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Graphene Sandwiched Mesoporous Carbon Nanosheets Enable Fast Lithium-Selenium And Lithium-Sulfur Batteries

Posted on:2017-02-23Degree:MasterType:Thesis
Country:ChinaCandidate:H Q LiFull Text:PDF
GTID:2271330485456275Subject:Chemical engineering
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Rechargeable lithium-ion battery has a high energy density, low maintenance costs and low self-discharge ability which attracted considerable attention in academic and business fields, including portable electronic devices, electric vehicles and hybrid electric vehicles potential power supply. Lithium-ion batteries electrode materials are important part of the lithium-ion batteries, because its electrochemical properties of lithium-ion batteries have a key role on the lithium-ion battery performance improvement. Graphene is a two-dimensional hexagonal honeycomb structure composed of a sp2 hybridized carbon atom monolayer. Since 2004, there is a report of the independent existence of graphene which has excellent performance in mechanical, thermal, electrical, optical and other aspects, making it to be a hot point in research fields of chemistry, physics and materials. Recently, graphene in a lithium ion battery electrode materials also inspired a great deal of research interest, graphene derivatives with different oxygen-containing functional groups such as graphite oxide and graphite, etc. can be regarded as 2D material substrate where different nanostructural materials grows and thus a lot of work has been carried out as the electrode material, and has made some progress.Se/Graphene and S/Graphene based mesoporous carbon (Se/GM-C and S/GM-C) composites were prepared by a simple and efficient templating method as cathode composites for Li-Se and Li-S recharge batteries. These composites were characterized using the X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and so on. The electrochemical performances of the Li-Se and Li-S rechargeable batteries were tested by cyclic voltammetry (CV) measurements and capacity measurements. The results of the rate capability are very satisfactory. Even at the current density of 5 C, the Se/GM-C composite can deliver a capacity of 240 mA h g-1 after 500 cycles and at a current of 1 C, the S/GM-C composite can deliver a capacity of 700 mA h g-1 after 200 cycles. The main reason is ascribed to the high conductivity of graphene and the porous structure which can efficiently suppress the dissolution of oxidation products from the cathode materials.
Keywords/Search Tags:graphene, mesoporous, templating method, Li-ion battery
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