CHAPEL HILL — A team led by one of North Carolinas most prominent scientists has found a potential solution to the notorious high-tech battery fires in Boeings new 787 Dreamliner, the Tesla Model S car and iPhones such as the one that burst into flames in a Maine eighth-graders pocket two weeks ago.
The researchers, led by Joseph M. DeSimone, have found a nonflammable liquid electrolyte for high-capacity lithium-ion batteries. Such batteries power some electric cars and are common in consumer electronics such as cellphones, tablets and laptops. They now use a flammable liquid that can ignite because of malfunctions or damage.
The discovery is the subject of an article published Monday in the Proceedings of the National Academy of Sciences. DeSimone, a chemical engineering professor at N.C. State University and a chemistry professor at UNC-Chapel Hill, is one of the authors.
The first author, Dominica Wong, is a graduate student in his chemistry lab at UNC-CH. The other authors include two scientists at the University of California, Berkeley, who DeSimone brought aboard when it became clear that his team needed help from battery experts.
In addition to potentially solving the fire problems, the discovery may also pave the way to batteries that work better at extreme temperatures and hold enough energy to substantially expand the range of electric cars, DeSimone said in an interview. Issues with driving range are one of the biggest barriers to electric cars more widespread acceptance by consumers.
Such improvements in batteries have long been the goal of intense and widespread scientific research, and experts caution against too much excitement.
Because batteries are such a popular issue these days, it helps to be a little skeptical, said Daniel Abraham, a materials scientist at the Argonne National Laboratory in Illinois. He is one of the worlds leading experts on lithium-ion batteries.
Big questions, he said, include whether batteries made with the new electrolyte can demonstrate the same sort of performance characteristics as current batteries, including capacity and longevity. Nonflammable batteries have been built before that werent able to hold as much energy, to discharge it well or to go through the substantial number of charging cycles that it takes to make them practical.
After quickly scanning the journal article on the findings, Abraham said that the researchers would have to increase the performance of the batteries made with the electrolyte as they refine the idea.
Of course, if they really have a nonflammable battery with good performance characteristics, the world will come knocking on their door, he said.
DeSimone is the Chancellors Eminent Professor of Chemistry at UNC-CH and the William R. Kenan, Jr. Distinguished Professor of Chemical Engineering at N.C. State University. He won the 2008 LemelsonMIT Prize, a $500,000 award that is regarded as the equivalent of the Nobel Prize for inventors, and he holds more than 140 patents, with dozens more pending.
He is known for not only an interest in a wide array of scientific topics, but also for spotting discoveries that have commercial potential and getting them to market.
Among them are:
• An environmentally safer method of manufacturing high-tech plastics such as Teflon.
• A plastic stent that keeps a blood vessel open after a balloon-angioplasty for a blockage, then is absorbed into the body after its no longer necessary.
• A method of making nanoparticle carriers for targeted delivery of drugs.
He has started several companies to commercialize his discoveries.
DeSimone said the key finding that makes the new batteries possible that lithium salts would dissolve in a liquid called perfluoropolyether, or PFPE is seminal.
The PFPE-based electrolyte has shown performance characteristics that bode well for its practical use and make it different from previous nonflammable alternatives tested by scientists, DeSimone said.
We think its a big deal, he said. Batteries are becoming increasingly important. Safety is increasingly important. And the range of applications that batteries are being put into is increasingly diverse, and so safety is going to be always with us.
The battery discovery was part of his teams earlier research with liquid PFPE, an extremely slippery material that is used as lubricant for machinery and looks similar to baby oil.
It came by accident during a search for a replacement for the toxic paints that the U.S. Navy uses to prevent marine organisms from attaching to the bottoms of ships and hulls of submarines. Such growth, the scourge of seafarers since the first ship was floated, can significantly slow naval craft, make them use more fuel and can make it easier for an enemy to detect submarines.
DeSimones team found that the odd liquid had characteristics similar to the flammable hydrocarbons used for electrolytes. After a few years of initial lab work, Wong, who has spearheaded the project for DeSimones lab, began flying to California to work for weeks at a time to work with the researchers based in Berkeley, helping them hone the battery design.
The researchers have been working on the project for about five years and have built several successful working batteries. They have applied for patents, and DeSimone said its now time to start seeking a commercial partner, such as a major battery manufacturer, or otherwise finding a way to continue developing the commercial possibilities of the discovery.
The implications may be greatest for automobiles, where lighter, more efficient batteries are one of the most significant bottlenecks to wider public acceptance.
DeSimone said that the performance characteristics of the new electrolyte have lead researchers to believe that it could be useful in making practical a different kind of technology that is something of a holy grail for battery scientists a lithium-air battery. That, he said, would be a huge advance, as it could more than double the distance an electric car can travel between charges.
For now, though, the next steps include coming up with designs for other components to allow the batteries to function better with the new electrolyte and to test them to make sure they can handle the number of charging cycles to make them practical, Wong said.
The small experimental versions have shown no problems with handling 30 or 40 cycles, but the researchers havent had the chance to rig the lab to allow them to try the more than 1,000 cycles it would take to prove theyre commercially viable, she said.