Battery Electrode Binder Composition for High-Solid Slurry Coating
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Solution Overview
Problem
Conventional binder compositions for non-aqueous secondary battery electrodes often result in low solid content concentrations and inadequate peel strength in electrode mixed material layers, leading to suboptimal battery performance due to gelation and excessive viscosity issues.
Innovation Solution
A binder composition with a polymer containing an ethylenically unsaturated acid monomer unit in specific proportions, mixed with an organic solvent, maintains a viscosity within a specific range to achieve high solid content concentrations and enhanced peel strength in the electrode mixed material layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional binder compositions are used, then the slurry composition can be formed, but the solid content concentration becomes low due to gelation and excessive viscosity
Solution Approach 1:
The patent changes the chemical composition parameters of the binder by specifying a copolymer with particular monomer ratios (70-95 mass% first monomer, 5-30 mass% second monomer) and molecular weight range (10,000-1,000,000). These parameter changes optimize the binder's interaction with the solvent, preventing gelation and controlling viscosity to enable high solid content concentration (70-90 mass%) in the slurry composition.
Solution Approach 2:
The patent uses a composite binder system formed by copolymerizing two different monomers with specific functional characteristics. The first monomer (ethyleneically unsaturated carboxylic acid ester) provides binding functionality, while the second monomer (another ethyleneically unsaturated monomer) modifies the polymer's solubility and rheological properties. This composite material approach prevents gelation and enables high solid content slurry formation.
2Strength
If conventional binder compositions are used, then the electrode mixed material layer can be formed, but the peel strength becomes inadequate
Solution Approach 1:
The patent optimizes the binder's molecular parameters including selecting a copolymer with specific monomer composition (70-95 mass% first monomer, 5-30 mass% second monomer) and controlled molecular weight (10,000-1,000,000). These parameter changes enhance the binder's adhesion properties, achieving peel strength of 5 N/m or more while maintaining adequate binding capacity for fixed active material.
3Strength
If high solid content concentration is achieved, then peel strength is enhanced, but viscosity control becomes challenging
Solution Approach 1:
The patent achieves viscosity control at high solid content concentration by precisely controlling the binder's chemical parameters: copolymer composition (70-95 mass% first monomer, 5-30 mass% second monomer) and molecular weight (10,000-1,000,000). These parameter changes ensure the slurry maintains appropriate viscosity for coating operations while achieving high solid content (70-90 mass%) and enhanced peel strength.
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 proposed binder composition allows for a higher solid content concentration in the slurry composition, improving the peel strength and overall battery characteristics, including rate and cycle characteristics of non-aqueous secondary batteries.
Implementation Method 1
the polymer A has a viscosity of 3 mPa·s or more and 800 mPa·s or less at a shear rate of 0.1 s-1
Data Source
AI summary
A binder composition for a non-aqueous secondary battery electrode contains an organic solvent and a binder that includes a polymer A including an ethylenically unsaturated acid monomer unit in a proportion of not less than 1.00 mass% and not more than 10.00 mass%. The polymer A has a viscosity of 10,000 mPa·s or less at a shear rate of 0.1 s-1 when mixed with the organic solvent in a concentration of 8 mass% to obtain a mixture.