We report the high capacity, superior rate capability, and excellent cyclic stability of graphene nanosheets (GNs) decorated with Co3O4 nanoparticles as anodes in Li-ion batteries. A pulse microwave-assisted (MA) polyol method (total period: 30 min) is adopted to deposit cobalt oxides onto the GNs in water and ethylene glycol (EG), forming two types of Co3O4@GN hybrids. The selection of solvent in the MA process plays a central role in affecting the crystallinity, dispersion, and particle size of cobalt oxide particles. The resulting Co3O4@GN hybrid, prepared by the MA method in EG, shows a homogeneous dispersion of Co3O4 nanocrystals with an average size of 10 nm. The Co3O4@GN hybrid displays advantages of high reversible capacity, excellent cycleability, and high rate capability. This improved cyclic performance can be attributed to the formation of a three-dimensional GN framework decorated with Co3O4 nanocrystals, leading to fast diffusion of Li ions (diffusion coefficient: 5.82 × 10–12 cm2 s–1) and low internal resistance (equivalent series resistance: 92.2 Ω) determined by electrochemical impedance spectroscopy. With its ease of MA fabrication and good performance, the Co3O4@GN hybrid will hold promise in practical Li-ion batteries.

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