Researchers at the Massachusetts Institute of Technology have advanced the development of sodium-metal batteries by identifying a new solvent that balances stability and ion transport. Sodium-metal batteries offer cost and resource advantages over lithium-ion systems, since sodium is far more abundant and less expensive. However, sodium metal is highly reactive, and conventional electrolytes undergo unwanted side reactions that degrade performance and cycle life.
In a recent publication in Joule, an MIT team led by Professor Ju Li details how the right electrolyte solvent can overcome these challenges. The researchers built on an earlier discovery of a sulfonamide-based molecule called DMTMSA, which showed exceptional stability in lithium batteries. Their goal was to find a related, smaller molecule that could maintain stability while enabling faster charging and discharging in sodium systems.
Using an AI-guided algorithm, MIT graduate student Chia-Wei Hsu generated roughly 100,000 candidate molecules in 24 hours. The team narrowed this list to 200 based on molecular shape and electronic properties similar to DMTMSA, then selected 27 for head-to-head experimental testing. The clear frontrunner was a solvent named DMFSA, which proved to be both the smallest and the most stable candidate.
Smaller solvent molecules reduce the size of the ion’s surrounding shell, allowing sodium ions to move more rapidly between electrodes. Faster ion transport supports quicker charging and higher power output, while maintaining a stable interface with both the anode and cathode. According to postdoctoral researcher Weiyin Chen, minimizing the trade-off between conductivity and stability was the key to achieving long-cycle performance under demanding conditions.
The team is now using DMFSA as a new starting point in a second round of solvent design, with the aim of discovering even better candidates. Their broader objective is to establish a general strategy for electrolyte development based on molecular size and family similarity. Such an approach could accelerate the design of high-performance, low-cost energy storage technologies beyond sodium-metal batteries.
Source: MIT News
