It isn’t common for a piece of research to show such immediate promise, but a recent paper published in Nature has certainly bucked the trend. An MIT Materials Professor and his graduate research assistant have discovered a way to charge and discharge lithium phosphate batteries at unprecedented rates.

Lithium phosphate cells use a liquid electrolyte, which should permit the fast transport of lithium ions from the anode to the cathode under charging conditions (according to computer models). However, the rates seen in real cells are considerably slower. What accounts for this is the behaviour of the lithium ions as they approach the cathode surface. If a lithium ion is immediately next to a channel in the cathode material, then it moves immediately into the vacancy. However, if no such channel is near by, the lithium ion takes a considerable amount of time to move to one.

The MIT researchers applied a lithium phosphate glass to the cathode which allows lithium ions to be quickly conducted across the cathode surface and into a vacancy. This has a drastic effect on charging and discharge rates, with a test cell taking between 10 and 20 seconds to completely charge or discharge, compared to six minutes for existing cells of the same chemistry.

This means that electric vehicles could potentially be charged in a matter of minutes, if the grid could supply such high currents. Furthermore, the power density of the cells is increased drastically. This has been a problem with lithium cells in the past; although they have high energy density, their ability to rapidly change to load requirements has been lacking. This is why most hybrids, including the Toyota Prius, use Nickel Metal Hydride cells (NiMH). It can be envisaged that cars with these new cells would have acceleration comparable to modern day super-cars.

And the final thing which makes this discovery so exciting: it uses a battery chemistry which is already reaching pre-eminence in electric vehicle applications. The reason lithium phosphate is so popular is that it’s inherently safe when compared to other lithium chemistries such as lithium cobalt oxide, which can deteriorate to form oxygen gas, which is of course highly explosive. Furthermore, it displays almost 100% depth of discharge, without irrevocably damaging the cells.

This is certainly disruptive technology, because it dismantles one of the main arguments put forward by pro-oil lobbyists: namely, that petrol and diesel cars are superior because they can be refilled so easily. But now it seems as if electric cars could be recharged in just a few minutes, which makes their adoption look more and more inevitable.