Electrochemical supercapacitors are a type of supercapacitors in which energy is stored with the participation of reversible redox electrochemical processes (Faraday processes) in the surface layer of electrode material.
Content
General information
In charge electrochemical supercapacitors, redox electrochemical reactions occur in thin adsorption mono- and polymolecular films at electrode- electrolyte boundaries. When discharged, these same reactions go in the opposite direction. Thus, in electrochemical supercapacitors, energy is accumulated in the form of the internal energy of surface compounds at the electrode – electrolyte interface. The characteristics of such energy storage devices to a large extent depend on the properties of the electrodes used in them and their design. The main difference between electrochemical supercapacitors and batteries is that electrochemical processes occur exclusively on the surface of the electrode, which leads to a higher rate of electrochemical processes due to the absence of diffusion difficulties.
Distinctive features
Compared to traditional supercapacitors (ionistors), the most serious drawback of electrochemical capacitors is the lower resistance of electrode materials to chemical and electrochemical degradation. This leads to a reduction in the maximum number of charge-discharge cycles to several thousand or tens of thousands, depending on the type of electrode material used.
The main advantage of electrochemical capacitors compared to analogs is their potentially higher electrical capacitance with comparable power. The specific electric capacity of the most advanced electrodes used in ionistors usually does not exceed 300-400 F / g, while for modern electrodes based on ruthenium oxides and hydroxides, the capacity of 600-700 F / g is not limiting. Other known electrode materials for electrochemical supercapacitors are nanocrystalline oxides and hydroxides of nickel and manganese .
Modern electrochemical capacitors often have an asymmetric design, in which energy is accumulated on one electrode in a double electric layer , and on the other due to the occurrence of Faraday processes. Thus, the positive aspects of supercapacitors and electrochemical supercapacitors are used. Electrochemical capacitors of this type are currently the most promising for further improvement.
See also
- Chemotronic