Supplementary material
Antimony and antimony oxide@graphene oxide obtained by the peroxide route as anodes
for lithium-ion batteries
Denis Y.W. Yu a,b,c, Sudip K. Batabyal a, Jenny Gun d, Sergey Sladkevich d, Alexey A.
Mikhaylov d,e, Alexander G. Medvedev d,e, Vladimir M. Novotortsev e, Ovadia Lev d,f,* , Petr V.
Prikhodchenko e
I. Experimental details
Synthesis:
Preparation of hydroxoantimonate precursor solution: Preparation of hydroxoantimonate
precursor solution was described in our previous article (Prikhodchenko et al., 2012). Briefly, 10
mL of SbCl5 (0.078 mol) was dissolved in a few mL of deionized water (DIW) and neutralized
with ammonia until pH 7. The precipitate was washed several times with DIW and dissolved in
28.5 mL of 25% aqueous tetramethylammonium hydroxide (0.078 mol) under moderate heating.
After complete dissolution, DIW was added to achieve 1.4 M antimony concentration.
Preparation of graphene oxide. GO was synthesized from exfoliated graphite by a modified
Hummers method (Zhou et al., 2009) and a detailed protocol is described in our previous articles
(Prikhodchenko et al., 2012; Sladkevich et al., 2012a, 2012b). First, exfoliated graphite powder
(Modestov et al., 1997) (1 g) was added to a solution of K2S2O8 (1.67 g) and P2O5 (1.67 g) in 8
mL concentrated H2SO4. The mixture was kept at 80 °C for 4.5 h on a hot plate. After the
mixture was cooled to room temperature, it was diluted with 0.35 L of deionized water (DIW)
and filtered. Then the preoxidized material was washed with DIW and dried at 60-70°C
overnight. Next, preoxidized carbon was redispersed in 40 mL of concentrated H2SO4 with the
mixture kept in an ice bath. Subsequently, 5 g of potassium permanganate were added gradually
under constant stirring to avoid overheating. The mixture was stirred at 35 °C for 2 h and then
slowly diluted with 80 mL of DIW upon cooling in the ice bath. The mixture was stirred for an
additional 2 h and then 250 mL more DIW were added, followed by the addition of 6 mL of 30%
H2O2 to react with the excess of permanganate. The color of the solution changed to yellow after
addition of the peroxide. The oxidized product was washed with 300 mL of DIW and by dialysis
to remove the acid. A dispersion of GO in DIW was prepared by ultrasound bath treatment for 2
h. Aqueous GO dispersions were stable for at least a few months.
Preparation of GO-SbV. Typically, 2.8 g of aqueous GO dispersion (2% wt.) were dispersed in
15 mL of hydrogen peroxide (30%) by sonication. Then 0.7 mL of hydroxoantimonate solution
(1.4 M) was added. Precipitation of peroxoantimonate onto the GO surface was accomplished by
addition of 60-70 mL ethanol-diethyl ether mixture (1:1). The coated GO was washed with the
ethanol-ether solution and dried under vacuum at room temperature. The peroxoantimonate
coated GO was stored in a refrigerator.
Preparation of GO-Sb-80, rGO-Sb-300 and rGO-Sb-650. Heat treatment of the GO-SbV powder
was carried out in a tube furnace at 10-5 Pa pressure. The sample GO-Sb-80 was heated at 80 °C
for 5 h, the samples rGO-Sb-300 and rGO-Sb-650 were heated for 2 h at 300 °C and 650 °C,
respectively. Heating to the set point was conducted at a rate of 0.8 °C min-1 to prevent loss of
the products by carryover.
Characterizations: High Resolution Transmission Electron Microscope (HRTEM) studies were
conducted using FEI Technai F20 G2 (Eindhoven, Holland). HRTEM imaging was performed at
200 kV. A drop of the suspension of the sample in ethanol was deposited onto 400 mesh copper
grids covered with a lacey carbon net.
X-ray powder diffraction (XRD) measurements were performed on a D8 Advance
Diffractometer (Bruker AXS, Karlsruhe, Germany) with a goniometer radius 217.5 mm, Göbel
Mirror parallel-beam optics, 2° Sollers slits and 0.2 mm receiving slit. The powder samples were
carefully filled into low background quartz sample holders. The specimen weight was
approximately 0.5 g. XRD patterns from 5° to 75° 2θ were recorded at room temperature using
CuKα radiation (k=1.5418Å) under the following measurement conditions: tube voltage of 40
kV, tube current of 40 mA, step scan mode with a step size 0.02° 2θ and counting time of 1
s/step. XRD patterns were processed using Diffrac Plus software.
X-ray Photoelectron Spectroscope (XPS) measurements were performed on a Kratos Axis Ultra
X-ray photoelectron spectrometer (Manchester, UK). High resolution spectra were acquired with
a monochromated Al Kα (1486.6 eV) X-ray source with 0° takeoff angle. The pressure in the test
chamber was maintained at 1.7∙10−9 Torr during the acquisition process. Data analysis was
performed with Vision processing data reduction software (Kratos Analytical Ltd.) and
CasaXPS.(Casa Software Ltd.).
Surface area measurements were performed using the N2-BET method on a Nova-1200e
analyzer.
II. Figures and Tables
Charging capacity of graphene oxide LIB anode
Figure S1 Charging capacity of neat graphene oxide carried out at the range 0 – 2.5 V. First 5
cycles were carried out at a rate of 50 mA g-1 and the others were taken at 100 mA g-1.
Calculation of the specific charging capacity of the antimony ingredient in rGO-Sb-650
The observed specific capacity of the antimony ingredient in the rGO-Sb-650 electrode can be
calculated based on the following assumptions:
1. The contribution of the graphene is 270 mAh g-1 (based on Fig. S1)
2. The reversible capacity at 250 mAhg-1 is 340 mAhg1- (Figure 5a after 50 cycles).
3. The electrode contains a composition as depicted in Table 1. For every portion of
carbon, there are 0.28 portions of antimony and 0.27 portions of oxygen (by weight).
4. The carbon and the binder ingredients in the electrode bear negligible contribution to the
charge capacity.
The equation for calculation of the charging capacity is then given by:
[340*(1. +0.28 +0.27)- 270*(1+0.27)]/0.28 = 658 mAh (g Sb)-1
In fact, even if we assume that the EDX results are biased and the ratio of antimony to carbon is
0.3 we still receive 574 mAh (g Sb)-1.
XPS Studies of rGO-Sb-300 and rGO-Sb-650
Figure S2 XPS signal of antimony in rGO-Sb-300 and rGO-Sb-650 with the deconvoluted O 1s
and Sb 3d 5/2 signals. The Sb 3d 3/2 is at 540 eV in both samples showing that at least the
surface is covered by antimony oxide. The binding energy of the small deconvoluted peak of
Sb(0) is lower by 2.0 eV versus the main antimony oxide peak.
Specific surface area tests
Table S1 Specific surface area of the graphene oxide (GO) and coated graphene oxide after
different heat treatments.
Temperature, ºC
GO, m2 g-1
Coated GO, m2 g-1
80
300
650
93
302
102
22
238
310
We assume that increased crystallinity of the coating opens up the otherwise stacked graphene
oxide coated sheets. The distortion of the flat sheets by heat treatment also prevents stacking and
increases the specific surface area. Sheets distortion is also responsible for the increased specific
surface area of uncoated graphene oxide upon heat treatment to 300 ºC, but high temperature
treatment also reduces the graphene oxide and the hydrophobic interaction between the sheets
dominates. We do not observe increased stacking propensity in the coated reduced graphene
oxide due to the steric hindrance of the coating.
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