Enhancing the electrochemical performance of lithium-ion batteries using porous Fe3O4/carbon composite microspheres

Abstract

In this study, we proposed the fabricating method for the porous Fe3O4/C composite microspheres with introduction of the different amount of active materials in carbon matrix. Monodispersed porous PS microspheres have different pore volume were synthesized by seeded polymerization under different content of diluent. In order to carbonize and introduce ferrous (Fe2+) and ferric (Fe3+) ions, porous PS microspheres were sulfonated by sulfuric acid. The difference of the total pore volume and specific area of porous sulfonated-PS microspheres was measured by BET and BJH measurements. Fe3O4 nanocrystals were formed in pores and surfaces of the porous sulfonated-PS microspheres by a simple wet chemical method. Black colored-powder was obtained and their intrinsic porous structure was still maintained after heat treatment. Porous structure and existence of Fe3O4 nanocrystals in carbon matrix were confirmed by scanning electron microscopy, focused ion beam-scanning electron microscopy, X-ray diffraction and EDX-mapping. When the composite electrodes were tested for the anode material in a Li-ion half-cell, the porous Fe3O4/C composite microspheres contain higher amount of Fe3O4 nanocrystals has demonstrated not only higher reversible capacity but also excellent cycling performance.