Coated Battery Separator Membranes With Built-In Adhesion Promotion
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Solution Overview
Problem
Existing battery separators face challenges in achieving strong adhesion between polypropylene-containing layers and polyaramid-based coatings without requiring additional processing steps.
Innovation Solution
Incorporating functionalized polymers, such as maleic anhydride modified polyolefins, as additives in microporous membranes to enhance adhesion with polyaramid-containing coatings and metallic surfaces, improving properties like adhesion, durability, and ion capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polypropylene-containing layers are used in battery separators, then oxidation resistance and cycling performance are improved, but adhesion to polyaramid-based coatings deteriorates
Solution Approach 1:
The patent applies local quality by incorporating maleic anhydride modified polyolefin specifically at the interface between the polypropylene layer and the polyaramid coating. This localized modification creates a region with enhanced polar character and adhesion properties without altering the bulk polypropylene material that provides oxidation resistance. The functionalized polymer acts as an interfacial layer that bridges the non-polar polypropylene and polar polyaramid coating.
Solution Approach 2:
The patent employs composite materials by creating a multi-component system consisting of polypropylene, maleic anhydride modified polyolefin, and polyaramid coating. The functionalized polymer serves as a compatibilizer that combines the benefits of polypropylene (oxidation resistance) with improved adhesion to the polyaramid coating. This composite approach allows the separator to simultaneously achieve both oxidation resistance and strong coating adhesion.
2Strength
If additional surface treatment steps are performed to improve adhesion, then adhesion strength is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-functionalizing the polyolefin with maleic anhydride groups before the coating process. This pre-modification ensures that the polypropylene layer has inherent adhesion capability to polyaramid coatings from the outset, eliminating the need for subsequent surface treatment steps such as plasma treatment, corona discharge, or chemical etching. The functionalized polymer is incorporated during the extrusion process, making adhesion improvement an intrinsic property of the separator material.
Solution Approach 2:
The patent merges the adhesion enhancement function with the separator manufacturing process itself. By incorporating maleic anhydride modified polyolefin during the extrusion of the polypropylene layer, the adhesion-promoting functionality is integrated into the base material production. This combines what would traditionally be separate steps (separator manufacturing and surface treatment) into a single unified process, reducing overall manufacturing complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The additive-enhanced membranes exhibit improved adhesion and durability, reducing pin removal force, and enhancing wetting and ion capture, thereby improving the performance of battery separators.
Implementation Method 1
The additive may comprise at least one material that improves adhesion of the microporous membrane to a coating, preferably a polyaramid-containing coating
Implementation Method 2
In some embodiments, the functional group of the functionalized polymer may be maleic anhydride (MAH)
Data Source
AI summary
A new or improved microporous monolayer, bilayer, trilayer, or multilayer membrane, separator membrane, separator, or coated separator is disclosed. The membrane is preferably made up of at least one resin or polymer and at least one additive. The additive may comprise at least one material that improves adhesion of the microporous membrane to a coating, including a polyaramid-containing coating and a PCS coating, or to a different material such as a metallic surface, including an electrode surface. Improvements in adhesion are based on comparisons to similar microporous membranes without the at least one additive. In some preferred embodiments, the at least one additive may comprise, consist of, or consist essentially of a functionalized polymer or the combination of a functionalized polymer and an elastomer. In some embodiments, the functional group of the functionalized polymer may be maleic anhydride (MAH). Also disclosed is a battery separator or coated separator comprising the new or improved microporous membrane. The battery separator may comprise the microporous membrane coated with a polyaramid-containing coating. Also disclosed is a new or improved separator, composite, battery, secondary lithium ion battery, and/or vehicle or device comprising the separator, composite, or battery.