Li-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 uneven thickness due to notches, leading to lithium precipitation during the cycling process, as the notch causes an increase in impedance and gap between the separator and the electrode.
Innovation Solution
A positive electrode design with notches on opposite sides for tab welding, where the notch dimension is optimized to ensure proper tab arrangement and welding, reducing uneven thickness and impedance, and minimizing lithium precipitation risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a notch is punched on the positive electrode 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 optimizes the notch dimensions by defining specific parameter ranges: the notch width W1 is 2-12mm, the notch length L1 is 8-30mm, and the distance from the notch to the electrode edge is 2-12mm. These parameter changes allow the notch to be small enough to avoid severe thickness unevenness and lithium precipitation, while still being large enough to remove residual material and enable proper electrode formation and bonding.
2Reliability
If the notch dimension is reduced to minimize thickness unevenness, then lithium precipitation is reduced, but the tab welding area may be insufficient
Solution Approach 1:
The patent defines optimized parameter ranges that balance thickness uniformity and welding capability: the notch width W1 is limited to 2-12mm to maintain thickness uniformity, while the notch length L1 is set to 8-30mm to provide sufficient welding area. The distance from the notch to the electrode edge is also optimized to 2-12mm, ensuring both uniform thickness and adequate welding space.
3Ease of manufacture
If the cleaning region is enlarged to improve tab welding, then the welding area is sufficient, but the electrode thickness becomes more uneven
Solution Approach 1:
The patent optimizes the cleaning region dimensions by setting the notch width W1 to 2-12mm and the notch length L1 to 8-30mm. These parameter changes ensure that the cleaning region is large enough to provide sufficient tab welding area while being constrained to minimize thickness unevenness and maintain manufacturing precision.
Data Source
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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.