Electron crystallography for lithium based battery materials

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This lecture was given at the IUCr (International Union of Crystallography) meeting in Madrid, 2011. Contents are focussed on the use of precession electron diffraction for functional materials, mainly lithium based battery materials, but also a perovskite was included, since a large part of the audience worked on that subject.

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Electron crystallography for lithium based battery materials

  1. 1. University of Antwerp, Belgium Joke Hadermann Artem M. Abakumov Tyché Perkisas Zainab Hafideddine Stuart Turner Gustaaf Van TendelooMoscow State University, Russia Nellie R. Khasanova Evgeny V. Antipov
  2. 2. Transmission electron microscopy ...
  3. 3. Electron DiffractionTransmission electron microscopy
  4. 4. Precession Electron DiffractionTransmission electron microscopy
  5. 5. Precession Electron Diffraction Precession electron diffraction DOESallow structure solution and refinement from ED data
  6. 6. Precession electron diffractionVincent, R. & Midgley, P. A. Ultramicroscopy53 (1994) , 271-282.
  7. 7. Example: Li2CoPO4FThe problem: Structure cannot be solved from powder diffraction There are no single crystals.The solution: Achieve single crystal diffraction of the powder sample through precession electron diffraction.
  8. 8. First, electron diffractionpatterns are taken, using theprecession attachment.
  9. 9. All patterns can be indexed using the cellparameters and space groups known from XRD:a= 10.452(2) Å, b= 6.3911(8) Å, c=10.874(2) Å Pnma
  10. 10. The intensities of the observed peaks are extracted Geometric corrections applied Merged into one list We now have intensities of 237 symmetry unique reflections
  11. 11. Li2CoPO4Fa= 10.452(2) Å, Intensities of 237b= 6.3911(8) Å, & symmetry unique c=10.874(2) Å reflections Pnma INTO Direct Methods
  12. 12. Result: R=31% Co and P ≈ Li2FePO4F but Li, O, F mixed up F: tetrahedra around P O: complete octahedra around CoRemaining positions (purple): Li or ghosts? Difference Fourier maps
  13. 13. Straight from direct methods:too many Li(?) peaks Difference Fourier allows to eliminate the grey ones Structure is solved !
  14. 14. Can be refined...
  15. 15. Separate list of intensities per zone intoJana2006 using separate scale factors & Use PO4 rigid units: 18 variables reduced to 6 R=24% (reasonable for precession electron diffraction data)
  16. 16. Solved Refined
  17. 17. Li2CoPO4F was successfully solved andrefined from precession electron diffraction PED can be successfully applied for the crystallographic characterization of Li-based battery materials
  18. 18. A perovskite based example: Pb13Mn9O25 Starting point:a powder sample with nominal composition Pb2Mn2O5
  19. 19. Electron diffraction reveals three phases... Pnma; a= 5.7 Å, b=3.8 Å, c= 22 Å 1 P4/m; 2 a=b=14.2Å= ap√13 c=3.9 Å=ap 3 In progress
  20. 20. 1 ED, HAADF-STEM, EDX Pb2Mn2O5PbMn cf. MS79 P02 MS88 P12
  21. 21. 2 No solution from conventional (S)TEM
  22. 22. Precession electron diffraction Tilt series around a* axis: [100], [102], [103], [104], [105] + [001]C( g , R ) g( 1 ( g / 2R ) 2 )1 / 2 100 unique reflections in P4/m
  23. 23. Problems expected for direct methods! Have to find positions for oxygen (Z=8) while main impact from Pb(Z=82)
  24. 24. PED-data,composition PbMnO2.5, cell pars+SG R=34%
  25. 25. There are orderedmanganese vacancies.
  26. 26. There are ordered manganese vacancies.But where isthe oxygen?
  27. 27. Global optimization in direct space (FOX)
  28. 28. Structure optimisationE = -11.1 eV E = -7.42 eV
  29. 29. Structure of Li2CoPO4Fsolved using PED. Presence of cubic phase in layered phase LiCoO2 nanoparticles sample detected by PED.Structure of Pb13Mn9O25solved using PED.
  30. 30. For a more detailed treatment:“Solving the Structure of Li Ion Battery Materials with PrecessionElectron Diffraction: Application to Li2CoPO4F”Chem. Mater., 2011, 23 (15), pp 3540–3545http://pubs.acs.org/doi/abs/10.1021/cm201257b“Direct space structure solution from precession electron diffraction data:Resolving heavy and light scatterers in Pb13Mn9O25 ”Ultramicroscopy, 2010, 110, pp 881-890Ultramicroscopy 110 (2010) 881–890“New perovskite based manganite Pb2Mn2O5”Journal of Solid State Chemistry, 2010, 183 (9), pp 2190-2195Journal of Solid State Chemistry, Volume 183, Issue 9, p. 2190-2195 www.slideshare.net/johader

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