Coated Lithium Battery Separator for Low Heat Shrinkage
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Solution Overview
Problem
Rechargeable lithium batteries face challenges with high heat shrinkage and membrane resistance, which affect their stability and capacity.
Innovation Solution
A separator for lithium batteries is developed with a coating layer containing a (meth)acryl-based binder and a mixture of cubic and plate-shaped fillers, which reduces heat shrinkage and membrane resistance, enhancing heat resistance and bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separator is used, then the battery can operate, but the heat shrinkage rate is high which reduces stability and lifetime
Solution Approach 1:
The patent applies composite materials by combining multiple filler types (alumina, silica, boehmite) with specific surface area ranges (5-50 m²/g) in a coating layer on the separator. This composite approach reduces heat shrinkage rate while maintaining structural integrity, directly improving battery stability and lifetime without sacrificing operational functionality.
2Quantity of substance
If a conventional separator is used, then the structure is simple, but the membrane resistance is high which reduces battery capacity
Solution Approach 1:
The patent employs porous materials by incorporating fillers with specific surface areas (5-50 m²/g) that create optimized pore structures in the coating layer. This reduces membrane resistance and enhances ion transport, thereby increasing battery capacity while the porous structure itself adds functional complexity to the separator design.
3Strength
If the separator structure is simplified, then manufacturing is easier, but heat resistance and bonding strength are insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling filler surface area (5-50 m²/g), filler particle size distribution, and coating layer composition. These parameter optimizations enhance heat resistance and bonding strength through improved thermal stability and adhesion, while the standardized parameter ranges facilitate reproducible manufacturing processes.
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 low heat shrinkage rates and membrane resistance, improving the stability and capacity of rechargeable lithium batteries.
Implementation Method 1
The separator may have a low membrane resistance and a high heat resistance, resulting in low heat shrinkage
Implementation Method 2
The separator may have a low membrane resistance and a high heat resistance, resulting in low heat shrinkage
Data Source
AI summary
The present disclosure relates to a separator and a rechargeable lithium battery including the separator. The separator includes a porous substrate and a coating layer on a surface of the porous substrate. The coating layer includes a heat-resistant layer including a binder and a filler, and an adhesive layer including an adhesive binder on the heat-resistant layer. The binder includes a (meth)acryl-based binder including a first structural unit derived from (meth)acrylic acid, (meth)acrylate, or a salt thereof, a second structural unit derived from hydroxyalkyl (meth)acrylate, and a third structural unit derived from (meth)acrylamido sulfonic acid or a salt thereof. The filler includes a mixture of cubic filler having a particle diameter D50 ranging from about 50 nm to about 250 nm and a plate-shaped filler having a particle diameter D50 ranging from about 250 nm to about 350 nm in a weight ratio of about 20:80 to about 80:20.