Synthesis of carbon-coated Co3O4 composite with dendrite-like morphology and its electrochemical performance for lithium-ion batteries

Carbon-coated Co3O4 microparticles (Co3O4@C) with dendrite-like morphology are prepared by a low-temperature hydrothermal method and subsequent C2H2 chemical vapor deposition (CVD) for the first time. The synthesized precursor Co3O4 has a size of 8-10 mu m, which is assembled by lots of aligned Co3O4 wire with 4-5 mu m in length. After carbon coating, Co3O4 microparticles were proved to be coated in amorphous carbon of similar to 10 nm. A plausible formation process of the dendrite-like Co3O4 and Co3O4@C is proposed based on the morphology and structure characterizations of the materials. As an anode material for lithium-ion batteries, the Co3O4@C composite electrode exhibits higher reversible capacity and better cycling performance than the unmodified Co3O4 electrode. The reversible capacity of the Co3O4@C composite after 40 cycles is 500 mAh g(-1), much higher than that of Co3O4 (148 mAh g(-1)). Electrochemical impedance spectra and cyclic voltammogram indicate that the carbon layer coated on Co3O4 by CVD can improve the electrochemical activity and enhance the reversibility of Co3O4 during charge/discharge cycles.