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

Lithium metal is a promising anode material in Li-ion batteries due to its high specific capacity and extremely low electrochemical potential. The major drawback is its propensity for the formation of dendrites—the growth of whiskers that can cause the battery to short-circuit or explode.

A solution devised by Rice University researchers entails use of a porous carbon material derived from asphalt as a host material for Li plating. The asphalt was mixed with conductive graphene nanoribbons and applied via electrochemical deposition. The anode was then combined with a sulfurized-carbon cathode to make full batteries for testing.

The resulting device demonstrated exceptional stability after more than 500 charge-discharge cycles. A high-current density of 20 milliamps per square centimeter confirms the material’s promise for use in rapid charge and discharge devices that require high-power density. The batteries showed a high-power density of 1,322 watts per kilogram and high-energy density of 943 watt-hours per kilogram.

Additional benefits observed include the ability to fully charge the batteries in five minutes, rather than the typical two hours or more needed with other batteries. And the use of the asphalt derivative mitigated the formation of Li dendrites.

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