Graphene microsupercapacitors make simple, powerful energy storage possible

The Rice University researchers who pioneered the development of laser-induced graphene have formed it into flexible, solid-state microsupercapacitors that are claimed to charge 50 times faster than batteries, discharge more slowly than traditional capacitors and match commercial supercapacitors for both the amount of energy stored and power delivered.

The devices are manufactured by burning electrode patterns with a commercial laser into plastic sheets in room temperature air, eliminating the complex fabrication conditions that have limited the widespread application of microsupercapacitors. The researchers see a path toward cost-effective, roll-to-roll manufacturing.

"It's a pain in the neck to build microsupercapacitors now," James Tour, Professor of Chemistry, Materials Science and NanoEngineering, and Computer Science at Rice University, said. "They require a lot of lithographic steps. But these we can make in minutes: We burn the patterns, add electrolyte and cover them."

Their capacitance of 934µF/cm2 and energy density of 3.2mW/cm3 are said to rival commercial lithium thin-film batteries, with a power density two orders of magnitude higher than batteries. The researchers said the devices displayed long life and mechanical stability when repeatedly bent 10,000 times.

Prof Tour is convinced the day is coming when supercapacitors replace batteries entirely, as energy storage systems will charge in minutes rather than hours. "We're not quite there yet, but we're getting closer all the time," he said. "In the interim, they're able to supplement batteries with high power. What we have now is as good as some commercial supercapacitors. And they're just plastic."