Development of potassium ferrate(VI) cathode material stabilized with yttria doped zirconia coating for alkaline super-iron battery

摘要

To improve the stability of potassium ferrate(VI) (K_2FeO_4) cathode and its properties of charge transfer in alkaline battery system, K_2FeO_4 cathodes are coated by yttria (Y_2O_3) doped zirconia (ZrO_2) composites, denoted as Y_2O_3-ZrO_2 composite coatings. These composite coatings are derived from the conversion of yttrium nitrate (Y(NO_3)_3·6H_2O) and Zirconium oxychloride (ZrOCl_2·6H_2O) in ether medium. Examinations by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR) show that K_2FeO_4 cathodes are coated by Y_2O_3-ZrO_2 overlayer. Alternatively, results of discharge properties and electrochemical impedance spectroscopes (EIS) indicate that when the molar ratio between Y_2O_3 and ZrO_2 is 0.09, denoted as Y_2O_3 (9 mol%)-ZrO_2, the stability and charge transfer of Y_2O_3 (9 mol%)-ZrO_2 coated K_2FeO_4 cathodes are improved greatly compared to that of uncoated or ZrO_2 coated K_2FeO_4 cathodes. Therefore, Y_2O_3-ZrO_2 composite coatings are a potential choice to improve the stability and charge transfer of K_2FeO_4 cathodes in alkaline electrolyte.