Jelly Roll Tape Overlap Layout for Pouch Cell Flatness
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Solution Overview
Problem
The surface unevenness of jelly rolls in lithium-ion batteries leads to poor flatness and interface adhesion, resulting in reduced cycle life and increased expansion and deformation.
Innovation Solution
A jelly roll design where the inner surface of the negative electrode plate's bending region is covered by a first tape layer, with projections of the tape layer connected or partially overlapped with the winding head, ensuring uniform thickness distribution and reducing surface unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional jelly roll structure is used, then the manufacturing process is simple, but the surface unevenness is serious and flatness is poor
Solution Approach 1:
The patent applies local quality by adding a first tape layer specifically to the bending region of the negative electrode plate where surface unevenness occurs. This localized modification compensates for thickness differences in the jelly roll without requiring changes to the entire structure, thereby improving flatness while maintaining overall structural simplicity.
Solution Approach 2:
The patent introduces asymmetry by applying the first tape layer only to one side (the bending region) of the negative electrode plate rather than uniformly across the entire structure. This asymmetric approach addresses the specific location of surface unevenness, improving flatness without adding symmetric complexity throughout the whole device.
2Reliability
If the jelly roll has serious surface unevenness, then the manufacturing process is simple, but the interface adhesion is poor and cycle life is reduced
Solution Approach 1:
The patent applies preliminary action by pre-installing the first tape layer on the bending region of the negative electrode plate before assembly. This advance preparation ensures that the tape is in position to provide adhesion support during battery formation and cycling, improving reliability without complicating the overall manufacturing process.
Solution Approach 2:
The first tape layer acts as an intermediary element between the negative electrode plate and the surrounding structure. It mediates the interface adhesion by providing a bonding surface that enhances attachment in the bending region, thereby improving cycle life and reliability while maintaining ease of manufacture through a straightforward additive approach.
3Manufacturing precision
If the first tape layer is added to cover the bending region, then the flatness and interface adhesion are improved, but the device complexity increases
Solution Approach 1:
The first tape layer is applied locally only to the bending region of the negative electrode plate where flatness issues occur, rather than covering the entire jelly roll structure. This localized application improves flatness while minimizing the increase in device complexity by limiting the additional component to only where it is needed.
Solution Approach 2:
The patent applies partial action by using a first tape layer that covers only the critical bending region rather than the entire negative electrode plate or jelly roll. This partial coverage is sufficient to improve flatness and interface adhesion in the problem area without unnecessarily increasing device complexity through full-coverage application.
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
Improves the flatness and interface adhesion of the battery cell, enhancing its cycle life and preventing expansion and deformation.
Implementation Method 1
the first tape layer includes a substrate layer and an adhesive layer, and the first tape layer adheres to a surface of the bending region through the adhesive layer
Data Source
Figure 1
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AI summary
The present application provides a jelly roll and a punch cell, and relates to the field of lithium battery technologies. The jelly roll includes a negative electrode plate, along a winding direction, an inner surface of a bending region of the negative electrode plate is covered by a first tape layer, and in a thickness direction of the jelly roll, a projection of two ends of the first tape layer is connected to or partially overlapped with a projection of a winding head of the negative electrode plate. As a result, surface unevenness of the jelly roll is improved, thereby improving a flatness of a battery cell.