Optimized preparation conditions of yttria doped zirconia coatings on potassium ferrate (Ⅵ) electrode for alkaline super-iron battery

摘要

To enhance the stability of potassium ferrate (Ⅵ) (K_2FeO_4) electrodes and their discharge capabilities in alkaline battery systems, yttria (Y_2O_3) doped zirconia (ZrO_2) (denoted as Y_2O_3-ZrO_2) coatings are utilized to protect the K_2FeO_4 electrode in alkaline electrolytes. The preparation conditions of Y_2O_3-ZrO_2 coatings on K_2FeO_4 electrodes are investigated in detail and the optimum preparation conditions are determined. Results of discharge tests with open module batteries show that the Y_2O_3-ZrO_2 coated K_2FeO_4 electrode (prepared under the optimum conditions) provides a superior discharge specific capacity than uncoated and ZrO_2 coated K_2FeO_4 electrodes. Alternatively, to further explore the practical application of K_2FeO_4 electrodes, super-iron coin cells are assembled using a Y_2O_3-ZrO_2 coated K_2FeO_4 electrode as the cathode and zinc foil as the anode. The discharge specific capacity and discharge specific energy of the coin cell with Y_2O_3-ZrO_2 coated K_2FeO_4 cathode are 169.8 mAhg~(-1) and 201.9 Wh kg~(-1) respectively, which are superior to the MnO_2 coin cell. Therefore, the results indicate that Y_2O_3-ZrO_2 coated K_2FeO_4 cathode is suitable for practical applications in alkaline battery systems. Consequently, the alkaline super-iron battery is expected to become a novel energy resource system that replaces present primary batteries in various electronic devices.