Aircraft Battery Cell Venting Layout for Thermal Runaway Isolation
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Solution Overview
Problem
Existing battery cell designs for aircraft face challenges in managing thermal runaway, as venting products from one cell can ignite neighboring cells, and the weight increase required for safety measures is a concern, especially in aviation where space and weight are critical.
Innovation Solution
A battery cell arrangement with individual compartments and dedicated vent channels, where each compartment has a cover element that opens or is destroyed during thermal runaway, allowing venting products to escape without contacting other cells, and a gas-tight housing with separate venting paths to prevent overpressure and minimize weight increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If battery cells are packed tightly to minimize volume, then the volume of the battery pack is reduced, but the risk of fire propagation to neighboring cells increases due to direct contact with venting products
Solution Approach 1:
The battery pack is divided into multiple fire compartments, each containing one or more battery cells. These compartments are separated by fire-resistant walls that prevent the propagation of flames, hot gases, and debris between adjacent cells. This segmentation allows tight packing of cells within each compartment while maintaining safety barriers between them.
Solution Approach 2:
Fire-resistant walls and thermal barriers are introduced as intermediary structures between adjacent battery cells. These intermediaries absorb and block thermal energy, preventing hot venting products from directly contacting neighboring cells. The barriers include fire-resistant materials and thermal insulation layers that stand between the harmful venting products and vulnerable adjacent cells.
2Reliability
If the housing is hermetically sealed to prevent gas leakage, then safety is improved, but the weight and cost of the housing increase due to required strength and heat resistance
Solution Approach 1:
Instead of requiring the entire housing to be hermetically sealed and fire-resistant, the system segments the battery pack into fire compartments. Each compartment needs only localized fire resistance and pressure containment, allowing the use of lighter materials and thinner walls compared to a fully sealed design. The segmentation distributes the safety requirements across multiple smaller zones rather than demanding universal heavy-duty containment.
Solution Approach 2:
Fire resistance and pressure containment properties are applied locally at critical interfaces between compartments and at venting paths, rather than uniformly across the entire housing. This allows the housing to be optimized with lighter materials in non-critical areas while maintaining necessary safety properties only where thermal and pressure loads are present.
3Volume of moving object
If venting paths are dimensioned for individual cells, then space constraints are addressed, but venting products come in direct contact with other battery cells causing negative effects
Solution Approach 1:
Each fire compartment is equipped with dedicated venting paths that channel hot gases and debris vertically upward within the compartment. The fire-resistant walls extend to contain these venting products, preventing them from spreading to adjacent compartments. This segmented venting approach allows compact horizontal arrangement while maintaining vertical containment of harmful substances.
Solution Approach 2:
The venting strategy transitions from horizontal venting paths that would require large lateral spaces to vertical venting paths that utilize the vertical dimension. Hot gases are directed upward through fire-resistant channels and contained within each compartment's vertical space, eliminating the need for large horizontal clearance between cells while preventing cross-contamination between adjacent compartments.
4Reliability
If cover elements are designed to open during thermal runaway, then venting is enabled, but the structural integrity and sealing of the housing may be compromised
Solution Approach 1:
The cover system is segmented into multiple independent cover elements, each associated with specific vent channels and fire compartments. When thermal runaway occurs in one compartment, only the corresponding cover element opens, while other covers remain intact. This segmentation preserves the structural integrity and sealing of unaffected compartments while enabling necessary venting where needed.
Solution Approach 2:
The cover elements are designed with self-activating mechanisms that respond automatically to thermal and pressure conditions during thermal runaway. Sensors or thermal-mechanical actuators detect the thermal event and trigger cover opening without external intervention, enabling timely venting while maintaining housing integrity under normal operating conditions.
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
This design prevents fire propagation to other cells and reduces the weight of the battery pack by allowing venting products to escape safely without accumulating pressure, meeting stringent aviation safety standards while maintaining a lightweight structure.
Implementation Method 1
Battery cells, such as lithium-ion battery cells, can go into thermal runaway due to external influences or internal faults, during which they may release large amounts of heat, gases and debris.
Implementation Method 2
a venting system is used in battery systems or battery cell arrangements to channel any flames, gases and debris to the outside of the battery system in a controlled way
Data Source
AI summary
A battery cell arrangement (1) for use in an aircraft, includes a plurality of battery cells (2), at least one battery housing (3) enclosing the plurality of battery cells (2), the housing (3) having an opening (3a); and separating elements (4) located inside said battery housing (3), for separating individual battery cells (2) from each other. Each battery cell (2) is associated with a respective vent channel (5) that open to the opening (3a). The vent channels (5) define a number of battery cell compartments, each of which holds a subset of said plurality of battery cells (2) and each of the compartments is closed by a cover element (6) that opens if a battery cell (2) in a corresponding compartment goes into thermal runaway and produces gaseous venting products (GP). An aircraft having such a battery cell arrangement is also provided.