Battery Electrode Binder Composition for Adhesion and Slurry Dispersion
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Solution Overview
Problem
Conventional binder compositions for non-aqueous secondary battery electrodes lack sufficient dispersibility and adhesiveness, leading to suboptimal performance in terms of electrode formability, substrate adherence, and flexibility.
Innovation Solution
A binder composition comprising a polymer that includes an acidic group-containing monomer unit, a hydroxy group-containing acrylic acid ester monomer unit, and a hydroxy group-containing methacrylic acid ester monomer unit, in specific proportions, with a total proportional content of the hydroxy group-containing monomer units within a specific range and a weight-average molecular weight within a specific range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional binder composition containing a water-soluble polymer with high ethylenically unsaturated carboxylic acid ester monomer content is used, then substrate close adherence and flexibility are improved, but dispersibility of the slurry composition deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the binder polymer by incorporating specific monomer units (carboxyl group-containing, hydroxyl group-containing acrylic acid ester, and hydroxyl group-containing methacrylic acid ester) in defined proportions. This compositional parameter change enables the polymer to achieve both high substrate adherence and excellent dispersibility simultaneously, resolving the technical contradiction between these two properties.
2Ease of manufacture
If a conventional binder composition is used, then electrode formability is maintained, but adhesiveness and close adherence among components in the electrode mixed material layer are insufficient
Solution Approach 1:
The patent creates a composite binder polymer structure combining three types of monomer units (carboxyl group-containing, hydroxyl group-containing acrylic acid ester, and hydroxyl group-containing methacrylic acid ester) in specific ratios. This composite material approach allows the binder to provide both good electrode formability and enhanced adhesiveness among components, resolving the contradiction between ease of manufacture and strength of adhesion.
3Strength
If the weight-average molecular weight of the binder polymer is increased to improve adhesiveness, then close adherence is enhanced, but dispersibility and flexibility are reduced
Solution Approach 1:
The patent optimizes the weight-average molecular weight parameter of the binder polymer to a specific range (50,000 to 500,000). This parameter change, combined with the specific monomer composition, enables the polymer to achieve high close adherence while maintaining good dispersibility and flexibility, resolving the contradiction between strength of adhesion and dispersibility.
Data Source
AI summary
Provided is a binder composition for a non-aqueous secondary battery electrode that is capable of producing a slurry composition for a non-aqueous secondary battery electrode having excellent dispersibility and that can cause an electrode mixed material layer to display excellent adhesiveness and flexibility. The binder composition for a non-aqueous secondary battery electrode contains a polymer X. The polymer X includes not less than 3 mass % and less than 10 mass % of an acidic group-containing monomer unit, 55-90 mass % of a hydroxy group-containing acrylic acid ester monomer unit, and 5-30 mass % of a hydroxy group-containing methacrylic acid ester monomer unit. Total proportional content of the hydroxy group-containing acrylic acid ester monomer unit and hydroxy group-containing methacrylic acid ester monomer unit in the polymer X is 60-97 mass %. The polymer X has a weight-average molecular weight of not less than 50,000 and less than 500,000.