Fibrillated Polymer Fiber Thickener for Battery Electrode Adhesion
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Solution Overview
Problem
The migration of binder and thickener during the drying process in the production of battery electrodes leads to reduced adhesion between the active material layer and the collector, affecting battery performance, particularly cycle durability and output characteristics.
Innovation Solution
The use of fibrillated polymer fibers as a thickener in the active material layer forming paste, which reduces mobility and prevents the binder and thickener from rising to the surface, ensuring adequate adhesion by suppressing the migration phenomenon during drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an active material layer forming paste containing binder and thickener is coated onto a collector and dried rapidly, then productivity is improved, but the binder and thickener migrate to the surface layer during drying, reducing adhesion between the active material layer and the collector
Solution Approach 1:
The invention changes the physical-chemical parameters of the thickener by using fibrillated polymer fibers instead of conventional non-fibrillated polymers. The fibrillation process creates a three-dimensional network structure with significantly increased surface area and altered rheological properties, transforming the thickener's behavior during drying to prevent migration while maintaining rapid drying capability
Solution Approach 2:
The invention uses a composite material system where fibrillated polymer fibers form a three-dimensional network structure within the paste. This composite structure, combining the fibrillated thickener with the binder and active material particles, creates a rigid framework that locks polymer materials in place during drying, preventing migration to the surface while allowing rapid solvent evaporation
2Ease of manufacture
If conventional non-fibrillated polymer thickeners are used, then the paste can be applied easily, but the polymer materials migrate to the surface during drying, causing reduced adhesion and poorer battery performance
Solution Approach 1:
The invention transforms the thickener from a conventional non-fibrillated polymer to a fibrillated polymer with fundamentally different physical parameters. The fibrillation process creates a three-dimensional network structure with vastly increased surface area and altered flow characteristics, changing how the thickener interacts with other paste components during application and drying to maintain uniform distribution
Solution Approach 2:
The fibrillated polymer fibers act as an intermediary structure that mediates between the binder and the solvent. The three-dimensional network formed by fibrillated fibers creates a rigid framework that controls solvent evaporation and prevents binder migration, while still allowing the paste to be applied smoothly to the collector
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
This method enhances the adhesion between the active material layer and the collector, improving battery performance by maintaining the distribution of polymer materials, allowing for quicker drying and increased productivity, resulting in superior output characteristics and cycle durability.
Implementation Method 1
The surface of the fibrillated polymer fibers unravels, whereupon numerous fine fibers (fibrils) become formed on the fibers. As a result, the polymer fibers exhibit larger surface irregularities, increased frictional resistance with a solvent, and lower mobility in the solvent
Implementation Method 2
a step of forming an active material layer on the collector by drying the applied paste coat material
Data Source
AI summary
A main object of the present invention is to provide a method for producing a battery electrode that has excellent adhesion between a collector and an active material layer by suppressing a migration phenomenon. The method for producing a battery electrode of the present invention is a method for producing a battery electrode 30 that has a structure in which an active material layer 20 that includes an active material 22 is held on a collector 10. The method includes a step of applying, onto the collector 10, an active material layer forming paste that contains the active material 22 and polymer materials 24, 26 in a solvent; and a step of drying the applied paste coat material, to form thereby the active material layer 20 on the collector 10. Fibrillated polymer fibers 26 are used as at least one of the polymer materials 24, 26.