Pre-Curved Battery Electrode Structure for Warpage Suppression
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Solution Overview
Problem
The production of electrodes for secondary batteries faces challenges due to residual stress and warpage caused by differences in extension between applied and unapplied regions of the current collector, leading to misalignment issues during electrode group assembly.
Innovation Solution
The electrode is designed with an active material-containing layer having a first edge with an arc shape and a second edge opposite to it, supported by a current collector with an active material-supporting section and an active material-non-supporting section. This configuration allows the electrode to be curved in a direction opposite to the conventional curve generated by pressing, thereby reducing strain and warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the electrode is compressed more densely to fill active material into limited space, then the capacity increases, but the residual stress and warpage increase due to difference in extension between applied and unapplied regions
Solution Approach 1:
The patent applies preliminary action by pre-curving the current collector in the opposite direction to the expected warpage before the coating and compression processes. This pre-curving compensates for the residual stress that will develop during densification, allowing the electrode to maintain flatness after compression while still achieving high active material filling density
Solution Approach 2:
The patent implements preliminary anti-action by curving the current collector in the opposite direction to the anticipated warpage caused by differential extension. This counter-curving creates a pre-stress that opposes the residual stress generated during compression, thereby preventing net warpage while enabling dense packing of active material
2Productivity
If tension is applied to extend the electrode to reduce curving, then the production yield improves, but the process complexity and time increase
Solution Approach 1:
The patent eliminates the need for post-compression tensioning by performing the curving adjustment beforehand. The current collector is pre-curved in the opposite direction before coating and compression, so that when the electrode is assembled, the pre-curving compensates for warpage without requiring additional tensioning steps, thereby simplifying the production process while maintaining high yield
Solution Approach 2:
The patent extracts the warpage correction step from the post-compression process and integrates it into the pre-compression preparation stage. By curving the current collector beforehand, the method removes the need for separate tensioning operations to correct warpage, reducing process complexity while achieving the same productivity improvement
3Strength
If the current collector is compressed uniformly, then the structural integrity is maintained, but the unapplied region does not extend, causing misalignment in electrode group assembly
Solution Approach 1:
The patent applies asymmetry by curving the current collector in the opposite direction to the expected warpage before compression. This asymmetric pre-curving compensates for the differential extension that occurs during compression of the applied region versus the unapplied region, ensuring that both regions extend appropriately and align correctly in the final electrode group assembly while maintaining structural integrity
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 modified electrode design effectively suppresses the increase in curving amount over time, leading to improved yield and reduced production inefficiencies in electrode group assembly by minimizing misalignment issues.
Implementation Method 1
The applied region of the current collector that has been compressed extends due to plastic deformation; however, the unapplied region of the current collector, which is not coated with the electrode materials, does not extend because the pressure of press is not applied to the exposed portion of the current collector
Data Source
AI summary
According to one embodiment, an electrode is provided. The electrode includes an active material-containing layer and a current collector. The active material-containing layer comprises a first edge having an arc shape and a second edge positioned opposite to the first edge. The current collector comprises an active material-supporting section supporting the active material-containing layer, and an active material-non-supporting section. The curving amount is represented by a maximum distance from the first edge to a reference line connecting two points on the first edge. The curving amount is in a range of −1 mm or more and less than 0 mm.