Search results
Results From The WOW.Com Content Network
In electrochemistry, faradaic impedance [1] [2] is the resistance and capacitance acting jointly at the surface of an electrode of an electrochemical cell.The cell may be operating as either a galvanic cell generating an electric current or inversely as an electrolytic cell using an electric current to drive a chemical reaction.
Randles circuit schematic. In electrochemistry, a Randles circuit is an equivalent electrical circuit that consists of an active electrolyte resistance R S in series with the parallel combination of the double-layer capacitance C dl and an impedance (Z w) of a faradaic reaction.
Faraday discovered that when the same amount of electric current is passed through different electrolytes connected in series, the masses of the substances deposited or liberated at the electrodes are directly proportional to their respective chemical equivalent/equivalent weight (E). [3]
Faradaic efficiency of a cell design is usually measured through bulk electrolysis where a known quantity of reagent is stoichiometrically converted to product, as measured by the current passed. This result is then compared to the observed quantity of product measured through another analytical method.
Charge transfer coefficient, and symmetry factor (symbols α and β, respectively) are two related parameters used in description of the kinetics of electrochemical reactions. They appear in the Butler–Volmer equation and related expressions. The symmetry factor and the charge transfer coefficient are dimensionless. [1]
This technique measures the impedance of a system over a range of frequencies, and therefore the frequency response of the system, including the energy storage and dissipation properties, is revealed. Often, data obtained by electrochemical impedance spectroscopy (EIS) is expressed graphically in a Bode plot or a Nyquist plot.
Pseudocapacitance is the electrochemical storage of electricity in an electrochemical capacitor that occurs due to faradaic charge transfer originating from a very fast sequence of reversible faradaic redox, electrosorption or intercalation processes on the surface of suitable electrodes.
The upper graph shows the current density as function of the overpotential η . The anodic and cathodic current densities are shown as j a and j c, respectively for α=α a =α c =0.5 and j 0 =1mAcm −2 (close to values for platinum and palladium).