A robust, highly reversible, mixed conducting sodium metal anode

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium metal anodes offer high energy density for next-generation batteries.
• Dendrite formation and volume changes during cycling limit sodium metal anode stability.
• Developing robust sodium metal anodes is crucial for sustainable battery technologies.

Purpose of the Study:

• To design a mixed conducting sodium metal anode with enhanced stability and performance.
• To investigate the impact of incorporating a solid sodium-ion conductor into bulk sodium.
• To provide insights into architectural engineering for advanced rechargeable sodium batteries.

Main Methods:

• Incorporation of NaSICON-type solid sodium-ion conductor into bulk sodium metal.
• Fabrication of a composite anode with simultaneous electron and sodium-ion transport pathways.
• Electrochemical testing of symmetric cells and full cells with a Na3V2(PO4)3/C cathode.

Main Results:

• The composite anode establishes a fast, continuous pathway for electrons and sodium ions.
• Intimate contact between phases and compact configuration minimize side reactions and enhance stability.
• Symmetric cells demonstrate over 700 hours of stable cycling at 1 mA cm-2 with 5 mAh cm-2 capacity.
• Outstanding rate capability up to 8 mA cm-2 achieved in carbonate electrolyte.
• Full cells exhibit excellent cycling stability with a low capacity decay of 0.012% per cycle.

Conclusions:

• The designed composite sodium metal anode exhibits highly reversible and durable plating/stripping behavior.
• This architecture engineering strategy provides a robust solution for stable sodium metal anodes.
• The findings pave the way for advanced rechargeable sodium batteries with improved safety and longevity.