Battery Separator Coating With Coupling Agents for Heat Shrinkage
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Solution Overview
Problem
Existing coated separators for secondary batteries using metal hydroxides face issues with low dispersion force, leading to increased heat shrinkage and decreased electrode adhesion, which compromises the safety and performance of the battery.
Innovation Solution
A coated separator for secondary batteries is developed using a hydroxide of a metal or metal oxide as the inorganic material, combined with a titanium-based or silane-based coupling agent, along with a dispersant and binder, to enhance dispersibility and adhesion, thereby forming a uniform coating layer.
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 anchors to the metal hydroxide surface while the other end compatibilizes with the cyano-based resin, thereby achieving effective dispersion without compromising flame retardancy. This resolves the contradiction by mediating the interaction between the inorganic filler and organic binder.
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 patent changes the chemical parameter of the dispersing agent from fatty acid-based to a coupling agent with specific functional groups. This parameter change fundamentally alters the mechanism of dispersion: instead of using fatty acid molecules that interfere with electrode adhesion, the coupling agent provides dispersion through chemical bonding to metal hydroxide surfaces while maintaining compatibility with the binder system, thus preserving electrode adhesion properties.
3Reliability
If metal hydroxide is used in the separator coating layer, then safety against high temperatures is improved, but uniform dispersion becomes difficult
Solution Approach 1:
The coupling agent serves as a mediator that bridges the inorganic metal hydroxide particles and the organic binder matrix. By providing compatible interaction interfaces, it enables uniform distribution of metal hydroxide particles throughout the coating layer, achieving both high-temperature safety and uniform dispersion required for consistent manufacturing quality.
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 the secondary battery by maintaining uniform dispersion and mechanical strength of 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
a coupling agent so as to secure dispersibility... and electrode adhesion
Implementation Method 3
The coating layer of the SRS separator forms a porous structure by the inorganic particles and the binder and a volume in which a liquid electrolyte solution is placed is increased by virtue of the porous structure
Implementation Method 4
heat shrinkage of a separator
Data Source
AI summary
Disclosed herein is a coated separator for a secondary battery comprising a separator substrate including a porous polymer resin; and a coating layer coated on at least one surface of the separator substrate, wherein the coating layer comprises an inorganic material and a coupling agent, the inorganic material is a hydroxide of a metal, or a hydroxide of a metal oxide, and the coupling agent is a titanium (titanate)-based or a silane-based coupling agent.