Reversibility of electrochemical magnesium deposition from tetrahydrofuran solutions containing pyrrolidinyl magnesium halide

► We reported firstly C4H8NMgX/THF for reversible magnesium deposition and dissolution. ► These solutions have high conductivity, anodic stability and reversibility. ► The reversibility of magnesium depended on the morphology of magnesium deposit. ► The morphology of magnesium deposit was controlled by the metal substrates. In this paper we reported for the first time the electrochemical behavior of pyrrolidinyl magnesium halide (C4H8NMgX, X=Br and Cl) dissolved in tetrahydrofuran (THF) with regard to potential application as electrolytes for rechargeable magnesium batteries. C4H8NMgX/THF solutions were characterized in term of conductivity, anodic stability, and reversibility of magnesium deposition and dissolution. Furthermore, the effect of metal substrates on magnesium deposition process was studied. Simple preparation, high cycling reversibility and moderate anodic stability of C4H8NMgBr/THF solution indicate the feasible application as the electrolyte for rechargeable magnesium batteries.