Effect of 1-allyl-1-methylpyrrolidinium chloride addition to ethylmagnesium bromide electrolyte on a rechargeable magnesium battery

•AMPyrCl is evaluated as an additive for a rechargeable Mg battery electrolyte.•AMPyrCl significantly enhances the anodic stability of EtMgBr by about 1 V.•AMPyrCl improves the coulombic efficiency and kinetics of Mg deposition and stripping.•AMPyrCl works well in a prototype cell consisting of a Mo6S8 cathode and Mg anode.

The ionic liquid 1-allyl-1-methylpyrrolidinium chloride was investigated as an additive to an ethylmagnesium bromide Grignard solution, for use as an advanced electrolyte in rechargeable Mg batteries. Electrochemical studies showed that the addition of the ionic liquid significantly enhanced the anodic limit of the Grignard solution by about 1 V and improved the coulombic efficiency and the kinetics of Mg deposition-stripping reactions on the negative electrode. We have also demonstrated that the Grignard solution containing the ionic liquid works well as an electrolyte in a prototype cell consisting of a Mo6S8 Chevrel phase cathode and a Mg metal anode, where the original Grignard electrolyte does not function properly.