Pseudokapasitanssi

Pseudokapasitanssi refers to a phenomenon observed in certain electrochemical systems where the measured capacitance appears larger than would be predicted by the physical dimensions of the electrical double layer alone. This apparent increase in capacitance is not due to a true increase in the geometric area or dielectric constant of the interface, but rather arises from specific faradaic processes that occur at or near the electrode surface.

These faradaic contributions involve charge transfer reactions, such as the adsorption or desorption of ions, redox reactions of surface species, or diffusion-controlled processes. When these processes are kinetically limited or occur within a narrow potential window, they can mimic the behavior of a capacitor, leading to a pseudocapacitive effect. This distinguishes pseudokapasitanssi from the purely electrostatic charging of the double layer, which is known as electrical double-layer capacitance (EDLC).

The magnitude of pseudokapasitanssi is highly dependent on the electrode material, the electrolyte composition, and the applied potential. It is a crucial factor in the performance of supercapacitors and other electrochemical energy storage devices, as it can significantly enhance the overall charge storage capacity. Understanding and controlling pseudokapasitansiittii is therefore essential for optimizing the design and efficiency of these devices. Techniques like cyclic voltammetry and electrochemical impedance spectroscopy are commonly used to differentiate and quantify pseudokapasitansiittii from EDLC.