Controllable synthesis of graphene nanoscroll-wrapped Fe3O4 nanoparticles and their lithium-ion battery performance
In this work, a series of graphene nanoscroll (GNS)-wrapped Fe3O4 nanoparticles (NPs) composites (denoted as Fe3O4@GNS) are prepared by cold quenching of mixed suspensions of water-dispersible Fe3O4 NPs and graphene oxide (GO) with different mass ratios in liquid nitrogen followed by a low-temperature thermal reduction. In all samples, it is interesting that Fe3O4 NPs are able to be in situ encapsulated completely in GNSs, forming a three-dimensional network consisting of a fiber-like structure. The amount of Fe3O4 NPs wrapped with GNSs is in proportion to the mass ratio between Fe3O4 NPs and GO in the initial mixed suspension. As a new anode material of lithium ions batteries (LIBs), these Fe3O4@GNSs exhibit outstanding Li-ion storage characteristics. Among them, the Fe3O4@GNS (Fe3O4 : GO = 2 : 1) electrode shows the best electrochemical properties, including excellent cycling stability with a reversible capacity of 1172 mA h g−1 over 200 cycles at 100 mA g−1 and 525 mA h g−1 over 1000 cycles at 2 A g−1, as well as superior rate performance with a reversible capacity of 648 and 480 mA h g−1 at 2 and 5 A g−1, respectively. Such high performance is very close to the novel hybrid structure of Fe3O4@GNS as well as the optimal ratio between Fe3O4 and GO.