Stabalising Supercapacitors

Capacitors are often just imagined as two metal plates with a potential difference forced across them by a battery. Practically, there are many different types of capacitor, one of those being the electrolyte capacitor. This is designed from a sheet of metal that has a thin layer of oxide covering it which then is submerged in an electrolyte. The oxidise layer acts as the dielectric and since it is very thin and the metal plate can be entwined to have a large surface area when submerged the capacitance of these capacitors is considerably greater.

The ultimate type of capacitor, however, is called an electrochemical capacitor or more commonly a supercapacitor. These capacitors are made of both an anode and a cathode in an electrolyte. The positive plate absorbs the negative ions and the negative plate does the inverse. Normally each plate gets covered in two layers; for instance the positive plate gets coated in negative ions which then attract a balancing layer of positive ions. Both these layers (and occasionally more) form and act as a very efficient method of storing electrical energy.

A paper recently released has looked at the operation of super capacitors when put under extreme accelerations. Currently supercapacitors are used on cars, trains and busses where they can be used to aid regenerative braking or in machinery that is used to ft or push heavy weights as supercapacitors can provide burst of energy output. Stability is a key issue so understanding how supercapacitors react in large impacts is very important. It was found that if the acceleration is too great the electrolyte within the capacitor is forced to flow and circulate meaning that the dominant ion concentrations on each side are reduced. Since these ions are a primary part of the capacitance a reduction in these causes the capacitance and as a result the voltage to fluctuate during and for a time after the impact. A simple solution is convert to one of the newly developed solid electrolyte but these have yet to produce the same quality of capacitor as their liquid counterparts.


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