Secondary Battery Separator Coating for Adhesion and Air Permeability
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Solution Overview
Problem
Lithium batteries face issues with interface resistance increase during rolling, leading to deteriorated capacity and high rate charge and discharge characteristics, requiring a separator with improved adhesion and stability to maintain battery performance and safety.
Innovation Solution
A separator for lithium batteries incorporating an adhesive layer composed of first and second vinylidene fluoride-based polymer particles with different solation temperatures, along with an inorganic layer, to enhance adhesion and air permeability, reducing interface resistance and maintaining battery shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the separator is made thinner to reduce weight and improve battery miniaturization, then weight reduction and miniaturization are achieved, but adhesion strength and stability deteriorate
Solution Approach 1:
The patent applies composite materials by combining vinylidene fluoride-based polymer particles with different solation temperatures in the adhesive layer. This composite approach allows the adhesive layer to maintain strong adhesion while being thin, resolving the contradiction between weight reduction and adhesion strength maintenance.
Solution Approach 2:
The patent applies local quality by creating an adhesive layer with specific localized properties - using polymer particles with different solation temperatures (85°C or lower and 100°C or higher) in specific proportions. This localized functional differentiation allows the adhesive layer to provide both strong adhesion and thermal stability without increasing overall separator thickness.
2Ease of manufacture
If the separator structure is simplified to reduce manufacturing complexity, then manufacturing ease is improved, but adhesion and stability deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the solation temperature distribution of polymer particles in the adhesive layer. By controlling the ratio of low-solation-temperature particles (85°C or lower) to high-solation-temperature particles (100°C or higher) within specific ranges, the patent achieves both manufacturing feasibility and superior adhesion stability without complex processing steps.
3Reliability
If interface resistance is reduced to improve charge-discharge characteristics, then battery performance is improved, but adhesion stability may deteriorate
Solution Approach 1:
The patent applies local quality by creating an adhesive layer with spatially differentiated polymer composition - using vinylidene fluoride-based polymer particles with different solation temperatures in specific proportions. This localized functional differentiation reduces interface resistance while maintaining adhesion stability throughout the separator structure.
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 provides improved adhesion and stability, ensuring stable battery performance by preventing deformation and enhancing capacity, lifespan, and safety through reduced interface resistance.
Implementation Method 1
an adhesive layer located on the inorganic layer, wherein the adhesive layer includes first vinylidene fluoride-based polymer particles and second vinylidene fluoride-based polymer particles, having different solation temperatures
Data Source
AI summary
Disclosed are a separator for a secondary battery, and a secondary battery including the same, the separator including a porous substrate, an inorganic layer located on at least one side of the porous substrate, and an adhesive layer located on the inorganic layer, wherein the adhesive layer includes first vinylidene fluoride-based polymer particles and second vinylidene fluoride-based polymer particles, having different solation temperatures.