Supporting Information for Honeycomb-Ordered Na 3 Ni 1.5 M 0.5 BiO 6 (M = Ni, Cu, Mg, Zn) as High Voltage Layered Cathodes for Sodium-Ion Batteries Peng-Fei Wang, a,d, Yu-Jie Guo, a,d, Hui Duan, a,d Tong-Tong Zuo, a,d Enyuan Hu, e Klaus Attenkofer, e Hongliang Li, c Xiu Song Zhao, c Ya-Xia Yin, a,d, * Xiqian Yu b, * and Yu-Guo Guo a,d, * a CAS Key Laboratory of Molecular Nanostructure and Nanotechnology CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100190, China b Beijing National Laboratory for Condensed Matter Physics Institute of Physics, Chinese Academy of Sciences (CAS) Beijing 100190, China c Institute of Materials for Energy and Environment, Laboratory of New Fiber Materials and Modern Textile, Growing Basis for State Key Laboratory, College of Materials Science and Engineering, Qingdao University Qingdao 266071, China d University of Chinese Academy of Sciences, Beijing 100049, China e Brookhaven National Laboratory, Upton, New York 11973, USA S-1
These authors contributed equally to this work. * To whom correspondence should be addressed. E-mail: ygguo@iccas.ac.cn; yxyin@iccas.ac.cn; xyu@iphy.ac.cn S-2
Experimental Section Materials synthesis. Na 3 Ni 1.5 M 0.5 BiO 6 (M = Ni, Cu, Mg, Zn) samples were synthesized by a facile solid state method. Stoichiometric Na 2 CO 3 (3% excess) and NaBiO 3 with NiO, CuO, Mg(OH) 2, or ZnO, respectively, were first ground using a mortar. The Ni/Zn/Cu samples were pressed into 13 mm diameter pellets and calcined at 700 C for 8 h under flowing O2, then reground, and recalcined to 750 C as a loose powder for extra 12 h. The Mg sample was heated as a loose powder at 700 C for 20 h under flowing O2, reground, and reheated to 750 C for another 12 h, all samples were kept in an Ar-filled glove box until use. Materials characterization. Powder X-ray diffraction patterns was carried out using a D8 Bruker Advance diffractometer equipped with Cu Kα radiation source (λ = 1.5418 Å). XRD diffraction was then refined using the General Structure Analysis System (GSAS) program based on Rietveld method. A scanning electron microscopy (JEOL 6701F) operated at 10 kv was used to visualize the morphologies of the materials. HRTEM images, SAED patterns and EDS maps are obtained using JEM 2100F electron microscope operated at 200 kv. The XPS data were obtained with an ESCALab 250Xi (Thermo Scientific) spectrometer equipped with an Al Kα radiation. The ex situ XAS data at the Ni and Cu K-edge were recorded at room temperature in transmission mode at beamline 8-ID of the National Synchrotron Light Source II (NSLS II, BNL). The photon energy was calibrated with the first inflection point of Ni and Cu K-edges in the relevant metal foil. The electrode samples with different charged and discharged states were sealed with Kapton tape in the Ar-filled glove box. The XAS spectra were normalized and removed background with the program IFEFFIT. Electrochemical measurements. Electrochemical tests of the samples were conducted in 2032 coin cells assembled in an argon-filled glove box (H 2 O, O 2 0.1 ppm). The working S-3
electrode was mixed with 70 wt% the active material, 20 wt% Super P carbon black, and 10 wt% poly(vinyl difluoride) (PVDF, Aldrich). The electrolyte 1 M NaClO 4 in the mixture of propylene carbonate (PC) (5% FEC). A porous glass fiber (GF/D) was used as the separator and Na metal as the counter electrode. Galvanostatic tests were performed on an Arbin BT2000 system at 25 C. Cyclic voltammetry tests were conducted an Autolab PG302N electrochemical workstation at a scan rate of 0.1 mv s 1. Calculation of apparent Na + chemical diffusion coefficients through CV results. The Na + apparent diffusion coefficient can be calculated according to the following equation: I p = 0.4463n 3/2 F 3/2 CSR -1/2 T -1/2 D 1/2 v 1/2 where I p (A) is peak current, n is the charge transfer number, F is Faraday constant (96485 C mol -1 ), S (cm 2 ) is the area of the electrode, C (mol cm -3 ) is the inserted Na + concentration in Na 3 Ni 1.5 M 0.5 BiO 6, T (K) is the absolute temperature, R is the gas constant (8.314 J mol 1 K 1 ), v (V s -1 ) is the scan rate, D (cm 2 s -1 ) is the Na + diffusion coefficient. S-4
Figure S1. Rietveld refinement patterns of the power XRD data for Na 3 Ni 1.5 Mg 0.5 BiO 6. S-5
Figure S2. Rietveld refinement patterns of the power XRD data for Na 3 Ni 1.5 Zn 0.5 BiO 6. S-6
Figure S3. SEM images of Na 3 Ni 1.5 M 0.5 BiO 6 : (a) M = Ni, (b) M = Cu, (c) M = Mg, and (d) M = Zn. S-7
Figure S4. HRTEM image of Na 3 Ni 2 BiO 6. The inset shows the d-spacing of the (1 1 1) plane. S-8
Figure S5. TEM image and EDS maps of Na 3 Ni 2 BiO 6 samples, demonstrating an even distribution of sodium, nickel, bismuth and oxygen elements in sample particles. S-9
Figure S6. Cyclic voltammograms at various sweep rates for (a) Na 3 Ni 2 BiO 6 and (b) Na 3 Ni 1.5 Cu 0.5 BiO 6 electrodes. S-10
Figure S7. Corresponding peak current I p as a function of square root of scan rate v 1/2 for (a) Na 3 Ni 2 BiO 6 and (b) Na 3 Ni 1.5 Cu 0.5 BiO 6 electrodes, respectively. S-11
Figure S8. XPS spectra of Na 3 Ni 1.5 M 0.5 BiO 6 (M = Ni, Cu, Mg and Zn) for (a) Na1s, (b) Ni2p (c) Bi4f, (d) Cu2p, (e) Mg1s and (f) Zn2p regions. S-12
Figure S9. Local structure of (a) Na 3 Ni 2 BiO 6 and (b) Na 3 Ni 1.5 M 0.5 BiO 6 (M = Cu, Mg and Zn) within the oxygen layers. S-13
Table S1. Structural parameters of Na 3 Ni 2 BiO 6 refined by the Rietveld method. Atom Site x y z Occ. Na(1) 2d 0 0.5 0.5 1 Na(2) 4h 0.5 0.3558(3) 0.5 1 O(1) 8j 0.2435(9) 0.8450(8) 0.2193(6) 1 O(2) 4i 0.2268(8) 0.5 0.2092(8) 1 Bi(1) 2a 0 0 0 0.6382 Ni(2) 2a 0 0 0 0.3618 Ni(1) 4g 0 2/3 0 0.8191 Bi(2) 4g 0 2/3 0 0.1809 S.G. C2/m R p = 5.91 % R wp = 8.78 % S-14
Table S2. Structural parameters of Na 3 Ni 1.5 Cu 0.5 BiO 6 refined by the Rietveld method. Atom Site x y z Occ. Na(1) 2d 0 0.5 0.5 1 Na(2) 4h 0.5 0.3562(4) 0.5 1 O(1) 8j 0.2449(5) 0.8467(0) 0.2233(8) 1 O(2) 4i 0.2357(5) 0.5 0.2126(7) 1 Bi(1) 2a 0 0 0 0.6382 Ni(2) 2a 0 0 0 0.2713 Cu(2) 2a 0 0 0 0.0904 Ni(1) 4g 0 2/3 0 0.6144 Cu(1) 4g 0 2/3 0 0.2048 Bi(2) 4g 0 2/3 0 0.1809 S.G. C2/m R p = 5.65 % R wp = 8.39 % S-15
Table S3. Lattice parameters of Na 3 Ni 1.5 M 0.5 BiO 6 (M = Ni, Cu, Mg, Zn) in C2/m space group. Na 3 Ni 2 BiO 6 Na 3 Ni 1.5 Cu 0.5 BiO 6 Na 3 Ni 1.5 Mg 0.5 BiO 6 Na 3 Ni 1.5 Zn 0.5 BiO 6 a (Å) 5.4022(8) 5.4140(7) 5.4089(6) 5.4157(3) b (Å) 9.3530(4) 9.3582(3) 9.3646(6) 9.3795(3) c (Å) 5.6821(0) 5.6925(8) 5.6921(9) 5.6896(9) β ( ) 108.51(0) 108.60(8) 108.39(1) 108.39(2) V (Å 3 ) 272.25(1) 273.34(4) 273.60(1) 274.25(6) S-16
Table S4. Atomic distances, slab thickness (MO 2 ), d-spacing and the interslab distance for asprepared materials. Samples Na 3 Ni 2 BiO 6 Na 3 Ni 1.5 Cu 0.5 BiO 6 M O (Å) 2.1613(3) 2.1856(7) MO 2 (Å) 2.3088(2) 2.3524(9) d-spacing (Å) 3.0793(3) 3.0425(0) interslab distance (Å) 5.3881(5) 5.3949(9) S-17