Specific double layer capacitance

The Mass of the Electrode m, the BET Surface AreaABET, the Total Pore Volume Vtot, the Average Pore Diameter Z)ave, the Size of the Microcrystallite La (Parallel to the Basal Plane), Lc (Parallel to the Edge Plane), the Ratio of LJL the CPE Exponent a and the Specific Double-Layer Capacitance Cd for Carbon Specimens A, B and C. Reprinted from Ref.17, Copyright (2006), with... 

Specimen Mass of the electrode, m (mg) BET surface area, Abet (mV) Total pore volume, Ktot (cm3 g1) Average pore diameter, Z5ave (nm) U (nm) u (nm) /- CPE exponent a /- Specific double-layer capacitance, Cd (Fm-2)... 

Cd Specific double-layer capacitance per unit area... 

It would be interesting to explore the proton-transfer (i.e., pH) dependence of the above electron transfer process. In the already mentioned study by Hsieh and Teng [11] (see Equations 5.1 through 5.3, Section 5.1), presumably Reaction 5.2, >CxO + H = >CxO//II —described as specific adsorption basically induced by ion-dipole attraction —was proposed to be responsible for the observed excess specific double layer capacitance due to the local changes of electronic charge density the invoked changes were not discussed in any detail, however. 

Specific double-layer capacitance Cdi is given by Gouy-Chapman-Stem (GCS) model [13-14] as follows ... 

Using knowledge of the particle area S, the charge transfer resistance, expressed as the ohmic parameter Ra (O), can be used to obtain the specific charge resistance Ret [Om ] as Ra = Rl, S. Correspondingly, (Farad) can be transformed into the specific double-layer capacitance Cat (Farad/m ) as Cji = C S. The combined ionic and electronic resistance of mesoporous material R (f2) is given by pdIA where p (Qm) is the specific resistance of the active material (sum of ionic and electronic resistances), A is the geometric surface area of the electrode (m ), and d is the thickness of the layer of active material (m). 

Since such surface redox reactions usually involve Faradaic charge transfer, the specific pseudocapacitances that can be manifested are some five to ten times larger than the specific double-layer capacitance (always present and significant at aU electrode interfaces) at the same electrode. Hence such pseudocapacitor systems are of importance for practical development as has been the case with RUO2, but mainly for military applications owing to the high cost of that material. 

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