Electric Vehicle Ownership: Costs, Environment, Climate, Politics

By David Herron

Lithium battery Flammability

Lithium is a soft, silver-white metal that belongs to the alkali metal group of chemical elements. Like all alkali metals, lithium is highly reactive and flammable. For this reason, it is typically stored in mineral oil. Because of its high reactivity, lithium never occurs free in nature, and instead, only appears in compounds, which are usually ionic. (en.wikipedia.org) http://en.wikipedia.org/wiki/Lithium

That is, because Lithium is so reactive it is always found bound into other compounds.

Lithium is present nearly everywhere but in low concentrations. It is most often commercially extracted via evaporation ponds on dry salt lake formations. Most lithium is produced in salar's in Chile and Bolivia.

For the purposes of this website we are solely interested in their use in batteries.

Types of lithium batteries

TODO TBD [[include types-of-lithium-batteries]]

Safe types of lithium batteries

The reports referenced below contain alarming stories of fires and explosions that occur with some sorts of lithium batteries. Obviously electric vehicles must have safe batteries and a lot of research is identifying lithium battery chemistries that are safe (do not explode).

(www.technologyreview.com) Berkeley, CA-based startup Seeo, Inc. has developed a battery based on solid polymers. They are supposed to be safer, longer-lasting, lighter, and cheaper than current batteries. Many kinds of lithium-ion batteries use lithium cobalt oxide electrodes and a liquid electrolyte, typically lithium salts dissolved in an organic solvent. Batteries having this chemical makeup can explode and catch fire in the right conditions.

() SRI International Introduces First Nonflammable Lithium Ion Battery For Consumer Products is an SRI press release from 1998 announcing the first non-flammable electrolyte for lithium-ion batteries. In 1998.

Laptop and cell-phone fires

If you watch the news you'll occasionally see reports of laptops or cell phones blowing up. Ponder where you normally carry your cell phone, and what body parts are near that location. Are you sure you want to do this? In 2006-7 there was a spate of laptop fires that caught a lot of attention.

(www.telegraph.co.uk) Cambridge scientists solve mystery of flammable laptop batteries is a 2010 report identifying dendrite formation as the culprit in these fires. Dendrites are lithium-metal fibers that form in battery cells in certain circumstances (high charge rates, for example) and can cause an internal short in the battery. The internal short causes a rapid discharge which leads to the battery explosion.

Lithium Battery Safety: Good Batteries gone Bad (US Navy, Naval Sea Systems Command, NAVSEA; 2005)

A 2005 study by NAVSEA, (proceedings.ndia.org) Lithium Battery Safety: Good Batteries gone Bad, evaluated the safety of military use of lithium batteries. The military (Navy, Marines and Army in this study) have a growing array of batteries, of all kinds, being used in all kinds of equipment in all kinds of situations. It would obviously be a military hazard if combat equipment (which is increasingly computerized with mobile electronics hardware) were susceptible to lithium battery fires. The US DOT flammability assessment referenced below describes the extreme explosive flammability of some lithium batteries.

The types of devices they considered range from outright weapons like torpedo's or missiles, to portable communication and battlefield planning equipment. The list was presented in 2005 and one imagines that the advances of mobile computer technology since then have trickled down to military use. One imagines a battle hardened iPad sort of device could make a very nice battlefield planning widget.

The difference between good batteries and bad batteries is this:

  • Good batteries are releasing their energy in a controlled way to power devices
  • Bad batteries are in an uncontrolled release which can result in venting, fire, release of toxic fumes, shrapnel, high pressure events, fire, and explosion. And many combinations thereof. Read the paper referenced in the DOT flammability assessment for examples.
Likely scenarios are
  • Physical abuse such as puncturing or crushing
  • Overcharging due to control electronics failure
  • Charging primary (non-rechargeable) batteries
  • Exposure to inappropriate environment conditions such as high heat
  • Short circuiting

Flammability assessment of Bulk-Packed primary lithium batteries (US Dept of Transportation; 2004)

A 2004 study by the Dept of Transportation and the FAA titled, (www.fire.tc.faa.gov) Flammability Assessment of Bulk-Packed non-Rechargeable Lithium Primary Batteries in Transport Cargo Aircraft DOT/FAA/AR-04/26, studied small-cell nonrechargeable lithium cells to see how flammable they are, and what can be done to mitigate the flammability. What they found was disturbing. At that time no known incident had occurred, but they cite a 1999 incident on a cargo ramp at LA International Airport. A pallet of batteries caught fire while being handled between flights. There was no known ignition source, they simply caught fire, and the fire was hard to extinguish.

The test used two types of then-common primary lithium cells:- CR2 and PL123A

  • The researchers found that lithium fires do not extinguish when sprayed by Halon 1301 fire suppressant. Instead the lithium metal simply changes color and keeps on burning. The types of battery they tested are relatively easy to set on fire, requiring only a small fire source. The outer plastic shell melts, the batteries then fuse together (the study assumes batteries in bulk shipment air cargo containers), and then the batteries themselves catch fire.
  • A burning lithium primary cell is hot enough to ignite neighboring cells, who then can ignite their neighbors, causing the fire to propagate naturally until all cells are consumed
  • The ambient temperature of a cargo hold where a fire was suppressed by Halon 1301 can be higher than the auto-ignition point of these kind of primary lithium batteries.
  • Ignition of primary lithium batteries in a cargo container, can puncture the container, spewing molten lithium metal out of the container, allow flames to escape the cargo container, .. doesn't paint a pretty picture
  • There's essentially little that can be done to extinguish a lithium fire
  • The autoignition temperature of pure lithium is 355 degrees F while temperatures in cargo holds where a fire has been suppressed with Halon 1301 can reach the 400-1000 F range.
  • An example of one of their tests was to place a single Sanyo CR2 cell in a wire basket above a propane fire source. Within 30 seconds the plastic shell melts, and within a minute the cell vents electrolyte gas which ignites in a bright red flame. Once the electrolyte burns off after about 1 1/2 minutes the lithium catches fire in an explosive brilliant white flame. And then the battery cell explodes.

AT&T misfortune with lithium metal batteries from Avestor - which exploded

AT&T's U-verse network cabinets were built using lithium batteries from Avestor to provide backup power supply. They deployed over 17,000 of these cabinets around the U.S. and then ran into serious problems when batteries in equipment cabinets began exploding.

"Following incidents involving batteries used in AT&T U-verse network cabinets, the company is replacing 17,000 similar batteries, all manufactured by Avestor. Normally, we would work with a vendor to diagnose problems and develop solutions. We can't do that in this case because Avestor filed for bankruptcy in October 2006 and closed shortly thereafter. As a result, we have decided to move forward with the removal of all Avestor batteries as quickly as possible," wrote an AT&T spokesperson. (www.lightreading.com) http://www.lightreading.com/document.asp?doc_id=143185

Lithium battery Flammability

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