Magnesium Deintercalation From the Spinel‐Type MgMn(2‐y)Fe(y)O(4) (0.4≤y≤2.0) by Acid‐Treatment and Electrochemistry

Rechargeable magnesium batteries attract lots of attention because of their high safety and low cost compared to lithium batteries, and it is needed to develop more efficient electrode materials. Although MgMn(2)O(4) is a promising material for the positive electrode in Mg rechargeable batteries, it usually exhibits poor cyclability. To improve the electrochemical behavior, we have prepared nanoparticles of MgMn(2‐y)Fe(y)O(4). The XRD results have confirmed that when Mn(3+) (Jahn‐Teller ion) ions are replaced by Fe(3+) (non‐Jahn‐Teller ion), the resulting MgMn(2‐y)Fe(y)O(4) is a cubic phase. The structure and theoretical voltage are theoretically calculated by using the DFT method. The obtained samples have been chemically treated in acid solution for partial demagnesiation, and it is observed that the presence of iron inhibits the deinsertion of Mg through disproportionation and favors the exchange reaction. The electrochemical behavior in non‐aqueous magnesium cells has been explored.