Lithium-Ion Positive Electrode Notch Layout for Stable Tab Welding
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Solution Overview
Problem
The existing manufacturing process for lithium-ion battery positive electrodes results in notches that cause uneven thickness, leading to lithium precipitation during the cycling process due to increased impedance and gap enlargement between the separator and the positive electrode.
Innovation Solution
A positive electrode design with opposite cleaning regions and notches on the sides, where the notch penetrates the electrode in the thickness direction, allowing a matching part of the tab to be provided within the notch, with specific dimensions for D1, D2, and the notch shape to ensure proper welding and reduce uneven thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a notch is punched on the tab groove to remove residual material region, then the electrode can be properly formed and bonded, but the notch causes uneven thickness at the edges of the square battery which leads to lithium precipitation during cycling
Solution Approach 1:
The patent applies local quality by creating a transition zone with gradual thickness change instead of an abrupt notch. The cleaning region is designed with specific dimensions (D1=8-30mm, D2=4-29mm, D1>D2) to provide a gradual transition from the electrode body to the tab groove area, maintaining local structural integrity while still allowing proper material removal for welding.
Solution Approach 2:
The patent uses asymmetry by designing the cleaning region with non-uniform dimensions where D1 (dimension at edge of cleaning region) is greater than D2 (maximum dimension of notch). This asymmetric design creates a gradual thickness transition rather than a symmetric abrupt notch, preventing the uneven thickness that causes lithium precipitation while maintaining the necessary material removal for proper electrode formation.
2Reliability
If the notch dimension is reduced to minimize uneven thickness, then lithium precipitation is prevented, but the cleaning region may become insufficient for proper tab welding
Solution Approach 1:
The patent applies parameter changes by optimizing the dimensions of the cleaning region (D1=8-30mm, D2=4-29mm) to achieve a balance between maintaining sufficient welding area and minimizing uneven thickness. By controlling the ratio and absolute values of these parameters, the design ensures both reliable tab welding and reduced risk of lithium precipitation during battery cycling.
Data Source
AI summary
A positive electrode for a lithium-ion battery is provided. Opposite cleaning regions are provided respectively on opposite sides of the positive electrode in a thickness direction thereof for welding with a welding end of a tab. A notch is formed on a side of the cleaning regions close to an edge of the positive electrode in a width direction thereof. The notch penetrates the positive electrode in the thickness direction and a part of the tab which is corresponding to the notch in a width direction of the positive electrode is a matching part, the matching part is enabled to be provided in the notch. D1 is greater than D2, where D1 represents a dimension of a part of the cleaning regions intersecting an edge of the notch in a length direction of the positive electrode, and D2 represents a maximum dimension of the notch in the length direction.