New Liquid-Flow Battery Could Make Charging EVs as Quick as Pumping Gas

A sample of 'Cambridge crude' — a black, gooey substance that can power a highly efficient new type of battery. A prototype of the semi-solid flow battery is seen behind the flask. Photo: Dominick Reuter

We’ve all heard the problems that come with owning an EV. Charging takes up to eight hours or more, and there’s not a charging station on every block to compete with those easily accessible and convenient gas stations. Yeah, yeah, we know, charging your EV quickly means you’ve got to set up an expensive high-speed charger in your garage. And yes, lack of public charging stations means that if your car runs out of juice you’re stuck in the middle of town, unless a friendly soul will let you charge up in their garage.

But there might be a quicker and easier way to charge your EV, thanks to a team of researchers at MIT who created a liquid-flow battery for EVs that can be recharged in the same amount of time it takes to fill up a gas tank. The battery involves a black and gooey electrolyte which holds suspended positive and negative electrodes that provide the EV with juice. When all the energy has been zapped out of the electrolyte, you can simply remove a container holding the goo from the battery and recharge it. Then you can put it back in the battery and you’re ready to go. The team at MIT envisions this happening as quickly and easily as it takes to pump gas.

By combining the traditional, stationary electrodes of a lithium-ion battery with the suspension idea of a liquid flow battery, the team makes it possible to refuel an EV without having to recharge the battery within its own structure. A refillable liquid-flow battery would be less expensive than traditional lithium ion batteries, and could help bring down the cost of electric vehicles too.

Liquid flow batteries are not new, but earlier research could not find a material that had high enough energy density to make the batteries plausible. The MIT team managed to find a material that surpassed the energy density of prior liquid flow batteries and enabled the structure to be small enough for use in EVs. Though it could take a few years before this technology is implemented, it could allow EV charging to be as simple as stopping at an public charging station and refueling in the time that it takes to grab a few snacks and pay.

Better Place, a company based in Israel, has the same vision. They are working on implementing networks of convenient charging stations and have begun installing 10 charge spots across Oahu, Hawaii in April 2011. One of their prototypes includes battery switch stations that switch new batteries for depleted ones, cool and charge the batteries in inventory, and ensure that each EV that comes to the station gets a fully-charged battery. Convenient access to EV charging stations is crucial for the technology to take off, and it seems like we’re getting closer every year. EVs will have to compete with hydrogen fuel technology, which is also seeing a rise in charging station prototypes.

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