Enhanced thermal decomposition of carbonates is developed to improve the traditional solid state reaction for the synthesis of ultrafine LiNi1/3Co1/3Mn1/3O2 powders. Controllable activation is obtained by optimizing the mechano-chemical treatment time, which is found to affect lattice structure, morphology and electrochemical properties of the as-synthesized ultrafine LiNi1/3Co1/3Mn1/3O2 powders. The optimal mechano-chemical activation time of 10h results in more stable and integrated structured ultrafine LiNi1/3Co1/3Mn1/3O2 powders with average diameter of 200-500nm, leading to a high reversible capacity of 114.3 and 140.9 mAh g(-1) at 6 C (1620mAg(-1)) in the voltage range of 2.5-4.3 and 2.5-4.5V, respectively. Moreover, the particles exhibit capacity retentions of 80.8% (2.5-4.3V) and 83.3% (2.5-4.5V) at 270mAg(-1) after 200 cycles. Importantly, it is revealed that ball-milling has a positive impact on the calcination process, and the decomposition efficiency is about 35.7% higher compared to ball-milling-free process.Graphical abstractThe LiNi1/3Co1/3Mn1/3O2 powders prepared by enhancing thermal decomposition show a remarkable high temperature electrochemical property. For optimum performance, the time of mechano-chemical activation should be neither too long nor too short. In addition, the calcination process is further studied in order to understand the transformation regularities of the electrode materials. [GRAPHICS] .