Large Planar Na-β″-Al₂O₃ Solid Electrolytes for Next Generation Na-Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Ceramic Engineering

Background:

• Sodium beta-double-prime alumina (Na-β″-Al₂O₃) is a key solid electrolyte material for sodium-ion batteries.
• Current manufacturing methods for Na-β″-Al₂O₃ often limit scalability and cell design.
• Planar solid electrolytes are desirable for improved cell performance and manufacturability.

Purpose of the Study:

• To develop a scalable method for producing large-diameter, thin planar Na-β″-Al₂O₃ solid electrolytes.
• To evaluate the properties of Na-β″-Al₂O₃ produced via tape casting.
• To assess the potential of planar Na-β″-Al₂O₃ membranes for advanced battery designs.

Main Methods:

• Na-β″-Al₂O₃ was processed into a slurry and tape cast to produce long tapes.
• Large diameter discs (140 mm) were punched, stacked, and laminated using a hydraulic press.
• Binder burnout and sintering were conducted within MgO spinel encapsulations to prevent Na₂O volatilization.

Main Results:

• Successfully prepared large diameter (> 100 mm) planar Na-β″-Al₂O₃ solid electrolytes with thicknesses of 1.0–1.5 mm.
• Electrical conductivity and flexural strength measurements on tape-cast samples were consistent with conventionally produced BASE.
• The tape casting process yielded meters of electrolyte tape, indicating scalability.

Conclusions:

• Tape casting is a viable and scalable method for producing large-diameter, thin planar Na-β″-Al₂O₃ solid electrolytes.
• Planar Na-β″-Al₂O₃ membranes enable novel cell designs with predicted higher power densities and improved stacking efficiency.
• This advancement could lead to more efficient and compact sodium-ion battery technologies.