James Tour has developed anodes comprising porous carbon made from asphalt that showed exceptional stability after more than 500 charge-discharge cycles (shown above). A high-current density of 20 mA/cm2 allows it to charged in a matter of minutes.
"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,” said Tour, who as well as being the T.T. and W.F. Chao Chair in Chemistry at Rice is also a professor of computer science and of materials science and nanoengineering.
The researchers mixed asphalt with conductive graphene nanoribbons and coated the composite with lithium metal through electrochemical deposition, combining it with a sulfurized-carbon cathode to make full batteries for testing. The batteries showed a high-power density of 1,322 W/kg and an high-energy density of 943 Wh/kg.
The carbon also eliminated the formation of dentridtes that cause short circuits, allowing the faster charging. This had been shown in an earlier anode design.
“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,” he said. “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.”