Cylindrical Battery Electrode Assembly for Low-Resistance Current Collection
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Solution Overview
Problem
Conventional cylindrical battery cells face issues with high resistance, heat generation, and internal short circuits due to concentrated current flow at electrode tabs, leading to potential ignition and electrolyte impregnation asymmetry, which affects energy density and safety.
Innovation Solution
The electrode assembly design includes uncoated portions divided into segments with controlled bending and positioning to minimize resistance, ensure uniform electrolyte impregnation, and prevent internal short circuits, using a separator with inorganic particles on both sides for improved heat resistance and impregnation symmetry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If current is concentrated in strip-shaped electrode tabs, then electrical connection is simplified, but resistance increases and heat generation occurs
Solution Approach 1:
The uncoated portion of the electrode plate is divided into multiple segments along the winding direction, with each segment having a different height. This segmentation allows current to be distributed across multiple contact points with the current collecting plate, reducing resistance and heat generation while maintaining structural simplicity
Solution Approach 2:
Different segments of the uncoated portion are designed with varying heights to create localized contact zones at different positions along the winding direction. This ensures uniform current distribution and prevents concentration of current at single points, improving current collection efficiency
2Reliability
If uncoated portion is bent to improve welding, then current collection efficiency improves, but internal short circuit risk increases
Solution Approach 1:
The uncoated portion is pre-bent into segments with controlled heights before assembly, creating a stepped structure that guides the current collecting plate to contact only at safe zones. This preliminary shaping prevents short circuits by ensuring proper alignment and contact geometry before the battery is assembled
Solution Approach 2:
The segmented uncoated portion acts as an intermediary structure between the coated electrode and the current collecting plate. The varying heights create intermediate contact zones that facilitate reliable welding while maintaining electrical insulation through the coating on adjacent segments
3Ease of manufacture
If separator position is not controlled, then manufacturing is simpler, but electrolyte impregnation becomes asymmetric
Solution Approach 1:
The separator is positioned relative to the segmented uncoated portions, with each segment creating a reference zone for separator placement. This segmentation provides natural positioning cues that ensure symmetric electrolyte impregnation without requiring complex positioning mechanisms
Solution Approach 2:
The heights of the segmented uncoated portions are specifically designed to control the position of the separator and guide electrolyte flow. By adjusting the height parameters of different segments, uniform electrolyte distribution is achieved while maintaining simple manufacturing processes
Data Source
AI summary
Disclosed is an electrode assembly, a cylindrical battery cell, and a battery pack and a vehicle including the same. The electrode assembly is a jelly-roll type electrode assembly having a structure in which a first electrode plate and a second electrode plate having a sheet shape and a separator interposed therebetween are wound in one direction, and at least one of the first electrode plate and the second electrode plate includes an uncoated portion, not coated with an active material layer, at a long side end. At least a part of the uncoated portion is used as an electrode tab by itself. In addition, the uncoated portion includes a core-side uncoated portion adjacent to the core of the electrode assembly, a circumferential uncoated portion adjacent to the outer circumferential surface of the electrode assembly, an intermediate uncoated portion interposed between the core-side uncoated portion and the circumferential uncoated portion. Preferably, at least one of the core-side uncoated portion and the circumferential uncoated portion has a relatively smaller height in a winding axis direction than the intermediate uncoated portion.