In this time-lapse
series of photos, progressing from top to bottom, a coating of sucrose
(ordinary sugar)
over a wire made of carbon nanotubes is lit at the left end, and burns from
one end to the
other. As it heats the wire, it drives a wave of electrons along with it,
thus converting
the heat into electricity. Courtesy of the researchers
(March 14, 2016) Battery
substitutes produce current by burning fuel-coated carbon nanotubes like a
fuse.
The batteries that power the ubiquitous devices of modern
life, from smartphones and computers to electric cars, are mostly made of toxic
materials such as lithium that can be difficult to dispose of and have limited
global supplies. Now, researchers at MIT have come up with an alternative
system for generating electricity, which harnesses heat and uses no metals or
toxic materials.
The new approach is based on a discovery announced in 2010
by Michael Strano, the Carbon P. Dubbs Professor in Chemical Engineering at
MIT, and his co-workers: A wire made from tiny cylinders of carbon known as
carbon nanotubes can produce an electrical current when it is progressively
heated from one end to the other, for example by coating it with a combustible
material and then lighting one end to let it burn like a fuse.
That discovery represented a previously unknown phenomenon,
but experiments at the time produced only a minuscule amount of current in a
simple laboratory setup. Now, Strano and his team have increased the efficiency
of the process more than a thousandfold and have produced devices that can put
out power that is, pound for pound, in the same ballpark as what can be
produced by today’s best batteries. The researchers caution, however, that it
could take several years to develop the concept into a commercializable
product.
The new results were published in the journal Energy &
Environmental Science, in a paper by Strano, doctoral students Sayalee Mahajan
PhD ’15 and Albert Liu, and five others.