Preparation And Electrochemical Performance Research Of Carbon Coated Metal Oxide/metal Composite Materials

With the rapid development of economy and the society,higher requirements putted forward for the commercial lithium-ion batteries performance.High specific energy commercial lithium-ion batteries(LIBs)application prospects are particularly prominent due to the emergence of portable electronic products(such as mobile phones,laptops and digitals),electric vehicles and hybrid electric vehicles.Since 2010,sodium ion batteries(NIBs)as substitutes for lithium-ion batteries have quickly become the focus of attention in terms of their low cost,wide distribution and chemical storage mechanisms similar to lithium.For these reasons,the recent researches of lithium/sodium ion battery are increasing.The canode/anode materials,the separator and the electrolyte all affect the performance of the lithium/sodium ion batteries,and the anode electrode materials play an important role,especially.The current researches of the cathode materials in lithium/sodium ion battery have made a good progress;and the researches of the anode materials are also in full swing in progress.The development of nanostructured metal oxide/metal composites of the anode materials becomes the main hotspot in the future.Based on the above topic,the main research objects of this paper are as follows:(1)Preparation of carbon coated ferric oxide nanocomposites and their performances in lithium batteryFe2O3 has a high theoretical specific capacity(?1000 mA h g-1).In our work,the spindle-like Fe2O3 is wrapped as a core in a carbon shell to produce Fe2O3@NC structured nanocomposites(yolk-shell).In case the unique design of the composite effectively buffers the structure pulverizing caused by the volume expansion of the Fe2O3 during the charging and discharging process and reduces the direct contact between the electrolyte and the Fe2O3.On the other hand,the highly conductive carbon shell increased the electrochemical stability of the material.Therefore,the material exhibits high specific capacity and coulombic efficiency,as well as cycling stability.(2)Preparation of carbon coated metallic antimony composites and their performances in sodium batteryIn this work,we successfully prepared a two-dimensional nitrogen-doped carbon-metal antimony composite film assembled by using graphene and(L)-tartaric acid as precursors for carbon materials and antimony trichloride as a metal source,in which the nano-metal antimony is completely wrapped in the carbon material.Due to its unique hierarchical structure and high specific surface area,this design not only improves the electron transfer and sodium ion transport,but also reduces the possibility of material being pulverized during cycling.Therefore,the material exhibits superior performance for sodium-ion batteries.