In Situ Raman Study of Phase Stability of α-Li 3 V 2 (PO 4 ) 3 upon Thermal and Laser Heating
2013; American Chemical Society; Volume: 117; Issue: 23 Linguagem: Inglês
10.1021/jp403282a
ISSN1932-7455
AutoresNellymar Membreño, Penghao Xiao, Kyusung Park, John B. Goodenough, Graeme Henkelman, Keith J. Stevenson,
Tópico(s)Luminescence Properties of Advanced Materials
ResumoMonoclinic α-Li3V2(PO4)3 has a complex 3-D metal phosphate framework that provides mobility for all three lithium ions, giving it the highest gravimetric capacity (197 mAh/g) of all the transition-metal phosphates. Along with its high gravimetric capacity, its thermal and electrochemical stability make it of great interest as a cathode material for lithium-ion energy storage devices. Raman spectroscopy has proven to be a unique analytical tool for studying electrode materials of lithium-ion batteries due to its ability to probe structural changes at the level of chemical bonds. In this work, the calculated Raman spectrum of α-Li3V2(PO4)3 provided by density functional theory is presented along with symmetry assignments for all of the calculated and observed modes through Raman microscopy. Furthermore, the phase stability of microcrystalline α-Li3V2(PO4)3 was studied as a function of irradiation power density. Follow-up thermal studies confirm that two structural phase transitions, β and γ, occur at elevated temperatures or high irradiation power density before degradation to α-LiVOPO4 under an oxygen-rich atmosphere. Calculated and experimentally determined Raman modes for α-Li3V2(PO4)3 are in good agreement. It is also noted that careful consideration of the irradiation power density employed must be taken into account to prevent misinterpretation of Raman spectral features.
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