Features of the electrochemical lithium insertion into monophosphate tungsten bronzes (PO2)(4)(WO3)(2m) (m=9 and 10)

摘要

Electrochemical lithium insertion into (PO2)(4)(WO3)(2m), where m = 9 and 10, has allowed the determination of several phases Li-x(PO2)(4)(WO3)(2m) between 3.4 and 0.01 V vs Li+/Li-0. After the first cycle the electrochemical system was unable to maintain the high specific capacity of the cells (similar to 540 Ah/kg) due to irreversible processes. Nevertheless at high voltage values, above 1.4V vs Li+/Li-0, the lithium insertion proceeded through a reversible mechanism. By means of X-ray diffraction experiments we have detected the nature of different phases Li-x(PO2)(4)(WO3)(2m) formed and we have established a correlation with the reversible/irreversible processes detected during the electrochemical insertion. (C) 2007 Elsevier Ltd. All rights reserved.