Understanding Divalent Cation Intercalation in Manganese Oxides

The desire to improve the energy density of lithium ion batteries requires the discovery of different battery chemistries. One such class of batteries could use magnesium, calcium, or zinc metal counter electrodes paired with a transition metal oxide working electrode to achieve higher energy densities than lithium ion ones. However, divalent cations of these metals have sluggish kinetics of mobility in solids. Manganese oxides with the spinel and post-spinel crystal structures are predicted to have low energy barriers of divalent cation mobility. Additionally, theorists predict that shortened pathways will improve ion transport in crystalline solids. So, in addition to structural effects, nanoscale electrode materials are predicted to overcome these barriers as well. This work describes the synthesis of nanoscale spinel and microscale post-spinel manganese oxides, using colloidal and high-pressure methods, respectively. These materials will have their electrochemical performance assessed in nonaqueous electrolyte in order to determine their potential for use in magnesium batteries. Lastly, the electrochemical properties of micrometric spinel manganese oxide under reductive conditions in aqueous calcium and zinc electrolytes were studied and reported.