Pyrazolyl magnesium halide/tetrahydrofuran solutions for rechargeable magnesium battery electrolytes

Abstract

Pyrazolyl magnesium halide/tetrahydrofuran (THF) solutions were obtained by the simple reaction of pyrazole compounds with Grignard reagents in THF. Their electrochemical performances as rechargeable magnesium battery electrolytes are reported. The pyrazolyl magnesium halide/THF solutions were characterized in term of anodic stability and reversibility of magnesium deposition-dissolution using cyclic voltammetry and galvanostatic charge-discharge techniques. The composition and morphology of the deposit were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). It is concluded that the substituents on the pyrazole compound and the molar ratio of the pyrazole to the Grignard both affect the electrochemical performance. An electrolyte consisting of 1 mol∙L-1 1-methylpyrazole-PhMgCl (1:1 molar ratio)/THF has an anodic oxidation decomposition potential of 2.4 V (vs Mg/Mg2+) on stainless steel (SS), a low potential for magnesium deposition-dissolution, and a high cycling reversibility, and can be prepared easily, making it a promising candidate for rechargeable battery electrolytes.