Organo Metallic Free Electrolytes for Magnesium Rechargeable Batteries

Developing an organo-metallic free electrolytic solution is crucial step towards a practical magnesium battery system. Implementing Grignard reagents in a commercial battery would pose a great impediment owing to the material’s high cost, its hazardous nature, and high susceptibility towards oxidation. The Magnesium Aluminum Chloro Complex (MACC) solutions, developed at the Bar Ilan University in conjunction with its allies at Pellion, Cambridge, MA, consist of solely inorganic salts; MACC is the reaction products of the acid base reaction between MgCl₂ and AlCl₃ in the right proportion in THF. MACC solutions are endowed with high Mg deposition/stripping cycling efficiency, upwards of 99%, low over-potential for magnesium deposition and a wide electrochemical window of 3.1V. Reversible intercalation/de-intercalation of Mg ions into Chevrel-phase Mo₆S₈, from a MACC solution has also been demonstrated. Normally, freshly synthesized MACC solution exhibits very poor magnesium deposition/dissolution reversibility. However, it was discovered serendipitously that by an electrochemical process, coined “conditioning”, it is possible to significantly enhance the electrochemical characteristics of such electrolyte solutions. The electrochemical “conditioning” consist of slowly electrochemically cycling the solutions in a sealed cell, using Pt as WE and Mg foil as CE in the potential range of -1.2V and 2.8V. This study is an important step forward, eliminating the need for Grignard/organo-metallic based electrolytes with their intrinsic disadvantages, and towards a more “simple salt” based system.