(103c) Nonaqeous Electrolytes for Magnesium-Oxygen Batteries | AIChE

(103c) Nonaqeous Electrolytes for Magnesium-Oxygen Batteries


Vardar, G. - Presenter, University of Michigan
Monroe, C. W., University of Michigan
Sleightholme, A. E. S., University of Michigan
Saraidaridis, J. D., University of Michigan
Siegel, D. J., University of Michigan

Because of their high theoretical energy densities, metal-O2 batteries
have long been considered as an improvement upon current battery technologies. Mg-O2
batteries have one of the highest predicted volumetric energy densities [1]. However,
rechargeable Mg-O2 batteries are not possible to realize with
aqueous electrolytes due to non-conducting reaction products that form on the Mg anode.
Non-aqueous Mg-conducting electrolytes have been studied in the context of
Mg-ion and Mg-sulfur batteries [2]. Our goal is to develop a non-aqeuous
electrolyte that is compatible with an O2 cathode and stable for the
MgO (2.95V vs. Mg/Mg++) and MgO2 (2.91V vs. Mg/Mg++)
formation reactions.

this presentation, we will discuss our latest progress in electrolytes for rechargeable
Mg-O2 batteries. Figure 1 shows a cyclic voltammogram
measured in magnesium borohydride (Mg(BH4)2)
in dimethoxyethane (DME). The oxidative stability of Mg(BH4)2 in DME was found to be below 2V on a Pt
working electrode. Interestingly, ionic liquids are known to have wide
electrochemical windows. The oxidative stability of 1-Butyl-3-methylimidazolium
bistrifluoromethylsulfonylimide (BmimTFSI) in DME was
measured to be over 3V vs. Mg/Mg++ (Figure 2). However, addition of
BmimTFSI to the Mg(BH4)/DME solution reduced the reductive stability
window considerably and Mg deposition/dissolution was not observed. Mg
deposition and dissolution experiments are underway for non-aqueous systems with
ionic liquids as the supporting electrolyte.

C.-X. Zu and H. Li, "Thermodynamic analysis on energy densities of
batteries," Energy &
Environmental Science, 4, 2614,

J. Muldoon et al., "Electrolyte roadblocks to a magnesium rechargeable
battery," Energy &
Environmental Science, 5,
5941 (2012).