Jelly-Roll Electrode Assembly With Folded Separator Overlap
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Solution Overview
Problem
Cylindrical batteries face issues with separator damage and internal shorts due to the contraction and expansion of electrodes, particularly when using multiple tabs or silicon-based active materials, leading to potential heat generation and ignition.
Innovation Solution
A jelly-roll type electrode assembly design with a separator overlapping portion comprising three or more folds, where the first and second separators have specific friction coefficients and coating layers to control bending and prevent electrode sliding, thereby protecting the negative electrode and separator from deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a coin-type battery structure is used, then the battery can be manufactured with simple processes, but the battery occupies large space and has low volumetric energy density
Solution Approach 1:
The battery is divided into multiple coin-type battery units (first, second, third, and fourth battery units) that are stacked vertically. Each unit contains its own electrodes, separator, and seal structure, allowing independent manufacturing while achieving compact vertical integration. This segmentation enables simple manufacturing processes for each unit while improving overall volumetric energy density through vertical stacking.
Solution Approach 2:
The invention transitions from a single-plane coin-type battery structure to a three-dimensional stacked configuration. By arranging multiple battery units vertically along the height direction, the design maintains the simple manufacturing advantages of coin-type batteries while significantly improving volumetric energy density through vertical space utilization.
2Volume of moving object
If a cylindrical battery structure is used, then the battery has high volumetric energy density, but the battery requires complex winding processes and has difficulty in mass production
Solution Approach 1:
Instead of using a single complex cylindrical structure requiring winding processes, the invention segments the battery into multiple simple coin-type units. Each unit uses straightforward electrode stacking without winding, simplifying manufacturing while achieving high volumetric energy density through vertical integration of multiple units.
Solution Approach 2:
The invention inverts the conventional approach by stacking multiple simple coin-type batteries vertically rather than using a single complex cylindrical structure. This inversion maintains manufacturing simplicity while achieving the volumetric energy density benefits associated with cylindrical designs.
3Strength
If the aluminum foil current collector has large thickness, then the mechanical strength is sufficient, but the battery capacity is reduced due to increased dead weight
Solution Approach 1:
The invention optimizes the thickness parameter of the aluminum foil current collectors to achieve the minimum required mechanical strength while minimizing dead weight. The first and second current collectors have thickness of 6-12 μm, while the third and fourth current collectors have thickness of 3-6 μm, balancing mechanical integrity with capacity maximization.
Solution Approach 2:
Different current collectors are assigned different thicknesses based on their specific structural requirements. The first and second current collectors (6-12 μm) support the main electrode structures, while the third and fourth current collectors (3-6 μm) have reduced thickness where less mechanical strength is needed, optimizing the balance between strength and capacity.
4Ease of manufacture
If the jelly roll structure is used without external shorting prevention, then the manufacturing is simpler, but the battery may experience external shorting during assembly causing safety issues
Solution Approach 1:
The invention implements preliminary protective actions by designing the seal structure to extend beyond the electrode assembly boundaries and by positioning current collectors to overlap with adjacent units. These preliminary measures prevent external shorting during assembly before the battery is fully operational, maintaining both manufacturing simplicity and safety.
Solution Approach 2:
The seal structure acts as a protective barrier that extends beyond the electrode assembly, providing beforehand cushioning against potential external shorting. This protective design prevents direct contact between current collectors of adjacent units during assembly, ensuring safety without complicating the manufacturing process.
Data Source
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AI summary
The present invention provides a jelly-roll type electrode assembly and a secondary battery including the same.