Multilayer Secondary Battery Electrode Binders for Adhesion and Slurry Balance
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Solution Overview
Problem
Existing electrodes for secondary batteries face challenges in achieving excellent adhesion, resistance characteristics, and processability, particularly in multilayer structures where binder migration and differences in slurry viscosity and solids content can lead to reduced adhesion and impaired resistance.
Innovation Solution
A multilayer electrode structure is developed with a current collector, a first electrode mixture layer containing a first active material and a first binder, and a second electrode mixture layer containing a second active material and a second binder. The weight ratio of the first binder to the first electrode mixture layer is greater than or equal to the weight ratio of the second binder to the second electrode mixture layer, and the molecular weight of the second binder is greater than that of the first binder, optimizing adhesion and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a multilayer electrode structure is used to improve adhesion and resistance characteristics, then adhesion strength increases, but differences in slurry viscosity and solids content between layers cause binder migration and reduced processability
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molecular weight of binders in different layers and adjusting binder content ratios. The first binder has molecular weight 800,000-1,500,000 while the second binder has molecular weight 1,000,000-2,000,000, with specific weight ratio ranges that optimize both adhesion strength and slurry consistency for manufacturability
Solution Approach 2:
The patent uses composite materials by combining different binder types (first binder and second binder with different molecular weights) in a multilayer structure. This composite approach allows each layer to contribute different properties, achieving overall adhesion enhancement while maintaining processability through complementary material characteristics
2Strength
If binder content is increased to improve adhesion, then adhesion strength increases, but resistance characteristics deteriorate due to binder migration
Solution Approach 1:
The patent applies local quality by having different binder characteristics in different layers. The first layer contains binder with molecular weight 800,000-1,500,000 while the second layer contains binder with molecular weight 1,000,000-2,000,000. This localized differentiation prevents binder migration while maintaining adhesion in each specific region, thereby preserving resistance characteristics
Solution Approach 2:
The patent changes the molecular weight parameter of binders between layers to control binder behavior. By setting specific molecular weight ranges and weight ratios, the patent optimizes adhesion strength without causing resistance deterioration through binder migration
3Ease of manufacture
If slurry viscosity difference between layers is reduced to improve processability, then ease of manufacture increases, but adhesion and resistance characteristics may be compromised
Solution Approach 1:
The patent applies parameter changes by selecting specific molecular weight ranges for binders that naturally result in comparable slurry viscosities. The first binder (800,000-1,500,000) and second binder (1,000,000-2,000,000) are chosen to achieve viscosity compatibility, enabling easy manufacturing while preserving adhesion strength through proper binder content ratios
Data Source
AI summary
An electrode for a secondary battery according to one embodiment of the present invention comprises: a current collector; a first electrode mixture layer disposed on the current collector and including a first active material and a first binder; and a second electrode mixture layer disposed on the first electrode mixture layer and including a second active material and a second binder, wherein the weight ratio of the first binder in the first electrode mixture layer is equal to or greater than the weight ratio of the second binder in the second electrode mixture layer, and the electrode adhesive force with the current collector is 0.37 N/18 mm or greater. According to one embodiment of the present invention, provided are an electrode for a secondary battery having excellent electrode adhesion, resistance characteristics, etc., and a method for manufacturing same.