With the rapid development of new energy technologies, solid-state batteries and Solid Oxide Fuel Cells (SOFC) are gradually becoming popular technologies in the future energy storage and conversion fields. Among these cutting-edge technologies, the application of zirconium (Zr) plays a crucial role.

Application of Zirconia in Solid-State Battery

Solid-state batteries can significantly improve safety, energy density, and charging efficiency.

Why Zirconia Is Important for Solid-state Battery

As the core of solid-state batteries, there are three mainstream technological pathways for solid electrolytes: polymers, oxides, and sulfides. Oxide electrolytes are the most mature and breakthrough-prone technology in solid-state batteries, and almost all leading solid-state battery companies have adopted this system. Lithium Lanthanum Zirconium Oxide (LLZO) and Lithium Lanthanum Zirconium Titanium Oxide (LLZTO) are two important solid electrolyte materials widely used in solid-state battery technology. They create new potential demands for zirconium oxide (zirconia) products.

LLZO is sintered by mixing lithium hydroxide, lanthanum oxide, and zirconia, with zirconia accounting for about 25% of the mass of LLZO before sintering. Therefore, zirconium oxide plays an important role in oxide solid electrolytes.

What Are the Benefits of Zirconia for Solid-State Battery

zirconium-based oxides, especially zirconium dioxide (ZrO₂), are primarily utilized in solid-state battery electrolytes due to their unique physical and chemical properties.

• High Ionic Conductivity: Zirconia can exhibit excellent oxygen ion conductivity after appropriate stabilization treatments. For example, adding elements such as yttrium, calcium, or magnesium forms partially stabilized zirconia (YSZ, where YSZ represents Yttria-Stabilized Zirconia). This characteristic makes it an ideal candidate for solid-state battery electrolytes because the rapid conduction of ions within the electrolyte is key to achieving efficient energy conversion.

Fig 1. Yttria-stabilized zirconia exhibits ionic conductivity[1]

• Thermal and Chemical Stability: Zirconia has a very high melting point (approximately 2700°C) and good chemical stability. It can withstand the high operating temperatures of solid-state batteries without decomposition or corrosion during operation. This is crucial for maintaining the long-term stability and safety of the battery.
• Mechanical Strength and Flexibility: As a structural material, zirconia offers good mechanical strength and moderate flexibility, which helps improve the overall stability and durability of the battery. This is especially important in maintaining the integrity of the electrolyte layer when subjected to physical deformation or temperature changes.
• Adaptability to Various Battery Systems: Whether it is a solid-state lithium battery or a solid-state sodium battery, zirconia-based electrolytes can play a significant role. In solid-state lithium batteries, it can act as a medium to isolate the positive and negative electrodes and conduct lithium ions; in solid-state sodium batteries, it serves as a conduction path for sodium ions. This indicates its broad application prospects in different types of solid-state battery systems.
• Environmental Friendliness: Compared to some liquid electrolytes, solid electrolytes like zirconium dioxide reduce the use of volatile and flammable organic solvents, enhancing the safety and environmental compatibility of the battery.

Application of Zirconium in Solid Oxide Fuel Cells (SOFC)

In addition to solid-state batteries, zirconium also plays a key role in Solid Oxide Fuel Cells (SOFC).

Fig 2. Scheme of a solid-oxide fuel cell, Image by: Wikipedia

Solid Oxide Fuel Cells (SOFC) are highly efficient and environmentally friendly electrochemical devices. They directly convert fuel (such as hydrogen, natural gas, or biofuel) and oxidants (usually oxygen from the air) into electrical energy. SOFCs, with their high efficiency and environmental benefits, are important development directions in the future energy conversion field.

The electrolyte powder of SOFC is mainly zirconia, accounting for more than 90% of its mass. The excellent ionic conductivity and stability of zirconia-based electrolytes provide a solid guarantee for the efficient operation of SOFCs. Commonly stabilized zirconia includes:

• Yttria-Stabilized Zirconia (YSZ): Doped with a small amount of yttria (Y₂O₃) to improve its ionic conductivity.
• Other Rare Earth-Stabilized Zirconia: Such as ytterbia (Yb₂O₃) and ceria (CeO₂)-doped zirconia.

Stanford Advanced Materials (SAM) provides not only high purity  zirconium dioxide powder (99.9%) but also a wide range of stabilized zirconia, such as ZrO2-56Y2O3, ZrO2 24CeO2 2.5Y2O3, ZrO2 38Y2O3, and so on. Interested welcome to Get A Quote for more information.

Conclusion

Zirconia, more precisely zirconium dioxide (ZrO₂), is an important material in solid-state batteries and Solid Oxide Fuel Cells (SOFC) because it exhibits high ionic conductivity combined with thermal and chemical stability, mechanical strength, and environmental friendliness. As the demand for sustainable and high-efficiency energy storage and conversion technologies continuously grows, so does the significance of zirconia-based materials. Ongoing innovation in material science and engineering will continue to optimize zirconia's performance, reduce costs, and enhance compatibility with other materials. This will not only enhance the commercial viability of solid-state batteries and SOFCs but also contribute to the development of widespread implementation of clean energy technologies, supporting global endeavors toward a sustainable energy future.