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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

Haydale's revenues increase 90% in H1 FY2016, updates on various graphene projects

Mar 23, 2017

Haydale logoUK-based Haydale announced its unaudited results for the six months ended 31 December 2016, or H1 FY2016. Total income was £1.5 million (up 90% from H1 2015) and the loss was £2.4 million (up from £1.9 million in H1 2015).

Haydale also provided some interesting update. The company signed a joint development agreement with Hunsman in Novermber 2016, and Haydale now says that Huntsman announced strong initial test results from Haydale's graphene enhanced Araldite resins in thermal management. Haydale's Thailand subsidiary also announced two new small contacts - one from the Thai Ministry of Energy for a printed hybrid functionalized graphene electrode in a supercapacitor and another from IRPC, a leading Thai petrochemical chemical processor.

Skeleton Technologies launches graphene-based engine start supercapacitor

Mar 19, 2017

Skeleton Technologies, developer and manufacturer of high energy and power density supercapacitors, has announced launching a new graphene-based engine start module to help power heavy industry vehicles in extreme conditions. Called SkelStart Engine Start Module 2.0, it is available in 24V and 12V versions and is based on the graphene-based SkelCap supercapacitors, which Skeleton says provide the highest power and energy density on the market.

Skeleton's new graphene-based supercapacitor image

The new module’s casing is made of non-flammable material that is resistant to vibration and shock, and is a stud terminal device in BCI Group 31 size. Skeleton states that “SkelStart Engine Start modules are designed to provide reliable engine starting in even the harshest conditions, as well as reduced ongoing costs on maintenance and replacement. Businesses can therefore expect their equipment to work cost effectively year-round, affording them peace of mind.”

Graphene Investment Guide

Graphene-Info's Batteries, Supercapacitors, GO, Lighting, Displays and Graphene Investments Market Reports updated to March 2017

Mar 06, 2017

Today we published a new version 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 March 2017.

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!

Skeleton Technologies receives a €15 million loan for graphene-based supercapacitors development

Feb 12, 2017

Skeleton Technologies logoSkeleton Technologies, developer and manufacturer of high energy and power density supercapacitors, has received €15 million in a loan from the European Investment Bank (EIB), under the European Fund for Strategic Investments (EFSI).

This funding is meant to allow the company to finance the R&D for the further development of its products and systems. Skeleton will use part of the money to invest in an electrode mass-production facility in Dresden, Germany, according to the statement. The loan is stated to be based on company performance and doesn’t dilute the holdings of Skeleton’s founders, according to the EIB.

Grafoid unveils a cost-effective graphene coating called GrafeneX

Feb 01, 2017

Grafoid logoGrafoid, a leading graphene R&D and investment company, announced its entry into the global industrial coatings market with the introduction of its patent pending GrafeneX graphene coatings technology. Grafoid describes the GrafeneX technologies as a cost-effective way of laying down graphene coatings on large surface areas.

GrafeneX is a novel technology that creates a platform for the deposition of graphene and chemically functionalized graphene coatings. This process provides Grafoid with the capability to apply its diverse graphene-based coatings to many different types of material substrates with controllable levels of surface coverage, thickness etc. to meet precise end user requirements.