Lithium-Ion Battery Storage and Use Hazards R. Thomas Long, P.E. - - PowerPoint PPT Presentation

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Lithium-Ion Battery Storage and Use Hazards R. Thomas Long, P.E. - - PowerPoint PPT Presentation

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1 Lithium-Ion Battery Storage and Use Hazards R. Thomas Long, P.E. Mike Kahn, Ph.D. Celina Mikolajczak, P.E. February 28, 2013 SUPDET 2013 Orlando, FL 1100034.000 C0T0 0213 RTL1 2 Acknowledgements The authors would like to thank:

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Lithium-Ion Battery Storage and Use Hazards

  • R. Thomas Long, P.E.

Mike Kahn, Ph.D. Celina Mikolajczak, P.E. February 28, 2013 SUPDET 2013 Orlando, FL

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Acknowledgements

  • The authors would like to thank:
  • The FPRF and the project sponsors for giving Exponent the
  • pportunity to complete this work
  • The project Technical Panel for their many comments and

suggestions

  • The Property Insurance Research Group (PIRG)
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Today’s Topics

  • Project History
  • Brief Technology Review
  • Brief Failure Incidents and Modes
  • Brief Battery Life Cycle / Applications Hazard Assessment
  • Survey Results
  • General Research Approach
  • Battery Acquisition
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Introduction

  • Phase 1: Lithium Ion Hazard and Use Assessment
  • http://www.nfpa.org/assets/files/PDF/Research/RFLithiumIonBatteriesHazard.pdf
  • Phase 2:
  • A: Survey
  • B1: Test Planning and battery/cell

acquisition/characterization

  • B2: Full scale testing (FM global)
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What Does Li-Ion Mean?

  • Li-ion refers to a family of battery chemistries
  • Negative (anode) and positive (cathode) electrode materials

serve as hosts for lithium ions:

  • Ions intercalate into the electrode materials
  • No free lithium metal in a Li-ion cell
  • Rechargeable
  • No “standard” Li-ion cell
  • Electrolyte = flammable
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What is a Li-ion Cell?

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What is a Li-ion Battery?

  • A Li-ion battery pack contains
  • An enclosure
  • One or more cells
  • Protection electronics
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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

  • f cell

Blockage in center of cell Pressure buildup at base

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Thermal Runaway- How do you get there

  • Thermal Abuse: The most direct way to exceed the thermal stability

limits of a Li-ion cell is to subject it to external heating

  • Mechanical Abuse: Mechanical abuse of cells can cause shorting

between cell electrodes, leading to localized cell heating that propagates to the entire cell and initiates thermal runaway;

  • Electrical Abuse: Overcharge, External Short Circuit, Over-discharge
  • Internal Cell Faults: For commercial Li-ion battery packs with mature

protection electronics packages, the majority of thermal runaway failures in the field are caused by internal cell faults

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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 and packs can be contained in packaging to prevent mechanical and

external short circuit damage

  • Fire suppression strategies
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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
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Gap 2: Sprinkler Protection

2.1: At present there is no fire protection suppression strategy for Li-ion cells 2.1a: Bulk packaged Li-ion cells 2.1b: Large format Li-ion cells 2.1c: Li-ion cells contained in or packed with equipment

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Gap 2: Overview

  • Current infrastructure in most occupancies includes the

ability to provide water based fire protection systems

  • Currently not known if water is the most appropriate

extinguishing medium for Li-ion batteries

  • NFPA 13 does not provide a specific recommendation for

the protection of or fire protection strategies for Li-ion cells

  • r complete batteries
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Gap 2: Sprinkler Protection for Li-Ion NFPA 13 ‘battery” Commodity Classifications

  • NFPA 13 provides a list of commodity classes for various

commodities in Table A.5.6.3.

  • Dry cells (non-lithium or similar exotic metals) packaged in cartons:

Class I (for example alkaline cells);

  • Dry cells (non-lithium or similar exotic metals) blister packed in cartons:

Class II (for example alkaline cells);

  • Automobile batteries – filled: Class I (typically lead acid batteries with

water-based electrolyte);

  • Truck or larger batteries, empty or filled Group A Plastics (typically lead

acid batteries with water-based electrolyte);

  • Li-ion chemistries are not included
  • Full Scale testing appropriate
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Gap 2: Sprinkler Protection for Li-Ion

  • For full scale tests needed to define
  • Commodities
  • Cell chemistry
  • Cell size / form factor
  • Cell SOC
  • Packaging configuration
  • Storage geometries and arrangments
  • Full scale tests of every cell type / configuration is not practical
  • Select a “most typical case”
  • Purchasing commodities for testing is expensive
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Survey

  • Conducted in 2012
  • Responders were typically engaged in:
  • Manufacturing
  • Research
  • Recycling
  • Almost all responders stored batteries, cells, or devices with

batteries/cells.

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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.

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Battery Aquissition

Parameter Power tool 18650 18650 Li-Polymer 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%

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Ryobi P104 Power Tool Packs – Overview

  • 18 V, 48 Wh Lithium-Ion power tool packs selected over lower voltage, lower capacity packs in

an effort to maximize the ratio of lithium-ion battery cells to packaging materials

  • The battery packs measure approximately (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

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Ryobi P104 Power Tool Packs – Construction

  • Battery pack materials include a protection PCB, spot-welded nickel interconnects, hard plastic

structural elements, flexible rubber elements (rubber feet and internal flexible rubber padding), and soft foam padding for vibration resistance

Hard injection-molded plastic shell Rubber feet Bottom View Hard plastic frame Soft foam padding

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

Flexible rubber padding

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Ryobi P104 Power Tool Packs – Characterization

  • The unit is constructed using 10 18650 cells in a 5 series, 2 parallel configuration
  • 5 series elements @ 3.7 V nominal = 18.5 V nominal pack voltage
  • 2 parallel elements @ 1300 mAh per cell = 2600 mAh capacity
  • 18.5 V x 2.6 Ah = 48.1 Wh nominal pack energy (Packaging indicates “18 V” / “48 Wh” for simplicity)
  • The cells are arranged in alternating fashion, thus vent ports (on the positive terminal side) face both sides of the

battery pack. Cell venting would occur on both sides of the pack during overpressure events.

  • High-Power Lithium-Ion Cells
  • Form Factor: 18650 Hard case cylindrical cells
  • 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
  • Nominal capacity: 1300 mAh
  • 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

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Power Tool Packs – SOC

  • 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

  • Both cells were determined to be close to 50% SOC

Capacity/mAh 600 500 400 300 200 100 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 Capacity Pack S/ CS12233D430739 – 667 mAh (50% SOC) CS12271N430014 – 652 mAh (49% SOC) Initial voltage 3.72 V

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Ryobi Packs – Sanyo 18650 Cell Disassembly

  • Electrodes are in a jelly roll configuration,

typical of 18650 cells

  • One 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 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

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18650 Cells – Characterization

  • 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 g

Jelly roll in cell can

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18650 Cells – State of charge (SOC)

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

Initial voltage 3.74 V

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18650 Cells – Cell Disassembly

  • 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 Co EDS Spectrum

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Li-Polymer Cells – Characterization

  • Lithium-Polymer Cells
  • 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”)

  • Cell enclosure is aluminum foil coated with polymer, and is designed to be

electrically neutral and insulated

+ tab – tab

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Li-Polymer Cells – SOC

  • 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 Capacity Cell markings: 9H27 – 1.62 Ah (60% SOC) 9I19 – 1.66 Ah (61% SOC)

Initial voltage 3.84 V

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Li-Polymer Cells – Cell Disassembly

  • 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

Al Pouch Negative electrode (on Cu foil) Positive electrode (on Al foil) Separator Separator O Co EDS Spectrum

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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