One-Side Coated Battery Separator with Amide Resin
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Solution Overview
Problem
The existing separators for non-aqueous secondary batteries with a coating film on one side of the substrate face challenges in electrolyte permeability, leading to increased resistance and suboptimal battery characteristics, as they are prone to static electricity and poor slippage, which affects manufacturing and performance.
Innovation Solution
A separator with a porous substrate and a porous layer containing a resin with amide, imide, or sulfonyl bonds on one side, featuring a specific DSC temperature difference and incorporating inorganic particles, enhances electrolyte permeability and affinity, improving battery characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating film is provided on both sides of the polyethylene film, then heat resistance and chemical stability are improved, but the separator thickness increases and electrolyte permeability deteriorates
Solution Approach 1:
The separator is divided into multiple layers with different functions: a polyethylene base film providing mechanical strength and shutdown function, and thin aramid coating films (0.1-5 μm) on one or both sides providing heat resistance. This segmentation allows each layer to be optimized independently, reducing total thickness while maintaining heat resistance.
Solution Approach 2:
The aramid coating is applied selectively to specific regions or surfaces of the polyethylene film rather than uniformly throughout. The coating thickness is controlled to be 0.1-5 μm on the surface, providing localized heat resistance where needed while preserving electrolyte permeability in the bulk separator structure.
2Reliability
If a coating film is provided on both sides of the polyethylene film, then heat resistance is improved, but electrolyte permeability deteriorates
Solution Approach 1:
The aramid coating film is designed with a porous structure having controlled pore size and distribution. This porous architecture allows electrolyte to penetrate through the coating layer while the aramid polymer matrix provides heat resistance. The pore structure ensures that electrolyte permeability is maintained despite the presence of the coating film.
3Reliability
If aramid or nylon is used in the separator, then heat resistance is improved, but static electricity accumulation and poor slippage occur
Solution Approach 1:
The physical and chemical parameters of the aramid coating are optimized to reduce static electricity accumulation. This includes controlling coating thickness (0.1-5 μm), adjusting porosity, and selecting appropriate aramid polymer characteristics. These parameter changes reduce the polar group density at the surface, minimizing static electricity generation while preserving heat resistance.
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 efficient electrolyte permeation and impregnation, resulting in improved battery performance and characteristics, such as reduced resistance and enhanced dischargeability and heat resistance.
Implementation Method 1
A separator with a porous substrate and a porous layer containing a resin with amide, imide, or sulfonyl bonds on one side, featuring a specific DSC temperature difference and incorporating inorganic particles, enhances electrolyte permeability and affinity
Implementation Method 2
in the porous substrate, an absolute value of a difference between a temperature of an endothermic peak observed at from 120°C to 145°C in a temperature raising process 1, and a temperature of an endothermic peak observed at from 120°C to 145°C in a temperature raising process 2, is 1.50°C or higher in differential scanning calorimetry (DSC) measurement
Data Source
AI summary
An embodiment of the present invention provides a separator for a non-aqueous secondary battery containing: a porous layer that is provided on only one side of the porous substrate, and that contains a resin having at least one bonding group selected from the group consisting of an amide bond, an imide bond, and a sulfonyl bond, in which, in the porous substrate, an absolute value of a difference between a temperature of an endothermic peak observed at from 120°C to 145°C in a temperature raising process 1, and a temperature of an endothermic peak observed at from 120°C to 145°C in a temperature raising process 2, is 1.50°C or higher in DSC measurement when the temperature raising process 1 of continuously raising the temperature from 30°C to 200°C at a temperature change rate of 5°C/min in a nitrogen atmosphere, and the temperature raising process 2 of lowering the temperature from 200°C to 30°C and raising the temperature from 30°C to 200°C, are performed.