Influence of Gold Nanoparticles Anchored to Carbon Nanotubes on Formation and Decomposition of Li2O2 in Nonaqueous Li-O2 Batteries

Gold nanoparticles (AuNPs) anchored to vertically aligned carbon nanotubes (VACNTs) act as additional nucleation sites for the Li2O2 growth, leading to the decreased size while increased density of Li2O2 particles in process of discharge. Correspondingly, at the deep discharge to 2.0 V the batteries show increased specific capacity. Upon charge, the AuNPs exhibit promotion effect on the Li2O2 decomposition by improving the conduction property of the discharge-formed particles, rather than by imposing the conventional electrocatalytic effect on the oxygen evolution reaction. Moreover, the AuNPs show promotion effect on decomposition of carbonate species arising from the side reactions. These effects consequently lead to the reduced charge overpotentials and extended cycle operation of the batteries. The results here provide a new as well as clear picture on the role of incorporated AuNPs in the Li2O2 formation and decomposition, which would be helpful for better understanding and constructing of high-performance air cathodes.