Band engineering in heterostructure catalysts to achieve High-Performance Lithium-Oxygen batteries

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• The electrochemical kinetics of lithium-oxygen batteries are significantly influenced by the electronic structure of cathode catalysts.
• Conventional catalysts exhibit limited intrinsic activity due to low d-band levels, hindering intermediate bonding and resulting in suboptimal battery performance.

Purpose of the Study:

• To engineer NiFe2O4/MoS2 heterostructures to balance the electronic state of active sites.
• To enhance the d-band level and improve the adsorption of reaction intermediates for superior lithium-oxygen battery performance.

Main Methods:

• Construction of NiFe2O4/MoS2 heterostructures.
• Density Functional Theory (DFT) calculations to analyze the electronic structure and d-band center of active sites.
• Electrochemical testing of lithium-oxygen batteries using the developed catalyst.

Main Results:

• The NiFe2O4/MoS2 heterostructure successfully shifted the d-band level of Fe active sites towards the Fermi level, indicating enhanced electronic properties.
• DFT calculations confirmed electron transfer and balance at the heterointerface, attributing the improved activity to the higher d-band level.
• Lithium-oxygen batteries catalyzed by NiFe2O4/MoS2 demonstrated a high specific capacity (21526 mA h g-1) and extended cycle life (268 cycles).
• The catalyst facilitated uniform discharge product growth and reversible decomposition, crucial for cycling stability.

Conclusions:

• Heterointerface engineering in NiFe2O4/MoS2 catalysts effectively regulates the energy bands of active sites, significantly enhancing catalytic activity.
• The optimized electronic structure and intermediate adsorption properties of the heterostructure are key to improving the performance and cycle stability of lithium-oxygen batteries.