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This study aims to measure and assess the thermal and fire hazards associated with the bulk shipment and passenger electronics of lithium-ion cells carried on airplanes. It examines various incidents involving aircraft fires caused by lithium batteries and identifies the causes of thermal runaway. The research also investigates the energetic capacity and thermodynamics of different lithium-ion cell chemistries. Experimental testing, including bomb calorimetry and gravimetric analysis, is conducted to evaluate the energy release and volatile mass loss during cell failure. The study concludes by discussing the fire hazards and potential risks posed by single lithium-ion cells.
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Measure thermal and fire hazards of lithium ion cells carried on airplanes Objective Bulk shipment (cargo) Passenger electronics
Fire erupted in a cargo plane that landed in Philadelphia on Feb. 7, 2006. A cargo plane with 81,000 lithium batteries caught fire and crashed after it left Dubai on Sept. 3, 2010. A cargo jet crashed into the East China Sea on July 28, 2011, after the crew reported a fire on board. Aircraft Fire Incidents Involving Li Batteries
Thermal Separator melts due to high temperature causing internal short circuit that liberates heat. Contents mix, react and thermally decompose. Mechanical Physical damage (puncture) Li dendrite grows to short circuit Electrical Overcharge Rapid discharge Causes of Thermal Runaway Typical bulk shipment All lead to temperature increase and acceleration of chemical decomposition
Materials: Lithium Ion Rechargeable (V) vs. Q (Coulombs) at Temperature 18650 Cells ( 44 grams each) 65 mm 18 mm Typical 18650
Charge / Discharge 4 batteries at a time individually Records charge / discharge capacity Programmable for different states of charge Methods: Cell Charging
LiMn2O4-LiNiCoO2 LiCoO2 LiNiCoAlO2 Unknown Electrical Properties of Tested Cells Maximum Capacity,Qmax (A-s) max(V) Energetic Capacity, Emax (kJ/cell) Cathode Rated Actual Rated Actual 11,700 9,400 5,400 18,000 11,200 8,300 5,000 3,600 3.6 3.7 3.7 3.7 4.1 4.1 4.1 4.0 41 31 19 13
Parr Instruments Model 1341 Plain Jacket Oxygen Bomb Calorimeter Resistance heating to force thermal runaway of LIBs Nitrogen blanket (1 Atm) to prevent oxidation of contents after failure Temperature, voltage and current logged for all tests Bomb Calorimeter (ASTM D 5865) Experimental Setup Bomb and other components for 18650 battery tests
500 1000 1500 2000 2500 3000 Baseline Corrected Temperature History In Bomb 6 SOC 100% 5 80% 4 50% Temperature Rise (C) 3 2 20% 0% 1 0 Time (seconds)
Zero Charge 50% Charged 100% Charged Li-Ion 18650 Batteries - Post Test
Gravimetric Analysis & FTIR of Volatiles • Bomb weighed before and after venting to atmosphere to determine volatile yield • FTIR analysis of volatiles shows COx, HC but misses H2 ( 30% of volaltiles)
Energy Release Histories In Bomb Calorimeter Unknown Cathode LiNiCoAlO2 60 60 Z = 1 50 0.74 50 Z = 1 0.46 40 0.59 40 Total Energy Release, ∆Uf (kJ/cell) Total Energy Release, ∆Uf (kJ/cell) 0.42 0.24 30 30 0.26 0 20 0 20 10 10 0 0 0 50 100 150 0 50 100 150 200 Time (minutes) Time (minutes) LiCoO2 LiMn2O4-LiNiCoO2 120 100 Z = 1 Z = 1 100 80 0.70 0.67 80 0.46 60 Total Energy Release, ∆Uf (kJ/cell) Total Energy Release, ∆Uf (kJ/cell) 0.43 60 0.14 40 40 0.17 20 0 20 0 0 0 0 50 100 150 0 50 100 150 200 Time (minutes) Time (minutes)
Cell Thermodynamics Total Energy of Cell Failure (in bomb) Depends on cell chemistry Free energy, E (J) = Charge*Voltage • Chemical energy of • Mixing • Reaction • Thermal decomposition …of cell components
80 60 70 50 60 40 50 30 40 20 30 10 20 0 10 0 -10 0 10 20 30 40 50 60 0 5 10 15 20 25 30 35 40 40 30 25 30 20 20 15 10 10 5 0 0 -10 -5 0 5 10 15 20 25 0 5 10 15 20 Energetics of Individual Cell Failure LiMn2O4-LiNiCoO2 LiCoO2 ∆Utotal ∆Utotal ∆Urxn ∆Urxn Energy Release at Failure (kJ/cell) LiNiCoAlO2 Unknown ∆Utotal ∆Utotal ∆Urxn ∆Urxn Electrochemical Free Energy, Q (kJ/cell)
Unknown LiNiCoAlO2 LiCoO2 LiMn2O4-LiNiCoO2 80 70 60 50 40 30 20 10 0 0 500 1000 1500 2000 2500 3000 3500 Generalized Energetics at Failure 18650 Cell Chemistry Total Energy (∆Utotal) Energy of Mixing, Reaction and Decomposition ∆Urxn 88% of Q Energy Release at Failure (kJ/cell) Electrical (Free) Energy (E) Charge, Q (mAh)
6 80 70 5 60 4 50 3 40 30 2 20 1 10 0 0 0 20 40 60 80 100 0 20 40 60 80 100 State-of-Charge is a Poor Predictor of ∆Uf, ∆mg for Different Cathode Chemistries Total Energy LiMn2O4- LiNiCoO2 LiMn2O4- LiNiCoO2 LiCoO2 LiCoO2 Total Failure Energy, ∆Uf (kJ/cell) Volatile Mass Loss, ∆mg (g/cell) LiNiCoAlO2 LiNiCoAlO2 Unknown Unknown Fractional Charge, Z = Q/Qmax (%) Fractional Charge, Z = Q/Qmax (%)
LiCoO2 LiNiCoAlO2 LiMn2O4-LiNiCoO2 Unknown 6 80 5 60 4 40 3 20 2 0 1 0 -20 -10 0 10 20 30 40 50 -10 0 10 20 30 40 50 Electrical Energy (E) is Good Predictor of ∆Uf, ∆mgFor Different Cathode Chemistries Total Failure Energy, ∆Uf (kJ/cell) Volatile Mass (g/cell) Electrical Energy, E (kJ/cell) Electrical Energy, E (kJ/cell)
Fire Calorimeter Testing of Lithium Cells Standard ASTM E 1354 Operation Special holder designed to prevent rocketing of cell at failure
20 15 10 5 0 0 20 40 60 80 100 Mass Loss of 18650 Cell in Fire Calorimeter Test LiCoO2, 2600 mAh, 3.7V Gases + Liquids + Solids (from fire calorimeter) Mass Loss (g/cell) Gases (from bomb calorimeter) State of Charge, Q/Qmax (%)
Fire Hazards of Single Li Ion 18650 Cell Discharge of Stored Electrochemical Energy (Internal Short Circuit) (40 kJ/cell) Total = 135 kJ/cell = 3 kJ/g 1/15 jet fuel Flaming Combustion of Cell Contents (75 kJ/cell) LiCoO2 Cell at 50% SOC 75 kJ/18650 cell qv = 6.62 x 10-5 m3/ cell Decomposition Reactions (20 kJ/cell) = 1 GW/m3
L(t) L(t) L(t) Model of 18650 Cargo Fire V(t) = L(t)3 Effective Length of 18650, Constant linear propagation rate, Linear Fire Growth Rate,
1200 1000 800 600 400 200 0 0 10 20 30 40 50 60 70 Model Versus Full Scale Test Data Full-Scale Test (Before) Full-Scale Test (After) Class E Main Deck Cargo Model (LiCoO218650 @ 50% SOC) Heat Release Rate (kW) Full Scale Test Data 18650 LIB at 50% SOC (from O2 consumption) H. Webster , May 2013 Time After First Ignition, minutes
Summary Total energy of anaerobic Li Ion cell failure ∆Utotal is approximately twice the stored electrochemical (free) energy, E = Q, for the 18650 cell chemistries of this study Thermal hazards of 18650 Li Ion cell failure are rapid heating (300C/s) to temperatures of 600C-1200C, which propagates failure to adjacent cells. These temperatures can be approximated using E = Q. Fire hazards of LIBs are burning, conflagration and/or explosion of the gaseous thermal decomposition products of cell failure. Although the heat of combustion of LIBs gases is less than that of typical solids and gases, LIBs release gases rapidly at failure which can result in conflagration or explosion in (cargo) compartments. State-of-charge is a poor predictor of fire hazard for different cell chemistries.