In our work, a series of Li1-xMxCoO2 (M = Na, x = 0-0.05) samples are synthesized by the solid-state calcination route. Electrochemical measurements show that high-rate capacities and high-voltage performances receive obvious improvements with an appropriate content of Na-doping. Specially, the capacity retentions of Li0.97Na0.03CoO2 and LiCoO2 are 65.6% and 62.7% after the 100th cycle at 3.0-4.5 V, respectively. The discharge capacity of Li-0.97 Na0.03CoO2 compared with the pristine electrode LiCoO2 is greatly enhanced from 125 to 135 mAh.g-(1) at the rate of 5 C and 98 to 120 mAh.g(-1) at the rate of 10 C (1C = 140 mA g(-1)) respectively. With the larger radius of Na+ substituted for the smaller radius of Lithorn, it is found that the bond length of Li-O is reduced from 2.0801 angstrom to 2.0781 angstrom, which is helpful for stabilizing the structure of LiCoO2 and improving the cycle capability at high voltages. At the same time, the interplanar distance of Li slabs is expanded from 2.5904 angstrom to 2.59511 angstrom which can accelerate the diffusion of Lithorn and improve the rate capacity. Therefore, Na doped LiCoO2 shows outstanding high-voltage and high-rate performances, and the strategy can also be popularized and applied to other layered cathodes. (c) 2018 Published by Elsevier Ltd.