suppressed polysulfide crossover in li-s batteries through a high
TRANSCRIPT
1
Supporting Information
Suppressed Polysulfide Crossover in Li-S
Batteries Through a High-Flux Graphene Oxide
Membrane Supported on Sulfur Cathode
Mahdokht Shaibani,†, ‡ Abozar Akbari,
† Phillip Sheath,
† Christopher D. Easton,
‡ Parama
Chakraborty Banerjee,† Kristina Konstas,
‡ Armaghan Fakhfouri,
† Marzieh Barghamadi,
‡, §
Mustafa M. Musameh,‡ Adam S. Best,
‡ Thomas Rüther,
‡ Peter J. Mahon,
§ Matthew R. Hill,
*,‡,
^ Anthony F. Hollenkamp,
*,‡ and Mainak Majumder
*,†
† Nanoscale Science and Engineering Laboratory (NSEL), Department of Mechanical and
Aerospace Engineering, Monash University, Clayton, VIC 3168, Australia ‡
CSIRO, Clayton, VIC 3168, Australia § Department of Chemistry and Biotechnology, Swinburne University of Technology, VIC
3122, Australia
^ Department of Chemical Engineering, Monash University, Clayton, VIC 3168, Australia
Table of contents
Section SI. Materials
Section SII. Supporting Figures
Figure S1 SEM images of uniformly coated sulfur cathode and poorly coated sulfur cathode
Figure S2 Characterization of the porous structure of the microporous carbon
Figure S3 High resolution C 1s XPS spectrum of carbon coated separator
Figure S4 Cyclic voltammogram of GO coating alone
Figure S5 Cyclic voltammogram of GO coated cathode
Figure S6 FTIR spectrum of GO coated cathode
Figure S7 High resolution C 1s XPS spectrum of GO coated cathode
Figure S8 Effect of giving a resting time before cycling
Figure S9 Capacity Contribution of the GO coating
2
Figure S10 Capacity retention of GO coated electrode after 400 cycles at different lower rates
Figure S11 Influence of the structural order of GO membrane on the performance of Li-S cell
Figure S12 Proposed electrical equivalent circuit (EEC)
Figure S13 Comparison of the experimental and the simulated EIS data
Figure S14 Effect of GO coating thickness on cyclability
Figure S15 Effect of the conductive interlayer thickness on cyclability
Figure S16 Cycling performance in a liNO3-free electrolyte
Section SIII. Supporting Tables
Table S1 Calculated resistances of the different interfaces of cells with different separators
Table S2 Survey data measured by XPS
Table S3 Component fitting of high resolution S 2p spectra measured by XPS
Table S4 Comparison of the performances of advanced Li-S cells
Table S5 Comparison of the performances of Li-S cells with GO in their configuration.
Section SI. Materials
Graphite powder (SP-1 grade 325 mesh) was purchased from Bay Carbon Inc. Microporous
carbon (Black Pearls 2000) was purchased from CABOT Co. Potassium persulfate,
Phosphorus pentoxide, Potassium permanganate, Ammonium persulfate, N-methyl-2-
pyrrolidinone, Bis(trifluoromethane)sulfonimide lithium salt and Lithium nitrate were
purchased from Sigma-Aldrich and directly used without any further purification.
Battery grade etched Al foil (30 µm thickness) was purchased from Japan Capacitor
Industrial Co. Solupor 7P03A separator was purchased from Lydall, Inc., UK and Glass fiber
BG03013 separator (0.203 mm, max pore size= 15.5 µm) was purchased from, Hollingsworth
& Vose (H&V), USA. Cross-linked polyacrylate copolymer based hydrogel beads were
purchased from Demi Co, Ltd, China. Cross-linked polyacrylate copolymer based hydrogel
beads were purchased from Demi Co, Ltd, China.
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Section SII. Supporting Figures
Figure S1. Effect of the gap size of the doctor blade -which demonstrates the thickness of the
GO membrane - on the coverage of the GO coating on the cathode: (a) SEM image of a GO
coated cathode with a large enough gap size of the doctor blade showing uniform coverage of
the cathode surface. (b) SEM image of a GO coated cathode with a not large enough gap size
of the doctor blade revealing electrode areas which are not covered with the GO membrane.
Decreasing the thickness of the coated GO membrane is limited only by the surface
roughness of the cathode.
1 µm 1 µm
a b
S cathode
GO coting
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Figure S2. Characterization of the porous structure of the microporous carbon used in this
work for fabricating carbon coated separators: (a) N2 adsorption isotherm at 77K, (b) Pore-
size distribution.
Figure S3. High resolution C 1s XPS spectrum of carbon coated separator.
a b
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Figure S4. Control experiment on the GO coating on Al foil, without the sulfur cathode:
Cyclic voltammetry at 0.1 mV s-1
in a potential window from 1.8 to 2.8 V vs Li+/Li
0.
Figure S5. Cyclic voltammetry of GO coated electrode at 0.1 mV s-1
in a potential window
from 1.8 to 2.8 V vs Li+/Li
0.
6
Figure S6. FTIR spectrum of graphene oxide coated electrode shows hydroxyls (broad peak
at 3000-3800 cm-1
), carboxyls (1650-1750 cm-1
) and ethers and/or –C-O- (1000-1280 cm-1
).
Figure S7. High resolution C 1s XPS spectrum of graphene oxide coated electrode. Various
carbon-oxygen functional groups, including hydroxyl, epoxy, and carboxylic acid, are likely
present in the GO membrane as represented by the signal intensity at binding energies
greater than ~ 286 eV, and supported by the FTIR results.
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Figure S8. Effect of resting time before cycling: Putting a cell on rest for 24 h before cycling
at a high 1 C rate allows for the electrolyte to diffuse through the GO layer and wet the sulfur
cathode. Accordingly the cell starts at its highest capacity compared to a cell which was
cycled immediately after assembly and requires some activation cycle to reach its maximum
capacity.
Figure S9. Capacity Contribution of the GO coating: (a) Charge discharge V-t profiles of GO
coating at the same current density as a typical Li-S cell in this work in a potential window
from 1.8 to 2.8 V vs Li+/Li
0. (b) Cycling performance comparison of GO coating at the same
current density as a typical Li-S c ell in this work shows negligible capacity contribution
from the GO coating.
a b
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Figure S10. Capacity retention of GO coated cathode after 400 cycles at different lower rates:
After 400 cycles the cells can still maintain specific capacities of 1100 mAh g-1
at 0.1 C, 985
mAh g-1
at 0.2 C and 885 mAh g-1
at 0.5 C rates providing one of the best performances
demonstrated so far for a Li-S cell.
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Figure S11. Influence of the structural order of the GO membrane on the
electrochemical response and performance fading of the Li-s battery: (a) Configuration
of a cell assembled with a bare separator, (b) configuration of a cell assembled with a shear-
aligned GO coated separator made by blade coating, (c) configuration of a cell assembled
with a disordered GO coated separator made by vacuum filtration technique. (d) Comparing
the 1st cycle of cells a, b and c; (e) comparing the 5
th cycles of cells a, b and c.
Predicted organization of
graphene sheets in the
Vacuum filtered GO film
on the separator 1, 2
Li
Separator
Sulfur cathode
Predicted organization of
graphene sheets in the
Shear aligned GO film
on the separator
a b c
d e
Go coated Separator Go coated Separator
Sulfur cathode Sulfur cathode
Li Li
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Figure S12 Proposed electrical equivalent circuit (EEC) to analyse the impedance data of the
cells containing a bare separator, an ordered and a disordered GO coated separators. In this
study, complex nonlinear least square method was used to analyse the data. The fitting
procedure, weighing modulus and circuit description codes are explained elsewhere.3
Figure S13 Comparison
of the experimental and the simulated (a) Nyquist, (b) Bode |Z| and (c) Bode phase angle
plots of a cell assembled with a sheer aligned GO coated separator made by blade coating. A
good agreement between the simulated and experimental data confirms the validity of the
proposed EEC. (d) Error plot of the same cell shows less than 5 % error in |Z|, and the error
in angle simulation was less 4 degree.
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Figure S14. Effect of GO coating thickness on cyclability (1C rate): A thicker coating
clearly interferes with both ion movement and mass transport.
≈ 0.80 µm thick GO film on the
cathode ≈ 1.60 µm thick GO film on the cathode
12
Figure S15. (a) Cross section SEM image of a relatively heavy carbon coated separator (≈ 15
µm and ≈ 0.7 mg cm-2
), (b) SEM image of a lightweight carbon coated separator (≈ 6.5 µm
and ≈ 0.24 mg cm-2
), (c) Effect of the mass of the conductive interlayer on the cycling
performance of GO coated cathodes. If we only consider the sulfur utilization (mAh g-1
S) the
specific capacity of the cell configured with a heavy conductive interlayer is slightly higher.
However if we take into account the mass of the whole cathodic system (Cathode (sulfur+
conductive agent+ binder) + Additional layers (GO on the cathode and carbon on the separator)), the total gravimetric
capacity of the cell with a lightweight coating is ≈ 280 mAh g-1
which is significantly higher
than that of the cell with a heavy coating: ≈ 216 mAh g-1
.
a b
c
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Figure S16. Cycling performance in a liNO3-free electrolyte.
Section SIII. Supporting Tables
Table S1 Calculated resistances of the different interfaces of the cells containing bare
separator, sheer aligned GO coated separator and disordered GO coated separator before and
Sample Re (Ω) Rint (Ω) Rct (Ω)
Before after Before after Before after
Bare separator 5 7 108 200 31 194
Sheer aligned GO
coated separator
8 6 83 107 132 148
Disordered GO coated
separator
9 12 99 181 106 236
14
after 5 cycles of CV
15
Table S2. Survey data measured by XPS (atomic percentage, %). Listed are the mean values
(± deviation) based on +2 analyses points.
Sample: Un-coated cycled cathode
GO-coated cycled cathode
Atomic% Mean Std Mean Std
Na 1s 0.08 0.03 0.00 0.00
F 1s 20.13 1.47 23.20 1.62
O 1s 25.88 0.65 29.82 0.55
N 1s 4.27 0.10 3.67 0.13
C 1s 25.03 1.16 21.18 0.33
S 2p 11.14 0.37 8.29 0.23
Li 1s 13.45 1.18 13.85 1.34
Si 2p 0.03 0.05 0.00 0.00
Table S3. Component fitting of high resolution S 2p spectra measured by XPS (atomic
percentage, %). Listed are the mean values (± deviation) based on 3 analyses points.
Sample
Un-coated cycled cathode
GO-coated cycled cathode
Atomic% Mean Std Mean Std
S 1 4.79 0.32 2.85 1.00
S 2 27.96 2.78 6.08 2.79
S 3 6.97 0.27 2.22 1.23
S 4 2.25 0.75 2.19 0.45
S 5 12.74 0.58 4.82 1.39
S 6 19.57 1.05 34.88 0.80
S 7 25.72 2.55 46.97 4.63
S 2p components:
S 1: Li2S; S*-SO3 (thiosulphate)
S 2: Li2S2; polysulfide (Sterminal)
S 3: polysulfide (Sbridge)
S 4: S8
S 5: Range of oxidised and S+ groups
S 6: Sulfite (RSO3); RS(O)OR
S 7: Sulfate (RSO4); ROSO2OR, RSO2F
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Table S4. Performance of the state of the art Li-S batteries.
a Values were extracted from the main texts. b Values were estimated from the relevant
figures.
Sulfur
Fraction
(%)
Sulfur
Loading
(mg cm-2
)
Interlyer
weight
(mg cm-2
)
Rate /
cycle
Discharge capacity at nth
cycle per mass
of
(mAh g-1
)
sulfur composite
cathode
composite
cathode
+interlayer
GO/Amylopectin
host 4a
52 4 N/A 0.5 C (100) 430 223 N/A
Hollow core-shell
interlinked carbon
spheres host 5a
52.5 1 N/A 0.5 C (200) 960 504 N/A
Mesoporous
Carbon Nanotube
host 6a
60 1.87 N/A 0.1 C (100) 866 520 N/A
polar, high surface
area metallic oxide
host 7a
48
56 0.75-0.9 N/A
0.5 C (100)
0.5 C (100)
870
850 417
476 N/A
g-C3N4
polar host 8a
56 1.5 N/A 1 C (200) 730 408 N/A
PEDOT:PSS-
coated CMK-
3/sulfur composite 9a
43 1 N/A 0.2 C (150) 600 258 N/A
Phenyl sulfonated
graphene/sulfur10
63 1.15-1.77 N/A
0.2 C (50)
0.2 C (400)
717
460 452
290
GO on the
separator 11b
63 1-1.5 0.12 0.1 C (100) ~700 ~ 441 ~ 376
GO/O-CNT on the
separator 12b
65 1.2-1.4 0.3 1 C (100) ~ 750 ~ 487 ~ 300
CNF interlayer 13a
60 1.4 4.2 0.2 C (100) 1161 696 73
Polypropylene/
Graphene
Oxide/Nafion
separator 14b
54 1.2 0.0532 0.1 C (100) ~850 ~ 459 ~ 408
SWCNT
Modulated
Separator 15b
75 1.5 0.13 0.5 C (100)
0.5 C (300)
~800
501
~ 600
375 ~ 484
302
Graphene current
collector + vacuum
filtered graphene
separator 16b
70 3-4 1.3 0.75 A g
-1
(100)
~950
~665
~527
This work
35
70
80
1-1.2
1-1.2
1.3-1.4
0.29 0.5 C (100)
1003
1190
1040
350
834
835
278
572
577
17
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Table S5. Comparison of the performances of Li-S cells with GO in their configuration.
a Values were extracted from the main texts.
b Values were estimated from the relevant
figures.
Electrolyte Rate 1st
discharge
capacity, mAh g-1
Discharge
capacity at nth
cycle, mAh g-1
Coulombic
efficiency, %
GO/S cathode 17a
Organic
IL
0.1 C
0.1 C
1014
1014
736 (16)
954 (50)
96.7
GO/S/CTAB cathode 18b
Organic
IL
1.0 C
1.0 C
~860
~860
~640 (100)
~680 (400)
96.7
96.3
GO/S/Amylopectin
cathode 4a
Organic
0.5 C 596 430 (100) 98
GO coated separator 11b
Organic 0.1 C ~1000 ~700 (100) 95-98
This work Organic
Organic
Organic
1.0 C
1.0 C
0.2 C
1170
1170
1616
950 (100)
750 (400)
1200 (100)
~100
99.75
99.55
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