Synthesis and electrochemical performance of reduced graphene oxide/maghemite composite anode for lithium ion batteries

Reduced graphene oxide (rGO) tethered with maghemite (gamma-Fe2O3) was synthesized using a novel modified sol-gel process, where sodium dodecylbenzenesulfonate was introduced into the suspension to prevent the undesirable formation of an iron oxide 3D network. Thus, nearly monodispersed and homogeneously distributed gamma-Fe2O3 magnetic nanoparticles could be obtained on surface of graphene sheets. The utilized thermal treatment process did not require a reducing agent for reduction of graphene oxide. The morphology and structure of the composites were investigated using various characterization techniques. As-prepared rGO/Fe2O3 composites were utilized as anodes for half lithium ion cells. The 40 wt.%-rGO/Fe2O3 composite exhibited high reversible capacity of 690 mA h g(-1) at current density of 500 mA g(-1) and good stability for over 100 cycles, in contrast with that of the pure-Fe2O3 nanoparticles which demonstrated rapid degradation to 224 mA h g(-1) after 50 cycles. Furthermore, the composite showed good rate capability of 280 mA h g(-1) at 10C (similar to 10,000 mA g(-1)). These characteristics could be mainly attributed to both the use of an effective binder, poly(acrylic acid) (PAA), and the specific hybrid structures that prevent agglomeration of nanoparticles and provide buffering spaces needed for volume changes of nanoparticles during insertion/extraction of Li ions. (C) 2012 Elsevier Ltd. All rights reserved.