Battery Electrode Binder Composition for Crack-Resistant Flexible Layers
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Solution Overview
Problem
Conventional binder compositions for non-aqueous secondary battery electrodes do not adequately achieve flexibility in the electrode mixed material layer, leading to potential cracking during battery production processes.
Innovation Solution
A binder composition containing a polymer X with specific proportions of an acidic group-containing monomer unit and a repeating unit derived from an unsaturated monomer A, having defined solubility and glass-transition temperature, is used to enhance the flexibility of the electrode mixed material layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional binder compositions are used, then the electrode mixed material layer can be formed, but the flexibility is insufficient leading to cracking during production
Solution Approach 1:
The patent changes the chemical composition parameters of the binder polymer by specifying precise proportions of acidic group-containing monomer units (3-20 mass%) and unsaturated monomer A units (5-50 mass%), along with controlling the glass-transition temperature (40°C or lower) and solubility characteristics. These parameter changes optimize the flexibility and cracking resistance of the electrode mixed material layer.
Solution Approach 2:
The invention uses a composite polymer structure combining multiple monomer units with different functions: acidic group-containing monomers for adhesion, unsaturated monomer A for flexibility, and other monomers for structural integrity. This composite approach creates a binder that simultaneously achieves binding strength and flexibility to prevent cracking.
2Reliability
If the binder composition is optimized for flexibility, then cracking is reduced, but the internal resistance may increase
Solution Approach 1:
The patent carefully balances the composition parameters to achieve both low cracking and low internal resistance. The acidic group-containing monomer content is controlled at 3-20 mass% to provide sufficient adhesion without excessive flexibility that would increase internal resistance. The glass-transition temperature is set at 40°C or lower to ensure flexibility while maintaining electrical conductivity.
Data Source
AI summary
A binder composition for a non-aqueous secondary battery electrode contains a polymer X that includes an acidic group-containing monomer unit in a proportion of not less than 3 mass % and not more than 20 mass % and a repeating unit derived from an unsaturated monomer A in a proportion of not less than 5 mass % and less than 50 mass %. The unsaturated monomer A has a solubility in water of not less than 1 g/100 mL and not more than 15 g/100 mL and has a glass-transition temperature of 40° C. or lower.