Supporting Information

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1 Copyright WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany, Supporting Information for Adv. Mater., DOI: /adma Generalizable Synthesis of Metal-Sulfides/Carbon Hybrids with Multiscale, Hierarchically Ordered Structures as Advanced Electrodes for Lithium Storage Chao Wu, Joachim Maier, and Yan Yu*

2 Supporting Information Generalizable Synthesis of Metal-Sulfides/Carbon Hybrids with Multi-Scale, Hierarchically Ordered Structures as Advanced Electrodes for Lithium Storage Chao Wu, 2 Joachim Maier, 2 and Yan Yu *,1,2,3 Prof. Dr. Y. Yu 1 CAS Key Laboratory of Materials for Energy Conversion Department of Materials Science and Engineering University of Science and Technology of China Hefei , China yanyumse@ustc.edu.cn Dr. C. Wu, Prof. Dr. J. Maier, and Prof. Dr. Y. Yu 2 Max Planck Institute for Solid State Research, Heisenbergstr.1, Stuttgart 70569, Germany Prof. Dr. Y. Yu 3 State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui, , China Keywords: Multi-scale, Multi-dimension, Hierarchic structure, Transition-metal sulfides, Lithium storage EXPERIMENTAL SECTION Synthesis of TS pcw GN and TS pcw. In a typical synthesis, graphene oxide (GO) was prepared by modified Hummers s method. Take the synthesis of NiS pcw GN as an example, 1.4 g of NiCl 2 6H 2 O was dissolved into 30 ml of deionized water, and then 0.6 g of nitrilotriacetic acid (NTC) and 10 ml of 2-propanol were added into the above solution. The mixed solution was transferred into Teflon vessel for solvent-thermal reaction. After reaction for 6 h at 180 o C, a blue NTC-Ni nanowire precursor was obtained by washing and filtering separation. Then, 0.3 g of the desired NTC-Ni precursor was re-dispersed into 50 ml of deionized water, followed by mixing with 50 ml of GO aqueous solution (2 mg ml -1 ) to form a stable precursor solution. 10 ml of cetyltrimethyl ammonium bromide (CTAB) aqueous solution (0.5 mg ml -1 ) was stepwise added to the precursor solution to obtain the coagulum consisting of 1

3 NTC-Ni and GO because of the strong electrostatic interaction between GO and CTAB. The NTC-Ni/GO coagulum was collected, dried, and mixed with sulfur powders. After annealing at 650 o C for 2 h with a heating rate of 2 o C min -1, the resulting product was further mixed with sulfur powder and annealed at 650 o C for 2 h to obtain the desired NiS pcw GN product. CoS pcw GN and MnS pcw GN were synthesized by the same process as NiS pcw GN. The contents of NiS and CoS for NiS pcw GN and CoS pcw GN are 73% and 70 wt%, respectively, which are measured by etching the TS particles with dilute HCl solution. TS pcw (T=Ni, Co, Mn) was synthesized using the above process without the assembly step with GO. Synthesis of TS-GN. In a typical synthesis, 1 mmol of Ni(OCOCH 3 ) 2 4H 2 O and 1.5 mmol of L- cysteine were dissolved into 50 ml of GO aqueous solution, and the ph value of the solution was adjusted to 10 by adding ammonia water. Then, the solution was transferred into Teflon vessel for solvent-thermal reaction. After reaction for 12 h, the resulting product was collected, dried and mixed with sulfur powder. The mixture was annealed at 650 o C for 2 h to obtain the desired NiS- GN product. The content of NiS for NiS-GN is about 70 wt%. Similar method was used to synthesize CoS-GN and MnS-GN. Materials characterization. The morphology of the as-prepared samples was investigated by field-emission scanning electron microscopy (FE-SEM, Zeiss Gemini DSM 982) and transmission electron microscopy (TEM, JEOL 4000 FX, 400 kv). Nitrogen adsorption and desorption isotherm measurement were performed with a Quanta Chrome Adsorption Instrument. The crystal structures of the as-prepared samples were recorded by X-ray diffraction (XRD) (Philips) using Cu Ka radiation. Electrochemical measurement. The electrochemical measurements were carried out in a type coin-cell with a metallic lithium film as the counter electrode and with 1M lithium bis-(trifluoromethanesulfonyl)imide LiTFSI in 1,3-dioxolane/dimethoxymethane (1:1, by volume) as electrolyte. For TS pcw GN, the working electrodes were made by casting slurry containing active material and PVDF binder with a mass ratio of 9:1 on a Cu foil. For TS pcw and TS-GN, the working electrodes were made by casting slurry containing active material, carbon black and PVDF binder with a mass ration of 8:1:1 on a Cu foil. Note that all the capacity values for the NiS pcw GN, CoS pcw GN, NiS pcw, CoS pcw, Ni-GN, and Co-GN cathodes (voltage range from 1 to 3 V) are calculated based on the mass of metal sulfides. Considering that 2

4 carbon has non-real contributions to capacities in the low voltage range (< 1V), the capacities of MnS pcw GN and MnS pcw (voltage range from 0.1 to 2.5 V) as well as CoS pcw GN (voltage range from to 3 V) are calculated based on the mass of carbon and sulfides. All the volumetric capacities are calculated based on the volume of carbon and sulfides. The as-prepared electrodes were dried at 80 o C for 12 h, and then assembled into the coin cells in a glove filled with argon. The galvanostatic charge-discharge tests were performed on a battery system (Neware BTS). Cyclic voltammetry measurements were carried out by an electrochemical workstation (VoltaLab 80) at different scan rate. Electrochemical impedance spectrum measurements were performed on an electrochemical workstation (Chenhua, Shanghai) in the frequency range from 100 KHz to 0.1 Hz. Figure S1. Elemental mapping images of NiS pcw GN. (a) Typical SEM image and corresponding elemental mapping images of (b) carbon, (c) nickel, and (d) sulfur, indicating the homogeneous dispersion of C, Ni, and S in the NiS pcw GN composite. 3

5 Figure S2. SEM images and magnified SEM images of (a-b) NiS pcw, (c-d) CoS pcw, and (e-f) MnS pcw. 4

6 Figure S3. XRD patterns of (a) NiS-GN, (c) CoS-GN and (e) MnS-GN, indicating that TS corresponds to monosulfides. SEM images of (b) NiS-GN, (d) CoS-GN and (f) MnS-GN. 5

7 Figure S4. TEM images of of (a) NiS pcw, (c) CoS pcw, and (e) MnS pcw. 6

8 Figure S5. Raman spectra of NiS CW GN and NiS CW, showing that NiS pcw GN has a lower ratio of D band to G band (I D /I G =1.05) compared to NiS pcw (I D /I G =1.2). 7

9 Figure S6. (b) Cyclic voltammetry (CV) curves of NiS pcw GN for the initial 3 cycles at a scan rate of 0.1 mvs -1. (b) Galvanostatic discharge-charge profiles of NiS pcw GN at various current rate. 8

10 Figure S7. The initial charge-discharge profiles of NiS pcw GN at 0.2C, showing the experimental and bulk OCV values. The bulk OCV values are obtained according to the change of Gibbs free energy. 9

11 Figure S8. Rate performance and capacity retention of NiS pcw, showing a low capacity of 306 and 116 mah g -1 at high rate of 5 and 10C, respectively. 10

12 Figure S9. (a) Reduction and (b) oxidation peak current (Ipc and Ipa) as a function of square root of scan rate corresponding to Figure 4d. 11

13 Figure S10. Cycling performance of NiS-GN at 1C, showing a rapid capacity decay for the NiS- GN electrodes with a discharge capacity of 218 mah g -1 after 150 cycles. 12

14 Figure S11. Discharge energy density of NiS pcw GN and NiS pcw as a function of cycle number. 13

15 Figure S12. SEM images of the (a,b) NiS pcw GN and (c,d) NiS pcw electrodes after 300 cycles, revealing that the multi-scale and hierarchically ordered structure is still preserved after long cycling for NiS pcw GN while partial nanowires crack into the nanoparticles after long cycling for NiS pcw. 14

16 Figure S13. Rate performance and capacity retention of CoS pcw, showing a low capacity of 314 and 150 mah g -1 at high rate of 5 and 10C, respectively. 15

17 Figure S14. Rate performance and capacity retention of CoS-GN, showing a low capacity of 151 and 38 mah g -1 at high rate of 5 and 10C, respectively. 16

18 Figure S15. The initial charge-discharge profiles of CoS pcw GN as a anode with a cut-off voltage range from to 3 V at 0.2 A g

19 Figure S16. Rate performance and capacity retention of MnS pcw, showing a reversible capacity of 757, 630, 478, 345, 195 mah g -1 at a current rate of 0.2, 0.5, 1, 2, 5 A g -1, respectively. 18

20 Figure S17. Rate performance and capacity retention of MnS-GN, showing a reversible capacity of 588, 420, 284, 138, 10 mah g -1 at a current rate of 0.2, 0.5, 1, 2, 5 A g -1, respectively. 19

21 Figure S18. Electrochemical impedance spectra of (a) the NiS pcw and NiS pcw GN electrodes, (b) the CoS pcw and CoS pcw GN electrodes, and (c) the MnS pcw and MnS pcw GN electrodes before cycling. 20