Jelly-Roll Electrode Assembly With Folded Separator Overlap at the Core
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Solution Overview
Problem
The repeated contraction and expansion of jelly-roll type electrode assemblies in cylindrical batteries, particularly when using multiple tabs or silicon-based active materials, lead to increased deformation, risking separator damage and internal shorts between the negative and positive electrodes, causing heat generation and ignition.
Innovation Solution
A jelly-roll type electrode assembly design featuring a first and second separator overlapping portion, with the separators arranged in three or more folds at the core part, to prevent deformation-induced damage and internal shorts by altering the bending structure of the separators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a jelly-roll type electrode assembly includes multiple tabs or silicon-based active material to increase capacity, then the battery capacity increases, but the deformation of the electrode assembly at the core part increases causing separator damage and internal short
Solution Approach 1:
The separator is divided into multiple segments including a first separator, a first separator overlapping portion, a second separator, and a second separator overlapping portion. These segmented separator parts are arranged in sequence to provide distributed protection against deformation and internal short, allowing the battery to achieve high capacity while maintaining separator integrity.
Solution Approach 2:
The separator overlapping portions are pre-positioned at the core part of the electrode assembly before winding. This preliminary arrangement ensures that the separators are already in place to prevent deformation and internal short before the electrode assembly undergoes charge-discharge cycles, proactively addressing the reliability issue.
2Duration of action of moving object
If the electrode assembly undergoes repeated contraction and expansion during charge and discharge, then the battery operates normally, but the pressure on the core part increases causing deformation and internal short
Solution Approach 1:
The separator overlapping portions act as cushioning elements positioned beforehand at the core part of the electrode assembly. During repeated contraction and expansion, these overlapping portions absorb and distribute the mechanical stress, preventing deformation and internal short, thus enabling long-term operation while maintaining structural stability.
3Device complexity
If the separator is damaged due to electrode assembly deformation, then the battery structure simplifies, but internal short occurs causing heat generation and ignition
Solution Approach 1:
The separator structure implements local quality enhancement by creating overlapping portions at specific locations (the core part of the electrode assembly). This localized reinforcement provides additional protection against internal short at the most vulnerable area without significantly increasing the overall complexity of the separator structure throughout the entire battery.
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
Disclosed are a jelly-roll type electrode assembly and a secondary battery including the same.