Pouch Battery Cell Dual Sealing for Thermal Propagation Resistance
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Solution Overview
Problem
Pouch type battery cells face safety issues due to rapid thermal propagation, which can lead to fires and explosions, primarily because existing sealing portions lack sufficient thermal resistance and sealing strength.
Innovation Solution
A pouch type battery cell design featuring a metal sealing portion with stainless-steel layers welded together using a laser, providing a dual seal outside an insulation sealing portion formed by thermally fusing resin layers, to enhance thermal resistance and sealing strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional sealing portion is used in pouch type battery cells, then the device complexity is reduced and ease of manufacture is improved, but the thermal resistance and sealing strength are insufficient leading to safety issues
Solution Approach 1:
The sealing portion is divided into multiple functional layers: an inner sealing layer for basic sealing, an intermediate insulation layer for thermal resistance, and an outer sealing layer for enhanced sealing strength. This segmentation allows each layer to perform its specific function optimally, resolving the contradiction between safety requirements and structural complexity by making the complexity functional and necessary.
Solution Approach 2:
The sealing portion uses composite material structure combining different materials with complementary properties: resin materials for insulation and flexibility, metal materials for strength and thermal resistance, and adhesive materials for bonding. This composite approach enables the sealing portion to simultaneously achieve high thermal resistance, strong sealing, and structural integrity without excessive complexity.
2Strength
If the sealing strength is increased to prevent thermal propagation, then the thermal resistance is improved, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
The sealing layers are pre-assembled in a predetermined sequence during the battery assembly process, with alignment marks and guide structures ensuring proper positioning before final sealing. This preliminary arrangement eliminates the need for complex real-time alignment during sealing operations, maintaining high sealing strength while preserving manufacturing efficiency.
Solution Approach 2:
The sealing process replaces complex mechanical fastening systems with thermal bonding and adhesive bonding processes. The sealing portions are bonded using heat and pressure in a controlled manner, eliminating the need for multiple mechanical fasteners, rivets, or clips, thereby reducing manufacturing steps while achieving strong sealing.
3Temperature
If a multi-layer sealing structure is implemented to enhance thermal resistance, then the sealing strength is improved, but the device complexity increases
Solution Approach 1:
The multi-layer structure is applied specifically to the sealing portion where thermal resistance is critical, rather than throughout the entire battery case. The insulation layer is concentrated at the sealing interface where thermal propagation risk is highest, providing targeted thermal protection without adding unnecessary complexity to other parts of the battery structure.
Solution Approach 2:
The sealing portion is designed to perform multiple functions simultaneously: mechanical sealing to contain electrolyte, thermal insulation to resist heat transfer, structural reinforcement to maintain case integrity, and electrical insulation to prevent short circuits. This multi-functionality justifies the multi-layer structure by consolidating multiple protective functions into a single integrated component rather than adding separate systems for each function.
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
The dual metal sealing portion significantly increases the sealing strength and maintains stability at high temperatures, effectively preventing or delaying thermal propagation to other battery cells, thus enhancing safety.
Implementation Method 1
metal sealing portion with stainless-steel layers welded together using a laser
Implementation Method 2
insulation sealing portion formed by thermally fusing resin layers
Data Source
AI summary
A pouch type battery cell according to an embodiment of the present invention may include an electrode assembly accommodated between a pair of cases, each of which include a first resin layer constituting an innermost layer, a second resin layer constituting an outermost layer, and a metal layer stacked between the first and second resin layers. The pouch type battery cell may include a cup portion, accommodating the electrode assembly, an insulation sealing portion, in which the first resin layers of the pair of cases are sealed to each other, a folded portion, in which an edge of one case of the pair of cases is folded to surround an edge of the other case, and a metal sealing portion, provided on the folded portion, in which the metal layers of the pair of cases are sealed to each other.