Pouch Cell Seal With Fault-Activated Heating Element
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Solution Overview
Problem
Pouch cells in Li-ion batteries face safety risks due to uncontrolled gas generation and potential explosion, as they lack a mechanism for controlled release of excess gas, which is exacerbated by their soft laminate packaging and high reactivity.
Innovation Solution
A fault-activated heating element is integrated within or on top of the seal area of the pouch cell, activated by a pressure switch to delaminate the packaging seal when internal pressure exceeds a predetermined threshold, allowing for controlled venting of excess gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If pouch cells use soft laminate packaging to achieve lightweight and high energy density, then weight reduction and energy density improvement are achieved, but the cells become vulnerable to uncontrolled gas generation and potential explosion
Solution Approach 1:
The seal is segmented into multiple layers (first seal layer, second seal layer, and intermediate layer) with different properties. The intermediate layer acts as a delamination layer that can separate under excessive pressure, creating a controlled venting path while maintaining the overall integrity of the pouch cell structure.
Solution Approach 2:
The intermediate layer serves as an intermediary component between the first and second seal layers. This layer is specifically designed to delaminate under excessive internal pressure, acting as a mediator that enables controlled gas release while preventing catastrophic failure of the entire seal structure.
2Strength
If strong sealing is used to prevent air exposure and maintain cell integrity, then seal strength and protection are improved, but gas venting becomes uncontrolled and potentially explosive
Solution Approach 1:
Different regions of the seal have different properties: the first and second seal layers provide strong sealing to prevent air exposure, while the intermediate layer between them is designed with delamination capability for controlled venting. This local differentiation allows simultaneous achievement of strong sealing and safe gas release.
Solution Approach 2:
The seal structure is pre-designed with an inherent weak point (the intermediate layer) that will delaminate under excessive pressure. This preliminary design prevents the harmful effect of uncontrolled explosion by providing a predetermined failure path for gas release before catastrophic failure can occur.
3Reliability
If the seal is made exceptionally strong to prevent air exposure, then cell protection is improved, but the cell may fail explosively when the pouch finally bursts
Solution Approach 1:
The intermediate layer acts as a cushioning mechanism that activates before catastrophic failure. When excessive pressure builds up, this layer delaminates first, providing a controlled venting path that relieves pressure gradually, cushioning against the harmful effect of explosive failure.
4Reliability
If rupture disks are incorporated in hard case cells for controlled venting, then gas release control is achieved, but pouch cells lack this mechanism and remain vulnerable to ballooning and explosive venting
Solution Approach 1:
The intermediate layer in the seal serves multiple functions: it maintains seal integrity during normal operation, provides a controlled delamination path for gas venting under excessive pressure, and prevents catastrophic failure. This multi-functional design eliminates the need for separate rupture disk components in pouch cells.
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 provides a safe and reliable mechanism for pouch cells to vent excess pressure without risking explosion, maintaining seal integrity and being compatible with existing manufacturing methods, while also allowing for potential resealing of the cell.
Implementation Method 1
A fault-activated heating element is integrated within or on top of the seal area of the pouch cell, activated by a pressure switch to delaminate the packaging seal when internal pressure exceeds a predetermined threshold
Data Source
AI summary
The present invention relates to the field of battery cells, particularly to a pouch cell comprising a packaging seal, a heating element and a fault switch, wherein the fault switch will activate the heating element to generate heat to make the packaging seal delaminate when the inner space of the pouch cell reaches a predetermined pressure, such that the pouch cell vents. The mechanism and components of these venting concepts can be designed to be fully compatible with existing manufacturing methods and typical cell handling situations. The most favorable configuration has both vent device components outside the cell, with nothing passing through or even into the seal. Such a configuration has the advantage of having no impact on the seal integrity relative to a conventional pouch cell, is easy to manufacture, and has improved safety.