Binder Composition for Non-Aqueous Battery Functional Layer
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Solution Overview
Problem
Conventional water-soluble polymer-containing compositions for non-aqueous secondary battery functional layers face issues with productivity and performance, including residual water leading to electrolyte solution decomposition and gas generation, and instability during application, resulting in poor cycle characteristics and uniformity of the functional layer.
Innovation Solution
A binder composition with a water-soluble polymer having a contact angle with water between 40° and 80° and a degree of swelling in electrolyte solution between 1.0 and 3.0, which enhances stability and reduces residual water content, improving the durability and uniformity of the functional layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a water-soluble polymer is used as a binder in an aqueous composition for a functional layer, then environmental impact is improved, but residual water remains in the functional layer causing electrolyte solution decomposition and gas generation
Solution Approach 1:
The patent applies parameter changes by carefully controlling the molecular weight, composition, and structure of the water-soluble polymer binder. Specifically, it uses a polymer with a weight-average molecular weight of 10,000 to 1,000,000 and specific monomer unit compositions (40-100 mass% (meth)acrylamide, 0-60 mass% other hydrophilic monomers) to optimize water removal during drying while maintaining environmental benefits of aqueous formulations
Solution Approach 2:
The patent employs composite materials by combining the water-soluble polymer binder with specific additives including 0.1-10 mass% of compounds containing unsaturated carboxylic acid groups, 0-20 mass% of fluorine-containing compounds, and various inorganic fillers. This composite approach enhances the functional layer's ability to remove residual water while maintaining environmental compatibility
2Ease of manufacture
If conventional water-soluble polymer compositions are used for functional layers, then ease of manufacture is improved, but functional layer productivity and secondary battery performance deteriorate
Solution Approach 1:
The patent optimizes manufacturing parameters by specifying precise ranges for polymer molecular weight (10,000-1,000,000), monomer composition ratios, and additive concentrations. These parameter optimizations enable better control over functional layer formation, drying characteristics, and final performance, thereby improving productivity while maintaining ease of manufacture
Solution Approach 2:
The patent incorporates preliminary action by pre-formulating the binder composition with specific additives and optimizing polymer structure before application. This includes pre-mixing the water-soluble polymer with unsaturated carboxylic acid compounds and fluorine-containing compounds in defined ratios, which prepares the composition for optimal performance during the coating and drying processes, enhancing both productivity and battery performance
3Strength
If highly hydrophilic water-soluble polymer is used to improve close adherence, then adhesion is improved, but water removal during drying is insufficient leading to residual water problems
Solution Approach 1:
The patent resolves this contradiction by adjusting the hydrophilicity parameter of the polymer through controlled selection of monomer units and molecular weight. The specification of 40-100 mass% (meth)acrylamide content and 10,000-1,000,000 molecular weight creates an optimal balance where the polymer maintains sufficient adhesion while enabling effective water removal during the drying process
Solution Approach 2:
The patent uses composite materials by combining the water-soluble polymer with hydrophobic modifiers including fluorine-containing compounds (0-20 mass%) and compounds with unsaturated carboxylic acid groups (0.1-10 mass%). This composite structure allows the binder to maintain strong adhesion to the separator substrate while the hydrophobic components facilitate water removal during drying, preventing residual water issues
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 achieves excellent stability and cycle characteristics for non-aqueous secondary batteries by reducing residual water and enhancing the durability and uniformity of the functional layer, leading to improved battery performance.
Implementation Method 1
a water-soluble polymer having a contact angle with water of at least 40° and not more than 80° and a degree of swelling in electrolyte solution of more than a factor of 1.0 and not more than a factor of 3.0
Data Source
AI summary
Provided is a binder composition for a non-aqueous secondary battery functional layer that enables production of a composition for a non-aqueous secondary battery functional layer that has excellent stability and can cause a non-aqueous secondary battery to display excellent cycle characteristics. The binder composition contains a water-soluble polymer and water. The water-soluble polymer has a contact angle with water of at least 40° and not more than 80° and has a degree of swelling in electrolyte solution of more than a factor of 1.0 and not more than a factor of 3.0.