Battery Pack Thermal Spread Inhibition Through Melt-Open Water Injection
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Solution Overview
Problem
Existing battery packs face challenges in effectively preventing the spread of flames and thermal runaway in lithium secondary battery cells, as current methods require additional space and resources, and may not efficiently extinguish fires or cool adjacent cells.
Innovation Solution
A battery pack design incorporating a water tank and a sealing member with a low melting point, where the coolant is sprayed through a through-hole formed in the pack case and crossbeam to directly inject coolant into an ignited battery cell, preventing thermal energy transfer to adjacent cells without increasing the pack's size or weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate watering device is used to inject water into the battery pack, then fire extinguishing function is provided, but additional facilities and space are required
Solution Approach 1:
The patent merges the fire extinguishing function with existing battery pack structural components (pack case and crossbeam) by forming through-holes directly in these parts. This eliminates the need for separate watering devices and dedicated fire suppression facilities, thereby providing fire extinguishing capability while avoiding additional space requirements.
Solution Approach 2:
The battery pack structure itself serves the dual purpose of structural support and fire suppression. The pack case and crossbeam, which are already present for mechanical support, are modified to include through-holes that enable direct water injection. This self-service approach allows the structure to perform both its original function and fire extinguishing without requiring separate dedicated components.
2Reliability
If fire extinguishing agent is disposed in empty space of battery pack, then fire can be suppressed, but energy density decreases and agent may not reach ignition point
Solution Approach 1:
The patent extracts the fire suppression function from the empty space within the battery pack and relocates it to the structural boundaries (pack case and crossbeam). By forming through-holes in these external structures, the system enables direct water injection to the ignition point without requiring storage of fire extinguishing agents within the pack's internal empty space, thereby maintaining energy density while ensuring effective fire suppression.
Solution Approach 2:
The pack case and crossbeam act as intermediaries that facilitate direct water delivery to the battery cells. Instead of storing fire extinguishing agents in empty space and relying on their dispersion, the patent uses the structural components as conduits to deliver water directly to the ignition point through the through-holes, ensuring effective fire suppression without compromising energy density.
3Reliability
If compressed gas and nozzle are added for fire extinguishing agent injection, then fire extinguishing function is improved, but device complexity and expense increase
Solution Approach 1:
The patent employs water under pressure from the water tank as a self-service mechanism to achieve effective fire extinguishing. The high-pressure water flow naturally propels itself through the through-holes in the pack case and crossbeam without requiring compressed gas systems, nozzles, or complex injection mechanisms. This approach maintains fire extinguishing efficiency while dramatically reducing device complexity and component requirements.
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 rapidly cools ignited battery cells, inhibits thermal runaway, and reduces production costs by using water as a coolant, while maintaining structural safety and minimizing weight, effectively preventing flame spread even in large-capacity packs.
Implementation Method 1
a sealing member (210) added to the through-hole (220), the sealing member (210) being made of a material that is melted by high-temperature gas or sparks discharged from the battery cell (130)
Implementation Method 2
it is possible to exactly inject the coolant into the ignited battery cell... rapidly cools ignited battery cells, inhibits thermal runaway
Data Source
AI summary
A battery pack includes a battery cell stack formed by a plurality of stacked battery cells, a battery module housing configured to wrap the other outer surfaces of the battery cell stack excluding a first surface and a second surface, from which electrode leads protrude, a water tank configured to supply a coolant to the battery cell or the battery module housing, and a battery pack case configured to receive a plurality of battery module housings. The battery pack case includes a pack case space portion located adjacent to the first surface and a crossbeam located adjacent to the second surface, whereby, when fire breaks out in the battery cell, it is possible to rapidly and accurately prevent spread of flames of the ignited battery cell.