Supporting Information

Transcription

1 Supporting Information Robust Pitaya-Structured Pyrite as High Energy Density Cathode for High Rate Lithium Batteries Xijun Xu,, Jun Liu,,,* Zhengbo Liu,, Jiadong Shen,, Renzong Hu,, Jiangwen Liu,, Liuzhang Ouyang,, Lei Zhang, and Min Zhu,,* School of Materials Science and Engineering and Guangdong Provincial Key Laboratory of Advanced Energy Storage Materials, South China University of Technology, Guangzhou, , PR China China-Australia Joint Laboratory for Energy & Environmental Materials, South China University of Technology, Guangzhou, , PR China School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, , China 1

2 Figure S1. The XPS spectra of Fe 3 O (a) survey; (b) Fe 2p; (c) O 1s; (d) C 1s. 2

3 Figure S2. The XPS spectra of FeS (a) survey; (b) Fe 2p; (c) S 2p; (d) C 1s. 3

4 Figure S3. Low- and high-magnification TEM images of porous vesica-like carbon frameworks obtained via etching the inner FeS 2 nanoparticles in pitaya-structured FeS nanospheres. 4

5 Figure S4. N 2 adsorption/desorption isotherms (a) of the pitaya-structured FeS and the corresponding pore-size distribution (b) calculated using the BJH method. 5

6 Intensity (a.u.) C-3.0 V C-2.0 V C-1.5 V D-1.5 V D-1.0 V FeS 2 Li 2 S Fe 7 S 8 Li 2 FeS 2 Cu foil Theta (degree) Figure S5. The ex-situ XRD patterns of pitaya-structured pyrite at different voltages during discharge/charge processes. 6

7 Figure S6. The Fe 2p XPS spectra of FeS electrode at different discharge/charge stages: (a) before cycles; (b) discharged to 1.0 V; (c) discharged to 1.5 V; (d) charged to1.5 V; (e) charged to 2.0 V; (f) charged to 3.0 V. 7

8 Figure S7. The S 2p XPS spectra of FeS electrode at different discharge/charge stages: (a) before cycles; (b) discharged to 1.5 V; (c) discharged to 1.0 V; (d) charged to1.5 V; (e) charged to 2.0 V; (f) charged to 3.0 V. 8

9 Figure S8. Different magnification SEM images of pitaya-structured FeS cathode after 100 cycles at 0.3 A g -1 showing the encapsulated framework of particles. 9

10 Specific capacity (ma h g -1 ) ma g -1 FeS 2 nanoparticles 200 Charge 20 Discharge Cycle number Coulombic efficiency (%) Figure S9. The electrochemical performance of pure FeS 2 nanoparticles at 300 ma g

11 The calculation method of energy density and power density: Energy density = Voltage Capacity (eq. S1) Power density = Voltage Current density (eq. S2) According to the eq. S1 and S2, the energy density and power density can be calculated, respectively. In the current work of FeS electrode, the average voltage was used to replace the voltage for determining the result, and it could be got from the charge/discharge profiles. 11

12 Table S1. A comparison of rate performance between the pitaya-structured pyrite (FeS 2 ) and other reported FeS 2 -cathodes for Li-ion storage. Materials Rate (A g 1 ) Capacity (mah g 1 ) PAN-FeS (after 50 cycles) Al 2 O 3 -coated 0.2 FeS fiber (after 100 cycles) FeS 2 nanocrystals (after 100 cycles) (after 50 cycles) FeS 2 nanowires (after 50 cycles) 0.5 FeS (after 400 cycles) 1.0 FeS 2 /graphene (after 200 cycles) 0.1 FeS2@C nanowires (after 100 cycles) This work (after 100 cycles) (after 100 cycles) 12

13 Figure S10. Na-ion storage performance of pitaya-structured FeS nanospheres: (a) CV curves at a scanning rate of 0.1 mv s 1 in the voltage range of V; (b) voltage-capacity curves of pitaya-structured FeS nanospheres at 0.6 A g

14 800 -Z"(ohm) SIB LIB Z'(ohm) Figure S11. The EIS spectra of pitaya-structured FeS nanospheres for Na-ion (the black line) and Li-ion (the red line) storage. 14

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