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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.

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).

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

Skeleton Technologies and Flying Whales collaborate to develop large capacity aircraft with graphene-based supercapacitors

Jul 04, 2016

A new European partnership will aim to ensure that graphene supercapacitor technology powers the next generation of large, heavy-lift airships for industrial applications in China and France. Skeleton Technologies will join French firm Flying Whales’ programme to build a 60-ton Large Capacity Airship, or LCA60T, for the global transport market.

Flying Whales LCA60T photo

Skeleton Technologies will join the programme to help design and build hybrid propulsion for the LCA60T’s electric power systems. Average operational power is expected to be approximately 1.5 MW with the company’s graphene-based supercapacitors assisting to cover the additional 2 MW peaks for hovering, lifting and stabilization in reasonable and turbulent environments.

Haydale to become a collaborating member of the NGI

Jun 28, 2016

Haydale logoThe National Graphene Institute (NGI) recently signed a collaborative partnership with Haydale to accelerate the commercialization of applications. Haydale has been working closely with the NGI, and has now entered into a formal partnership which aims to leverage each party’s particular expertise in order to seek opportunities to develop and commercialize graphene products and applications.

This collaboration will likely see the NGI utilizing the Haydale patented process incorporated in its R&D plasma reactor for research into the functionalization of graphene and other nanomaterials. It will also look into the use, process and identification of nanomaterials to enhance performance in composites, sensors, printable inks, supercapacitators, rubbers and elastomers.

Graphene for the Display and Lighting Industries

A new Graphene-Info market report, Graphene for Supercapacitors

Jun 28, 2016

We're happy to announce a new market report, Graphene for Supercapacitors. This report, brought to you by the world's leading graphene experts, is a comprehensive guide to graphene technologies for the supercapacitor market. Graphene is an exciting material that promises to revolutionize entire industries - and it has a bright future in energy storage applications in general and in supercapacitors specifically.

graphene supercapacitors - report cover

Reading this report, you'll learn all about:

  • The advantages of using graphene in supercapacitors
  • Various types of graphene materials
  • Market insights and forecasts
  • What's on the market today

Other topics include:

  • A list of all graphene companies involved with supercapacitors
  • Prominent research activity in this field
  • Free updates for a year

New method doubles performance of 3D printed supercapacitors

Jun 19, 2016

Researchers from Lawrence Livermore National Laboratory (LLNL) and UC Santa Cruz (UCSC) have designed a technique that could double the performance of 3D printed graphene-based supercapacitors. The new technique involves sandwiching lithium ion and perchlorate ion between layers of graphene in aerogel electrodes—a process which greatly improves the capacity of the electrodes while maintaining the high rate capability of the devices.

Scientists double performance of 3D printed graphene aerogel supercapacitors

The 3D printing process used by the researchers to build the supercapacitors is a form of direct ink writing, consisting of two ion-intercalation steps before the hydrolysis of perchlorate ion intercalation compounds. According to the team “this two-step electrochemical process increases the surface area of graphene-based materials for charge storage, as well as the number of pseudo-capacitive sites that contribute additional storage capacity”.

Lomiko's Graphene ESD announces completion of supercapacitors project

Jun 01, 2016

Graphene ESD has announced the successful completion of its development project, undertaken jointly with the Research Foundation of Stony Brook University (SBU), that explored a novel method for assembly of high-voltage supercapacitor units.

Graphene ESD's supercapacitors image

The team assembled and tested a 10 V supercapacitor energy storage unit, thus proving feasibility of the high-voltage design. This development opens the door for new low-cost energy storage products. Currently, GESD is working on scale-up of the technology and an in-field evaluation of the energy storage unit.