New evidence of lithium superoxide dismutation in lithium-air battery cathodes

HERRERA, SANTIAGO E.; DEL POZO, MARIA; TORRES, WALTER R.; CALVO, ERNESTO J.

Congreso; 3rd International Workshop on Lithium, Industrial Minerals and Energy; 2016

The lithium-air battery has been in focus of investigation all around the world over the last year. One of the major debates is about the mechanism of the oxygen reduction reaction that takes place at the cathode side of the promising battery. In this complex reaction, the oxygen coming from the air is electroreduced in the presence of lithium ions to form lithium peroxide (Li2O2) as a final product.In nonaqueous solvents and at specific experimental conditions, the one-electron O2 reduction reaction can take place to produce superoxide radical anion (O2.-) which then diffuses to the solution phase and remains stable. Recently it has been proposed that in Li+ containing solutions, the LiO2 begins to be unstable and can undergo a second electron transfer (surface reaction or dismutate (solution-phase reaction to form Li2O2.The present talk focuses on the disproportionation of LiO2 into insoluble Li2O2 and O2 by adding lithium ions to a tetrabutylammonium-stabilized solution of electrogenerated superoxide by O2 reduction over a Au surface. Quartz crystal microbalance and atomic force microscopy have been employed to find evidence of LiO2 dismutation following the in time incorporation of Li2O2 deposits over the electrode surface at open circuit.