No. 334: Use exhaust gas to increase the capacity of an air lithium air battery (October 24, 2011)

A research team of Toyota Central R&DLabs discovered that using a mix gas of oxygen and carbon dioxide in place of an oxygen gas for the reaction increased the capacity of an air lithium battery by more than three times. The energy density is 2,360 watt-hour per liter, and the new system can store 6-7 times more electricity than a lithium-ion battery and several score times more electricity than a manganese battery. A battery that utilizes carbon dioxide collected from the outside for the reaction can rarely be found.    

A lithium air battery generates electricity by the reaction between metallic lithium in the negative electrode and oxygen in the air. The research group supplied an oxygen gas mixed with carbon dioxide for the ratio between 30% and 70% to a lithium air battery and found that the capacity of the lithium air battery increased by more than three times, and also learned that the capacity decreased if the ratio of carbon dioxide increased to more than 70%. However, carbon lithium created by the reaction does not create a reaction to generate electricity once it is discharged. Therefore, the research team plans to use the new system for the primary battery that utilizes carbon dioxide in the exhaust gas instead of the secondary battery. It attributes the increased capacity to the slow appearance of carbon lithium. To put the new system into practical application, it is necessary to establish a technology to protect the metallic lithium that reacts with the air.