Secondary Battery Anode Binder Gradient for Adhesion and Ion Diffusion
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Solution Overview
Problem
Existing anodes for non-aqueous electrolyte secondary batteries face issues with binder distribution, leading to adhesion problems between the anode active material and current collector, which affects battery performance and efficiency.
Innovation Solution
Optimizing the distribution of rubber-based and water-soluble polymer-based binders in the anode mixture layer, with specific ratios and positions to enhance adhesion and prevent peeling, while maintaining lithium ion diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the same amount of binders is used throughout the anode mixture layer, then the manufacturing process is simple, but the adhesion between anode active material and current collector is insufficient and peeling occurs
Solution Approach 1:
The patent applies local quality by creating different binder compositions at different positions within the anode mixture layer. Specifically, the binder content near the current collector (first region) is optimized differently from the binder content away from the current collector (second region). This spatial variation in binder quality ensures strong adhesion at the critical interface while maintaining appropriate properties in the bulk material, resolving the contradiction between simple manufacturing and effective adhesion.
2Strength
If more rubber-based binder is used to improve adhesion, then binding force increases, but lithium ion diffusion may be hindered
Solution Approach 1:
The patent resolves this contradiction by applying local quality through spatially differentiated binder composition. The rubber-based binder content is optimized at specific regions (particularly near the current collector where adhesion is critical) rather than uniformly distributed. This localized optimization ensures sufficient binding force at the interface while preventing excessive binder accumulation that would block lithium ion diffusion pathways in the bulk material.
Solution Approach 2:
The patent employs parameter changes by varying the binder composition parameters (ratios of rubber-based binder, water-soluble polymer-based binder, and conductive material) across different regions of the anode mixture layer. By changing these compositional parameters locally, the patent achieves optimal adhesion strength near the current collector while maintaining adequate lithium ion diffusion capability in other regions, thus resolving the contradiction between binding force and ion diffusion.
3Strength
If water-soluble polymer-based binder is increased to improve adhesion, then binding force improves, but electrode peeling still occurs due to insufficient distribution control
Solution Approach 1:
The patent applies local quality by creating region-specific binder compositions where the water-soluble polymer-based binder content is optimized at different positions within the anode mixture layer. This spatial variation ensures that adhesion-promoting components are concentrated where needed (near the current collector interface) while preventing uniform over-saturation that could lead to peeling. The local quality approach transforms the insufficient distribution control into an optimized spatial distribution.
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 optimized binder distribution improves adhesion between the anode active material and current collector, reducing peeling and enhancing battery performance and efficiency.
Implementation Method 1
a rubber-based binder and a water-soluble polymer-based binder are used to maintain binding force between an anode active material and an anode current collector
Data Source
Figure 1
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Figure 3(a)~3(b)
AI summary
The present invention relates to an anode for a non-aqueous electrolyte secondary battery, comprising: an anode current collector; and an anode mixture layer formed on the anode current collector, the anode mixture layer containing an anode active material, a conductor, a rubber-based binder, and a water-soluble polymer-based binder, wherein the anode mixture layer comprises, relative to a total weight thereof, 1.0-2.5 wt% of the rubber-based binder and 0.5-1.5 wt% of the water-soluble polymer based binder, and wherein when the anode mixture layer is divided into ten equal parts in the thickness direction based on the current collector, the ratio (CA) of the content of the rubber-based binder in the section between 0 and 3 to the total content of the rubber-based binder compared to the ratio (CB) of the content of the water-soluble polymer-based binder in the section between 0 and 3 to the total content of the water-soluble polymer-based binder, that is, CA/CB, is more than 1.0, while in the section between 7 to 10, CA/CB is less than 1.0.