Electronic structures of LiFePO4 and related materials - Wake Forest ...

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What can computer simulations do to advanceour understanding of LiFePO 4 materials?The role of computation in electrochemical research is not as prominent as it isin the semiconductor and catalysis fields. Our work was inspired by a talk givenby Professor Gerbrand Ceder of M. I. T. given at the Fourteenth AnnualWorkshop on Recent Developments in Electronic Structure Methods – ES2002 inwhich he summarized his pioneering work on the cathode materials LiCoO 2 ,LiNiO 2 , and LiMn 2 O 4 . (More recently, Ceder and his group have made majoradvances in the understanding of the LiFePO 4 family as well.)Outline of our work• Introduction to the general features of the electronic structures of theelectrochemically active forms of LiFePO 4 and FePO 4 .• Comparison of the electrochemically active form of FePO 4 with 3 othermeta-stable crystalline structures.• Beginning work on Li-ion diffusion mechanisms in Li 3 PO 4 .8
Calculational methodsMethodPAWpwpaw - pwpaw.wfu.edusocorro - dft.sandia.gov/socorroabinit - www.abinit.orgLAPWwien2k - www.wien2k.atPWscfpwscf - www.pwscf.orgCommentsWorks well for moderately large unit cells,but variable unit cell optimization not yet implementedin pwpaw and socorro. Need toconstruct and test PAW basis and projectorfunctions.Works well for smaller unit cells; variable unitcell optimization not implemented. Need tochoose non-overlapping muffin tin radii andavoid “ghost” solutions.Works well for large unit cells and includesvariable unit cell optimization. Need to constructand test soft pseudopotential functions.9
Page 1 and 2: Electronic structures ofLiFePO 4 an
Page 3 and 4: Diagram of discharge operation for
Page 5 and 6: J. Electrochem. Soc. 144 1188, (199
Page 7: Commercial use of LiFePO 4 ???(pure
Page 11 and 12: Details on constructing the PAW bas
Page 13 and 14: Test results for simple oxides∆E
Page 15 and 16: FePO 4 and LiFePO 4in olivine (Pnma
Page 17 and 18: Partial densities for majority spin
Page 19 and 20: Summary of results for FePO 4 and L
Page 21 and 22: Computational challenge1. Can we re
Page 23 and 24: Crystal structures - continued“Cr
Page 25 and 26: Internal Energy Differences(in unit
Page 27 and 28: LSDA band gaps and widths for FePO
Page 29 and 30: Li-ion diffusion mechanisms in elec
Page 31 and 32: Li + diffusion by possible vacancy
Page 33 and 34: Summary• With careful attention t

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