The SEI layer formed on lithium metal in the presence of oxygen: A seldom considered component in the development of the Li-O2 battery

► The presence of O2 influences the composition of the SEI on Li of the Li-O2 battery. ► The SEI on Li anode of the Li-O2 battery is unstable and changes during the cycling. ► LiPF6 and PC decompose on the surface of the Li and contribute in formation of the SEI. ► Decomposed Kynar binder (degraded on the cathode) was observed on the surface of Li. ► Oxygen increases the resistance of the cells and influences the lithium stripping and plating.