High performance of Co-doped NiO nanoparticle anode material for rechargeable lithium ion batteries

• Co-doped NiO sample was synthesized by low cost facile solvothermal method in polyol medium.
• Co2+ ion substitutes Ni2+ and enhances the concentration of holes to improve p-type conductivity.
• The electronic conductivity of NiO is largely improved through Co2+ doping.
• Co doping significantly suppresses particles agglomeration, which offers a high surface area.
• Greatly enhanced rate capability and excellent cycle retention of Co-doped NiO anode revealed.

A comparative electrochemical study of undoped NiO and Co-doped NiO is performed in order to elucidate the effect of the Co distribution in the crystal lattice of NiO for energy storage applications. Both samples are synthesized using a facile solvothermal strategy and characterized systematically by X-ray diffraction, field-emission scanning electron microscopy, field-emission transmission electron microscopy, X-ray photoelectron spectroscopy and charge/discharge measurements. It is found that doping process does not affect the phase structure of pristine NiO. However, it obviously significantly influences the morphology, suppresses the particles agglomeration and enhances the specific surface area of NiO. More importantly, the substitution of Co for Ni site enhances the p-type conductivity of NiO via the generation of holes. Consequently, the obtained Co-doped NiO anode displays superior Li-battery performance with a large reversible capacity, excellent cyclic performance, and good rate capability in comparison to undoped NiO.