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VIRTUAL VEHICLE Research Center is funded within the COMET – Competence Centers for Excellent Technologies – programme by the Austrian Federal Ministry for Transport, Innovation and Technology (BMVIT), the Federal Ministry of Science, Research and Economy (BMWFW), the Austrian Research Promotion Agency (FFG), the province of Styria and the Styrian Business Promotion Agency (SFG). The COMET programme is administrated by FFG.
INITIATION OF THERMAL RUNAWAY WITH DIFFERENT HEATING DEVICES
Andrej GolubkovVIRTUAL VEHICLE Research CenterArial, 18
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Motivation
Experimental
Simulation
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Motivation
Experimental
Simulation
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How to start TR of the initial cell for propagation certification, my opinion
08.03.2018 / Golubkov Initiation of thermal runaway propagation 5
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How to start TR of the initial cell for propagation certification, my opinion
08.03.2018 / Golubkov Initiation of thermal runaway propagation 6
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Motivation
Experimental
Simulation
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Laboratory for thermal runaway experiments with large Li-ion cells
08.03.2018 / Golubkov Initiation of thermal runaway propagation 8
Reactor for
• cells up to 500 Wh• 30 Thermocouples• Feedthroughs for 400 A• Volume 120 l
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Ventgas analysis
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FTIR: Bruker Matrix MG01
For all ventgas-components (incl. HF) except H2
GC: Agilent microGC 3000
For CO2, CO, CH4, Hydrocarbons, H2
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Sample holder
08.03.2018 / Golubkov Initiation of thermal runaway propagation 10
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Space for the sample holder
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245
Space for sample set-up
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Sample holder for pouch cells
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Springs to simulate mechanical force inside a module.
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Tested cell before and after TR experiment
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Test results: cell temperatures
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Heating from both sides Heating from one side Heating with heater cardrige
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Test results: cell temperatures, detail
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Heating from both sides Heating from one side Heating with heater cardrige
5 sec10 sec
30 sec
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Test results: gas pressure
08.03.2018 / Golubkov Initiation of thermal runaway propagation 16
Heating from both sides Heating from one side Heating with heater cardrige
4 sec 7 sec23 sec
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Open the cell (inside fumehood!)
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Put 3 thermocouples into the middle of the electrode stack
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TR temperatures, including internal thermocouples
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TR temperatures, including internal thermocouples
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center
outerNeed to measure internal temperature to create a TR model
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Why no put heater elements into cell?
08.03.2018 / Golubkov Initiation of thermal runaway propagation 21
• Heater wire put into jelly roll.• Tried to trigger TR by heating, wire fails before TR• Opened cell again, inserted new heater wire• Triggering TR with heater wire fails again• Instead triggering TR by sample holder heating• TR at already 100°C. Probably because of internal short.
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TR of the damaged cell, already at 100°C
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Direct transition to TR
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External heating and possible internal short
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Abrupt increase of temperatureDiscontinual curvatureTransition at 110°C
Even increase of temperatureContinual curvatureTransition at 200°C
Normal TR Probably internal short at 110°C of a damaged cell
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Next
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Inser better heating wire devices into pouch cell.
Try other small heater devices, which could also fit into a battery moduleE.g: small silicon nitride ceramic heater, available in different sizes. Down to 3 x 7 mm
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Motivation
Experimental
Simulation
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Use LT-spice for thermal network simulation
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Thermal network for a 3p2s module
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Examples of simulation results
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No propagation
smaller spacer thickness
Propagation occurs
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Testing Openmodellica
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Testing Openmodellica
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No spacer between cells Spacer: 1mm mica sheet
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What influences if TR-propagation takes place
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• TR characteristics of the cell
• Starting temperature of the module
• What is initial cell (oustide vs. centre)
• Heat conduction between adjacent cells
• Other heat-capacities (mechanical structure, cooling liquid)
• Cooling power
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Proposed next steps
08.03.2018 / Golubkov Initiation of thermal runaway propagation 32
Exchange LT-spice for Openmodellica (or Dymola)
Make Library for thermal elements
• Heat conductor, PCM, heat pipe,..
• Make individual cell models of TR from experiment (e.g. use internal
thermocouples)
• Measure heat conductivity and heat capacity of a failed cell
Industry can use this tools to find solutions for prevention of TR propagation.
