Negative Electrode Coating Structure for Battery Adhesion Balance
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Solution Overview
Problem
The adhesion force between the negative electrode active material and the current collector in secondary batteries is relatively low, leading to delamination issues during cycling.
Innovation Solution
A negative electrode plate design that includes a metal foil with a conductive coating sandwiched between the active material layer and the metal foil surface, with specific thickness and roughness conditions to enhance adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the negative electrode active material is directly applied to the current collector surface, then the manufacturing process is simple, but the adhesion force is low causing electrode plate delamination
Solution Approach 1:
A conductive coating layer is introduced as an intermediary between the metal foil and the active material layer. This intermediate layer enhances adhesion force while maintaining manufacturing simplicity, resolving the contradiction between ease of manufacture and reliability.
Solution Approach 2:
The negative electrode plate is constructed as a composite structure with multiple layers (metal foil, conductive coating, active material layer). This composite approach improves adhesion force through the conductive coating while keeping the overall manufacturing process straightforward.
2Reliability
If the conductive coating thickness is increased to improve adhesion, then the adhesion force increases, but the volumetric energy density decreases
Solution Approach 1:
The thickness of the conductive coating is optimized to a specific range (0.3-4.5 μm) to achieve the best balance between adhesion force and volumetric energy density. This parameter optimization resolves the contradiction by finding the optimal value that satisfies both requirements.
Solution Approach 2:
Instead of using a thick conductive coating for maximum adhesion, a thin coating within the optimal thickness range is applied, providing sufficient adhesion force while minimizing the impact on volumetric energy density.
3Reliability
If the surface roughness is increased to enhance coating adhesion, then the adhesion force improves, but the manufacturing precision requirements increase
Solution Approach 1:
The surface roughness of the metal foil is optimized to a specific range to enhance adhesion force while avoiding excessive manufacturing precision requirements. This parameter optimization resolves the contradiction between reliability and manufacturing precision.
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 enhanced adhesion force reduces the risk of the active material layer falling off, while maintaining sufficient volumetric energy density and improving the battery's impact resistance and safety performance.
Implementation Method 1
The adhesion force between the negative electrode active material and the current collector is relatively low, easily causing the problem of electrode plate delamination
Data Source
AI summary
A negative electrode plate, a secondary battery, and an electronic apparatus are provided. The negative electrode plate includes a metal foil, a first conductive coating, and a first active material layer. The metal foil includes a first surface. The first conductive coating is applied on the first surface. The first active material layer is disposed on a surface of the first conductive coating facing away from the first surface. A thickness of the first conductive coating is h, and ten-point average roughness of the first surface is Rz1, satisfying 0.5≤Rz1/h≤0.8.