Bimetallic Alloy Air Cathode Promoting Superoxide Formation for High-Performance Na-Air Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Sodium superoxide is the preferred discharge product for sodium-air batteries (SABs) due to its reversible electrochemistry and low charge overpotential.
• Existing mono-metal systems struggle with optimal discharge product adsorption, limiting SAB performance.

Purpose of the Study:

• To develop an advanced air cathode for SABs using a bimetallic alloy strategy.
• To investigate the impact of FeCo bimetallic alloy particles on carbon nanotubes (FeCo/C) on SAB performance.

Main Methods:

• Fabrication of FeCo bimetallic alloy nanoparticles anchored on carbon nanotubes (FeCo/C).
• Electrochemical testing of SABs with FeCo/C air cathodes, including charge/discharge cycling and overpotential measurements.
• Ex-situ spectroscopy to analyze discharge product composition.
• Theoretical calculations to understand adsorption mechanisms.

Main Results:

• SABs with FeCo/C cathodes achieved a low overpotential gap (500 mV) and high discharge capacity (3392.20 mAh g⁻¹).
• Excellent cyclic stability was observed over 200 cycles (800 h).
• Ex-situ spectroscopy confirmed sodium superoxide as the primary discharge product, correlating with enhanced performance.

Conclusions:

• FeCo bimetallic alloy cathodes effectively optimize sodium superoxide adsorption in SABs.
• The bimetallic alloy strategy significantly enhances SAB performance and cyclic stability.
• This work demonstrates a promising approach for advancing SAB technology towards practical applications.