Battery Separator Coating for High Adhesion Without Resistance Rise
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Solution Overview
Problem
Existing separators for secondary batteries face challenges in maintaining sufficient adhesion between electrodes and separators, leading to separation issues during manufacturing and use, especially in high-capacity batteries, and conventional binders reduce battery performance due to increased resistance and reduced electrolyte impregnability.
Innovation Solution
A high-adhesion separator is developed with a coating layer containing a copolymer of a humidification phase separable polymer and vinyl acetate, which maintains high adhesive force and improves phase separation characteristics, along with an inorganic material to enhance mechanical strength and porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a large amount of binder is used to increase adhesion force, then adhesive force between electrodes and separator is improved, but battery resistance increases and electrolyte impregnability is reduced
Solution Approach 1:
The invention changes the chemical composition parameters of the binder by using a copolymer with specific ratios of vinyl acetate (50-90 wt%) and humidification phase separable polymer (10-50 wt%). This compositional parameter change achieves high adhesion force while maintaining appropriate binder quantity, resolving the contradiction between adhesion strength and battery resistance.
Solution Approach 2:
The invention uses a composite binder system comprising vinyl acetate and humidification phase separable polymer in specific proportions. This composite material approach combines the adhesive properties of vinyl acetate with the phase separation characteristics of the other polymer, achieving both high adhesion and proper porosity for electrolyte penetration.
2Strength
If polyvinyl acetate is used as binder to increase adhesive force, then adhesion is improved, but humidification phase separation characteristics are reduced
Solution Approach 1:
The invention merges two different polymer systems - vinyl acetate (providing adhesion) and humidification phase separable polymer (providing phase separation characteristics). By combining these materials in a copolymer structure with specific ratios, the invention achieves both high adhesive force and good humidification phase separation characteristics that neither material could provide alone.
3Strength
If binder amount is increased to prevent electrode separation, then adhesion force is improved, but battery capacity and lifespan are reduced
Solution Approach 1:
The invention optimizes the binder composition parameters using a copolymer with controlled ratios of vinyl acetate (50-90 wt%) and humidification phase separable polymer (10-50 wt%). This parameter optimization achieves sufficient adhesion force to prevent electrode separation while maintaining appropriate binder quantity, thereby preserving battery capacity and extending lifespan.
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 separator enhances adhesion between electrodes, improves impregnability, and increases battery capacity and lifespan while maintaining porosity, thus optimizing battery performance.
Implementation Method 1
the binder includes a copolymer of a humidification phase separable polymer and vinyl acetate
Data Source
Figure 1
AI summary
Disclosed are a high-adhesion separator for batteries, the high-adhesion separator including a porous substrate and a coating layer formed on at least one surface of the porous substrate, the coating layer including an inorganic material, wherein the coating layer includes a copolymer of a humidification phase separable polymer and vinyl acetate, and a secondary battery including the same.