Multilayer Battery Separator Membranes With Low Pin Removal Force
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Solution Overview
Problem
Existing battery separator membranes with polypropylene outer layers often have high pin removal forces, leading to dislodgment issues during the winding process of cylindrical and prismatic batteries, affecting production yields and uniformity.
Innovation Solution
A laminated multilayer microporous membrane with polyethylene exterior layers and polypropylene inner layers, such as a PE/PP/PE configuration, is used to reduce pin removal force, enhance electrolyte absorption, and improve adhesion to coatings, while allowing for tunable thermal shutdown and improved web handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polypropylene is used as the outer layer in a multilayer separator membrane, then the tensile strength and melt temperature are improved, but the pin removal force becomes excessively high causing dislodgment issues during winding
Solution Approach 1:
The separator membrane is divided into multiple layers with distinct functions: the outer polypropylene layers provide mechanical strength and heat resistance, while the inner polyethylene layer provides thermal shutdown protection. This segmentation allows each layer to optimize its specific function without compromising the other properties.
Solution Approach 2:
Different layers of the separator membrane are assigned different material properties tailored to their specific roles. The outer polypropylene layers have high tensile strength and high melt temperature for structural integrity, while the inner polyethylene layer has low melt temperature for thermal shutdown, creating local quality optimization throughout the membrane structure.
2Temperature
If polypropylene is used as the outer layer in a multilayer separator membrane, then the heat resistance is improved, but the pin removal force becomes excessively high affecting production yields
Solution Approach 1:
The separator membrane is divided into multiple layers with distinct functions: the outer polypropylene layers provide mechanical strength and heat resistance, while the inner polyethylene layer provides thermal shutdown protection. This segmentation allows each layer to optimize its specific function without compromising the other properties.
Solution Approach 2:
The separator membrane uses a composite structure combining polypropylene and polyethylene layers. The polypropylene outer layers provide high heat resistance and tensile strength, while the polyethylene inner layer provides thermal shutdown protection and reduced pin removal force, creating a composite material that achieves multiple performance goals simultaneously.
3Strength
If a multilayer configuration with polypropylene outer layers is used, then the mechanical strength is improved, but the web handling performance deteriorates due to high pin removal force
Solution Approach 1:
The separator membrane is divided into multiple layers with distinct functions: the outer polypropylene layers provide mechanical strength and heat resistance, while the inner polyethylene layer provides thermal shutdown protection. This segmentation allows each layer to optimize its specific function without compromising the other properties.
Solution Approach 2:
Different layers of the separator membrane are assigned different material properties tailored to their specific roles. The outer polypropylene layers have high tensile strength and high melt temperature for structural integrity, while the inner polyethylene layer has low melt temperature for thermal shutdown and improved web handling, creating local quality optimization throughout the membrane structure.
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 solution enables optimal battery cell yields, increased electrolyte absorption, improved coating adhesion, and enhanced manufacturing efficiency by reducing pin removal force and allowing wider membrane widths, thus improving the economics of battery production.
Implementation Method 1
battery separator membranes having increased electrolyte absorption capacity at the separator/electrode interface region
Implementation Method 2
low melt temperature polyethylene may be used as the inner, thermal shutdown layer
Data Source
AI summary
Disclosed herein are novel or improved microporous battery separator membranes, separators, batteries including such separators, methods of making such membranes, separators, and/or batteries, and/or methods of using such membranes, separators and/or batteries. Further disclosed are laminated multilayer polyolefin membranes with exterior layers comprising one or more polyethylenes, which exterior layers are designed to provide an exterior surface that has a low pin removal force. Further disclosed are battery separator membranes having increased electrolyte absorption capacity at the separator/electrode interface region, which may improve cycling. Further disclosed are battery separator membranes having improved adhesion to any number of coatings. Also described are battery separator membranes having a tunable thermal shutdown where the onset temperature of thermal shutdown may be raised or lowered and the rate of thermal shutdown may be changed or increased. Also disclosed are multilayer battery separator membranes having enhanced web handling performance during manufacturing processes and coating operations.