(3/19/08) NanoPower lecture

Reminder:
Specific Power: power per each unit of mass

Radioisotope batteries: Long-term, but a small amount of current (have to wait for the half-life)
If you go for a short, quicker half-life, the battery doesn't last as long.

PMAD = Power Management and Distribution

Starshine: Looks like disco ball; used to monitor near-Earth-orbit drag
Solar activity is related to this drag; solar wind particles (sort of), but also

Nickel-metal-hydride batteries: Heavy (not the best specific power or energy density), but easily rechargeable

Lithium-ion: Better specific-power and energy density, but not as rechargeable
Lithium-ion batteries used in Earth-based electronics; so there's more R&D going on

Hydrogen fuel cells like batteries in design, but instead of passing ions back and forth, new ions (fuel) are pumped in.

Now how can nonomaterials help us with all of these power tasks?
Carbon nanotubes are used to improve performance

Inadvertent uses of nanotechnology exist farther back in history - Lycurgus cup comes to mind

buckminsterfullerenes discovered in 1980s: New ball-like form of carbon

Rolling up a sheet of paper = analogous to nanotubes. Can roll up the paper in different ways, and as such, can make different nanotubes. Some are metallic; some have varying degress of conductivity

Typically about a nanometer in diameter; can be hundreds or thousands of microns long; thus an unbelievably high aspect ratio.
Also a very-good thermal conductor
Strongest material known to man under tensile force

Solid-state physics law - Veidelman and Franz
* examined various conductors (gold, lead, etc)
* Ratio of thermal conductivity to electrical conductivity was the same for various materials
* SOme materials do violate this law, nanotubes aren't one of those.

Binding polymers used in actual battery applications, to keep the carbon-nanotube powder from getting all over the place.
Need at least 30% graphite to have conductivity
Need only one or two percent nano

Kind of like crossing a creek (creating a conductive path): Either pile rocks in, or lay one log across

Stronger, smoother plastic when nanotubes are used
Nanotube usage would speed-up the charge rate

Nanotubes group via van der waals effect.
Can make multi-wall nanotubes: easier to produce