Superconcentration Strategy Allows Sodium Metal Compatibility in Deep Eutectic Solvents for Sodium-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Sustainable Energy

Background:

• Sodium-ion batteries (SIBs) offer a sustainable alternative to lithium-ion batteries (LIBs) due to sodium's abundance and low cost.
• Current SIB development is limited by materials, impacting energy density and safety.
• Deep eutectic solvents (DESs) are promising nonflammable electrolytes for SIBs but face challenges with electrochemical stability.

Purpose of the Study:

• To develop stable and safe electrolytes for sodium-ion batteries.
• To overcome the limited electrochemical stability of conventional DESs.
• To enhance the performance of SIBs using novel DES compositions.

Main Methods:

• A superconcentration strategy was employed to create sodium-ion conducting DESs.
• NaFSI was dissolved in N-methylacetamide to form the DES.
• Electrochemical stability and performance were tested with sodium metal and Prussian blue electrodes at 60 °C.

Main Results:

• The developed DES demonstrated simultaneous stability with sodium metal and Prussian blue electrodes.
• The nonflammable DES exhibited superior rate performance and capacity retention compared to conventional liquid electrolytes at 60 °C.
• The novel DES compositions significantly improve the safety and sustainability of SIBs.

Conclusions:

• Superconcentration of DESs in N-methylacetamide provides a viable route for stable sodium-ion battery electrolytes.
• These findings pave the way for practical applications of DESs in SIBs, enhancing safety and sustainability.
• The developed electrolytes offer improved performance, addressing key limitations in current SIB technology.