Anode Binder Gradient for Adhesion and Peeling Resistance
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Solution Overview
Problem
In non-aqueous electrolyte secondary batteries, the distribution of rubber-based and water-soluble polymer-based binders in the anode mixture layer affects the binding force and battery performance, with existing technologies not optimizing binder distribution effectively to prevent peeling and enhance performance.
Innovation Solution
The anode mixture layer is optimized with a specific distribution of rubber-based and water-soluble polymer-based binders, where the rubber-based binder content is higher near the anode current collector and the water-soluble polymer-based binder content is higher near the anode surface, with defined weight percentages and ratios across different intervals of the anode thickness, to enhance adhesion and prevent peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If uniform distribution of rubber-based and water-soluble polymer-based binders is used in the anode mixture layer, then the manufacturing process is simple, but the adhesion strength between anode active material and current collector is insufficient and peeling occurs
Solution Approach 1:
The patent applies local quality by creating different binder distributions in different regions of the anode mixture layer. Specifically, the rubber-based binder is concentrated near the current collector interface (first region) to maximize adhesion strength, while the water-soluble polymer-based binder is concentrated toward the anode surface (second region) to prevent peeling and maintain structural integrity. This spatial differentiation of binder functions resolves the contradiction between simple manufacturing and high adhesion strength.
2Strength
If higher rubber-based binder content is used throughout the anode mixture layer, then adhesion to current collector improves, but peeling resistance and battery performance deteriorate due to excessive binder accumulation
Solution Approach 1:
The patent resolves this contradiction by locally concentrating the rubber-based binder in the first region near the current collector interface, where adhesion is most critical, while limiting its presence in the second region toward the anode surface. Simultaneously, the water-soluble polymer-based binder is concentrated in the second region to provide peeling resistance. This localized functional distribution ensures high adhesion without excessive binder accumulation that would cause peeling.
Solution Approach 2:
The patent uses a composite binder system combining two different binder materials with complementary functions. The rubber-based binder provides strong adhesion to the current collector, while the water-soluble polymer-based binder provides peeling resistance and structural stability. By combining these materials in a specific spatial distribution, the patent achieves both high adhesion strength and excellent peeling resistance without the drawbacks of using either binder alone throughout the entire layer.
3Reliability
If optimized binder distribution with specific weight percentages is implemented, then adhesion and peeling resistance improve, but the manufacturing precision and control complexity increase
Solution Approach 1:
The patent specifies precise parameter ranges for binder content and distribution to achieve optimal performance. The rubber-based binder is controlled at 0.5-2.0 wt% in the first region and 0.1-0.5 wt% in the second region, while the water-soluble polymer-based binder is controlled at 0.1-1.0 wt% in the first region and 0.5-2.0 wt% in the second region. These quantified parameter specifications transform the complex distribution control into measurable and controllable manufacturing parameters, making the optimized distribution achievable through standard manufacturing processes.
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.