Battery Pack Fire Extinguishing Agent Venting Mechanism
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Solution Overview
Problem
Conventional secondary battery packs face safety issues due to insufficient venting techniques, which fail to adequately reduce internal pressure and temperature during abnormal operation states, leading to potential explosions and fires, especially as battery capacity and energy density increase.
Innovation Solution
A battery pack design incorporating a fire extinguishing agent, such as liquid perfluoroketone, disposed in a cavity between two pack cases, with a venting mechanism that allows the agent to flow into the pack when critical pressure is reached, directly contacting the electrode assembly to reduce temperature and prevent ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If conventional venting techniques are used to relieve high pressure, then pressure reduction is achieved, but temperature reduction is insufficient leading to potential ignition
Solution Approach 1:
The battery pack structure is segmented into an inner pack case containing the electrode assembly and an outer pack case, with a cavity formed between them. This segmentation allows the fire extinguishing agent to be stored separately in the cavity while maintaining the integrity of the battery components, enabling independent temperature control without affecting pressure relief functionality.
Solution Approach 2:
A fire extinguishing agent is introduced as an intermediary substance stored in the cavity between the inner and outer pack cases. When thermal runaway occurs, this agent is discharged through a discharge hole into the inner pack case, directly contacting the electrode assembly to suppress combustion and reduce temperature, thereby addressing the insufficient temperature reduction of conventional venting systems.
2Quantity of substance
If battery capacity and energy density are increased, then energy output is improved, but safety risk increases due to insufficient venting capability
Solution Approach 1:
The fire extinguishing agent is pre-stored in the cavity between the inner and outer pack cases before any thermal runaway event occurs. The discharge hole is pre-positioned on the inner pack case, ready to release the agent when needed. This preliminary preparation ensures that when high-capacity batteries experience thermal runaway, the suppressant is immediately available to counteract the reaction, enhancing safety without compromising energy density.
Solution Approach 2:
The cavity structure acts as a cushioning space that accommodates the fire extinguishing agent in advance. This beforehand cushioning arrangement ensures that when thermal runaway occurs in high-capacity batteries, the suppressant can be rapidly deployed to cushion and mitigate the harmful effects, providing superior safety protection compared to conventional venting systems.
3Reliability
If a cavity is formed between pack cases to store fire extinguishing agent, then safety is improved, but device complexity increases
Solution Approach 1:
The cavity between the inner and outer pack cases serves multiple functions: it provides structural spacing for thermal insulation, acts as a storage space for the fire extinguishing agent, and functions as a discharge pathway when thermal runaway occurs. This multi-functionality reduces the need for separate safety components, thereby improving safety without proportionally increasing device complexity.
Solution Approach 2:
The inner pack case is nested within the outer pack case, with the fire extinguishing agent stored in the cavity between them. This nested structure efficiently utilizes the available space, allowing the safety system to be integrated within the existing battery pack architecture rather than adding external components, thus minimizing the increase in device complexity while enhancing safety.
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 effectively reduces the risk of ignition and explosion by directly cooling the electrode assembly and rapidly reducing internal pressure and temperature, providing superior safety compared to conventional venting systems.
Implementation Method 1
the fire extinguishing agent may be a liquid perfluoroketone which vaporizes at a fixed temperature
Data Source
AI summary
A battery pack includes an electrode assembly having a cathode, an anode, and a separator interposed therebetween, a first pack case having the electrode assembly and an electrolyte disposed therein, a second pack case with the first pack case disposed therein and a portion of the interior surface separated from the first pack case exterior surface, a fire extinguishing agent disposed between the exterior surface of the first pack case and the interior surface of the second pack case and a cap assembly that simultaneously seals an open surface of the first and second pack cases when the first pack case is disposed in the second pack case. A first venting portion is configured to open to enable the fire extinguishing agent to flow into the interior of the first pack case when the pressure within the first pack case is equal to or greater than a critical pressure.