Designing High Voltage Electrolytes Based on Boron Clusters for Magnesium Batteries

Multivalent battery systems such as rechargeable magnesium (Mg) batteries have been proposed as candidates for post-lithium battery systems. In particular, Mg anode allows for a higher volumetric capacity (3833 mAh cm^-3 vs 2046 mAh cm^-3 for Li metal), while providing safer energy storage due to the formation of a protective film on the metal surface upon exposure to air or moisture. The feasibility of Mg battery technology was demonstrated in 2000, with the report of the one and only prototype to date.^[1] Despite the progress achieved to date, the main challenge in Mg battery development is the identification of a suitable electrolyte. The electrolyte should offer a large electrochemical window, and be compatible with battery components, such as Mg metal, high voltage cathodes and non-noble current collectors. While the vast majority of the available electrolytes contain halides in their structure, rendering them corrosive to non-noble metals,^[2] our group recently introduced magnesium borohydride as an alternative chloride-free electrolyte system.^[3] We are currently focusing on increasing the oxidative stability of borohydride anion by exploring larger boron hydride species such as polyhedral boron clusters.^[4] To that regard, we recently reported a magnesium carborane Grignard complex as the first proof-of-concept of a highly stable magnesium electrolyte of the B-H based family.^[5] This presentation will provide our latest results on the use of boron clusters in the design of magnesium electrolytes stable in contact with Mg metal, display an electrochemical window limited solely by solvent decomposition, and are compatible with non-noble metal electrodes.

References:

[1] D. Aurbach, Z. Lu, A. Schechter, Y. Gofer, H. Gizbar, R. Turgeman, Y. Cohen, M. Moshkovich, E. Levi, Nature 2000, 407, 724-727.

[2] J. Muldoon, C. B. Bucur, A. G. Oliver, J. Zajicek, G. D. Allred, W. C. Boggess, Energy Environ. Sci. 2013, 6, 482-487.

[3] R. Mohtadi, M. Matsui, T. S. Arthur, S.-J. Hwang, Angew. Chem. Int. Ed. 2012, 51, 9780 –9783.

[4] O. Tutusaus, R. Mohtadi, ChemElectrochem 2014, DOI:10.1002/celc.201402207

[5] T. J. Carter, R. Mohtadi, T. S. Arthur, F. Mizuno, R. Zhang, S. Shirai, J. W. Kampf, Angew. Chem. Int. Ed. 2014, 53, 3173 –3177.