This technology involves dissolving powder, obtained by mechanically milling sulfide-based solid electrolyte raw materials, into a solvent with a polarity index of 4–6. The resulting solution is coated onto an electrode structure and heat-treated to ensure crystallinity. It features an argyrodite structure where a portion of the P-site is substituted with Ge or Sn, and the halogen element is limited to iodine (I) to enhance ionic conductivity.
Conventional sulfide-based solid electrolytes have lower ionic conductivity than organic liquid electrolytes, and their conductivity tends to drop further when subjected to wet solution processing. This has limited their application in all-solid-state battery systems.
This technology adopts a Li-P-Ge-S-I composition to adjust lattice size and induce anion disorder. By applying a coating solution—prepared by dissolving the milled reaction product in a solvent with a polarity index of 4–6—to an electrode, followed by drying at 50–180°C and heat treatment at 300–700°C, the crystallinity of the coating layer is increased by over 20% compared to its post-drying state, achieving a lithium-ion conductivity of 2×10^-4 S/cm or higher. It can be applied to the manufacturing of composite cathodes and anodes for all-solid-state batteries and to roll-to-roll large-area electrode coating lines, allowing the solid electrolyte to penetrate deep into the pores of the active material for tighter interfacial contact.
This invention was developed with support from the Ministry of Trade, Industry and Energy for the development of inorganic solid electrolyte material technology for high-safety energy storage devices, aimed at realizing 0.8mS/cm-class high-ion-conductive membranes and large-area cells.
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