rom harvesting energy to power plants, the use of power electronics is everywhere and there are few applications that do not require power. The power electronics industry has been very dynamic with many new technologies making the impossible now possible. In the unceasing quest to increase performance levels, reliability and sustainability, new components and technologies such as Wide Bandgap Semiconductors and Digital power management are receiving a lot of attention and coverage. However, hiding in the shadows is a component that is very important and alredy intrinsically involved in many evolving applications - The Supercapacitor.

Supercapacitors are being widely applied - although perhaps because they are seen as passive components with a low-tech connotation, they are seldom on centerstage. It is time to bring them back into the spotlight, so let's review the amazing story and technology behind the silent power of supercapacitors.

From Howard Becker to Elon Musk
In the early fifties when capacitors were made out of impregnated paper and mica, General Electric researched ways to increase their capacity to store and release higher energy levels and to be able to absorb voltage distortions in electronics especially in top secret military applications. Research was conducted by Howard I. Becker and his team who on 14th April 1954 filed a patent for a 'Low voltage electrolytic capacitor' using a porous carbon electrode. On 23rd July 1957 the US2800616A patent was granted, thus opening the road for further innovation. Becker's invention was the beginning of a race between laboratories to convert the invention into a component capable of being mass manufactured with higher performance levels. In 1958, Philips NV patented a process for the production of electrodes for electrolytic capacitors and the electrolytic capacitor was born.

Although the invention of the electrolytic capacitor was an important step forward for the electronics industry, the capacity was still not enough to store higher levels of energy such as is required to stabilize an electric network or to deliver extremely high energy levels as required by certain applications in the defense industry. It took another six years of research after Becker's patent for the Robert A. Rightmire an engineer at Standard Oil Company to be granted on the 29th of November 1966, the US3288641A patent for an 'Electrical energy storage apparatus'. It was described as: "An electrical energy storage device for storing energy in electrostatic condition as double layers of electron-ions and proton-ions at co-acting interfaces…"

The supercapacitor was born!

Interestingly, it then took another 10 years for the invention to become a market reality.

Because of their capacity to store and release high amounts of energy in a very short time period, Electrical Vehicle (EV) research on high performance supercapacitors intensified and the number of inventions and patents sky-rocketed. The foremost application in EVs was to store the energy generated when decelerating and braking in order to re-use that energy to power the engine when accelerating. The potential of the supercapacitor received heightened attention in March 2011 at the Cleantech Forum in San Francisco where regarding the future of electric vehicles Elon Musk said, "If I were to make a prediction, I'd think there's a good chance that it is not batteries, but super-capacitors that will power the future of EV." Just to remind ourselves, Musk originally came to California to study high-energy-density capacitor physics at Stanford. His speech started a lot of speculation about the potential of supercapacitors, with the perception that they would be the solution to mass energy storage, eventually replacing batteries. The reality is a bit different though, from the timing of Becker and Rightmire's original patents up to the present day, supercapacitor technology has progressed in a fair degree of 'behind the scenes' silence.

How does it work?
As we all remember from school, a capacitor consists of two metal plates or conductors separated by an insulator such as air or a film made of plastic or ceramic. During charging, electrons accumulate on one conductor and depart from the other. Using normal manufacturing practices a conventional capacitor's energy storage is limited by the laws of physics and that is where Robert A. Rightmire's invention opened new avenues for high energy storage.

When a voltage is applied to the positive plate, it attracts negative ions from the electrolyte, and when a voltage is applied to the negative plate, it attracts positive ions from the electrolyte. As a result, ion layers form on both sides of the plate in what is called a 'double layer' formation, resulting in the ions being stored near the surface of the carbon. This mechanism gives supercapacitors the ability to store and restore high energy within a very short time period.

Will supercapacitors supersede batteries and What's coming next?
Following Elon Musk's speech at Cleantech Forum 2011, there has been a lot of interest in supercapacitors and the potential offered by nanotechnologies is keeping hopes high that at some point in the future, supercapacitors might reach a point where they equal the performance of batteries.

Will that happen?
Find more in Part 2 of this article in the next edition of the PSMA newsletter.

Provided by Patrick Le Fèvre Chief Marketing and Communications Officer, Powerbox

Editor's note: This is the first in a 2-part series, watch for the second article in the First Quarter 2019 Issue of the PSMA Update.

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