Scientists at a Canadian university have announced a major breakthrough in lithium-sulfur (Li-S) battery technology. Using an ultrathin nanomaterial, they have developed a more durable sulfur cathode. This technology holds promise for creating lighter, higher-performing, and cheaper batteries for electric vehicles. The related paper was recently published in the journal *Nature Communications*.
According to a report on Phys.org on January 13, a new material discovered by university chemistry professor Linda Nazar and her research team can maintain the stability of sulfur cathodes, overcoming a major obstacle currently facing the manufacture of lithium-sulfur batteries. Theoretically, a lithium-sulfur battery of the same weight could not only provide electric vehicles with three times the driving range of current conventional lithium-ion batteries, but would also be cheaper. Professor Nazar, who is also the director of the Canadian Solid State Energy Materials Research Centre, said that this is a major advancement, bringing high-performance lithium-sulfur batteries within reach.
Nazar's team's research on lithium-sulfur battery technology first gained public attention in 2009. At that time, a paper published in *Nature* demonstrated the feasibility of lithium-sulfur batteries using nanomaterials. Theoretically, sulfur is more competitive as a cathode material than lithium cobalt oxide, which is currently used in lithium-ion batteries, because sulfur is abundant, lightweight, and inexpensive. Unfortunately, sulfur dissolves into the electrolyte solution, forming sulfides, causing sulfur-based cathodes to deplete within just a few weeks, leading to battery failure.
Nazar's research team initially thought that porous carbon or graphene could stabilize polysulfides through trapping. However, an unexpected twist revealed that this was not the case; the final answer was neither porous carbon nor porous graphene, but metal oxides.
Their initial research on metal oxides was published in the journal *Nature Communications* last August. While the researchers have since found that manganese dioxide nanosheets outperform titanium dioxide, the new paper primarily elucidates their working mechanism.
"Before you develop new materials, you have to focus on this phenomenon and find out how it works," Nazar said. The researchers found that the chemical activity on the surface of ultrathin manganese dioxide nanosheets could effectively immobilize sulfur cathodes, and ultimately created a high-performance cathode material that could be cycled for more than 2,000 charging cycles.
Researchers say the chemical reactions on the surface of this material are similar to those in the Wachenberger solution, discovered during the golden age of German sulfur chemistry in 1845. Nazar said, "Ironically, very few scientists now study or even teach sulfur chemistry. So we have to look to very old literature to understand this technology that could fundamentally change our future."
The paper's first author, postdoctoral researcher Liang Xiao, along with graduate students Connor Hart and Quan Pang, also discovered that graphene oxide appears to have a similar working mechanism. They are currently investigating other oxides to determine the most effective sulfur-fixing materials.
It is understood that Professor Nazar will give a more detailed presentation on this lithium-sulfur battery technology at the annual meeting of the American Association for the Advancement of Science (AAAS).
