High Coulombic Efficiency Na-O₂ Batteries Enabled by a Bilayer Ionogel/Ionic Liquid

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Sodium-oxygen (Na-O2) cells offer high theoretical specific energy (1605 Wh kg-1).
• Key challenges include achieving high practical energy density and long-term cycling stability.
• Anode side reactions and cathode reaction kinetics limit current performance.

Purpose of the Study:

• To enhance the Coulombic cyclic efficiency of Na-O2 cells.
• To improve the long-term cycling capability of Na-O2 energy storage.
• To address limitations in practical energy density and cell stability.

Main Methods:

• Development and implementation of a novel bilayer electrolyte.
• Utilizing an ionogel in conjunction with an ionic liquid electrolyte.
• Investigating the role of each electrolyte component in cell performance.

Main Results:

• Demonstrated superior Coulombic cyclic efficiency, approaching 100%.
• The ionogel component effectively suppressed detrimental side reactions at the anode.
• The ionic liquid component facilitated high reaction rates at the cathode.

Conclusions:

• The bilayer electrolyte represents a significant advancement for Na-O2 battery technology.
• This approach offers a promising strategy for extending cell cycling life.
• The findings pave the way for higher practical energy densities in Na-O2 storage.