161
GO
Reduced GO
Parent graphite
10
4
0.1 nm
10
–3
10
–4
Conductivity σ
c , (S/m)
10
3
10
2
10
1
10
–5
0.0
0.1
0.4
0.5
0.6
0.7
0.8
(a)
Volum
(b)
e Fraction φ
Components and Materials for Electrochemical Supercapacitors
FIGURE 4.15
(a) STM image of atomic lattice structure of graphene sheet showing long range crystal order
and hexagonal ring structure. (Source: Rao, C. N. R. et al. 2009. Angewandte Chemie, 48, 7752–7777.
With permission.) (b) Comparison of conductivity of chemically oxidized and reduced graphite materials with its conductive graphite parent. (Source: Stankovich, S. et al. 2007. Carbon, 45,
1558–1565. With permission.)
To test device performance, interdigitated electrodes were printed by electrophoretic deposition onto a gold-coated glass wafer to compare AC against
OLC [60]. Electrophoresis occurred when charged particles moved predictably in solution based on an applied electrical force (12 mV zeta potential for
OLC). To stabilize the carbon materials, Mg+ ions were added to solution and
acted as a binder. The resulting electrodes were tested by cyclic voltammetry (Figure 4.15b). At high scan rates, the OLC-based electrode outperformed
AC because the ionic delay in the unordered carbon could reduce AC performance as average power was increased [60]. Further, the electrophoretic
deposition technique allows the patterned application of EDLC materials for
integrated circuitry.
4.2.8.5 Graphene
Graphene is a new advanced carbon material with unique morphology
that distinguishes it from other materials in the EDLC market. Graphite
is a highly ordered carbon structure consisting of many tightly stacked
sheets that exhibit angstrom level interspacing due to strong π-π bonding
between the basal lattice planes of the graphene. A graphene sheet consists
of many carbon atoms arranged into a large two-dimensional crystal lattice
(Figure 4.15a). When separated into fewer layers through the application of
some physical or chemical energy (single- or few-layer graphene), the material takes on very different properties from its bulk graphite state [61].
GO
Reduced GO
Parent graphite
10
4
0.1 nm
10
–3
10
–4
Conductivity σ
c , (S/m)
10
3
10
2
10
1
10
–5
0.0
0.1
0.4
0.5
0.6
0.7
0.8
(a)
Volum
(b)
e Fraction φ
Components and Materials for Electrochemical Supercapacitors
FIGURE 4.15
(a) STM image of atomic lattice structure of graphene sheet showing long range crystal order
and hexagonal ring structure. (Source: Rao, C. N. R. et al. 2009. Angewandte Chemie, 48, 7752–7777.
With permission.) (b) Comparison of conductivity of chemically oxidized and reduced graphite materials with its conductive graphite parent. (Source: Stankovich, S. et al. 2007. Carbon, 45,
1558–1565. With permission.)
To test device performance, interdigitated electrodes were printed by electrophoretic deposition onto a gold-coated glass wafer to compare AC against
OLC [60]. Electrophoresis occurred when charged particles moved predictably in solution based on an applied electrical force (12 mV zeta potential for
OLC). To stabilize the carbon materials, Mg+ ions were added to solution and
acted as a binder. The resulting electrodes were tested by cyclic voltammetry (Figure 4.15b). At high scan rates, the OLC-based electrode outperformed
AC because the ionic delay in the unordered carbon could reduce AC performance as average power was increased [60]. Further, the electrophoretic
deposition technique allows the patterned application of EDLC materials for
integrated circuitry.
4.2.8.5 Graphene
Graphene is a new advanced carbon material with unique morphology
that distinguishes it from other materials in the EDLC market. Graphite
is a highly ordered carbon structure consisting of many tightly stacked
sheets that exhibit angstrom level interspacing due to strong π-π bonding
between the basal lattice planes of the graphene. A graphene sheet consists
of many carbon atoms arranged into a large two-dimensional crystal lattice
(Figure 4.15a). When separated into fewer layers through the application of
some physical or chemical energy (single- or few-layer graphene), the material takes on very different properties from its bulk graphite state [61].