کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1331314 | 979002 | 2010 | 7 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: New ramsdellites LiTi2−yVyO4 (0≤y≤1): Synthesis, structure, magnetic properties and electrochemical performances as electrode materials for lithium batteries New ramsdellites LiTi2−yVyO4 (0≤y≤1): Synthesis, structure, magnetic properties and electrochemical performances as electrode materials for lithium batteries](/preview/png/1331314.png)
The new ramsdellite series LiTi2−yVyO4 (0≤y≤1) has been prepared by conventional solid state chemistry techniques and was characterized by X-ray powder diffraction and electron diffraction. To our knowledge, this is the first report on ramsdellites containing vanadium. The magnetic behaviour of these ramsdellites is strongly influenced by its vanadium content. In this sense, LiTi2O4 (y=0) exhibits metallic-like temperature independent paramagnetism, but d electrons tend to localize with increasing V content. LiTiVO4, though also paramagnetic, follows then the Curie–Weiss law. The crossover from delocalized to localized electrons is observed between compositions y=0.6 and 0.8. For y≥0.8 the magnetic results evidence an isovalent substitution mechanism of trivalent Ti by V. The electrochemical lithium intercalation and deintercalation chemistry of LiTi2−yVyO4 is grouped into two different operating voltage regions. Reversible lithium deintercalation of vanadium-substituted ramsdellite titanates LiTi2−yVyO4 in the high voltage range 2–3 V vs. Li occurs in two main steps, one at about 2 V and the other at about 3 V. The 3 V process capacity increases with the vanadium content, while the 2 V capacity decreases at the same time. The vanadium to titanium substitution rate in LiTi2O4 was found to be beneficial to the specific energy in as much as a 50% increase (1 V) of the working voltage is observed. On the other hand, reversible lithium intercalation in vanadium-substituted ramsdellite titanates LiTi2−yVyO4 in the low voltage range 1–2 V vs. Li occurs in one main single step, in which the capacity is not affected by the vanadium content, although vanadium-doping produces an improved capacity retention with an excellent cycling behaviour observed for y≤0.6.
Ti-based ramsdellite compounds can make up cathode and anode materials for lithium batteries by introducing vanadium. Lithium deinsertion experiments on LiTi2−yVyO4 materials develop a high operating voltage (3 V) useful as the cathode, while lithium insertion experiments yield a low operating voltage, 1.5 V, useful as the anode. Vanadium-rich compounds show specific theoretical capacity values in the high voltage range that are even comparable to those reported for LiFePO4 which is presently one of the preferred cathode materials for lithium batteries.Figure optionsDownload as PowerPoint slide
Journal: Journal of Solid State Chemistry - Volume 183, Issue 1, January 2010, Pages 20–26