NOVELTY - Lithium-air semi-fuel cell comprises: a lithium metal anode (1) with a metal current collector (7) electro-conductively attached to the anode; an electronically conductive porous carbon cathode (3) coated onto a porous metal current collector (8), where the cathode has inner and outer surface; an electrically non-conductive porous separator, saturated with lithium-ion conductive non-aqueous electrolyte (5), and in contact with the anode and cathode inner surface; and a moisture-proof, electrically insulating housing, encloses anode, cathode and separator with electrolyte.    USE - Used as lithium-air semi-fuel cell.    ADVANTAGE - The lithium-air semi-fuel cell: is efficient, safe and provides high energy density (since the cathode outer surface is protected by oxygen selective permeable membrane and polytetrafluoroethylene coated fiberglass cloth); also exhibits high flexibility (due to the flexibility of materials absorbed on carbon based cathode), thus permits various designs or configurations in manufacturing, e.g. prismatic and cylindrical constructions; and utilizes the cathode coated with oxygen selective permeable membrane and polytetrafluoroethylene coated fiberglass cloth, which prevents the components of the internal aprotic electrolyte solution from evaporating into the atmosphere and atmospheric water vapor from entering the cell.    DETAILED DESCRIPTION - Lithium-air semi-fuel cell comprises: a lithium metal anode (1) with a metal current collector (7) electro-conductively attached to the anode; an electronically conductive porous carbon cathode (3) coated onto a porous metal current collector (8), where the cathode has inner and outer surface; an electrically non-conductive porous separator, saturated with lithium-ion conductive non-aqueous electrolyte (5), and in contact with the anode and cathode inner surface; a moisture-proof, electrically insulating housing, encloses anode, cathode and separator with electrolyte, where the housing has an opening facing the cathode outer surface and the opening is covered by an oxygen selective permeable, moisture-proof membrane of polytetrafluoroethylene coated fiberglass cloth and hermetically sealed to housing, and the current collectors exits from the housing in hermetically sealed manner, and are electrically insulated from the housing. INDEPENDENT CLAIMS are also included for:    (1) a cathode for lithium-air semi-fuel cell, comprising inner and outer surface in relation to the cell, and where the cathode includes an oxygen selective permeable membrane made of polytetrafluoroethylene coated fiberglass cloth and facing the outer surface; and    (2) an oxygen selective permeable membrane made of polytetrafluoroethylene coated fiberglass cloth, which is useful for protection of lithium-air semi-fuel cells from water, and also retards egress of electrolyte from the semi-fuel cells.    DESCRIPTION OF DRAWING(S) - The figure shows schematic, sectional side view of the lithium-air semi-fuel cell.    Lithium metal anode (1)    Porous carbon cathode (3)    Lithium-ion conductive non-aqueous electrolyte (5)    Anode metal current collector (7)    Porous metal cathode current collector (8)