Pouch Cell Secondary Sealing for Controlled Venting
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Solution Overview
Problem
Existing methods for manufacturing pouch-shaped battery cells do not effectively adjust sealing strength to prevent swelling and explosion by controlling venting, leading to potential ignition and explosion risks due to internal pressure increases.
Innovation Solution
A manufacturing method involving primary and secondary sealing processes with specific temperature and pressure conditions to adjust sealing strength, reducing the size of the poly ball and controlling venting direction and time, using a laminate sheet with distinct layers for the battery case.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sealing force of the battery case is increased to prevent swelling, then the battery case becomes more secure, but gas cannot be discharged and the battery may explode when internal pressure increases
Solution Approach 1:
The patent applies different sealing strengths to different regions of the battery case. The sealing portion is divided into a first region with higher sealing strength and a second region with lower sealing strength. This local differentiation allows the case to maintain overall sealing integrity while providing a controlled weak point for safe gas discharge, resolving the contradiction between preventing swelling and allowing venting.
Solution Approach 2:
The sealing portion is segmented into multiple regions with different sealing characteristics. By dividing the sealing portion into a first sealing region and a second sealing region, the patent creates distinct functional zones that can independently respond to internal pressure, enabling both secure sealing and controlled venting simultaneously.
2Strength
If the poly ball size is increased to enhance sealing force, then sealing strength improves, but venting cannot occur even at high internal pressure
Solution Approach 1:
The patent creates local quality variation in the poly ball structure by forming different regions with different sealing forces. The first poly ball region corresponds to the first sealing region with higher sealing force, while the second poly ball region corresponds to the second sealing region with lower sealing force. This allows the system to maintain strong sealing where needed while providing controlled venting pathways.
3Ease of manufacture
If uniform sealing is applied across the entire battery case, then manufacturing is simplified, but controlled venting cannot be achieved
Solution Approach 1:
The patent implements local quality differentiation in the sealing process by applying different sealing conditions to different regions. The first sealing region receives different sealing parameters (temperature, pressure, time) compared to the second sealing region, creating distinct sealing strengths without requiring completely different manufacturing processes.
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 method effectively reduces the sealing force in targeted areas, allowing controlled venting before explosion, enhancing safety by preventing ignition in high-temperature environments.
Implementation Method 1
the outer edge of the battery case is sealed by thermal fusion. When the laminate sheet is heated and pressed, the adhesive layer is melted, whereby a sealed portion of an upper case and a sealed portion of a lower case are coupled to each other
Implementation Method 2
the primary sealing and the secondary sealing are performed by pressing an upper case and a lower case using a high-temperature sealing tool
Data Source
AI summary
The prevent invention relates to a pouch-shaped battery cell manufacturing method including receiving an electrode assembly in a battery case made of a laminate sheet, primarily sealing an outer edge of the battery case, and secondarily sealing at least a part of the primarily sealed outer edge, wherein sealing force of a sealed portion formed after both the primary sealing and the secondary sealing are performed is low, whereby it is possible to induce the venting position and venting time of a pouch-shaped battery cell.