Electrode Binder Composition for High-Temperature Durability
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Solution Overview
Problem
Existing binder materials for electrical storage devices do not have sufficient characteristics under high temperatures, particularly for use in electric cars, where durability and adhesiveness are compromised.
Innovation Solution
A binder composition comprising specific ratios of repeating units derived from conjugated diene, aromatic vinyl, and unsaturated carboxylic acid compounds, with controlled dynamic viscoelasticity properties, is used to enhance adhesiveness and reduce internal resistance, particularly suitable for electrodes with active materials like silicon or graphite.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional binder materials are used, then basic binding function is provided, but charge-discharge durability under high temperature is insufficient
Solution Approach 1:
The invention changes the chemical composition parameters of the binder by specifying precise ratios of repeating units: 15-60 parts conjugated diene, 35-75 parts aromatic vinyl, and 1-10 parts unsaturated carboxylic acid per 100 parts total repeating units. This compositional parameter optimization enables the binder to maintain adhesiveness and reduce internal resistance under high temperature conditions, resolving the contradiction between basic binding function and high temperature durability.
Solution Approach 2:
The invention creates a composite binder structure by combining multiple types of repeating units with different functional properties. The conjugated diene provides flexibility and adhesion, the aromatic vinyl contributes to thermal stability and binding strength, and the unsaturated carboxylic acid enhances interface compatibility with active materials. This composite approach allows the binder to simultaneously achieve basic binding function and superior charge-discharge durability under high temperature.
2Strength
If binder material with high adhesiveness is used, then binding ability and powder fall-off resistance improve, but internal resistance increases
Solution Approach 1:
The invention optimizes the chemical composition parameters to achieve a balance between adhesiveness and internal resistance. By controlling the content of each repeating unit type and specifying the tanδ ratio (tanδ(100°C)/tanδ(Tp) × 100 ≥ 0.5), the binder achieves sufficient binding strength while maintaining low internal resistance, thus resolving the contradiction between strong adhesion and low electrical resistance.
3Reliability
If binder material is optimized for room temperature performance, then basic electrode characteristics are achieved, but high temperature durability is compromised
Solution Approach 1:
The invention defines specific parameter ranges for repeating unit composition that can be implemented through conventional polymerization processes. The specified ratios (15-60 parts conjugated diene, 35-75 parts aromatic vinyl, 1-10 parts unsaturated carboxylic acid) provide a clear formulation guide that balances performance optimization with manufacturing simplicity, resolving the contradiction between high temperature durability and composition complexity.
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 improves charge-discharge durability and reduces internal resistance of electrical storage devices under high temperatures, enabling better performance with materials having large lithium storage capacity.
Implementation Method 1
an adhesive ability between the active material and the current collector
Implementation Method 2
Such binder material expresses satisfactory adhesiveness and reduces internal resistance of a battery resulting from the binder material
Data Source
Figure 1
AI summary
Provided is a binder composition for an electrical storage device, which enables the production of an electrical storage device electrode excellent in charge-discharge durability characteristic under high temperature by improving adhesiveness under high temperature and reducing internal resistance thereunder. The binder composition for an electrical storage device includes: a polymer (A) and a liquid medium (B), wherein, with respect to 100 parts by mass in total of repeating units contained in the polymer (A), the polymer (A) contains: 15 parts by mass to 60 parts by mass of a repeating unit (a1) derived from a conjugated diene compound; 35 parts by mass to 75 parts by mass of a repeating unit (a2) derived from an aromatic vinyl compound; and 1 part by mass to 10 parts by mass of a repeating unit (a3) derived from an unsaturated carboxylic acid, and wherein, when, in dynamic viscoelasticity measurement of the polymer (A), a peak top of tanδ (loss elastic modulus/storage elastic modulus) is represented by tanδ(Tp), and tanδ at 100°C is represented by tanδ(100°C), a relationship of the following expression (1) is satisfied. tanδ(100°C)/tanδ(Tp)×100≤10 (1)