Asphalt-Nanoribbon Anode is Efficient and Resistant to Dendrites

A touch of asphalt could be the secret to high-capacity lithium metal batteries that are capable of charging 10 to 20 times faster than commercial lithium-ion batteries, according to Rice University Scientists.

Scanning electron microscope images show an anode of asphalt, graphene nanoribbons and lithium at left and the same material without lithium at right. The material was developed at Rice University and shows promise for high-capacity lithium batteries that charge 20 times faster than commercial lithium-ion batteries. Courtesy of the Tour Group

The Rice lab of Chemist James Tour developed anodes containing porous carbon produced from asphalt that demonstrated excellent stability after more than 500 charge-discharge cycles. A high-current density of 20 milliamps per square centimeter showed the material’s promise for use in rapid discharge and charge devices that need high-power density. The finding has been reported in the American Chemical Society journal ACS Nano.

The capacity of these batteries is enormous, but what is equally remarkable is that we can bring them from zero charge to full charge in five minutes, rather than the typical two hours or more needed with other batteries.

James Tour, Chemist, Rice University

The Tour lab earlier used a derivative of asphalt — specifically, untreated gilsonite, the same type employed for the battery — in order to capture greenhouse gases from natural gas. The Researchers mixed asphalt with conductive graphene nanoribbons this time and coated the composite with lithium metal via electrochemical deposition.

The lab incorporated the anode with a sulfurized-carbon cathode in order to make full batteries for testing. The batteries demonstrated a high-energy density of 943 watt-hours per kilogram and a high-power density of 1,322 watts per kilogram.

Testing showed another vital benefit: The carbon alleviated the formation of lithium dendrites. These mossy deposits attack a battery’s electrolyte. They short-circuit the cathode and anode and can cause the battery to fail, explode or catch fire if they extend far enough. However, dendrite formation if prevented by the asphalt-derived carbon.

A previous project conducted by the lab discovered that an anode of graphene and carbon nanotubes also prevented the development of dendrites. According to Tour,  the new composite is simpler.

While the capacity between the former and this new battery is similar, approaching the theoretical limit of lithium metal, the new asphalt-derived carbon can take up more lithium metal per unit area, and it is much simpler and cheaper to make. There is no chemical vapor deposition step, no e-beam deposition step and no need to grow nanotubes from graphene, so manufacturing is greatly simplified.

James Tour, Chemist, Rice University

Tuo Wang, Rice Graduate Student, is Lead Author of the paper. Co-authors include Rice Postdoctoral Researcher Rodrigo Villegas Salvatierra, Former Postdoctoral Researcher Almaz Jalilov, presently an Assistant Professor at King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia, and former Rice Research Scientist Jian Tian, currently a Professor at Wuhan University, China. Tour is the T.T. and W.F. Chao Chair in Chemistry and also a Professor of Computer Science and of Materials Science and Nanoengineering at Rice.

The research was supported by the Air Force Office of Scientific Research, EMD-Merck and Prince Energy.

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