Segmented Electrode Assembly Structure for Stable Current Collection
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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 electrode assembly is divided into multiple segments along the winding direction, with each segment having its own uncoated portion for current collection. This segmentation distributes the current collection points, reducing resistance and heat generation at any single point while maintaining structural simplicity.
Solution Approach 2:
The patent transitions from collecting current at a single tab location to collecting current at multiple locations along the winding axis (adding a dimensional aspect). This multi-point collection approach reduces the current density at each collection point, improving overall current collection efficiency.
2Ease of manufacture
If the uncoated portion is bent irregularly during assembly, then welding becomes difficult, but maintaining perfect alignment increases manufacturing complexity
Solution Approach 1:
The uncoated portion is divided into multiple segments that can be independently positioned and welded. This segmentation allows each segment to be aligned and welded separately, making the welding process more tolerant of minor misalignments while maintaining manufacturing precision.
Solution Approach 2:
The patent optimizes the dimensions and spacing of the segmented uncoated portions to ensure proper alignment during assembly. By carefully controlling the geometric parameters of each segment, the design achieves both ease of welding and manufacturing precision without requiring complex alignment procedures.
3Ease of operation
If the uncoated portion blocks the core during bending, then electrolyte injection is blocked, but preventing blockage requires more complex segment arrangement
Solution Approach 1:
The uncoated portion is segmented and arranged in a specific pattern that creates gaps between segments. These gaps allow electrolyte to flow into the core during injection, preventing blockage while maintaining a relatively simple segment arrangement that is easy to manufacture.
Solution Approach 2:
The segment arrangement follows a repeating pattern along the winding direction, where each segment is positioned to mirror the previous one. This copying approach ensures consistent electrolyte flow paths while simplifying the overall design and manufacturing process.
4Reliability
If multiple segments are arranged radially with optimized dimensions, then current collection efficiency improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the width, length, and spacing parameters of each segment to achieve the best current collection efficiency. By carefully selecting these parameters, the design maximizes electrical contact area while maintaining tolerance ranges that are practical for manufacturing.
Solution Approach 2:
The radial arrangement of multiple segments distributes the current collection function across different angular positions. This segmentation approach improves current collection efficiency by reducing the path length for current flow while the modular nature of segments makes the precision requirements more manageable through standardized manufacturing processes.
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.