Jelly-Roll Separator Coating for Thermal Stability
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Solution Overview
Problem
Existing secondary battery electrode assemblies face issues with heat resistance and separation of organic-inorganic porous coating layers during fabrication, leading to defects and reduced battery performance.
Innovation Solution
A jelly-roll type electrode assembly with porous substrates and coating layers formed only in areas where the separators contact the anode and cathode, using a mixture of inorganic particles and a binder polymer, and avoiding formation on the outermost surface or mandrel contact areas to prevent separation and ensure high thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If porous coating layers are formed on both sides of the separator to improve heat resistance, then thermal stability is improved, but the coating layers may separate from the separator during winding or cutting
Solution Approach 1:
The patent applies porous coating layers only to specific regions of the separator where thermal protection is needed (areas contacting electrodes), rather than uniformly coating the entire separator. This localized approach maintains heat resistance where required while avoiding adhesion problems in regions where coating would cause separation during manufacturing.
Solution Approach 2:
The separator is divided into different functional zones: regions with porous coating layers for thermal protection and regions without coating to ensure proper adhesion and manufacturing reliability. This segmentation allows the system to simultaneously achieve heat resistance and prevent coating separation.
2Temperature
If porous coating layers are formed on the outermost surface to improve heat resistance, then thermal stability is improved, but surface friction increases causing defects during fabrication
Solution Approach 1:
The patent strategically places porous coating layers only in internal regions of the separator that contact electrodes, deliberately excluding the outermost surfaces. This ensures heat resistance where thermally critical while maintaining low surface friction on outer surfaces to prevent fabrication defects.
3Area of stationary object
If the separator is made longer than the electrodes to ensure proper coverage, then electrode coverage is improved, but the separator undergoes extreme thermal shrinkage at high temperatures
Solution Approach 1:
The patent applies thermal protection (porous coating layers) specifically to regions of the separator that require heat resistance, rather than uniformly treating the entire separator. This allows the separator to maintain its dimensional stability at high temperatures in critical areas while preserving the necessary coverage area.
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 prevents separation of porous coating layers during winding and cutting, enhances heat resistance, and reduces surface friction, resulting in improved battery assembly yield and performance.
Implementation Method 1
Porous polyolefin substrates tend to undergo extreme thermal shrinkage at temperatures of 100 °C or higher due to their material characteristics and production processes including elongation. Under such circumstances, the introduction of an organic-inorganic porous coating layer into a separator has been suggested as an approach aimed at achieving improved heat resistance.
Implementation Method 2
the introduction of an organic-inorganic porous coating layer into a separator
Data Source
Figure 1~2
Figure 3
AI summary
A jelly-roll type electrode assembly is disclosed. The jelly-roll type electrode assembly includes an anode, a cathode, and separators interposed between the anode and the cathode and having a greater length than width. Each of the separators is longer than the anode and the cathode. Each of the separators has a porous substrate and porous coating layers formed on both surfaces of the porous substrate. The porous coating layers include a mixture of inorganic particles and a binder polymer. The porous coating layers are formed only in areas where the separators are in contact with the anode and the cathode. The porous coating layers enhance the heat resistance of the separators. Due to the enhanced heat resistance, the separators can prevent the performance of a battery from deteriorating. In addition, the porous coating layers can be prevented from being separated from the separators during battery assembly processing.