Supporting Information for

Transcription

1 Supporting Information for Designing Air-Stable O3-Type Cathode Materials by Combined Structure Modulation for Na-Ion Batteries Hu-Rong Yao,, Peng-Fei Wang,, Yue Gong, Jienan Zhang, Xiqian Yu, Lin Gu,, Chuying OuYang, Ya-Xia Yin,, Enyuan Hu, # Xiao-Qing Yang, # Eli Stavitski, # Yu-Guo Guo,*,, Li-Jun Wan,, 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 , China Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, CAS, Beijing , China Laboratory of Computation Materials Physics, Department of Physics, Jiangxi Normal University, Nanchang, , China University of Chinese Academy of Sciences, Beijing , China # Brookhaven National Laboratory, Upton, New York 11973, USA Corresponding Author: * ygguo@iccas.ac.cn Experimental Details. DFT calculations. The DFT calculations were performed to simulate thermodynamic effect of foreign atoms substation with the Vienna ab initio simulation package (VASP) 1. The projector augmented wave (PAW) 2 method and generalized gradient approximation (GGA) with Perdew Burke Ernzerhof (PBE) 3 functional and GGA+U extension were used. The applied effective U value given to Ni ions was 6.1 ev, to Cu ions was 7.2 ev, to Mn ions was 4.0 ev, and to Ti ions was 3.4 ev 4. The energy cutoff for the plane-wave basis set was 520 ev and the force convergence criterion for the relaxation was 0.01 ev Å 1. The Monkhorst-Pack 5 scheme k-point sampling was used, and k-mesh was denser than 0.03 Å 1. The simulations of the bulk structure were performed on the supercell including 12 formula units with 6 Mn ions (48 atoms in total). To simulate Ti doping bulk structure, one of Mn ions was substituted with Ti ion. S-1

2 Synthesis. The solid-state method was used for the preparation of O3-NaNi 0.5-x Cu x Mn 0.5-y Ti y O 2 (x = 0, 0.05; y = 0, 0.1) materials mentioned in this article. The mixing of stoichiometric values of Na 2 CO 3 (Alfa-Aesar Co., 99.5%), NiO (Alfa-Aesar Co.,99%), CuO (Sinopharm Chemical Reagent Co., Ltd. 98%), Mn 2 O 3 (Alfa-Aesar Co., 98%), and TiO 2 (Alfa-Aesar Co., 99.9%) were ground in an agate mortar and pressed into pellets under a pressure load of 10 MPa. Owing to the sodium volatility in high temperature, an access 5mol% of Na 2 CO 3 is added. The precursors were followed by calcination at 1000 C for 12 h in air to obtain the target compounds. Characterizations. SEM measurements were performed on a JEOL 6701F apparatus (10 kv). The shown XRD patterns were all collected by D8 Advance diffractometer (Bruke) with Cu K α radiation. Rietveld refinement for crystal structures were carried out by using GSAS software. For in-situ XRD experiment, a special cell was assembled with Al foil as both current collector and X-ray window. The EDS maps were obtained with TEM (JEM 2100F). The XPS of the samples were carried out on the ESCALab 250Xi (Thermo Scientific) spectrometer equipped with an Al K α achromatic X-ray source. The ex-situ XANES data at Ni and Mn K-edges were recorded in transmission mode at beam line BL14W1 of the Shanghai Synchrotron Radiation Facility (SSRF, China) and beamline 8-ID of the National Synchrotron Light Source II (NSLS II, BNL). The X-ray absorption near-edge spectroscopy data were normalized and removed background by using the program IFEFFIT. HAADF and ABF STEM imaging was executed using a JEM-ARM200CF (JEOL, Tokyo, Japan) equipped with cold emission gun and double hexapole Cs corrector (CEOS GmbH, Heidelberg, Germany), operated at 200 kv. The attainable spatial resolution is 78 pm. Electrochemistry. The electrochemical performances were evaluated in Na half cells with porous glass fiber as separator. The cathodes were prepared by mixing active material, Super P carbon and poly(vinyl difluoride) binder in a weight ratio of 7:2:1 onto Al foil, and dried at 80 C in vacuum overnight. The loading mass of active material in the cathode was about 3 mg cm 2. The coin cells were assembled in an Ar-filled glove box (H 2 O, O ppm) with a solution of 1 M NaClO 4 in propylene carbonate (PC, 5% FEC) as electrolyte. The cells were charged/discharged on Land BT2000 battery test system between a voltage range of V vs. Na + /Na at room temperature. S-2

3 Figure S1. (a) Rietveld refinement pattern of the power XRD data for NaNMT; (b) Comparison of refined structures of NaNM and NaNMT. S-3

4 Figure S2. Comparison of XPS spectra of NaNM and NaNCMT for Ni 2p region. S-4

5 Figure S3. (a) SEM image and (b) EDS maps of NaNM. S-5

6 Figure S4. Comparison of refined structures of NaNM and NaNCMT. S-6

7 Figure S5. Comparison of powder XRD patterns of as-synthesized NaNM and the one after 2 hours of air exposure. S-7

8 Figure S6. Comparison of powder XRD patterns of as-synthesized NaNM and the one after 10 min of soak in water. S-8

9 Figure S7. SEM image of water-soaked NaNCMT. S-9

10 Figure S8. The second galvanostatic charge and discharge curves of as-synthesized, air-exposed and water-soaked NaNM. S-10

11 Figure S9. Comparison of XRD patterns of as-synthesized, air-exposed and water-soaked NaNCMS. Blue asterisks represent peaks from CuO. S-11

12 Table S1. Crystallographic parameters of O3-NaNMT refined by the Rietveld method. Space group Atom R-3m (No. 166) site x y z occ Na 3a Ni 3b Mn 3b Ti 3b O 6c a = (5) Å c = (7) Å R p = 4.62% R wp = 5.86% Table S2. Crystallographic parameters of O3-NaNM refined by the Rietveld method. Space group Atom R-3m (No. 166) site x y z occ Na 3a Ni 3b Mn 3b O 6c a = (4) Å c = (4) Å R p = 4.98% R wp = 6.81% Table S3. Crystallographic parameters of O3-NaNCMT refined by the Rietveld method. Space group Atom R-3m (No. 166) site x y z occ Na 3a Ni 3b Cu 3b Mn 3b Ti 3b O 6c a = (3) Å c = (8) Å R p = 4.13% R wp = 5.42% S-12

13 Supplementary References (1) Kresse, G.; Hafner, J. Phys. Rev. B 1993, 48, (2) Blöchl, P. E. Phys. Rev. B 1994, 50, (3) Perdew, J. P.; Burke, K.; Ernzerhof, M. Phys. Rev. Lett. 1996, 77, (4) Yang, M. C.; Xu, B.; Cheng, J. H.; Pan, C. J.; Hwang, B. J.; Meng, Y. S. Chem. Mater. 2011, 23, (5) Monkhorst, H. J.; Pack, J. D. Phys. Rev. B 1976, 13, S-13