Separator for lithium-ion batteries containing melamine-phenylphosphonic acid, manufacturing method thereof, and lithium-ion battery comprising the same

PI Separator with Macropores Blocked by Doctor Blade Melamine-Phenylphosphonic Acid Coating

This technology coats the surface of a polyimide (PI) separator with melamine-phenylphosphonic acid (MP) to close the inherent macropores of the PI separator, thereby improving both electrochemical performance and mechanical properties.

While conventional polyimide (PI) separators offer excellent thermal stability, their macroporous structure has historically caused internal short circuits and current leakage during cell assembly and charging, limiting their practical application in batteries.

This technology involves dispersing melamine-phenylphosphonic acid into a slurry containing a PVdF-HFP binder and applying it to the PI separator surface via doctor blade coating to effectively block pores. The coating layer improves electrolyte wettability and absorption, enhances mechanical strength to prevent internal shorts, and ensures stable cycle performance. It is suitable for mid-to-large lithium-ion batteries using NCM811 cathodes and industrial batteries requiring high-temperature operation, lowering the barrier to commercialization for heat-resistant PI separators.

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Key Features:

• Preparing a melamine-phenylphosphonic acid-containing slurry by dispersing melamine-phenylphosphonic acid in a solution containing a binder and a solvent
• Coating the melamine-phenylphosphonic acid onto the surface of a polyimide-based separator by casting the slurry onto the separator using a doctor blade
• Melamine-phenylphosphonic acid dispersed in the slurry at a content of 2.5 wt% or more relative to 100 wt% of the binder
• A polyimide separator coated with melamine-phenylphosphonic acid using a slurry containing PVdF-HFP as a binder and N-methyl-2-pyrrolidone as a solvent

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