New Delhi- Scientists from IIT Delhi have found a potential solution to the problem of dendrite growth in room-temperature sodium-sulfur batteries. They hope that this new technology will help in developing a more sustainable alternative to lithium-ion batteries.

Room-temperature sodium-sulfur batteries are cheaper and more abundant than traditional lithium-ion batteries, but they have a higher risk of dendrite growth. This is due to the fact that the electrolyte in room-temperature sodium-sulfur batteries is constantly reacting with the sodium metal anode, which can cause the local surface to become highly irregular.

Another problem is that the solid electrolyte interphase in these batteries is mechanically and chemically unstable. To address this issue, the researchers used Bismuth iodide (BiI3) as an additive molecule in the organic electrolyte solution. BiI3 reduces the energy required for sodium ions to leave the solvent and enter the electrode, which improves the charge transfer kinetics. This leads to better battery efficiency and faster charging times.

The addition of BiI3 also helps in the formation of a Na3Bi alloy interphase and stable solid electrolyte interphase (SEI) on the sodium metal anode. This layer acts as a barrier that prevents the growth of sodium dendrites, which can lead to short circuits and degrade the battery's performance over time.

According to the researchers, the test-cell prototypes have demonstrated surviving at least 250 charge-discharge cycles. They believe that the new technology could be used for the development of electric vehicles and grid applications.

The study was published in the Journal of Materials Chemistry A-