Liquid flow batteries — in which the positive and negative electrodes are each in liquid form and separated by a membrane — are not a new concept. The basic technology can use a variety of chemical formulations, including the same chemical compounds found in today’s lithium-ion batteries. In a new design developed by a team of MIT researchers, a liquid slurry of electrode particles is carried through a simple gravity-fed pump system, eliminating the complex system of tanks, valves, and pumps used by an earlier design.
In principle, it functions like an old-time hourglass or egg timer, with particles flowing through a narrow opening from one tank to another. The flow can then be reversed by turning the device over. In this case, the overall shape looks more like a rectangular window frame, with a narrow slot at the place where two sashes would meet in the middle.
A new concept for a flow battery functions like an old-time hourglass or egg timer, with particles (in this case, carried as a slurry) flowing through a narrow opening from one tank to another. The flow can then be reversed by turning the device over.
In the proof-of-concept version that the team built, only one of the two sides of the battery is composed of flowing liquid, while the other side — a sheet of lithium — is in solid form. The team decided to try out the concept in a simpler form before making their ultimate goal, a version in which both sides (the positive and negative electrodes) are liquid and flow side by side through an opening while separated by a membrane.
The new design should make simpler and more compact battery systems possible, which could be inexpensive and modular, allowing for gradual expansion of grid-connected storage systems to meet growing demand. The components are simple enough that they could be made through injection molding or even 3D printing. Such storage systems will be critical for scaling up the use of intermittent power sources, such as wind and solar. For more information: http://preview.tinyurl.com/hshxknq.
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