A simple and efficient approach was developed to synthesize CuO nanoparticles with improved electrochemical performance. Potassium (K-1)-doped CuO nanoparticles were synthesized by a simple and cost-effective solvothermal method followed by annealing at 500 C for 5 h under air atmosphere. For comparison, an undoped CuO sample was also synthesized under the same conditions. X-ray diffraction analysis demonstrates that the IC ion doping caused no change in the phase structure, and highly crystalline IcCu1 _,01 6 (X = 0.10) powder without any impurity was obtained. As an anode material for a lithium ion battery, the IC-doped CuO nanoparticle electrode exhibited better capacity retention with a reversible capacity of over 354.6 mA h g-1 for up to 30 cycles at 0.1 C, as well as a high charge capacity of 162.3 mAh g-1 at a high current rate of 3.2 C, in comparison to an undoped CuO electrode (275.9 mAh g-1 at 0.1 C and 68.9 mA h g-1 at 3.2 C). The high rate capability and better cycleability of the doped electrode can be attributed to the influence of the IC ion nanostructure on the increased electronic conductivity, diffusion efficiency, and kinetic properties of CuO during the lithiation and delithiation process. (C) 2014 Elsevier B.V. All rights reserved.