Abstract
In the paper, the isomorphous SO42- doped K(2)FeO(4), aimed at the remediation of the discharge and stability of the super-iron battery, was first synthesized for doping and reforming the K(2)FeO(4) crystalline structure via a facile co-precipitation and mechanochemistry. Afterwards, the compared cathodes were assembled by the undoped and doped K(2)FeO(4) for an evaluation of the discharge and stability in the AAA super-iron battery system. The results show that the small amounts of K(2)SO(4) were doped into the K(2)FeO(4) in the calculated form of K(2)Fe(1-x)S(x)O(4) by the isomorphous substitution. The doped K(2)FeO(4) cathodes/batteries exhibited an excellent discharge with a normal discharge profile. The cathodes doped by two techniques had significantly enhanced the discharge capacity of the super-iron battery with an increase of 10-30% compared to the undoped K(2)FeO(4). Moreover, the stability of the K(2)FeO(4) cathodes was obviously remediated by the isomorphous SO42- doping. The shelf time of the doped K(2)FeO(4) cathodes was prolonged by an increase of about 10% in comparison of the undoped K(2)FeO(4) cathode. The desirable enhancements could be attributed to doping and reforming the similar building block and isomorphous SO42- into the FeO42- tetrahedral and crystalline in the form of the isomorphous substitution and filling vacancies.