Reversibility of the lithium-vanadium bronze structure when cycled

Positive electrodes of secondary lithium batteries, based on Li1 + xV3O8 ob tained by the alcoxytechnology, are studied. As lithium intercalates, the i nitial crystalline bronze turns amorphous, remaining single-phase. An incre ase in the lithiation degree x leads to an almost linear decrease in parame ter a and increase in parameters b and c of the bronze crystal lattice; the changes are quite reversible when cycling. A noticeable degradation of ele ctric characteristics of electrodes is unrelated to irreversible structural changes and may be explained by the formation of passive films on the bron ze surface.