Button Cell Electrode Separator Coil With Local Reinforcement

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Solution Overview

Problem

In button cells with wrap composite bodies, the direct contact between separator bands and contact strips can lead to short circuits due to the risk of damage to thin separator bands, and the use of Kapton tapes to mitigate this risk can negatively impact cell performance.

Innovation Solution

The procedure involves reinforcing at least one separator in the risk areas by increasing its thickness, either through the application of fixation foils or by folding the separators, to prevent direct contact with sharp contact strips and reduce the risk of short circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If separator bands are made thin to reduce cell size, then cell compactness is improved, but the risk of short circuits increases due to damage from sharp contact strips

Engineering Contradiction:
Improvecell sizeVSAvoidshort circuit risk
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The patent applies local reinforcement to the separator bands at specific locations where contact strips are positioned. The separator bands have increased thickness (e.g., 15-20 μm) at these critical zones while maintaining thin thickness (e.g., 3-5 μm) in other areas. This local quality change protects against short circuits at contact points without compromising cell compactness overall.

Inventive Principle:
Principle #3Local quality

2Reliability

If Kapton tapes are applied to protect separator bands, then short circuit risk is reduced, but cell performance is negatively impacted

Engineering Contradiction:
Improveshort circuit protectionVSAvoidcell performance
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent removes the Kapton tape layer from the cell structure and replaces it with inherently thicker separator bands at critical locations. This extraction eliminates the harmful adhesive substances associated with Kapton tapes while maintaining the protective function against short circuits through the increased separator thickness at contact strip locations.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If separator thickness is increased to prevent short circuits, then reliability is improved, but cell compactness deteriorates

Engineering Contradiction:
Improveshort circuit preventionVSAvoidcell volume
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The separator bands exhibit spatially varying thickness with localized reinforcement at contact strip positions and thin sections elsewhere. This local quality approach provides short circuit prevention exactly where needed (at contact points) while minimizing the overall volume increase, as only specific zones have increased thickness rather than the entire separator structure.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3605697B1Method for producing an electrode separator coil, electrode separator coil and button cell comprising such a coil
Publication Date: 2025.04.23 VARTA MICROBATTERY GMBH
  • EP3605697B1 patent drawingFigure 1~2
  • EP3605697B1 patent drawingFigure 3~4
  • EP3605697B1 patent drawingFigure 5

AI summary

A method for producing an electrode-separator winding (100) with the sequence first current collector (101) / separator (103) / second current collector (102) / separator (104) or second current collector (102) / separator (103) / first current collector (101) / separator (104) is described, in which a contact strip (107, 108) is welded to at least one contact section (101b and 102b) for electrical contacting of the current collectors (101 and 102) or at least one of the contact sections (101b and 102b) is folded over to form a contact strip (107, 108), wherein at least one of the separators (103 and 104) is located in at least one risk area (103a, 104a) in which the at least one separator (103 and 104) within the completed electrode separator winding at the at least one contact section (101b and 102b) in which the contact strip (107, 108) is welded,or is reinforced at least on which at least one contact section (101b and 102b) is folded to form a contact strip (107, 108). Furthermore, an electrode separator winding (100) produced according to the method and a button cell with this winding are described.