THE SEARCH FORω-Li_xV_2O_5

摘要

Deep cycling of V_2O_5 films below 1.6 V vs. Li has been reported to produce ω-Li_xV_2O_5. a new cubic phase that can be reversibly cycled. This evidence comes mainly from x-ray diffraction (XRD) data. Other reports have attributed these observations to long range disorder in a linear combination of other crystalline phases. In this study we have employed films grown by pulsed laser deposition (PLD) and bulk powders to explore the nature of this phase. We have found that upon cycling below 1.6 V vs. Li we see clear XRD and Transmission Electron Microscopy (TEM) evidence for the formation of the ω-Li_xV_2O_5 phase. The phase cycles well between 4.0 and 1.5 V with a maximum capacity of 290 mAh/g and a loss of 15% over 50 cycles.