Lithium ion batteries have been in use for more than two decades, but safety concerns about them have recently attracted a wave of media and regulatory attention. Fires involving the lithium ion batteries of Boeing 787 Dreamliners in January, 2013 resulted in the temporary grounding of the entire 787 fleet.
A series of 2013 fires in all-electric Tesla S autos prompted safety concerns. Publicity surrounding fires involving lithium ion battery powered hoverboards in 2015 led to issuance of Underwriters Laboratories (UL) standard UL 2272 for their electrical systems which were adopted by the Consumer Product Safety Commission (CPSC). In February, 2016, the CPSC declared that hoverboards which do not comply with the UL standard are deemed to be defective and may present a “substantial product hazard” under the Consumer Product Safety Act.
Also in February 2016, the United Nations International Civil Aviation Organization (ICAO) adopted an interim ban on cargo shipments of lithium ion batteries on passenger aircraft. The International Aviation Transport Association (IATA) followed by requiring that lithium ion batteries shipped by air must be labeled for cargo aircraft only under IATA’s dangerous goods regulations (the requirement does not apply to lithium ion batteries contained in battery powered equipment), and several U.S. airlines, including Delta and United, have prohibited shipment of lithium ion batteries as cargo on their aircraft. The Federal Aviation Administration issued a safety alert to airlines calling on them to assess the risks associated with shipment of lithium ion batteries, and the National Transportation Safety Board NTSB) recommended that lithium batteries be physically separated from flammable hazardous materials and that restrictions be placed on the quantities of lithium batteries carried by air.
What are the hazards associated with these products?
Rechargeable lithium ion batteries have become widely used because they are more efficient than prior rechargeable battery technologies for both consumer electronic products as well as heavier applications in vehicles and aircraft. They have higher energy density, low memory effect and low self-discharge rates. However, their higher energy density and efficiency carries a risk. Small metal particles and impurities within a lithium ion battery cell can cause a short circuit. A short can result in a temperature rise leading to a thermal runaway within the battery and sufficient heat to ignite the battery materials, resulting in a fire.
The principal risk presented by lithium ion batteries arises from large quantities aggregated as air cargo, where a thermal runaway and fire can rapidly spread throughout the batteries resulting in an uncontained fire capable of destroying the aircraft. The fatal accidents to UPS Flight 6 at Dubai in September, 2010 and Asiana Airlines Cargo Flight 991 in July, 2011 were both attributed to uncontrolled fires resulting from thermal runaway events in bulk shipments of lithium ion batteries. As a result of these incidents, the National Transportation Safety Board (NTSB) issued recommendations in February, 2016 calling on the FAA to require that certain flammable liquids be physically separated from bulk shipments of lithium cells and batteries and setting maximum loading densities for them on the same or adjacent pallets. And the ICAO issued technical instructions effective in April, 2016 stating that lithium ion batteries offered for air transport should be limited to a charge not exceeding 30 percent of their rated capacity.
At the other end of the spectrum, the individual lithium ion batteries that power consumer products such as laptop computers, cameras and mobile phones do not present the risk of a cascading thermal runaway event. The battery industry says that if such a lithium ion battery overheats the device should be moved away from flammable material and, if possible, the battery removed. A small lithium ion fire can be controlled with foam, and ABC dry chemical extinguishers or water.
Government, international agencies and industry have responded to the hazards of lithium ion batteries. Real world experience will show whether these measures have been successful in mitigating the risks.