Abstract
Nanocrystalline LiFePO4 powders synthesized by a microwave-assisted solvothermal (MW-ST) process have been structurally characterized with a combination of high resolution powder neutron diffraction, synchrotron X-ray diffraction, and aberration-corrected HAADF STEM imaging. A significant level of defects has been found in the samples prepared at 255 and 275 °C. These temperatures are significantly higher than what has previously been suggested to be the maximum temperature for defect formation in LiFePO4, so the presence of defects is likely related to the rapid MW-ST synthesis involving a short reaction time (̃5 min). A defect model has been tentatively proposed, though it has been shown that powder diffraction data alone cannot conclusively determine the precise defect distribution in LiFePO4 samples. The model is consistent with other literature reports on nanopowders synthesized at low temperatures, in which the unit cell volume is significantly reduced relative to defect-free, micron-sized LiFePO4 powders.
Original language | English |
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Pages (from-to) | 197-204 |
Number of pages | 8 |
Journal | Journal of Solid State Chemistry |
Volume | 205 |
DOIs | |
State | Published - 2013 |
Funding
This work was supported by the U.S. Department of Energy, Basic Energy Sciences, Materials Sciences and Engineering Division, at the University of Texas at Austin (under award number DE-SC0005397) and at Oak Ridge National Laboratory (ORNL). We acknowledge Ashfia Huq and Jason Hodges for assistance with collection of powder neutron diffraction data at the Spallation Neutron Source (SNS). Research at ORNL's SNS, Center of Nanophase Materials Sciences (CNMS) and Shared Research Equipment (ShaRE) User Facility Programs were sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. One of the authors (KH) thanks the National Science Foundation for the award of a Graduate Research Fellowship. Appendix A
Keywords
- Antisite disorder
- Lithium-ion batteries
- Neutron diffraction