Reactive Emulsifier Binder for Secondary Battery Adhesion
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Solution Overview
Problem
Conventional binders for secondary battery electrodes fail to prevent separation between electrode active materials and current collectors, leading to decreased charge/discharge capacity and lifespan due to volume expansion and insufficient adhesion, while also allowing moisture impregnation that poses safety risks.
Innovation Solution
A binder comprising a polymer formed by polymerizing three or more kinds of monomers, including (meth)acrylic acid ester, vinyl, and unsaturated monocarbonic acid monomers, with a reactive emulsifying agent that reduces moisture impregnation and enhances adhesive force, thereby improving structural stability and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional binders like PVdF or SBR are used, then ease of manufacture is improved, but adhesion force and structural stability deteriorate due to insufficient binding strength and moisture impregnation
Solution Approach 1:
The patent changes the chemical composition parameters of the binder by using a copolymer containing specific functional groups (carboxyl, hydroxyl, or amine groups) with controlled content ratios. This chemical parameter change enables strong chemical bonding with electrode materials while maintaining ease of manufacture through conventional coating processes.
Solution Approach 2:
The patent creates a composite binder system by combining polymer base material with specific functional groups that provide both adhesion functionality and moisture resistance. This composite approach maintains manufacturing simplicity while achieving superior adhesion force and structural stability.
2Reliability
If binders with strong adhesion are used to prevent separation, then reliability is improved, but moisture impregnation increases leading to safety issues
Solution Approach 1:
The patent applies local quality by introducing specific functional groups (carboxyl, hydroxyl, or amine) at controlled concentrations (0.1-10 mmol/g) within the binder structure. These localized functional groups provide strong chemical bonding for adhesion while the overall binder composition maintains moisture resistance, resolving the contradiction between strong adhesion and moisture resistance.
3Quantity of substance
If electrode materials with high discharge capacity are used, then energy density is improved, but volume expansion increases causing separation and decreasing cycle life
Solution Approach 1:
The patent applies beforehand cushioning by using a binder with elastic functional groups and controlled glass transition temperature that can accommodate volume expansion of high-capacity electrode materials before separation occurs. This pre-compliance mechanism maintains structural stability even when electrode materials undergo significant volume changes during cycling.
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 binder effectively reduces moisture impregnation, enhances adhesive force, and improves cycle characteristics, leading to increased safety and performance of secondary battery electrodes by preventing separation and maintaining capacity over repeated charging/discharging cycles.
Implementation Method 1
the polymer has a glass transition temperature of -50°C to 0°C, based on the total weight of the binder, the (meth)acrylic acid ester monomer is 10 to 90% by weight... the reactive emulsifying agent contains a carbon-carbon double bond at one side thereof and contains a non-ionic emulsifying agent group at the other side thereof, wherein the non-ionic emulsifying agent group contains one or more watersoluble groups and one or more non-water soluble groups
Implementation Method 2
a binder for secondary battery electrodes comprising a polymer obtained by polymerizing three or more kinds of monomers with a reactive emulsifying agent... exhibits superior adhesion force... can prevent separation between the electrode active material, or between the electrode active material and the current collector upon fabrication of electrodes via strong adhesion
Implementation Method 3
the polymer has a glass transition temperature of -50°C to 0°C... exhibits superior adhesion force... can control volume expansion of electrode active materials upon repeated charging/discharging via strong physical properties, thus improving structural stability of electrodes
Data Source
AI summary
Provided is a binder for secondary battery electrodes comprising a polymer obtained by polymerizing three or more kinds of monomers with a reactive emulsifying agent. The binder reduces moisture impregnation, improves dispersibility and enhances adhesive force, thus providing a secondary battery with superior safety and cycle characteristics.