Secondary Battery Electrode Tab Cutout for Crack Prevention
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Solution Overview
Problem
The challenge is to prevent wrinkles, curvature, and cracking in secondary battery electrode plates due to differences in length between the active material layer and substrate exposed portions during compression, especially when the packing density of the active material layer exceeds 3.58 g/cm3 and the tab portion width is 10 mm or more, which affects the reliability and electric resistance of the battery.
Innovation Solution
A method involving a cutout forming step to create cutouts at the base of the tab portion where the active material layer is formed, followed by a compressing step to increase the packing density of the active material layer, thereby releasing strain and preventing cracks at the tab portion base.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the active material layer is compressed with a stronger force to increase packing density, then the energy density of the secondary battery is improved, but wrinkles are generated in the substrate and the electrode plate becomes curved
Solution Approach 1:
The substrate exposed portion is divided into multiple segments by providing cutouts at regular intervals. This segmentation allows the substrate to be divided into multiple independent regions that can accommodate compression-induced length differences independently, preventing wrinkle formation and maintaining electrode plate flatness during strong compression treatment.
Solution Approach 2:
Cutouts are provided in the substrate exposed portion before the compression treatment is applied. This preliminary action creates predetermined release points that prevent strain accumulation during subsequent compression, allowing the electrode plate to withstand stronger compression forces without deforming.
2Quantity of substance
If the active material layer is compressed with a stronger force to increase packing density, then the amount of active material in the battery case is increased, but cracks are generated in the electrode plate
Solution Approach 1:
The substrate exposed portion is segmented into multiple independent regions by cutouts, which prevents crack propagation across the entire electrode plate. When compression is applied, any cracks that form are confined to individual segments between cutouts, maintaining overall structural integrity and reliability of the electrode plate.
Solution Approach 2:
Cutouts are created in advance before compression treatment, establishing predetermined weak points that act as strain release zones. This preliminary action prevents uncontrolled crack formation during compression by providing designated locations where strain can be released, thereby maintaining electrode plate integrity.
3Shape
If the substrate exposed portion is elongated to prevent wrinkles during compression, then the flatness of the electrode plate is maintained, but the manufacturing process becomes more complex
Solution Approach 1:
Instead of elongating the entire substrate exposed portion, the invention segments it into multiple smaller regions using cutouts. This approach achieves the same wrinkle-prevention effect as elongation but with a simpler manufacturing process, as cutting is more straightforward than precise elongation control.
Solution Approach 2:
The cutouts are provided in advance before compression treatment, similar to the elongation approach. However, this preliminary action involves a simpler operation (cutting) compared to elongation, reducing manufacturing complexity while achieving the same goal of maintaining electrode plate flatness during compression.
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
This approach enhances the reliability of secondary batteries by preventing cracks and maintaining low electric resistance, ensuring a more reliable and efficient energy storage solution.
Implementation Method 1
providing at least one cutout in a region of each first electrode plate that is at the base of the tab portion and in which the active material layer is formed
Implementation Method 2
a compressing step of compressing the active material layer after the cutout forming step
Data Source
AI summary
Provided is a method for manufacturing a secondary battery including a stacked electrode body including a plurality of positive electrode plates (1) and a plurality of negative electrode plates, the positive electrode plates (1) each having a positive electrode active material layer (1b) formed on a positive electrode substrate (1a), a positive electrode substrate exposed portion where the positive electrode active material layer (1b) is not formed on the positive electrode substrate (1a) being provided as a positive electrode tab portion (1e) at the end of the positive electrode plate (1). The method includes a cutout forming step of providing a cutout in a region at the base of the positive electrode plate (1) where the active material layer (1b) is formed, and a compressing step of compressing the positive electrode active material layer (1b) after the cutout forming step.