Pouch Battery Sealing Shape Control via Bidirectional Pressure
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Solution Overview
Problem
The existing sealing process for pouch-type secondary batteries results in a temporary attachment region with a ball shape, which is vulnerable to insulation and high-temperature durability, lacking a separate system for controlling its shape.
Innovation Solution
A method involving the application of external forces in perpendicular directions to the sealing portion, combined with heat and pneumatic pressure, to control the shape of the temporary attachment region and ensure uniform heat transfer, using a multi-layer structure with aluminum, polyethylene terephthalate resin, and polypropylene adhesive layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sealing process is used, then sealing operation is simple, but the temporary attachment region forms a ball shape that is vulnerable to insulation and high-temperature durability
Solution Approach 1:
The sealing process is divided into multiple sequential steps: first applying pressure in the longitudinal direction to bond the pouches, then applying external force in the thickness direction to control the temporary attachment region shape. This segmentation allows each step to address specific requirements without overwhelming complexity.
Solution Approach 2:
External force is applied in advance during the sealing process to prevent the formation of the harmful ball shape in the temporary attachment region. By controlling the shape proactively during sealing rather than correcting it afterward, the insulation durability is improved while maintaining process efficiency.
2Manufacturing precision
If pressure is applied only in longitudinal direction, then sealing structure is simple, but heat transfer is uneven and temporary attachment region deforms
Solution Approach 1:
The sealing process transitions from unidirectional pressure application (longitudinal direction only) to bidirectional pressure application by adding external force in the thickness direction. This dimensional addition enables precise control of the temporary attachment region shape while ensuring uniform heat transfer across the sealing surface.
Solution Approach 2:
The sealing process controls multiple parameters including pressure magnitude, application timing, and duration. By optimizing these parameters, the temporary attachment region maintains the desired flat shape without excessive deformation, achieving manufacturing precision without requiring overly complex equipment.
3Strength
If adhesive layer is heated during sealing, then bonding strength increases, but the temporary attachment region may form ball shape reducing insulation properties
Solution Approach 1:
External force is applied preliminarily during the heating process to counteract the tendency of the adhesive layer to form a ball shape. This preventive measure ensures that even as the adhesive softens and bonds the pouches together, the temporary attachment region maintains a flat geometry that preserves insulation properties.
Solution Approach 2:
The sealing process applies different conditions to different regions: the adhesive layer receives heat and pressure for strong bonding, while the temporary attachment region receives additional external force to maintain its flat shape and insulation quality. This localized differentiation ensures both strength and insulation durability.
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 improves the insulation and high-temperature durability of the sealing region, preventing ignition, explosion, and fire accidents by stabilizing the insulation properties and maintaining adequate sealing strength.
Implementation Method 1
the adhesive layer present at the sealing portion melts and flows due to the heat generated during sealing
Implementation Method 2
the adhesive layer present at the sealing portion melts and flows due to the heat generated during sealing
Implementation Method 3
a first pressure is applied to an outer circumferential sealing portion, where the upper pouch and the lower pouch are sealed
Data Source
AI summary
The present disclosure relates to a method for sealing a pouch casing of a pouch-type secondary battery, which includes the steps of: a receiving step in which an electrode assembly is received in an inner space formed between an upper pouch and a lower pouch; and a sealing step in which a first pressure is applied to an outer circumferential sealing portion, where the upper pouch and the lower pouch are sealed, in the longitudinal direction, and then the pressure is relieved, wherein the sealing step is carried out by applying external force to the upper pouch in the upward direction and to the lower pouch in the downward direction, or by applying a second pressure working in perpendicular to the first pressure to the sealing portion from the inner part of the pouch casing in a direction toward the outside.