Currently, the development of lithium–oxygen (air) battery became a hot topic. It is recognised that its specific energy will exceed that of traditional lithium-ion batteries by order of magnitude. The principal element of the lithium–oxygen battery, that is, the active layer of the cathode constitutes a layer of material with a complicated pore structure. During discharge, some electrochemical and chemical processes therein result in the accumulation of lithium peroxide that eventually has been used in the lithium–oxygen battery charging. This power source still suffers from disadvantages, indeed. In this work, computer simulation is used in the elucidating of the effects of the cathode active layer structure on the lithium–oxygen battery overall characteristics during its charging and discharging. A set of obstacles on the way to improvement of the lithium–oxygen battery overall characteristics has been revealed. The obstacles are shown being crucial, they cannot be overcome in terms of current practice of the designing of the lithium–oxygen battery cathode. Therefore, new approaches to the manufacturing of lithium–oxygen battery cathode have to be sought for.