Magnesium Hydride Nanoparticles Self-Assembled. on Graphene as Anode Material for High- Performance Lithium-Ion Batteries

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1 Supporting Information Magnesium Hydride Nanoparticles Self-Assembled on Graphene as Anode Material for High- Performance Lithium-Ion Batteries Baoping Zhang, Guanglin Xia, *, Dalin Sun, Fang Fang and Xuebin Yu * Department of Materials Science, Fudan University, Shanghai , China Institute for Superconducting and Electronic Materials, University of Wollongong, North Wollongong, NSW 2522, Australia Shanghai Innovation Institute for Materials, Shanghai , China *Corresponding Author yuxuebin@fudan.edu.cn; guanglin@uow.edu.au 1

2 Figure S1. (a, b) SEM images of the as-synthesized GMH composite. (c) The corresponding particle size distributions. Figure S2. (a) The pore-size distribution of the GMH composite and the nitrogen adsorptiondesorption isotherms in the inset. (b) TGA curve of the GMH composite. 2

3 Figure S3. The commercial MgH 2 electrode: (a, b) SEM images at different resolutions. (c) Representative CV curves at a scan rate of 0.05 mv s 1. (d) Discharge and charge voltage profiles at 100 ma g 1. (e) Rate capacities at various current rates from 100 to 2000 ma g 1. 3

4 Figure S4. The electrochemical performance of graphene electrode (GR-PMMA): (a) Cycling performances at 100 ma g 1. (b) Discharge and charge voltage profiles at 100 ma g 1. (c) Rate capacities at various current rates from 100 to 2000 ma g 1. (d) SEM images of graphene. Figure S5. XRD patterns of the mixture of MgH 2 and PVDF binder. It can be seen that the typical pattern of MgF 2 can be distinguished, which can be ascribed to the reaction between 4

5 PVDF and MgH 2, along with the dehydrogenation of MgH 2. The verified reactivity between MgH 2 and PVDF not only explains why a large of foam or bubbles generate during the fabrication of the electrode slurry of MgH 2 with PVDF binder, but also is responsible for the largely lowered discharge capacity of GMH-PVDF electrode in Figure 2a. Figure S6. Cycling performances of CMH-PMMA, GR-PMMA, and GMH-BF electrodes at a lager current density of 2000 ma g 1. 5

6 Figure S7. SEM images of GMH-65 (a, b) and GMH-80 (c, d). (e) Cycling performances of GMH-65 and GMH-80 with PMMA binder at a current density of 100 ma g 1. (f) TPD curves of GMH-65 and GMH-80 at a rate of 5 o C min -1. Figure S8. EIS of the GMH-PMMA and GMH-BF electrodes from 100 khz to 0.01 Hz after 3 cycles and 100 cycles at a current density of 100 ma g 1 as well as the corresponding simulated solid curves (insets: the equivalent circuit). 6

7 Figure S9. The particle size distributions of GMH composite after the first lithiation. Figure S10. (a, b, c) SEM images of the GMH-PMMA at discharged state after 1st, 20th, 50th cycles at 100 ma g 1. (d, e, f) SEM images of the GMH-BF at discharged state after 1st, 20th, 50th cycles at 100 ma g 1. 7

8 Figure S11. (a) STEM image of GMH-PMMA electrode after 50th cycles and the corresponding elemental mapping of C and Mg. (b) STEM image of GMH-BF electrode after 50th cycles and the corresponding elemental mapping of C and Mg. Table S1. Capacity comparisons of present works with representative MgH 2 -based electrode materials. Samples Current density Voltage window Cycle number Capacity Retention Reference MgH 2 /MCMB 0.1 C V mah g 1 (1) MgH 0.1 C V mah g 1 (2) MgH 2 /SP 100 ma g V mah g 1 (3) MgH 2 -CMC-f 0.1 C V mah g 1 (4) GMH-PMMA 100 ma g V mah g 1 this work 8

9 Table S2. The corresponding simulation values based on the equivalent circuit in Figure S8. Cycles R CT Rs W o -R W o -T W o -P CPE 1 -T CPE 1 -P GMH-PMMA E E GMH-BF E E REFERENCES (1) Oumellal, Y.; Rougier, A.; Nazri, G. A.; Tarascon, J. M.; Aymard, L. Metal Hydrides for Lithium-Ion Batteries. Nat. Mater. 2008, 7, (2) Oumellal, Y.; Zlotea, C.; Bastide, S.; Cachet-Vivier, C.; Leonel, E.; Sengmany, S.; Leroy, E.; Aymard, L.; Bonnet, J.-P.; Latroche, M. Bottom-Up Preparation of MgH 2 Nanoparticles with Enhanced Cycle Life Stability during Electrochemical Conversion in Li-Ion Batteries. Nanoscale 2014, 6, (3) Brutti, S.; Mulas, G.; Piciollo, E.; Panero, S.; Reale, P. Magnesium Hydride as a High Capacity Negative Electrode for Lithium Ion Batteries. J. Mater. Chem. 2012, 22, (4) Zaidi, W.; Oumellal, Y.; Bonnet, J. P.; Zhang, J.; Cuevas, F.; Latroche, M.; Bobet, J. L.; Aymard, L. Carboxymethylcellulose and Carboxymethylcellulose-Formate as Binders in MgH 2 - Carbon Composites Negative Electrode for Lithium-Ion Batteries. J. Power Sources 2011, 196,