Enflurane Additive for Sodium Negative Electrodes.

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Sodium anodes (hard carbon and metallic) require stable electrolytes for efficient Na+ transport and interphase stabilization.
• Halogen salt additives improve sodium plating/stripping but can be complex.
• Developing simple, effective electrolyte additives is crucial for advanced sodium-ion batteries.

Purpose of the Study:

• To introduce enflurane as a novel, halogen-rich molecular additive for sodium-ion battery electrolytes.
• To evaluate enflurane's impact on the stability and performance of hard carbon and metallic sodium anodes.
• To investigate the mechanism of enflurane's action at the electrode-electrolyte interface.

Main Methods:

• Electrochemical testing of symmetric cells and half-cells with enflurane additive.
• Analysis of the solid electrolyte interphase (SEI) composition and structure.
• Comparison of cycling performance with and without enflurane.

Main Results:

• Enflurane is preferentially reduced at hard carbon electrodes, forming a stable, halogen-rich SEI.
• The enflurane-derived SEI enhances Na+ transport and cycling stability.
• Enflurane effectively suppresses polarization in metallic sodium electrodes.
• Hard carbon half-cells with 10% enflurane show improved reversible capacity and stability.

Conclusions:

• Enflurane serves as a simple yet effective molecular additive for sodium-ion battery electrolytes.
• It significantly improves the performance and stability of both hard carbon and metallic sodium anodes.
• The formation of a tailored, halogen-rich SEI is key to enflurane's beneficial effects.