Cell Assembly Flame Barrier for Battery Thermal Runaway Containment
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Solution Overview
Problem
Battery packs containing electrochemical cells, such as lithium-ion cells, are prone to thermal runaway, which can lead to a cascading effect causing adjacent cells to also enter thermal runaway, resulting in power interruption and collateral damage due to uncontrolled heat propagation.
Innovation Solution
A cell assembly design featuring an electrochemical cell with a ceramic-coated polyethylene terephthalate flame barrier and aramid fiber outer wrap, along with heat plates and a polymeric resin that ruptures to direct gases away during off-gassing events, is used to mitigate thermal runaway by isolating and containing heat and flames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal barrier elements are used to prevent thermal runaway propagation, then safety is improved, but device complexity increases
Solution Approach 1:
The battery pack is divided into multiple cell assemblies, each independently wrapped with thermal barrier elements. This segmentation isolates thermal runaway events to individual cells or small groups of cells, preventing propagation to the entire battery pack while maintaining manageable complexity through modular design
Solution Approach 2:
Thermal barrier elements serve as intermediary components positioned between adjacent electrochemical cells. These barriers (including ceramic-coated polyethylene terephthalate sheets and aramid fiber materials) act as mediators that block thermal energy transfer and flame propagation while allowing the battery pack to maintain its functional structure
2Productivity
If cell assemblies are closely packed to increase energy density, then productivity is improved, but thermal runaway propagation risk increases
Solution Approach 1:
Thermal barrier elements are applied locally at critical interfaces between cell assemblies rather than uniformly throughout the entire battery pack. The barriers are positioned specifically at heat transfer pathways and flame propagation routes, providing targeted protection while minimizing impact on energy density
Solution Approach 2:
The thermal barrier system uses composite materials including ceramic-coated polyethylene terephthalate sheets combined with aramid fiber materials. These composite structures provide enhanced thermal resistance and flame barrier properties in thin profiles, allowing close cell packing while maintaining safety
3Reliability
If thicker thermal barrier elements are used to improve protection, then safety is improved, but volume of stationary object increases
Solution Approach 1:
The thermal barrier system utilizes materials with superior thermal resistance properties that achieve equivalent or superior protection with reduced thickness. Ceramic coatings and aramid fibers provide high thermal stability and flame resistance in thin layers, reducing the volume occupied by barrier elements while maintaining or improving protection levels
Solution Approach 2:
Composite barrier structures combine multiple functional layers (ceramic coating, polyethylene terephthalate substrate, aramid fiber reinforcement) to achieve enhanced thermal performance in thin profiles. This composite approach provides maximum protection with minimum thickness, optimizing the balance between safety and volume
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 effectively prevents the propagation of thermal runaway between adjacent cells, ensuring safe operation and minimizing damage by isolating heat and flames, thereby maintaining power integrity and preventing collateral damage.
Implementation Method 1
a ceramic-coated polyethylene terephthalate flame barrier... to mitigate thermal runaway by isolating and containing heat and flames
Implementation Method 2
aramid fiber outer wrap... to mitigate thermal runaway by isolating and containing heat and flames
Implementation Method 3
a polymeric resin that ruptures to direct gases away during off-gassing events
Data Source
AI summary
A cell assembly group is provided, comprising: a plurality of cell assemblies, each cell assembly including an electrochemical cell and an outer wrap surrounding the cell; a foam sheet positioned adjacent one side of one cell assembly; a plurality of heat plates, each heat plate being positioned between two cell assemblies; and at least one spacer positioned between one heat plate and one cell assembly. Each outer wrap of each cell assembly of the plurality of cell assemblies includes a body having an inner surface that engages a rearward wall of the electrochemical cell of the cell assembly, a first portion having a flame barrier that engages a forward wall of the electrochemical cell of the cell assembly, and a second portion that engages an outer surface of the first portion.