Coated Battery Separator for Adhesion and Heat Shrinkage Control
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Solution Overview
Problem
Existing secondary battery separators face challenges in maintaining electrode adhesion and heat shrinkage when using metal hydroxides as inorganic materials, with fatty acid-based dispersants increasing heat shrinkage and decreasing adhesion.
Innovation Solution
A coated separator is developed using a titanium-based or silane-based coupling agent with hydroxides of metals or metal oxides, along with a dispersant and binder, to enhance dispersibility and adhesion while controlling heat shrinkage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal hydroxide is used as an inorganic material for the separator coating layer, then flame retardancy is improved, but dispersion force with cyano-based resins deteriorates
Solution Approach 1:
The patent introduces a coupling agent as an intermediary substance between the metal hydroxide particles and the cyano-based resin binder. This coupling agent has dual functionality: one end interacts with the metal hydroxide surface while the other end interacts with the resin, thereby mediating the interface and improving both dispersion and adhesion without compromising flame retardancy
Solution Approach 2:
The patent modifies the surface properties of metal hydroxide particles by treating them with coupling agents, changing their surface chemistry parameters. This allows the inorganic particles to maintain their flame-retardant properties while gaining improved compatibility and dispersion characteristics in the organic resin matrix
2Stability of the object's composition
If a fatty acid-based dispersant is used to secure dispersion force of metal hydroxide, then dispersibility is improved, but heat shrinkage increases and electrode adhesion decreases
Solution Approach 1:
The coupling agent serves as a superior intermediary compared to fatty acid dispersants. It provides both dispersion function and adhesion promotion simultaneously, eliminating the need to choose between dispersibility and electrode adhesion. The coupling agent's molecular structure enables it to bridge inorganic particles and organic resin while maintaining strong electrode interface
Solution Approach 2:
The patent creates a composite coating system where the coupling agent forms a bridging layer between inorganic metal hydroxide particles and the organic cyano-based resin. This composite structure combines the flame retardancy of metal hydroxide with the adhesive properties of the resin, achieving both dispersion and adhesion simultaneously
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 improves electrode adhesion and reduces heat shrinkage, ensuring better safety and performance of secondary batteries by maintaining uniform physical properties and dispersibility of inorganic materials in the coating layer.
Implementation Method 1
a coupling agent so as to secure dispersibility of a hydroxide of a metal, or a hydroxide of a metal oxide
Implementation Method 2
electrode adhesion
Implementation Method 3
heat shrinkage of a separator
Data Source
AI summary
A coated separator for a secondary battery including a separator substrate including a porous polymer resin; and a coating layer present on at least one surface of the separator substrate. The coating layer includes an inorganic material and a coupling agent, the inorganic material comprises a hydroxide of a metal, or a hydroxide of a metal oxide, and the coupling agent is a titanium-based or a silane-based coupling agent.