Electrochemical cycling of Mg in Mg[TFSI]2/tetraglyme electrolytes

The electrochemical reversibility of magnesium was observed in an electrolyte consisting of 0.5 M Mg[TFSI](2) in tetraglyme in the presence of a small amount of Mg[BH4](2). The cyclic efficiency of the cathodic/anodic process was found to increase initially with [BH4](-) then plateau at about 75% beyond 6 mM in these experiments. This concentration is in the region-of that indicated by Karl Fischer analysis of the electrolyte as required of [BE4] as a dehydrating agent. Cyclic voltammetry showed the reduction onset potential at approximately - 0.35 V vs. Mg and subsequent oxidation around 0 V vs. Mg. Stable cyclic efficiency of approximately 75% over 500 cycles is demonstrated on a platinum substrate. Mg cycling on magnesium, copper and aluminium substrates all show stable cycling over 500 cycles with cyclic efficiency >73%. (C) 2017 Elsevier B.V. All rights reserved.