Negative Electrode Layer Vibration Resistance
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries used in vehicles require higher vibration resistance, which existing methods using aqueous binders fail to adequately provide due to insufficient peeling strength and increased fragility when binder amounts are increased.
Innovation Solution
A flat laminated non-aqueous electrolyte secondary battery design with a negative electrode active material layer using 2-4% aqueous binder by mass, a rectangular shape with a long-to-short side ratio of 1:1.25, Young's modulus of 1.0-1.4 GPa, and a density of 1.4-1.6 g/cm³, allowing for improved binding properties and stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the amount of aqueous binder is increased to increase peeling strength, then the peeling strength between negative electrode current collector and active material layer is improved, but the electrode becomes hard and fragile
Solution Approach 1:
The patent optimizes the binder content parameter to a specific range (2-4 mass%) to achieve the desired peeling strength while preventing electrode fragility. This parameter optimization resolves the contradiction by finding the precise amount that provides sufficient binding without causing hardness and brittleness.
Solution Approach 2:
The patent uses a composite binder system combining aqueous binder (2-4 mass%) with organic solvent-based binder, creating a composite material that leverages the advantages of both binder types. The aqueous binder provides strong adhesion and environmental benefits, while the organic binder adds flexibility and prevents fragility.
2Quantity of substance
If the amount of aqueous binder is increased to improve binding effect, then the ratio of active material per volume is increased, but the vibration resistance is insufficient
Solution Approach 1:
The patent optimizes multiple parameters including binder content (2-4 mass%), aspect ratio (1.05-1.25), and electrode density to achieve both high active material ratio and sufficient vibration resistance. The coordinated optimization of these parameters resolves the contradiction between maximizing active material content and ensuring mechanical robustness.
Solution Approach 2:
The patent applies different binder compositions and amounts in different regions of the electrode structure. The aqueous binder is specifically positioned and quantified to provide localized adhesion enhancement at the current collector interface while maintaining overall electrode flexibility and vibration resistance.
3Strength
If the aspect ratio of negative electrode active material layer is optimized to improve peeling strength, then the stress distribution is improved, but the battery area to capacity ratio must be controlled
Solution Approach 1:
The patent sets the aspect ratio parameter to a specific range (1.05-1.25) to optimize peeling strength and stress distribution. This parameter control, combined with binder content optimization, achieves high adhesion while maintaining manageable battery design parameters.
Solution Approach 2:
The patent applies a moderate aspect ratio (1.05-1.25) that provides sufficient stress distribution improvement without excessive deviation from square geometry. This partial optimization achieves the necessary mechanical performance while avoiding overly complex battery design constraints.
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 design enhances peeling strength and vibration resistance while maintaining high capacity and output, preventing electrode fragility and residual stress, making it suitable for vehicle applications.
Implementation Method 1
a binder for binding an active material used for an active material layer is classified into an organic solvent-based binder and an aqueous binder
Data Source
Figure 1
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Figure 3A~3B
AI summary
[Objet] Provided is a non-aqueous electrolyte secondary battery having high vibration resistance when an aqueous binder is used as a binder for a negative electrode active material. [Solving Means] Disclosed is a flat laminated type non-aqueous electrolyte secondary battery having a power generating element including a positive electrode obtained by forming a positive electrode active material layer on a surface of a positive electrode current collector; a negative electrode obtained by forming a negative electrode active material layer on a surface of a negative electrode current collector; and a separator, in which the negative electrode active material layer includes 2 to 4% by mass of an aqueous binder with respect to the total mass of the negative electrode active material layer, and the negative electrode active material layer has a rectangular shape, wherein a ratio of a length of long side to a length of short side of the rectangle is 1 to 1.25.