Z-Fold Electrode Assembly Layout to Prevent Separator Overhang
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Solution Overview
Problem
In Z-folding type electrode assemblies, the overhang phenomenon occurs when the positive electrode deviates from the negative electrode, leading to alignment issues, performance degradation, and increased risk of short circuits due to the excessive wrapping of the separator sheet around the electrodes.
Innovation Solution
The electrodes and separator sheet portions are alternately stacked in a Z-folding type configuration, with specific spacing and folding patterns to ensure the positive electrode does not deviate from the negative electrode, using a zigzag-shaped separator sheet that maintains appropriate separation distances and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the separator sheet is designed to wrap the electrode with excessive length, then the electrode assembly can be manufactured with high degree of alignment and electrolyte impregnation, but the positive electrode deviates from the negative electrode causing overhang and alignment disturbance
Solution Approach 1:
The patent changes the geometric parameters of the electrode assembly by making the positive electrode shorter than the negative electrode and creating specific spacing relationships. The separator sheet length is controlled to be greater than the negative electrode length but the positive electrode is designed with reduced length, transforming the dimensional parameters to prevent overhang while maintaining manufacturing alignment.
Solution Approach 2:
The patent introduces asymmetry in the electrode configuration by making the positive electrode shorter than the negative electrode. This asymmetric design breaks the symmetry that would otherwise cause the positive electrode to overhang, creating a balanced structure where the separator sheet can wrap without causing deviation or misalignment.
2Reliability
If the positive electrode is designed to have smaller area than the negative electrode, then overhang can be prevented, but the separator sheet portion still greatly exceeds the electrodes causing potential alignment issues
Solution Approach 1:
The patent controls the separator sheet length parameter to be greater than the negative electrode length but ensures the positive electrode length is shorter. This parameter configuration allows the separator to wrap the electrodes properly while the shorter positive electrode prevents overhang, achieving both reliability and manufacturing precision.
Solution Approach 2:
The patent performs preliminary design of the electrode dimensions before assembly, pre-determining the positive electrode to be shorter than the negative electrode and calculating the appropriate separator length. This preliminary configuration ensures that during the Z-folding manufacturing process, the electrodes maintain proper alignment without overhang.
3Productivity
If electrodes and separator sheet are stacked in Z-folding type, then high degree of electrolyte impregnation is achieved, but the separator sheet greatly exceeds the electrodes increasing the risk of short circuits
Solution Approach 1:
The patent changes the dimensional parameters of the electrode assembly in the Z-folding configuration. By making the positive electrode shorter than the negative electrode and controlling the separator length, the patent ensures that the separator wraps the electrodes adequately for electrolyte impregnation while preventing excessive extension that could cause short circuits between electrodes.
Data Source
AI summary
An electrode assembly includes alternately stacked electrodes and separator sheet portions of a separator sheet. The electrodes include a first and second electrodes. The separator sheet has a zigzag shape. The second electrode is shorter than the first electrode. A side surface wrapped by the separator sheet between opposing side surfaces of the first electrode and a side surface wrapped by the separator sheet between opposing side surfaces of the second electrode are respectively spaced apart from the separator sheet. An opposite side surface between the opposing side surfaces of the first electrode protrudes further than the separator sheet from the side surface of the second electrode. A separation distance between the separator sheet and the side surface of the second electrode is equal to or shorter than a distance by which the first electrode protrudes further than the second electrode from the side surface of the second electrode.