What is a supercapacitor ?

SupercapTech.com is an information website on supercapacitors.

These electricity storage devices can be compared with batteries, but they can charge much faster and can survive hundreds of thousands more charge and discharge cycles. Supercapacitors have potential to revolutionize our daily lives.

On SupercapTech.com, we show the new supercapacitors marketed with their technical characteristics, the products equipped with ultracapacitors, technological breakthroughs and techniques used by laboratories to create supercapacitors with increasingly impressive capabilities.

With the ultra-fast charge and very long life ability, the supercapacitor should quickly establish itself as the great ideal battery for electronic devices, electric transportation and storage for the renewable energies.

Why supercapacitors didn't replace batteries yet ?

The last point that needs improvement to make supercapacitor as the ultimate battery is the energy density. That is the amount of energy that can be stored in a supercapacitor compared to its weight and size. Supercapacitors currently marketed have an energy density of 4 to 6 Watt-hours per kilogram. In June 2014, Maxwell Technologies innovated by completing its range with a supercapacitor reaching 7.7 Watt-hours per kilogram.

In July 2015, Skeleton Technologies did better with supercapacitors reaching an energy density of 9.6 Wh / kg. Such performance was previously reserved for very demanding customers which were able to pay the price. Indeed, these new generation of supercapacitors based on CDC (or curved graphene flakes) were previously reserved for the aerospace and military defense, as well as oil and gas exploration industry which is very interested in this more reliable storage device and safer to use than lithium-ion batteries.

Research is progressing fast in laboratories, and scientists have already succeeded in creating supercapacitors with an energy density of 155 Wh per kg when lithium-ion batteries reach 150 Wh per kg (Warning : supercapacitors created in laboratories are not all intended to be marketed because of difficulties to industrialise production development or because of construction costs).

Technically, what exactly is a supercapacitor ?

Technically, a supercapacitor is not a battery. It is a kind of super capacitor capable of storing a certain amount of electric charge. A capacitor is an elementary electronic component made with two electrodes (plates) separated by a polarizable insulating material (dielectric).

But unlike a capacitor, a supercapacitor have a double electric layer on each electrode-electrolyte interface (see No, a supercapacitor is not a capacitor). The presence of this electric double layer alters the characteristics and the behavior of a supercapacitor compared to a capacitor. In a supercapacitor, electrodes are designed to develop the largest possible area, thanks to microporous activated carbons and more recently through graphene. Thus, a supercapacitor can store 1 million times more electrical energy than a capacitor and can maintain its charge for a much longer time.

A supercapacitor is not only a "super" capacitor capable of storing more electrical energy. This is a special electricity storage device that have high potential for improvement. Note that supercapacitor is also called "ultracapacitor" or "EDLC".

A supercapacitor can store energy directly in an electrostatic field, that is completely different from the working of a battery which use some chemical reactions to store electricity. Electricity is stored or released much more quickly in ultracapacitors because of there is no electrochemical process. The supercapacitor can be recharged 10,000 times faster than conventional batteries and can provide extremely high power in a short lapse of time.

Concretely, the energy storage in a battery or a supercapacitor is due to their ability to transfer and store charged particles called ions. Both devices use an electrolyte : a mixture of positive and negative ions. In a battery, chemical reactions move ions of the electrolyte inward or outside the atomic structure of the material composing the electrode, causing a change in oxidation state of the material, depending on whether the battery is charged or discharged. On the other hand, in a supercapacitor, an electric field pulls the ions to move towards or away from the electrode surface without redox reaction. Because ions are only adsorb or desorb (attach or detach) from electrodes without any chemical reaction, a supercapacitor can be charged and discharged very quickly, again and again. But a battery stores charges by redox reaction in the volume of materials, allowing it to store a large amount of energy, while the supercapacitor stores ions only on surface of its electrodes.

The solution for increase the amount of energy storage in supercapacitor is simple : provide more electrode surface to allow larger amount of ions to be adsorbed on it (fixed by attraction). In commercial supercapacitors today, the electrode surface is covered with activated carbons, a material which is full of pores providing a surface for ions to house in them. But the energy storage is still weak. Laboratory supercapacitors created with graphene electrodes, carbon nanowires or manganese dioxide and using an electrolyte based on ionic liquid seem most promising, but many other materials are tested to develop supercapacitors with sometimes incredible performance.

From research to practical applications...

The development of nanotechnologies and the recent understanding of mechanisms used for storage energy in a supercapacitor now allow scientists to improve the characteristics of this great electronic component. From ultra-thin and flexible supercapacitor for mobile electronics to massive supercapacitor for storage of renewable energy and for powering public transportation, this technology will soon prevail in all areas.

The price of supercapacitors has been divided by 100 in 15 years and we can now see first electric buses, trains, trams or electric boats powered exclusively by supercapacitors.

When high density supercapacitors wil hit the market, it will be possible to recharge our mobile phone in seconds, and to recharge our electric car in less than 5 minutes. This can radically develop the electric vehicle market. The high-density supercapacitor will also be the most effective way to store electricity produced by renewable energy at home and in particular by photovoltaics which is rapidly growing.

With SupercapTech.com, follow step by step the growing of this technology which is going to revolutionize your everyday life and the electric mobility. This electricity storage device should be imposed in parallel with the other coming revolution that is the mass development of photovoltaic. What drastically change the energy paradigm and create a global geopolitical upheaval.