Anode Binder Gradient for Adhesion and Lithium-Ion Diffusion
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Solution Overview
Problem
In non-aqueous electrolyte secondary batteries, the distribution of rubber-based and water-soluble polymer-based binders affects the binding force between the anode active material and the current collector, leading to issues such as peeling of the anode mixture layer and reduced battery performance.
Innovation Solution
The anode mixture layer is optimized with a specific distribution of rubber-based binder (1.0 wt % to 2.5 wt %) and water-soluble polymer-based binder (0.5 wt % to 1.5 wt %), where the rubber-based binder content is higher near the anode current collector and the water-soluble polymer-based binder content is higher on the surface, with a CA/CB ratio greater than 1.0 at intervals 0 to 3 and less than 1.0 at intervals 7 to 10, to enhance adhesion and prevent peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If uniform distribution of rubber-based binder and water-soluble polymer-based binder is used in the anode mixture layer, then the manufacturing process is simple, but the adhesion between anode active material and current collector is insufficient leading to peeling
Solution Approach 1:
The patent applies local quality by creating non-uniform binder distribution where the rubber-based binder content varies through the thickness of the anode mixture layer. Specifically, the ratio of rubber-based binder to water-soluble polymer-based binder is controlled to be 1.05 or more in the lower portion (near current collector) and 0.95 or less in the upper portion (near electrolyte), optimizing adhesion at the critical interface while maintaining overall structural integrity.
2Strength
If higher rubber-based binder content is used throughout the anode mixture layer, then adhesion to current collector improves, but lithium ion diffusion is hindered and battery performance decreases
Solution Approach 1:
The patent resolves this contradiction by applying local quality - concentrating the rubber-based binder in the lower portion of the anode mixture layer where adhesion is critical, while maintaining lower rubber-based binder content in the upper portion where lithium ion diffusion occurs. This spatial differentiation allows simultaneous optimization of both adhesion strength and ion transport properties.
Solution Approach 2:
The patent transitions from uniform binder distribution to gradient distribution through the thickness dimension. By controlling the vertical profile of rubber-based binder content (higher near current collector, lower near electrolyte), the patent optimizes both adhesion and ion diffusion without compromising either function.
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 optimized binder distribution improves the adhesion between the anode active material and the current collector, reducing peeling and enhancing battery performance by allowing better lithium ion diffusion and maintaining charging/discharging 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
Implementation Method 2
allowing better lithium ion diffusion and maintaining charging/discharging efficiency
Data Source
AI summary
An anode for a non-aqueous electrolyte secondary battery includes: an anode current collector; and an anode mixture layer formed on the anode current collector, containing an anode active material, a conductor, a rubber-based binder, and a water-soluble polymer-based binder. 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. When the anode mixture layer is divided into ten equal parts in the thickness direction based on the current collector, a ratio (CA/CB) at an interval of 0 to 3 of a content ratio (CA) of the rubber-based binder to a total content of the rubber-based binder to a content ratio (CB) of the water-soluble polymer-based binder to a total content of the water-soluble polymer-based binder is larger than 1.0, and a ratio (CA/CB) at an interval of 7 to 10 is smaller than 1.0.