Experts from the University of Surrey believe their dream of clean energy storage is a step closer after they unveiled their ground-breaking super-capacitor technology that is able to store and deliver electricity at high power rates, particularly for mobile applications.
In a paper published by the journal Energy and Environmental Materials, researchers from Surrey’s Advanced Technology Institute (ATI) revealed their new technology which has the potential to revolutionise energy use in electric vehicles and reduce renewable based energy loss in the national grid. The team also believe their technology can help push forward the advancement of wind, wave and solar energy by smoothing out the intermittent nature of the energy sources.
The ATI’s super-capacitor technology is based on a material called Polyaniline (PANI), which stores energy through a mechanism known as “pseudocapacitance.” This cheap polymer material is conductive and can be used as the electrode in a super-capacitor device. The electrode stores charge by trapping ions within the electrode. It does this by exchanging electrons with the ion, which “dopes” the material.
In their paper, the team detail how they developed a new three-layer composite using carbon nanotubes, PANI, and hydrothermal carbon that demonstrates remarkable rate-capability at high energy densities, independent of the power use.
Ash Stott, lead scientist on the project and Ph.D student from the University of Surrey, said: “The future of global energy will depend on consumers and industry using and generating energy more efficiently and super-capacitors have already been proven to be one of the leading technologies for intermittent storage as well as high-power delivery. Our work, has established a baseline for high energy devices that also operate at high power, effectively widening the range of potential applications.”
Professor Ravi Silva, Director of the ATI at the University of Surrey, said: “This highly ambitious and impactful work has the potential to change the way we all live our lives — and it might be what is needed to make the change for an efficient and fast charging solution of harvested energy from the environment. We see this having an impact in all sorts of industries — from all wearable technology to mobile Internet of Things applications that will launch the 5G revolution. The potential for our super-capacitor is limitless.”
A capacitor that can store a large amount of energy, typically 10 to 100 times more energy per unit mass or volume than the ordinary electrolytic capacitors is known as supercapacitor. These days it is getting more attention because of its faster and simpler charging, and faster delivery of charge feature. A supercapacitor is also known as ultracapacitor or double-layer electrolytic capacitor.
In a supercapacitor the combination of plates and the larger effective surface area enables to have greater capacitance and higher energy density. Unlike a battery, a supercapacitor has an unlimited life cycle, with little wear and tear on long-term use. Thus, it can be used in wireless charging with higher efficiency rate.
Supercapacitor should not be misunderstood with a replacement to battery. Batteries are used to store long-term energy. If, for example, the charge and discharge times are more than 60 seconds, use a battery; if shorter, then the supercapacitor becomes economical.
Supercapacitors are ideal when a quick charge is needed to fill a short-term power need; whereas batteries are chosen to provide long-term energy. Combining the two into a hybrid battery satisfies both needs and reduces battery stress, which reflects in a longer service life. Such batteries are being made available today in the lead acid family.
Comparing the super-capacitor with a battery has merits, but relying on similarities prevents a deeper understanding of this distinctive device. Here are unique differences between the battery and the supercapacitor.
The chemistry of a battery determines the operating voltage; charge and discharge are electrochemical reactions. In comparison, the capacitor is non-electrochemical and the maximum allowable voltage is determined by the type of dielectric material used as separator between the plates. The presence of electrolyte in some capacitors boosts the capacitance and this may cause confusion.
Since the supercapacitor is non-chemical, the voltage is free to rise until the dielectric fails. This is often in the form of a short circuit. Avoid going higher than the specified voltage.
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