Cyanoethyl Polymer Binder for Battery Separator Adhesion
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Solution Overview
Problem
Current binders used for safety reinforced separators in secondary batteries do not ensure uniform distribution and strong adhesion of inorganic particles, leading to potential heat shrinkage issues due to non-uniform particle distribution.
Innovation Solution
A cyanoethyl group-containing polymer with low contents of specific functional groups, such as -OCH2CH2CONH2 and -OCH2CH2COOH, is used as a binder to improve the dispersion force and adhesive strength of inorganic particles on the polymer film, ensuring uniform distribution and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional binders are used to adhere inorganic particles to the polymer film, then adhesive strength is provided, but uniform distribution of inorganic particles is not achieved leading to localized heat shrinkage
Solution Approach 1:
The patent modifies the chemical parameters of the binder by controlling the content of specific functional groups (carboxyl and hydroxyl groups) to within specific ranges (carboxyl group content: 0.1-5.0 mmol/g, hydroxyl group content: 0.1-5.0 mmol/g). This parameter optimization enables the binder to simultaneously achieve strong adhesion and uniform particle distribution without requiring additional dispersant components.
Solution Approach 2:
The binder polymer is designed to perform multiple functions simultaneously: it acts as an adhesive for adhering inorganic particles, a dispersant for uniform particle distribution, and a binder for maintaining separator structure. This is achieved by optimizing the functional group content within specific ranges, allowing a single component to fulfill multiple roles that were previously requiring separate materials.
2Strength
If inorganic particles are not uniformly distributed on the polymer film, then adhesive strength may be maintained, but localized areas without inorganic particles cause heat shrinkage
Solution Approach 1:
The patent establishes specific ranges for functional group content (carboxyl: 0.1-5.0 mmol/g, hydroxyl: 0.1-5.0 mmol/g) that optimize both adhesive strength and heat shrinkage resistance. Within these ranges, the binder achieves uniform particle distribution that prevents localized heat shrinkage while maintaining overall adhesive strength.
Solution Approach 2:
Instead of adding separate dispersant components to achieve uniform distribution, the patent inverts the approach by optimizing the binder's functional group content to inherently provide both adhesion and uniform distribution. The controlled functional group content creates optimal interaction with inorganic particles, ensuring uniform distribution as a result of the binder's chemical properties rather than additional additives.
3Strength
If the binder contains high content of functional groups like -OCH2CH2CONH2 and -OCH2CH2COOH, then adhesive properties are enhanced, but dispersion force of inorganic particles deteriorates
Solution Approach 1:
The patent identifies and controls the content of specific functional groups (carboxyl and hydroxyl groups derived from -OCH2CH2CONH2 and -OCH2CH2COOH) within optimized ranges (0.1-5.0 mmol/g each). This parameter control balances the adhesive properties provided by these functional groups while preventing excessive interaction that would reduce dispersion force, thereby achieving both strong adhesion and good particle dispersion.
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 polymer effectively enhances the dispersion force and adhesive strength of inorganic particles, preventing heat shrinkage and maintaining separator integrity even under high temperatures.
Implementation Method 1
a binder is used in order to adhere the inorganic particles to the polymer film
Implementation Method 2
a dispersant for dispersing the inorganic particles upon coating the polymer film with the inorganic particles
Data Source
AI summary
A cyanoethyl group-containing polymer and a preparation method thereof are provided. The cyanoethyl group-containing polymer is characterized by having very low contents of functional groups other than cyanoethyl groups.