Segmented Electrode Assembly for Cylindrical Battery Current Collection
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Solution Overview
Problem
Conventional cylindrical batteries face issues with current collection efficiency, heat generation, and electrolyte injection due to concentrated current flow at electrode tabs, leading to potential short circuits and increased resistance, which are exacerbated in larger form factors.
Innovation Solution
The electrode assembly features a segmented uncoated portion with an insulating layer and controlled bending to prevent deformation, ensuring stable welding and electrolyte impregnation, while minimizing resistance and preventing short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If current is concentrated in the strip-shaped electrode tab, then the battery structure is simple, but the current collection efficiency is poor due to large resistance and large heat generation
Solution Approach 1:
The electrode tab is segmented into multiple sub-tabs by forming cut grooves along the winding axis direction. This divides the single concentrated current path into multiple parallel paths, reducing current density and resistance at each connection point while improving overall current collection efficiency
Solution Approach 2:
The cut grooves are formed in the axial direction (parallel to winding axis) rather than radial direction, creating segments that extend along the length of the electrode assembly. This dimensional approach increases the effective surface area for current collection without complicating the radial battery structure
2Reliability
If the uncoated portion is bent to improve welding, then current collection efficiency improves, but the uncoated portion may be deformed causing internal short circuit
Solution Approach 1:
Dividing the uncoated portion into segmented structures with cut grooves creates natural bending zones that control deformation. The segments can bend independently at the groove locations, distributing stress and preventing catastrophic deformation that would cause short circuits
Solution Approach 2:
The insulating layer is introduced as an intermediary between the uncoated portion and the separator. This layer provides electrical insulation that prevents short circuits even when the uncoated portion deforms, while still allowing the bending to proceed for improved welding contact
3Reliability
If the uncoated portion is bent toward the core, then welding stability improves, but the cavity may be blocked preventing electrolyte injection
Solution Approach 1:
The segmented structure with cut grooves allows the uncoated portion to bend in a controlled manner that maintains spacing from the core. The segments can articulate at the groove locations, providing welding stability without completely blocking the cavity space needed for electrolyte injection
Solution Approach 2:
The insulating layer is applied specifically to the uncoated portion that contacts the separator, providing localized electrical insulation. This allows the bending to proceed for welding stability while the insulating layer prevents short circuits, and the segmented structure maintains adequate cavity space for electrolyte injection
Data Source
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AI summary
Disclosed is an electrode assembly, a battery, and a battery pack and a vehicle including the same. One end of the electrode assembly includes a plurality of segment alignments in which the plurality of segment groups are aligned along a radial direction, and an electrolyte impregnation portion provided between segment alignments adjacent in a circumferential direction, wherein an end of the first active material portion is exposed between winding turns of the separator. The segments included in the segment alignment are bent toward the core to form a bending surface region. An end of the separator is spaced apart from a criterion line extending in a winding axis direction along a location corresponding to the plurality of cut grooves by 30% or less of a minimum height of the segments forming the bending surface region.