NOVELTY - The high voltage rechargeable magnesium cell (5) comprises an anode can/housing, a magnesium metal anode positioned proximate to the anode can, a high voltage electrolyte positioned proximate to the anode, a metal oxide cathode positioned proximate to the high voltage electrolyte, a cathode current collector (16) positioned proximate to the cathode, and a cathode can/housing positioned proximate to the cathode current collector. The cathode can/housing includes a layer (21) of inert material such as carbon or a noble metal, and is isolated from the electrolyte and metal oxide cathode.    USE - The high voltage rechargeable magnesium cell is useful in an electrically-powered apparatus such as consumer electronic devices, medical devices and electric or hybrid vehicles.    ADVANTAGE - The high voltage rechargeable magnesium cell exhibits improved capacity density.    DETAILED DESCRIPTION - The high voltage rechargeable magnesium cell (5) comprises an anode can/housing, a magnesium metal anode positioned proximate to the anode can, a high voltage electrolyte positioned proximate to the anode, a metal oxide cathode positioned proximate to the high voltage electrolyte, a cathode current collector (16) positioned proximate to the cathode, and a cathode can/housing positioned proximate to the cathode current collector. The cathode can/housing includes a layer (21) of inert material such as carbon or a noble metal, and is isolated from the electrolyte and metal oxide cathode. The magnesium cell has a multi-cycle charge voltage of 3 volts and a reversible discharge capacity. The cathode current collector is formed of carbon, carbon paper, carbon cloth, a metal, a noble metal mesh or a foil. The anode electrode and the cathode electrode include a binder, an electrically conducting material, and an active material. The high voltage electrolyte includes a separator, and is stable against oxidation.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a high voltage rechargeable magnesium cell.    Rechargeable magnesium cell (5)    Electrolyte layer (12)    Cathode current collector (16)    Inert material layer (21)    Sealing gasket. (22)