“Our device’s electro-chemical performance is on par with or better than graphene-based devices,” Mitlin says. “The key advantage is our electrodes, they are made from bio-waste using a simple process, and therefore, are much cheaper than graphene.”
The race toward the ideal super capacitor has largely focused on graphene — a strong, light material made of atom-thick layers of carbon, which when stacked, can be made into electrodes.
Scientists are investigating how they can take advantage of graphene’s unique properties to build better solar cells, water filtration systems, touch-screen technology, as well as batteries and super capacitors. The problem is graphene is expensive.
The energy storage industry is starting to take notice, thanks to new Canadian research that shows super capacitors with electrodes made fromhemp-based carbon nano sheets outperform standard super capacitors by nearly 200%
Graphene, a carbon nano-material, is considered one of the best materials for supercapacitor electrodes. Graphene is, however, expensive to manufacture, costing as much as $2,000 per gram.
Looking for a less-costly solution, researchers at the University of Alberta/National Institute for Nanotechnology (NINT) NRC, and Alberta Innovates-Technology Futures, led by chemical and materials engineering Professor David Mitlin, developed a process for converting fibrous hemp waste into a unique graphene-like nano-material that outperforms graphene. What’s more, hemp can be manufactured for less than $5000 per ton.
Hemp fiber waste was pressure-cooked (hydrothermal synthesis) at 180 °C for 24 hours. The resulting carbonized material was treated with potassium hydroxide and then heated to temperatures as high as 800°C, resulting in the formation of uniquely structured nano-sheets. Testing of this material revealed that it discharged 49 kW of power per kg of material—nearly triple what standard commercial electrodes supply, 17 kW/kg.
“We were delighted at how well this material performed as super capacitor electrodes,” says Mitlin. “This novel precursor-synthesis route presents a great potential for facile large-scale production of high-performance carbons for a variety of diverse applications including energy storage, portable electronics, uninterruptible power sources, medical devices, load leveling, and hybrid electric vehicles.
Our hemp Battery Technology will change electric automobile revolution... takes 20 minutes to charge 4 hours driving distance... hemp oil technology will store enough energy for 4 hours of driving distance. Hemp bast fiber (bast fibre is collected from the inner bark – or 'bast' – surrounding the stem of the plant), for instance, has a multi-layered structure composed of cellulose, semi cellulose, and lignin. While the inner and outer layers are are mainly composed of semi cellulose and lignin, the middle layer is primarily crystalline cellulose. This middle layer represents more than 85% of the total wall thickness and is itself a layered structure consisting of microfibrils that are 10-30 nm in diameter. The microfibrils consist of bundles of highly crystalline cellulose elementary fibrils ( about 2 nm in diameter) surrounded by semi cellulose.
"We used a hydrothermal process to remove the inner and outer layers while at the same time loosen the connections between the microfibrils in the middle layer," explains Li. "In a subsequent activation process at 700-800°C, potassium hydroxide (KOH) melt penetrates into the loose connection between the microfibers, causing full separation of layers as sheets. Meanwhile, the layers are carbonized and activated by the KOH, further reducing their thickness and generating micro and mesoporosity."The resulting carbon nanosheets (CNS) have a graphene-like, thin layer structure filled with large amount of pores. The layers are organized in a three-dimensional way, which makes it a very promising electrode materials for high-power (high-current) applications.
HEMP FIBER FOR PLANT BATTERIES
What we have to offer is an all-natural plant fiber, superior to graphene, transforming how we relate to storing energy and how it powers technology as well as forms it. Imagine the big iron data centers transformed into hemp-based racks and server shells as well as the hemp-based super capacitors powering the plant-based mountains of energy storing and supporting trillions of lines of content and video data.
We encourage our guests to watch the video (left).
A brief overview:
A super capacitor is a common tool for storing electrical energy. Graphene, a one-atom thick version of common graphite and carbon nano material is a super capacitor with conductivity achieving a far greater energy density, however it's expensive to produce at $2000/gram. The cost to manufacture hemp's super capacitor version is $5,000/ton. Hemp allows the possibility for these technological advancements using hemp-based to be realized. High performance hemp-based super capacitors will transform the way mankind relates to energy.
Published on Mar 16, 2015
This is a research assignment for the Strategy & Technology course, Spring Term 2015, at The University of Utah.