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Li−Fe−P−O2 Phase Diagram from First Principles Calculations
- Source :
- Chemistry of Materials. 20:1798-1807
- Publication Year :
- 2008
- Publisher :
- American Chemical Society (ACS), 2008.
-
Abstract
- We present an efficient way to calculate the phase diagram of the quaternary Li−Fe−P−O2 system using ab initio methods. The ground-state energies of all known compounds in the Li−Fe−P−O2 system were calculated using the generalized gradient approximation (GGA) approximation to density functional theory (DFT) and the DFT+U extension to it. Considering only the entropy of gaseous phases, the phase diagram was constructed as a function of oxidation conditions, with the oxygen chemical potential, μO2, capturing both temperature and oxygen partial pressure dependence. A modified Ellingham diagram was also developed by incorporating the experimental entropy data of gaseous phases. The phase diagram shows LiFePO4 to be stable over a wide range of oxidation environments, being the first Fe2+-containing phase to appear upon reduction at μO2 = −11.52 eV and the last of the Fe-containing phosphates to be reduced at μO2 = −16.74 eV. Lower μO2 represents more reducing conditions, which generally correspond to higher t...
Details
- ISSN :
- 15205002 and 08974756
- Volume :
- 20
- Database :
- OpenAIRE
- Journal :
- Chemistry of Materials
- Accession number :
- edsair.doi...........d83f14452c9dda04a0d3421cdc73e154