Current Function
Bound redox
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
Potential/mV
i pc
i pa
0
–100
–200
Diffusion redox
E pc
116
Electrochemical Supercapacitors for Energy Storage and Delivery
FIGURE 3.7
Cyclic voltammograms of pseudocapacitance for ferricyanide and ferrocyanide couple free
in solution (solid line), compared to ferrocyanide bound to a collector with PVP (dashed line).
(Source: Conway, B. E., V. Birss, and J. Wojtowicz. 1997. Journal of Power Sources, 66, 1–14. With
permission.)
on its electrochemical properties, strong reversibility, very high conductivity, and wide potential range of 1.4 V and high capacitance. Wide potential
is possible due to the three available redox reactions (Ru 2+ ↔Ru 3+ , Ru 3+ ↔Ru 4+ ,
and Ru 4+ ↔Ru 6+ ). Unfortunately, Ru is a noble metal and too expensive for ES
applications.
The attractiveness of cheap nickel oxide materials led to studies of different crystal and nano morphologies that offer improved performance
and reversibility via improvements to surface area. Table 3.2 illustrates the
variability possible for this pseudocapacitive material, highlighting the
importance of optimizing internal diffusion and conductivity by controlling morphology and choosing the correct crystal structure. This table also
Bound redox
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
Potential/mV
i pc
i pa
0
–100
–200
Diffusion redox
E pc
116
Electrochemical Supercapacitors for Energy Storage and Delivery
FIGURE 3.7
Cyclic voltammograms of pseudocapacitance for ferricyanide and ferrocyanide couple free
in solution (solid line), compared to ferrocyanide bound to a collector with PVP (dashed line).
(Source: Conway, B. E., V. Birss, and J. Wojtowicz. 1997. Journal of Power Sources, 66, 1–14. With
permission.)
on its electrochemical properties, strong reversibility, very high conductivity, and wide potential range of 1.4 V and high capacitance. Wide potential
is possible due to the three available redox reactions (Ru 2+ ↔Ru 3+ , Ru 3+ ↔Ru 4+ ,
and Ru 4+ ↔Ru 6+ ). Unfortunately, Ru is a noble metal and too expensive for ES
applications.
The attractiveness of cheap nickel oxide materials led to studies of different crystal and nano morphologies that offer improved performance
and reversibility via improvements to surface area. Table 3.2 illustrates the
variability possible for this pseudocapacitive material, highlighting the
importance of optimizing internal diffusion and conductivity by controlling morphology and choosing the correct crystal structure. This table also