Battery Cell Venting Layout to Block Thermal Propagation
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Solution Overview
Problem
Thermal runaway in battery cells of electric vehicles can lead to a chain reaction of thermal propagation among neighboring cells, posing a significant safety risk of fire or explosion.
Innovation Solution
A battery system design with aligned cell vents and degassing openings, featuring a support plate with recesses that fail at predetermined conditions to prevent thermal propagation, providing a protective shield and compensation volume for displaced material and gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a cell vent is provided in the battery cell to release pressure during thermal runaway, then the risk of fire or explosion in the battery cell is reduced, but thermal propagation to neighboring cells may occur through the base plate
Solution Approach 1:
A support plate with recesses is introduced as an intermediary element between the battery cells and the base plate. The recesses capture hot gas and material ejected from cell vents, preventing direct contact with the base plate and neighboring cells. This mediator structure effectively blocks thermal propagation while maintaining the pressure relief function of cell vents.
Solution Approach 2:
The base plate is segmented into multiple recesses, each aligned with a corresponding cell vent. This segmentation creates isolated containment zones for thermal runaway events, preventing the spread of heat and material to adjacent cells. Each recess acts as an independent barrier, dividing the potential thermal propagation path.
2Strength
If the base plate is made robust to provide structural support, then mechanical strength is improved, but thermal propagation through the base plate becomes more likely
Solution Approach 1:
The support plate exhibits local quality variations: it has recesses with reduced material thickness directly beneath each cell vent to capture thermal runaway ejecta, while maintaining sufficient overall structural strength for mechanical support. This localized modification allows the plate to provide both structural integrity and thermal protection.
Solution Approach 2:
The recesses in the support plate are pre-configured to capture and cushion the hot gas and material that will be ejected during thermal runaway. This beforehand cushioning prevents the direct impact of thermal runaway products on the base plate and neighboring cells, mitigating thermal propagation before it can occur.
3Ease of operation
If degassing openings are made large to ensure complete penetration and effective venting, then gas escape is improved, but the risk of blockage by displaced material increases
Solution Approach 1:
The recesses, which initially appear to be potential blockage zones, are actually converted into beneficial containment chambers. They capture hot gas and material that would otherwise block the degassing openings or damage the base plate. The recesses transform the potential harm of material displacement into a protective function by providing a designated space for these 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
Prevents thermal propagation to neighboring cells by acting as a protective shield and ensuring immediate pressure reduction, reducing the risk of blockage and exposure to assembly forces on cell vents.
Implementation Method 1
internal local overheating in a battery cell, e.g. due to a short circuit in the battery cell caused by an internal cell defect, can lead to thermal runaway of the battery cell
Implementation Method 2
the support plate is designed in the region of the recesses such as to fail when a predetermined boundary condition is exceeded and thus to open the degassing openings
Data Source
AI summary
A battery system with multiple battery cells and a base plate supporting the battery cells. The battery cells each have a cell housing with a cell vent which is designed to open when a predetermined limit pressure is exceeded. The base plate has a number of degassing openings corresponding to the number of battery cells, which, when viewed in the normal direction of the base plate, completely penetrate the base plate. The degassing openings and the battery cells are arranged relative to one another such that the cell vent of each battery cell is positioned opposite one of the degassing openings. A support plate is arranged between the base plate and the battery cells, which support plate has recesses arranged corresponding to the degassing openings and extending into the degassing openings as viewed in the normal direction N.