Styrene-Butadiene-Acrylonitrile Binder for Battery Electrodes
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Solution Overview
Problem
Conventional polymer binders for secondary battery electrodes have insufficient binding capacity, flexibility, and resistance to bending and cracks, leading to issues with electrode-coating layer tackiness and durability.
Innovation Solution
A copolymer latex binder is developed through emulsion polymerization using a specific monomer composition, including aliphatic conjugated diene-based, unsaturated carboxylic acid alkyl ester, and ethylene-based unsaturated carboxylic acid monomers, with 50-100% toluene-insolubility, to enhance binding capacity and flexibility while reducing tackiness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fluorine-based polymer is used as binder, then binding capacity is improved, but organic solvent volatilization occurs and large amounts are required which inhibits conductivity
Solution Approach 1:
The patent changes the chemical composition parameters of the binder by using a copolymer latex with specific monomer ratios (30-70 wt% styrene, 10-40 wt% butadiene, 5-20 wt% acrylonitrile) and controlled gel content (20-80%), thereby achieving sufficient binding capacity without requiring large amounts of binder that would inhibit conductivity
Solution Approach 2:
The patent replaces the fluorine-based polymer with a styrene-butadiene-acrylonitrile copolymer latex that uses water as dispersion medium instead of organic solvents, eliminating the harmful volatilization effect while maintaining binding functionality
2Object-generated harmful factors
If aqueous dispersion of non fluorine-based polymer is used, then organic solvent volatilization is reduced, but binding capacity to current collector and active material is insufficient
Solution Approach 1:
The patent creates a composite binder system by combining three different monomer components (styrene, butadiene, and acrylonitrile) in specific ratios, where each component contributes different properties: styrene provides structural framework, butadiene provides flexibility and adhesion, and acrylonitrile enhances polarity for better binding to active materials, achieving superior binding capacity through compositional synergy
Solution Approach 2:
The patent optimizes the gel content parameter to a specific range (20-80%) to balance the cross-linked network structure that provides binding strength with the flexibility needed for adhesion to current collector and active material, thereby achieving sufficient binding capacity in aqueous dispersion
3Manufacturing precision
If conventional polymer binder is used, then electrode coating can be formed, but resistance to bending and cracks is insufficient and flexibility is poor
Solution Approach 1:
The patent changes the glass transition temperature parameter of the binder by adjusting the butadiene content (10-40 wt%) and acrylonitrile content (5-20 wt%) to achieve optimal flexibility and elasticity, enabling the electrode coating to resist bending and cracks while maintaining proper formation
Solution Approach 2:
The patent incorporates butadiene units with high elasticity into the copolymer structure, creating a flexible network that can accommodate mechanical deformation, thereby improving the electrode coating's resistance to bending and cracks
4Strength
If polymer binder with high binding capacity is used, then binding to active material is improved, but electrode coating layer tackiness increases
Solution Approach 1:
The patent balances the polar and non-polar components in the copolymer structure by controlling the ratio of acrylonitrile (polar, enhances binding) to styrene (non-polar, reduces tackiness), achieving optimal binding capacity while minimizing unwanted tackiness of the electrode coating layer
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 provides an electrode-coating layer with improved binding capacity, low tackiness, excellent resistance to bending and cracks, and enhanced flexibility, resulting in better workability and performance.
Implementation Method 1
a polymer binder is used as the binder, and an active material (positive electrode active material and negative electrode component material) is blended with the polymer binder to prepare an electrode composition, and the electrode composition is applied on the current collector and dried, thereby binding the active material to the current collector
Implementation Method 2
an electrode-coating layer having a low tackiness, excellent resistance to bending and cracks, and excellent flexibility can be formed
Data Source
AI summary
A binder for secondary battery electrodes contains a copolymer latex obtained by emulsion polymerization of a monomer composition containing 12.0 to 39.5 wt % of an aliphatic conjugated diene-based monomer, 1.5 to 8.5 wt % of an unsaturated carboxylic acid alkyl ester monomer, 0.1 to 10.0 wt % of an ethylene-based unsaturated carboxylic acid monomer, and 42.0 to 86.4 wt % of a monomer that is copolymerizable therewith, wherein 50 to 100 wt % of the copolymer latex is toluene-insoluble.