Abstract
Electrochemical properties of iron carbide (Fe3C) for an anode of alkaline battery and the effects of the electrode voidage on the performance of the battery were investigated. Cyclic voltammetry and charge-discharge measurements showed that the oxidization process of Fe3C is different from that of pure iron, but it is irreversible. In charge-discharge cycles, discharge characteristics of Fe3C became like those of pure iron, and the particles were pulverized to be smaller than 100 nm in diameter. By comparing of the discharge curves of electrodes with various value of voidage, it was found that the lower the voidage of the electrode was, the more specific capacity increased, up to as much as 450 mAh/g. In addition a maximum of the discharge potential appears at the voidage of 60%. Results of AC-impedance spectroscopy (ACIS) showed that the effective value of reaction surface area increased with the voidage to reach a maximum at the voidage of 60%. The opposite effects of voidage on the contact resistance between electrode particles and the diffusion resistance of electrolyte in the three-dimensional electrode were balanced to exhibit best electrode performance at the voidage of 60%.
