(a)lfnazar/publications/natcommun_2015_6_5682... · supplementary figure 1. thermogravimetric...
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Supplementary Figure 1. Thermogravimetric analysis of materials. (a) as prepared MnO2
nanosheets, (b) 75S/MnO2 prepared by melt diffusion at 155 oC. TGA studies were carried out at a
flow rate of 10 oC/min under air.
(b)
(a)
3% interlayer water
Supplementary Figure 2. SEM micrograph of the sulfur-MnO2 nanosheet mixture before melt
diffusion.
Supplementary Figure 3. EDS mapping of S, Mn, K and O in a representative S/MnO2 nanosheet
composite particle.
Supplementary Figure 4. Summary of polysulphide adsorptivity per 10 mg of active material as
determined by an electrochemical titration method.1
Supplementary Figure 5. S 2p spectrum of sodium thiosulphate and its mixture with Li2S4
(Na2S2O3-PS). To prepare the material, 80 mg anhydrous Na2S2O3 and 20 mg Li2S4 were stirred
for 2 hours in 10 ml of DME in the glovebox, and Na2S2O3-PS was collected by centrifugation. For
sodium thiosulphate alone (a), there are two sulphur environments: the S 2p3/2 peak at 167.5 eV (red)
is attributed to the central S=O while the S 2p3/2 peak at 161.5 eV (blue) is from the peripheral S in
the thiosulphate that bears the negative charge. For Na2S2O3-PS (b), we observe the S 2p3/2 signal of
the central S (red) and peripheral S for thiosulphate (blue) and the terminal S (blue, overlapped) and
bridging S (green) of the residual polysulphides. An additional peak at 168.8 eV (magenta) appears
for the Na2S2O3-PS sample, which is attributed to the reaction of thiosulphate and polysulphides to
form the polythionate complex (see text). This peak can be ascribed to the S=O in the polythionate,
whereas its bridging sulphur atoms are overlapped with those of the SB0 in S4
2-.
Binding Energy (eV)
a)
b)
Supplementary Figure 6. FTIR spectra of Li2S4; MnO2-Li2S4; -MnO2 and Na2S2O3; see legend.
The spectra were collected under N2.
Supplementary Figure 7. C 1s spectrum of graphene oxide (GO) and GO-Li2S4 (GO-LiPS).
The C 1s region of GO are assigned to 3 components: C-C at 285 eV (which dominates any traces of
adventitious carbon in the sample), C-O or C-OH at 287 eV, and C=O at 288.2 eV. The relative
intensity ratio of the C-C : C-O groups increases from 1.4: 1 for GO to 1.8: 1 for GO-Li2S4,
indicating that GO is slightly reduced by LiPS on the surface. In addition to the increased C-C
intensity, the C-O(H) peak is shifted by 0.7 eV to lower binding energy and the C=O peak is shifted
by 0.9 eV to higher binding energy. Exactly the same peak shift was reported in thermally reduced
GO by Zangmeister, C. D.2
C-C C-O(H)
C=O
Supplementary Figure 8. Comparison of the atomic concentration of each identified S 2p peak for
the electrodes discharged to specific states.
Polythionate
complex
Supplementary Figure 9. High resolution S 2p XPS analysis of (a) Na2S2 and (b) Li2S. The
spectra demonstrate that the S22-
groups in Na2S2 and the S2-
groups in Li2S exhibit S 2p3/2 binding
energies of 161.8 and 160.2 eV, respectively.
(b)
(a)
Supplementary Figure 10. Ex-situ XPS measurements of the 75S/MnO2 nanosheet electrodes on
partial charge.
Polythionate
complex
Thiosulfate
S8
SB0 ST
-1
Supplementary Figure 11. Rate capability of the 75S/MnO2 nanosheets at various current
densities. The cells were cycled in a 1.8- 3.0 V window at current densities corresponding to rates of
C/20, C/5, C/2 and 1C; a window between 1.7- 3.0 V was used for the 2C, 3C rates; and a window of
1.6- 3.0 V for 4C rates (1C = 1675 mA g-1
).
Supplementary Figure 12. SEM images showing the similarity in the morphology of a) the fresh
75S/MnO2 electrode, and b) after 1000 cycles.
Supplementary References:
1 Dominko, R.; Demir-Cakan, R.; Morcrette, M.; Tarascon, J.-M. Analytical detection of soluble
polysulphides in a modified Swagelok cell. Electrochem. Commun., 13, 117-120 (2013) 2 Zangmeister, C. D. Preparation and evaluation of graphite oxide reduced at 220⁰C. Chem. Mater. 22, 5625–
5629 (2010).