In the last years, massive improvements have been achieved in the field of battery technology opening the door to more efficient electric vehicles and electric power storage. Nevertheless, further research is needed to overcome lithium drawbacks and enter in the such called “beyond Li-ion” technology [1]. In this perspective, magnesium secondary batteries are promising electrochemical storage devices due to their a) high volumetric capacity (3832 mAh·cm^-3), b) great abundance and homogeneous spread of Mg in the Earth’s crust, c) safety and environmentally friendliness, and d) low standard reduction potential (-2.36 V). The main roadblock to the enter of these devices in the global market is the development of a safe and efficient electrolyte. In the last 3 years it has been demonstrated that electrolytes obtained by dissolving a suitable magnesium salt (δ-MgCl₂) into ionic liquids (ILs) are able to efficiently deposit and strip magnesium with very low overpotentials and high current densities [2-4].

In the present work a new family of electrolytes is proposed, based on 1-Butyl-1-methylpyrrolidinium chloride and boron trichloride, doped with δ-MgCl₂. The thermal stability and transitions of the proposed materials is studied using HR-TGA and MDSC. The structure and interactions of the materials are investigated by vibrational spectroscopies (FT-IR and confocal micro-Raman). Finally, Broadband Electrical Spectroscopy is exploited to elucidate the electric response of materials and to detect the long-range charge migration mechanisms of the electrolytes.

References

[1] V. Di Noto, S. Lavina, G.A. Giffin, E. Negro, B. Scrosati, Electrochim. Acta, 57 (2011) 4-13.

[2] F. Bertasi, C. Hettige, F. Sepehr, X. Bogle, G. Pagot, K. Vezzù, E. Negro, S.J. Paddison, S.G. Greenbaum, M. Vittadello, V. Di Noto, ChemSusChem, 8 (2015) 3069-3076.

[3] F. Bertasi, F. Sepehr, G. Pagot, S.J. Paddison, V. Di Noto, Adv. Funct. Mat., 26 (2016) 4860-4865.

[4] G. Pagot, F. Bertasi, K. Vezzù, F. Sepehr, X. Luo, G. Nawn, E. Negro, S.J. Paddison, V. Di Noto, Electrochim. Acta, 246 (2017) 914-923.