Poly-assisted template-free synthesis of novel double-shelled Co3O4 yolk–shell submicrospheres with excellent electrochemical properties

Abstract

Novel double-shelled Co₃O₄ yolk–shell submicrospheres were successfully synthesized via a poly-assisted template-free solvothermal method and a subsequent high heat-treatment process. Before being calcined, the obtained solid spheres were amorphous and the surfaces of the precursors were smooth. The morphology and phase of the products were characterized using several physical analysis techniques, including powder X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The LAND cell test system revealed the electrochemical properties of the final products. The as-prepared double-shelled yolk–shell submicrospheres showed a remarkable initial specific discharge capacity of about 1634 mA h g⁻¹. From the 2nd cycle to the 70th cycle, the specific discharge capacity of the double-shelled yolk–shell submicrospheres varied from 1283.2 to 1091 mA h g⁻¹ with a retention rate of around 85.03%, corresponding to a fading rate of 2.17% per cycle. Moreover, a possible growth mechanism of the yolk–shell spheres from the solid spheres precursor was also proposed.