Temperature Dependence of Aliovalent-vanadium Doping in LiFePO4 Cathodes

Journal Article · Tue Jan 01 00:00:00 EST 2013 · Chemistry of Materials

DOI:https://doi.org/10.1021/cm303932m· OSTI ID:1092207

Harrison, Katharine L ^[1]; Bridges, Craig A ^[2]; Paranthaman, Mariappan Parans ^[2]; Idrobo Tapia, Juan C ^[2]; Manthiram, Arumugam ^[1]; Goodenough, J. B. ^[1]; Segre, C ^[3]; Katsoudas, John ^[3]; Maroni, V. A. ^[4]

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1. University of Texas at Austin
2. ORNL
3. Illinois Institute of Technology
4. Argonne National Laboratory (ANL)

Vanadium-doped olivine LiFePO4 cathode materials have been synthesized by a novel low-temperature microwave-assisted solvothermal (MW-ST) method at 300 oC. Based on chemical and powder neutron/X-ray diffraction analysis, the compositions of the synthesized materials were found to be LiFe1-3x/2Vx x/2PO4 (0 x 0.2) with the presence of a small number of lithium vacancies charge-compensated by V4+, not Fe3+, leading to an average oxidation state of ~ 3.2+ for vanadium. Heating the pristine 15 % V-doped sample in inert or reducing atmospheres led to a loss of vanadium from the olivine lattice with the concomitant formation of a Li3V2(PO4)3 impurity phase; after phase segregation, a partially V-doped olivine phase remained. For comparison, V-doped samples were also synthesized by conventional ball milling and heating, but only ~ 10 % V could be accommodated in the olivine lattice in agreement with previous studies. The higher degree of doping realized with the MW-ST samples demonstrates the temperature dependence of the aliovalent-vanadium doping in LiFePO4.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). High Temperature Materials Lab. (HTML); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Shared Research Equipment Collaborative Research Center
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1092207
• Journal Information: Chemistry of Materials, Vol. 25, Issue 5; ISSN 0897--4756
• Country of Publication: United States
• Language: English