Method for uniformly coating solid electrolyte films onto the surface of electrode active material particles

Wet coating process for solid electrolyte thin films on active material surfaces using 4–6° low-contact-angle coating solutions

This technology is a wet coating process that forms thin, uniform solid electrolyte coating films by controlling the average contact angle between the electrode active material surface and the solid electrolyte coating solution to 4–6°.

In all-solid-state batteries, poor contact between the electrode active material and the solid electrolyte often leads to high interfacial resistance and degraded cell performance. Even with wet coating attempts, side reactions with solvents have historically limited the ionic conductivity of the solid electrolyte.

This technology uses a dialkyl ether dispersant added to protic polar solvents like water or alcohol to lower the contact angle. By completing the process from coating solution preparation to active material mixing within 5 minutes, it suppresses side reactions while forming a solid electrolyte coating on the active material. Applicable to sulfide-based all-solid-state battery cathode composite manufacturing and sodium-based solid electrolyte coated active material production, it allows for dense interfacial coverage using only 1–8 parts by weight of electrolyte.

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Key Features:

• Step 1: Preparing a solid electrolyte coating solution by dissolving the solid electrolyte in a mixture of solvent and dispersant
• Step 2: Preparing a mixture by combining the prepared solid electrolyte coating solution with electrode active material particles
• Step 3: Removing the solvent from the mixture to form a solid electrolyte coating film on the surface of the electrode active material particles
• A mixture of a protic polar solvent and a dialkyl ether dispersant formulated to exhibit an average contact angle of 4–6° on the surface of electrode active material particles

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This invention was developed with support from the Ministry of Science and ICT for the development of high-performance SOFC cell manufacturing technology using high-functionality gradient-structured composite air electrodes.

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