Preparation and stability study of potassium ferrate (VI) coated with phthalocyanine for alkaline super-iron battery

Abstract

The potassium ferrate (VI) coated with phthalocyanine (H2Pc) was successfully prepared via a facile co-precipitation process. Scanning electron microscopy and Fourier transform infrared spectrum revealed that K2FeO4 had been coated with H2Pc particles. When evaluated as cathodic material for alkaline super-ion battery, the effects of H2Pc coating on the electrochemical stability of K2FeO4 electrodes upon prolonged immersion time were investigated by galvanostatic discharge test, open-circuit potential measurements, and electrochemical impedance spectroscopy. The results show that the decomposition of K2FeO4 in electrolyte is obviously suppressed by H2Pc coating with a short immersion time, which could enhance the discharge capacity of electrodes. Furthermore, the open-circuit potential of the H2Pc-coated K2FeO4 electrode is higher than that of the bare K2FeO4 electrode, which indicates the improvement of anticorrosive ability. In addition, the ability of charge transfer between electrode and electrolyte is enhanced by H2Pc coating due to the inhibition on formation of Fe (III) layer, but the improved performance will decline upon prolonged immersion time.