Li[Li0.24Mn0.55Co0.14Ni0.07]O-2 cathode materials with controlled spherical morphology and particle size in the range of 5-10 mu m were synthesized by a modified co-precipitation method. The crystal structure of Li[Li0.24Mn0.55Co0.14Ni0.07]O-2 was investigated by Rietveld analysis of structural models using X-ray and neutron powder diffraction data, indicating the presence of Li2MnO3 in the final product. Li[Li0.24Mn0.55Co0.14Ni0.07]O-2 shows low initial irreversible capacity loss (47.2 mAh/g), high reversible capacity (264.6 mAh/g), good capacity retention (90.4% over 50 cycles) and satisfactory rate capability when used as the cathode material in lithium ion batteries. X-ray photoelectron spectroscopy analysis of the pristine, charged and discharged electrodes of Li[Li0.24Mn0.55Co0.14Ni0.07]O-2 reveals that the Mn4+/Mn3+ redox couple participates in the delithiation/lithiation process. Overall, the improved electrochemical performance of the Li[Li0.24Mn0.55Co0.14Ni0.07]O-2 electrode can be ascribed to the controlled and specially designed morphology and the composition of the sample that is produced by the co-precipitation method. (C) 2012 Elsevier B.V. All rights reserved.