Warehouse Protection of Cartoned Lithium Ion Batteries

Presented by:

R. Tom Long, Exponent Inc.

Benjamin Ditch, FM Global

2017 NFPA Conference & Expo

22

Li-Ion Battery Hazards and

Characterization

R.T. Long

3

Project Timeline

• Phase 1, 2010 - Hazard Assessment

• Phase 2, 2013 – Survey & Reduced

Commodity Full Scale Tests

• Phase 3, 2016 – Full Scale Suppression

Tests

• All full scale testing conducted by FM Global

• Funded by PIRG through FPRF

20 Ah

Phase 3, 2016

Polymer

2.6 Ah

Phase 2, 2012

Cylindrical

Polymer

Power tool

packs

Reduced-

commodity

evaluation

Sprinklered

fire test

20 Ah

Phase 3, 2015

Polymer

4

Battery Descriptions

• Battery characterization

– 2.6 Ah cylindrical (18650)

– 2.6 Ah polymer pouch

– 26 Ah power tool packs

– 20 Ah polymer pouch

• Aspects of batteries analyzed

– Battery: Chemistry, electrolyte mass, voltage, SOC, etc.

– Packaging: cartons, dividers, etc.

– Significant effort to understand “what” was being tested

Phase 2

Phase 3

5

What is a Li-ion Cell?

6

What is a Li-ion Battery?

• A Li-ion battery pack contains

– An enclosure

– One or more cells

– Protection electronics

7

Why is Li-Ion different?

• Unique hazards for Li-ion technology

– Fire can initiate within the battery

– Flammable Electrolyte

• Failure mode dependent on battery type

– Venting mechanism

– Chemistry

– State-of-charge

• Packaging or system components

– Other contributions to fire development

8

Cell Thermal Runaway

1. Cell internal temperature increases

2. Cell internal pressure increases

3. Cell undergoes venting

4. Cell vent gases may ignite

5. Cell contents may be ejected

6. Cell thermal runaway may propagate to adjacent cells

Cell

windings

Open center of

cell

Blockage in

center of cell

Pressure

buildup at base

9

Thermal Runaway- How do you get there?

• Thermal Abuse: Exceed the thermal stability limits: external heating

• Mechanical Abuse: Can cause shorting between cell electrodes, leading to localized heating that propagates and initiates thermal runaway;

• Electrical Abuse: Overcharge, External Short Circuit, Over-discharge

• Internal Cell Faults: For commercial Li-ion packs with mature protection electronics packages, the majority of thermal runaway failures are caused by internal cell faults

10

Battery Life Cycle Hazards

• Key Finding: Warehouse setting was frequent throughout lifecycle of batteries

• Warehouse setting

– Failure modes:

• Mechanical abuse – cells being crushed, punctured, dropped

• Electrical abuse – short circuiting improperly packaged cells/ packs

• Thermal abuse – external fire

• Internal fault – unlikely unless cells being charged

– Mitigation:

• Cells/packs usually stored at reduced states of charge (50% SOC or less)

• Cells/packs can be contained in packaging to prevent mechanical and external short circuit damage

• Fire suppression strategies

11

Knowledge Gaps

• Gap 1: Leaked Electrolyte & Vent Gas Composition

• Gap 2: Sprinkler Protection criteria for Li-ion Cells

• Gap 3: Effectiveness of Various Suppressants

• Gap 4: Post – Fire Cleanup Issues

12

Gap 2: Sprinkler Protection

• NFPA 13 - No fire protection suppression strategy for Li-ion cells

• Infrastructure for most occupancies allows for water based protection

• Is water appropriate extinguishing medium for Li-ion batteries?

• NFPA 13 Table A.5.6.3:

– Dry cells (non-Li or similar exotic metals) in cartons: Class I (e.g. alkaline)

– Dry cells (non-Li or similar exotic metals) blister packed in cartons: Class II (e.g. alkaline)

– Automobile batteries – filled: Class I (e.g. lead acid water-based electrolyte);

– Truck or larger batteries, empty or filled Group A Plastics (e.g. lead acid water-based electrolyte);

• Li-ion chemistries are not included

• Full Scale testing appropriate

13

For full scale tests - need to define

• Commodities– Cell chemistry

– Cell size / form factor

– Cell SOC

– Packaging configuration

• Storage geometries and arrangements

• Full scale tests of every cell type / configuration is not practical– Select “most typical types”

• Purchasing commodities for testing is expensive

14

Survey

• 2012

• Responders typically engaged in:

– Manufacturing

– Research

– Recycling

– Almost all responders stored batteries, cells, or devices with batteries/cells.

15

Survey Responses Summary

• Battery Types at the Surveyed Facilities: Cylindrical cells were the most common form factor. Small format was the most common size.

• Tasks Carried Out at Facilities Surveyed: Most of the responding facilities were engaged in the storage of cells, battery packs or devices.

• Packaging of Received Batteries: Cells typically arrive in cardboard boxes. These boxes may be on wooden pallets and/or encapsulated.

• Rack storage type: Movable racks were more common than fixed racks, and shelves were more likely to be perforated than solid.

16

Flammability Characterization

• Full scale tests

• Limited quantities of batteries/cells

• Rack storage arrangement

• Free burn/external ignition source

• Hard and soft case batteries with similar energy densities

• Battery packs with appreciable plastics

• Due to costs, tests required an unique approach to full scale tests: FM Global – reduced commodity testing

17

Battery Acquisition and Characterization:

Phase 2 Reduced Commodity Tests (RCT)

Parameter Power tool packs

18650

18650 cells Li-Polymer cells

Nominal voltage 3.7 V 3.7 V 3.7 V

Nominal capacity 1300 mAh 2600 mAh 2700 mAh

Mass of Cell 42.9 g 47.2 g 50.0 g

Approximate mass of

electrolyte solvent

3.3 g 2.6 g 4.0 g

Cell chemistry Lithium Nickel

Manganese Cobalt

Oxide (NMC)

Lithium Cobalt

Oxide (LCO)

Lithium Cobalt Oxide

(LCO)

Approx. state of charge (SOC)

as received

50% 40% 60%

18

Power Tool Packs – Overview (RCT)

• 18 V, 48 Wh Lithium-Ion power tool packs Ryobi P104

• ~(5 ½” long) x (3 ¼” wide) x (4 ¼” tall)

• Blister packs plus casing presented an appreciable amount of plastics

Onboard “fuel gauge” indicator lights orange, indicating mid state of charge

19

Power Tool Packs – Construction (RCT)Hard injection-molded plastic shell

Rubber feet

Hard plastic frame

Soft foam padding

Protection printed circuit board (PCB) / Battery Management Unit (BMU)

Flexible rubber padding

20

Power Tool Packs (RCT) Characterization

• High-Power Lithium-Ion Cells• Form Factor: 18650 Hard case cylindrical cells x 10, 5 series 2

parallel configuration• Dimensions: 18 mm x 65.0 mm• Cell enclosure: steel can with shrink wrap• Chemistry: NMC (Lithium Nickel Manganese Cobalt Oxide)• Nominal voltage: 3.7 V

• 5 series elements @ 3.7 V nominal = 18.5 V nominal pack voltage

• Nominal capacity: 1300 mAh• 2 parallel elements @ 1300 mAh per cell = 2600 mAh capacity

• 18.5 V x 2.6 Ah = 48.1 Wh nominal pack energy• Approximate assembled weight: 42.9 g• Approximate mass of electrolyte solvent: 3.3 g

(+) side (with vent port) (-) side (no vent port)

Positive terminal and vent port

21

Power Tool Packs – SOC (RCT)

• Two battery packs were measured for voltage and capacity

– Both battery packs were 18.60 V (corresponding to 3.72 V per series element)

– Battery packs are close to the nominal pack voltage of 18.5 V (or nominal cell voltage of 3.7 V)

– A battery pack at the nominal voltage usually indicates it is near the halfway point of charge

– A fully charged pack would be 21 V (4.2 V x 5 series elements)

• State of Charge (SOC) was measured on one cell from each of two battery packs (S/N listed above) using a standard C/5 rate (0.26 A) constant current discharge until 2.5V was reached

– cells were determined to be close to 50% SOC

V of NFPA-sanyo-18650.015

V of NFPA-sanyo-18650.008

Capacity/mAh

6005004003002001000

Vol

tage

/V

4.2

4.1

4

3.9

3.8

3.7

3.6

3.5

3.4

3.3

3.2

3.1

3

2.9

2.8

2.7

2.6

2.5

Discharge CapacityPacksCS12233D430739 – 667 mAh (50% SOC)CS12271N430014 – 652 mAh (49% SOC)Initial voltage 3.72 V

22

Power Tool Packs -Cell Disassembly (RCT)

• Electrodes are in a jelly roll configuration, typical of 18650 cells – Sanyo 18650

• One cell was disassembled and the positive electrode was subjected to energy dispersive X-ray spectroscopy (EDS) for cell chemistry

• Cell chemistry is consistent with NMC (lithium nickel manganese cobalt oxide) chemistry, i.e. Li(NixMnyCoz)O2 where x, y, and z can vary depending on manufacturer’s formula

Negative electrode (on Cu foil)

Positive electrode (on Al foil)

Separator

Separator

Mn

Co

Ni

Positive cell tab

EDS Spectrum

O

Steel can

23

18650 Cells – Characterization (RCT)

• 18650 Lithium-Ion Cells• Form Factor: Hard case cylindrical cell

(18 mm diameter x 65.0 mm)• Cell enclosure: steel can with shrink wrap• Chemistry: LCO (Lithium cobalt oxide)• Nominal voltage: 3.7 V• Nominal capacity: 2600 mAh • Approximate assembled weight: 47.2 g• Approximate mass of electrolyte solvent:

2.6 gJelly roll in cell can

24

2.5

2.7

2.9

3.1

3.3

3.5

3.7

3.9

4.1

4.3

0 0.2 0.4 0.6 0.8 1 1.2

Volta

ge (V

)

Capacity (Ah)

18650 Channel 8

18650 Channel 15

18650 Cells – SOC (RCT)

• Two cells were measured for voltage and capacity

– Both cells were 3.74 V, close to the nominal cell voltage of 3.7 V

– A battery pack at the nominal voltage usually indicates it is near the halfway point of charge

– A fully charged cell would be 4.2 V

• State of Charge (SOC) was measured on two cells using a standard C/5 rate (0.52 A) constant current discharge until 3.0 V wasreached

Discharge Capacity Cell capacities:1.05 Ah (40% SOC)1.05 Ah (40% SOC)

Initial voltage 3.74 V

25

18650 Cells – Cell Disassembly (RCT)

• Electrodes are in a jelly roll configuration, typical of 18650 cells

• One 18650C was disassembled and the positive electrode was subjected to energy dispersive X-ray spectroscopy (EDS) to assess cell chemistry

• Cell chemistry is consistent with LCO (lithium cobalt oxide) chemistry, i.e. LiCoO2

Steel can

Negative electrode (on Cu foil)

Positive electrode (on Al foil)

Separator

Separator

O

CoEDS Spectrum

26

Li-Polymer Cells – Characterization (RCT)

• Lithium-Polymer Cells• Cell enclosure is aluminum foil coated with polymer, and

is designed to be electrically neutral and insulated• Form Factor: Li-polymer (soft pack) cell • Dimensions: 6 mm thick x 41 mm x 99 mm• Cell enclosure: aluminum foil with polymer coating• Electrode configuration: jelly roll (as opposed to stacked)• Chemistry: LCO (Lithium cobalt oxide)• Nominal voltage: 3.7 V• Nominal capacity: 2700 mAh • Approximate assembled weight: 50.0 g• Approximate mass of electrolyte solvent: 4.0 g

Coated aluminum pouch

Cell windings (“Jelly roll”)

+ tab

– tab

27

2.5

2.7

2.9

3.1

3.3

3.5

3.7

3.9

4.1

4.3

0 0.5 1 1.5 2

Volta

ge (V

)

Capacity (Ah)

Pouch 9I19

Pouch 9H27_1

Li-Polymer Cells – SOC (RCT)

• Two cells were measured for voltage and capacity

– Both cells were 3.84 V

– Battery packs are close to the nominal cell voltage of 3.7 V

– A battery pack at the nominal voltage usually indicates it is near the halfway point of charge

– A fully charged cell would be 4.2 V

• SOC was measured on two cells using a standard C/5 rate (0.54 A) constant current discharge until 3.0 V was reached

Discharge CapacityCell markings:9H27 – 1.62 Ah (60% SOC)9I19 – 1.66 Ah (61% SOC)

Initial voltage 3.84 V

28

Li-Polymer Cells – Cell Disassembly (RCT)

• Electrodes are in a jelly roll configuration, as opposed to stacked electrode design

• One Li polymer cell was disassembled and the positive electrode was subjected to energy dispersive X-ray spectroscopy (EDS) to assess cell chemistry

• Cell chemistry is consistent with LCO (lithium cobalt oxide) chemistry, i.e. LiCoO2

AlPouch

Negative electrode (on Cu foil)

Positive electrode (on Al foil)

Separator

Separator

O

CoEDS Spectrum

29

Suppression Test: Battery Cell Description

Lithium-Ion Pouch Cell

• Dimension: 9×6×0.3 in.

(230×150×8 mm)

• Weight: 1.1 lb (0.5 kg)

• Capacity: 20 Ah

• Voltage: 3.3 volts

30

Suppression Test: Electrical Characterization

• Stacked Electrode Design

• Cell Chemistry: Lithium Iron

Phosphate (LiFePO4)

• As-Received SOC: 49.4%

• Electrolyte Mass: 0.083 lb

(34 g)

31

Suppression Test: Package Description

17”

6.5”

13.5”

• Cardboard box: 17×13.5 ×6.5 in.

(430×340×170 mm)

• Total weight: 27 lb. [including cells]

(12.2 kg)

• Contents:

• 20 battery cells

• White polystyrene crates

• Polyethylene bubble wraps

32

Suppression Test: Battery Package Mass

SummaryContent per One

Package

Weight

20 Battery (including

Electrolyte)

21.7 lb

(80.5%)

10 White Battery Crates 3.9 lb

(14.3%)

Cardboard 1.4 lb

(5.0%)

Parking Material 0.04 lb

(0.1%)

Electrolyte 1.7 lb

(6.2%)

Total Weight 27.0 lb

Cardboard Box, 5.0%

Packing Material (Bubble Wrap), 0.1%

Ten (10) White Battery Crates,

14.3%

Twenty (20) Battery Cells

including Electrolyte,

80.5%

FM Global

[ Public ]

EXPERIMENTAL EVALUATION

Benjamin Ditch

FM Global

[ Public ]

Scale

FM Global Research Campus

FM Global

[ Public ]

REDUCED-COMMODITY TEST

Task 1

FM Global

[ Public ]

How to Evaluate Li-ion Batteries

Commodity classification not feasible

– Expensive and difficult to acquire

Reduced-commodity approach

– Limit commodity to ≥ one pallet load per test

– Freeburn (no water)

FM Global

[ Public ]

Reduced-Commodity Test: Design

Storage height: 15 ft (4.6 m)

Protection: none

– Freeburn

Commodity:

– 4 full pallet loads

– 4,480 batteries

Ignition

– Propane, 45 kW

5 ft

1.1

ft

Ring burner

Cartoned Li-ion Batteries

Ignition flue

Non-Combustible Non-Combustible

FM Global

[ Public ]

Reduced-Commodity Approach

Characterize fire development up to theoretical

sprinkler operation

– Test conducted under a Fire Products Collector

– Standard commodities and Li-ion batteries

Compare predicted sprinkler operation time versus

time of battery involvement

FM Global

[ Public ]

Fire Hazard Comparison

Time

He

at R

ele

ase

Rate

Class 2

CUP

Sprinkler operation prediction

(Fire size and growth rate)

FM Global

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Reduced-Commodity Test

30 s 60 s 120 s90 s

20 Ah

FM Global

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FM Global

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Hazard Comparison

FM Global

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Hazard Comparison

FM Global

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Hazard Comparison

20 Ah

FM Global

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Hazard Comparison

FM Global

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QR Sprinkler, 10 ft (3 m) Clearance

Sprinkler: RTI = 50 ft1/2s1/2, 165oF

: RTI =(28 m1/2s1/2), (74oC)

CommodityOperation

Time (s)

Qbe

(kW)

Fire Growth

Rate (kW/s)

Li-ion, 20 Ah

Prismatic Pouch 37 335 33

Li-ion,

small-format43 270 20

Standard

Commodities50 220 16

FM Global

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Comparison to Previous Testing

Similar fire development

– Initial growth dominated by cartons

– Fire size and growth rate similar at sprinkler operation

Time of significant battery Involvement

– Small-format: 300 s

– Large-format: 90 - 180 s

Large-format higher hazard than small-format

FM Global

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Potential Application of Results

Sprinkler protection option established

– Applied to all cells with a hazard ≤ cell used in sprinklered test

– Cell hazard evaluated in reduced-commodity test

Reduced-commodity test Large-scale test

Hazard

comparison

Protection

guidance

FM Global

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LARGE-SCALE TEST

Task 2

FM Global

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Large-Scale Test: Design

Storage height: 15 ft (4.6 m)

Ceiling height: 40 ft (12.2 m)

Sprinkler: K22.4 gpm/psi1/2 (320 lpm/bar1/2)

– Response: quick-response, 165oF (74oC)

– Density: 1.3 gpm/ft1/2 (53 mm/min)

– Spacing: 10 × 10 ft (3 x 3 m)

– Ignition: Offset, under-1 sprinkler

Commodity: 24 pallet loads (~27k batteries)

20 Ah

FM Global

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Existing vs. Typical

CU

PC

UP

CU

PC

UP

CU

PC

UP

CU

PC

UP

CU

PC

UP

CU

PC

UP

Cla

ss 2

Cla

ss 2

Cla

ss 2

Cla

ss 2

Cla

ss 2

Cla

ss 2

Cla

ss 2

Cla

ss 2

FM Global

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Existing vs. Typical

CU

PC

UP

CU

PC

UP

CU

PC

UP

CU

PC

UP

CU

PC

UP

CU

PC

UP

Cla

ss 2

Cla

ss 2

Cla

ss 2

Cla

ss 2

Cla

ss 2

Cla

ss 2

Cla

ss 2

Cla

ss 2

Smaller main array

– Reduced damage area

– Minimize target jump

CUP target commodity

– No fire within carton

– Requires early

extinguishment

Increased protection

FM Global

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Warehouse Storage – Success!

One sprinkler provided

effective protection

20 Ah

FM Global

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FM Global

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SUPPLEMENTAL EVALUATIONS

Task 3

FM Global

[ Public ]

Battery-to-Battery Spread

How does thermal run away spread from battery to battery?

1) Combustion of chemical energy– Battery rupture releases flammable electrolyte

– Burning electrolyte produces heat

2) Release of electrochemical energy– Electrical energy is converted to heat

– Heat transferred to adjacent batteries

Results in Fire

Results in Heat

FM Global

[ Public ]

Combustion of Chemical Energy

How much air is needed?

Electrolyte

– Air-to-fuel ratio: 7:1

– Mass per battery: 34 g

Not enough air to burn ONE battery

Fire must burn outside carton

Required AirPer Battery

Available AirPer Carton

0.2 m3 0.01 m3

7 ft3 0.35 ft3

20 Ah

FM Global

[ Public ]

Electrochemical Heat

• Film heaters: 650oF

• Battery at middle level

• Battery rupture @ 5 min

• 2 hour test duration

• Three batteries ruptured

Propagation did not occur

FM Global

[ Public ]

0.3 gpm/ft2

(12 mm/min)

What if batteries do become involved?

Pilot flame

Suppression tests

Internal ignition

Pilot flame outside carton

Water Application Apparatus

– Water applied when batteries are

involved in fire

Allows for water application at a

later stage of battery involvement

than large-scale test Front View

FM Global

[ Public ]

Flue Ignition Scenario

Pilot Ignition

Flame spread

Start of water application Suppression

Final

• Required external pilot ignition

• Fire extinguished

– Water application delayed 168 s

• 70% of batteries damaged

• Battery rupture after extinguishment

32:00

38:00

41:10 55:27

20 Ah

FM Global

[ Public ]

SUMMARY AND PROTECTION

RECOMMENDATIONS

FM Global

[ Public ]

Summary of Protection Guidance

Guidance to be included in FM Global Data Sheets

Sprinkler protection applicable to all tested

batteries, e.g.

Overall protection guidance needs to consider

additional hazards, such as battery projectiles

2.6 Ah: 20 Ah:

FM Global

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Application of Warehouse Storage Test

FM Global

[ Public ]

Application of Warehouse Storage Test

• Protection guidance confirmed

with a large-scale fire test

• Adequacy for other batteries

evaluated with small-scale to

intermediate-scale tests

FM Global

[ Public ]

Application of Warehouse Storage Test

• Protection guidance confirmed

with a large-scale fire test

• Adequacy for other batteries

evaluated with small-scale to

intermediate-scale tests

Application

• Warehouse≤ 15 ft storage

≤ 40 ft ceilings

• Sprinkler Protection– K22.4 gpm/psi1/2

– QR, 165oF

– 12 @ 35 psi

FM Global

[ Public ]

In-Process Storage

Storage up to 5 ft high

– Protect as Hazard Category 3 (HC-3) per FM Global Data

Sheet 3-26

– Recommend including 10 ft (3 m) space separation

– Applies to all Li-ion batteries tested

Cartoned power tool packs up to 15 ft (4.6 m)

– For ceilings ≤ 30 ft (9.1 m), protect as cartoned

unexpanded plastic (CUP) per FM Global Data Sheet 8-9

FM Global

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Acknowledgements

Property Insurance Research Group

Fire Protection Research Foundation

R. T. Long Jr., J. A. Sutula, M. J. Kahn, "Lithium Ion Batteries Hazard and Use Assessment Phase IIB - Flammability Characterization of

Li-ion Batteries for Storage Protection,” Fire Protection Research Foundation, 2013

B. Ditch and J. de Vries, “Flammability Characterization of Li-ion Batteries in Bulk Storage,” FM Global Technical Report, 2013

C. Mikolajczak, M. Kahn, K. White, R. T. Long Jr., "Lithium-Ion Batteries Hazard and Use Assessment," Fire Protection Research Foundation, June, 2011

Property Insurance Research Group

B. Ditch, “Development of Protection Recommendations for Li-ion Battery Bulk Storage: Sprinklered Fire Test,” FM Global Technical Report, 2016

FM Global

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More Data at…

www.nfpa.org/foundation

www.youtube.com

www.fmglobal.com/researchreports

Search: lithium ion,

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2017 NFPA Conference & Expo