Behavior of the monophosphate tungsten bronzes (m = 4 and 6) in electrochemical lithium insertion

摘要

Theelectrochemical lithium insertion process has been studied in the family of monophosphate tungsten bronzes (PO_2)_4(WO_3)_(2m); where m-4and 6.Structural changes in the pristine oxides were followed as lithium insertion proceeded. Through potentiostetic intenmttent technique, the different processes which take place in the cathode during the discharge of the cell were analysed. The nature of the bronzes Li_x(PO_2)_4(WO_3)_(2m) formed was determined by in situ X-ray diffraction experiments. These results have allowed establishment of a correlation with the reversible/irreversible processes detected during the electrochemical lithium insertion. Measurements of resistivity showed that upon lithium insertion, the metallic pristine oxides become insulating.