Nanocrystalline Li[Li0.26Ni0.11Mn0.63]O2 were easily prepared by using Ni0.15Mn0.85(OH)2 and Li2CO3 as precursors and KCl as melt-salt for the high capacity materials of Li-ion storage. The obtained nanoparticles showed same morphology of polygonal shape and the particle size distribution increased with increasing sinter temperature. The Li[Li0.26Ni0.11Mn0.63]O2 electrode sintered at 800°C for 12h exhibits a reversible capacity of more than 300 mAh g−1 at 0.1C rate between 2V and 4.8V and the capacity retention remains 86% and 90% after 90 cycles at the rate of 0.5C and 1C, respectively. These superior electrochemical performances are discussed in detail and ascribed to the low dimension and well-crystallized particles. The low dimension provides a short diffusion path and fast transport channels for the lithium ion insertion/extraction reactions and the well-crystallized structure restrains the elimination of oxide ion vacancies and metal ions rearrangement during charge–discharge cycling.