Huge, liquid-metal battery could revolutionise the grid

A new type of battery being developed at the Massachusetts Institute of Technology (MIT) could eliminate the biggest barrier to renewable energy: the fact that the sun doesn’t always shine, the wind doesn’t always blow and the waves don’t always roll.

An efficient, cost-effective and scalable battery that could store energy from those sources could “could revolutionize the way electricity is used and produced on the grid,” according to ARPA-E (Advanced Research Projects Agency, Energy), the US agency that recently granted almost $7 million for MIT professor Donald Sadoway’s battery research.

Sadoway’s revolutionary battery concept has also attracted the attention of the French oil firm Total, which has launched a $4 million, five-year joint venture with MIT to develop the technology.

Sadoway’s innovative battery design involves the use of liquid metals kept at temperatures of about 700 degrees C. He won’t divulge details on which materials he’s studying while awaiting patents, but he says they’re both affordable and available enough to make large, grid-scale energy storage a real possibility.

Rather than focus on ways to make batteries smaller, more mobile and consumer-friendly, Sadoway aims at developing a large, stationary battery that’s meant to be used at the utility level.

“What I did was completely ignore the conventional technology used for portable power,” he said. “We’re talking about batteries of a size never seen before.”

The basic design for Sadoway’s battery involves two different liquid metals separated by a layer of salt. The two metals have a natural tendency to react with each other, and transfer energy by sending ions across the salt layer. The ions travel in the direction of one metal when the battery is being charged, and go toward the other when the battery is being drained.

Keeping the components liquid is key to building a better, more powerful battery, according to Sadoway.

“Solid components in batteries are speed bumps,” he said. “When you want ultra-high current, you don’t want any solids.”