NOVELTY - The bifunctional air electrode comprises a current collector having a corrosion-resistant outer layer and a conductive inner layer, an air permeable, hydrophobic catalytic membrane, an oxide formed on the current collector, and a porous carbon-based coating on the current collector. The corrosion-resistant outer layer has a greater corrosion resistance than the inner layer, and the conductive inner layer has a higher level of electrical conductivity than corrosion-resistant outer layer. The conductive inner layer is sandwiched within or coated by the corrosion-resistant outer layer.    USE - The bifunctional air electrode is useful for a metal-air battery or battery cell (all claimed), where the electrode is non-corroding electrically rechargeable bifunctional air electrode.    ADVANTAGE - The porous, thin and lightweight bifunctional air electrode exhibits improved stability, water wettability and performance characteristics and excellent mechanical strength, and is capable of reducing oxygen during cell discharge and oxidizing water to form oxygen gas during cell charge.    DETAILED DESCRIPTION - The bifunctional air electrode comprises a current collector having a corrosion-resistant outer layer and a conductive inner layer, an air permeable, hydrophobic catalytic membrane, an oxide formed on the current collector, and a porous carbon-based coating on the current collector. The corrosion-resistant outer layer has a greater corrosion resistance than the conductive inner layer, and the conductive inner layer has a higher level of electrical conductivity than the corrosion-resistant outer layer. The conductive inner layer is sandwiched within or coated by the corrosion-resistant outer layer. The current collector has a dual function of acting as a protective coating and acting as a catalyst. The fullerenes are electrochemically deposited from either an aqueous or non-aqueous solvent on the current collector, and the carbon nanotubes (CNT) are deposited on the current collector. A glassy carbon is coated on a substrate with a resin to form glassy carbon when and pyrolyzed at the proper temperature which is usually 1000 degrees C or higher or lower in an inert atmosphere or vacuum. The corrosion-resistant outer layer comprises a powder coating of a corrosion resistant material in a coating material that coats the conductive inner layer. The coating material is made of plastic or epoxy. During electrical charging under anodic potentials, an oxygen evolution is favored. The catalytic membrane acts as a catalyst to affect the reduction of oxygen or the generation of oxygen from water. The catalytic membrane includes porous, air and oxygen permeable, silicone rubber, and is an air permeable and hydrophobic membrane. INDEPENDENT CLAIMS are included for:    (1) a metal-air battery or battery cell; and    (2) a method for forming a bifunctional air electrode for a metal-air battery.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic side view of an air electrode.    Conductive current collector (101)    Hydrophobic, water repelling region (102)    Hydrophilic, water attracting region (103)    Air-facing side (104)    Electrolyte-facing side. (105)