Journal
ADVANCED FUNCTIONAL MATERIALS
Volume 32, Issue 14, Pages -Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/adfm.202109899
Keywords
core-shell structure; DFT calculations; FeS; (2); polysulfides; potassium-ion batteries
Categories
Funding
- Chinese National Science Fund for Distinguished Young Scholars [52025015]
- National Natural Science Foundation of China [51771130, 51531004, 51422104, 51972227]
- Tianjin Youth Talent Support Program
- Tianjin Natural Science Funds for Distinguished Young [17JCJQJC44300]
- Tianjin Science and Technology Support Project [17ZXCLGX00060]
- China Postdoctoral Science Foundation [2020M670649]
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A graphene-shell-encapsulated FeS2 embedded in N/S codoped 3D hollow carbon spheres is developed to address the issue of polysulfides dissolution in potassium-ion batteries. Experimental and computational results demonstrate that the graphene-shell promotes K ion mobility, enhancing cycle stability and rate performance of the electrode. These findings provide insights for designing metal-based sulfide electrodes for PIBs.
Resource-rich FeS2 is a promising anode for potassium-ion batteries (PIBs). However, polysulfides emerge due to FeS2 conversion during discharging, which dissolve into the ether-based electrolyte and cause the continuous capacity degradation in PIBs. To address the polysulfides dissolution in PIBs, a graphene-shell-encapsulated FeS2 is fabricated and embedded in N/S codoped 3D hollow carbon spheres. As a protective pocket, the graphene-shell can effectively accommodate polysulfides inside the core-shell, inhibiting the polysulfides shuttle effect to enhance cycle stability of electrode. The density functional theory (DFT) calculations demonstrate that graphene-shells have a strong adsorption capacity for polysulfides, and the interfacial interaction between KFeS2 and graphene-shell can boost the K ion mobility. As a result, the composite exhibits superior-rate properties (524 and 224 mA h g(-1) at 0.1 and 8 A g(-1), respectively) and long-term cycle stability. This work demonstrates the promotion and protective effect of the graphene-shell for the FeS2 to storage K from both experimental and computational perspectives. These research outputs can provide guidance for designing other metal-based sulfide electrodes for PIBs.
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