Solving the solvent problem

MIT researchers led by Professor Ju Li report a new electrolyte solvent – DMFSA – that stabilizes the highly reactive sodium metal anode while enabling fast charging. The team used an AI-guided algorithm to screen 100,000 candidate molecules, starting from a previously identified stable sulfonamide (DMTMSA), and found that reducing solvent size improves ion transport without the usual sacrifice in stability. Sodium-metal batteries can use materials roughly 1,000 times more abundant and one-hundredth the cost of lithium, but until now no electrolyte remained stable at both electrodes while supporting acceptable charge/discharge rates. The smaller DMFSA solvent broke that trade-off in head-to-head experimental tests of 27 candidates. The work introduces a more general design principle – using solvent size and molecular similarity as guideposts – which one outside expert says could influence a wide range of future energy storage technologies. Funding included a Korean government grant and a U.S. National Science Foundation fellowship; characterization equipment was partly from the MIT.nano Characterization Facilities.