Manufacturing method for multilayer microporous membranes

Multilayer microporous membranes with alternating polypropylene and polyethylene layers, manufactured via co-extrusion and stretching, address the need for thinner, stronger battery separators by enhancing strength and performance in lithium-ion batteries.

JP7883530B2Inactive Publication Date: 2026-07-01CELGARD LLC
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Patent Information

Authority / Receiving Office
JP · JP
Patent Type
Patents
Current Assignee / Owner
CELGARD LLC
Filing Date
2024-01-22
Publication Date
2026-07-01
Estimated Expiration
Not applicable · inactive patent

AI Technical Summary

Technical Problem

Conventional single-layer or multi-layer membrane separators, such as the three-layer polyolefin separators, fail to meet the stringent requirements for thinner and stronger battery separators in newer battery designs, particularly lithium-ion rechargeable batteries, due to reduced strength and inadequate performance balance.

Method used

Development of multilayer microporous membranes with alternating layers of polypropylene and polyethylene, manufactured through co-extrusion and lamination, which are then stretched to enhance strength and porosity, incorporating additives for improved properties.

Benefits of technology

The multilayer membranes exhibit enhanced shutdown, dielectric breakdown strength, and reduced splitting tendency, with improved puncture resistance, elasticity, and tensile strength compared to traditional designs.

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Abstract

To provide a method of making a multilayer microporous membrane with improved shutdown, improved strength, and improved dielectric breakdown strength.SOLUTION: A method of making a multilayer microporous membrane comprises: extruding each of a polypropylene precursor comprising a plurality of sublayers, and a polyethylene precursor comprising a plurality of sublayers; laminating the extruded polypropylene and polyethylene precursor layers to produce a first intermediate precursor having a structure with alternating polyethylene and polypropylene precursors; simultaneously or singly laminating a first outer layer comprising one of the extruded polypropylene precursors to a first surface of the intermediate precursor and a second outer layer comprising one of the extruded polypropylene precursors to a second surface of the first intermediate precursor opposite the first surface so as to produce a second intermediate precursor; annealing the second intermediate precursor to produce an annealed multilayer membrane; and uniaxially or biaxially stretching the annealed multilayer membrane to produce a microporous multilayer membrane.SELECTED DRAWING: Figure 1
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