Cylindrical Cell Jellyroll With Slotted Edges for Low-Heat Connection
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Solution Overview
Problem
Conventional methods for manufacturing cylindrical electrochemical cells face issues such as high localized ohmic heating, reduced Ah capacity due to uncoated regions, increased manufacturing complexity, and higher costs. Additionally, methods like blind through welding and mechanical compression suffer from production yield loss, electrical shorts, and degradation of contact resistance over time.
Innovation Solution
The solution involves forming first and second electrode sheets with uncoated conductive edges and coated opposing surfaces, wound around a cylindrical core to create a jellyroll structure. Slotted cutouts are cut from the uncoated edges, angularly co-located relative to the cylindrical core, allowing for consolidation and electrical connection without discrete tabs, thereby reducing manufacturing costs and improving performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discrete tabs are attached to electrode substrate foil at several points along the electrode length, then electrical connection is provided, but localized ohmic heating occurs at tab areas
Solution Approach 1:
The electrode assembly is divided into multiple discrete tabs attached at different points along the electrode length, distributing the electrical connection points to reduce localized current density and ohmic heating at any single location
Solution Approach 2:
Different regions of the electrode are treated differently - tab areas have removed coating to expose conductive substrate for electrical connection, while other areas maintain coating for electrochemical function, creating localized electrical pathways without affecting overall electrode performance
2Reliability
If coating is removed from electrode regions for tab attachment, then electrical connection is enabled, but Ah capacity is reduced due to uncoated regions
Solution Approach 1:
The electrode structure implements local quality differentiation where specific regions have removed coating to create conductive tabs for electrical connection, while the majority of the electrode surface retains coating to maintain electrochemical active material and Ah capacity
Solution Approach 2:
The electrode is segmented into active coated regions for energy storage and uncoated tab regions for electrical connection, allowing simultaneous optimization of both capacity and electrical connectivity
3Reliability
If multiple discrete tab attachment operations are performed, then electrical connection is achieved, but manufacturing complexity increases
Solution Approach 1:
The manufacturing process is segmented into distinct operations - coating removal at specific locations, tab formation, and sequential welding operations - allowing each step to be optimized and controlled independently while maintaining overall process manageability
4Reliability
If blind through welding is used to connect electrodes, then electrical connection is provided, but metal particles are deposited into jellyroll assembly causing yield loss
Solution Approach 1:
The harmful byproduct (metal particles) is extracted or prevented from entering the sensitive jellyroll assembly by performing welding operations outside the sealed cell structure, then assembling the welded components into the final device, thereby protecting the internal assembly from contamination
5Reliability
If mechanical compression is used to hold plate against uncoated electrode foil edges, then electrical connection is provided, but contact resistance degrades over time
Solution Approach 1:
The mechanical compression system is replaced with a welding-based electrical connection system that creates a metallurgical bond between the plate and electrode foil, eliminating the time-dependent contact resistance degradation associated with mechanical pressure and oxidation
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
This approach enhances electrical and thermal performance by reducing electrical resistance and avoiding localized heating, while also lowering manufacturing costs through simplified processes and reduced equipment complexity. The method allows for high-speed automated assembly and increased cell reliability by minimizing discrete welds.
Implementation Method 1
consolidating the first and second electrodes to electrically connect the first and second electrodes to first and second terminals
Implementation Method 2
electrical current may be channeled to a small area of the tabs at discrete points along the electrode, creating areas that may operate at significantly higher temperature than the remainder of the electrode due to high localized ohmic heating
Data Source
AI summary
An electrochemical storage cell may comprise first and second electrode sheets wound around a cylindrical core forming a jellyroll structure, the first and second electrode sheets each comprising uncoated conductive edges parallel to end faces of the jellyroll structure, and coated opposing surfaces between the uncoated conductive edges, first and second separator sheets mechanically and electrically separating the coated opposing surfaces of the first and second electrode sheets and mechanically and electrically separating the cylindrical core and the coated opposing surfaces of the first electrode sheet, and slotted cutouts from the uncoated conductive edges, the slotted cutouts angularly co-located relative to the cylindrical core upon forming the jellyroll structure.