Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A
This journal is © The Royal Society of Chemistry 2013
Improved Supercapacitor Performance of MnO2–Graphene
Composites Constructed Using Supercritical Fluid and Wrapped by
Ionic Liquid
Electronic Supplementary Information
Ming-Tsung Lee1, Chen-Yen Fan1, Yi-Chen Wang1, Hui-Ying Li1,
Jeng-Kuei Chang1,2,3*, Chuan-Ming Tseng4
1
2
Institute of Materials Science and Engineering,
Department of Chemical and Materials Engineering,
3
Department of Mechanical Engineering,
National Central University, Taoyuan, Taiwan.
4
Institute of Physics, Academia Sinica, Taipei, Taiwan
Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A
This journal is © The Royal Society of Chemistry 2013
(a)
Mn3O4
-
(b)
Zone axis: [110]
Mn3O4
112
220
d211=2.5 Å
-
d103=2.8 Å
112
Fig. SI1. (a) Electron diffraction pattern and (b) high-resolution lattice image of a
Mn3O4 crystal found in the sample synthesized at a CO2 pressure of 6 MPa.
▼
Intensity
▼ MnCO3 ◆ MnO2
◆
▼
▼
◆
◆
◆
▼
▼
◆
▼
◆
▼
ii
◆
◆
20
◆
30
40
◆
50
60
i
70
Diffraction angle (degree)
80
Fig. SI2. X-ray diffraction patterns of samples synthesized using 12-MPa SCCO2 at
50 °C (curve i) and 70 °C (curve ii).
Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A
This journal is © The Royal Society of Chemistry 2013
16
Current density (A/g)
12
(a)
i
8
ii
4
0
-4
-8
-12
-16
0.0
0.2
0.4
0.6
0.8
1.0
Potential (V vs.Ag/AgCl)
Current density (A/g)
120
(b)
i
80
ii
40
0
-40
-80
-120
0.0
0.2
0.4
0.6
0.8
Potential (V vs. Ag/AgCl)
1.0
Fig. SI3. Cyclic voltammograms measured at (a) 50 mV/s and (b) 500 mV/s of
samples synthesized using 12-MPa SCCO2 at 50 °C (curves i) and 70 °C
(curves ii).
Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A
This journal is © The Royal Society of Chemistry 2013
Intensity
Intensity
(a) (b)
D
G
2D
1400 1600 1800 2000 2200 2400 2600 2800
1000 1200
Raman shift (cm-1)
(c) C–C
C=O
C–O
O–C=O π–π*
282 284 286 288 290 292 294 296
278 280
Binding energy (eV)
Fig. SI4. (a) Raman spectrum, (b) atomic force microscopy analysis, and (c) X-ray
photoelectron spectroscopy spectrum of prepared graphene. Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A
This journal is © The Royal Society of Chemistry 2013
▼ MnCO3 ◆ MnO2
◆
Intensity
◆
◆
iii
◆
◆
◆
ii
▼
20
▼
◆
▼
30
40
◆
◆
50
60
◆
i
70
80
Diffraction angle (degree)
Fig. SI5. X-ray diffraction patterns of SCCO2-derived MnO2/graphene (curve i),
air-derived MnO2/graphene (curve ii), and SCCO2-derived MnO2 (curve iii).
The synthesis time for the three samples was 3 hours.
Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A
This journal is © The Royal Society of Chemistry 2013
Current density (A/g)
16
(a)
i
8
ii
0
-8
-16
0.0
0.2
0.4
0.6
0.8
1.0
Potential (V. vs Ag/AgCl)
Current density (A/g)
120
(b)
i
80
ii
40
0
-40
-80
-120
0.0
0.2
0.4
0.6
0.8
Potential (V vs. Ag/AgCl)
1.0
Fig. SI6. Cyclic voltammograms measured at (a) 50 mV/s and (b) 500 mV/s of
SCCO2-derived MnO2/graphene electrodes with synthesis times of 0.5 hours
(curves i) and 3 hours (curves ii).
Current density (A/g)
Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A
This journal is © The Royal Society of Chemistry 2013
16
(a)
ii
8
i
0
-8
-16
0.0
0.2
0.4
0.6
0.8
1.0
Potential (V vs. Ag/AgCl)
Current density (A/g)
8.0
(b)
ii
4.0
i
0.0
-4.0
-8.0
0.0
0.2
0.4
0.6
0.8
Potential (V vs. Ag/AgCl)
1.0
Fig. SI7. Cyclic voltammograms of (a) plain MnO2 electrodes and (b) plain graphene
electrodes without (curves i) and with (curves ii) IL wrapping measured at a
potential scan rate of 50 mV/s.
Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A
This journal is © The Royal Society of Chemistry 2013
Potential (V vs. Ag/AgCl)
1.0
(a)
0.8
0.6
0.4
0.2
0.0
0
Potential (V vs. Ag/AgCl)
1.0
30
60
Time (seconds)
90
120
(b)
0.8
0.6
0.4
0.2
0.0
0
20
40
60
80
Time (seconds)
Potential (V vs. Ag/AgCl)
1.0
(c)
0.8
0.6
0.4
0.2
0.0
0
15
30
Time (seconds)
45
60
Fig. SI8. Galvanic charge–discharge curves of SCCO2-MnO2/graphene/IL measured
with a two-electrode configuration at applied current densities of (a) ±10
A/g, (b) ±15 A/g, and (c) ±20A/g.