Jelly-Roll Electrode Assembly With Welded Backup Conduction Path
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Solution Overview
Problem
The existing jelly-roll type electrode assemblies in cylindrical batteries face stress concentration issues on the outermost negative electrode, leading to cracks and deformation during charging and discharging.
Innovation Solution
A jelly-roll type electrode assembly is designed with a disconnection prevention portion on the surface of the first electrode current collector opposite to the surface facing the longitudinal end portion of the second electrode, and a weld portion electrically connecting the first electrode current collector and the disconnection prevention portion, ensuring that both longitudinal end portions of the disconnection prevention portion do not coincide with the longitudinal end portion of the second electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a jelly-roll type electrode assembly with negative electrode-outermost structure is used, then the battery structure is simplified and manufacturing is easier, but stress concentration occurs on the outermost negative electrode leading to cracks and deformation
Solution Approach 1:
The electrode assembly is segmented into multiple layers with alternating positive and negative electrodes, where the positive electrode extends beyond the negative electrode at both ends. This segmentation distributes the mechanical stress away from the outermost negative electrode, preventing crack formation while maintaining the simplified jelly-roll manufacturing process.
Solution Approach 2:
Instead of having the negative electrode as the outermost layer, the patent inverts the traditional structure by making the positive electrode the outermost layer at both ends of the rolled assembly. This inversion relocates the stress concentration points to the positive electrode, protecting the negative electrode from cracking while maintaining structural integrity.
2Quantity of substance
If the positive electrode thickness is increased to improve capacity, then energy storage is improved, but stress concentration on the negative electrode increases leading to cracks
Solution Approach 1:
The electrode assembly uses multiple thin layers of positive and negative electrodes stacked alternately. This segmentation allows the positive electrode to have sufficient total active material quantity while keeping individual layer thicknesses manageable, distributing stress evenly and preventing crack formation on the negative electrode.
Solution Approach 2:
The positive electrode is designed to extend beyond the negative electrode at both ends (excessive action), creating an overlapping structure. This partial extension allows the positive electrode to provide additional active material capacity while the overlapping region distributes mechanical stress, preventing concentration on the negative electrode.
3Reliability
If the electrode assembly structure is modified to prevent stress concentration, then electrode integrity is improved, but device complexity increases
Solution Approach 1:
The patent applies a simple structural inversion where the positive electrode is made the outermost layer instead of the negative electrode. This single design change prevents stress concentration on the negative electrode without requiring complex additional components or manufacturing steps, maintaining simplicity while improving reliability.
Solution Approach 2:
The positive electrode serves multiple functions: it provides active material for energy storage and simultaneously acts as a protective outer layer that absorbs mechanical stress. This multi-functionality prevents negative electrode cracking without adding separate protective components, avoiding increased device complexity.
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
The inclusion of the disconnection prevention portion and the weld portion effectively prevents cracks and deformation due to stress concentration on the outermost negative electrode, while also providing an additional conductive passage to suppress resistance increase and improve battery stability even in the event of disconnection.
Implementation Method 1
a weld portion electrically connecting the first electrode current collector and the disconnection prevention portion
Data Source
AI summary
A jelly-roll type electrode assembly includes a disconnection prevention portion, whereby it is possible to prevent crack and deformation of the electrode assembly. The disconnection prevention portion is electrically connected to a first electrode current collector via a weld portion to provide an additional conductive passage, so it is possible to suppress an increase in resistance and improve battery stability even in the event of disconnection. The jelly-roll type electrode assembly can prevent local problems such as reduction in roundness and lithium precipitation due to formation of additional steps by adjusting positions of the disconnection prevention portion and the weld portion, and can minimize occurrence of additional cracks and deformation of the electrode assembly due to formation of fixed points. A secondary battery including the same is also provided.