Two-Stage Cell Vent with Metal and Plastic Layers
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Solution Overview
Problem
Lithium-ion electrochemical energy stores face issues with gas bubble formation and vent blockage during thermal anomalies, leading to safety concerns and potential deformation or discharge, as well as water diffusion problems.
Innovation Solution
A two-stage temperature-sensitive cell vent is designed with a metal first layer and a plastic second layer, arranged in series, where the plastic layer yields earlier to allow pressure reduction and prevent blockage, and a third plastic barrier at the breaking point prevents water diffusion, ensuring controlled pressure release and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer cell vent is used, then the structure is simple, but the vent may be blocked by component parts during thermal triggering
Solution Approach 1:
The cell vent is divided into two separate layers: a first layer (metal foil) and a second layer (plastic film). This segmentation allows each layer to perform its specific function - the plastic layer responds first to thermal triggering while the metal layer provides structural support and prevents blockage, thereby resolving the contradiction between structural simplicity and reliability.
Solution Approach 2:
The invention uses a composite structure combining two different materials (metal and plastic) with distinct properties. The plastic layer has lower temperature resistance and yields first, while the metal layer maintains structural integrity. This composite approach enables the vent to reliably prevent blockage during thermal events without excessive complexity.
2Speed
If the first layer is made thinner for earlier response, then pressure reduction occurs earlier, but the layer may lack sufficient mechanical strength
Solution Approach 1:
By combining a thin first layer (metal foil) with a second layer (plastic film), the system achieves both early response and sufficient strength. The thin metal layer responds quickly to pressure changes while the plastic layer provides the necessary mechanical support, resolving the contradiction between speed and strength.
Solution Approach 2:
The second layer (plastic film) acts as an intermediary that supports the first layer mechanically while allowing it to respond quickly to thermal triggering. This intermediary structure enables the thin first layer to function at full speed without compromising overall structural integrity.
3Reliability
If the cell vent opens early for pressure reduction, then safety is improved, but water diffusion into the cell increases
Solution Approach 1:
The invention changes the material parameters of the vent layers, specifically using a plastic film with controlled porosity and hydrophobic properties. This allows the vent to open early for pressure relief while the material characteristics prevent water diffusion, resolving the contradiction between safety and water protection.
4Reliability
If a two-stage vent system is implemented, then pressure reduction is more controlled, but the device complexity increases
Solution Approach 1:
The vent system is segmented into two functional layers with distinct response characteristics. The plastic layer responds first at lower temperatures, providing initial pressure relief, while the metal layer responds later or provides structural support. This segmentation achieves controlled pressure reduction without excessive complexity.
Solution Approach 2:
By changing the material parameters (temperature resistance, strength) of each layer, the system achieves two-stage pressure control. The plastic layer has lower melting/softening temperature for early response, while the metal layer has higher temperature resistance for later response or structural support, enabling controlled pressure reduction with minimal added complexity.
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 solution enables orderly pressure reduction and prevents unforeseen occurrences like vent blockage and gas discharge, enhancing safety and reducing the risk of thermal triggering-related failures in lithium-ion energy stores.
Implementation Method 1
the plastic of the second layer responds earlier in the event of thermal triggering than the first layer
Implementation Method 2
In the event of a thermal anomaly above a predefined temperature threshold, the cell vent opens so that pressure can be reduced
Implementation Method 3
the full pressure difference exerts a load on the first layer and also this layer can respond earlier than was the case in the prior art
Implementation Method 4
thermal triggering of the electrochemical energy store takes place
Implementation Method 5
a third plastic barrier at the breaking point prevents water diffusion
Data Source
AI summary
The present disclosure is directed to an electrochemical energy store, a means of transport, a manufacturing method and a cell vent for an electrochemical energy store. In one form a cell vent comprises a first layer comprising a metal and a second layer comprising a first plastic, wherein the first layer and the second layer are arranged successively with respect to a pressure differential on the cell vent.