Sodium Dual-Ion Batteries with Concentrated Electrolytes

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Sodium-based dual-ion batteries (DIBs) are promising post-lithium energy storage systems.
• Key advantages include fast charging, cost-effectiveness, and abundant sodium resources.
• Electrolyte decomposition at high operating voltages (≈5.0 V) limits DIB performance and lifespan.

Purpose of the Study:

• To investigate the performance of Na-DIBs using various electrolyte systems.
• To optimize a novel electrolyte formulation for enhanced Na-DIB performance.
• To address the critical issue of electrolyte decomposition and capacity fade in Na-DIBs.

Main Methods:

• Evaluation of Na-DIB performance across different standard electrolyte formulations.
• Development and optimization of a highly concentrated (3 m) sodium hexafluorophosphate (NaPF6) electrolyte.
• Incorporation of fluorine-rich components into the carbonate-based electrolyte.
• Performance comparison based on energy density and power density in coin cell configurations, considering only active materials.

Main Results:

• The optimized electrolyte demonstrated improved performance compared to conventional systems.
• The concentrated and fluorine-rich formulation mitigated electrolyte decomposition at high voltages.
• Enhanced energy and power density were achieved, showing potential for practical applications.

Conclusions:

• A highly concentrated, fluorine-rich carbonate-based electrolyte significantly enhances Na-DIB performance.
• This optimized electrolyte addresses the critical challenge of electrolyte decomposition and capacity fade.
• The findings pave the way for more stable and efficient sodium-based dual-ion batteries.