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

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:  The FPRF and the project sponsors for giving Exponent the opportunity to complete this work  The project Technical Panel for their many comments and suggestions  The Property Insurance Research Group (PIRG) 1100034.000 C0T0 0213 RTL1

3 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 1100034.000 C0T0 0213 RTL1

4 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) 1100034.000 C0T0 0213 RTL1

5 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 1100034.000 C0T0 0213 RTL1

6 What is a Li-ion Cell? 1100034.000 C0T0 0213 RTL1

7 What is a Li-ion Battery?  A Li-ion battery pack contains  An enclosure  One or more cells  Protection electronics 1100034.000 C0T0 0213 RTL1

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 Blockage in windings center of cell Pressure Open center buildup at of cell base 1100034.000 C0T0 0213 RTL1

9 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 1100034.000 C0T0 0213 RTL1

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 and packs can be contained in packaging to prevent mechanical and external short circuit damage  Fire suppression strategies 1100034.000 C0T0 0213 RTL1

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 1100034.000 C0T0 0213 RTL1

12 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 1100034.000 C0T0 0213 RTL1

13 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 or complete batteries 1100034.000 C0T0 0213 RTL1

14 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 1100034.000 C0T0 0213 RTL1

15 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 1100034.000 C0T0 0213 RTL1

16 Survey  Conducted in 2012  Responders were typically engaged in:  Manufacturing  Research  Recycling  Almost all responders stored batteries, cells, or devices with batteries/cells. 1100034.000 C0T0 0213 RTL1

17 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. 1100034.000 C0T0 0213 RTL1

18 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 3.3 g 2.6 g 4.0 g electrolyte solvent Cell chemistry Lithium Nickel Lithium Cobalt Oxide Lithium Cobalt Oxide Manganese Cobalt (LCO) (LCO) Oxide (NMC) Approx. state of charge 50% 40% 60% (SOC) as received 1100034.000 C0T0 0213 RTL1

19 Ryobi P104 Power Tool Packs – Overview Onboard “fuel gauge” indicator lights orange, indicating mid state of charge 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 1100034.000 C0T0 0213 RTL1

20 Ryobi P104 Power Tool Packs – Construction Protection printed circuit board (PCB) / Bottom View Hard injection-molded Battery Management Unit (BMU) plastic shell Soft foam padding Flexible rubber padding Hard plastic Rubber feet frame 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 1100034.000 C0T0 0213 RTL1

21 Ryobi P104 Power Tool Packs – Characterization (+) side (with vent port) (-) side (no vent port) Positive terminal and vent port • 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 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. 1100034.000 C0T0 0213 RTL1