Nanoparticle-nanorod core-shell LiNi0.5Mn1.5O4 spinel cathodes for Li-ion batteries were prepared using a hollow MnO2 precursor. The core and shell parts consisted of nanoparticle (similar to 100 nm) and nanorod assemblies, respectively. The core-shell cathode exhibited greatly improved discharge capacities compared to nanoparticles prepared by a sol-gel method. The core-shell spinel exhibited discharge capacities of 121 and 100 mAh/g at 0.1C and 7C rates, respectively, whereas a spinel cathode prepared by a sol-gel method exhibited 99 and 80 mAh/g at those respective rates. In addition, the core-shell spinels demonstrated an energy density value that was enhanced by 52% to 1.6 Wh/cm(3) compared to an analogous sample prepared by a sol-gel method, which showed a value of 0.9 Wh/cm(3). (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3428706] All rights reserved.