Battery Pack Thermal Runaway Prevention via Phase Change Cooling
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Solution Overview
Problem
Existing battery pack systems face challenges in effectively controlling thermal runaway, as heat propagation from one battery cell to others can lead to rapid temperature increases and potentially catastrophic failures, with existing solutions either relying on fluid discharge that requires large amounts of coolant or limited insulation liquids that struggle to absorb heat effectively.
Innovation Solution
A battery pack system with a battery module immersed in a filling liquid and equipped with a cooling pipe that melts at a preset temperature to release coolant, utilizing a coolant with higher latent heat of vaporization than the filling liquid, which absorbs heat through phase change to control temperature and inhibit thermal runaway propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If battery cells are arranged very closely to pursue energy density, then energy density is improved, but heat accumulation occurs and thermal runaway risk increases
Solution Approach 1:
The patent introduces filling liquid as an intermediary substance between closely arranged battery cells. This liquid mediator absorbs heat from individual cells and distributes it throughout the battery module, preventing localized heat accumulation while maintaining high energy density through close cell arrangement.
Solution Approach 2:
The patent utilizes phase transition of the filling liquid (from liquid to vapor) as a heat absorption mechanism. When thermal runaway occurs, the liquid fills the expansion chamber and undergoes phase change, absorbing large amounts of heat through latent heat of vaporization, thereby controlling temperature rise and preventing thermal runaway propagation.
2Device complexity
If fire extinguishing agent is injected only after open flame detection, then device complexity is reduced, but thermal runaway propagation cannot be prevented in early stage
Solution Approach 1:
The patent employs temperature sensors that automatically trigger the phase change heat absorption mechanism when thermal runaway is detected. The system serves itself by using the inherent phase transition properties of the filling liquid without requiring complex external fire extinguishing systems, achieving both simplicity and reliability.
3Use of energy by moving object
If radiating panels are used for heat radiation, then heat dissipation efficiency is improved, but thermal conduction rapidly transfers heat between cells during thermal runaway
Solution Approach 1:
The filling liquid acts as a thermal intermediary that replaces direct thermal conduction through radiating panels. During normal operation, it provides gentle heat dissipation; during thermal runaway, it absorbs heat through phase change without rapidly conducting it to neighboring cells, thus preventing thermal runaway propagation while maintaining heat dissipation efficiency.
4Temperature
If large amount of coolant is discharged through breach, then thermal control effect is improved, but weight and volume of the system increase
Solution Approach 1:
The patent utilizes the phase transition of a relatively small amount of filling liquid from liquid to vapor to absorb large amounts of heat. The latent heat of vaporization provides powerful thermal control effect without requiring large quantities of coolant, thereby avoiding excessive weight and volume increases while maintaining effective thermal runaway 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 system effectively isolates air to prevent open flames, reduces heat generation, and rapidly absorbs heat to control battery module temperature, preventing further thermal runaway and ensuring the safety and longevity of the battery pack.
Implementation Method 1
the cooling pipe is configured to absorb heat and melt to form a breach after reaching a preset temperature
Implementation Method 2
the cooling pipe is configured to absorb heat and melt to form a breach after reaching a preset temperature
Implementation Method 3
The coolant is water or aqueous solution, and the phase-transition temperature of the coolant is in the range from 70 to 150 Celsius degree
Implementation Method 4
the latent heat of vaporization of the coolant is higher or equal to the latent heat of vaporization of the filling liquid
Implementation Method 5
the battery box is further filled with a filling liquid, and the battery module is at least partially immersed in the filling liquid
Data Source
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AI summary
The present invention is intended to provide a battery pack and a battery pack system. The battery pack comprises a battery box and a battery module. The battery module is disposed in the battery box. The battery module consists of a plurality of battery cells. The battery box is further filled with confining liquid. The battery module is at least partially soaked into the confining liquid. At least one cooling pipeline is disposed in the battery box. At least part of the cooling pipeline is molten and broken after reaching a pre-set temperature. The cooling pipeline is filled with cooling liquid. The vaporization latent heat of the cooling liquid is higher than or equal to the heat capacity or vaporization latent heat of the confining liquid. The technical solution provided by the present invention can effectively inhibit propagation of thermal runaway of a battery pack, and can save the interior space of a vehicle, thereby improving the energy density of the battery pack.