Graphene supercapacitors

Graphene is a thin layer of pure carbon, tightly packed and bonded together in a hexagonal honeycomb lattice. It is widely regarded as a “wonder material” because it is endowed with an abundance of astonishing traits: it is the thinnest compound known to man at one atom thick, as well as the best known conductor. It also has amazing strength and light absorption traits and is even considered ecologically friendly and sustainable as carbon is widespread in nature and part of the human body.

Graphene is often suggested as a replacement for activated carbon in supercapacitors, in part due to its high relative surface area (which is even more substantial than that of activated carbon). The surface area is one of the limitations of capacitance and a higher surface area means a better electrostatic charge storage. In addition, graphene based supercapacitors will utilize its lightweight nature, elastic properties and mechanical strength.

Graphene-based supercapacitors are said to store almost as much energy as lithium-ion batteries, charge and discharge in seconds and maintain all this over tens of thousands of charging cycles. One of the ways to achieve this is by using a a highly porous form of graphene with a large internal surface area (made by packing graphene powder into a coin-shaped cell and then dry and press it).

What are supercapacitors?

Supercapacitors, also known as EDLC (electric double-layer capacitor) or Ultracapacitors, differ from regular capacitors in that they can store tremendous amounts of energy.

A basic capacitor usually consists of two metal plates, separated by an insulator (like air or a plastic film). During charging, electrons accumulate on one conductor and depart from the other. One side gains a negative charge while the other side builds a positive one. The insulator disturbs the natural pull of the negative charge towards the positive one, and that tension creates an electric field. Once electrons are given a path to the other side, discharge occurs.

Supercapacitors also contain two metal plates, only coated with a porous material known as activated carbon. They are immersed in an electrolyte made of positive and negative ions dissolved in a solvent. One plate is positive and the other is negative. During charging, ions from the electrolyte accumulate on the surface of each carbon-coated plate. Supercapacitors also store energy in an electric field that is formed between two oppositely charged particles, only they have the electrolyte in which an equal number of positive and negative ions is uniformly dispersed. Thus, during charging, each electrode ends up having two layers of charge coating (electric double-layer).



Supercapacitor design

Batteries and Supercapacitors

Unlike capacitors and supercapacitors, batteries store energy in a chemical reaction. This way, ions are inserted into the atomic structure of an electrode, instead of just clinging to it like in supercapacitors. This makes supercapacitors (and storing energy without chemical reactions in general) able to charge and discharge much faster than batteries. Due to the fact that a supercapacitor does not suffer the same wear and tear as a chemical reaction based battery, it can survive hundreds of thousands more charge and discharge cycles.

Supercapacitors boast a high energy storage capacity compared to regular capacitors, but they still lag behind batteries in that area. Supercapacitors are also usually more expensive per unit than batteries. Technically, it is possible to replace the battery of a cell phone with a supercapacitor, and it will charge much faster. Alas, it will not stay charged for long. Supercapacitors are very effective, however, at accepting or delivering a sudden surge of energy, which makes them a fitting partner for batteries. Primary energy sources such as internal combustion engines, fuel cells and batteries work well as a continuous source of low power, but cannot efficiently handle peak power demands or recapture energy because they discharge and recharge slowly. Supercapacitors deliver quick bursts of energy during peak power demands and then quickly store energy and capture excess power that's otherwise lost. In the example of an electric car, a supercapacitor can provide needed power for acceleration, while a battery provides range and recharges the supercapacitor between surges.

Supercapacitor vs Battery charge times

Common supercapacitor applications

Supercapacitors are currently used to harvest power from regenerative braking systems and release power to help hybrid buses accelerate, provide cranking power and voltage stabilization in start/stop systems, backup and peak power for automotive applications, assist in train acceleration, open aircraft doors in the event of power failures, help increase reliability and stability of the energy grid of blade pitch systems, capture energy and provide burst power to assist in lifting operations, provide energy to data centers between power failures and initiation of backup power systems, such as diesel generators or fuel cells and provide energy storage for firming the output of renewable installations and increasing grid stability.

Rivaling materials

Several materials exist that are researched and suggested to augment supercapacitors as much (or even more than) graphene. Among these materials are: hemp, that was used by Canadian researchers to develop hemp fibers that are at least as efficient as graphene ones in supercapacitor electrodes, Cigarette filters, which were used by Korean researchers to prepare a material for supercapacitor electrodes that exhibits a better rate capability and higher specific capacitance than conventional activated carbon and even higher than N-doped graphene or N-doped CNT electrodes.

Graphene supercapacitors commercialization

Graphene supercapacitors are already on the market, and several companies, including Skeleton Technology, the CRRC, ZapGoCharger, Angstron Materials and Sunvault Energy are developing such solutions. Read our Graphene Supercapacitors market report to learn more about this exciting market and how graphene will effect it.

Graphene supercapacitors market report

Further reading

Latest Graphene Supercapacitors news

Graphene-Info's Batteries, Supercapacitors, Graphene Oxide, Lighting, Displays and Graphene Investments Market Reports updated to July 2018

Today we published new versions of all our graphene market reports. Graphene-Info provides comprehensive niche graphene market reports, and our reports cover everything you need to know about these niche markets. The reports are now updated to July 2018.

Graphene batteries market report 3D cover

The Graphene Batteries Market Report:

  • The advantages using graphene batteries
  • The different ways graphene can be used in batteries
  • Various types of graphene materials
  • What's on the market today
  • Detailed specifications of some graphene-enhanced anode material
  • Personal contact details into most graphene developers

The report package provides a good introduction to the graphene battery - present and future. It includes a list of all graphene companies involved with batteries and gives detailed specifications of some graphene-enhanced anode materials and contact details into most graphene developers. Read more here!

Versarien provides updates on several energy storage R&D fronts

Versarien LogoVersarien, the advanced materials engineering group, has provided an update on its activities in relation to graphene-enhanced power storage devices like batteries and supercapacitors. The primary goal of incorporating graphene into these devices, Versarien says, is to significantly increase power storage capacity and reduce charging times.

Versarien has been working with WMG (Warwick Manufacturing Group) and their partner companies and scientists at the universities of Warwick and Cambridge to collaborate on the production of power storage devices such as batteries and supercapacitors using Versarien's proprietary Nanene graphene nano platelets. Significant advances have been made through incorporating the Company's high quality graphene into these devices and the Company looks forward to commercial products becoming available in due course.

The Graphene Catalog - find your graphene material here

First Graphene and Flinders University form a new company to commercialize VFD technology

First Graphene logo imageFirst Graphene is collaborating with Flinders University to launch 2D Fluidics - a company that will aim to commercialize the Vortex Fluidic Device (VFD). 2D Fluidics is 50% owned by FGR and 50% by Flinders University’s newly named Flinders Institute for NanoScale Science and Technology.

The VFD was invented by the Flinders Institute for NanoScale Science and Technology’s Professor Colin Raston and enables new approaches to producing a wide range of materials such as graphene and sliced carbon nanotubes. The key intellectual property used by 2D Fluidics comprises two patents around the production of carbon nanomaterials, assigned by Flinders University.

Rice University team creates 3D objects from graphene foam

Rice University scientists have developed a simple way to create conductive, 3D objects made of graphene foam. The resulting objects may offer new possibilities for energy storage and flexible electronic sensor applications, according to Rice chemist Prof. James Tour.

Rice team creates 3D objects from graphene foam image

The technique is an extension of groundbreaking work by the Tour lab that produced the first laser-induced graphene (LIG) in 2014 by heating inexpensive polyimide plastic sheets with a laser. The laser burns halfway through the plastic and turns the top into graphene that remains attached to the bottom half. LIG can be made in macroscale patterns at room temperature.

Progress in Malaysian order of trains with graphene-enhanced supercapacitors

In April 2017, The Ministry of Transport, national operator KTMB in Malaysia and China's CRRC Zhuzhou Locomotive signed a €180 million contract for the supply of electric trains with graphene-based supercapacitors. Now, reports indicate that the first of 13 Class 61 inter-regional diesel multiple-units for services along Malaysia’s east coast corridor have been largely completed at CRRC Zhuzhou’s plant in China.

Malaysian train with graphene-enhanced supercapacitor image

The first trainset is expected to be handed over to national operator KTMB by early July. After a period of testing, it is due to enter commercial service in October. The four-car, 1 000 mm gauge DMUs have a design speed of 140 km/h and are expected to operate at up to 120 km/h. They are reportedly being equipped with CRRC’s own design of graphene-based supercapacitor for storing braking energy and two MAN powerpacks.

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