Cutting Edge Progress in Flow Battery Technology


“Hourglass” Coal-Killing Steampunk Energy Storage System Could Pump More Wind, Solar Into Grid

Cleantechnica, May 26, 2016

The Intertubes have been buzzing with news of a new “hourglass” flow battery that could provide a durable, low cost energy storage system for the nation’s vast wind and solar resources. The old meme about clean power being unreliable is fast disappearing, and if the new battery pans out, that will seal the deal.

In addition to becoming an area of interest for the Energy Department’s solar and wind grid integration efforts, flow batteries are also edging their way into electric vehicle technology.


The MIT Energy Storage Breakthrough


If “lithium polysulfide” reminds you of lithium-ion batteries, you’re on the right track. The liquid in the new MIT flow battery is a slurry containing nanoscale particles of lithium, based on principles similar to that of conventional, solid lithium-ion technology. Don’t get too excited about the slurry, though. The researchers note that it’s a placeholder, and the basic system can be modified to use any number of other chemical compositions.

The demonstration model looks like a steampunk version of a window with two frames. It rests semi-horizontally on a trestle, so the angle of tilt can be easily adjusted.

Instead of having two liquids in the system, the new flow battery deploys a solid sheet of lithium in one frame (the idea was to test the concept in its simplest form before moving on to the next challenge). The slurry flows across the sheet and back again, moving through a narrow “neck” similar to that of an hourglass.

It all sounds simple enough, but one of the main obstacles was to stabilize the rate of flow in the slurry, which has been described as having the consistency of ketchup. Numerous adjustments were made until the team decided that a relatively shallow tilt would do the trick.

While the new system is a hybrid and not 100 percent flow, Chandler points out that it already demonstrates another key advantage of flow batteries compared to conventional, large energy storage systems:

While a conventional, all-solid battery requires electrical connectors for each of the cells that make up a large battery system, in the flow battery only the small region at the center — the “neck” of the hourglass — requires these contacts, greatly simplifying the mechanical assembly of the system…

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