Battery Functional Layer Composition for Adhesion and Cycle Output
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Solution Overview
Problem
Non-aqueous secondary battery functional layers face challenges with insufficient process adhesiveness and electrical characteristics, such as cycle and output characteristics, which affect productivity and performance.
Innovation Solution
A composition for a non-aqueous secondary battery functional layer is developed, comprising organic particles with specific chemical composition and properties, including an aromatic monovinyl monomer unit, (meth)acrylic acid alkyl ester monomer unit, crosslinkable monomer unit, and acidic group-containing monomer unit, combined with a binder, to enhance process adhesiveness and electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a functional layer is formed using conventional composition (PTL 1), then heat resistance and strength are improved, but process adhesiveness is insufficient
Solution Approach 1:
The patent uses a composite binder system comprising both a rubber component (polybutadiene or styrene-butadiene copolymer) and an acrylic component (polyacrylonitrile or polyacrylic acid). This composite material approach combines the adhesive properties of rubber with the bonding capabilities of acrylic polymers, achieving both heat resistance/strength and process adhesiveness simultaneously. The specific composition ratios (rubber 30-80 parts, acrylic 20-70 parts) are optimized to balance these competing requirements.
2Productivity
If battery members are stacked and transported during production, then productivity is improved, but position shifting occurs causing faults
Solution Approach 1:
The functional layer is designed to provide adhesion during the production process before the battery is fully assembled and sealed. The binder composition enables battery members to maintain their positions during stacking, cutting, and transportation operations. This preliminary adhesion action prevents position shifting and faults during manufacturing, allowing for efficient production workflows without compromising reliability.
3Reliability
If organic particles with high swelling ratio are used, then electrical characteristics are improved, but structural stability deteriorates
Solution Approach 1:
The patent carefully controls the swelling ratio of organic particles within a specific range (1.05-1.30 times). This parameter optimization allows the particles to expand sufficiently to provide good electrical characteristics and ion conductivity, while preventing excessive swelling that would compromise structural stability. The binder composition also plays a role in constraining particle expansion to maintain structural integrity.
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 functional layer formed using this composition exhibits excellent process adhesiveness and improved electrical characteristics, including cycle and low-temperature output characteristics, leading to enhanced performance and productivity of non-aqueous secondary batteries.
Implementation Method 1
the organic particles have a degree of swelling in non-aqueous electrolyte solution of more than a factor of 1 and not more than a factor of 2
Data Source
AI summary
A composition for a non-aqueous secondary battery functional layer contains organic particles having a specific chemical composition and properties, and a binder. The organic particles contained in the composition for a functional layer include an aromatic monovinyl monomer unit in a proportion of at least 20 mass% and not more than 70 mass% and a (meth)acrylic acid alkyl ester monomer unit in a proportion of at least 30 mass% and not more than 70 mass%. The organic particles have a degree of swelling in electrolyte solution of more than a factor of 1.0 and not more than a factor of 4.0, a volume-average particle diameter of at least 0.4 µm and not more than 1.0 µm, and a tetrahydrofuran-insoluble content of at least 20 mass% and not more than 70 mass%.