In this work, micron- and nano-sized LiNi(0.6)Co(0.2)Mn(0.2)O(2)crystals (M-NCM622 and N-NCM622) are successfully synthesized by molten salt assisted method and stored under ambient environment for 2 days to study the crystal morphologies and stability on electrochemical performance. M-NCM622 shows the well-grown single crystals approximately 2 mu m in size. Because N-NCM622 suffers more surface side reaction than M-NCM622, the former results in more oxygen deficiency and higher deviation of Mn/Ni oxidation state on crystal surface and lower lithium diffusion value (D-Li(+)) than the later. M-NCM622 with homogeneous well-grown single crystals (approximately 2 mu m) delivers 174.1 mAh g(-1)and columbic efficiency of 88% at the first cycle, and remains 78.4%, 91.7%, and 99% of their initial capacities after 100 cycles at 0.2, 1.0, and 5.0 C rates, respectively.