eVTOL Battery Assembly With Ejecta Barriers and Directed Venting
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Solution Overview
Problem
Electric vertical take-off and landing (eVTOL) aircraft face challenges with thermal runaway in battery cells, leading to uncontrolled heating and potential conflagration, as materials vented from one cell can ignite upon contact with neighboring cells, causing a positive feedback loop.
Innovation Solution
A stack battery pack design featuring pouch cells aligned such that their bottom and top surfaces are in contact, with an ejecta barrier and vent system to contain and vent cell ejecta, preventing it from interacting with adjacent cells and reducing the risk of thermal runaway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If battery cells are placed in close proximity to maximize energy density, then the energy storage capacity is improved, but the risk of thermal runaway spreading to adjacent cells increases
Solution Approach 1:
The battery pack is divided into multiple modules, each containing battery cells arranged in series. These modules are separated by fire-resistant barriers that prevent thermal runaway from propagating between modules, thus allowing high cell density while maintaining safety through spatial segmentation.
Solution Approach 2:
Fire-resistant barriers and thermal insulation materials are introduced as intermediary elements between adjacent battery modules. These intermediaries absorb and block heat transfer, preventing the thermal runaway chain reaction from spreading to neighboring cells while allowing the battery pack to maintain high energy density.
2Reliability
If battery cells are vented to release pressure during thermal runaway, then the safety of individual cells is improved, but the vented materials can ignite adjacent cells causing conflagration
Solution Approach 1:
The harmful combustible materials and gases are extracted from the battery cell through controlled venting mechanisms. These vented materials are directed away from adjacent cells through strategically positioned vent channels and fire-resistant barriers, preventing ignition of neighboring cells while maintaining individual cell safety.
Solution Approach 2:
The venting system converts the harmful thermal runaway pressure and gases into a controlled release mechanism. By directing the vented materials through fire-resistant barriers and away from adjacent cells, the system transforms the potentially catastrophic uncontrolled explosion into a managed safety feature that protects the overall battery pack.
3Object-affected harmful factors
If fire-resistant barriers are installed between battery modules, then the prevention of thermal runaway spread is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The fire-resistant barriers are designed to serve multiple functions: they act as thermal insulation barriers, structural support elements for the battery pack, and mounting surfaces for electrical connections. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while maintaining effective thermal isolation.
Solution Approach 2:
The fire-resistant barrier structure is merged with the mechanical support framework of the battery pack. By integrating the thermal protection function into the existing structural design, the patent avoids adding separate complex barrier systems, thus maintaining manufacturing simplicity while achieving effective thermal runaway containment.
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 isolates and vents cell ejecta, preventing the spread of thermal runaway and ensuring the safety and reliability of eVTOL batteries by containing combustible materials and electrolyte vapors, thereby enhancing the safety and efficiency of eVTOL aircraft operations.
Implementation Method 1
an ejecta barrier located between the first pouch cell and the second pouch cell, wherein the ejecta barrier is configured to be substantially impermeable to a cell ejecta from the first pouch cell
Implementation Method 2
a vent configured to vent the cell ejecta
Data Source
AI summary
The disclosure provides a battery assembly for an electric aircraft. The battery assembly includes at least one cell having a plurality of surfaces shaped to enclose a battery therein. At least one of the plurality of surfaces includes an ejecta barrier shared between the cell and an adjacent cell and defining a boundary therebetween. The ejecta barrier supports the at least one cell and the adjacent cell and including an ablative material configured to prevent ejecta from passing therethrough. A vent is coupled to an interior of the at least one cell through another one of the plurality of surfaces. The vent is shaped to remove battery ejecta from the cell and oriented away from the ejecta barrier.