A lithium–oxygen battery with a long cycle life in an air-like atmosphere

A lithium–oxygen battery, comprising a lithium carbonate-based protected anode, a molybdenum disulfide cathode and an ionic liquid/dimethyl sulfoxide electrolyte, operates in a simulated air atmosphere with a long cycle life of up to 700 cycles. Lithium–air batteries could have extremely high energy densities and are therefore attractive successors to the lithium-ion batteries that are currently used in electric vehicles. However, the chemistry involved is complex, with multiple potential (and parasitic) side reactions. These are exacerbated by the relatively low proportion of the 'active' component (oxygen) in a real air mixture as opposed to a pure oxygen feed. This can lead to poor performance relative to the theoretical energy density, as well as degradation with time. Now, Larry Curtiss and colleagues combine appropriate cathodes and electrolytes and protect the lithium anode to create a lithium–air battery that can operate for hundreds of cycles in a realistic air-like atmosphere. This suggests that future development of these batteries may not be restricted to using purified air streams. Lithium–air batteries are considered to be a potential alternative to lithium-ion batteries for transportation applications, owing to their high theoretical specific energy1. 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 electrolyte2,3,4,5. In the presence of nitrogen, carbon dioxide and water vapour, these side reactions can become even more complex6,7,8,9,10,11. Moreover, because of the need to store oxygen, the volumetric energy densities of lithium–oxygen systems may be too small for practical applications12. Here we report a system comprising a lithium carbonate-based protected anode, a molybdenum disulfide cathode2 and an ionic liquid/dimethyl 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.