K+-ions. [Display omitted] •The quantum dot FeS2 has been fabricated by the sulfidation of Fe-MOF.•Its shortened ion channel enhances the reaction kinetics.•Its absorption and catalysis actions suppress the polysulfide shuttle effect. Though numerous framework structures have been constructed to strengthen the reaction kinetics and durability, the inevitable generation of polysulfide dissolution during conversion-process can cause irreparable destruction to ion-channel and crystal structure integrality, which has become a huge obstacle to the application of metal-sulfide in potassium-ion batteries. Herein, the quantum dot structure with catalytic conversion capability is synchronously introduced into the design of FeS2 anode materials to heighten its K+-storage performance. The constructed quantum dot structure anchored by the graphene with space-confinement effect can shorten the ion diffusion path and enlarge the active area, thus accelerating the K+-ions transmission kinetics and absorption action, respectively. The intermediate phase of formed Fe-nanoclusters possesses high-active catalysis ability, which can effectively suppress the polysulfide shuttle combined with the enhanced absorption effect, fully guaranteeing the structure stability and cycling reversibility. Predictably, the fabricated quantum dot FeS2 can express a prominent advantage in rapid potassiation/depotassiation processes (518.1 mAh g−1, 10 A g−1) and a superior cycling lifespan with gratifying reversible capacity at superhigh rate (177.7 mAh g−1, 9000 cycles, 5 A g−1). Therefore, engineering quantum dot structure with self-induced catalysis action for detrimental polysulfide is an achievable strategy to implement high-performance sulfide anode materials for K-ions accommodation.