Graphene Oxide Electrochemical Property And Its Application In Lithium-ion Battery

The lithium-ion battery has changed our life ever since its invention. However, the development of Lithium-ion battery has fallen behind people’s demand for higher energy density and higher power density battery. My research is focused on anode materials of Lithium-ion battery especially graphene-based materials, which can largely determine the electrochemical performance of battery. First we use facile steps to increase the Li-ion insertion sites, namely adopt some filler to make graphene composites to increase the specific capacity of graphene by decreasing the interlayer aggregation; second we make pathways for ion transportation on the graphene sheet meantime keep graphene unique structure; the pathways serve as the short-cut for Li-ion/electron diffusion. The detailed methods are as follows:(1) The composite of ferrocene and graphene oxide(GO)(ferrocene/GO) was prepared through a solvothermal procedure. The raw materials are ferrocene, graphene oxide and ethanol. The composite keeps the planar structure of graphene. The anode made up of this composite shows the Columbic Efficiency ~87% at the first discharge/charge cycle. The oxygen-containing groups on GO serve as nucleation sites for ferrocene clusters, and the ferrocene clusters can cut off the aggregation of graphene, beside the ferrocene clusters can provide the Li-ion inserting sites.(2) The raw materials are ferrocene, graphene oxide and ethanol. The composite of ferrocene and GO(ferrocene/GO) was prepared through a solvothermal procedure. Then the as-obtained composite was put into a quartz tube and annealed at 900°C for 4h in a flow of Ar and subsequently was washed by acid. The as-generated nanoporous graphene sheets show the morphology of graphene with nanopores ~40nm attached on the graphene sheet. The anode made up of nanoporous graphene sheet shows a specific capacity of 980.1 mAhg-1 at a current density of 0.2 A g-1 for the first cycle, higher than most reported literatures. When the current densities of charge/discharge increased to 0.5, 1, 2, 5, and 10 A g-1 sequentially, the as-measured specific capacities were 717.1, 626.1, 518.4, 429.9 and 346.5 mAhg-1, respectively, exhibiting a good rate capability. Pronouncedly, after 100 cycles of discharge/charge, the specific capacity of the coin cell still retained at 850 mAhg-1, and the CE was up to 95.2%. This reflects the good cycling stability of the anode prepared with nanoporous graphene sheets.