Supercapacitors are like batteries: they store and discharge electricity. However, batteries store energy electrochemically, while supercapacitors store energy electrostatically. Batteries contain chemicals that react to create an electric current. In contrast, supercapacitors retain static electricity on a conductive electrode to be released as needed, in the same way you can amass static electricity and deliver a shock with the touch of your fingertip. This fundamental difference lets supercapacitors charge and discharge electricity faster than a battery. Supercapacitators also endure many more cycles of recharging and safely function in more extreme temperatures. These capabilities make them crucial components for advancing technologies like electric cars. Imagine charging your car in seconds and never needing to replace its electrical storage devices!
Such incredible possibilities are now closer to reality, for hemp-derived electrodes will tremendously increase the availability of sustainable supercapacitors. The hemp alternative is one thousand times cheaper and infinitely more environmentally friendly to produce than graphene, the current industry standard for supercapacitors. Graphene production requires mining graphite and using expensive and harmful chemicals. In contrast, hemp farming actually enhances the soil and requires less resources than many other crops. Various industries will process hemp to make sustainable products, and then supercapacitor makers will use the leftover hemp bast for electrodes, minimizing waste and maximizing utility. The key advantage is that our electrodes are made from biowaste using a simple process, and therefore, are much cheaper than graphene.”
Making Hemp-Based Energy Storage
Without employing costly, toxic substances, the team led by David Mitlin, PhD of Clarkson University uses a heating process to transform hemp bast into carbon nanosheets. They heat the material at 350 degrees Fahrenheit for a day and then apply a blast of extremely high temperatures. Mitlin’s team then uses these hemp-derived carbon nanosheets to power their supercapacitors, which significantly outperform current commercial models. The researchers found that “the hemp-based devices yielded energy densities [or the amount of energy a supercapacitor can store based on its volume] as high as 12 watt-hours per kilogram, two to three times higher than commercial counterparts. They also operate over an impressive temperature range, from freezing to more than 200 degrees Fahrenheit.” Truly, industrial hemp biomass would revolutionize the future of sustainable energy use and storage.
Mitlin’s team built their supercapacitors using the hemp-derived carbons as electrodes and an ionic liquid as the electrolyte. Fully assembled, the devices performed far better than commercial supercapacitors in both energy density and the range of temperatures over which they can work. The hemp-based devices yielded energy densities as high as 12 Watt-hours per kilogram, two to three times higher than commercial counterparts. They also operate over an impressive temperature range, from freezing to more than 200 degrees Fahrenheit.