Аннотация:High-energy lithium-oxygen batteries development bogged down as it faced numerous challenges including capacity limitations due to electrode surface passivation by the discharge product Li2O2. As the passivation rate and intensity are dependent on the deposit morphology, we focus here on the mechanisms governing Li2O2 formation within the porous cathode. We report evidences of homogeneous nucleation of Li2O2 crystallites and its further assembly in the bulk of electrolyte solution in DMSO, which possess high donor number. After careful estimation of the superoxide ion concentration distribution within phenomenological model, we found that the high stability of superoxide ions formed during ORR towards disproportionation and sufficient diffusivity of (0.5-1.2) 10-6 cm2/s enable Li2O2 nucleation and crystallization not only at the surface but also in the electrolyte, and the reaction zone spreads over all internal space of porous electrode. High initial supersaturation promotes homogeneous nucleation of Li2O2 nanoplates, which can be instantly assembled into mesocrystals also in the solution bulk. The conclusions are supported by operando SAXS/WAXS and morphology observations. Although homogeneous nucleation can be not dominant, it is important for gaining high capacity in Li-O2 batteries.