Separator Web Tension Control for Z-Folding Battery Stacks
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Solution Overview
Problem
Current methods for Z-folding battery cell manufacturing face challenges in maintaining consistent web tension during the feeding of separator webs, leading to issues such as web misalignment, creasing, and mechanical stress, which affect the quality and cycle time of the battery cells.
Innovation Solution
A separator web feed device with a web tension transmission unit that divides the web run into sections with different tensions, controlled by a position-controlled web tension control unit, using a drive unit with driven and deflection rollers to maintain homogeneous tension and compensate for fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the separator web is fed with high tension to maintain alignment during Z-folding, then web misalignment is reduced, but web tension peaks increase causing mechanical stress and potential damage
Solution Approach 1:
The web run is divided into multiple sections (first web run section and second web run section) with different tension characteristics. The first section maintains higher tension for alignment during separator web feeding, while the second section uses lower tension to reduce mechanical stress on the stacked battery cells. This segmentation allows each section to be optimized for its specific function.
Solution Approach 2:
Different tension levels are applied to different sections of the separator web based on local requirements. The first web run section (before the separator guide unit) uses higher tension to prevent misalignment during the reciprocating motion, while the second web run section (after the separator guide unit) uses lower tension to protect the stacked cells from damage.
2Productivity
If the separator guide unit reciprocates quickly to reduce cycle time, then productivity increases, but web tension fluctuations increase causing misalignment and quality issues
Solution Approach 1:
The web tension control is segmented into two distinct sections: the first section provides stable tension during the reciprocating motion to maintain alignment, while the second section allows for tension relaxation. This enables the separator guide unit to reciprocate quickly for reduced cycle time while maintaining web alignment through the controlled tension distribution.
Solution Approach 2:
The first web run section with its higher tension is positioned beforehand to stabilize the separator web before it enters the reciprocating separator guide unit. This preliminary tensioning prevents misalignment from occurring during the high-speed reciprocation, allowing for faster cycle times without sacrificing alignment quality.
3Stability of the object's composition
If uniform tension is applied throughout the entire web run, then web stability is maintained, but the ability to compensate for position-dependent tension fluctuations is reduced
Solution Approach 1:
Instead of applying uniform tension throughout the entire web run, the system segments the web run into two sections with different tension characteristics. The first section provides stable tension for overall web stability, while the second section is specifically designed to compensate for position-dependent tension fluctuations that occur during the reciprocating motion of the separator guide unit.
Solution Approach 2:
The tension control system applies different tension qualities to different sections based on local requirements. The first web run section uses stable, consistent tension to maintain overall web stability, while the second section uses variable tension to specifically address and compensate for fluctuations that occur at different positions during reciprocation.
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 reduces web tension peaks, minimizes misalignment, and significantly shortens cycle times, resulting in higher-quality battery stacks with reduced mechanical stress and improved production efficiency.
Implementation Method 1
a web tension transmission unit (20) dividing a web run of the separator web (16) in the separator web supply device (18) into sections (38, 40) with different web tensions
Data Source
AI summary
Feeding a separator to a Z-folding process at the manufacture of battery cells, in which the separator is fed by: feeding a separator web with a first web tension to a web tension transmission unit which divides the web run of the separator web into sections with different web tensions; guiding the separator web from the web tension transmission unit with a second web tension to a separator guide unit; supplying the separator web in a Z-shape with a reciprocating movement of the separator guide unit in order to stack the battery cell; and controlling the second web tension depending on the position of the separator guide unit. In addition, apparatus, devices, controls, and computer programs for performing the feeding.