Thermally Reactive Capsule for Early Li-Ion Thermal Runaway Detection
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Solution Overview
Problem
Conventional methods for detecting thermal runaway in batteries, such as gas sensors, are ineffective in detecting early stages of the condition, as they only activate once irreversible damage has occurred, rendering them unable to prevent cell damage.
Innovation Solution
A thermally reactive capsule coupled to battery cells, containing a volatile organic compound (VOC) with a boiling point below a threshold temperature, which vaporizes and opens pressure relief devices upon reaching this temperature, releasing gas detectable by a sensor to indicate potential thermal runaway before damage occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gas detection sensor is used to detect thermal runaway by detecting gas vented from a battery unit, then thermal runaway can be detected, but the battery cell has already suffered irreversible damage by the time gas venting occurs
Solution Approach 1:
The thermally reactive capsule performs preliminary action by detecting temperature increase at an early stage before gas venting occurs. The capsule is positioned to directly contact the battery cell, allowing it to sense temperature rise and trigger the VOC release mechanism before irreversible damage happens, thus providing early warning of thermal runaway
Solution Approach 2:
The thermally reactive capsule acts as an intermediary between the battery cell and the gas sensor. It contains a VOC that releases upon temperature increase, creating a detectable gas signal that indicates thermal runaway conditions before the battery cell itself vents gas, thereby enabling earlier detection
2Loss of time
If the boiling point of the VOC is set below the threshold temperature to enable early detection, then early-stage thermal runaway can be detected, but the VOC may vaporize before the battery reaches dangerous temperature levels
Solution Approach 1:
The system changes the parameter of VOC selection by choosing compounds with specific boiling points that fall within a controlled range (50°C to 100°C). This parameter optimization allows the VOC to vaporize at temperatures that provide early detection while remaining below the battery's dangerous threshold temperature, balancing early detection with accurate thermal runaway indication
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
Enables early detection of thermal runaway, allowing for preventive measures to avoid permanent battery cell damage by using a thermally reactive capsule that releases VOC gas upon reaching a temperature indicative of impending thermal runaway, which is then detected by a sensor.
Implementation Method 1
a capsule shell comprising a thermally conductive material that transfers heat from a surface of a battery cell to the capsule shell
Implementation Method 2
the vaporization of the VOC comprises a conversion of the VOC from liquid state to gas state
Implementation Method 3
the vaporization is caused by a transfer of heat from the surface of the battery cell to the capsule shell, wherein the heat causes the VOC to reach or exceed the boiling point of the VOC
Implementation Method 4
one or more pressure relief devices configured on a surface of the capsule shell, wherein pressure generated by vaporization of the VOC causes opening of the one or more pressure relief devices
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A thermally reactive capsule coupled to a battery cell, the thermally reactive capsule comprising a capsule shell comprising a thermally conductive material that transfers heat from a surface of the battery cell to the capsule shell, a volatile organic compound ("VOC") stored within a cavity of the capsule shell, wherein the VOC is in a liquid state and at a temperature below boiling point of the VOC, and the boiling point of the VOC is below a threshold temperature. The thermally reactive capsule further comprising one or more pressure relief devices configured on a surface of the capsule shell, wherein pressure generated by vaporization of the VOC causes opening of the one or more pressure relief devices.