Scalable Dry Process for Fabricating a Na Superionic Conductor-Type Solid Electrolyte Sheet.

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Commercialization of all-solid-state batteries hinges on cost-effective mass production of solid electrolytes.
• Current methods for oxide-based solid electrolytes often involve solvents and limit the concentration of the active material.

Purpose of the Study:

• To develop an environmentally friendly, solvent-free dry process for fabricating high-density, flexible oxide-based sodium superionic conductor solid electrolyte sheets.
• To investigate the impact of binder content and particle size on the properties of the solid electrolyte sheets produced via the dry process.

Main Methods:

• Fabrication of a solid electrolyte sheet using a novel dry process, avoiding solvents.
• Utilizing polytetrafluoroethylene (PTFE) as a binder, transformed into thread-like structures via shear force for flexibility.
• Optimizing the dry process to increase the solid electrolyte powder content to over 95 wt% in the green sheets.
• Investigating the effect of binder content (specifically 3 wt% PTFE) and finely ground solid electrolyte powder on ionic conductivity.

Main Results:

• The dry process enabled fabrication of green sheets with significantly higher density compared to traditional wet processes.
• The dry process allowed for a solid electrolyte powder content exceeding 95 wt%, compared to a 50 wt% limit in wet processes.
• The optimized solid electrolyte sheet (3 wt% PTFE binder, finely ground powder) exhibited the highest total ionic conductivity, reaching 1.03 mS cm^-1.

Conclusions:

• A solvent-free dry process is effective for producing high-density, flexible oxide-based solid electrolyte sheets.
• This method significantly increases the solid electrolyte content and improves density, crucial for battery performance.
• The optimized material demonstrates promising ionic conductivity for applications in all-solid-state batteries.