This project will move our research efforts in a new direction, towards rational design and discovery of completely new cathode materials compatible with fast magnesium ion conductors created by this project. Novel solid-state ion conductors may enable the use of other types of cathode materials as used to day. Initially, magnesium foil may be used directly as anode, which facilitate development of better, safer and cheaper solid-state batteries with much higher energy density as compared to state-of-the-art lithium batteries. Advanced materials characterization will provide deeper understanding of solid electrolyte interface formation and how to avoid ion blocking layers to form. Deeper knowledge about electrolyte-electrode reactivity, electrochemical stability and interface formation will also be extracted. This is a direct link to rational design of novel functional battery materials. This project potentially has a significant societal impact for storage of renewable energy.
The chemistry of metal borohydrides (Mx(BH4)x) and their derivatives has expanded signficantly during the past decade involving new compositions, structures, and the diversity of associated properties. Here we provide an overview of interesting results mainly from the past few years, discussed relative to previously published results. A range of new synthesis strategies has been developed to obtain pure samples, which has allowed very detailed structural, physical, and chemical investigations. Metal borohydrides appear to be the most promising class of materials to achieve high cationic conductivity of divalent metals, and particularly derivatives of metal borohydrides with neutral molecules show promise as future electrolytes for new types of solid-state batteries. Magnesium borohydride itself is an insulating material both ionic and electronic due to its rigid structure and the lack of a redix active species, however when coordinated to neutral molecule, ionic conductivity increases by as much as a factor 109 at room temperature. Due to this, the group has worked towards rational design, by testing different ligands.