X-RAY-ABSORPTION FINE-STRUCTURE OF V2O5 AND LIXV2O5

Vanadium K-edge XAFS measurements of five compounds were carried out. The compounds studied were crystalline V2O5 and four types of LixV2O5 with different insertion levels x,which show different EMFs (2.0-3.4 V ). The EXAFS data analysis shows no remarkable difference in the V-O d istances in the five compounds, showing that the structure of the VO5 square pyramids changes only slightly as lithium atoms are intercalate d into the V2O5 In the XANES spectra, three peaks are observed for cry stalline V2O5 and LixV2O5 (3.4 V). When the EMF is decreased, the inte nsity difference between the first and second peaks disappears and the third peak shifts to lower energy. The XANES data were analysed using full multiple-scattering calculations. In the calculated spectra the intensity of the first peak increases as the V2O5 intercalates lithium atoms.