TECHNOLOGY FOCUS - ELECTRONICS - Preferred Components: The electrolyte comprises 0.1-10 M (I) and 0.001-10 M Lewis acid. The battery further comprises a separator (4) disposed between cathode and the anode. The anode comprises at least one of a magnesium metal, a magnesium-based alloy or a magnesium intercalating compound. The cathode is at least one of magnesium composite metal oxide and at least one of oxide, sulfide, or halide of at least one metal comprising scandium, ruthenium, titanium, vanadium, molybdenum, chromium, manganese, iron, cobalt, nickel, copper or zinc.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: A molar ratio of (I) to Lewis acid is 1:1-1:0.001. The Lewis acid comprises at least one of aluminum chloride or boron trifluoride (both preferred), trimethylaluminum, aluminum hydride, aluminum alkoxide of formula (Al(OR)3, aluminum3+, boron trichloride, boron alkoxide of formula (B(OR)3), carbonyl compound (R-C=O+), isocyanide+, carbon dioxide, alkyl silane compound (R3Si+), silicon4+, phosphorus oxide of formula (RPO2+) or (ROPO2+), arsenic3+, sulfur oxide compound of formula (RSO2+) or (ROSO2+), sulfurtrioxide, selenium3+, chromium+, iodine7+, iodine5+, lithium+, sodium+, potassium+, dimethyl beryllium, beryllium2+, calcium2+, strontium2+, trimethyl gallium, gallium3+, trimethyl gallium indium, indium3+, tin compound (SnR3+), methyl tin compound (Sn(CH3)2), tin2+, scandium3+, lanthanum3+, titanium alkoxide of formula (Ti(OR)4), titanium4+, zirconium4+, vanadium oxide (VO2+), chromium3+, iron3+, cobalt3+, iridium3+, thorium4+, uranium oxide (UO2)2+, plutonium4+ or terbium3+ ion.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The organic electrolyte further comprises: at least one organic solvent that is dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, gamma -butyrolactone, decanolide, valerolactone, mevalonolactone, caprolactone, dibutyl ether, tetraglyme, diglyme, polyethylene glycol dimethylether, dimethoxyethane, 2-methyltetrahydrofuran, 2,2-dimethyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, cyclohexanone, triethylamine, triphenylamine, triethylphosphineoxide, acetonitrile, dimethylformamide, 1,3-dioxolane or sulfolane; and at least one magnesium compound of formula (R1aMgX), (Mg(X)2), (R2a2Mg) or magnesium perchlorate. (I) is substituted phenyl containing magnesium compounds of formula (m1) or (m2).R1a = 1-10C alkyl or 1-10C amine (both optionally branched) or 6-10C aryl;X = halo;R2a = 1-10C alkyl, 1-10C dialkylboron, 6-12C diarylboron, 1-10C alkylcarbonyl or 1-10C alkylsulfonyl;a1 = halo, -CF3, -CCl3, -NO2, -C(=O)OR, -S(O)2CF3, -S(=O)2C2F5, -S(=O)2OR or -CN; eitherR1, R2, R4, R5 = a1 or 1-20C alkyl or 6-20C aryl (both optionally substituted with a1); orat least one of R1, R2, R4, R5 = a1; eitherR6-R9 = H or halo; orat least one of R6-R9 = halo; andR3 = H (preferred), 1-20C alkyl or 6-20C aryl.The ether solvent is substituted tetrahydrofuran compounds of formula (e1), (R18-O-(CH2-CH2-O)m-R17) (e2), substituted (1,3)dioxolane compounds of formula (e3), substituted (1,4)dioxane compounds of formula (e4), substituted (1,3)dioxane compounds of formula (e5), substituted (1,2)dioxane compounds of formula (e6) or substituted ether compounds of formula (R23-O-R24) (e7), preferably tetrahydrofuran.m = 1-20; andR10-R24 = 1-5C alkyl (optionally substituted with halo). EXAMPLE - Aluminum trichloride was added to anhydrous tetrahydrofuran and stirred until the concentration reached to 0.5 M to prepare a first solution. 2 M 3-Fluorophenyl magnesium bromide dissolved in anhydrous tetrahydrofuran was prepared as a second solution. The first and second solutions were mixed at volume ratio of 1:2 and anhydrous tetrahydrofuran was added to the mixture to obtain organic electrolyte.