Temperature-Triggered SOC Reduction in Li-Ion Cells for Thermal Runaway
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Solution Overview
Problem
Lithium-ion batteries are prone to thermal runaway (TR) due to thermal propagation (TP), which can lead to significant property damage, injury, or loss of life, especially in high-energy density cells like those containing silicon or lithium metal, where thermal runaway can spread rapidly across adjacent cells.
Innovation Solution
A safety-enhancement state-of-charge reduction device (SOCD) is integrated into the battery, which includes temperature-sensitive elements that create a low-resistance path within the cell enclosure to rapidly lower the state-of-charge by shorting the electrodes when a specific temperature threshold is reached, preventing further thermal propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high energy density materials (silicon anode, lithium metal, high-nickel cathode) are used to increase battery capacity, then battery energy density is improved, but thermal runaway risk and thermal propagation speed increase
Solution Approach 1:
The patent incorporates safety devices (insulation paper wrapping and state-of-charge reduction devices) into the battery cell structure before assembly. These devices are pre-positioned to activate automatically when thermal runaway conditions develop, shorting the cell to reduce state of charge and prevent thermal propagation to adjacent cells, thereby addressing the thermal runaway risk inherent in high energy density materials
Solution Approach 2:
The patent uses insulation paper wrapping as an intermediary barrier between adjacent battery cells. This wrapping material physically isolates cells from each other, preventing direct thermal and electrical contact that would otherwise allow rapid thermal propagation between cells in high energy density battery packs
2Reliability
If state-of-charge reduction devices are integrated into battery cells to prevent thermal propagation, then safety is improved, but device complexity increases
Solution Approach 1:
The state-of-charge reduction device is designed with temperature-sensitive elements that automatically trigger the shorting function when thermal runaway conditions are detected. The device serves itself by using the thermal energy from the runaway condition to activate the safety mechanism, eliminating the need for external sensors, power sources, or control systems
Solution Approach 2:
The safety device utilizes phase transitions of temperature-sensitive elements (such as melting or deformation at specific temperatures) to automatically trigger the state-of-charge reduction mechanism. This phase change-based activation simplifies the device structure by eliminating complex sensing and control electronics
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 SOCD effectively reduces the risk of thermal propagation and thermal runaway by discharging the cell safely before it reaches critical temperatures, enhancing safety in lithium-ion batteries.
Implementation Method 1
temperature-sensitive elements that create a low-resistance path within the cell enclosure to rapidly lower the state-of-charge by shorting the electrodes when a specific temperature threshold is reached
Implementation Method 2
create a low-resistance path within the cell enclosure to rapidly lower the state-of-charge by shorting the electrodes
Data Source
AI summary
This disclosure describes safety-enhancement state-of-charge (SOC) reduction devices for propagation resistant lithium-ion batteries. The SOC reduction device is added between the electrodes of a lithium-ion cell. Before thermal runaway can occur, the SOC reduction device shorts the electrodes according to a trigger temperature.