Pouch Battery Sealing Vent Structure for Rapid Gas Discharge
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Solution Overview
Problem
Rechargeable batteries, particularly pouch-type batteries, face challenges in safely managing internal pressure and temperature rises due to factors like fast charging, internal short circuits, and external impacts.
Innovation Solution
The design incorporates a vent function with a cutout portion and a vent layer at the sealing portion of the battery case, allowing for efficient discharge of internal gas under specific temperature and pressure conditions, thereby preventing ignition and explosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the sealing portion is bent to face the side surface of the accommodating portion, then the overall size of the battery is reduced, but the venting efficiency may be compromised
Solution Approach 1:
The sealing portion is divided into a first portion facing the side surface and a second portion extending outward, creating segmented functional zones that enable both compact positioning and effective venting
Solution Approach 2:
The cutout portion acts as an intermediary element that facilitates gas discharge from the accommodating portion through the vent layer, bridging the compact sealed structure with the venting function
2Reliability
If a vent layer with lower melting point is used, then gas discharge is facilitated under high temperature conditions, but the bonding strength may be reduced
Solution Approach 1:
The vent layer is designed with a melting point (105°C to 115°C) lower than the polymer layer, creating a parameter difference that enables temperature-triggered venting while maintaining adequate bonding strength (0.5 kgf to 1.4 kgf) under normal conditions
Solution Approach 2:
The vent layer utilizes phase transition (melting) at a specific temperature range to activate the gas discharge function, transforming from a bonded state to a venting state under thermal stress
3Productivity
If the cutout portion is positioned to contact the corner of the accommodating portion, then the gas discharge path is shortened and venting is accelerated, but the structural complexity increases
Solution Approach 1:
The cutout portion is pre-positioned at the corner of the second portion to establish an optimal gas discharge path before any thermal or pressure events occur, enabling immediate and accelerated venting when needed
Solution Approach 2:
The first portion and second portion of the sealing portion are merged into a single bent structure, integrating the facing surface and the outward extension with the cutout portion to create a compact yet functional design
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 solution effectively reduces the overall size of the battery while enhancing safety by facilitating rapid gas discharge and pressure relief, thus preventing dangerous conditions within the battery.
Implementation Method 1
Each of the first sheet and the second sheet may include a polymer layer, and 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
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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.