Thin Battery Separator with Heat-Resistant Resin Layer
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Solution Overview
Problem
Existing battery separators face challenges with thinning membranes, leading to issues such as peeling of the heat-resistant resin layer, increased air resistance, and reduced safety and productivity during high-speed battery assembly processes, while maintaining ion permeability and heat resistance.
Innovation Solution
A battery separator comprising a polyethylene porous membrane with a thickness of less than 10 μm, laminated with a heat-resistant resin layer and inorganic particles or cross-linked polymer particles, formed through a process involving low and high humidity zones to achieve strong adhesion and controlled air resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the polyethylene porous membrane thickness is reduced to less than 10 μm to increase battery capacity, then the area for electrodes and separator that can be loaded into the container increases, but the membrane becomes deformed in the planar direction and the heat resistant resin layer peels off during processing
Solution Approach 1:
The patent uses a composite structure consisting of a polyethylene porous membrane (thickness <10 μm) combined with a heat resistant resin layer containing cross-linked polymer particles. This composite material approach allows the thin membrane to maintain its structural integrity and resistance to planar deformation while preserving the battery capacity benefits of reduced thickness.
Solution Approach 2:
The patent introduces cross-linked polymer particles specifically into the heat resistant resin layer to provide localized reinforcement. This local quality enhancement at the resin layer level prevents membrane deformation and peeling without requiring overall thickening of the entire separator structure.
2Temperature
If a heat resistant resin layer is applied to the polyethylene porous membrane to improve heat resistance, then heat resistance and oxidation resistance are enhanced, but air resistance increases significantly and pore-blocking function decreases
Solution Approach 1:
The patent employs a porous heat resistant resin layer containing cross-linked polymer particles that maintain porosity and pore structure. This porous structure allows the resin layer to provide heat resistance while minimizing air resistance increase and preserving the pore-blocking function of the separator.
Solution Approach 2:
The combination of polyethylene porous membrane with heat resistant resin and cross-linked polymer particles creates a composite structure where the resin layer provides thermal stability without significantly blocking pores or increasing air resistance, as the cross-linked particles maintain structural openness.
3Ease of manufacture
If the heat resistant resin layer is applied using conventional coating methods (roll coating, die coating, bar coating, blade coating), then the resin component infiltrates into the polyolefin porous membrane, but this causes significant increase in air resistance and decrease in pore-blocking function
Solution Approach 1:
The patent extracts the harmful infiltration effect by using a coating method that prevents resin component penetration into the polyolefin pores. The cross-linked polymer particles in the resin layer act as barriers that stop infiltration, thereby maintaining low air resistance and preserving pore-blocking function while still achieving heat resistance.
4Ease of manufacture
If conventional coating methods are used to apply the heat resistant resin, then the coating process is simple, but unevenness of the polyolefin porous membrane leads to unevenness of the heat resistant resin layer, resulting in variation in air resistance
Solution Approach 1:
The patent uses cross-linked polymer particles distributed in the heat resistant resin layer to create local quality enhancement. These particles provide anchoring points that ensure uniform resin layer formation even on uneven polyolefin surfaces, reducing variation in air resistance while maintaining simple coating processes.
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 provides excellent adhesion of the heat-resistant resin layer with minimal air resistance increase, ensuring high ion permeability, heat resistance, and low curling properties, enhancing the safety and productivity of battery assembly processes.
Implementation Method 1
a battery separator comprising a heat resistant resin layer and a polyethylene porous membrane
Implementation Method 2
having ion permeability due to electrolyte impregnation
Implementation Method 3
having such a pore-blocking effect that excessive temperature rise is suppressed by blocking a current at a temperature of about 120 to 150° C.
Implementation Method 4
a porous membrane B laminated thereon comprising a heat resistant resin and inorganic particles or cross-linked polymer particles
Data Source
AI summary
A battery separator includes a porous membrane A including a polyethylene resin, and a porous membrane B laminated thereon including a heat resistant resin and inorganic particles or cross-linked polymer particles, wherein the porous membrane A satisfies expressions (a) to (c), and the entire battery separator satisfies expressions (d) to (f).