Mixed ionic liquids as electrolyte for reversible deposition and dissolution of magnesium

In this paper we reported for the first time mixing two ionic liquids of 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) and N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide (PP13-TFSI) in the presence of 0.3 M Mg(CF3SO3)2 for use as electrolyte of reversible magnesium deposition and dissolution. Three kinds of mixture with volume ratios of 2:1, 3:1 and 4:1 for BMIMBF4 and PP13-TFSI were chosen and the magnesium deposition–dissolution process was investigated via coin cells. The mixed solution provided lower initial deposition–dissolution overpotential than every single ionic liquid system and the overpotential decreased with increasing the content of BMIMBF4. The mixture with 4:1 exhibited extreme low initial overpotential and the reversible process can be maintained over 200 cycles.