Synthesis, spectral character, electrochemical performance and in situ structure studies of Li1+xV3O8 cathode material prepared by tartaric acid assisted sol-gel process

Lithium-ion battery cathode material Li1+xV3O8 was synthesized by a tartaric acid assisted sol-gel method and thermally treated at 350 degrees C, 450 degrees C and 550 degrees C for 3 h for the formation of Li1+xV3O8 phase. The synthesized samples were fully characterized by FTIR, TG/DTA, XRD and charge-discharge tests. Li1+xV3O8 material synthesized by tartaric acid assisted route, followed by heat treatment at 450 degrees C for 3 h shows best electro-chemical performance. It shows a high initial capacity of 249 mAh g(-1) and still reserves a discharge capacity of 260 mAh g(-1) after 50 cycles. Moreover, for all tartaric assisted products, no capacity decadence is observed in 50 cycles. The in situ X-ray measurements reveal a two-phase transition mechanism in the lithium intercalation/deintercalation process. During lithium extraction, the structure of the delithiated compound changes from Li4V3O8 (x > 3.1) to the original LiV3O8 phase (x < 1.4) via the coexistence state of these two phases (1.4 < x < 3.2). An obvious contraction, especially at Li(3)-Li(4) transition, along a axis and a slight expansion along b axis are also observed. (C) 2012 Elsevier Ltd. All rights reserved.