Silicon-Carbon Anode Slurry Composition for Stable Battery Cycling
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Solution Overview
Problem
Existing non-aqueous electrolyte secondary batteries face challenges in improving cycle characteristics while maintaining high capacity, particularly due to the dispersion state of silicon-containing materials in the negative electrode mixture layer not being adequately addressed in conventional technologies.
Innovation Solution
A negative electrode for non-aqueous electrolyte secondary batteries is designed with a specific amount of a water-soluble polymer adsorbed and released relative to the negative electrode active material, ensuring a good dispersion state of the silicon-containing material, which includes a carbon material and a silicon-containing material, thereby enhancing compatibility with the dispersion medium and inhibiting active material deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional negative electrode mixture slurry is used with carbon material only, then manufacturing process is simple, but cycle characteristics are poor due to aggregation of silicon-containing material
Solution Approach 1:
The patent uses a composite slurry system combining water-soluble polymer (carboxymethylcellulose), styrene-butadiene rubber emulsion, and silicon-containing material with carbon material. This composite approach prevents aggregation of silicon-containing material while maintaining good cycle characteristics, resolving the contradiction between reliability improvement and complexity increase.
Solution Approach 2:
The water-soluble polymer acts as an intermediary substance that mediates between the silicon-containing material and the dispersion medium. It adsorbs onto the silicon-containing material surface, preventing aggregation and ensuring uniform dispersion, thus improving cycle characteristics without requiring complex processing.
2Strength
If high amount of binder is used in negative electrode mixture layer, then adhesion is improved, but active material content decreases reducing battery capacity
Solution Approach 1:
The patent changes the chemical parameters of the binder system by using water-soluble polymers with specific adsorption characteristics. This allows achieving adequate adhesion with lower total binder content, thereby preserving more active material content for high battery capacity.
Solution Approach 2:
The binder system provides localized adhesion at the interface between active material particles and the electrode structure, rather than requiring uniform distribution throughout the entire electrode. This localized binding action maintains adhesion strength while minimizing the overall binder quantity needed.
3Reliability
If uniform dispersion of silicon-containing material is achieved, then cycle characteristics improve, but slurry stability becomes difficult to control
Solution Approach 1:
The patent employs a feedback mechanism where the water-soluble polymer adsorbs onto silicon-containing material particles, sensing their presence and preventing aggregation. This self-regulating system maintains uniform dispersion automatically, improving cycle characteristics while keeping slurry composition stable and controllable.
Solution Approach 2:
The binder system provides self-service by automatically adsorbing onto silicon-containing material particles and maintaining uniform dispersion without requiring external intervention. This self-regulating behavior ensures both good cycle characteristics and stable slurry composition simultaneously.
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 solution results in a battery with high capacity and excellent cycle characteristics by achieving a uniform dispersion state of the negative electrode active material, stabilizing the slurry, and inhibiting capacity decrease due to active material deterioration.
Implementation Method 1
the water-soluble polymer at an amount of greater than or equal to 0.50 mass% relative to the negative electrode active material is adsorbed on the negative electrode active material
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
A negative electrode (12) according to an embodiment of the present invention comprises: a negative electrode core (40); and a negative electrode mixture layer (41) that is positioned on the negative electrode core (40), the negative electrode mixture layer (41) containing a negative electrode active material (50) and a water-soluble polymer (51). The water-soluble polymer (51) is present such that an amount of 0.50 mass% or more relative to the negative electrode active material (50) is adsorbed onto the negative electrode active material (50), and an amount of 1.05 mass% or less is separated from the negative electrode active material (50). The negative electrode active material (50) includes a carbon material and a silicon-containing material.