Nanostructured Co3O4 Materials: Synthesis, Characterization, and Electrochemical Behaviors as Anode Reactants in Rechargeable Lithium Ion Batteries

Three distinct Co3O4 nanostructures of nanoparticles, nanocubes, and hierarchical pompon-like microspheres were prepared through facile solution routes. These materials were characterized by XRD, SEM and FESEM, and nitrogen adsorption, and their formation mechanisms were briefly discussed. Their electrochemical behaviors as electrode reactants for lithium ion batteries were evaluated by cyclic voltammograms, electrochemical impedance spectroscopy, and static charge-discharge cycles. Among the three, pompon-like microspheres exhibit the best electrochemistry, revealed by the perfect combination of high discharge capacities and excellent cycling retention. A direct comparison of electrochemical behaviors between these three nanostructures reflects interesting "nanostructure effect", which is reasonably discussed in terms of how particle sizes, nanostructures, and crystallinity of Co3O4 materials function in tuning their electrochemistry. Observations from this research are expected to extend to other transition metal oxides being extensively investigated, and provide valuable guidance for producing practically reliable electrodes based on a series of convertible metal oxides in the future.