Core-Shell Functional Layer Composition for Electrolyte Wettability
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Solution Overview
Problem
Conventional electrochemical devices face challenges in achieving excellent process adhesiveness and electrolyte solution injectability during production, as well as storage characteristics, due to limitations in the functional layers used in these devices.
Innovation Solution
A composition for an electrochemical device functional layer is developed, comprising a particulate polymer with a core-shell structure, specific electrolyte solution contact angle, and volume-average particle diameter, along with a binder and heat-resistant fine particles, which enhances process adhesiveness and electrolyte solution injectability and storage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a functional layer is formed using conventional compositions (binder, inorganic particles, particulate polymer), then the basic structure is achieved, but process adhesiveness is insufficient
Solution Approach 1:
The patent uses a composite particulate polymer consisting of a core portion (polymer A) and a shell portion (polymer B) that at least partially covers the core. This core-shell composite structure combines the adhesive properties of polymer A with the electrolyte wettability of polymer B, achieving both excellent process adhesiveness and electrolyte solution injectability that cannot be obtained with conventional single-material functional layers.
Solution Approach 2:
The functional layer is designed with spatially differentiated properties: the core portion provides adhesive strength while the shell portion provides electrolyte wettability. This local differentiation of material functions within the particulate polymer allows different regions to perform different functions, simultaneously improving adhesiveness and electrolyte injectability.
2Temperature
If inorganic particles are used to form functional layer with high area proportion (>90%), then heat resistance is improved, but electrolyte solution injectability deteriorates
Solution Approach 1:
The shell portion (polymer B) acts as an intermediary between the inorganic particles/core portion and the electrolyte solution. It provides a surface that is highly wettable by electrolyte solution while allowing the underlying core portion to maintain heat resistance properties. This intermediary layer resolves the contradiction between heat resistance and electrolyte injectability.
Solution Approach 2:
The patent changes the surface properties of the functional layer by introducing a shell portion with different chemical composition and surface energy characteristics. This parameter change in surface chemistry enables high electrolyte wettability while maintaining the thermal stability provided by the core portion and inorganic particles.
3Strength
If particulate polymer with large particle diameter is used, then process adhesiveness is improved, but manufacturing precision deteriorates
Solution Approach 1:
The functional layer is segmented into multiple components: inorganic particles, binder, and particulate polymer with core-shell structure. This segmentation allows each component to perform its specific function independently, enabling the use of larger particulate polymer for adhesiveness while maintaining uniformity through the distributed nature of the segmented components.
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 described composition forms a functional layer with improved adhesiveness and injectability, leading to enhanced performance and storage characteristics in electrochemical devices, as demonstrated by increased peel strength and capacity maintenance rates.
Implementation Method 1
the particulate polymer has an electrolyte solution contact angle of not less than 0° and not more than 35°
Implementation Method 2
a functional layer that has excellent process adhesiveness
Data Source
AI summary
A composition for an electrochemical device functional layer contains a particulate polymer, a binder, and heat-resistant fine particles. The particulate polymer has a core-shell structure including a core portion formed of a polymer A and a shell portion formed of a polymer B that at least partially covers an outer surface of the core portion, with the polymer A and the polymer B being different from each other. The particulate polymer also has an electrolyte solution contact angle of not less than 0° and not more than 35° and a volume-average particle diameter of not less than 1.0 μm and not more than 10.0 μm.