Pseudocapacitors mechanism

Depending on the charge storage mechanism, one must distinguish between the electrical doublelayer capacitors (EDLC) and the pseudocapacitors. The principles and properties of both types of supercapacitors will be further described. 

Typically, a supercapacitor is composed of two electrodes dipped in an electrolyte solution with a suitable separator. It is generally accepted that the energy storage mechanism of supercapacitors can be classified into electrical double layer capacitors (EDLCs) and pseudocapacitors (Fig. 6.1A) (Jost et al., 2014). In EDLCs, the charge storage is based on a reversible ion adsorption from an electrolyte onto electrodes with high specific surface areas to form a double layer structure. The capacitance comes from the pure electrostatic... 

In this chapter, in order to make Mn02 more attractive for pseudocapacitor electrode materials, Mn02 was coated spontaneously on CNTs by the simple immersion of the CNTs into a KMn04 aqueous solution. The synthesis mechanism of the heterogeneous nucleation of Mn02 on the CNTs was investigated by in situ monitoring of the solution chemistry. 

At the same time, a fundamental understanding of supercapacitor design, operation, performance, and component optimization led to improvements of supercapacitor performance, particularly increasing their energy density. To further increase energy density, more advanced supercapacitors called pseudocapacitors, in which the electroactive materials are composited with carbon particles to form composite electrode materials, were developed. The electrochemical reaction of the electroactive material in a pseudocapacitor takes place at the interface between the electrode and electrolyte via adsorption, intercalation, or reduction-oxidation (redox) mechanisms. In this way, the capacitance of the electrode and the energy density can be increased significantly. 

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