Battery Cell Grating for Thermal Runaway Particle Fragmentation
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Solution Overview
Problem
High voltage battery cells in electric vehicles face risks of thermal runaway and subsequent particle ejection during mechanical impacts or overcharging, which can lead to short circuits and damage to adjacent cells due to large particles being ejected during thermal runaway.
Innovation Solution
A grating with multiple parallel grating webs is integrated into the battery cell to fragment larger particles formed during electrode destruction, reducing the risk of short circuits by breaking them into smaller pieces as they flow through the grating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a bursting membrane is used to dissipate overpressure during thermal runaway, then the positive pressure in the battery cell is reduced, but large particles from the electrode stack are ejected causing short circuits in adjacent cells
Solution Approach 1:
A grating is introduced as an intermediary component between the electrode stack and the bursting membrane. The grating has a specific mesh structure that allows gas to pass through while blocking and fragmenting large particles. This intermediary structure resolves the contradiction by enabling pressure relief while preventing harmful particle ejection that would otherwise occur through the bursting membrane alone
Solution Approach 2:
The grating structure segments the particle flow path into multiple small openings. When particles are ejected during thermal runaway, they must pass through these segmented openings which fragment them into smaller pieces. This segmentation prevents large intact particles from reaching and causing short circuits in adjacent cells, while still allowing gas pressure to be relieved
2Speed
If the bursting membrane is opened rapidly to release pressure, then overpressure is relieved quickly, but large particles are ejected with high velocity causing damage to adjacent battery cells
Solution Approach 1:
The grating serves as a velocity-reducing intermediary that particles must pass through during rapid decompression. The multiple small openings and the structure of the grating slow down particle velocity while gas passes through more rapidly. This allows quick pressure relief while reducing particle ejection velocity to safe levels
Solution Approach 2:
The grating functions as a porous structure with specific pore sizes and distributions. This porous structure allows gas to pass through rapidly (maintaining high pressure relief speed) while the pore geometry physically limits and reduces the velocity of particles attempting to pass through, thereby decoupling the two 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
The grating effectively reduces the size of ejected particles, minimizing the risk of short circuits and damage to adjacent battery cells, thereby enhancing safety and preventing thermal runaway propagation.
Implementation Method 1
the particles from the destroyed electrode unit may strike the grating webs and, as a result, may be divided into two or more fragments
Implementation Method 2
the electrolyte can evaporate and the active materials can break down. As a result, a positive pressure is produced in a built-up manner which indeed can be reduced by opening a bursting membrane
Data Source
AI summary
Described is a battery cell (20) comprising at least one electrode unit (10), and a grating (13) having a plurality of grating webs (15) being arranged in the battery cell (20). The grating (13) is suitable to at least partly reduce the size of any particles produced when the electrode unit (10) is destroyed.