Nanoscale

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This journal is © The Royal Society of Chemistry [year] [journal], [year], [vol], 00–00 |1

Encapsulation of Nanoscale Metal Oxides into Ultra-thin Ni Matrix for Superior Li-Ion Batteries: A Versatile Strategy Jianhui Zhu,a, b Jian Jiang,a, b Wei Ai,a Zhanxi Fan,c Xintang Huang,b Hua Zhangc and Ting Yu*a, d 5

aDivision of Physics and Applied Physics, School of Physical andMathematical Sciences, Nanyang Technological

University, 637371, Singapore. E-mail: YuTing@ntu.edu.sg; 10 bInstitute of Nanoscience and Nanotechnology, Department of Physics, Central China Normal University,

Wuhan, 430079, Hubei, P.R. China. cSchool of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore; dGraphene Research Centre, National University of Singapore, 117546, Singapore.

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1. Experimental Details: 1.1 Preparation of Ni(OH)2 film: 0.3g Ni(NO3)2·6H2O and 0.7g hexamethylenetetramine (HMT) were dissolved in 50 mL distilled water. After 30 min ultrasonication treatment, the transparent suspension was then 20

transferred into a sealed container (80 mL) and held at 95 oC for 6 h. The pure Ni(OH)2 films can be harvested

after wash for several times.

1.2 Preparation of Fe3O4@Ni hybrids: Single-crystalline Fe3O4 hexagonal nanoplates were synthesized by

referring to the previous work.17 In brief, a green mixture of FeSO4·7H2O (0.4 g), NaOH (0.53 g), ethylene

glycol (45 mL) and distilled water (15 mL) was treated by ultrasonication for 30 min, transferred into a Teflon-25

lined stainless steel autoclave and held at 95 oC for 20 h. The as-formed Fe3O4 precipitation was then washed,

dried and collected as raw materials for later fabrication. In typical synthesis of Fe3O4@Ni hybrids, 0.15 g Fe3O4

nanoplates, 0.7 g HMT, 0.3 g Ni(NO3)2·6H2O and 50 mL distilled water were mixed and dissolved by

ultrasonication for 15 min. The obtained suspension was then transferred into a sealed container (80 mL) and

held at 95 oC for 6 h. Later, the Fe3O4@Ni(OH)2 intermediate was collected and washed by distilled water 30

several times. The reduction procedure was performed in a horizontal, quartz tube-furnace system. 0.3 g

Fe3O4@Ni(OH)2 (pre-dispersed into 10 ml distilled water, dropped onto a ceramic wafer and dried at 60 oC)

were placed into the centre of a quartz tube (tube diameter: 2 inch). 1.5 mL of ethylene glycol (EG) loaded in an

alumina boat was put at the upstream zone of quartz tube. Before heating, the tube reactor was sealed and

flushed by Ar gas (200 sccm) for 10 min. The furnace was then heated to 610±10K at a heating rate of ~10 K 35

min-1 under a constant Ar flow of 80 sccm, kept for 15 min and allowed to cool down to room temperature

naturally.

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