Via: Flight Global

By: Zach Rosenberg Washington DC
11:19 29 Jan 2013

The lithium ion batteries installed on the Boeing 787 are inherently unsafe, says Elon Musk, founder of SpaceX and owner of electric car maker Tesla.

“Unfortunately, the pack architecture supplied to Boeing is inherently unsafe,” writes Musk in an email to Flightglobal.

“Large cells without enough space between them to isolate against the cell-to-cell thermal domino effect means it is simply a matter of time before there are more incidents of this nature,” he adds.

Both Boeing and Tesla use batteries fueled by lithium cobalt oxide, which is among the most energy-dense and flammable chemistries of lithium-ion batteries on the market. While Boeing elected to use a battery with a grouping of eight large cells, Tesla’s batteries contain thousands of smaller cells that are independently separated to prevent fire in a single cell from harming the surrounding ones.

“Moreover, when thermal runaway occurs with a big cell, a proportionately larger amount of energy is released and it is very difficult to prevent that energy from then heating up the neighboring cells and causing a domino effect that results in the entire pack catching fire,” says Musk.

An aerospace-capable version of Tesla’s battery has been developed for use in SpaceX’s Falcon 9 space launch vehicle. SpaceX, also owned by Musk, competes with Boeing/Lockheed Martin joint venture United Launch Alliance for customers. Boeing has thus far declined offers of assistance from Tesla and SpaceX, says Musk.

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