Preparation And Modification Of Fe₃O₄as Anode Materials For Lithium Ion Batteries

In recent years, the development of nanoscience and nanotechnology has been widely penetrated into many other disciplines; one of the most typical examples is the design, synthesis and development of new nanomaterials, and application in lithium ion battery. Compared with the commercial graphite, Magnetite (Fe3O4) has received considerable attention due to its low cost, non-toxicity, long life cycles and the high theoretical capacity (928mAh/g). Unfortunately, Fe3O4has a severe volume variation during the insertion and extraction of lithium ions, which would highly affect the stability of the LIBs performance. Recently, novel Fe3O4-based nanostructures and carbon encapsulated Fe3O4are reported and its electric measurement revealed the oxides with both of the modifacations had good LIBs performances.Porous and hollow Fe3O4@C spheres, N-doped carbon coated Fe3O4and Fluorine-doped, carbon-encapsulated hollow Fe3O4were synthesized by a facile method. These nanostructures were characterized by SEM, TEM, XRD, HRTEM, EDS, Electrochemical tests and so on. Then the electrochemistry performance of the nanostructures were investigated. The work includes three aspects:1. The carbon coating porous nanospheres (P-Fe3O4@C) was successfully synthesized by wrapping glucose coated porous Fe3O4spheres with pyrolysis treatment at500℃and used for anode materials for Lithium-ion batteries application. Compared with the pure porous Fe3O4(p-Fe3O4, hollow Fe3O4(h-Fe3O4and carbon coating hollow Fe3O4(h-Fe3O4@C), the as-prepared composite exhibited much better electrochemical performance with a high reversible capacity of600mAh/g after300cycles at a current rate of1C.2. We designed a novel structure nanomaterial using carbon and N-doped carbon derived from cyclooctatetraene and PEI to carry Fe3O4nanospheres (Fe3O4@C or Fe3O4@N-doped carbon). Compared with carbon coated Fe3O4the N-doped carbon Fe3O4exhibited a more stable electrochemistry performance. 3. Herein we first report the design and synthesis of fluorine-doped, carbon-encapsulated hollow Fe3O4spheres (h-Fe3O4@C/F) through mild heating of polyvinylidene fluoride (PVDF)-coated hollow Fe3O4spheres. The spheres exhibit enhanced cyclic and rate performance. The as-prepared h-Fe3O4@C/F shows significantly improved electrochemical performance...