Controllable synthesis of graphene nanoscroll-wrapped Fe3O4 nanoparticles and their lithium-ion battery performance

Abstract

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.