| Since the 21st century, the increaing demand of the protable devices and the electric vehicle industry has raised the requirement of the performance of the anodes in lithium-ion battery (LIB). To date, graphite has been used as the conventional anode material in LIBs but the theoretical capacity of the graphite is limited to be 372 mAh g-1. Therefore, many efforts have so far been made to develop other high capacity anodes, including carbon nanotubes, group IV elements, and transition metal oxides and sulfides. Among these materials, transition metal oxides and sulfides have been considered a promising candidate due to its abundance, high theoretical capacity, chemical stability, and low cost. However, pure transition metal oxides and sulfides electrodes have suffered from poor cyclability and a low capacity at high C-rates, which is mainly caused by its low conductivity and morphological collapse by the large volume increase during the charge/discharge cycles. Graphene is a type of carbon material which is one carbon atom thick lattice with a honeycomb network. Because of its high electronic conductivety, large specific area, high tensile strength, thermostablity and chemical resistance, it is great significant in the research and applying of graphene in electrode material for lithium-ion batteries. Graphene based electrode materials usually possess large specific capacity, excellent rate capability, and long cycle life. Graphene based electrode material is promising and would be expected to largely increase the energy density and power density of lithium-ion batteries.In this paper, graphene nanosheets (GNSs) were prepared, and Co3O4-graphene nanocomposites, NiO-graphene nanocomposites, CuO-graphene nanocomposites and SnS2-graphene nanocomposites were synthesized and characterized.Electrochemical performance test results show that Graphene-Based Nanomaterials displayed high cyclability and capacity as anode of lithium ion battery.The reversible capacity of Co3O4-graphene is 906.6 mAh g-1 at 0.1C rate and fades merely 6.9% after 50 cycles. The reversible capacity of is 844.9 mAh g-1 at 0.1 C rate and fades merely 7.1% after 50 cycles. The discharge capacity at 5 C rate is 497.0 mAh g-1. The capacity of CuO-graphene is can maintain between 670 and 700 mAh g-1 at 0.1 C rate in 50cycles.SnS2-graphene nanocomposites are synthesized by a hydrothermal method, and their application as anodes of lithium-ion batteries has been investigated. The reversible capacity is 766 mAh g-1 at 0.2 C rate and maintains at 570 mAh g-1 after 30 cycles.The high Li storage performance of transition metal oxides-GNS nanocomposites can be attributed to GNSs structure and the synergistic effect between transition metal oxides structure and GNSs.GNSs in composites act as flexible two-dimensional supports for anchoring of transition metal oxides, and the transition metal oxides effectively prevent the agglomeration of GNSs.Monocrystalline silicon nanowires and nanosheets are prepared in mass production by the novel electroless etching method. Low-cost silicon powders are used as precursors. The initial capacities of silicon nanowires and nanosheets as lithium-ion battery anodes are up to 4311 and 4426 mAh g-1, respectively. After 10 cycles, the reversible capacity maintains 2318 and 2791 mAh g"1 for nanowires and nanosheets, respectively. The capacity and cyclability of nanosheets is slightly higher than that of nanowires. Such behaviour can be attributed to the two-dimensional nanostructured characteristics, including finite lateral sizes and enhanced open-edges, which can facilitate Li ion diffusion through the active materials and decrease overvoltage associated with the Li-Si alloying reaction, thus driving a faster electrode reaction and providing a higher charge/discharge capacity and cycling stability. |
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