Core-Shell Functional Layer Composition for Adhesion-Resistance Balance
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Solution Overview
Problem
Conventional functional layers in electrochemical devices face a challenge in achieving a balance between high adhesive strength after immersion in electrolyte solution and low resistance, which affects the overall performance of the device.
Innovation Solution
A composition for an electrochemical device functional layer using a particulate polymer with a specific core-shell structure, where the core portion has a degree of swelling in electrolyte solution of not less than ×0.1 and less than ×5, and a volume-average particle diameter of not less than 0.1 µm and not more than 10 µm, along with a shell portion coverage of not less than 1% and not more than 90%, is employed to form a functional layer with improved adhesive strength and reduced resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional composition for functional layer is used, then the functional layer can be formed with basic adhesive properties, but the adhesive strength after immersion in electrolyte solution is insufficient and resistance is high
Solution Approach 1:
The patent uses a core-shell structured particulate polymer where the core portion and shell portion are made of different polymers with complementary properties. The core provides adhesive strength through controlled swelling, while the shell provides structural integrity and low resistance, achieving a balance between adhesive strength and device resistance that neither polymer could achieve alone.
Solution Approach 2:
The functional layer is designed with spatially differentiated properties through the core-shell structure. The core portion (with specific swelling properties) is localized to provide adhesive function at the interface, while the shell portion provides protective and conductive properties on the outer surface, creating local optimization of both adhesive strength and resistance characteristics.
2Strength
If the degree of swelling of the polymer is increased to improve adhesive strength, then adhesive strength after immersion improves, but device resistance increases
Solution Approach 1:
The polymer particle is segmented into core and shell portions with different swelling characteristics. The core portion has controlled swelling (×0.1 to ×5) to provide adhesive strength, while the shell portion has limited swelling to maintain low resistance, allowing the system to achieve both high adhesive strength and low resistance through functional segmentation.
Solution Approach 2:
By combining two polymers with different swelling properties in a core-shell structure, the invention achieves a composite material where the core provides adhesive swelling and the shell provides resistance control, resolving the contradiction between swelling-induced adhesion and resistance increase.
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 achieves a good balance of high adhesive strength after immersion in electrolyte solution and low resistance, resulting in electrochemical devices with enhanced electrochemical characteristics such as improved cycle characteristics.
Implementation Method 1
a polymer A of the core portion has a degree of swelling in electrolyte solution of not less than ×0.1 and less than ×5
Data Source
AI summary
A composition for a functional layer contains a particulate polymer having a core-shell structure. In this particulate polymer, coverage of an outer surface of the core portion by the shell portion is not less than 1% and not more than 90%, and a polymer A of the core portion has a degree of swelling in electrolyte solution of not less than ×0.1 and less than ×5, includes an unsaturated carboxylic acid ester monomer unit having a carbon number of 6 or less, and has a volume-average particle diameter of not less than 0.1 µm and not more than 10 µm.