In this paper, a one-dimensional mathematical model for a non-aqueous lithium–oxygen battery is developed. Unlike previous models, in which all the depositions of the discharge product, lithium peroxide (Li2O2), onto carbon surfaces are treated as continuous solid films, the present work models the formation of Li2O2 as a discontinuous deposit layer. Moreover, the effect of discharge current density on the morphology of the Li2O2 deposit is considered. These treatments enable a more realistic simulation of the effect of the discharge product formation on carbon surfaces. The numerical discharging results are found to be in very good agreement with the experimental data at different current densities including 0.05, 0.1 and 0.2 mA cm−2. The present model is subsequently used to investigate the effect of the design parameters of the cathode (including the electrode thickness, the effective surface area and the cathode utilization) on the discharge performance.