Abstract
The demand for lithium-ion batteries is ascending in the past few years due to the fast growth of a variety of consumer electronics. Although the study of rechargeable lithium batteries has been conducted for more than 40 years, some problems still remain, including reliability of electrodes and capacity of batteries. Therefore, materials with high specific capacity, long cycle life, and good safety are still widely investigated now. In this study, graphene/Fe3O4 sandwich structure was introduced as the anode of lithium-ion batteries and it has the potential to replace graphite, which is used as the anode in commercial lithium-ion batteries, due to the charming features of Fe3O4, such as high specific capacity, low cost, abundant in earth, nontoxicity, good safety, and eco-friendly property. We synthesized Fe3O4 nanoparticles by thermal decomposition method. The as-prepared nanoparticles were examined and analyzed by TEM, XRD and FT-IR. The Fe3O4 nanoparticles were further mixed with CVD graphene to form graphene/Fe3O4 sandwich structure, followed by annealed at 300℃ in Ar atmosphere in a furnace tube. The morphology and phase of graphene/Fe3O4 sandwich structure were observed and investigated by SEM, TEM, and XRD. FT-IR was also used to confirm the absence of oleic acid after annealing. The results of four probe measurement show that the electrons are transported by graphene in the sandwich structure, which is the same as expectation. In order to know the electrochemical properties of graphene/Fe3O4 sandwich structure, coin-type half cells (CR2032) were assembled with the as-prepared graphene/Fe3O4 sandwich structure as the anode in an argon-filled glove box, followed by measured via galvanostatic cycling at 0.1 C rate. The characteristic voltage plateaus of Fe3O4 were appeared in the charge/discharge profiles, but the capacity of graphene/Fe3O4 sandwich structure in this work is lower than the reported data. It is expected that the performance will be further improved if the ratio of Fe3O4 nanoparticles and graphene is adjusted.