Electrochemical characteristics of iron carbide as an active material in alkaline batteries

Electrochemical properties of iron carbide (Fe3C) for use as an alkaline battery anode were investigated during charge–discharge cycles. Results of electrochemical measurements and Mössbauer spectroscopy suggested that Fe3C is oxidized irreversibly to Fe3O4 during discharge processes and that the produced Fe3O4 is subsequently changed to Fe(OH)2 and Fe during the charging process, raising the discharge/charge capacity in further galvanostatic cycles. In addition, the electrode particles were observed to be less than 100 nm in diameter and to be highly dispersed on the surface of carbon black. These phenomena seems to be caused by dissolution and deposition of Fe(OH)2 and Fe via intermediate iron species, leading to exposure of a fresh Fe3C surface to the electrolyte after the second discharge.