New material boon for renewable energy storage
A new material could allow more utilities to store large amounts of renewable energy, says a new research.
The new electrode made of a liquid metal alloy enables sodium-beta batteries to last longer, helps streamline their manufacturing process and reduces the risk of accidental fire.
"Running at lower temperatures can make a big difference for sodium-beta batteries and may enable batteries to store more renewable energy and strengthen the power grid," said material scientist Xiaochuan Lu from US Department of Energy's Pacific Northwest National Laboratory.
More than 300 MW of large, cargo container-sized sodium-beta batteries are running in the US, Japan and Europe.
They often store electricity generated by rows of solar panels and wind turbines.
But their use has been limited because of their high operating temperature, which reaches up to 350 degrees Celsius.
Such high operating temperatures require sodium-beta batteries to use more expensive materials and shortens their operating lifespan.
Lowering the battery's operating temperature creates several other technical challenges.
Key among them is getting the negative sodium electrode to fully coat, or "wet" the ceramic electrolyte.
Lu and his colleagues took an entirely different approach to the "wettability" problem - modifying the negative electrode.
"Instead of using pure sodium, we experimented with sodium alloys, or sodium blended with other metals," Lu said.
The team determined that a liquid sodium-cesium alloy spreads out well on beta alumina membrane.
"Instead of the 350 degrees Celsius, a test battery with the new electrode worked well at 150 degrees Celsius" with a power capacity of 420 milliampere-hours per gram, matching the capacity of the traditional design," researchers said.
The research team is now building a larger electrode to test with a larger battery to bring the technology closer to the scale needed to store renewable energy, said the paper published in the journal Nature Communications.
(Posted on 03-08-2014)
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