NOVELTY - The electrochemical device comprises an anode comprising magnesium, a cathode stable to a voltage of 3.2 V relative to a magnesium reference, and an electrolyte (5) that is obtained by admixture of a magnesium salt of a non-nucleophilic base comprising nitrogen and aluminum trichloride in an ether solvent. The non-nucleophilic base comprising nitrogen is a sterically hindered secondary amine or an aromatic heterocyclic nitrogen system. A molar ratio of the magnesium salt of the non-nucleophilic base comprising nitrogen admixed with the aluminum trichloride is 3/2 to 5/1.    USE - The magnesium sulfur electrochemical device such as lithium ion battery is useful as power sources for portable electronic devices and an electric vehicle.    ADVANTAGE - The magnesium sulfur electrochemical device can be easily, effectively and economically produced with high capacity, energy density, feasibility and safety, improved performance and light weight and without toxicity.    DETAILED DESCRIPTION - The electrochemical device comprises an anode comprising magnesium, a cathode stable to a voltage of 3.2 V relative to a magnesium reference, and an electrolyte (5) that is obtained by admixture of a magnesium salt of a non-nucleophilic base comprising nitrogen and aluminum trichloride in an ether solvent. The non-nucleophilic base comprising nitrogen is a sterically hindered secondary amine or an aromatic heterocyclic nitrogen system. A molar ratio of the magnesium salt of the non-nucleophilic base comprising nitrogen admixed with the aluminum trichloride is 3/2 to 5/1. The obtained electrolyte comprises an active magnesium salt, which is represented as (Mg2Cl3-6(C4H8O))+(AlCl3((CH3)3Si)2N)-. The electrolyte comprises the ether solvent (A) and the magnesium salt represented as (Mg2Cl3-6(A))+(AlCl3(B))-, where A is the ether solvent and B is an anion of the non-nucleophilic base. An INDEPENDENT CLAIM is included for a method for preparing an electrochemical device.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a magnesium sulfur electrochemical device.    Magnesium reference electrode (1)    Working electrode (2)    Polytetrafluoroethylene tube (3)    Magnesium counter electrode (4)    Electrolyte. (5)