Sodium halide-based solid-state electrolyte, method for manufacturing the same, and all-solid-state battery comprising the same

Sodium solid-state electrolyte with improved atmospheric stability and ionic conductivity using +4 transition metals

This technology features a sodium halide-based solid-state electrolyte with a NaaM1bM2cX6 structure, combining sodium (Na), +4 transition metals (M1) such as Ti, Zr, or Hf, and halogen elements (X) to achieve both high sodium-ion conductivity and atmospheric stability.

Conventional sulfide-based solid-state electrolytes suffer from low atmospheric stability, complicating manufacturing, while oxide-based electrolytes face issues with low ionic conductivity. Furthermore, halide-based electrolytes that utilize expensive elements like indium (In) are limited in terms of cost-effectiveness.

This technology synthesizes sodium halide-based compounds—incorporating abundant and affordable +4 transition metals like Zr—via mechanical milling-based solid-state mixing or organic solvent processes. Ionic conductivity can be further enhanced by doping with +2 or +3 metals (M2) such as Y or Fe. Applicable to sodium all-solid-state batteries aimed at reducing lithium dependency, large-scale stationary energy storage systems, and low-cost mass production lines, it offers a solution that reduces dry-room requirements while lowering raw material costs.

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Key Features:

• Sodium halide-based solid-state electrolyte represented by the chemical formula NaaM1bM2cX6, where M1 is a +4 oxidation state transition metal and X is a halogen element
• A +4 transition metal element selected from the group consisting of Ti, Zr, and Hf, occupying the M1 position in the chemical formula
• Step of preparing a Na2M1X6 compound by reacting sodium halide and M1 metal halide precursors through a solid-state mixing method
• Solid-state electrolyte layer for an all-solid-state battery, formed between the cathode and anode layers and containing the sodium halide-based solid-state electrolyte

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This invention was developed with support from the Ministry of Science and ICT for the development of core technologies for R2R-type high-ionic-conductivity functional solid-state electrolyte membranes.

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