Deciphering the Structure of the Magnesium Aluminum Chloride Electrolyte in Bulk and Near the Anode Electrode

Electrical energy storage is a key technology for a clean energy economy, but currently requires significant improvement in energy density beyond the capabilities of traditional Li-ion batteries. Mg-ion batteries are an exciting alternative in terms of the amount of energy that can be delivered, safety, manufacturing and disposal costs, with limited environmental impact. The electrochemical functions of the Mg-ion battery rely on the choice of the electrolyte, which is limited by the distinct chemistry of Mg. To date, very few electrolytes can reversibly plate and strip Mg [1,2]. The magnesium aluminum chloride complex (MACC) electrolyte can reversibly plate and strip Mg with significantly higher voltage (3.1 V) as compared to other electrolytes, but there is a pressing need to address critical questions about the structural evolution of this electrolyte during electrochemical cycling [3]. While it is well established that Mg can be deposited reversibly from complex ethereal solutions of Mg-Al chloride complex reagents, the stripping/deposition mechanism at the anode is still debated [2,3]. In this poster we present a detailed atomistic DFT study of the electrolyte in bulk and when in contact with Mg-anode surfaces. These models are essential to clarify the structure of the electrolyte under various environmental conditions as well as to provide insight on the electron-transfer mechanism occurring at the electrode/solvent interface [4,5]. [1] D. Aurbach, Z. Lu, A. Schechter, Y. Gofer, H. Gizbar, R. Turgeman, Y. Cohen, M. Moshkovich, and E. Levi, Nature 407 , 724–727 (2002). [2] N. Pour, Y. Gofer, D. T Major, and D. Aurbach, J. Am. Chem. Soc. 133 , 6270–6278 (2011). [3] R. E. Doe, R. Han, J. Hwang, A. J. Gmitter, I. Shterenberg, H. D. Yoo, N. Pour, and D. Aurbach, Chem. Commun. 50 , 243–245 (2014). [4] P. Canepa, G. S. Gautam, R. Malik, S. Jayraman, Z. Rong, K. R. Zavadil, K. Persson, G. Ceder, Chem. Mater. 27 (9), 3317–3325 (2015). [5] P. Canepa, S. Jayaram, L. Cheng, N. N. Rajput, W. D. Richards, S. G. Gautam, L. A. Curtiss, K. A. Persson and G. Ceder, Energy Environ. Sci. 8 , 3718–3730 (2015).