NOVELTY - A sealably-enclosed storage lithium carbon monofluoride-oxygen battery system comprises a lithium metal-containing electroactive anode (10); an electroactive cathode (25) formed of a carbon monofluoride compound; an electrolyte solution formed of an organic solvent and a lithium salt; a casing (5) surrounding the anode, the cathode, and the electrolyte solution; and a port (30) through the casing, where the port selectively allows the flow of an oxygen containing gas (35) into the casing.    USE - As sealably-enclosed storage lithium carbon monofluoride-oxygen battery system (claimed) for converting chemical energy into electric energy; and as energy-storing system and energy power source.    ADVANTAGE - The battery system exhibits high energy storage per unit weight; has improved life of the battery; is cost-effective and shows improved operating efficiency. The combination of cell chemistries results in specific energy for the total cell being higher than for either chemistry by itself. The lithium batteries can provide the most energy for the least weight and volume. The lithium-carbon monofluoride battery has a very high theoretical energy density of 3200 Wh/kg and excellent shelf life and storage characteristics. The lithium-oxygen battery has an even higher specific energy than the lithium-carbon monofluoride battery. The battery has more energy than a lithium-carbon monofluoride battery and retains the excellent initial storage characteristics of a lithium-carbon monofluoride battery.    DETAILED DESCRIPTION - A sealably-enclosed storage lithium carbon monofluoride-oxygen battery system comprises a lithium metal-containing electroactive anode (10); an electroactive cathode (25) formed of a carbon monofluoride compound; an electrolyte solution formed of an organic solvent and a lithium salt; a casing (5) surrounding the anode, the cathode, and the electrolyte solution; and a port (30) through the casing, where the port selectively allows the flow of an oxygen containing gas (35) into the casing. The system further comprises a valve that controls the flow of a gas through the port; a removable covering that prevents the flow of a gas through the port; and a microporous separator (20) that separates the anode from the cathode. INDEPENDENT CLAIMS are included for the following:    (1) an apparatus comprising: an electrochemical battery (1) cell containing: a metal-containing electroactive anode; an electroactive cathode formed of a carbon and a lithium fluoride compound; and an electrolyte solution (15) formed of a solvent and a lithium salt; an electrochemical battery casing encasing the electrochemical battery cell; a port through the electrochemical battery casing to the cathode of the electrochemical battery cell; and a gas control mechanism (33) operatively coupled to the port and comprising an open configuration and a closed configuration, where the gas control mechanism selectively allows the flow of gas into the electrochemical battery cell; and    (2) discharging an electrochemical battery involving: providing a lithium carbon monofluoride-oxygen battery, where the battery comprises: a metal-containing electroactive anode; an electroactive cathode formed of a carbon and a lithium fluoride compound; an electrolyte solution formed of a solvent and a lithium salt; a port through an outer wall of the battery; and a valve coupled to the port and controlling a flow of gas into the battery; closing the valve of the battery to block the flow of gas into the battery; discharging the battery after closing the valve; opening the valve after discharging the battery to expose the cathode to the flow of gas; and discharging the battery after opening the valve.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of an electrochemical battery system.    Electrochemical battery (1)    casing (5)    Anode (10)    Electrolyte (15)    Microporous separator (20)    Cathode (25)    Port (30)    Control mechanism (33)    Pressurized gas cylinder (34)    Gas (35)