Environmental Engineering Reference
In-Depth Information
on large trucks and hybrid vehicles having electric-only range capability, the
asymmetrical super-capacitor, or pseudo-battery, has the capability of very high
pulse power and somewhat more energy than an ultra-capacitor. A 60 kJ super-
capacitor, charged from a small 12 V lawn tractor battery, was demonstrated to
crank a 15 L over the road truck diesel engine for 15 s, several consecutive times
before its voltage was too low [21]. This testing was done even with the cold
capacitor, and it outperformed even a parallel connection of Group 31 lead-acid
modules. When super-capacitors are combined with batteries, such as those
described in References 22 and 23, it is common to use energy storage capacity in
the range 30-100 kJ. Combined with a 12.6 V lead-acid battery, this means a
super-capacitor of 378-1,260 F would be required. A typical super-capacitor
module would have one-half the volume of a Group 31 Class A truck battery.
The super-capacitor structure and chemistry is shown in Figure 10.25. Super-
capacitors consist of one polarizable electrode, carbon, and one Faradic electrode
made of nickel
oxyhydroxide (NiO(OH)) in a potassium hydroxide aqueous
solution.
KOH solution
Figure 10.25 Electrochemical capacitor or super-capacitor
As an illustration of production super-capacitors, or pseudo-batteries,
one manufacturer, ESMA, located in Russia produces these cells in modules for
automotive applications. A 14 V super-capacitor module can deliver very sub-
stantial peak power. Characteristics of two ESMA production modules are listed in
Table 10.4
Table 10.4 Electrochemical capacitor parameters
ESMA
capacitor
type
Voltage
range at
given energy
Peak
power
(kW)
Energy
(kJ)
Resistance,
R
i
,at25
C
(m
W
)
Resistance,
R
i
,at
30
C
(m
W
)
10EC1024
14.5 V
!
4 V
8.7
30
6
9
20EC402
14.5 V
!
4 V
35
90
2
3
