Li-ion Batteries in Bulk Storage Benjamin Ditch Christopher - PowerPoint PPT Presentation

Flammability Characterization of Li-ion Batteries in Bulk Storage Benjamin Ditch Christopher Wieczorek SUPDET 2013, February 26 – March 1, Orlando, FL

Goal Develop sprinkler protection recommendations for bulk storage of Li-ion batteries

How to Evaluate Li-ion Batteries  Commodity classification not feasible – Expensive, cost up to $70k per pallet  Reduced commodity approach – Limit commodity to one pallet load per test – Freeburn (no water)

Combustible Product  Rack storage configuration (Li-ion batteries or standard commodity) Non-combustible – 3-tier storage – Single-row rack  Commodity lining ignition flue  Similar amount of exposed commodity for each test  Bottom tier non-combustible Ring burner  Simulate fire from 1 st tier – Propane ring burner – ~50 kW Ignition flue Side Elevation View

Reduced-Commodity Approach  Characterize fire development up to theoretical sprinkler operation – Standard commodities and Li-ion batteries  Compare predicted sprinkler operation time versus time of battery involvement  Caveat: all fire growth rates must be similar

Fire Growth Comparison CUP Heat Release Rate Class 2 Sprinkler operation Time

Commodities Standard and Li-ion Batteries

Standard Commodities Class 2 Cartoned Unexpanded Plastic

Array Configuration [50 kW] Class 2 Cartoned Unexpanded Plastic

Cylindrical Cells  Cobalt oxide  19,200 cells total  4,800 cells/pallet

Power Tool Battery Packs  200 power packs total  2,000 cells total  25 boxes/pallet

Polymer Cells  Cobalt oxide  15,552 cells total  27 boxes/pallet

Results and Analysis

Measurements*  Multiple video cameras and IR  Thermocouples at commodity/metal liner interface  Convective heat release rate *Showing only measurements used for flammability characterization

Analysis Outline  Characterization period  Fire development  Sprinkler operation predictions  Time of battery involvement

Characterization Period Period before flame spread exceeds commodity  Standard video – Attached flame location  IR video – External heating of commodity  Thermocouple liner response – Internal heating of commodity

Flame Attachment 30 s 60 s 90 s

External Heating Make/Model SC655, Temperature range 0-1,200 o C (2,190 o F) 30 s 60 s 90 s Images courtesy of Jaap de Vries

Liner TC Location Combustible Product Metal Liner 20 gauge TC, 0.4m. exposed bead (fastened to liner) 0.4m. [0.4 m = 1.3 ft] West Pallet East Pallet

Internal Heating Electrolyte oxidizes at 180 o C (360 o F) [Roth et al., SAND2004-0584, 2004 ]

Characterization Period Flame External Internal Commodity Commodity Attachment Heating Heating Collapse Class 2 60 - 90 60 - 90 n/a none CUP 60 - 90 60 - 90 160 none Li-ion 60 - 90 60 - 90 310 500 Cylindrical Cells Li-ion 60 - 90 60 - 90 120 94 Power Tool Packs Li-ion 60 - 90 60 - 90 330 540 Polymer Cells Characterization period ~ 75 ± 5 s for all commodities

Heat Release Rate 5000 CUP - Test 7 Class 2 - Test 10 4000 Convective Heat Release Rate (kW) 3000 2000 1000 0 0 60 120 180 240 300 360 420 480 540 600 Time (s)

Heat Release Rate 5000 CUP - Test 7 Class 2 - Test 10 Li-ion Cylindrical Cells 4000 Convective Heat Release Rate (kW) Li-ion Power Tool Packs Li-ion Polymer Cells 3000 2000 1000 0 0 60 120 180 240 300 360 420 480 540 600 Time (s)

5000 CUP - Test 7 Class 2 - Test 10 Li-ion Cylindrical Cells 4000 Convective Heat Release Rate (kW) Li-ion Power Tool Packs Li-ion Polymer Cells Battery Involvement 3000 2000 1000  Based on HRR curves 0 0 60 120 180 240 300 360 420 480 540 600 Time (s) – Cylindrical cells: ~ 4 - 6 minutes – Power tool packs: not discernable – Polymer cells: ~ 5 - 8 minutes  Nominal value: 5 minutes  Protection system requirement – Extinguish fire before battery involvement

Sprinkler Link Response  Measure convective flow from fire  Calculate fire plume temperature and velocity – Rack storage height – Clearance above commodity  Calculate response of sprinkler link – Link temperature rating and thermal response

Rack Storage Configuration Configuration Units Value Sprinkler RTI ft 1/2 s 1/2 50 and 300 o F Link Rating 165 Ceiling Clearance ft 10 and 15

QR Sprinkler Response Fire size @ sprinkler operation Quick-response sprinkler, 74 o C link rating, 3 m clearance (165 o F link rating, 10 ft clearance )

QR Sprinkler, 3 m (10 ft) Clearance Link Operation Time Q be Fire Growth Rate Commodity (s) (kW) (kW/s) Class 2 59 209 15 CUP 43 232 16 Li-ion 44 284 23 Cylindrical Cells Li-ion 51 282 25 Power Tool Packs Li-ion 41 256 16 Polymer Cells Fire size at sprinkler operation, Q be (kW)

Compiled Sprinkler Response (s) 3 m (10 ft) Clearance 4.6 m (15 ft) Clearance Commodity QR SR QR SR Class 2 59 77 65 90 CUP 43 70 52 86 Li-ion 44 62 76 256 Cylindrical Cells Li-ion 51 70 87 125 Power Tool Packs Li-ion 41 64 77 144 Polymer Cells Excludes all sprinkler operation times greater than 75 ± 5 s

Li-ion Polymer Cells 5000 1. QR link Convective Heat Release Rate (kW) 4000 2. SR link 6 3000 3. Batteries involved Suppression 4. Liner TC > 180 o C 2000 5 5. Partial collapse 1000 4 3 2 1 6. Fire Fighting 0 0 240 480 720 960 Time (s)

Application of Results  Hazard assessment at sprinkler operation – Storage up to 4.6 m (15 ft) – Ceilings up to 9.1 m (30 ft) – QR sprinklers, 74 o C (165 o F) rating  Small format Li-ion batteries – Cartoned in bulk storage

Conclusions  Initial fire growth similar for all commodities – Carton material  Battery involvement occurs after sprinkler operation  Battery involvement not observable for power tool packs

Future Work  Large-scale tests with Li-ion batteries – Impact of battery involvement • External fire • Internal battery fault – Impact of flaming projectiles  Bench-scale hazard assessment for other Li-ion batteries

Disclaimer  Unique test approach only used due to cost and availability of Li-ion batteries  Does not provide same information as Commodity Classification or Large-Scale testing

More data coming at… www.fmglobal.com/researchreports

Acknowledgements  Property Insurance Research Group (PIRG)  National Fire Protection Association (NFPA)  Fire Protection Research Foundation (FPRF)  Exponent Property Insurance Research Group