Fire-Resistant Battery Bag Venting to Prevent Thermal Runaway Rupture
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Solution Overview
Problem
Current solutions for storing and transporting high-capacity e-bike lithium-ion batteries are inadequate, as they lack fire and explosion resistance, leading to potential ruptures and dispersal of high-temperature materials during thermal runaway, which can occur during charging or transportation.
Innovation Solution
A fire and explosion-resistant storage and transport bag designed with multiple layers of fire-resistant and thermal insulation materials, featuring high-temperature vents loaded with fire-resistant materials like steel wool to prevent rupture and allow controlled venting of gases, while maintaining physical integrity and blocking flames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aviation grade fire containment bags are used to contain e-bike batteries, then fire resistance is improved, but the bag ruptures due to rapid pressure buildup during thermal runaway
Solution Approach 1:
The invention extracts the harmful pressure buildup by introducing a controlled venting mechanism that releases gases during thermal runaway. The vent allows selective removal of pressurizing substances while maintaining the fire containment function, preventing bag rupture without compromising fire resistance.
Solution Approach 2:
The vent's melting point parameter is specifically selected to be higher than the thermal runaway temperature but lower than the fire resistance requirement. This parameter differentiation allows the vent to open at controlled temperatures to relieve pressure while the bag structure maintains fire resistance at higher temperatures.
2Reliability
If the bag is made fully fire resistant to contain thermal runaway, then fire safety is improved, but the bag becomes rigid and cannot be folded for portability
Solution Approach 1:
The bag employs local quality differentiation where different regions have different fire resistance properties. The vent area has lower fire resistance (lower melting point) to allow controlled opening, while the main bag structure maintains high fire resistance. This localized variation enables both portability through folding and fire safety during thermal runaway.
3Stress or pressure
If vents are opened to release pressure during thermal runaway, then pressure buildup is reduced, but flames may escape and cause external ignition
Solution Approach 1:
The invention introduces an intermediary substance (fire suppressant agent) that mediates between the internal thermal runaway environment and the external atmosphere. This agent is released through the vent along with gases, suppressing flames and preventing fire propagation externally while allowing pressure relief.
Solution Approach 2:
The venting process, which could potentially spread fire, is converted into a beneficial action by simultaneously releasing fire suppressant agents. The harmful flame escape is transformed into a controlled release that suppresses fire, turning the potential harm of opening the vent into a benefit for external fire prevention.
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 bag effectively contains thermal runaway events in e-bike batteries by preventing rupture and allowing controlled venting of gases, reducing the risk of explosion and damage, and maintaining structural integrity during thermal events.
Implementation Method 1
the steel wool is allowed to react with venting products through oxidation. Beneficially, fairly aggressive materials may be at least partially captured by the steel wool through the oxidation thereof.
Implementation Method 2
Steel wool with a melting temperature of at least 1,400°C can be considered such a fire-resistant material forming a filter
Implementation Method 3
the body of the bag is formed of multiple layers of fire resistant and thermal insulation materials designed for resisting the thermal energy contained in a 50% charged 750 Wh Lithium-ion battery
Implementation Method 4
the bag comprises a high temperature vent suitable for venting gasses from the inner volume to the environment, said vent being loaded with a fire resistant material forming a filter. This prevents the bag from inflating to the point of rupture
Data Source
Figure 1
AI summary
A fire resistant safety bag comprising a body that defines an internal volume for carrying and storing a lithium ion battery having a maximum energy capacity between 250-1250 Wh, such as 750 Wh, wherein the body of the bag is formed of multiple layers of fire resistant material designed for resisting the thermal energy contained in a 50% charged 750 Wh Lithium-ion battery, and wherein the layers of fire resistant material are jointly flexible for allowing one end of the bag to be folded between an open and a closed position for reversibly closing off the internal volume against manual access, wherein the bag comprises a high temperature first vent suitable for venting gasses from the inner volume to the environment, said first vent being loaded with a fire resistant material forming a filter.