Thin Polypropylene Battery Separator with Heat-Resistant Resin Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current battery separators face challenges in achieving a balance between low curling properties, adhesion of the heat-resistant resin layer, and minimal air resistance increase, especially as they become thinner and the battery assembly process speeds up, which affects battery capacity and safety.
Innovation Solution
A battery separator comprising a polypropylene porous membrane with a thickness of less than 10 μm, laminated with a heat-resistant resin layer and inorganic or cross-linked polymer particles, formed through a process involving specific humidity zones to ensure strong adhesion and controlled air resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the separator membrane is made thinner 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 heat resistant resin layer is applied to the porous membrane before the membrane is deformed during battery assembly. This preliminary application ensures that the resin layer is already in place and can withstand subsequent deformation without peeling, thus maintaining reliability while enabling thinner membrane design for increased battery capacity.
Solution Approach 2:
The invention uses a composite structure consisting of a porous membrane (polypropylene or polyethylene) combined with a heat resistant resin layer (such as polyamide-imide, polyimide, or polyvinylidene fluoride). This composite material provides both the thinness needed for increased battery capacity and the heat resistance and structural stability needed to prevent deformation and peeling during processing.
2Temperature
If a heat resistant resin layer is applied to the porous membrane, then heat resistance improves, but adhesion is insufficient and the resin layer peels off during high-speed processing
Solution Approach 1:
The invention optimizes several parameters to improve adhesion: (1) controls the thickness of the heat resistant resin layer within specific ranges, (2) adjusts the porosity of the porous membrane, (3) selects appropriate resin materials with compatible properties, and (4) controls the thickness ratio between the heat resistant resin layer and the porous membrane. These parameter changes ensure sufficient adhesion strength to withstand high-speed processing while maintaining heat resistance.
3Strength
If the heat resistant resin layer is made thicker to improve adhesion, then adhesion strength increases, but air resistance increases significantly
Solution Approach 1:
The invention precisely controls the thickness of the heat resistant resin layer within specific ranges (e.g., 1-10 μm depending on the embodiment) to achieve the optimal balance between adhesion strength and air resistance. This parameter optimization ensures that the resin layer is thick enough to provide sufficient adhesion for high-speed processing while remaining thin enough to minimize air resistance and maintain ion permeability for battery performance.
4Ease of manufacture
If conventional coating methods are used to apply heat resistant resin, then the process is simple, but curling is large and adhesion is insufficient
Solution Approach 1:
The invention controls specific parameters during the coating process including: (1) the thickness of the applied heat resistant resin layer, (2) the porosity of the porous membrane substrate, (3) the composition and concentration of the resin solution, and (4) the drying conditions. These parameter controls enable conventional coating methods to produce separators with minimal curling and sufficient adhesion, maintaining manufacturing simplicity while improving manufacturing precision.
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, enhancing heat resistance, ion permeability, and processability in high-speed battery assembly processes, ensuring safety and increased battery capacity.
Implementation Method 1
a battery separator comprising a heat resistant resin layer and a polypropylene porous membrane
Implementation Method 2
having ion permeability due to electrolyte impregnation
Data Source
AI summary
A battery separator includes a porous membrane A with a thickness of less than 10 μm including a polypropylene 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 a specific range of thickness, average pore size, and porosity, and the entire battery separator satisfies a specific range of thickness, peeling strength at the interface between the porous membrane A and the porous membrane B, and difference in air resistance between the entire battery separator and the porous membrane A.