Battery Module Expansion Members for Thermal Runaway Isolation
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Solution Overview
Problem
Lithium secondary battery modules are vulnerable to thermal events, which can lead to fires or explosions due to uncontrolled heat and gas generation, posing risks to safety and property when densely arranged in narrow spaces, especially in large battery packs used in electric vehicles.
Innovation Solution
A battery module design incorporating an expansion member, such as a phase-change material, that fills empty spaces within the module case upon heat exposure, and a fire extinguishing member to release extinguishing materials, along with venting hole closure by the expansion member to prevent oxygen introduction and flame propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If battery cells are densely arranged in a narrow space to increase capacity, then productivity and energy density are improved, but safety deteriorates due to increased vulnerability to thermal events and thermal propagation
Solution Approach 1:
The battery pack is divided into multiple battery modules, each independently equipped with expansion members. This segmentation allows thermal isolation between modules, preventing thermal propagation while maintaining high density arrangement. The expansion members create thermal barriers within each module without requiring large overall spacing.
Solution Approach 2:
Expansion members filled with phase-change material serve as intermediary elements between battery cells. These intermediaries absorb thermal energy through phase change, acting as thermal buffers that prevent direct thermal contact between cells while occupying minimal space, thus maintaining high packing density.
2Reliability
If expansion members are added to fill empty spaces and suppress thermal propagation, then safety is improved, but device complexity increases
Solution Approach 1:
The expansion members utilize phase-change material that automatically changes physical state (parameter) in response to temperature. This passive parameter-based response eliminates the need for complex active control systems, sensors, or power supplies, maintaining structural simplicity while achieving thermal safety.
Solution Approach 2:
The phase-change material in expansion members provides self-regulating thermal protection without external intervention. When thermal events occur, the material automatically undergoes phase change to absorb heat and fill gaps, providing self-service safety functionality that reduces system complexity.
3Reliability
If phase-change material is used in expansion members to absorb thermal energy, then thermal runaway propagation is prevented, but weight of the battery system increases
Solution Approach 1:
The expansion members utilize phase transitions of the filling material to absorb thermal energy during thermal events. This phase-change mechanism provides high thermal energy absorption capacity per unit mass, effectively preventing thermal propagation while minimizing the additional weight compared to conventional thermal management materials.
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 solution effectively suppresses fires and prevents thermal runaway propagation by filling empty spaces, blocking oxygen introduction, and extinguishing flames, thereby enhancing safety during thermal events in battery modules and packs.
Implementation Method 1
an expansion member located in the module case, and configured to fill at least a part of an empty space in the module case by being expanded in volume when heat is supplied
Implementation Method 2
The expansion member may include a phase-change material
Data Source
AI summary
A battery module has an improved structure to improve safety when a thermal event occurs in the battery module. A battery module includes a cell assembly including one or more battery cells, a module case having an inner space in which the cell assembly is accommodated, and an expansion member located in the module case, and configured to fill at least a part of an empty space in the module case by being expanded in volume when heat is supplied.