Synthesis of calcium and magnesium periodates for the development of high oxidation state battery cathodes

We present the synthesis of calcium and magnesium periodates using NaIO₄ and corresponding CaCl₂ and MgCl₂ respectively via precipitation reactions. The elemental analysis shows a 1:1 atomic ratio between the metal and iodine. It is also found that during the synthesis, metaperiodate anions are converted to orthoperiodate anions. The synthesized samples are hydrated and have crystalline structures; yet upon heating, the structures of the samples turn amorphous. Periodate-zinc batteries are fabricated which utilize the oxidizing properties of the periodates. The Ca periodate, with an estimated formula of CaOH(H₄IO₆)⸱5H₂O, exhibits a specific capacity of 460 mAh g⁻¹ and a cell voltage of 1.4 V when combines with a zinc anode. Mg periodate is less suitable for electrode formulation due to its higher aqueous solubility and lower stability.