Nano-scale Thermal Conduits for Creating High Power Thermoelectric Waves from Stored Chemical Energy

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Inventors
Professor Michael Strano
Department of Chemical Engineering, MIT
External Link (web.mit.edu)
Joel Abrahamson
Department of Chemical Engineering, MIT
WonJoon Choi
Department of Mechanical Engineering, MIT
Jae-Hee Han
Department of Chemical Engineering, MIT
Managed By
Christopher Noble
MIT Technology Licensing Officer - Clean and Renewable Energy
Patent Protection

Nanoscale thermoelectric wave generators

US Patent 8,941,285
Publications
Energy generation using thermopower waves: Experimental and analytical progress
AIChE Journal, 59(9) 2013: p.3333 - 3341

Applications

Two dimensional nanotubes and nanonetworks, such as graphene, are able to reach thermal conductivities that exceed those of conventional materials by orders of magnitude. Controlling the rate and direction of energy release from these materials may lead to more efficient chemical energy conversion processes and devices. This technology can be used to create electromagnetic pulses for intermittent but high load operations (such as emission of a modulated RF signal), thermopower wave propagation, energy storage, and thermally-triggered electromagnetic pulse.

Problem Addressed

Environmental energy scavenging can regenerate storage devices, but the maximum power capable remains insufficient for RF communications over practical distances. Therefore, there is a need to develop new types of power sources that provide peak power density for intermittent but high load operations, such as emission of a modulated RF signal or powering a fuse. This technology demonstrates encouraging power densities, surpassing the experimental values of micro lithium-ion batteries. As a result, the invention increases the power of "small volume" batteries that will be capable of generating sizable thermopower waves. 

Technology

This invention describes the generation of a high power electrical pulse from sub-mm3 devices. A carbon nanotube, a high aspect-ratio molecule with a large phonon thermal conductivity, is used to launch a thermopower wave along its length, which provides a useable power pulse from a sub-micron scale component. The invention is implemented with an annular coating of a reactive, high energy chemical around a carbon nanotube or nanowires, or by depositing a thin layer on a graphene sheet. Upon decomposition of the energetic chemical, its heat of reaction funnels into the thermal conduit where the thermal wave propagates much faster than the bulk reaction. The directed wave pushes an accompanying electron wave that generates sizeable thermopower for a device of its size. Thus, this invention leads to thermal conductivities that often exceed those of conventional materials by orders of magnitude. 

Advantages

  • Can scale to the sub-mmsize needed to power MEMS and "smart dust"
  • Thermoelecric wave with peak specific power as much as 761.6 kW/kg (6008.3 μW/mm3)
  • Reaction front velocity was 10 to 100 times faster than bulk trinitramine
  • Can be applied to collections of nanotube/nanowires for scale up