1

Supplementary Information

Vertical Co9S8 hollow nanowall arrays grown on Celgard

separator as a multifunctional polysulfide barrier for high-

performance Li-S batteries

Jiarui He,a,b Yuanfu Chen,b,* and Arumugam Manthirama,*

a Materials Science and Engineering Program & Texas Materials Institute, The University of Texas at Austin, Austin, TX 78712, USAE-mail: manth@austin.utexas.edu

b State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, PR China

E-mail: yfchen@uestc.edu.cn

Fig. S1 Photographs of as-prepared MOF-Celgard separator: (a) Front side, (b) back side, and (c) folded; (d) scalable production of MOF-Celgard separator.

Electronic Supplementary Material (ESI) for Energy & Environmental Science.This journal is © The Royal Society of Chemistry 2018

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Fig. S2 Photographs of Co9S8-Celgard separator.

Fig. S3 (a) XRD patterns of MOF, Celgard, and MOF-Celgard separators. (b, c and d) Top-surface morphology of MOF-Celgard at various magnifications. The inset shows a digital photo. (e, f and g) Cross-sectional morphologies of MOF-Celgard, and the corresponding elemental mapping images of (h) cobalt and (i) carbon.

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Fig. S4 SEM images of Celgard separator.

Fig. S5 (a) SEM image of Co9S8-Celgard separator from top surface and the corresponding elemental mapping images of (b) sulfur, (c) cobalt, and (d) carbon. (e) EDX spectrum of Co9S8-Celgard separator from top surface.

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0.0 0.2 0.4 0.6 0.8 1.0

0

50

100

150

Volu

me

Abso

rbed

(cm

3 g-1)

P/P0

MOF Co9S8 arrays

10 1000.000

0.001

0.002 MOF Co9S8 arrays

dV/d

D (c

m3 g

-1 n

m-1)

Pore Size (nm)

a b

Fig. S6 (a) The specific surface area and (b) pore size distribution of MOF and Co9S8.

Fig. S7 Photographs of (a) Co9S8-Celgard and (b) MOF-Celgard separator with repeatedly bending 50 times.

Fig. S8 SEM images of the sulfur cathode.

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1.8 2.1 2.4 2.7 3.0-2

-1

0

1

2

3

Curr

ent (

mA

cm-2)

Potential (V)

1st 2nd 3rd

Fig. S9 CV curves of the Li-S batteries with Co9S8-Celgard separator at 0.1 mV s-1 at 1.8 - 2.8 V.

0 20 40 601.8

2.1

2.4

2.7

Pote

ntia

l (V)

1st 10th 20th 30th

Specific Capacity (mA h g-1)

Fig. S10 Charge/discharge curve of Co9S8 at 0.1 C rate, the specific capacity is calculated by the weight of Co9S8.

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10μm

a

10μm

b

c d

10μm 10μm

Fig. S11 SEM images of (a) fresh Li foil, (b) cycled Li foil in the cell with the Co9S8-Celgard separator, (c) cycled Li foil in the cell with the MOF-Celgard separator, and (d) cycled Li foil in the control cell with bare Celgard separator after 200 cycles.

20μm

d e

a b

FS

c

f

O

Co5μm

g

Fig. S12 (a, b) SEM images of Co9S8-Celgard separator from top surface after 200 cycles and the corresponding elemental mapping of (c) cobalt, (d) sulfur, (e) fluorine, and (f) oxygen. (g) EDX spectrum of Co9S8-Celgard separator top surface after 200 cycles.

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Fig. S13 SEM images of Co9S8-Celgard separator from top surface at (a) discharge and (b) charge states.

Fig. S14 SEM images of the MOF-Celgard separator from the top surface after 200 cycles.

0 50 100 150 2000

400

800

1200

1600

Spec

ific

Capa

city

(mAh

g-1)

Cycle Number

2 mg cm-2

3.5 mg cm-2

5.6 mg cm-2

Fig. S15 Cycling performances of Li-S cells with high sulfur loading cathodes with Co9S8-Celgard separators.

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0 30 60 90 1200

20

40

60 Celgard MOF-Celgard Co9S8-Celgard

-Z'' (

ohm

)

Z' (ohm)Fig. S16 EIS plots of the fresh cells with Celgard, MOF-Celgard, and Co9S8-Celgard separators.

2000 1800 1600 1400 1200 1000 800 600

Tran

sim

itanc

e (a

.u.)

Wavenumber (cm-1)

Celgard MOF-Celgard MOF-Celgard cycled

Co=S

Fig. S17 IR spectra of the MOF-Celgard separators before and after the electrochemical process.