Hybrid Protective Layer for Stable Sodium Metal Anodes at High Utilization

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium metal anodes offer high capacity but suffer from dendrite growth and low efficiency due to unstable solid electrolyte interphases.
• Reactions between sodium metal and organic electrolytes lead to inhomogeneous interphases, hindering battery performance.

Purpose of the Study:

• To develop a protective layer for sodium metal anodes to enhance stability and cycle life.
• To investigate the synergistic effects of an inorganic-organic hybrid coating on sodium anode performance.

Main Methods:

• Constructed a sodium fluoride (NaF)-poly(vinylidene difluoride) (PVDF) hybrid protective layer on a copper current collector using blade-coating.
• Evaluated the protective layer's performance in sodium batteries under various current densities and depths of discharge.

Main Results:

• The NaF-PVDF layer significantly suppressed dendrite initiation and growth, improving Na+ diffusion and mechanical strength.
• Achieved an extended cycle life of over 2100 hours at 1 mA cm⁻² and 50% DOD, a tenfold improvement over bare copper.
• Demonstrated good cycling stability at 5 mA cm⁻² and 80% DOD.

Conclusions:

• The NaF-PVDF hybrid protective layer provides a robust and effective strategy for realizing stable and high-performance sodium metal batteries.
• This rational design of hybrid protective layers opens new avenues for advanced sodium battery development.