Supercapacitor energy storage mechanism

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... 

The origin of the difference in the performances between batteries and supercapacitors lies in their energy storage mechanisms. In batteries, it occurs via chemical redox reactions occuring in the bulk of a material. The power limitations are due to the slow reaction kinetics and mass transport. In particular, Li" ions need to migrate into solid-state electrodes with relatively low ionic conductivities. On the contrary, supercapacitors are based on the physical adsorption of the ions from the electrolyte on the surface of the electrodes. The lower specific energy comes from the fact that only the surface of the material is used, but... 

Keywords Supercapacitors Charge storage mechanisms Conducting polymers Carbons Nanocomposites Energy storage... 

In recent years there has been increasing interest in the power capacitors, ultracapacitors or supercapacitors based on electrochemical systems. These include electric double layer capacitor (EDLC) types based on carbon electrodes with suitable electrolyte systems, and electrochemical capacitors with pseudocapacitance (Conway, 1991,1995). Several types of capacitors are classihed in Table 1.8 according to their energy storage mechanisms. 

Roldan, S., M. Granda, R. Menendez, R. Santamarfa, andC. Blanco. 2011. Mechanisms of energy storage in carbon-based supercapacitors modified with a quinoid redox-active electrolyte. Journal of Physical Chemistry C 115 17606-17611. 

Depending on the charge storage mechanism, supercapacitors can be classified into two types electrical double layer capacitors (EDLC) and pseudocapadtors [108]. EDLCs store and release energy based on the accumulation of charges at the interface between a porous electrode, typicalty a carbonaceous material with high surface area, and the electrotyte. In pseudocapadtors, the mechanisms rely on fast and reversible Faradaic redox reactions at the surface and/or in the bulk. 

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