Composition for electrochemical device functional layer and method of producing same, functional layer for electrochemical device, laminate for electrochemical device, and electrochemical device
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Solution Overview
Problem
There is a need for novel compositions for functional layers in electrochemical devices to enhance their performance beyond existing capabilities, particularly in terms of adhesiveness, heat resistance, and uniformity.
Innovation Solution
A composition for an electrochemical device functional layer is developed, comprising a particulate polymer with a sea-island structure and a binder, where the particulate polymer has a volume-average particle diameter between 1.0 μm and 10.0 μm, and includes heat-resistant fine particles, (meth)acrylic acid ester monomer units, and specific ratios of polymer A and B to achieve balanced attributes such as adhesiveness, blocking resistance, and process adhesiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional binder and inorganic particles composition is used for the functional layer, then the manufacturing process is simple, but the uniformity and adhesiveness of the functional layer are insufficient
Solution Approach 1:
The patent uses a particulate polymer with a sea-island heterophase structure composed of polymer A (island phase) and polymer B (sea phase). This composite structure combines the advantages of both polymers: polymer A provides adhesiveness through swelling in electrolyte solution, while polymer B provides structural integrity and processability. The heterophase structure allows the functional layer to achieve both uniformity and adhesiveness simultaneously.
Solution Approach 2:
The sea-island structure creates local quality variations within the particulate polymer. The island phases of polymer A are distributed throughout the sea phase of polymer B, creating localized adhesive regions that swell in electrolyte solution. This local quality differentiation enables the material to exhibit both adhesiveness (from polymer A regions) and structural stability (from polymer B regions) in different locations within the same particle.
2Strength
If the functional layer uses high adhesiveness materials, then the layer bonding is improved, but the heat resistance deteriorates
Solution Approach 1:
The particulate polymer combines polymer A with high adhesiveness (swelling properties) and polymer B with heat resistance in a sea-island structure. The polymer B sea phase provides thermal stability and structural integrity at high temperatures, while the polymer A island phases provide adhesiveness through controlled swelling in electrolyte solution. This composite approach allows the functional layer to achieve both high adhesiveness and heat resistance simultaneously.
Solution Approach 2:
The patent controls the glass transition temperatures of the polymers to optimize performance. Polymer A has a glass transition temperature of -50°C to 0°C for swelling and adhesiveness, while polymer B has a glass transition temperature of 0°C to 50°C for heat resistance. By carefully selecting and controlling these temperature parameters, the functional layer achieves both adhesiveness and thermal stability.
3Manufacturing precision
If the particulate polymer has small particle size for uniformity, then the layer uniformity is improved, but the adhesiveness deteriorates
Solution Approach 1:
The sea-island heterophase structure within the particulate polymer allows small particles to maintain high adhesiveness. The polymer A island phases are distributed throughout the polymer B sea phase, ensuring that even in small particles (1.0-10.0 μm), there are sufficient adhesive sites (island phases) to provide strong adhesion to the separator substrate while the small particle size ensures uniform distribution and coating.
Solution Approach 2:
The heterogeneous sea-island structure creates local adhesive regions (polymer A islands) within each particle, ensuring that even small particles have distributed adhesive sites throughout their volume. This local quality distribution allows small particles to maintain high adhesiveness while achieving uniform layer formation.
Data Source
AI summary
A composition for an electrochemical device functional layer contains a binder and a particulate polymer having a sea-island structure such that the number of island phases per unit area, in cross-section observation according to specific conditions, is not less than 1 and not more than 200.