Battery Separator Resin Gradient for Strength and Flexibility
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Solution Overview
Problem
Conventional nonaqueous electrolyte secondary battery separators have insufficient mechanical strength, particularly after the heat-resistant layer is peeled off from the polyolefin porous film, which affects their puncture strength and flexibility.
Innovation Solution
A nonaqueous electrolyte secondary battery separator with a mixed layer containing a heat-resistant resin and a porous base material, where the heat-resistant resin is non-uniformly distributed, providing improved mechanical strength and flexibility by maintaining a specific ratio of nitrogen content at different energy dispersive X-ray analysis voltages, and optionally including a filler in the heat-resistant layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat-resistant layer is formed on a polyolefin porous film by causing resin to penetrate into the porous film, then heat resistance is improved, but mechanical strength deteriorates after the heat-resistant layer is peeled off
Solution Approach 1:
The patent applies local quality by creating a mixed layer where heat-resistant resin is non-uniformly distributed within the porous base material. The resin concentration varies through the thickness, with higher concentration near the surface providing heat resistance, while the gradual transition maintains the mechanical integrity of the polyolefin porous film structure.
Solution Approach 2:
The patent uses composite materials by combining heat-resistant resin with polyolefin-based porous film to create a mixed layer. This composite structure integrates the heat resistance properties of the heat-resistant resin with the mechanical strength and porosity of the polyolefin film, achieving both thermal stability and structural integrity.
2Strength
If heat-resistant resin is added to improve mechanical strength, then puncture strength is improved, but flexibility deteriorates
Solution Approach 1:
The patent applies local quality by creating a mixed layer where heat-resistant resin is non-uniformly distributed within the porous base material. The resin concentration varies through the thickness, with higher concentration near the surface providing heat resistance, while the gradual transition maintains the mechanical integrity of the polyolefin porous film structure.
Solution Approach 2:
The patent uses parameter changes by controlling the concentration and distribution of heat-resistant resin through the thickness of the mixed layer. By adjusting the resin content gradient and using EDS analysis at different acceleration voltages to characterize the distribution, the patent optimizes the balance between puncture strength and flexibility.
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 separator achieves enhanced mechanical strength, including puncture resistance, while retaining flexibility, thereby improving the safety and performance of nonaqueous electrolyte secondary batteries.
Implementation Method 1
when an energy dispersive X-ray analysis is carried out at an acceleration voltage of 1.5 kV on the mixed layer and N2 is a proportion of N (nitrogen) present when an energy dispersive X-ray analysis is carried out at an acceleration voltage of 5.0 kV on the mixed layer
Data Source
AI summary
As a nonaqueous electrolyte secondary battery separator which has improved mechanical strength and which retains flexibility, provided is a nonaqueous electrolyte secondary battery separator containing a heat-resistant resin that contains N (nitrogen) and a porous base material that includes a porous film containing a polyolefin-based resin as a main component. A ratio of N2 to N1 is not less than 50% and not more than 80%, where N1 is a proportion of N (nitrogen) present when an energy dispersive X-ray analysis is carried out at an acceleration voltage of 1.5 kV and N2 is a proportion of N (nitrogen) present when an energy dispersive X-ray analysis is carried out at an acceleration voltage of 5.0 kV.