A facile polyol-assisted pyro-synthesis method was used to synthesize Co3O4 nanoparticles embedded into carbon matrix without using any conventional carbon source. The surface analysis by scanning electron microscopy showed that the Co3O4 nanoparticles (~20 ± 5 nm) are tightly enwrapped within the carbon matrix. CHN analysis determined the carbon content was only 0.11% in the final annealed sample. The Co3O4@carbon exhibited high capacities and excellent cycling performance as an anode at various current rates (such as 914.4 and 515.5 mAh g−1 at 0.25 and 1.0 C, respectively, after 50 cycles; 318.2 mAh g−1 at a high current rate of 5.0 C after 25 cycles). This superior electrochemical performance of the electrode can be attributed to the various aspects, such as, (1) the existence of carbon matrix, which acts as a flexible buffer to accommodate the volume changes during Li+ ion insertion/deinsertion and facilitates the fast Li+ and electron transfer and (2) the anchoring of Co3O4 nanoparticles within the carbon matrix prevents particles agglomeration.
