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'Cambridge crude' could let EVs refuel like gas-powered vehicles

'Cambridge crude' could let EV...
The liquid suspension that has been dubbed "Cambridge crude" (Image: Dominick Reuter)
The liquid suspension that has been dubbed "Cambridge crude" (Image: Dominick Reuter)
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Members of the research team included (from left to right) recent graduate Mihai Duduta '10, Prof. W. Craig Carter, graduate student Bryan Ho, and Prof. Yet-Ming Chiang (Image: Dominick Reuter)
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Members of the research team included (from left to right) recent graduate Mihai Duduta '10, Prof. W. Craig Carter, graduate student Bryan Ho, and Prof. Yet-Ming Chiang (Image: Dominick Reuter)
The liquid suspension that has been dubbed "Cambridge crude" (Image: Dominick Reuter)
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The liquid suspension that has been dubbed "Cambridge crude" (Image: Dominick Reuter)
A prototype of the semi-solid flow battery developed at MIT (Image: Dominick Reuter)
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A prototype of the semi-solid flow battery developed at MIT (Image: Dominick Reuter)
A prototype of the semi-solid flow battery developed at MIT (Image: Dominick Reuter)
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A prototype of the semi-solid flow battery developed at MIT (Image: Dominick Reuter)
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With consumers used to the convenience of refueling their vehicle at the gas station in a few minutes, one of the biggest disadvantages of electric vehicles is the time it takes to recharge their batteries. Now, by separating the energy storage and energy discharging functions of the battery into separate physical structures, researchers at MIT have achieved a breakthrough that could allow EVs to be recharged in the same time it takes to refuel a conventional car. The technology could also provide an inexpensive alternative for energy storage for intermittent, renewable energy sources such as wind and solar.

The new battery employs an architecture known as a "semi-solid flow cell," which sees the battery's positive and negative electrodes (cathodes and anodes) made up of solid particles suspended in a liquid electrolyte. These oppositely charged particles are pumped through systems separated by a filter, such as a thin porous membrane.

The MIT researchers say that by separating the energy storage and energy discharge functions of the battery into separate physical structures allows them to design more efficient batteries. This should allow for a complete battery system - including all its structural support and connectors - that is half the size and cost of existing rechargeable batteries.

"Recharge" in a jiffy

While such size and cost reductions alone would make them attractive for use in EVs, it is the possibility of "refueling" the battery by pumping out the discharged liquid and pumping in a fully charged replacement that could be the real game changer and make EVs more competitive with conventional gas- or diesel-powered vehicles. The technology also allows for the liquid to be recharged in the usual way when time isn't a factor. Although flow batteries have been around for a while, they have used liquids with very low energy density. This has resulted in batteries that are much bigger than fuel cells and require rapid pumping of the fluid, which also reduced their efficiency.

The liquids in the new semi-solid flow batteries developed under the leadership of MIT materials science professors W. Craig Carter and Yet-Ming Chiang, provide a 10-fold improvement in energy density over present liquid flow batteries. This means the liquid suspensions - which have been dubbed 'Cambridge crude' as they look and flow like thick black goo and could take the role of petroleum in transportation - don't have to be pumped rapidly to deliver their power.

A prototype of the semi-solid flow battery developed at MIT (Image: Dominick Reuter)
A prototype of the semi-solid flow battery developed at MIT (Image: Dominick Reuter)

Grid storage

The researchers say the new battery could also be scaled up to very large sizes at low cost, making it suitable for large-scale energy storage for utilities faced with the often difficult task of matching electricity production to demand. The technology could also help overcome the problem of storing energy from intermittent renewable energy sources such as wind and solar. At the moment the battery is built around the proven chemistry of lithium-ion batteries and better anode and cathode materials and electrolytes are needed before a practical, commercial version of the battery is viable. But Chiang says because the design architecture of the new battery "is not linked to any particular chemistry," it can be used with different chemical combinations. He and his colleagues are now exploring different possibilities and as better materials are discovered, they can be adapted to the battery's architecture.

Under a three-year ARPA-E grant awarded in September 2010, the team's target is to have a "fully-functioning, reduced-scale prototype system" that is ready to be engineered for production as a replacement for existing EV batteries by the end of 2013.

Chang and Carter have also founded a company called 24M, which has licensed the technology and has raised over US$16 million in venture capital and federal research funding.

Source: MIT News

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17 comments
jrup
Now we\'re talkin\' - I\'m already in the market for this one! MIT!
Yusuf Khan
Why can\'t they just use hydrogen fuel cells, large amount of gas can be stored with a high energy to weight ratio. Use the power source that recharges these batteries for electrolysis and you have overcome all the problems.
jpm2209
^^ The electrolysis fuel cell cycle efficiency is \"maybe 40%\" (per the Strategic Electrochemistry Research Center). Lithium-ion batteries have a 97-99% charge/discharge efficiency. True, H2 energy to weight ratio is high, but energy to volume ratio is as low as it gets. Since the energy source is electricity anyway, it makes more sense to store it in a battery at ~98% efficiency than to utilize a 40% efficient process that involves a lot of additional equipment.
Facebook User
Hydrogen is difficult to store and transport.
William Volk
Why not fuel cells? Electrolysis is only about 60% efficient and fuel cells are maybe 70% efficient. LiOn battery tech is already in the 90\'s % in charge/discharge efficiency.
Leithauser
Khan: I see two advantages over hydrogen. One is that this battery can easily be recharged directly within the battery with electricity, as well as pumped fuel. While it is true that hydrogen can be obtained by electrolysis, the process of producing, capturing, compressing, and storing it is a bit more complicated. The second is that hydrogen is explosive. Also, as a gas, it requires airtight, pressurized containers to transport and such. Just my quick take on this. I especially like the idea of being able to store energy from wind and solar with this. Since \"the wind doesn\'t always blow and the sun doesn\'t always shine\" is the biggest arguement against renewables, this could be a major step forward.
Slowburn
So much effort to make a more expensive, less effective replacement for a practical, safe, and cleaner energy source.
Gadgeteer
Khan, Hydrogen has low energy density. Whether in super-high pressure tanks, liquid form or in adsorption storage media like metal hydrides or carbon nanotubes, it doesn\'t begin to approach something like gasoline in terms of either volume or weight.
Bryan Paschke
Slowburn, what is this magical practical safe and clean energy source?
Raymond Johnson
They are simply trying to avoid using the most abundant energy source in the world. Water. Water is highly available, renewable, and virtually inexhaustible. No wonder every researcher that gets \"Paid\" is looking for a way to provide energy that is patentable, commercially monopolistic, and difficult for the average person to reproduce. They want the be the only kids on the block that can make it. Thus, the cycle of power and greed continues. We will never see any technology go mainstream that cannot be greedily controlled. ie: Nickola Tesla - Wireless electricity. They didn\'t have the technology to put a faucet on it, so guess what? It never happened.