Supplementary material

Exceptional Adsorption and Catalysis Effects of Hollow Polyhedra/Carbon

Nanotube Confined CoP Nanoparticles Superstructures for Enhanced Lithium-

Sulfur Batteries

Zhengqing Yea, Ying Jianga, Ji Qiana, Wanlong Lia, Tao Fenga, Li Lia,b, Feng Wua,b, and

Renjie Chena,b,*

aBeijing Key Laboratory of Environmental Science and Engineering, School of

Material Science and Engineering, Beijing Institute of Technology, Beijing 100081,

China.

bCollaborative Innovation Center of Electric Vehicles in Beijing, Beijing 100081,

China.

E-mail: chenrj@bit.edu.cn

1

Fig. S1 SEM images of (a) ZIF-8, (b) ZIF-8/ZIF-67, and (c) Co@HPCN. (d) TEM

images of the as-prepared Co@HPCN.

2

Fig. S2 XRD patterns of the (a) ZIF8 and ZIF-8/ZIF-67, (b) Co@HPCN and (c) Co3O4@HPCN.

3

Fig. S3 TEM and HRTEM images of CoP@HPCN.

4

Fig. S4 HRTEM images of CoP@HPCN.

5

Fig. S5 TGA curves of CoP@HPCN samples treated in air.

6

Fig. S6 TGA curve of the CoP@HPCN/S composite.

7

Fig. S7 (a,b) HRTEM images, (c) Nitrogen adsorption–desorption isotherms, and (d) DFT pore size distributions of the CoP@HPCN/S material.

The nitrogen isotherm of CoP@HPCN/S shows a significant rise at a high relative pressure, indicating the macropore structure derived from the hollow interior. (Fig. S7c). A pore size distribution of CoP@HPCN/S exhibits some mesopores and macropores (Figure S7d, Supporting Information). Therefore, hollow polyhedra with interior cavities and mesoporous shell can relieve volumetric expansion during lithiation.

8

Fig. S8 Results of (a) Li2S6 and (b) Li2S8 adsorption experiments with MWCNT and CoP@HPCN.

9

Fig. S9 CV curves of the symmetric cell employing CoP@HPCN-MWCNT at various scan rates.

10

Fig. S10 Discharge–charge curves of CoP@HPCN-MWCNT/S and MWCNT/S

electrodes at 0.2 C.

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Fig. S11 CV curves of (a) CoP@HPCN-MWCNT/S and (b) MWCNT/S composite

cathode at a scan rate of 0.1 mV s−1.

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Fig. S12 Cyclic performance of CoP@HPCN/S electrode at 0.2 C.

13

Fig. S13 (a) voltage profiles of the MWCNT/S at 1st and 300th cycles. (b) The

comparison of high and low plateau of the CoP@HPCN-MWCNT/S and MWCNT/S

cathodes at 1st and 300th cycles.

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Fig. S14 Cycling stability of CoP@HPCN-MWCNT/S cathode at 2 and 3 C.

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Fig. S15 Galvanostatic discharge/charge profiles of (a) CoP@HPCN-MWCNT/S and (b) MWCNT/S at various current rates (0.1, 0.2, 1, 2, and 3 C).

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Fig. S16 (a) CV curves of CoP@HPCN-MWCNT/S cathode at various scan rates.

The calculated b values with plots of log(current) versus log(scan rate) for (b) peak 1,

(c) peak 2, (d) peak 3, and (e) peak 4.

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Fig. S17 (a) The discharge capacity of CoP@HPCN-MWCNT/S electrodes with (a)

2.3 mg cm−2 and (b) 3.7 mg cm−2 before (rhombus) and after (sphere) 60 days of rest

at room temperature.

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Fig. S18 Self-discharge performance comparison of the CoP@HPCN-MWCNT/S

electrode with other sulfur cathodes reported in literature.

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Fig. S19 The calculated lithium diffusion coefficient D (cm2 s−1) of CoP@HPCN-

MWCNT/S and MWCNT/S electrodes before and after 200 cycles at 0.2 C.

The lithium ion diffusion coefficient from EIS can be calculated from the

formula as following: D=R2T2/(2A2n4F4C2σ2). where R is the gas constant (R= 8.314 J

K−1 mol−1), T is the room temperature in our experiment (T=298K), A is the electrode

area, n is the electron charge number (n=2), F is the Faraday constant, C is the

concentration of lithium ion (0.001 mol cm−3), σ is the slope of the line Z’∼ω−1/2,

which can be obtained from the fitted line of Z’∼ ω−1/2.

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Table S1. The comparisons of electrochemical properties of present work with

various cathode materials for Li-S batteries.

Cathode materials

S content (wt.%)

S loading(mg m-

2)

Initial capacity(mAh g-

1/C)

Reversible capacity

(mAh g-1)/Cycle

number

Decay rate

(%per cycle)

Rate properties

(mAh g-1/C)S loading(mg cm-2)

VO2 hollow spheres [S1] 71 -

930/0.1789/80 0.15

318/2-

TiO2/Co-carbon

polyhedras [S2]

66 1.5 -/1 466.3/300 - 383.8/31.5

Co3O4/ ACNT hybrid spheres

[S3]58.7 1.5

748.7/0.5496.5/550 0.064

589/21.1

Mn-Sn oxide nanocubes [S4] - 0.65–1.0

-/0.2390.7/300 -

107.5/10.65–1.0

C@TiN hollow nanosphere

[S5]70 -

1309/0.2884/100 0.3

591/21.1

NiCo2S4@CNTs

[S6]66 1.8

-/2310/100

470/30.4-0.79

ZnCo2O4@N-RGO [S7]

71 1.1–1.3905/1.6A

g−1 645/200 0.144 -

PANI@EDA-CNTs [S8]

72 2992/0.5

735/200 0.130462/3

2

Fe/Fe3C@N-CNT [S9]

- - 932/1 534/300 0.142464/2

p-CNT@Void@

MnO2 [S10]64.9 - 599/1 561/100 - 496.9/2

CoP@HPCN-MWCNT

(This work)70 2.2

887/0.2 753/200 0.076601/2

527.7/31.1

21

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