Secondary Battery Anode Binder Gradient for Adhesion and Low Deformation
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Solution Overview
Problem
Current secondary batteries face challenges in minimizing deformation and achieving high energy density and capacity retention ratio, particularly due to issues with binder distribution and adhesion between the anode current collector and the anode active material.
Innovation Solution
The anode for secondary batteries incorporates a specific structure with a binder distribution that satisfies certain peak intensity ratios and content ratios between different areas, utilizing a butadiene-based binder and silicon-based materials, which enhances adhesion and minimizes deformation while improving energy density and capacity retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional anode mixture layer with uniform binder distribution is used, then the manufacturing process is simple, but the adhesion between anode current collector and anode active material is insufficient and deformation occurs
Solution Approach 1:
The binder is distributed non-uniformly in the anode mixture layer with higher concentration near the anode current collector and lower concentration toward the anode active material interface. This local quality variation optimizes adhesion strength at the critical interface while maintaining structural integrity, directly resolving the contradiction between adhesion strength and structural simplicity.
2Strength
If the binder content is increased to improve adhesion, then adhesion between layers improves, but the energy density and capacity retention ratio decrease
Solution Approach 1:
The binder concentration is optimized locally rather than uniformly distributed. The first area near the current collector has higher binder content for strong adhesion, while the second area has lower binder content to maximize active material loading and energy density. This resolves the contradiction by achieving sufficient adhesion with minimal total binder content.
Solution Approach 2:
Instead of uniformly distributing binder throughout the entire anode mixture layer, the invention applies binder selectively in the first area where adhesion is most critical. This partial action approach achieves the necessary adhesion strength without the excessive binder content that would reduce energy density and capacity retention.
3Quantity of substance
If the anode mixture layer thickness is increased to improve capacity, then the energy density improves, but the deformation of the anode increases
Solution Approach 1:
The binder distribution creates a gradient structure where the first area provides strong anchoring to the current collector and the second area accommodates the anode active material with reduced constraint. This local quality variation allows the anode mixture layer to expand and contract during cycling without excessive deformation, even at increased thickness for higher capacity.
Data Source
AI summary
An anode for a secondary battery and a secondary battery including the anode are disclosed. In an embodiment, the anode including an anode current collector; and an anode mixture layer formed on at least one surface of the anode current collector and including an anode active material and a binder, wherein the anode mixture layer includes a first area on the anode current collector and a second area on the first area, a sum of thicknesses of the first area and the second area is ¾ or less of a total thickness of the anode mixture layer, and the first area and the second area satisfy, according to energy dispersive X-ray spectroscopy, Formula 1 below: 1/7≤Iarea2/Iarea1≤⅔ [Formula 1]wherein Iarea1 refers to a peak intensity corresponding to the binder included in the first area, and Iarea2 refers to a peak intensity corresponding to the binder included in the second area.