Jelly-roll Battery Tab Integration via Copper Foil Folding
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Solution Overview
Problem
Conventional lithium secondary batteries face issues with deformation due to the use of nickel electrode tabs on copper foil electrodes, leading to increased material costs and internal resistance, as well as adhesiveness problems during winding.
Innovation Solution
Incorporating the electrode tab into the current collector by cutting and folding a portion of the electrode current collector, eliminating the need for a separate tab and reducing material costs while preventing deformation and internal resistance increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nickel electrode tabs are used on copper foil electrodes, then electrical connection is achieved, but deformation occurs and internal resistance increases
Solution Approach 1:
The patent merges the electrode tab function with the current collector by cutting and folding a portion of the current collector itself to form the tab, eliminating the need for separate nickel tabs. This integration ensures that the tab and current collector move together as one piece, preventing relative deformation while maintaining electrical connection.
Solution Approach 2:
The patent uses the same material (copper foil) for both the current collector and the electrode tab, ensuring homogeneous material properties throughout. This eliminates the material mismatch between nickel tabs and copper foil that causes deformation, while maintaining adequate electrical conductivity through the copper tab design.
2Reliability
If separate nickel tabs are attached to current collectors, then electrical connection is established, but material costs increase
Solution Approach 1:
The patent combines the current collector and electrode tab into a single integrated component made from one piece of copper foil. This eliminates the need for separate nickel tab materials and the welding process, reducing material costs while maintaining electrical connection functionality.
Solution Approach 2:
The current collector serves dual functions: it collects current from the electrode active material and provides the electrode tab for external electrical connection. This multi-functionality eliminates the need for separate tab components, reducing material usage and cost.
3Reliability
If separate nickel tabs are welded to current collectors, then electrical connection is achieved, but internal resistance increases
Solution Approach 1:
The patent integrates the tab and current collector as one continuous copper foil structure, eliminating the welding interface that creates high contact resistance. The seamless integration ensures low electrical resistance throughout the current collection path.
4Reliability
If different metals are used for tabs and current collectors, then electrical connection is established, but deformation occurs during charge-discharge
Solution Approach 1:
The patent uses homogeneous copper foil material for both the current collector and electrode tab, ensuring uniform thermal and mechanical expansion characteristics. This eliminates the dimensional mismatch and deformation that occurs when dissimilar metals with different expansion coefficients are bonded together during charge-discharge cycling.
Data Source
AI summary
A jelly-roll type battery unit, a winding method thereof and a lithium secondary battery comprising the battery unit include a first electrode plate having a first electrode current collector with a first electrode tab and a first electrode active material layer coated on at least one surface of the first electrode current collector, a second electrode plate having a second electrode current collector with a second electrode tab and a second electrode active material layer coated on at least one surface of the second electrode current collector, and a separator that is interposed between the first electrode plate and the second electrode plate, wherein the electrode tab is incorporated into the electrode current collector in an area of either the first or the second electrode plate where the corresponding electrode active material layer is not coated. Since an electrode tab is formed by cutting a portion of an electrode current collector and folding upward, deformation of a jelly-roll type battery unit is prevented.