Stabilizing the Interface of NASICON Solid Electrolyte against Li Metal with Atomic Layer Deposition

Transcription

1 Supporting Information Stabilizing the Interface of NASICON Solid Electrolyte against Li Metal with Atomic Layer Deposition Yulong Liu,, Qian Sun,, Yang Zhao, Biqiong Wang, Payam Kaghazchi, Keegan R. Adair, Ruying Li, Cheng Zhang #, Jingru Liu #, Liang-Yin Kuo, Yongfeng Hu, Tsun-Kong Sham, Li Zhang, Rong Yang, Shigang Lu, Xiping Song #, *, Xueliang Sun, * Department of Mechanical and Materials Engineering, Western University, London, Ontario, N6A 5B9, Canada Physikalische und Theoretische Chemie, Freie Universitat Berlin, D Berlin, Germany. # State Key Laboratory for Advance Metal and Materials, University of Science and Technology Beijing, Beijing , China Canadian Light Source, Saskatoon S7N 2V3, Canada Department of Chemistry, Western University, London, Ontario, N6A 3K7, Canada. China Automotive Battery Research Institute Co., Ltd, Beijing, , China Equally contributed * Corresponding author xsun9@uwo.ca and xpsong@skl.ustb.edu.cn S-1

2 Experimental section Synthesis of LATP. The base materials for Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP) synthesis were Li 2 CO 3 (Sigma-Aldrich), (C 4 H 9 O) 4 Ti (Sigma-Aldrich), Al(OH) 3 (Sigma-Aldrich), NH 4 H 2 PO 4 (Sigma- Aldrich), and it was synthesized through a wet-chemical method. The raw sources were weighted according to the stoichiometry of Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3, with 10 wt.% Li 2 CO 3 excess. The Ti source was first dissolved into water by the addition of HNO 3 solution, which was labeled as solution A. Then, the Li, Al, and P sources were dissolved into distilled water, which was labeled as solution B. After this, we added solution A into B dropwise under strong stirring. After about 1h, PVA as the entrapping agent to absorb the cations in the solutions on the polymer chains were dissolved in the solution. After the evaporation of the water, the solution ended up with a white gel. After heating the gel at 500 C for 2h, the residual organic compounds were combusted and the precursors were obtained after the decomposition of base materials. The precursors were calcined in a muffle furnace at 700 C for 2 hours, and crystalline LATP powders were obtained. The powder was then pelletized into 12.7 mm and 1.5 mm pellets before sintered them in the furnace at 1000 C for 2 h. The sintered LATP pellets were polished with sand paper (from 180 down to 2000 mesh) and washed with ethanol before use. ALD coating on LATP. The Al 2 O 3 ALD coating were conducted on Gemstar-8 ALD system (Arradiance, USA) which was connected to an argon filled glove box. Al 2 O 3 was directly deposited on the LATP pellet at 85 C by using trimethylaluminum and water as precursors. A fresh Li foil was also coated with ALD, and 75 cycles Al 2 O 3 were coated and named Li@75 Al 2 O 3. The Li 3 PO 4 ALD coating was deposited on the LATP pellet in a Savannah 100 ALD system (Ultratech/Cambridge Nanotech., USA). The Li 3 PO 4 was deposited by using LiO t Bu [(CH 3 ) 3 COLi] and TMPO [(MeO) 3 PO] as the precursors, source temperature for LiO t Bu and TMPO were 180 C and 75 C, respectively. The deposition temperature of Li 3 PO 4 was carried out at 250 C. The sample with different cycle numbers of 25, 50, 100, 150, 200, 250 ALD Al 2 O 3 coating on LATP were named as LATP@25 Al 2 O 3, LATP@50Al 2 O 3, LATP@100Al 2 O 3, LATP@150Al 2 O 3, LATP@200Al 2 O 3, LATP@250Al 2 O 3, respectively. 175 cycle of Li 3 PO 4 deposited on the LATP was named as LATP@175 Li 3 PO 4, the coating layer had close thickness with LATP@150Al 2 O 3. Electrochemical tests: To measure the ionic conductivity of the LATP solid state electrolyte, Au coated was sputtered on the both sides of the ceramic disc and acted as a blocking electrode. The S-2

3 electrochemical cycle of LATP pellets was evaluated in CR2032 coin-type cells. Typically, the coin cells were assembled in an ultra-pure argon filled glove box by symmetrical Li/LATP/Li configuration by pressing them with hydraulic press (MTI). The Li stripping/plating studies were carried out in an Arbin BT-2000 Battery Test system at room temperature. Constant current densities were applied to the cells during repeating stripping/platting while the potential was recorded over time. Electrochemical impedance spectroscopy (EIS) was performed on the versatile multichannel potentiostat 3/Z (VMP3). Characterization. The morphology and structure of the LATP cross-sections were characterized by using Hitachi 4800 Field emission Scanning Electron Microscopy at an acceleration voltage of 5 kv. The High-energy x-ray photoelectron spectroscopy (HE- XPS) at Ti 2p was conducted at Soft X-ray Micro- characterization Beamline (SXRMB), Canadian Light Source, located at the University of Saskatoon, Saskatoon, Canada. The detection depth of HE-XPS was adjusted by tuning the photon energy from 3 to 6 kev. The interface of LATP samples was cut by focused ion beam (FIB, Zeiss Auriga Gemini) into slices, and the slice was mounted to a Cu grid for further TEM observation. The slices were subjected to high resolution transmission electron microscope(hrtem, Titan G ) equipped with EDAX detectors of ChemiStem Technology at an acceleration voltage of 300 kv to identify the morphology and chemical information. The EELS line and mapping are obtained on the JEM-ARM200F with acceleration voltage of 200 kv. Simulation. Density functional theory (DFT) calculations were carried out using the projectoraugmented plane-wave (PAW) method as implemented in the Vienna Ab Initio Simulation Package (VASP). 1 The Perdew Burke Ernzerhof (PBE) functional was applied. 2 Bulk LATP was modelled using Li 1.33 Al 0.33 Ti 1.67 (PO 4 ) 3 (8 Li, 2 Al, 10 Ti, 18 P, and 72 O) with a (R-3CH) structure and a 1 1 1unit cell. Bulk -Al 2 O 3 was modelled using a (R-3CH) structure with a unit cell. Bulk Li metal was modelled using the bcc structure with a conventional unit cell. A Monkhorst-Pack k-point mesh of 3 3 1, 6 6 2, and was used for LATP, - Al 2 O 3, and Li, respectively. An energy cutoff of 450 ev and an energy convergence criterion of 10-4 ev were used for all systems. To find the most favourable site for Li binding we have checked four and six possible interstitial sites in LATP and -Al 2 O 3, respectively. The calculated unit cells and corresponding experimental values are listed in Table S4. The XRD pattern was S-3

4 simulated by computing structure factor of reflection for the fully relaxed pristine LATP using the software VESTA in which scattering parameters are based on tabulated values. 3-6 S-4

5 Figure S1: LATP solid state electrolyte. (a) XRD pattern, (b) RT Nyquist plot of LATP after sintering, (c) Arrhenius plot of LATP electrolyte. (d) Voltage(V) Time (s) Figure S2: Impedance of LATP/Li symmetrical cells before cycling and after the 300 th cycle. (a) Bare LATP, (b) LATP@ 150 Al 2 O 3, (c) LATP@175 Li 3 PO 4, (d) Cycling performance of Li/LATP/Li at 55 C. S-5

6 Figure S3: Different lithiation mechanism of 150 Al 2 O 3 and LATP@175 Li 3 PO 4 Table S1: Summary of the impedance data of LATP/Li symmetrical cells Impedance LATP LATP@150 Al 2 O 3 LATP@175 Li 3 PO 4 (ohm) First cycle 6 K 8M 10K 300th cycle 400 K 150 K 350K S-6

7 Figure S4: Electrochemical behavior of the 250 (a), 200 (b), 150 (c), 100 (d), 50(e), 25 (f) Al 2 O 3 ALD coated LATP/Li symmetrical cells at a current density of 0.01 ma cm-2, each cycle take 2h for lithium stripping and plating. Figure S5: Voltage profile of the 250 (a), 200 (b), 150 (c), 100 (d), 50(e), 25 (f) Al 2 O 3 ALD coated LATP/Li symmetrical cells at first, 100th, 200th and 300th cycle. S-7

8 Figure S6: Impedance of Al 2 O 3 /Li symmetrical cells with different thickness ALD before (a) and after cycle (b). Samples: LATP@ 50Al 2 O 3, LATP@ 100Al 2 O 3, LATP@ 150Al 2 O 3, LATP@ 200Al 2 O 3 Table S2: Summary of the impedance data of LATP/Li symmetrical cells Impedance 50C 100C 150C 200C Al2O3 Al2O3 Al2O3 Al2O3 First cycle 300th cycle 1.5 M 4 M 8M 10 M 210k 220K 150K 220K S-8

9 Figure S7: Electrochemical behavior of the Al 2 O 3 ALD coated on Li for LATP/Li symmetrical cells at a current density of 0.01 ma cm -2, each cycle take 2h for lithium stripping and plating.(a) 75Al 2 O 3 ALD on Li and 75Al 2 O 3 ALD on LATP, and (b) 75Al 2 O 3 ALD on Li. Figure S8: Secondary electron images of LATP pellets after 100th cycle. bare LATP, LATP@ 175Li 3 PO 4, LATP@150Al 2 O 3 Table S3. Ti 2p XPS data of LATP before and after cycle Sample Kinetic energy Ti4+ Ti3+ LATP-fresh % 5% % 3% % 0% LATP cycled % 25% % 24% % 14% LATP@Li 3 PO 4 cycled % 27% S-9

10 % 0% % 0% Figure S9. GIXRD pattern for Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 before and after contact with Li metal. S-10

11 Figure S10. XRD pattern for Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 after long term cycle. S-11

12 Figure S11. Cycling performance of 3. Table S4. Calculated lattice parameters of LATP, -Al 2 O 3, and Li. Experimental values are given for comparison. a [Å] b [Å] c [Å] Pristine LATP Pristine LATP (exp. 8 ) Li/LATP Pristine α-al 2 O Pristine α-al 2 O 3 (exp. 9 ) Li/α-Al 2 O LATP with Al Ti substitution α-al 2 O 3 with Ti Al substitution Li metal Li metal (exp. 10 ) S-12

13 Figure S12. Simulated XRD pattern for Li 1.33 Al 0.33 Ti 1.67 (PO 4 ) 3 (8 Li, 2 Al, 10 Ti, 18 P, and 72 O) with a (R-3CH) structure. Reference: (1) Kresse G.; Furthmüller J. Efficient Iterative Schemes for Ab Initio Total-Energy Calculations Using a Plane-Wave Basis Set. Phys. Rev. B 1996, 54, (2) Perdew J. P.; Burke K.; Ernzerhof M. Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 1996, 77, (3) Momma K.; Izumi F. Vesta 3 for Three-Dimensional Visualization of Crystal, Volumetric and Morphology Data. J. Appl. Crystallogr. 2011, 44, (4) Waasmaier, D.; Kirfel, A. Acta Crystallographica Section A: Foundations of Crystallography 1995, 51, (5) Chantler C. T. Detailed Tabulation of Atomic Form Factors, Photoelectric Absorption and Scattering Cross Section, and Mass Attenuation Coefficients in the Vicinity of Absorption Edges in the Soft X-Ray (Z= 30 36, Z= 60 89, E= 0.1 Kev 10 Kev), Addressing Convergence Issues of Earlier Work. J. Phys. Chem. Ref. Data 2000, 29, (6) Berant Z.; Moreh R.; Kahane S. Nuclear Thomson Scattering of Mev Photons. Phys. Lett. B 1977, 69, S-13