The majority of the commercially available ultracapacitor is Electric Double-Layer Capacitor, or EDLC. An EDLC can be viewed as a set of two nonreactive porous carbon electrodes on current collectors, immersed in an electrolyte system with a voltage potential applied across the collectors.
In an EDLC cell, the applied potential on the positive electrode attracts the negative ions in the electrolyte, while the same potential at the negative electrode attracts the positive ions. A dielectric separator prevents the two electrodes from creating a short circuit. The amount of energy stored is very large compared to a traditional capacitor due to the enormous surface area that is available on the porous carbon electrodes.
Though EDLCs are considered electrochemical devices, no chemical reactions are involved in the energy storage mechanism. The energy storage mechanism is a physical phenomenon and is highly reversible; this gives EDLCs their extremely long cycle life. Since the rates of charge and discharge are dependent only upon the physical movement of ions, the ultracapacitor can store and release energy much faster (meaning more power) than a battery that relies on slower chemical reactions.
Nesscap Pseudocapacitor cell is a hybrid capacitor which is a combination of EDLC and high energy battery. This configuration provides quick energy release of an EDLC and the higher storage capacity of a battery in one package. In a pseudocapacitor cell, one of the two porous carbon electrodes is replaced with such materials as metal-doped carbons, conducting polymers, or metal oxides. This result in two different charge mechanisms at the electrodes: electric double layer form at the porous carbon electrode and a combination of faradaic and surface reactions occur at the high energy electrode. This combination produces a charge transfer behavior that is linearly dependent upon the applied voltage, and, as a result, the final device functions and behaves like a capacitor.
Nesscap's Pseudocapacitors typically have little less than double the energy of the EDLC products of similar physical dimensions at the cost of shorter cycle life and lower rate capabilities. For applications that does not require so much heavy-duty cycling, such as UPS or other power
backup applications, using Pseudocapacitors can be the optimal solution.