Separator for electrochemical devices and manufacturing method thereof

Electrochemical device separator with sequential hydrophilic and hydrophobic polymer coatings on a paper substrate

This technology is a separator for electrochemical devices that improves electrolyte wettability and ion conductivity while maintaining the mechanical properties and porosity of the paper. It is achieved by forming a composite thin film through the sequential coating of hydrophilic or hydrophobic polymers onto the surface of a porous paper substrate made of cellulose fibers.

Conventional PP/PE separators have limited ion mobility due to low electrolyte wettability caused by their hydrophobic nature. Furthermore, the surfactant treatment methods used to overcome this have limitations in versatility when applied to various electrolytes.

This technology offers a differentiated technical advantage in the secondary battery electrolyte market. It forms a multi-layered composite thin film by either sequentially coating an amine-containing polymer (first layer) and a carboxyl-containing polymer (second layer) onto the cellulose fibers followed by heat treatment to form amide bonds, or by utilizing electrostatic attraction between oppositely charged fluorinated polymers for self-assembled coating.

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Key Features:

• A porous paper substrate made of cellulose fibers and a first polymer layer containing a first polymer disposed on the outer surface of the fibers
• A separator comprising a second polymer layer disposed on the outer surface of the first polymer layer and containing a second polymer
• A configuration where the first and second polymers consist of hydrophilic or hydrophobic polymers and are coated sequentially
• A composite thin-film separator that secures electrolyte wettability while maintaining the mechanical properties and porosity of the paper

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