Electrochemical synthesis of rGO-Fe3O4 complex and its application to lithium-ion batteries

초록

Lithium-ion batteries (LIBs) with a carbonaceous anode and lithiated metal oxide cathode have been widely used for various applications from portable electronics to electric vehicle (EV) industry owing to their large advantages such as high operating voltage, energy density, and long-life time. Graphite, which is the most widely used as an anode material in LIBs, has several advantages including low production cost, abundant, and charge?discharge cycle stability. However, a low theoretical capacity (372 mAh g-1), sluggish Li+ diffusion coefficient, and safety issue of graphite are considered the limiting factor to meet the growing demand for energy density that arise in large-scale energy storage systems (ESS) and EV. In this regard, among the numerous studies on a new anode material that will replace graphite, transition metal oxides are regarded as one of the most promising candidates due to their intrinsic chemical or physical properties such as high theoretical capacity, environmental friendliness, and low cost. However, the limitations of transition meal oxides such as poor conductivity, low diffusion coefficient, and formation of a thick SEI layer should be overcome by fabricating transition metal oxide-conductive agent complex via different approaches including as chemical vapor deposition (CVD) , spray coating, and wet coating. In this study, we design and construct rGO-Fe3O4 complex, in which nanosized Fe3O4 are evenly decorated on rGO sheet via electrochemical route as a volume expansion regulated binder-free anode electrode for LIBs. The morphological and physicochemical properties of the prepared composites are investigated by various analysis methods ? SEM, TEM, XRD, XPS, and Raman spectroscopy. In addition, electrochemical measurements for cyclic voltammetry (CV), charge-discharge profile are conducted in CR2032 con-type half cell with a pure metallic lithium as counter electrode using a glass fiber separator in 1 M LiPF6 electrolyte.