Advertisement

'Flow Cells' May Let Electric Cars Recharge With Liquid Refills

Follow John

A sample of Cambridge crude liquid battery material

A sample of Cambridge crude liquid battery material

Enlarge Photo

Just two months ago, we published an April Fool's piece about a fictional new BP cell research project that would allow battery packs to be refilled at fuel station pumps.

Truth is stranger than fiction, truly.

Yesterday, the Massachusetts Institute of Technology described a nascent research project--a real one--involving a battery that could recharge fully in mere minutes, by pumping out and refilling tanks that contain thick liquids that serve as the cell's electrodes.

Liquid electrodes

The idea is that the cell's cathode and anode are not solid metallic compounds, as in current battery types from lead-acid to lithium-ion. Instead, each electrode is composed of small particles suspended in a special carrier liquid that includes the electrolyte.

Those tanks of liquid could be in separate locations within a car body from the chamber (or "battery") in which they come together, exchange ions, and thereby generate electric power.

To release energy stored in the battery, the liquids would be pumped into that chamber, permitting ions to travel through a porous membrane separating the liquid cathode from the liquid anode, producing electricity.

To store energy or "charge" the battery, electricity would be input as needed to separate the particles that make up each electrode.

Tank swapping?

Alternatively, though, drivers could also pull up to a station that would pump the used liquid out of the battery chamber, and fill each separate electrode tank with fresh liquid. They could be on their way in minutes, rather than hours.

Better Place battery-swap demonstration

Better Place battery-swap demonstration

Enlarge Photo

Or, the pair of tanks might even be swapped out entirely for new tanks containing fresh electrode liquids.

That's similar to the Better Place concept for battery swap stations that replace an electric car's depleted battery pack with a fully charged one. The MIT concept, however, doesn't require an entire battery to be swapped--just tanks containing liquid electrodes.

The liquid itself, nicknamed "Cambridge crude" (for MIT's location in Cambridge, Massachusetts), is projected to cost less to manufacture per kilowatt-hour of stored energy than today's lithium-ion cell electrodes.

So-called 'flow cell'

This kind of battery is known as a "semi-solid flow cell," a new twist on the old concept of a "flow cell" that conventionally required high-volume pumping and was limited by low energy densities.

Tesla Motors - Model S lithium-ion battery pack

Tesla Motors - Model S lithium-ion battery pack

Enlarge Photo

Because it holds far higher energy, the liquid can "ooze" into the chamber rather than requiring rapid pumping.

The new cell created at MIT has 10 times the energy density of previous flow cell designs, making it theoretically cost-competitive with today's pricey lithium-ion cells. It would also, say the researchers, require only half the overall volume in a car as today's lithium-ion battery packs.

Such a design can use any one of a number of different chemistries, or electrode materials.

Working battery in 2013

The technology has been licensed by MIT to 24M Technologies, a startup that has raised $16 million toward the development costs of commercializing the technology.

Under the terms of a grant from the Defense Advanced Research Projects Agency (DARPA), the company must have a fully-functioning prototype battery system by late 2013.

For more details, especially if you're up on your chemistry, the basic research is described in a paper by its inventors.

[MIT News via MotorAuthority; hat tip: Neil Carmichael]

Advertisement
 
Follow Us

 

Have an opinion?

  • Posting indicates you have read this site's Privacy Policy and Terms of Use
  • Notify me when there are more comments
Comments (6)
  1. would we still be able to recharge at home during the intervals between when the tank needs full replacing ?
     
    Post Reply
    Vote
    Bad stuff?

  2. Yes, technically you should be able to recharge it at home, the pumping option is in a effect a method fast charge.
    Whether they choose to let you is down to the eventual manufacturer
     
    Post Reply
    Vote
    Bad stuff?

  3. Very cool technology. But there is a long road from prototype to market. That is particularly true for anything as complex as battery chemistry.
     
    Post Reply
    Vote
    Bad stuff?

  4. I suspect that this will be a race to cost effectiveness that li ion batteries will probably
    win, given the advances by DBM-Energy recently.
    They claim less volume, but more important is weight.
     
    Post Reply
    Vote
    Bad stuff?

  5. Another problem with this technology is its very high infrastructure costs. A level 3 recharge station costs nothing to operate, whereas the liquid technology scheme requires lots of supporting apparatus, personnel, etc. That has to be accounted for in any cost comparisons.
     
    Post Reply
    Vote
    Bad stuff?

  6. Hook that up to EEStor and you've really got something, LOL.
     
    Post Reply
    Vote
    Bad stuff?

 

Have an opinion? Join the conversation!

Advertisement

Find Green Cars

Go!
Advertisement

Advertisement

 
© 2014 Green Car Reports. All Rights Reserved. Green Car Reports is published by High Gear Media. Send us feedback. Stock photography by Homestar, LLC.