delta AgyV2O5 has been characterized as the active material for secondary lithium batteries by using electrochemical measurements and X-ray diffraction. Lithium insertion proceeds in three steps that include deposition of metallic silver and phase transformation to epsilon LixV2O5. Metallic silver does not return to the original matrix during recharging. During the charge process, additional lithium is accommodated in the first and second steps. (C) 1998 Elsevier Science S.A.