As several panelists noted at last week’s Solar Energy Symposium in New Jersey, solar and wind energy will become a true alternative (or, at least, a greater complement) to fossil-fuel generation only when their intermittent supply limitations can be offset by large-scale and affordable storage capacity.

MIT Professor Donald Sadoway and Research Affiliate David Bradwell

A new generation of batteries to capture wind power at night (when a utility’s demand is low) or to utilize solar energy to power air conditioning units during heat waves (even on cloudy days when soar panels are producing fewer watts) is the holy grail of alternative energy research.

Today, there is promising environmental news from scientists at MIT who are working on a new type of ‘liquid battery’ that they believe could provide that storage at far lower
cost and with greater longevity than other methods

The high-temperature battery’s liquid components, like some novelty
cocktails, naturally settle into distinct layers because of their
different densities.

The three molten materials form the positive and negative poles of the
battery, as well as a layer of electrolyte — a material that charged
particles cross through as the battery is being charged or discharged —
in between. 

The negative electrode (anode) in the top layer is made of magnesium. The middle layer, the electrolyte, consists of a salt mixture containing magnesium chloride, and the bottom layer, which is the positive electrode (cathode), is made of antimony.

The system would operate at a temperature of 700 degrees Celsius, or 1,292 degrees Fahrenheit.

All three layers are composed of materials that are abundant
and inexpensive, according to Donald Sadoway, the John F. Elliott Professor
of Materials Chemistry at MIT and the senior author of the new paper reported in the Journal of the American Chemical Society.

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The inspiration for the concept came from Sadoway’s earlier work on the
electrochemistry of aluminum smelting, which is conducted in
electrochemical cells that operate at similarly high temperatures. Many
decades of operation have proved that such systems can operate reliably
over long periods of time at an industrial scale, producing metal at
very low cost. In effect, he says, what he figured out was “a way to run
the smelter in reverse.”

Over the last three years, Sadoway and
his team — including MIT Materials Processing Center Research Affiliate
David Bradwell MEng ’06, PhD ’11, the lead author of the new paper —
have gradually scaled up their experiments.

Their initial tests used
batteries the size of a shot glass; they then progressed to cells the
size of a hockey puck, three inches in diameter and an inch thick. Now,
they have started tests on a six-inch-wide version, with 200 times the
power-storage capacity of the initial version.

Read more about the MIT liquid battery research
Liquid batteries could level the load
MIT: Liquid Batteries Have Huge Potential