Battery Pack Thermal Runaway Mitigation via Metallic Venting Layer
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Solution Overview
Problem
Lithium batteries in distress beacons are prone to thermal runaway, leading to potential explosions and fires, posing a significant safety risk due to uncontrolled temperature increases and gas release.
Innovation Solution
A battery pack design with a protective casing featuring venting holes, a metallic layer for heat absorption, and partition walls to isolate cells, which directs gases through a permeable path to prevent flame spread and allows pressure release, using metallic materials like metal wires or foam to extinguish flames and absorb explosions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid protective casing is used to contain lithium cells, then mechanical protection is improved, but thermal runaway risks increase due to trapped heat and pressure
Solution Approach 1:
The protective casing is segmented into multiple functional layers: an outer rigid casing for mechanical protection, an intermediate metallic layer (steel wool or mesh) for heat absorption and flame inhibition, and an inner plastic layer for electrical insulation. This segmentation allows each layer to address specific hazards independently while working together to mitigate thermal runaway risks.
Solution Approach 2:
A metallic layer (steel wool or mesh) is introduced as an intermediary between the lithium cells and the external environment. This intermediate layer serves multiple functions: absorbing heat, inhibiting flame propagation, and allowing controlled gas venting, thereby mediating between the confined battery space and the outside world to reduce thermal runaway hazards.
2Quantity of substance
If cells are positioned in parallel layout to maximize energy density, then space utilization is improved, but thermal propagation risk increases between adjacent cells
Solution Approach 1:
The battery pack is divided into separate cell compartments with plastic partition walls between adjacent cells. This segmentation physically isolates cells from each other, preventing thermal runaway in one cell from propagating to neighboring cells, while still allowing parallel arrangement to maintain energy density.
Solution Approach 2:
Different regions of the battery pack have different properties: the spaces between cells are filled with heat-absorbing metallic material and electrical insulation, while the cells themselves maintain their high-energy-density configuration. This local differentiation allows adjacent cells to be closely spaced for density while being protected by localized safety features.
3Stress or pressure
If venting holes are added to release pressure during thermal runaway, then gas release is improved, but flame propagation risk increases
Solution Approach 1:
The metallic layer (steel wool or mesh) acts as an intermediary in the venting path, allowing gases to escape through its porous structure while the metal fibers absorb heat and inhibit flame propagation. This intermediary enables pressure relief without direct flame release to the external environment.
Solution Approach 2:
The metallic layer is implemented as a porous material (steel wool or mesh) that allows gas permeation while providing heat absorption and flame inhibition. The porous structure enables controlled venting of pressure while the metal matrix prevents flame passage, solving the contradiction between pressure release and flame containment.
4Object-affected harmful factors
If a thick metallic layer is used to absorb heat and extinguish flames, then thermal protection is improved, but device weight increases
Solution Approach 1:
Instead of a solid thick metallic layer, the invention uses porous metallic materials (steel wool or mesh) that provide high surface area for heat absorption with minimal mass. The porous structure allows gas permeation while the metal fibers provide thermal protection, achieving effective heat absorption without excessive weight.
Solution Approach 2:
The protective structure is implemented as a composite of multiple materials with different functions: rigid plastic for structural support, metallic material (steel wool or mesh) for heat absorption and flame inhibition, and electrical insulation for preventing short circuits. This composite approach provides comprehensive protection while optimizing weight by using each material only where needed.
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
Effectively mitigates thermal runaway by quickly extinguishing flames and releasing gases, preventing external propagation and protecting adjacent cells from thermal damage, ensuring the safety of the battery pack during incidents.
Implementation Method 1
a mass of metallic material to absorb the heat in order to extinguish the flames that can appear during such thermal runaway
Implementation Method 2
The gases under pressure that can get formed inside the pack can escape through holes made in the lids of the casing
Implementation Method 3
The metallic mass instantaneously absorbs the heat of the fumes, reduces the temperature and prevents the propagation of the flames
Data Source
AI summary
A battery pack includes a plurality of electrical energy storage cells positioned in a parallel layout in a protective casing. The protective casing has a peripheral wall and is closed at two opposite ends by a lid. Each of the lids has at least one venting hole for gases that that can form inside the protective casing, and at least one layer of metallic material, through which the gases are intended to flow, is disposed between the internal face of each of the lids and the cells.