Pouch Battery Sealing Structure With Vent Layer and Corner Cutout
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Solution Overview
Problem
Existing pouch-type rechargeable batteries lack an effective venting mechanism to efficiently discharge internal gases under elevated temperature and pressure conditions, potentially leading to ignition or explosion.
Innovation Solution
The rechargeable battery incorporates a vent layer within a sealing portion of the case, which includes a cutout portion to facilitate rapid gas discharge. The vent layer is designed to have a lower melting point than the polymer layers of the case, allowing it to open and relieve internal pressure when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a pouch-type battery structure is used to facilitate miniaturization and slimming, then the battery size and thickness are reduced, but the battery lacks an effective venting mechanism to discharge internal gases under elevated temperature and pressure conditions
Solution Approach 1:
The sealing portion is divided into multiple functional regions: a first sealing portion for sealing, a second sealing portion extending from it, and a cutout portion at the corner. The vent layer is selectively disposed on the bonding surface of the second sealing portion, creating segmented functional zones that enable both compact sealing and effective venting through different structural elements.
Solution Approach 2:
The vent layer is placed only on the bonding surface of the second sealing portion rather than uniformly across the entire sealing structure. This localized placement creates a specific region with different properties (lower melting point) compared to the rest of the sealing portion, enabling targeted gas discharge functionality while maintaining overall structural integrity and compactness.
2Reliability
If a vent layer with lower melting point is introduced to enable gas discharge, then the venting function is improved, but the bonding strength between the vent layer and sheets must be controlled to ensure proper activation
Solution Approach 1:
The vent layer is designed with specific parameter changes: a lower melting point (105-115°C for the coating layer) compared to the polymer sheets, and controlled bonding strength (0.5-1.4 kgf) through material composition (cast polypropylene with mixed resin or metal). These parameter adjustments enable the vent layer to detach at appropriate temperature and pressure conditions, balancing venting functionality with bonding requirements.
3Volume of moving object
If the sealing portion is bent to face the side surface to reduce battery size, then the compactness is improved, but the gas discharge path must be optimized through cutout portions to ensure rapid venting
Solution Approach 1:
The cutout portion is pre-formed at the corner of the second sealing portion before battery operation. This preliminary structural preparation creates a predetermined gas discharge path that becomes active when the vent layer detaches, enabling rapid gas discharge without requiring additional structural changes during emergency conditions.
Solution Approach 2:
The sealing portion is bent from a flat configuration to a three-dimensional structure where the second sealing portion extends outward and the cutout portion is positioned at the corner. This dimensional change creates a spatial configuration that facilitates gas discharge while maintaining compact battery overall dimensions.
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 design enables rapid and efficient discharge of internal gases, effectively reducing the risk of ignition or explosion by quickly relieving internal pressure, while also allowing for a reduction in overall battery size through the bending of sealing portions.
Implementation Method 1
a melting point of the vent layer may be less than a melting point of the polymer layer
Implementation Method 2
A bonding strength of the vent layer to at least one of the first sheet and/or the second sheet may be less than a bonding strength between the first sheet and the second sheet
Data Source
AI summary
A rechargeable battery includes: an electrode assembly; a case comprising a first sheet disposed at an upper side of the electrode assembly in a thickness direction and a second sheet disposed at a lower side of the electrode assembly along the thickness direction, an accommodating portion at least partially surrounding the electrode assembly and formed by the first and second sheets, a sealing portion, formed by the first and second sheets connected to an edge of the accommodating portion and bent to face a side surface of the accommodating portion, the sealing portion comprising a vent layer provided in the sealing portion, and a cutout portion disposed at one end portion of the sealing portion, wherein the vent layer is disposed on a bonding surface between the first sheet and the second sheet and contacts a corner of the accommodating portion and the cutout portion.