The layered rock-salt LiCoO2 granules consisted of the primary nanoparticles were successfully synthesized by one-pot mechanical method without external heating. The sizes of the primary nanoparticle and the granule observed using electron microscopy were 50-200 nm and 20 mu m, respectively. The surface property of the primary nanoparticle was evaluated by STEM-EELS, which revealed that the primary particle possesses the lithium defective part at the surface. The penetration behavior of an electrolyte into the granule was also evaluated by STEM-EDX, which indicated that the electrolyte could not fully penetrate into the granule. The first charge and discharge capacities of Li-ion cell assembled with the synthesized LiCoO2 granules were 140 and 120 mA h/g, respectively. The relationship between the particle structures of the synthesized LiCoO2 granules and the electrochemical properties were discussed. (c) 2014 Published by Elsevier B.V. on behalf of The Society of Powder Technology Japan. All rights reserved