Heat-Channeling Carbon Nanotubes Produce 100 Times More Energy than Li-ion Batteries | Popular Science: "Johnny Cash can't have known about carbon nanotubes when he sang about that burning ring of fire, but MIT scientists have shown how the tiny tubes can channel a ring of heat that creates electrical current -- about 100 times as much energy per unit of weight when compared with a lithium-ion (Li-ion) battery.
The new experiments involved nanotubes, or submicroscopic structures just a few billionths of a meter in diameter, that can conduct both electricity and heat. Engineers coated the nanotubes with reactive fuel that produces heat by decomposing, and then ignited it with laser beams or high-voltage sparks.
That set off a fast-moving heat wave that traveled through the nanotube's hollow cylinder 10,000 times faster than in the reactive fuel itself, and reached a temperature of 4,940 degrees F (3,000 Kelvin). The fast-moving heat also pushed electrons along the tube and created a noticeable electrical current.
Such combustion waves were studied mathematically for a century, according to Michael Strano, a chemical engineer at MIT. Strano first predicted that a nanotube or nanowire could channel the heat pulse and create electrical current, but now his group has realized that prediction.
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