The article doesn't have any specifics, but the group has been publishing in this area for a few years: http://sadoway.mit.edu/ http://sadoway.mit.edu/ It's an

The article doesn't have any specifics, but the group has been publishing in this area for a few years: http://sadoway.mit.edu/ http://sadoway.mit.edu/ It's an electrochemical cell - I know some people who've worked on the project and IIRC some of the main benefits are lower material cost / kWh and improved lifetime as the liquid metal "electrodes" don't degrade the same ways solid ones do.