57Fe Mössbauer study of the electrochemical reaction of lithium with triclinic iron vanadate

The electrochemical reaction of lithium with triclinic FeVO 4 (a = 6.714(1)A, b = 8.060(2) A, c = 9.352(2)A, a = 96.678(1)°, β = 106.641(1)°, and y = 101.523(1)°, P-1) has been investigated by means of 57 Fe Mossbauer spectroscopy in order to complement the previous X-ray diffraction and X-ray absorption near edge structure studies on the same system. A complex Fe III - Fe II - Fe 0 or Fe III Fe II , Fe 0 reduction process has been detected upon the first discharge of the battery down to 0.02 V, with in addition the iron reoxidation during the next charge step. A mechanism based on lithium adsorption is proposed in order to explain this unexpected behavior.