LITHIUM INSERTION CHARACTERISTICS OF ALPHA-CU2V2O7

Lithium insertion characteristics of a complex oxide containing V(V), alpha-Cu2V2O7, were investigated. Lithium insertion was carried out chemically using an n-BuLi/hexane solution and also by the electrochemical GITT method comparatively. The valence states of copper or vanadium and the structural changes by lithium insertion were analyzed by ESR and XRD measurements, respectively. It was revealed that reduction processes occurred stepwisely with an increasing extent of lithium insertion, x in alpha-LixCu2V2O7. Up to x=1, a half of Cu(II) was reduced preferentially to Cu(I). Remaining Cu(II) and a half of V(V) were reduced at 1<x<3, and equimolar V(V) and V(IV) coexisted in addition to Cu(I) at x=3. At x>3, further, the reduction both of V(V) beyond V(IV)/V(V)=1 and of Cu(I) to Cu(0) occurred.