The Effect of Thermal Management Material on Thermal Runaway - - PowerPoint PPT Presentation

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The Effect of Thermal Management Material on Thermal Runaway - - PowerPoint PPT Presentation

Aug 21, 2023 956 likes •1.18k views

The Effect of Thermal Management Material on Thermal Runaway Propagation Greg Wilk, Siddique Khateeb, Stephen Wilke, Greg Albright, Said Al-Hallaj R&D Engineer, AllCell Technologies http://www.allcelltech.com Compact | Lightweight | Long

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Compact | Lightweight | Long Lasting

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The Effect of Thermal Management Material on Thermal Runaway Propagation

Greg Wilk, Siddique Khateeb, Stephen Wilke, Greg Albright, Said Al-Hallaj R&D Engineer, AllCell Technologies http://www.allcelltech.com

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Compact | Lightweight | Long Lasting

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Lithium-Ion Battery Fires

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Lithium-Ion Battery Fires

  • Lithium ion battery fires serious threat
  • Hoverboards
  • Galaxy Note 7
  • Safety concern for aerospace companies
  • Dreamliner grounded due to battery fire
  • Jet propulsion laboratory prototype robot destroyed by 98 cell explosion
  • Must engineer lithium ion packs assuming one cell will short
  • Boeing with the best BMS and fusing still had a failed cell cause a

catastrophic fire

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Thermal Runaway, Cell Level

  • Thermal runaway: Cell

chemistry reacts rapidly generating heat

  • Accelerating Rate

Calorimetry

  • See what temperature

cell enters TR

  • Depends on cell and

state of charge

  • 90°C to 120°C

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100 200 300 400 500 600 700 800 500 1000 1500 Temperature (°C) Total Test Time (min)

Raw Data - Temperature vs Time ( 2.9 Ah)

0146 0153 Threshold: 100°C

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Thermal Runaway Propagation: Heat transfer

Success Criteria: Adjacent cell temperature Tc < 100°C

  • Q: Cell heat generation from TR
  • Cell energy
  • Parallel welds
  • Combustion
  • Conduction to adjacent cells
  • Pack material thermal diffusivity
  • Cladding thickness
  • Contact resistance
  • Convection to surroundings
  • Thermal diffusivity a function of

temperature in phase change materials

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Q

Tc < 100°C

𝑈

𝑑 ≈ 𝐸 =

𝑙 𝜍𝐷𝑞(𝑈)

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Research Overview

  • Evaluate what cell packaging materials

can prevent the propagation of thermal runaway in a small pack of 18650 style cells.

  • Air
  • Graphite
  • Wax
  • Graphite and Wax (PCC)
  • Evaluate the importance of battery

configuration and weld strength on thermal runaway propagation

  • Nail penetration test
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Battery Pack Materials Evaluated

  • Phase Change Composite (PCC)
  • 20 wt.% graphite
  • 80 wt.% wax
  • Wax micro-encapsulated
  • Melts at 55°C
  • ½ Latent heat of ice
  • Graphite only (90% porous)
  • Wax (100%)
  • Air

7 Li Li-io ion n Cells PCC Materia ial

Time

Temperat erature ure With h No PCC Temper erat ature e with PCC

Melti ting g Point

Temperature ure Remain ins Const stant nt Durin ing g Meltin ing

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Different Material Properties

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Air PCC Graphite Only Wax Only Air Graphite ite Only Wax Only PCC Conductivity (W/m-K) 0.024 13.77 (in-plane) 0.15 17.21 (in-plane) Density (kg/m3) 1.23 200 775 935 Specific Heat (J/kg-K) 1005 725 2384 1837 Latent Heat (J/g) N/A N/A 211 153 Diffusivity (mm2/s) 19.42 94.96 0.08 10.02

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Battery Pack Specifications

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Pack k speci ecificati ication

  • ns

Specif cificati ication

  • n

Value Config igurat uratio ion 10s4p Ene nergy gy (Wh) h) 413 Voltag age, nominal nal (V) 36.2 Mass ss (kg) 2.75 Specific cific Ene nergy gy (Wh h kg-1) 150 Dimen ension sions s (cm) 32 x 9 x 13 Casi sing ng Aluminum & plastic Cell speci ecificatio ications ns Specif cificati ication

  • n

Value Form Fact ctor 18650 Capacit acity, nominal inal (Ah) 2.85 Voltag age, nominal nal (V) 3.62 Specif cific ic Energy gy (Wh kg-1) 224 Ene nergy gy Densi sity ty (Wh h L-1) 603 Chemis mistry ry Graphite anode, NCA cathode

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Pack Build Procedure

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6 welds on trigger cell (normally 4) Hole drilled in casing for nail penetration

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Air Pack TRP Video

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  • https://youtu.be/vmUpbou8VtA
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Air Pack: Thermal Runaway Propagation

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1 2 4 3 5 Trigger String Neighbor String

100 200 300 400 500 600 700 100 200 300 400 500 600 700

Temperature (C) Time (s)

T1 T2 T3 T4 T5

Threshold

1 2 3 4 100 200 300 400 500 600 700

Voltage (V) Time (s)

Trigger Neighbor

  • TRP occurred slowly due to air low

thermal conductivity and low ability to store heat

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Graphite Only: Thermal Runaway Propagation

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1 2 3 4 50 100 150 200 250 300

Voltage (V) Time (s)

Trigger Neighbor 200 400 600 800 1000 1200 50 100 150 200 250 300

Temperature (C) Time (s)

T/C-1 °C T/C-3 °C T/C-4 °C T/C-5 °C

1 4 3 5 Trigger String Neighbor String Threshold

  • TRP occurred quickly due to high

thermal conductivity and low ability to store heat

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Wax Only: Thermal Runaway Propagation

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1 4 5 Trigger String Neighbor String 2

100 200 300 400 500 600 700 50 100 150 200 250 300 350 400 450 500

Temperature (C) Time (s)

T1 T2 T4 T5

  • 2
  • 1

1 2 3 4 5 50 100 150 200 250 300 350 400 450 500

Voltage (V) Time (s)

Trigger Neighbor

Threshold

  • TRP occurred quickly due to liquid

wax flow and wax combustion

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50 100 150 200 250 50 100 150 200 250 300 350 400

Temperature (C) Time (s)

T1 T2 T3 T4 T5

Phase Change Composite (PCC): Avoided Thermal Runaway Propagation

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1 2 4 3 5 Trigger String Neighbor String

1 2 3 4 50 100 150 200 250 300 350 400

Voltage (V) Time (s)

Trigger Neighbor

Threshold

  • TRP was prevented due to phase

change absorbing thermal runaway energy

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Comparison Between Packs

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Pack k Material ial Thermal Runaway Propagat gation ion? Air Fail Graphite Fail Wax Fail PCC Pass

100 200 300 400 500 600 700 50 100 150 200 250 300 Temperature (C) Time (s) Trigger Cell Neighbor Cell

Peak Temperature

Time to neighbor cell peak temp.

100 150 200 250 300 350 50 100 150 200 250 300 350 400

Neighbor Cell Peak Temperature (C) Time to Neighbor Cell Peak Temperature (s)

Air Graphite Wax PCC

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Autopsy

The herm rmal al Run unaway ay Prop

  • pagati

ation

  • n

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No

  • The

hermal mal Run unaway ay Prop

  • pagatio

tion

*Pack was sprayed with water after second cell propagated in packs that propagated

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Nickel separation during cell venting

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Nickel Cladding can separate from venting cell isolating electrical energy available for thermal runway propagation Not 100% reliable separation. Cells can vent outside of side casing

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Ongoing Research with PCC

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Cell Ene nergy Pack k Con

  • nfigur

urati ation

  • n

The herm rmal al Run unaway ay Prop

  • pagati

ation

  • n

2.9 Ah 10s4p Pass 3.2 Ah 10s4p Pass 3.5 Ah 10s4p Fail 3.5 Ah 10s0p Pass

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Conclusions and Future Work

  • PCC (graphite and wax) reliably prevented TRP

in 2.9 Ah, 10s4p packs

  • Packs need to be engineered for TRP on a case

by case basis

  • Cell energy (2.9, 3.2, 3.5 Ah…)
  • Material thermal properties
  • Parallel configuration and cladding separation
  • Future tests will investigate different cell

energies and graphite densities for AllCell Battery Products: http://www.allcelltech.com/

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Contact Information

  • http://www.allcelltech.com/
  • Greg Wilk, R&D Engineer, gwilk@allcelltech.com, 773-922-1155 (x244)
  • Siddique Khateeb, Head of R&D, Skhateeb@allcelltech.com
  • Greg Albright, VP of Business Development, galbright@allcelltech.com,

773-922-1155 (x211)

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