Reversible Behavior of K_2Fe(VI)O_4 in Aqueous Media

摘要

The chemistry of the Fe(VI) compound, K_2FeO_4, was investigated in aqueous potassium hydroxide electrolyte for its potential use in secondary storage Systems. High charge storage K_2FeO_4 material was synthesized using alkaline hypochlorite oxidation of ferric nitrate and characterized by in Situ X-ray diffraction and Mossbauer spectroscopy. The discharge-charge profile of the cathode, measured vs. a zinc anode, was semiquantitatively correlated with changes in Fe~(6+)/Fe~(3+) ratio and the nature of structural transformation at each stage by in Situ Mossbauer and in Situ synchrotron X-ray diffraction spectroscopy. The data in conjunction with the charge-discharge profile clearly indicates the rechargeability of K_2FeO_4 with a charge efficiency of about 36 percent of the total current passed under the prevailing experimental conditions. These results are potentially important to the design of Fe~(6+) compound analogs for use in secondary energy storage systems.