Cylindrical Cell Barrier Gaps for Thermal Runaway Isolation
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Solution Overview
Problem
Aircraft battery packs face the risk of thermal runaway propagation, which can lead to catastrophic failures due to undetectable defects or manufacturing variability, posing severe consequences in aerospace applications where weight and power density are critical considerations.
Innovation Solution
Incorporating anti-propagation barriers with strategically sized gaps around cylindrical battery cells to contain debris and prevent failure propagation, while optimizing power density and weight through the use of thin barrier walls and composite materials, and employing flow control devices to direct vented media away from vulnerable areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anti-propagation barriers are added around battery cells, then thermal runaway propagation is prevented, but device complexity and weight increase
Solution Approach 1:
The battery pack is divided into multiple isolated cell groups, each surrounded by its own barrier wall. This segmentation prevents thermal runaway from propagating between groups while maintaining individual cell autonomy. The barrier walls create discrete containment zones that isolate failures locally.
Solution Approach 2:
Thin barrier walls are used to provide thermal isolation without adding significant weight or complexity. These thin film structures are sufficient to contain thermal runaway events while minimizing the impact on overall pack density and weight, addressing the contradiction between protection and added complexity.
2Weight of moving object
If barrier walls are made thin to reduce weight, then power density is improved, but structural strength and containment capability deteriorate
Solution Approach 1:
The barrier walls are constructed from composite materials that provide high strength-to-weight ratio. These composite structures deliver the necessary mechanical strength and thermal containment capability while keeping the wall thickness minimal, thus reducing overall weight without compromising containment effectiveness.
Solution Approach 2:
The barrier wall design optimizes parameters such as thickness, material composition, and geometric configuration to achieve the minimum required strength while minimizing weight. By carefully controlling these parameters, the barrier provides adequate containment with minimal mass penalty.
3Weight of moving object
If cells are arranged densely to improve power density, then weight is reduced, but thermal runaway propagation risk increases
Solution Approach 1:
The dense cell arrangement is organized into discrete groups separated by barrier walls. This segmentation allows high cell density within each group while preventing thermal runaway from spreading to adjacent groups, thus maintaining both high power density and safety.
Solution Approach 2:
The barrier walls act as intermediary structures between densely packed cell groups. These intermediaries provide thermal isolation necessary to prevent propagation while allowing the cells to be arranged as densely as possible within each confined group, maximizing power density without sacrificing safety.
4Reliability
If gaps are defined between barrier walls and cells, then thermal isolation is improved, but volume and power density decrease
Solution Approach 1:
The gap dimensions between barrier walls and cells are precisely controlled within optimized ranges. This parameter optimization ensures sufficient thermal isolation to prevent propagation while minimizing the volume consumed by gaps, thus maintaining high power density.
Solution Approach 2:
The barrier wall design implements different gap sizes at different locations based on local thermal risk assessment. Critical areas have larger gaps for enhanced isolation, while less critical areas have minimal gaps, optimizing the balance between thermal isolation and volume utilization.
Data Source
AI summary
A battery pack includes: a plurality of cylindrical battery cells, each one of the plurality of cells having a cylindrical outer cell wall that extends in a z-direction between opposed first and second ends of the cell; a carrier structure that locates the battery cells relative to one another and arranges them in an array in an x-y plane perpendicular to the z-direction; and a plurality of barriers for preventing propagation of thermal runaway between cells of the array, each one of the plurality of barriers forming a barrier wall that surrounds a group of one or more of the cells. A gap is defined between the barrier wall of each respective barrier and the outer cell wall of each of the respective one or more cells enclosed by the respective barrier.