Pseudokapacitatiivset

Pseudokapacitatiivset refers to a phenomenon observed in certain electrochemical systems where a surface or material exhibits capacitive-like behavior that is not due to a true electrochemical double layer. Instead, this pseudocapacitance arises from fast, reversible faradaic reactions occurring at or near the electrode surface. These reactions involve charge transfer across the electrode-electrolyte interface, similar to battery-like processes, but they happen at very high rates, mimicking the charge storage mechanism of an electric double-layer capacitor (EDLC).

The key difference between true capacitive behavior and pseudocapacitance lies in the origin of charge storage. EDLCs store charge through the accumulation of ions at the interface, forming an electrical double layer. Pseudocapacitive materials, on the other hand, store charge through redox reactions, intercalation, or adsorption/desorption of ions onto or into the material. While these are faradaic processes, their kinetics are often much faster than bulk diffusion-limited reactions typical of batteries, leading to a steep voltage-current response characteristic of capacitors.

Common materials exhibiting pseudocapacitance include transition metal oxides and hydroxides (like RuO2, MnO2, Ni(OH)2), conducting polymers, and certain layered materials. The rate at which these reactions occur, and thus the pseudocapacitive performance, is highly dependent on factors such as material morphology, surface area, particle size, and electrolyte composition. Pseudocapacitance is a significant area of research in energy storage, particularly for supercapacitors, as it can significantly increase energy density compared to traditional EDLCs while maintaining good power density.