Hemp shows promising advantages in the field of electronics as a substitute of graphene in electrical capacitors or “supercapacitors”.

Electrical hemp: efficient supercapacitors

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Benito Díaz

Hemp uses keep multiplying in a shocking manner. This crop, considered one of the most versatile and useful of all times, shows promising advantages in the field of electronics; specifically as a substitute of graphene in electrical capacitors or “supercapacitors”.

A capacitor is a device used to accumulate electrical charge in one or more pairs of conductors separated by an insulator. Batteries have variable charge densities and work more efficiently when energy is consumed slowly and in a controlled way. These devices are used to help batteries in operations that require great amounts of power, compensating the tension in batteries and recapturing most of the production in the regenerative braking, therefore using the excess of energy, a problem that up until today affects all batteries, and that shortens their lifespan.

Supercapacitors

The power that a capacitor can contain depends on the material it is made of. A high conductivity means more electrons can share a specific area, which improves the charge density substantially. That is why they are called “supercapacitors”.

A supercapacitor is a common tool to accumulate electric power. Graphene, a one-atom-thick version of common graphite and a carbon nanomaterial, is a supercapacitor that achieves a much higher power density. It is, nevertheless, much more expensive to produce, reaching 2000 dollars a gram. The cost of producing the hemp version is 5000 per ton. Our company studies the possibility of making these advances by using hemp. These high performance materials based on hemp will transform the relation humans have with energy”, according to sources from Titan Hemp, a company devoted to developing hemp-derived materials.

Hemp batteries

The use of this material might seem innovative, but it is not really. It was discovered in 2014 by a team of scientists from the University of Alberta, led by the chemical engineering and materials professor David Mitlin.

Supercapacitors are produced out of hemp fibres, the same used in textile and paper industry, or in automotive and construction. Mitlin and his team used a very cheap material that is usually discarded.

The process has two phases. To simplify, in phase one fibres are heated for 24 hours to 176ºC. The resulting material is exposed to a more intense heat during a brief period, forming nano-layers of carbon, that are stacked to create electrodes to which an ionic liquid is added, an electrolyte that increases its storage capacity. The substance obtained holds as much energy as graphene and it’s less expensive to produce, in terms of power and price.

We love how well this material works to produce supercapacitor electrodes”, Mitlin explains. “This new route to produce synthetic precursors presents great potential for easy production, in a large scale, of high performance carbons destined to a variety of different uses, such as energy storage, portable electronics, sources of uninterrupted energy, medical devices, charge balance and hybrid electrical cars”.

They work in temperatures below 0ºC and possess one of the best combinations of energy power ever reported by any carbon. For instance, in a really high power density of 20 kw/kg and temperatures of 20ºC, 60ºC and 100ºC, the energy densities are 19, 34 and 40 Wh/kg (Watt-hour per kilogram) respectively. Once active, the power density is 12 Wh/kg, and can be obtained in a charge time under six seconds”, claims the scientist.

The research on supercapacitors is just another use of hemp, with huge possibilities in an economic and ecological level. It ranks in the list of reasons why hemp and cannabis deserve an integral, responsible regulation, that acknowledges the possibilities of these crops to the benefit of the whole of society.