The specific capacitance is equivalent to the amount of charge stored per unit gram of the active material and is denoted by Farad per gram (Fg –1 ). The Csp of any material is usually calculated from two electrochemical measurements, which are cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) profiles. a.
1. Specific capacitance (Csp) – This is the primary parameter that is essential to evaluate any supercapacitive material to determine its electrochemical charge storage properties. The specific capacitance is equivalent to the amount of charge stored per unit gram of the active material and is denoted by Farad per gram (Fg –1 ).
The specific capacitance of symmetrical capacitors at different scan rates is varied from 302.78 to 95.35 F/g. As compared with the earlier reports, the prepared supercapacitor attains an appreciable specific capacitance. The charge–discharge behavior of the fabricated symmetric capacitor (SC) device is also characterized by the cycle durability.
OR Specific Capacitance C = 2It/mV (Where I = [ (Ia + Ic)/2], Ia = anodic current, Ic = cathodic current, m= total weight of active materials of One electrode). if you want to calculate the capacitance based on one electrode, this factor 2 is introduced.
Super capacitors use electrostatic double-layer capacitance or electrochemical pseudocapacitance or a combination of both. The two electrodes form a series circuit of two individual capacitors C1 and C2. The total capacitance Ctotal is given by the formula C=C1C2/ (C1+C2). Supercapacitors may have either symmetric or asymmetric electrodes.
The charge and mass balance equation of a symmetric supercapacitor The amount of charge accumulated in a supercapacitor electrode is related to the Csp is given by the following equation [ 24, 25] (16.11) Q = C s p, material × m active material × Δ V Thus, (16.12) m active material = Q C s p, material × Δ V