Lithium-air batteries are considered to be a potential alternative to lithium-ion batteries for transportation applications, owing to their high theoretical specific energy(1). So far, however, such systems have been largely restricted to pure oxygen environments (lithium oxygen batteries) and have a limited cycle life owing to side reactions involving the cathode, anode and electrolyte(2-5). In the presence of nitrogen, carbon dioxide and water vapour, these side reactions can become even more complex(6-11). Moreover, because of the need to store oxygen, the volumetric energy densities of lithium-oxygen systems may be too small for practical applications(12). Here we report a system comprising a lithium carbonate-based protected anode, a molybdenum disulfide cathode(2) and an ionic liquid/di methyl sulfoxide electrolyte that operates as a lithium-air battery in a simulated air atmosphere with a long cycle life of up to 700 cycles. We perform computational studies to provide insight into the operation of the system in this environment. This demonstration of a lithium-oxygen battery with a long cycle life in an air-like atmosphere is an important step towards the development of this field beyond lithium-ion technology, with a possibility to obtain much higher specific energy densities than for conventional lithium ion batteries.