Cylindrical Electrode Assembly Segmentation for Low-Resistance Welding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional cylindrical batteries face issues with high resistance and heat generation due to concentrated current flow at the electrode tab, leading to potential ignition during rapid charging, and challenges in electrolyte injection and welding due to irregular bending of uncoated portions, which can cause internal short circuits and block the electrolyte passage.
Innovation Solution
The electrode assembly features a segment structure in the uncoated portions with optimized dimensions and a radial arrangement of segments, allowing for stable welding, reduced resistance, improved electrolyte impregnation, and unobstructed electrolyte passage, with a current collector welded to a broad area for enhanced current collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a strip-shaped electrode tab is used to connect positive and negative electrodes, then the battery structure is simple, but current collection efficiency is poor due to large resistance and heat generation
Solution Approach 1:
The uncoated portion of the current collector is divided into multiple segments along the winding direction, creating multiple independent bending regions. This segmentation distributes the stress during bending and prevents concentration of deformation at a single point, thereby maintaining stable electrical contact and reducing resistance while keeping the overall structure simple.
Solution Approach 2:
The current collector is designed with different properties in different regions: the coated portions maintain structural integrity and electrical connection, while the uncoated segments are designed to be flexible and bendable. This local differentiation allows the battery to accommodate volume changes during charge-discharge cycles while maintaining stable current collection, improving both reliability and current collection efficiency.
2Reliability
If the uncoated portion is bent to improve welding, then welding stability is improved, but irregular bending causes internal short circuits and blocks electrolyte passage
Solution Approach 1:
The uncoated portion is segmented into multiple independent regions that can bend uniformly and predictably. This controlled segmentation ensures that during battery assembly, the segments bend in a regular pattern that maintains proper spacing between electrodes, preventing internal short circuits while allowing stable welding of the current collector to the terminal.
Solution Approach 2:
The current collector is designed with pre-formed uncoated segments that are prepared in advance with specific geometric characteristics. These pre-designed segments are positioned and oriented correctly before battery assembly, ensuring they bend in the intended manner during welding without causing irregular deformations that could lead to short circuits or electrolyte passage blockage.
3Quantity of substance
If the battery form factor is increased for electric vehicle application, then energy capacity is improved, but heat generation increases leading to potential ignition during rapid charging
Solution Approach 1:
The current collector is divided into multiple uncoated segments that create multiple independent current collection paths. This segmentation reduces the current density in each individual path, lowering resistive heating. The segmented structure also improves heat dissipation by distributing heat generation across multiple regions, reducing the risk of thermal runaway during rapid charging of large-capacity batteries for electric vehicles.
Solution Approach 2:
The battery design implements local quality optimization by having uncoated segments at specific locations where heat generation is most critical. These segments provide enhanced current collection and heat dissipation capabilities at key thermal management points, allowing the battery to achieve high energy capacity while maintaining safe operating temperatures during rapid charging.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces internal resistance, increases energy density, prevents internal short circuits, and facilitates easy electrolyte injection and welding, resulting in a cylindrical battery with improved safety and performance.
Implementation Method 1
the current collector is welded to the uncoated portion to improve the current collecting efficiency
Implementation Method 2
the uncoated portion includes a segment region divided into a plurality of independently bendable segments
Implementation Method 3
a radial arrangement of segments, allowing for stable welding, reduced resistance, improved electrolyte impregnation
Data Source
AI summary
In the electrode assembly, the first uncoated portion provided at a long side end of a first electrode includes a segment region divided into a plurality of independently bendable segments by a plurality of cut grooves provided along a winding direction. The segment region includes a plurality of segment groups disposed with a group separation pitch along the winding direction. The plurality of segment groups constitute at least one segment alignment on one side of the electrode assembly. At least some of central points of winding turn arcs where the p number of segment groups are located are not located on a predetermined alignment line extending in the radial direction from the center of the core.