Researchers clear away obstacle for lithium-air batteries

May 10, 2016 // By CHRISTOPH HAMMERSCHMIDT
Lithium-air batteries are one of the most likely candidates as the successor for today’s lithium-ion technology in electric vehicles: They can store up to ten times the energy of a lithium-ion battery, significantly extending the driving range. However, the lithium-air technology still poses a number of challenges to engineers. The most significant one: Lithium-air batteries are ageing very fast. Scientists now have found out why.

In the lithium-air battery, the energy density is, at least in theory, ten times higher compared to conventional lithium-ion batteries. In addition, in this technology porous carbon particles replace the heavyweight electrodes made by the oxides of transition metals and thus enables the design of lightweight batteries. While this looks like a perfect combination, today’s lithium-air prototype batteries exhibit a massive drawback: They tend to drastically lose their performance already after a few charging cycles, and the electrodes disintegrate. Scientists from the Munich Technical University (TUM) and the Jülich Research Center now have found the reason for this behavior: During the charging process, highly reactive singlet oxygen is generated. This oxygen corrodes surrounding materials within the fraction of seconds, explains doctoral candidate Johannes Wandt from TUM.

There are two reasons why the scientific community did not find out earlier the reason for the short live cycle of lithium air batteries: One is the rather complex experimental setup. And the other one is that there has been a miscalculation in the scientific literature that kept scientists from searching in the right place, Wandt assumes.