LiCo0.3RhxNi0.7-xO2 (0 < x < 0.003) cathodes were synthesized by a sol-gel method. All samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical performance. The results show that Rh-doping not only increases the initial charge-discharge capacities of LiCo0.3Ni0.7O2 but also improves the capacity retention. The LiCo0.3Rh0.002Ni0.698O2 has the excellent electrochemical performance. After 50 cycles, the discharge capacity of UCo(0.3)h(0.002)Ni(0.698)O(2) is 185.3mAh g(-1) at 0.15C in 3.0-4.5 V, which is 93.7% of the first discharge capacity. Meanwhile, the Rh-doping exhibits the effect of suppressing the impedance rise during cycling of Li/LiCo0.3Ni0.7O2 and promotes the diffusion of Li+ in LiCo0.3Ni0.7O2. Moreover, Rh-doping suppresses the phase transitions that usually occur in LiNiO2 during cycling and improves the charge-discharge reversibility of Li/LiCo0.3Ni0.7O2. Thermal stability of the charged cathodes is also improved by Rh-doping, which is possibly attributed to the lowered oxidation ability and the enhanced structure stability of those delithiated Rh-doped cathodes during cycling. (c) 2007 Elsevier B.V. All rights reserved.