Hemp Waste Could Yield Super-Cheap Graphene

By Beth Buczynski
Source: earthtechling.com

Graphene has the potential to revolutionize nearly every energy-generating technology on the planet, from batteries to solar panels. It’s lighter and stronger than almost any other material on the planet. Here’s the problem: graphene is still extremely expensive to make, so while its potential is boundless its applications have been limited.

Now, researchers at the University of Alberta are working on a way to reduce the price of making a graphene-like nanomaterial using hemp fiber, an agricultural byproduct that’s usually sent to the landfill.

Graphene is an ideal material for batteries and supercapacitors, energy storage devices designed to deliver short burst of power. Because of its high cost, however, most manufacturers must choose commercial supercapacitors that use activated carbon electrodes instead.

University of Alberta chemical engineer David Mitlin knows that finding a way to make graphene cost-competitive with activated carbon could mean huge advances in technologies that create and store energy. So, Mitlin is working on a way to “transform waste from the cannabis plant into a carbon nanomaterial that had similar properties to graphene and with a much smaller price tag,” writes Katherine Bourzac for Chemical & Engineering News.

To do so, Mitlin and his team focused on a barklike layer of the hemp plant called the “bast”, a nanocomposite made up of layers of lignin, hemicellulose, and crystalline cellulose. “If you process it the right way, it separates into nanosheets similar to graphene,” Mitlin told CEN.

By super heating the processed bast, the researchers were able to produce a thin, porous materials capable of providing a quick path for charges to move in and out, an essential characteristic of any supercapacitor. Using this material as electrodes, Mitilin built a supercapacitor with more than twice the maximum power density of activated carbon.