Graphitized porous carbon microspheres assembled with carbon black nanoparticles as improved anode materials in Li-ion batteries

We report the facile preparation of graphitized porous carbon microspheres (GPCMs) by the spray drying technique using carbon black (CB) nanoparticles as the primary carbon resource and sucrose as the binder, followed by graphitization at 2800 degrees C. The samples were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, nitrogen adsorption, thermogravimetric analysis, and Raman spectroscopy. It is found that the GPCMs with a size of 5-20 mu m delivered a reversible capacity of 459 mA h g(-1) at the current density of 50 mA g(-1) after 100 cycles, much higher than that of the commercial graphite microspheres (GMs) (372 mA h g(-1)). More importantly, GPCMs exhibited excellent rate performances with a capacity of 338 and 300 mA h g(-1) at the current densities of 500 and 1000 mA g(-1) respectively. superior to those of GMs (200 and 100 mA h g(-1)). The excellent electrochemical properties of GPCMs originate from its unique structure, which is composed of core-shell nanoparticles with the graphitized carbon core derived from CB nanoparticles and the hard carbon shell generated from sucrose, providing more lithium ion storage sites, higher electronic conductivity, and fast ion diffusion. This work opens a simple way to large-scale production of new carbon anode materials with a low cost and good performance for Li-ion batteries.