282
Electrochemical Supercapacitors for Energy Storage and Delivery
is reported. For a symmetrical cell, the 0.6 V input voltage is split between
the two electrodes charging from an internally defined open-circuit voltage
(centered on the voltage window).
In the pseudocapacitive case, the separate reactions create a stable region
around –0.2 V that likely defines the center voltage. CDC indicates that
the positive electrode will have a lower capacitance of 410 F.g –1 , while the
negative electrode will charge closer to 1110 F.g –1 . By considering the series
capacitance as discussed later in this chapter, the full cell capacitance will be
approximately 300 F.g –1 . This value is similar to the measured two-electrode
configuration capacitance of 360 F.g –1 . The PPy composite evaluated in the
same work exhibits a higher level of correlation with 196 F.g –1 for three-electrode estimation of full cell capacitance and 200 F.g –1 for the measured twoelectrode configuration [2].
7.3 Cyclic Voltammetry (CV)
Cyclic voltammetry (CV), a widely used potential-dynamic electrochemical
technique, can be employed to obtain qualitative and quantitative data about
surface and solution electrochemical reactions including electrochemical
kinetics, reaction reversibility, reaction mechanisms, electrocatalytical processes, and effects of electrode structures on these parameters. A potentiostat instrument such as the Solatron 1287 is normally used to control the
electrode potential. The CV measurement is normally conducted in a threeelectrode configuration or electrochemical cell containing a working electrode, counter electrode, and reference electrode, as illustrated in Figure 7.1.
However, with alternative configurations, CV measurements can also be performed using a two-electrode test cell. The electrolyte in the three-electrode
cell is normally an aqueous or non-aqueous liquid solution.
During CV measurement, the potential of the working or target electrode
in the system is measured against the reference electrode via linear scanning
back and forth between the specified upper and lower potential limits, as
shown in Figure 7.4. The slope of the linear (forward and back) lines is called
the potential (E) scan rate (ν):
ν =
dE
(7.1)
dt
where E is expressed in V or mV units and ν is in V.s –1 or mV.s -1 . In Figure 7.4,
the potential–time plot can be expressed as:
E = E i + νt when 0 ≤ t ≤ λ
(7.2)
Electrochemical Supercapacitors for Energy Storage and Delivery
is reported. For a symmetrical cell, the 0.6 V input voltage is split between
the two electrodes charging from an internally defined open-circuit voltage
(centered on the voltage window).
In the pseudocapacitive case, the separate reactions create a stable region
around –0.2 V that likely defines the center voltage. CDC indicates that
the positive electrode will have a lower capacitance of 410 F.g –1 , while the
negative electrode will charge closer to 1110 F.g –1 . By considering the series
capacitance as discussed later in this chapter, the full cell capacitance will be
approximately 300 F.g –1 . This value is similar to the measured two-electrode
configuration capacitance of 360 F.g –1 . The PPy composite evaluated in the
same work exhibits a higher level of correlation with 196 F.g –1 for three-electrode estimation of full cell capacitance and 200 F.g –1 for the measured twoelectrode configuration [2].
7.3 Cyclic Voltammetry (CV)
Cyclic voltammetry (CV), a widely used potential-dynamic electrochemical
technique, can be employed to obtain qualitative and quantitative data about
surface and solution electrochemical reactions including electrochemical
kinetics, reaction reversibility, reaction mechanisms, electrocatalytical processes, and effects of electrode structures on these parameters. A potentiostat instrument such as the Solatron 1287 is normally used to control the
electrode potential. The CV measurement is normally conducted in a threeelectrode configuration or electrochemical cell containing a working electrode, counter electrode, and reference electrode, as illustrated in Figure 7.1.
However, with alternative configurations, CV measurements can also be performed using a two-electrode test cell. The electrolyte in the three-electrode
cell is normally an aqueous or non-aqueous liquid solution.
During CV measurement, the potential of the working or target electrode
in the system is measured against the reference electrode via linear scanning
back and forth between the specified upper and lower potential limits, as
shown in Figure 7.4. The slope of the linear (forward and back) lines is called
the potential (E) scan rate (ν):
ν =
dE
(7.1)
dt
where E is expressed in V or mV units and ν is in V.s –1 or mV.s -1 . In Figure 7.4,
the potential–time plot can be expressed as:
E = E i + νt when 0 ≤ t ≤ λ
(7.2)