The effect of electrode density on safety was investigated with Li[Ni0.8Co0.15Al0.05]O-2 (NCA) electrodes in the presence of 1.0M LiPF6 EC:DEC (1: 2 v/v ratio) using accelerating rate calorimetry (ARC). The densities of the electrodes were 1.6 g/cm(3), 2.0 g/cm(3), and 2.3 g/cm(3), respectively. Denser electrodes showed inferior thermal stability compared to porous electrodes. ARC tests with ground electrode powder in the presence of EC: DEC (1: 2 v/v) solvent, with and without LiPF6 salt, show that the denser electrode has lower thermal stability because it contains less LiPF6. A charged NCA electrode in 0.7M LiBOB EC: DEC (1: 2 v/v) electrolyte shows worse thermal stability than in 1.0M LiPF6 EC: DEC (1: 2 v/v) electrolyte. These results may be useful for researchers and engineers interested in designing safe electrodes using NCA positive electrode material. (C) 2013 The Electrochemical Society. All rights reserved.