Supporting Information

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1 Supporting Information Uniform Nickel Vanadate (Ni3V2O8) Nanowire Arrays Organized by Ultrathin Nanosheets with Enhanced Lithium Storage Properties Chang Wang 1, Dong Fang 1,*, Hong en Wang 2, Yunhe Cao 1, Zhiping Luo 3, Xiaoqing Liu 2, Guangzhong Li 4, Ming Jiang 1, Chuanxi Xiong 1, Weilin Xu 1,* (11) (4) (-311) (2) (-25) (-63) (-712) NH 4 V 4 O 1 (-225) As-prepared V Ni Intensity (a.u.) (131) (221) (24) (115) (244) 3 C 5 C O Ni 3 V 2 O 8 JCPDS: Y ( o ) Z X Figure S1. XRD patterns of NH4V4O1 nanowires and Ni3V2O8 nanowires (annealing at different temperatures); and structural model of orthorhombic Ni3V2O8. The crystallite sizes (D) were evaluated by the classical Scherrer equation (Equation S1), 1 the orthorhombic crystallite size (D) of Ni3V2O8 nanowire arrays annealed at various temperatures was calculated from the X-ray diffraction peaks related to (221), (24) and (244) planes using the Scherrer equation (Equation (2)). [1] D k / β cos (1) D k / (β cos ) (2) Where k is a shape constant, equal to.9, is the wavelength of the X-rays source used (Cu Kα=.1546 nm), and and are Full width at half maximum (FWHM) and peak position (radians), respectively, determined after Voigt fitting. The results are presented in Table 1. It is evidenced the effect of annealing temperature for crystallite size of Ni3V2O8. Overall, the crystallite size increases with the annealing temperature increases. S1

2 Ni 2p3 O1s Ni 2p3 Intensity (a.u.) V2p C1s Intensity (a.u.) O1s V2p C1s As-prepared material 3 O C Bindering Energy (ev) Bindering Energy (ev) Intensity (a.u.) Ni 2p Ni 2+ Ni 3+ 2p 3/ ev 2p 1/ ev 2p 3/2 2p 1/2 statellite line statellite line Intensity(a.u.) V 2p V 4+ 2p V 5+ 2p V 4+ V Bindering Energy (ev) Bindering Energy (ev) Figure S2. XPS spectra of survey spectrum from as-prepared Ni3V2O8 nanowire arrays and that after annealing at 3 C ; and the peak deconvolution and fittings of the Ni 2p and V 2p. S2

3 5 m 5 m 75 nm 13 nm min 5 nm 1 min 1 m 5 m 5 m 26 nm 321 nm 1 min 1 m 2 h 1 m (e) NH4V4O1 Ni3V2O8 min 1 min 1 min 2 h Figure S3. the samples obtained by a second hydrothermal reaction of vanadate ammonia and nickel salt with different reaction time: min, 1 min, 1 min and 2 h. S3

4 .5 m 2 μm 1 nm (e) 5 nm 1 nm (f).15 nm 21/nm 2 nm 5 nm Figure S4. Typical FE-SEM images of the Ni3V2O8 nanowire arrays with 3 C heat treatment at different magnifications. Scale bars, 2 μm; 5 nm; 2 nm; and (e) TEM images of Ni3V2O8 nanowire arrays (3 C) detached from Ti foil, and (f) HR-TEM image (inset: SAED pattern). S4

5 2 μm 5 nm 5 μm 2 μm Figure S5. Typical FE-SEM images of the Ni3V2O8 nanowire arrays growing on Ti foil with 5 C heat treatment at different magnifications: a) and b) top-view; c) and d) cross-section view. S5

6 (a ) 2 min 2 m 5 nm (b ) 4 min 2 m 1 m (c ) 6 min 3 m 1 m (d ) 2 h 2 m 5 nm (e) Figure S6. The morphology evolution of Ni3V2O8 nanowire composed by nanosheets S6

7 with increasing the reaction time at 5 ºC..4 1 Current(mA) Current(mA) st 1 cycle nd 2 cycle rd 3 cycle st 1 cycle nd 2 cycle rd 3 cycle Voltage(V) Voltage(V) Current (ma) st 1 cycle nd 2 cycle rd 3 cycle Voltage (V) 3 4 Figure S7. - show plots of the initial three the cyclic voltammogram (CV) curves at.1 mv s-1: NH4V4O1 nanowire arrays; the as-prepared Ni3V2O8 nanowire arrays; and Ni3V2O8 nanowire arrays after annealing at 3 C. S7

8 Specific Capacility (mahg -1 ) C Discharge Charge As-prepared 3 C Specific Capacility (mahg -1 ) Cycle numbers Charge of Ni 3 V 2 O 8 grown on Ti foil Discharge of Ni 3 V 2 O 8 grown on Ti foil Charge of Ni 8 3 V 2 O 8 pasted on Ti foil Discharge of Ni 3 V 2 O 8 pasted on Ti foil Cycle numbers Specific Capacility (mahg -1 ) Li + Li + Li + Li + Ti e - e - e - e - Discharge Charge Figure S8. Cycling performances of Ni3V2O8 nanowire arrays electrodes calcinated at different temperatures at 3 ma g -1 ; Cycling performances of Ni3V2O8 nanowire arrays grown or pasted on the Ti foil at 3 ma g -1 ; Nyquist plots of Ni3V2O8 nanowire arrays in the frequency range from 5 khz to.1 Hz, and the inset is the equivalent circuit; and Schematic of charge storage of the Ni3V2O8 nanowire array in LIBs. S8

9 .6 st 1 cycle nd 2 cycle rd 3 cycle 2.5. Voltage (V) Current (ma) st 1 cycle nd 2 cycle rd 3 cycle Discharge specific capacity Charge specific capacity Coulombic efficiency Cycle numbers Discharge specific capacity Charge specific capacity Coulombic efficiency Coulombic Efficiency (%) Capacity (mahg ) Specific Capacity (mah g ) Coulombic Efficiency (%) Specific Capacity (mah g ) Voltage (V) Cycle numbers 4 5 Figure S9. Electrochemical lithium storage properties of Ni3V2O8 nanowire arrays grown on Ti foil between V: the CV curves at a scan rate of.1 mv s-1; the initial three charge/discharge voltage profiles at a constant current density of 5 ma g-1; and the cycling performance at a current density of 5 ma g-1 or 5 ma g-1. 2 m 1 m Figure S1. SEM images of the Ni3V2O8 electrode after 5 cycles at a charge/discharge current of 5 ma g-1. S9

10 Table S1. Structure parameters of Ni3V2O8 nanowire arrays after annealing at different temperatures 2θ (º) FWHM Crystallite size (nm) d space Phase Room Temperature (25 ºC) ºC ºC Table S2. Electrode resistances for Ni3V2O8 nanowire arrays grown or pasted on Ti file obtained from equivalent circuit fitting of EIS results Ni3V2O8 nanowire arrays Ni3V2O8 nanowire powder Rs (Ω) Rp (Ω) CPE(Yo) (μmh) W (μmh) [1] P. Soudan, J.P. Pereira-Ramos, G. Gregoire, N. Baffier, The sol-gel mixed oxide Cr. 11V 2O 5. 16: An attractive cathodic material for secondary lithium batteries. Ionics, 1997, 3(3-4): S1