Thermal runaway of lithium-ion batteries and hazards of abnormal thermal environments Conference

In addition, we have made editorial amendments to §§ 171.11, 171.12, and 171.12a to address changes in regulatory citations. In August and October of 2006 and March of 2007, several leading computer manufacturers recalled nearly 10 million notebook computer secondary lithium batteries based on manufacturing defects. The batteries in the 2006 recalls, manufactured by Sony Energy Devices Corporation, were voluntarily recalled in coordination with the U.S. According to CPSC reports, these defective secondary lithium batteries can spontaneously overheat and cause fires. The batteries in the March 2007 voluntary recall were manufactured by Sanyo Electric Company, Ltd. and designed to be extended-life batteries for Lenovo ThinkPad notebook computers. According to CPSC, the Sanyo lithium-ion batteries pose a fire hazard if the battery is struck forcefully on the corner (e.g., a direct fall to the ground).

The rule adopted in this proceeding strengthens the current regulatory framework by imposing stricter and more effective safeguards, including design testing, packaging, and hazard communication measures, for certain types and sizes of lithium batteries in certain transportation contexts. Lithium batteries are considered a hazardous material for purposes of transportation regulation because they can overheat and ignite in certain conditions and, once ignited, can be especially difficult to extinguish. In general, the risks posed by lithium batteries are a function of battery size (the amount of lithium content and corresponding energy density) and the likelihood of short-circuiting or rupture. By comparison to standard alkaline batteries, most lithium-ion batteries manufactured today contain a flammable electrolyte and have a very high energy density. A lithium battery is susceptible to thermal runaway, a chain reaction leading to self-heating and release of its stored energy.

Thermal Runaway of Lithium-Ion Batteries and Hazards of Abnormal Thermal Environments.

Thus energy ratios published using other methods and other types of Li-ion cells can be significantly different7,52,53. The heat release rate (HRR) and the emitted HF for B-type cells with different SOC values are shown in Fig. Only the 100% SOC cells show several distinct peaks, corresponding to intense flares, when the cells vented and the emitted gas burn, for all other cells the heat release as a function of time is more smooth.

In addition, FEDCO states the testing of its existing 450 primary lithium and secondary lithium battery designs will cost an additional $9 million. FEDCO proposes an exception from the proposed tests for batteries and battery packs consisting of cells that have passed the UN tests; the exception would permit the batteries and battery packs to be transported without further testing. NEMA recommends PHMSA either eliminate this restriction on products shipped with or contained with primary lithium batteries and cells or clarify the weight restrictions for primary lithium batteries and cells. NEMA also states PHMSA should expand the provision relating to products to cover lithium batteries shipped with accessories or other non-hazardous materials.

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PRBA, FEDCO, SION, Valence Technology, ACR, SkyBitz Inc, EIA, and Intel Corporation all suggest an exception, consistent with the international regulations, from marking, packaging, and shipping paper requirements for equipment containing small lithium batteries and cells. In order to further improve the accuracy of the FTIR measurements, a data offset determination and a subsequent adjustment of the HF values was performed. The improvement was greatest for tests with lower concentrations, closer to the MDL value, e.g. type A with 5 cells with low values during relatively short periods of time. With 10 cells per test, the type A batteries gave higher signal-to-noise levels. The FTIR measurements started around 8 minutes before the burner was started.

In addition, 15–22 mg/Wh of another potentially toxic gas, phosphoryl fluoride (POF3), was measured in some of the fire tests. Gas emissions when using water mist as extinguishing agent were also investigated. Fluoride gas emission can pose a serious toxic threat and the results are crucial findings for risk assessment and management, especially for large Li-ion battery packs. A104 The net weight of secondary lithium batteries or cells contained in equipment may not exceed 5 kg (11 pounds) in packages that are authorized aboard passenger carrying aircraft. PRBA, FEDCO, SION, Valence Technology, ACR, SkyBitz Inc., EIA, and Intel Corporation request several exceptions to the testing requirements for small lithium batteries. They ask us to include an exception for single cell lithium batteries, an exception for small production runs, and a delay in the effective date of the rule.

Toxic fluoride gas emissions from lithium-ion battery fires

In case the emitted gas is not immediately ignited the risk for a gas explosion at a later stage may be imminent. Li-ion batteries release a various number of toxic substances14,15,16 as well as e.g. At elevated temperature the fluorine content of the electrolyte and, to some extent, other parts of the battery such as the polyvinylidene fluoride (PVdF) binder in the electrodes, may form gases such as hydrogen fluoride HF, phosphorus pentafluoride (PF5) and phosphoryl fluoride (POF3). Compounds containing fluorine can also be present as e.g. flame retardants in electrolyte and/or separator17, in additives and in the electrode materials, e.g. fluorophosphates18,19, adding additional sources of fluorine. We believe that overall cost of the rule for small businesses is substantially less than $2.50 per shipment.

SION Power asserts eliminating the exception for medium-size lithium batteries will adversely affect its commercial development and suggests that, in the case of primary lithium batteries, eliminating the exception will limit the size of batteries using smaller cells. SkyBitz favors scaling back the exception for medium-size lithium batteries by limiting the number of cells or batteries per package, rather than eliminating the exception. ACR Electronics, Inc. states PHMSA should retain the exception for medium-size lithium batteries provided they are contained in strong, waterproof safety equipment. To evaluate the hazards posed by primary lithium batteries in air transportation, FAA’s Technical Center initiated a series of tests to assess their flammability characteristics. FAA published a technical report detailing the results of the tests in June 2004 (DOT/FAAIARI–04/26).

Those who wish to voluntarily apply the “Cargo Aircraft Only” label on excepted packages of primary lithium batteries are encouraged to coordinate with all parties in their transportation chain. In its comments, PRBA refers to the NPRM published on May 6, 2004 by PHMSA under Docket HM–224B (69 FR 25469), which proposed a requirement for oxygen cylinders to be overpacked in a packaging that would allow the cylinder to withstand a temperature of 400° F for 3 hours. (On January 31, 2007 PHMSA published the HM–224B Final Rule (72 FR 4442).) PRBA questioned why the lithium batteries were subjected to higher temperature tests than the 400° F proposed for oxygen cylinders.

The calculated average HF ppm noise level was treated as an offset that had both negative and positive values, ranging from extreme values of about −2 to 3.5 ppm. This offset was compensated for by assuming a constant offset value and adding positive or negative offset values to the total HF release value. Note that the reported concentration values in ppm are only valid for the measurements in the smoke duct of our specific test equipment and method. The HF and POF3 concentration values (in ppm) were used for calculating the corresponding production rates (in mg/s) using the ideal gas law and taking into account the measured ventilation flow rate in the smoke duct. The propane burner was started 2 minutes into each test, as indicated with arrows in the result figures in the paper. The burner was active as long as there was a heat contribution from the burning batteries; therefore, the burner was active for different durations of time for different batteries and SOC-levels.

Hazardous Materials; Transportation of Lithium Batteries

The packages on the pallets were damaged during handling at LAX, and this damage is believed to have initiated the subsequent fire. Northwest ground employees initially fought the fire with portable fire extinguishers and a fire hose. In some measurements reported, HF has been found, within limited SOC-variations, during the abuse of Li-ion battery cells15,16,26, as well as detected during the abuse of battery packs27. Time-resolved quantitative HF measurements on the gas release from complete electric vehicles including their Li-ion battery packs during an external fire have also been performed32.

Therefore, in this final rule we are eliminating the exception for medium-size lithium batteries and cells of all types transported by aircraft or vessel, but retaining a limited exception for ground transportation (i.e., motor vehicle and rail car). This action improves overall safety by reducing the risk of lithium battery-related incidents in the transport modes that are inherently most vulnerable to high consequence accidents, while minimizing the costs for businesses that ship lithium batteries by motor carrier or rail. The Teamsters state PHMSA failed to address the safety concerns of cargo-only aircraft transporting primary lithium batteries and cells.