Addressing the Low Solubility of a Solid Electrolyte Interphase Stabilizer in an Electrolyte by Composite Battery...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Metallic sodium anodes are promising for sodium-ion batteries due to high capacity and abundance.
• Key challenges include high reactivity, dendrite growth, and poor processability of metallic sodium.
• Metal nitrates are used as electrolyte additives to stabilize the solid electrolyte interphase (SEI), but often have poor solubility.

Purpose of the Study:

• To develop a stable and processable metallic sodium anode for sodium-ion batteries.
• To overcome the limitations of traditional electrolyte additives for sodium anodes.
• To enhance the electrochemical performance and cycling stability of sodium-based batteries.

Main Methods:

• Fabrication of a sodium/sodium nitrate (Na/NaNO3) composite foil via mechanical kneading.
• In-situ reduction of NaNO3 during battery cycling to form a stable SEI.
• Electrochemical testing of Na/NaNO3 symmetric cells and full cells against a Na3V2(PO4)2O2F cathode.

Main Results:

• The Na/NaNO3 composite exhibited uniform embedment of NaNO3 within a metallic Na matrix.
• A stable SEI layer composed of NaNO2 and Na3N species was formed, facilitating fast ion transport.
• Na/NaNO3||Na/NaNO3 symmetric cells achieved stable cycling for 600 hours.
• Na/NaNO3||Na3V2(PO4)2O2F full cells demonstrated stable cycling for 180 cycles, outperforming pure Na anodes.

Conclusions:

• The Na/NaNO3 composite foil offers a viable strategy to improve the stability and performance of metallic sodium anodes.
• Mechanical kneading provides a new method for incorporating anode stabilizers, enhancing battery cycling and processability.
• This approach offers a promising pathway for developing practical and high-performance sodium-ion batteries.