Intermediate Layer for Battery Electrode Adhesion
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Solution Overview
Problem
Lithium ion secondary batteries experience increased internal resistance due to the repeated expansion and contraction of active material particles during charge-discharge cycles, leading to partial separation of the active material layer from the electrode substrate.
Innovation Solution
Incorporating an intermediate layer between the electrode substrate and the active material layer, containing a binder and a conductive aid, which allows active material particles to enter and be in contact with the substrate, preventing separation during cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the positive active material layer is compressed to increase active material density, then the active material density is improved, but the particles abutted against the electrode substrate move away during charge-discharge cycles, causing separation
Solution Approach 1:
An intermediate layer is introduced between the positive active material layer and the electrode substrate. This intermediate layer acts as a mediator that prevents direct contact between the active material particles and the substrate, thereby preventing separation during charge-discharge cycles while maintaining high active material density. The intermediate layer absorbs the mechanical stress and volume changes of the active material particles.
Solution Approach 2:
The physical and chemical parameters of the interface between the active material layer and electrode substrate are changed by introducing the intermediate layer. This layer has specific properties (porosity, adhesion, mechanical strength) that differ from both the active material and substrate, creating an optimized interface that maintains both density and adhesion.
2Reliability
If an intermediate layer is introduced between the active material layer and electrode substrate, then the separation is prevented, but the device structure becomes more complex
Solution Approach 1:
The intermediate layer is designed with a porous structure that allows it to be thin yet effective. The porous structure provides high surface area for adhesion while maintaining flexibility to accommodate volume changes of active material particles, preventing separation without requiring a thick layer that would significantly increase complexity.
Solution Approach 2:
The intermediate layer is formed as a composite material combining multiple components (binder, conductive aid, and optional active material) that work synergistically. This composite structure provides both mechanical adhesion and electrical conductivity, achieving multiple functions in a single layer to minimize structural complexity.
Data Source
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AI summary
An energy storage device includes an electrode having an electrode substrate; an active material layer which is disposed to cover a surface of the electrode substrate and which contains active material particles; and an intermediate layer which is disposed between the electrode substrate and the active material layer and which contains a binder, wherein the active material particles of the active material layer enter the intermediate layer, and are in contact with the electrode substrate and the intermediate layer.