Li/O-2 batteries draw much attention due to its outstanding theoretical specific energy, but the value of practically achievable specific energy is still under the question. In this paper we employ a numerical model of Li/O-2 cell, which takes into account mass transport processes, to simulate non-uniform product precipitation at different discharge current densities in acetonitrile, dimethyl sulfoxide and 1,2-dimethoxyethane-based electrolytes. Even for 1,2-dimethoxyethane, which has the highest oxygen mobility and solubility, oxygen transport restrictions at 1 mA/cm(2) lead to cell-level specific energy of about 650 Wh/kg if a pure oxygen is supplied to the cell. Finally, in order to assist the ongoing search for new cathode materials, which can be alternative to carbon, we also investigate the effect of electrode material density on cell-level specific energy and show that materials with densities up to 10 g/cm(3) can be used without serious penalty to the specific energy. (C) 2015 Elsevier B.V. All rights reserved.