Memory-Alloy Explosion-Proof Valve for Thermal Runaway Venting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing explosion-proof valves for lithium batteries are ineffective in controlling thermal runaway due to high welding temperatures causing deformation and phase changes, and they only function when internal pressure reaches a high value, failing to prevent accidents.
Innovation Solution
An explosion-proof valve cover made of memory alloy material that deforms at a preset temperature threshold, forming a gap with the valve seat to release gas, and is connected non-welded to ensure no phase change, with a stable connection through injection molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the memory metal alloy sheet is directly welded to the battery top cover, then the explosion-proof valve can be installed, but the welding temperature causes phase change and deformation of the memory alloy sheet, making it ineffective
Solution Approach 1:
The explosion-proof valve is divided into separate components: the memory alloy sheet is not directly welded to the top cover, but instead is positioned within the explosion-proof valve assembly which is then welded as a unit. This segmentation isolates the temperature-sensitive memory alloy from direct exposure to welding heat.
Solution Approach 2:
The explosion-proof valve body acts as an intermediary structure between the top cover and the memory alloy sheet. The valve body is welded to the top cover, while the memory alloy sheet is held in position by the valve structure itself, preventing direct thermal contact during welding operations.
2Reliability
If the explosion-proof valve uses traditional high-pressure rupture design, then it can release gas, but it only functions when internal pressure reaches a high value, failing to control early-stage thermal runaway
Solution Approach 1:
The memory alloy sheet's activation temperature is changed from a high-pressure mechanical rupture threshold to a lower thermal activation point. By utilizing the temperature-dependent shape memory effect, the valve activates at temperatures characteristic of early thermal runaway rather than requiring high pressure buildup.
Solution Approach 2:
The memory alloy sheet undergoes a phase transition at its specific activation temperature, changing from a high-temperature phase to a low-temperature phase. This phase change causes the sheet to deform and create an opening, enabling pressure relief at the appropriate thermal stage of battery failure.
3Ease of operation
If the explosion-proof valve cover is made of memory alloy material for temperature-responsive deformation, then it can form gaps for gas discharge, but welding temperature causes unwanted phase change and deformation
Solution Approach 1:
The valve cover assembly is segmented into the permanent housing structure and the removable memory alloy sheet. This allows the housing to be welded and assembled at high temperatures while the memory alloy sheet is installed separately at lower temperatures where it can maintain its precise dimensions and activation characteristics.
Solution Approach 2:
The memory alloy sheet is pre-installed into the explosion-proof valve assembly during manufacturing, allowing it to be acclimated and positioned correctly before final assembly. This preliminary installation ensures the sheet is not exposed to subsequent welding operations that would cause unwanted deformation.
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
Ensures effective pressure relief and prevents thermal runaway by reducing the impact of welding temperatures, maintaining structural integrity and enhancing safety without phase changes.
Implementation Method 1
the explosion-proof valve cover is made of the memory alloy material, so that when the internal temperature of the lithium battery is higher than the preset temperature control threshold, the explosion-proof valve cover may deform
Implementation Method 2
the welding temperature is usually higher than 200°C. At such temperature, the memory alloy sheet has a phase change and generates deformation
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Disclosed are an explosion-proof valve, a battery top cover and a lithium battery. The explosion-proof valve specifically includes an explosion-proof valve cover (10) and an explosion-proof valve seat (30), the explosion-proof valve seat (30) being provided with a valve hole; the explosion-proof valve seat (30) includes a first inner ring part (31) and a first outer ring part (32), the explosion-proof valve cover (10) being connected to the first inner ring part (31) in a non-welded manner and sealing the valve hole, wherein the explosion-proof valve cover (10) deforms at a temperature higher than a preset temperature control threshold, and a crack or a gap is formed between the deformed explosion-proof valve cover (10) and the explosion-proof valve seat (30); therefore, high-temperature gas is discharged from the crack or the gap to avoid accidents caused by thermal runaway of the lithium battery; the explosion-proof valve seat (30) is welded to the battery top cover and other components, and the explosion-proof valve seat (30) is connected to the explosion-proof valve cover (10) in a non-welded manner, so that the influence of the welding temperature on the explosion-proof valve cover (10) may be reduced, it is ensured that the explosion-proof valve cover (10) has no phase change when the explosion-proof valve is welded to the battery top cover and other components, and the explosion-proof effect is ensured.