The new liquid battery has a negative electrode made of lead, which is cheap and melts easily, mixed with a dash of antimony to boost performance. This lowers its cost, as well as the heat required to liquefy the metals.
Published in the journal Nature, this latest attempt at a scalable solution for storing electricity is set for commercial demonstrations within a year and has been greeted with enthusiasm by engineers in the UK. "Sometimes, when the wind is blowing strongly, we have spare capacity available - if only we could store it, so that we could use it when the wind isn't blowing," explained Prof Ian Fells, a fellow of the Royal Academy of Engineering and former chair of the New and Renewable Energy Center.
The overall concept for the battery is relatively simple: inside a can there are three layers of very hot liquid, which separate of their own accord - "like oil and vinegar," according to the project's senior researcher Prof Donald Sadoway, of the Massachusetts Institute of Technology.
On the bottom is the very dense mixture of lead and antimony; next comes a "molten salt electrolyte" - effectively table salt, which is liquid at these temperatures; and finally a layer of lithium floats on top. When the cell is discharged, all the lithium is actually transferred to the bottom layer. However, when electricity is directed into the cell, the lithium is pulled out of the alloy layer and returns to the top.
The whole set-up has to be kept at some 450C, which is no small feat, but a vast improvement on the 700C required by an earlier design, whose electrodes were magnesium and pure antimony.
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Park Sae-jin
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