Charge-discharge behavior of SONY 18650 lithium-ion batteries for aerospace applications was simulated under low-earth-orbit (LEO) conditions, by using a first-principles based mathematical model. The model determines the capacity fade on the basis of the irreversible loss of active lithium ions due to electrolyte reduction. The capacity fade during LEO cycling was studied for 5 years of continuous operation with 20% depth of discharge as a function of the cycling parameters such as the end of charge voltage and the charging rate. (c) 2006 Elsevier B.V. All rights reserved.