Zigzag Electrode Assembly Layout to Prevent Positive Electrode Exposure
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Solution Overview
Problem
Existing electrode assemblies for medium- and large-sized lithium secondary batteries face challenges in productivity, safety, and energy density due to alignment defects, material deintercalation, and structural weaknesses, particularly in zigzag type assemblies.
Innovation Solution
An electrode assembly design where a negative electrode with separators on both surfaces is bent in a zigzag shape, with multiple positive electrodes inserted inside, ensuring a controlled variation in separation distances of end portions to enhance rigidity and prevent exposure, thereby improving safety and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional zigzag type electrode assembly is used, then the structure allows for medium- and large-sized battery applications, but the rigidity of the electrode assembly is difficult to secure and energy density is low
Solution Approach 1:
The electrode assembly is divided into multiple segments with positive electrodes and negative electrodes stacked alternately with separators, forming a segmented structure that improves rigidity while maintaining flexibility for medium- and large-sized battery applications
Solution Approach 2:
Multiple positive electrodes and negative electrodes are nested within each other in an alternating stacked configuration, with each electrode type inserted inside the structure formed by the other, creating a compact nested arrangement that enhances both rigidity and space utilization for higher energy density
2Ease of manufacture
If the positive electrode is out of an outermost side of the negative electrode in a stack-type electrode assembly, then the structure allows for electrode assembly formation, but lithium ions may be precipitated at an outermost side and alignment defects are generated
Solution Approach 1:
The design ensures that at the outermost side of the electrode assembly, the positive electrode is positioned within the negative electrode structure rather than extending beyond it, creating a localized quality improvement that prevents lithium ion precipitation and alignment defects while maintaining ease of assembly formation
Solution Approach 2:
The electrode assembly is designed with predetermined positioning of positive and negative electrodes during the stacking process, ensuring proper alignment is established before final assembly completion, which prevents alignment defects and lithium ion precipitation issues
3Ease of manufacture
If the separator is stacked in a single-layer structure at an end portion of a side surface, then the structure simplifies manufacturing, but the side surface may be easily damaged and active material may be deintercalated
Solution Approach 1:
The separator structure is designed with enhanced multi-layer configuration at critical end portions and side surfaces where damage risk is highest, while maintaining simpler single-layer structure in less critical areas, thus improving side surface durability without significantly complicating overall manufacturing
Solution Approach 2:
The electrode assembly design incorporates protective structural features at end portions and side surfaces that provide beforehand cushioning against external impacts, preventing damage to the separator and preventing active material deintercalation before such damage can occur
Data Source
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AI summary
The present technology relates to an electrode assembly, of which rigidity may be improved by having a structure in which a negative electrode having separators disposed on both surfaces thereof is bent in a zigzag shape, and a plurality of positive electrodes are individually inserted inside separators bent together with the negative electrode, thereby realizing high safety of the battery. Further, the electrode assembly of the present invention may prevent an end portion of an inserted positive electrode from being exposed by realizing a variation between a separation distance of an end portion of any positive electrode and a separation distance of an end portion of a positive electrode adjacent to the positive electrode with respect to a side surface including the bent structure of the negative electrode at a predetermined ratio, so that the safety of the battery can be improved and also a unit area of the inserted positive electrode can be increased, thereby improving energy density of battery.