Pouch Battery Sealing Tool Geometry for Poly-Ball Reduction
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Solution Overview
Problem
Existing secondary battery sealing tools result in reduced sealing force due to a flat sealing surface, leading to easy bending of the battery case and contamination of the electrode assembly by a large poly-ball formed when pressure increases, along with insulation defects from a thin sealant layer.
Innovation Solution
The use of a sealing tool with a recessed weak sealing part for the inner portion and a pattern part with regularly repeating ribs and grooves for the outer portion, which reduces the size of the poly-ball and increases the sealing force by enhancing the surface area and bending path length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a flat sealing surface is used in the sealing tool, then the sealing process is simple, but the sealing force is reduced and the side is easily bent
Solution Approach 1:
The sealing part is designed with a curved surface instead of a flat surface. The curvature radius is specifically controlled to be 0.5mm to 2mm, which allows the sealing part to apply pressure more effectively on the side, increasing the sealing force while preventing the side from being easily bent.
2Strength
If pressure is increased to improve sealing force, then sealing effectiveness improves, but a large poly-ball is formed and contaminates the electrode assembly
Solution Approach 1:
The curved surface of the sealing part distributes the pressure more evenly across the sealing area, preventing excessive localized pressure that would cause the sealant layer to melt and form large poly-balls. This reduces contamination of the electrode assembly while maintaining adequate sealing force.
Solution Approach 2:
The curvature radius of the sealing part is optimized to a specific range (0.5mm to 2mm), which changes the pressure distribution parameters during sealing. This parameter optimization prevents excessive melting of the sealant layer, reducing poly-ball formation while ensuring sufficient sealing force.
3Strength
If pressure is increased to improve sealing force, then sealing effectiveness improves, but the sealant layer thickness is reduced causing insulation defects
Solution Approach 1:
The curved sealing surface distributes pressure more uniformly, preventing excessive compression that would thin the sealant layer to the point of compromising insulation. This maintains adequate sealant layer thickness for insulation while achieving necessary sealing force.
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 configuration effectively reduces the size of the poly-ball, prevents contamination of the electrode assembly, and maintains adequate insulation by increasing the sealing force and surface area, thereby enhancing the overall sealing performance.
Implementation Method 1
If the pressure that presses the side increases by the sealing tool, a portion of the sealant layer is melted, and thus, a poly-ball protruding toward an accommodation space of a cup part is largely formed.
Data Source
AI summary
An apparatus for sealing a battery case includes: a sealing tool configured to seal a side of a pouch-type secondary battery, wherein the sealing tool includes: a body; and a sealing part formed at one side of the body and configured to directly press the side so as to seal the side, wherein the sealing part includes: a weak sealing part configured to seal an inner portion of the side and formed to be recessed inward; and a pattern part configured to seal an outer portion of the side and formed by regularly repeating a rib formed to protrude outward and a groove formed to be recessed inward.