Battery Separator with Pressurized Resin Surface Layer
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Solution Overview
Problem
Laminated microporous films with non-woven fabric bases face issues with pin hole generation and uneven thickness, leading to safety concerns and reduced mechanical characteristics, which are not adequately addressed by existing solutions.
Innovation Solution
A laminated microporous film with a non-woven fabric base and a surface layer containing a resin material and inorganic particles, where the surface layer is formed through a pressurizing process to bury pin holes and achieve uniform thickness, enhancing mechanical and heat resistance properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a non-woven fabric is used as a microporous film base, then cost is reduced and heat resistance is improved, but pin holes are generated irregularly and thickness becomes uneven
Solution Approach 1:
The patent applies a preliminary action by forming a resin layer on the non-woven fabric base before final assembly. This resin layer serves to fill and cover the pin holes and uneven surfaces that inherently exist in non-woven fabrics, thereby preventing these defects from affecting the final product quality while maintaining the cost advantages of using non-woven fabric.
Solution Approach 2:
The patent creates a composite structure by combining non-woven fabric with a resin layer containing inorganic particles. This composite material approach allows the non-woven fabric to provide heat resistance and cost advantages, while the resin layer compensates for the pin hole and thickness uniformity issues, achieving both economic and quality objectives.
2Reliability
If the amount of lamination of microfibers is increased to minimize pin holes, then pin hole generation is reduced, but separator thickness increases
Solution Approach 1:
The patent extracts the pin hole prevention function from the bulk structure of the non-woven fabric and concentrates it in a surface resin layer. Instead of increasing the overall thickness of microfibers to eliminate pin holes, the resin layer is applied specifically at the surface where pin holes would cause problems, thereby preventing pin holes without increasing overall separator thickness.
Solution Approach 2:
The patent applies local quality by concentrating the pin hole prevention capability in a localized resin layer at the surface of the non-woven fabric, rather than uniformly increasing the thickness throughout the entire separator. This allows pin hole prevention to be achieved in the critical surface region without unnecessarily increasing overall thickness.
3Reliability
If polyethylene resin is used for shutdown function, then safety at lower temperatures is ensured, but heat resistance at higher temperatures is insufficient
Solution Approach 1:
The patent merges two different functional materials: polyethylene resin for shutdown function and non-woven fabric (with higher melting point) for heat resistance. The polyethylene layer provides the shutdown safety by melting at lower temperatures to close pores, while the non-woven fabric base maintains structural integrity at higher temperatures, thus combining both safety and heat resistance in a single separator structure.
Solution Approach 2:
The patent creates a composite separator structure where polyethylene resin and non-woven fabric work together. The polyethylene component ensures shutdown safety at lower temperatures, while the non-woven fabric component provides heat resistance at higher temperatures, achieving both temperature-dependent safety requirements through material composition rather than contradiction.
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 effectively prevents pin hole generation, achieves uniform film thickness, and improves mechanical characteristics, ensuring high safety and performance as a battery separator for applications in electric power tools, electric vehicles, and hybrid cars.
Implementation Method 1
a surface layer, which includes inorganic particles and where a heating and pressurizing process has been carried out
Implementation Method 2
safety is ensured by the polyolefin microporous film melting at approximately 130° C. and the porous holes being clogged
Data Source
AI summary
A battery is provided. The battery includes a positive electrode; a negative electrode; and a separator; wherein the separator comprises a base which is formed from a non-woven fabric, and a surface layer which is formed on at least one of the surfaces of the base and includes a resin material and inorganic particles, and the separator is formed by a pressurizing process being carried out on at least one of the surfaces of the surface layer, a thickness of the base is 12 μm or more and 30 μm or less, an average particle diameter of primary particles of the inorganic particles is 0.3 μm or more and 0.8 μm or less, a thickness of the surface layer is 1 μm or more and 10 μm or less.