Cylindrical Electrode Assembly With Radial Tabless Current Collection
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Solution Overview
Problem
Conventional cylindrical batteries face issues with current collection efficiency due to concentrated current flow in strip-shaped electrode tabs, leading to high resistance and heat generation, especially when scaled for electric vehicles, and the bending of uncoated portions for tab-less designs complicates electrolyte injection and welding, potentially damaging separators and active material layers.
Innovation Solution
The electrode assembly design includes uncoated portions bent in a radial direction, forming multiple stacked layers to improve current collection efficiency, ensuring unobstructed electrolyte injection paths, and direct welding to current collectors, with specific geometric configurations to prevent damage and maintain structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uncoated portions are bent in radial direction to improve current collection efficiency, then resistance is reduced and energy density is enhanced, but separator and active material layers may be damaged during bending and welding
Solution Approach 1:
The uncoated portion is divided into multiple segments along the winding direction, creating multiple bending lines. This segmentation allows the uncoated portion to bend in a controlled manner without concentrating stress at a single location, thereby preventing damage to the separator and active material layers while maintaining improved current collection efficiency through radial bending.
Solution Approach 2:
Different regions of the uncoated portion are designed with different properties: the uncoated portion itself is made flexible to enable radial bending, while the coated portions (positive and negative electrodes) maintain their structural integrity. The insulating coating is applied specifically at the uncoated portion to prevent short circuits during bending, allowing local adaptation to resolve the contradiction between bending flexibility and structural protection.
2Strength
If uncoated portions are bent radially to form multiple stacked layers, then welding strength to current collectors is improved, but electrolyte injection paths may be obstructed
Solution Approach 1:
The uncoated portion is bent in the radial direction (perpendicular to the winding axis) rather than only in the axial direction. This radial bending creates multiple stacked layers that improve welding strength in the radial dimension while the segmented structure with gaps between segments maintains open pathways in the axial dimension for electrolyte injection, thus resolving the contradiction between enhanced welding strength and unobstructed electrolyte flow.
3Ease of manufacture
If strip-shaped electrode tabs are used for current collection, then manufacturing is simplified, but current collection efficiency is poor due to concentrated current flow and high resistance
Solution Approach 1:
Instead of using strip-shaped tabs that collect current in one dimension (axial direction), the invention utilizes the radial direction by bending the uncoated portion radially to form multiple stacked layers. This transforms the current collection from a one-dimensional strip structure to a multi-layer radial structure, significantly increasing the current collection area and efficiency while maintaining manufacturing simplicity through the winding process.
Solution Approach 2:
The invention merges the current collection function with the electrode structure itself by using the uncoated portion of the current collector as the current collection element. Rather than adding separate tabs, the uncoated portion is directly bent and welded to external current collectors, integrating the current collection pathway into the electrode assembly structure and eliminating the need for additional tab components.
Data Source
AI summary
An electrode assembly, a battery, and a battery pack and a vehicle including the same are provided. In the electrode assembly, a first electrode, a second electrode, and a separator interposed therebetween are wound based on an axis to define a core and an outer circumference. The first electrode includes a first portion coated with an active material and a second portion at a first side and adjacent the first portion, the second portion being exposed beyond the separator along a first axial direction of the electrode assembly. A part of the second portion is bent in a radial direction of the electrode assembly forming a first surface region including stacked layers of the second portion, and in a partial region of the first surface region, a number of the stacked layers of the second portion is 10 or more in the in the first axial direction.