Vacuum-Clamped Separator Tensioning for Wrinkle-Free Electrode Stacking
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Solution Overview
Problem
Battery electrodes require precise alignment and tensioning to ensure efficient ion transfer during charging and discharging, but existing methods struggle with maintaining wrinkle-free and aligned separator sheets, leading to issues like uneven current density and internal shorts.
Innovation Solution
Applying in-plane tension to separator sheets using vacuum clamps along their edges, allowing for inspection and maintaining tension while stacking electrodes, ensures proper alignment and defect identification, thereby preventing wrinkles and other defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If separator sheets are made thin to reduce cell volume, then volume efficiency is improved, but alignment precision and wrinkle-free condition deteriorate
Solution Approach 1:
The patent applies preliminary tensioning to the separator sheet before electrode assembly is formed. Vacuum clamps are used to stretch and tension the separator sheet in advance, ensuring it remains wrinkle-free and properly aligned during subsequent stacking operations. This preliminary action prevents alignment issues that would otherwise occur with thin separator sheets.
Solution Approach 2:
The patent changes the physical state and mechanical properties of the separator sheet by applying vacuum tension. The vacuum clamps create negative pressure that stretches the separator material, altering its dimensional stability and rigidity temporarily during assembly. This parameter change allows thin separators to maintain precision without increasing thickness.
2Manufacturing precision
If separator sheets are tensioned to maintain alignment, then alignment precision is improved, but device complexity increases due to additional tensioning mechanisms
Solution Approach 1:
The vacuum clamps serve multiple functions: they tension the separator sheet for alignment, holds electrodes in position during stacking, and can be used for inspection. This multi-functionality reduces the need for separate tensioning devices, simplifying the overall system despite the added precision capability.
Solution Approach 2:
The vacuum clamps automatically maintain tension on the separator sheet throughout the assembly process. Once vacuum is applied, the clamps self-regulate the tension force without requiring additional control mechanisms. The system uses the vacuum pressure itself to maintain consistent alignment, reducing the need for complex active control systems.
3Manufacturing precision
If vacuum clamps are used to apply tension to separator sheets, then alignment precision is improved, but manufacturing time increases due to additional inspection steps
Solution Approach 1:
The vacuum tensioning is applied continuously throughout the entire assembly process rather than being applied and then removed. This continuous tension maintains alignment precision during electrode placement, inspection, and stacking operations. The useful action of tensioning continues without interruption, eliminating the need to re-tension the separator after initial application.
Solution Approach 2:
The patent combines the tensioning function with the inspection function. By maintaining vacuum tension throughout the assembly process, the system ensures that any defects or misalignments are immediately visible during inspection without the separator relaxing or developing wrinkles. This merging of functions eliminates separate tensioning and inspection steps.
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 method ensures precise alignment and tensioning of electrodes and separators, reducing defects and improving battery performance by maintaining uniform current densities and preventing internal shorts.
Implementation Method 1
reducing pressure within vacuum ports of the vacuum clamps thereby forcing the separator sheet against the vacuum clamps
Data Source
AI summary
Described herein are methods and systems for forming electrode stacks. For example, a method may comprise applying in-plane tension to a separator sheet and inspecting the separator sheet while applying the in-plane tension. This under-tension allows identifying any defects on the separator sheets that are not curable by tension, e.g., permanent wrinkles, tears, contaminants, and the like. Furthermore, this in-plane tension can be used for stacking and maintained while an electrode is placed over the separator. The tension can be formed by positioning vacuum clamps along the opposite edges (e.g., long edges) of the separator sheet. For example, one vacuum clamp can extend along the entire separator edge. Alternatively, multiple clamps can be distributed along the edge. Furthermore, additional clamps can be positioned along the remaining two edges (of the rectangular separator sheet). The vacuum clamps can move in various directions and/or rotate to apply the in-plane tension.