Non-Aqueous Battery Electrode Binder for Storage Stability and Peel Strength
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Solution Overview
Problem
Conventional binder compositions for non-aqueous secondary battery electrodes fail to simultaneously achieve uniform polymer dispersion after storage, high peel strength at elevated temperatures, and low internal resistance in secondary batteries.
Innovation Solution
A binder composition containing a polymer with specific chemical composition and median diameter, including an aromatic vinyl monomer unit, a conjugated diene monomer unit, and a hydrophilic monomer unit, with a loss tangent tan δ and loss modulus G″ within specific ranges, ensuring excellent stationary stability and high-temperature peel strength while reducing internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional binder compositions are used, then the electrode can be formed with basic binding function, but the polymer uniformity after stationary storage deteriorates and peel strength at high temperature is insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling the loss tangent tan δ (0.05-0.40) and loss modulus G'' (500-2000 Pa) of the binder polymer to achieve optimal balance between stationary stability and high-temperature peel strength. The median diameter is controlled within 50-800 nm, and the glass transition temperature is set between -50°C and 50°C, creating a binder composition that maintains both uniformity during storage and bonding strength at elevated temperatures.
Solution Approach 2:
The patent employs composite materials by formulating a binder composition containing multiple components: a specific polymer (styrene-butadiene random copolymer with controlled properties), carboxymethyl cellulose, and conductive carbon black. This composite approach allows the binder to simultaneously achieve polymer uniformity during storage and maintain peel strength at high temperatures through the synergistic effects of its constituents.
2Strength
If binder composition is optimized for high peel strength, then electrode binding capacity improves, but internal resistance of secondary battery increases
Solution Approach 1:
The patent resolves this contradiction by changing the parameter of loss tangent tan δ to a specific range (0.05-0.40), which optimizes the balance between peel strength and electrical conductivity. Additionally, the loss modulus G'' is controlled within 500-2000 Pa, and conductive carbon black is added to the binder composition, ensuring that high binding capacity does not come at the cost of increased internal resistance.
3Stability of the object's composition
If polymer dispersion uniformity is improved, then electrode structure stability increases, but peel strength at high temperature decreases
Solution Approach 1:
The patent applies parameter changes by controlling the glass transition temperature of the binder polymer within -50°C to 50°C and the median diameter between 50-800 nm. These parameter optimizations ensure that the binder maintains appropriate flexibility and adhesion at high temperatures while preserving electrode structure stability during storage.
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 composition effectively maintains polymer uniformity, enhances peel strength after high-temperature exposure, and lowers internal resistance in non-aqueous secondary batteries, improving both electrode stability and battery performance.
Implementation Method 1
the polymer has a loss tangent tan δ of not less than 0.001 and less than 0.40 and a loss modulus G'' of 1,600 kPa or less
Implementation Method 2
an electrode mixed material layer (positive electrode mixed material layer or negative electrode mixed material layer) formed on the current collector
Data Source
AI summary
A binder composition for a non-aqueous secondary battery electrode contains water and a polymer that includes an aromatic vinyl monomer unit, a conjugated diene monomer unit, and a hydrophilic monomer unit. The polymer has a median diameter of not less than 50 nm and not more than 800 nm, and the proportional content of the hydrophilic monomer unit in the polymer is not less than 4.0 mass % and not more than 20 mass %. Moreover, the polymer has a loss tangent tan δ of not less than 0.001 and less than 0.40 and a loss modulus G″ of 1,600 kPa or less.