Jelly-Roll Electrode Assembly With Core Separator Overlap
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Solution Overview
Problem
The thinning of separators in jelly-roll type electrode assemblies for high-capacity designs leads to weakened physical strength, increased deformation risk during contraction/expansion, and potential internal short-circuits due to damage between negative and positive electrodes.
Innovation Solution
A jelly-roll type electrode assembly design featuring a first and second separator overlapping portion, strategically placed on the surfaces of the second electrode, to enhance the bending and overlapping structure of the separators at the core part, thereby preventing damage and internal short-circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the separator thickness is decreased for high-capacity designs, then the battery capacity increases, but the physical strength of the separator becomes weaker and deformation risk increases
Solution Approach 1:
The patent applies beforehand cushioning by creating an overlapping portion of the separator at the core part of the electrode assembly before any deformation occurs. This overlapping structure acts as a preventive measure that cushions against future deformation and damage during battery operation, allowing the use of thinner separators without compromising strength.
Solution Approach 2:
The patent applies local quality by concentrating the separator overlapping structure specifically at the core part of the electrode assembly where the winding center is located. This is the region that experiences the most significant stress and deformation during battery operation. By reinforcing only this critical local area rather than the entire separator, the design maintains high capacity while providing targeted strength enhancement.
2Quantity of substance
If the separator thickness is decreased, then the battery capacity increases, but the possibility of separator damage and internal short-circuit increases
Solution Approach 1:
The overlapping separator structure is created in advance to prevent future damage. This preventive structure ensures that even if the thin separator is subjected to deformation stresses during battery operation, the overlapping portion at the core part provides a backup barrier that prevents electrode contact and internal short-circuits.
Solution Approach 2:
The separator overlapping portion acts as an intermediary protective layer at the core part of the electrode assembly. When the thin separator is damaged or deformed, this overlapping structure serves as a mediator that prevents direct contact between the positive and negative electrodes, thereby maintaining reliability despite the use of thinner separators for high capacity.
3Quantity of substance
If multiple tabs or silicon-based active materials are added to increase capacity, then the battery capacity increases, but the pressure acting on the core part of the electrode assembly greatly increases
Solution Approach 1:
The patent applies local quality by specifically reinforcing the separator at the core part of the electrode assembly where tabs and silicon-based active materials create concentrated pressure. The overlapping structure is located precisely where the winding center is, which is the region experiencing the most significant stress from multiple tabs and silicon expansion during charging cycles.
Solution Approach 2:
The overlapping separator structure is created beforehand to cushion against the increased pressure from multiple tabs and silicon-based active materials. This preventive reinforcement ensures that when high capacity designs with multiple tabs and silicon are implemented, the core part of the electrode assembly has enhanced structural support to withstand the resulting stresses.
Data Source
AI summary
A jelly-roll type electrode assembly includes a first electrode, a first separator, a second electrode, and a second separator sequentially stacked and wound. The jelly-roll type electrode assembly includes a winding axis and a core part and the second electrode has a first surface and a second surface. The first surface is disposed to face the winding axis of the jelly-roll type electrode assembly and the second surface is disposed opposite to the first surface. The core part includes a first separator overlapping portion and a second separator overlapping portion. The first separator overlapping portion is provided on the first surface of the second electrode and the second separator overlapping portion is provided on the second surface of the second electrode. A secondary battery including the same is also provided.