Solid electrolyte and method for manufacturing the same

High-ion-conductivity solid electrolyte using a thiophenium-fluorohydrogenate crystalline phase doped with lithium salt

This technology involves an electrolyte design that creates a crystalline solid electrolyte by combining a thiophenium-based cation with a fluorohydrogenate-based anion, then doping it with lithium salt to maximize lithium-ion mobility through interstitial sites in an orthorhombic crystal structure.

Conventional liquid electrolytes suffer from issues such as leakage, volatility, thermal instability, and explosion risks. Conversely, typical solid electrolytes have faced limitations in practical application due to low ionic conductivity.

This technology produces a compound combining thiophenium and fluorohydrogenate, places lithium salt in the interstitial sites of the orthorhombic crystal structure, and controls the compound's melting entropy to 15–25 J/K·mol to ensure flexibility within the crystalline phase, achieving ionic conductivity of over 200 mS/cm at room temperature. Its strength lies in enabling liquid-level conductivity in a solid state, making it suitable for leak-free, high-safety lithium secondary batteries and small cells for wearable devices.

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Key Features:

• A solid electrolyte composed of a compound combining a thiophenium-containing cation and a fluorohydrogenate-containing anion
• An alkyl group bonded to the sulfur atom of the thiophenium, selected from a methyl, ethyl, propyl, or butyl group
• An orthorhombic unit cell with cations at the vertices and face centers, anions at the edge centers, and lithium salt provided in interstitial sites
• A step of preparing the compound by reacting a mixed solution of thiophenium salt and a fluorohydrogenate precursor at a temperature below room temperature

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This invention was developed with support from the Ministry of Science and ICT for the development of a high-energy-density soft materials platform through the design of new organic superionic plastic crystal materials.

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