Separator for lithium secondary batteries using inorganic liquid electrolytes

Separator with hydrophilic polymer double-sided coating for enhanced wettability of SO2-based inorganic electrolytes

This technology is a separator for lithium secondary batteries that improves electrolyte wettability by coating both sides of a porous separator with a hydrophilic polymer, such as polyethylene oxide (PEO), to a specific thickness, thereby increasing affinity with sulfur dioxide (SO2)-based inorganic liquid electrolytes.

Conventional polyolefin separators suffer from low wettability with SO2-based inorganic liquid electrolytes, leading to insufficient impregnation, which results in degraded battery performance and shortened cycle life.

This technology is configured to improve charge/discharge efficiency and low-temperature operational stability by coating both sides of a porous substrate, such as polyethylene, with a polymer material like PEO at a thickness of 1–10 μm, optimizing wettability for inorganic liquid electrolytes. It can be applied to high-safety lithium secondary batteries using non-flammable inorganic electrolytes, power sources for equipment in polar or high-altitude regions, and special-purpose energy storage devices, ensuring stable operation without electrolyte impregnation issues even in sub-zero environments.

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Key Features:

• Separator used with inorganic liquid electrolytes containing lithium salts such as LiAlCl4 injected with sulfur dioxide
• Coating layer formed on both sides of the separator with polymer materials such as polyethylene oxide or polyvinylpyrrolidone at a thickness of 1–10 μm
• Porous substrate made of one or more materials selected from polyethylene, polypropylene, polyimide, etc.
• Electrode assembly in which a coated porous separator is placed between the cathode and anode and combined with LiAlCl4-3SO2 electrolyte

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This invention was developed with support from the Ministry of Trade, Industry and Energy for intelligent battery control for distributed solar power and energy storage systems.

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