In-situ engineered ZnS-FeS heterostructures in N-doping carbon nanocages accelerating polysulfides redox kinetics for lithium sulfur batteries
The electrode materials with efficient catalyzing capability for polysulfides in lithium sulfur batteries are currently receiving intensive research for next-generation portable electronic equipment. Herein, a novel hollow architecture composed of ZnS-FeS heterostructures encapsulated in N-doping carbon is designed firstly as a high-efficiency catalyst to propel the polysulfides redox kinetics, in which the ZnS-FeS heterostructures are mosaiced in the carbon framework through a simple in-situ sulfuration process. Kinetics analyses and theoretical calculation verify that the abundant heterojunction could facilitated electron and ion transfer, strengthen the combination with polysulfides and boosted the polysulfides redox reaction kinetics. Ex-situ electrochemical impedance spectral (EIS) revealed that the excellent interface solid-liquid-solid conversion reaction. Benefiting from the state-of-the-art design, the S@ZnS-FeS@NC electrode shows an outstanding rate capacity (718 mAh g-1 at 4.0 C) and favorable cycling stability (822 mAh g-1 at 0.2 C after 200 cycles). Our approach would be a proof-of-concept design of metal sulfide heterojunction as effective sulfur host in improving the polysulfides redox kinetics for lithium sulfur batteries.