In Situ Raman Study of Phase Stability of 伪-Li3V2(PO4)3 upon Thermal and Laser Heating

详细信息    查看全文

• 作者：Nellymar Membre帽o ; Penghao Xiao ; Kyu-Sung Park ; John B. Goodenough ; Graeme Henkelman ; Keith J. Stevenson
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：June 13, 2013
• 年：2013
• 卷：117
• 期：23
• 页码：11994-12002
• 全文大小：511K
• 年卷期：v.117,no.23(June 13, 2013)
• ISSN：1932-7455

文摘

Monoclinic 伪-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 伪-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 伪-Li₃V₂(PO₄)₃ was studied as a function of irradiation power density. Follow-up thermal studies confirm that two structural phase transitions, 尾 and 纬, occur at elevated temperatures or high irradiation power density before degradation to 伪-LiVOPO₄ under an oxygen-rich atmosphere. Calculated and experimentally determined Raman modes for 伪-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.