An ultra-thin coating material may help extend the life and improve the efficiency of lithium-sulfur batteries.

Yale scientists have developed a dendrimer-graphene oxide composite film that can be applied to any sulfur cathode—the positive terminal on a battery.

According to the researchers, sulfur cathodes coated with the material can be stably discharged and recharged for more than 1,000 cycles, enhancing the battery’s efficiency and number of cycles.

“Our approach is general in that it can be integrated with virtually any kind of sulfur electrode to increase cycling stability,” Hailiang Wang, assistant professor of chemistry at Yale and lead investigator of the study, said in a statement. “The developed film is so thin and light it will not affect the overall size or weight of the battery and thus it will function without compromising the energy and power density of the device.”

New types of electrodes—positive and negative terminals—are considered essential for the development of a new generation of high energy-density batteries.

With lithium-ion batteries beginning to reach their capacity limits, researchers are looking at lithium-sulfur as a solution.

Sulfur is lightweight and abundant, with a high theoretical energy capacity, which makes it an ideal candidate for the next generation of batteries. However, existing lithium-sulfur battery technology suffers from a loss of capacity during cycling.

The researchers were able to combine the distinct properties of two material components by merging the mechanical strength of graphene oxide with the ability of a dendrimer molecule to confine lithium polysulfides. This resulted in a gel-like slurry that can be readily coated as a 100-nanometer-thin film onto sulfur electrodes.

The study was published in the Proceedings of the National Academy of Sciences of the United States of America.