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
- 2. University of Antwerp, Belgium Joke Hadermann Artem M. Abakumov Tyché Perkisas Zainab Hafideddine Stuart Turner Gustaaf Van Tendeloo Moscow State University, Russia Nellie R. Khasanova Evgeny V. Antipov
- 4. Electron Diffraction Transmission electron microscopy
- 5. Precession Electron Diffraction Transmission electron microscopy
- 6. Precession Electron Diffraction Precession electron diffraction DOES allow structure solution and refinement from ED data
- 7. Precession electron diffraction Vincent, R. & Midgley, P. A. Ultramicroscopy 53 (1994) , 271-282.
- 8. Example: Li2CoPO4F The 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.
- 9. First, electron diffraction patterns are taken, using the precession attachment.
- 10. All patterns can be indexed using the cell parameters and space groups known from XRD: a= 10.452(2) Å, b= 6.3911(8) Å, c=10.874(2) Å Pnma
- 11. The intensities of the observed peaks are extracted Geometric corrections applied Merged into one list We now have intensities of 237 symmetry unique reflections
- 12. Li2CoPO4F a= 10.452(2) Å, Intensities of 237 b= 6.3911(8) Å, & symmetry unique c=10.874(2) Å reflections Pnma INTO Direct Methods
- 13. Result: R=31% Co and P ≈ Li2FePO4F but Li, O, F mixed up F: tetrahedra around P O: complete octahedra around Co Remaining positions (purple): Li or ghosts? Difference Fourier maps
- 15. Straight from direct methods: too many Li(?) peaks Difference Fourier allows to eliminate the grey ones Structure is solved !
- 17. Separate list of intensities per zone into Jana2006 using separate scale factors & Use PO4 rigid units: 18 variables reduced to 6 R=24% (reasonable for precession electron diffraction data)
- 18. Solved Refined
- 19. Li2CoPO4F was successfully solved and refined from precession electron diffraction PED can be successfully applied for the crystallographic characterization of Li-based battery materials
- 21. A perovskite based example: Pb13Mn9O25 Starting point: a powder sample with nominal composition Pb2Mn2O5
- 22. 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
- 23. 1 ED, HAADF-STEM, EDX Pb2Mn2O5 Pb Mn cf. MS79 P02 MS88 P12
- 24. 2 No solution from conventional (S)TEM
- 25. 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
- 26. Problems expected for direct methods! Have to find positions for oxygen (Z=8) while main impact from Pb(Z=82)
- 27. PED-data, composition PbMnO2.5, cell pars+SG R=34%
- 28. There are ordered manganese vacancies.
- 29. There are ordered manganese vacancies. But where is the oxygen?
- 30. Global optimization in direct space (FOX)
- 31. Structure optimisation E = -11.1 eV E = -7.42 eV
- 33. Structure of Li2CoPO4F solved using PED. Presence of cubic phase in layered phase LiCoO2 nanoparticles sample detected by PED. Structure of Pb13Mn9O25 solved using PED.
- 34. For a more detailed treatment: “Solving the Structure of Li Ion Battery Materials with Precession Electron Diffraction: Application to Li2CoPO4F” Chem. Mater., 2011, 23 (15), pp 3540–3545 http://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 881-890 Ultramicroscopy 110 (2010) 881–890 “New perovskite based manganite Pb2Mn2O5” Journal of Solid State Chemistry, 2010, 183 (9), pp 2190-2195 Journal of Solid State Chemistry, Volume 183, Issue 9, p. 2190-2195 www.slideshare.net/johader