Preliminary investigation on the physicochemical properties of calcium ferrate(VI)

Calcium ferrate(VI) powders were synthesized from potassium ferrate(VI), and characterized by titration analysis, elemental analyzer, SEM, XRD, IR, TG and DSC. The results showed that the synthesized sample mainly consists of calcium ferrate(VI), and calcium ferrate(VI) may exist as CaFeO4 · 2H2O with a highest obtained purity of 74.9%. The relatively higher Fe(III) impurity and crystalloid water might be responsible for the poor stability of the calcium ferrate(VI) sample. The results of galvanostatic discharge experiments indicated that the calcium ferrate (VI) sample displays better intrinsic rate discharge capability and larger discharge capacity at lower temperatures (⩽15 °C).