They’re elemental sulfur, a waste product of fossil fuel refinement, and there’s a lot of it packed into those massive yellow pyramids. According to estimates from a University of Arizona press release, “About one-half pound of sulfur is left over for every 19 gallons of gasoline produced from fossil fuels.” That comes down to one simple fact: we have more sulfur than we know what to do with.
Researchers recently reported that they may have developed a much better use for the yellow stuff. “We’ve developed a new, simple and useful chemical process to convert sulfur into a useful plastic,” lead researcher Jeffrey Pyun says in the press release. That plastic can then be incorporated into lithium–sulfur batteries to produce cheaper and lighter batteries that are really promising for electric cars, among other spiffy uses.
Researchers have previously eyed Li–S batteries for electric vehicles because of their high theoretical specific capacity and high specific energy, although previous technologies were limited by quickly dwindling charge capacities—a big problem when it comes to battery life and efficiency.
The research, published in ACS Macro Letters, was a collaboration with the University of Arizona, Seoul National University (Korea), and the National Institute of Standards and Technology.
Through a process the researchers are calling “inverse vulcanization,” they transformed the battery’s cathode by mixing elemental sulfur with primer and carbon black to create a sort of ink, which was coated onto aluminum. More specifically, the paper states that the sulfur copolymers “were synthesized by inverse vulcanization through direct dissolution and copolymerization of diisopropenylbenzene in liquid sulfur.”
Rehauling the battery’s design allowed more efficient battery cycling, bypassing that problem that plagued previous Li–S batteries. In the paper, the authors say their work shows “improved Li−S battery lifetimes out to 500 charge−discharge cycles with excellent retention of charge capacity,” a significant boost over the battery’s predecessors.
The ultimate result? A battery that is cheaper and lighter with a high capacity and long life. Watch the video above, from the ACS series Breakthrough Science, to hear more from the scientists themselves.
The paper is “Inverse vulcanization of elemental sulfur to prepare polymeric electrode materials for Li−S batteries” (DOI: 10.1021/mz400649w).
[The original paper describing the breakthrough, which was published in Nature Chemistry, is “The Use of Elemental Sulfur as an Alternative Feedstock for Polymeric Materials” (DOI: 10.1038/nchem.1624).]