title: Graphene-encapsulated hollow Fe₃O₄ nanoparticle aggregates as a high-performance anode material for lithium ion batteries.
abstract: Graphene-encapsulated ordered aggregates of Fe(3)O(4) nanoparticles with nearly spherical geometry and hollow interior were synthesized by a simple self-assembly process. The open interior structure adapts well to the volume change in repetitive Li(+) insertion and extraction reactions; and the encapsulating graphene connects the Fe(3)O(4) nanoparticles electrically. The structure and morphology of the graphene-Fe(3)O(4) composite were confirmed by X-ray diffraction, scanning electron microscopy, and high-resolution transmission microscopy. The electrochemical performance of the composite for reversible Li(+) storage was evaluated by cyclic voltammetry and constant current charging and discharging. The results showed a high and nearly unvarying specific capacity for 50 cycles. Furthermore, even after 90 cycles of charge and discharge at different current densities, about 92% of the initial capacity at 100 mA g(-1) was still recoverable, indicating excellent cycle stability. The graphene-Fe(3)O(4) composite is therefore a capable Li(+) host with high capacity that can be cycled at high rates with good cycle life. The unique combination of graphene encapsulation and a hollow porous structure definitely contributed to this versatile electrochemical performance.
authors: Department of Chemical & Biomolecular Engineering, Faculty of Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore.
authors: Dongyun
authors: D
authors: Chen
authors: Ge
authors: G
authors: Ji
authors: Yue
authors: Y
authors: Ma
authors: Jim Yang
authors: JY
authors: Lee
authors: Jianmei
authors: J
authors: Lu
mesh_terms: D011211:Electric Power Supplies; D004566:Electrodes; D052203:Ferrosoferric Oxide / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D008094:Lithium / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D016062:Porosity; D014961:X-Ray Diffraction
chemical_list: D007477:Ions; D006108:Graphite; D008094:Lithium; D052203:Ferrosoferric Oxide