MIT's Nano Storage Could Replace Hybrid Batteries

mattnyc99 writes "Last week we discussed Popular Mechanics' reporting from MIT, but missed one of the coolest breakthrough of all, something scientists have been working on quietly as Detroit spends money elsewhere. The Lab for Electromagnetic and Electronic Systems has been doing some mega-efficient work with ultracapacitors, which store drastically less energy than a battery but have essentially none of the drawbacks — especially via carbon nanotube arrays. Automotive experts say the new research is enough to start replacing batteries in hybrid cars, and plug-in vehicles might not be far behind. From the scientist who thinks ultracapacitors are potential competitors for the pack in his Toyota Prius: 'I try to contain myself, because it hasn't been proven yet, but it could be a real paradigm change.'"

Comments

Capacitors have drawbacks too

[EmbeddedJanitor]

Even discounting the problems getting very high capacity with low ESR, capacitors still have a drawbacks. The charge is proportional to the voltage which means that the voltage keeps going up with more charge. On the discharge side it means that the voltage keeps reducing as you discharge the capacitor. Thus, the power supplies that are powered by capacitors need to work with a wider range of voltages. This tends to make them less efficient and more complex.

Re:Did anybody elses Science Teacher

[eln]

Those were for my lunch, you insensitive clod!

Ka Booooooom!!!

[Powerbear]

"And by avoiding the chemical reaction that drives traditional batteries, there's no real danger of a capacitor suddenly overloading--or exploding like a laptop's lithium-ion battery pack."

They won't explode like a lithium-ion battery pack, it will be a 100X worse.

If anything pierces the dielectric, all the energy stored in the capacitor will discharge violently in milliseconds.

Re:Ka Booooooom!!!

[fahrbot-bot]

If anything pierces the dielectric, all the energy stored in the capacitor will discharge violently in milliseconds.

I hear something like this happens with condoms too.

rtfa

[Scrameustache]

These hold less energy than batteries and yet they're going to be economically feasible? Can someone please explain to me how this is going to work, because it's not making sense to me right now. there's no battery memory caused by partial discharging and no reduction in capacity with each recharge. "They never wear out, they have no electrolyte, they don't have any chemistry taking place in them," Schindall says. "It's just an electric field that stores the energy. So you can recharge a capacitor a gazillion times. It's very efficient--just the internal resistance of the wires." The ions cling electrostatically to materials in a capacitor, which also allows for much quicker charge times. And by avoiding the chemical reaction that drives traditional batteries, there's no real danger of a capacitor suddenly overloading--or exploding like a laptop's lithium-ion battery pack.

Re:Paradigm?

[HTH NE1]

paradigm change Change for a pair of dimes
See also "nickel and dime you to death".

Re:Theoretical limit of capacitors?

[mikeee]

A capacitor has to hold the positively and negative charged portions of itself nearby, but electrically isolated; to keep the insulation from being crushed (opposite charges attract, remember) requires a certain physical strength proportinal the the charge stored that will put at least a top-end limit on capacitor capacity.

Interestingly, this is dependent (duh) on the strength (energy) of chemical bonds, so IIRC, the theoretical limit for capacitors is actually pretty much the same as for chemical fuels or batteries. (Now, small electric motors are more efficient than small engines, so electric systems can be a huge win, although the fuel system don't have to carry their own oxidizer...blah blah blah.)

Pretty much anything non-nuclear (you can throw flywheels, nanotech windup springs, and what have you in, too), should in a perfect world max out at roughly the same magnitude because they're all fundamenentally dependent on that chemical bond strength.

Re:less than batteries?

[misleb]

These hold less energy than batteries and yet they're going to be economically feasible? Can someone please explain to me how this is going to work, because it's not making sense to me right now. It sounds like they'll either have to add so many capacitors that it becomes counter productive, or else they'll have a short range and useless for road trips. Either way it won't work.

Probably already addressed adequately by other responders, but I'll chime in.

At the moment, ultra-capacitors may be best suited for systems such as hybrids where you have a constant, low power source such as a small generator in a hybrid. The idea being that you could get good power/acceleration out of a capacitor when needed and the rest of the time is spent recharging from the motor. All without the disadvantages of batteries. Think of it as a sort of electrical flywheel.

-matthew

Re:less than batteries?

[Rei]

1) Li-ion batteries use no toxic components in manufacture, and while conventional li-ions have some chemicals that are poisonous in the end products, A) the latest generations of them designed for automotive use lose those (such as using nicer electrolytes and replacing the LiCoO2 cathode), and B) they break down harmlessly once disposed (no heavy metals or the like).

2) For a given amount of charge, an ultracapacitor is a lot *heavier* than a battery bank. They're lower energy density (assuming EEStor doesn't pull off a miracle).