Supplementary Information for
Mesoporous NiO crystals with dominantly exposed {110} reactive facets for
ultrafast lithium storage
Dawei Su,a Mike Fordb, and Guoxiu Wanga,*
a
Centre for Clean Energy Technology, School of Chemistry and Forensic Science, University of
Technology, Sydney, Broadway, Sydney, NSW 2007, Australia
b
Materials and Technology for Energy Efficiency, School of Physics and Advanced Materials,
University of Technology, Sydney, Broadway, Sydney, NSW 2007, Australia
Corresponding author: Guoxiu Wang, Fax: (+61) 2 95141460, E-mail: Guoxiu.Wang@uts.edu.au
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Table S1. The calculation on the volume change of NiO electrode
NiO
Li2O
Ni
Volume of unit cell / Å3 18.10708 24.4925 10.94078
Volume change
95.69%
NiO + 2Li+ + 2e- ↔ Li2O + Ni
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Intensity (a.u.)
Calculated
Observed
Difference
Bragg deflection lines
10
20
30
40
50
60
70
80
90
2 (degree)
Supplementary Figure S1. Rietveld refinement pattern of X-ray diffraction data for Ni(OH)2 crystals.
The observed and calculated intensity are represented by red solid circle and blue solid line,
respectively. The bottom purple line shows the fitting residual difference. Bragg positions are
represented as light green tick.
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Calculation for the surface area:
The ratio of the exposed {111} facets to total surface area for Ni(OH)2 crystals can be calculated
from the following equation:
(1)
Where the {111}, {110}, {011}, and {101} facets and the length of AB, AG can be seen in Figure 1
b and c (also presented in Figure S2)
Supplementary Figure S2. The simulated geometrical model of the faceted Ni(OH)2 nanoplatelet
indexed with the different enclosed facets.
Indeed, there are very dense mesopores dispersed in NiO nanoplatelets. However, the total pore area
was calculated to be 61.26 m2 g-1 from the integrated Barret–Joyner–Halenda (BJH) adsorption
measurement. It should be noted that the specific surface area of NiO nanocrystals is 197.5 m2 g-1. If
the pore area is substracted from the total surface area, 68.98 % of the surface area is contributed by
the enclosed facets of the nanoplatelets, in which 95.64 % is {110} facets (deduced from the ratio of
the exposed {111} facets to the total surface area in Ni(OH)2 precursor). Therefore, the {110} crystal
planes occupy about 66% of the total surface area after counting the pore area. The {110} crystal
plane is a dominant facet in the as-prepared mesoporous NiO nanoplatelets.
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Supplementary Figure S3. Low magnification TEM image of mesoporous NiO crystals.
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Supplementary Scheme S1. Schematic illustration of the formation mechanism of faceted Ni(OH)2
single crystal and mesoporous faceted NiO crystals.
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Supplementary Scheme S2. The schematic illustration of the conversion from the hexagonal
Ni(OH)2 nanoplatelets to NiO nanoplatelets. The crystal mismatch between Ni(OH)2 and NiO is
small, based on the calculations on the crystal planes of (10 ), (0 1), and (1 0) in Ni(OH)2 and
(1 1), (1
), and (002) in NiO.
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-0.2
0.0
Current (mA)
0.2
10
th
2
nd
0.4
+
-
NiO+2Li +2e ->Ni+Li2O
0.6
0.8
1
st
1.0
1.2
1.4
SEI
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Potential (V)
Supplementary Figure S4. The first ten cycles CV curves of the mesoporous NiO crystals as anode
for lithium ion cell.
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Supplementary Figure S5. (a) The unit cell of Ni(OH)2 crystal, and side views of relaxed (b) {100},
(c) {111}, (d) {110}, (e) {112}, (f) {113}, (g) {101}, and (h) {121} crystal planes of Ni(OH)2
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Table S2. The calculated surface energies of Ni(OH)2.
surface
d-spacing, dhkl/Å
Surface energy / J m-2
100
3.088
1.674
110
5.863
1.176
111
4.894
0.952
112
5.349
0.955
113
5.036
1.279
121
7.336
1.253
101
6.444
1.072
211
7.336
1.421
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Supplementary Figure S6. (a) The unit cell of NiO crystal, and side views of relaxed (b) {113}, (c)
{100}, (d) {110}, and (e) {101} crystal planes of NiO.
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Table S3. The calculated surface energies of NiO
Surface
d-spacing, dhkl/Å
Surface energy / J m-2
100
1.311
0.958
110
1.683
1.476
113
1.254
1.264
101
1.38
1.482
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Supplementary Figure S7. SEM images of NiO electrodes taken from fully charged state at (a) 0.5 C
current rate after 100 cycles, (b) 10 C current rate after 1000 cycles, and (c) 40 C current rate after
1000 cycles.
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