Flammability of Cartoned Lithium Ion Batteries

Abstract

In 2011, FPRF conducted a hazard and use assessment of lithium-ion (Li-ion) batteries with a focus on bulk warehouse storage. FPRF has now completed the next phase (Phase IIB) of this program to develop the flammability characterization in an attempt to provide the basis for fire protection guidelines of common small format battery types in rack storage configurations. Based on the previous hazard assessment (Phase I) [1], and the storage survey (Phase IIA), this research entailed full-scale fire testing of three types of small format batteries: 18,650 format cylindrical Li-ion batteries, prismatic Li-ion polymer batteries of comparable capacity to the test 18,650 cells, and packaged power tool rechargeable battery packs with cylindrical cells. Standard commodity classification testing typically involves three to four fullscale fire tests of eight or more pallet loads of the commodity. Due to the inordinate costs of acquiring pallets of Li-ion batteries, which may contain over 20,000 batteries, a modified approach was executed by FM Global. This modified approach benchmarked the flammability of a smaller quantity of cells/packs strategically arranged in a rack storage configuration against standard commodities in the same configuration and permitted testing of a reduced amount of commodity. Li-ion chemistry has become the dominant rechargeable battery chemistry for consumer electronics. This chemistry is different from previously popular rechargeable battery chemistries (e.g., nickel metal hydride, nickel cadmium, and lead acid) in a number of ways. From a technological standpoint, because of high energy density, Li-ion technology has enabled or improved entire families of devices, such as laptops, power tools, cameras, and cell phones. The increased utilization of these devices has led to an influx of the bulk storage of Li-ion batteries and heightened the need for sprinkler protection options that address the hazards associated with Li-ion battery bulk storage fires. Fire challenges associated with the bulk storage of Li-ion batteries are unique given the presence of a flammable organic electrolyte within the Li-ion battery as compared to the aqueous electrolytes typically found in other widely used battery types. When exposed to an external fire, Li-ion batteries can experience thermal runaway reactions resulting in the combustion of the flammable organics and the potential rupture of the battery [2]. NFPA 13, Standard for the Installation of