Preparation And Electrochemical Properties Research On Ni/C Composites

Since fullerenes and carbon nanotubes were prepared successfully, carbon materials have aroused widespread concern. This is mainly because the outstanding performance of carbon materials makes them be used widely. Recently, carbon matrix composite materials have got more and more attention, because carbon matrix composites not only reserve the excellent properties of carbon materials, at the same time, also makes up for the shortcomings of them in some way. Significantly improvement of the performance of carbon composite material has made it get great potential application value. As to metal/carbon composite materials, because of the addition of metal, the properties of composite materials such as conductivity, specific capacity have been improved greatly, at the same time, the properties of carbon material such as stability a variety of excellent performance also are reversed. Therefore it have been applied in many aspects, such as electrode materials,catalyst support, adsorption, hydrogen storage and environmental protection, and makes them have great application prospect and potential value in the field of modern materials.A variety of methods can be used to prepare carbon materials, such as reduction method, chemical vapor deposition method, template method and arc discharge method, etc., but they have many shortcomings such as poor safety, high energy consumption, complex operation, low production rate and high cost. Hydrothermal carbonization is a low cost preparation method of carbon materials, it has less energy consumption, easy to operation, mild reaction, high product purity, safety and eco-friendly. Many kinds of raw material can be used to prepare carbon materials such as glucose, sucrose and cellulose, etc.. Cellulose that composes of glucose, with an very high degree of polymerization, exists in all kinds of biomass in great quantities and unusually rich in content in the nature. Because of its advantages of cheap, easy obtained and high purity, cellulose has considerable economic development value and research practical value.Using the biomass materials-cellulose as raw material, this project prepared carbon materials by hydrothermal carbonization, then, Ni/C composite materials also ware prepared by adding Ni metal. We detailedly study preparation process conditions, the structure and electrochemical performance of carbon materials and Ni/C composite made by hydrothermal carbonization using cellulose as raw material. The conclusion is as follows:(1) In the experiment of carbon material preparation using cellulose by hydrothermal carbonization, the best reaction temperature and reaction time respectively are300℃and12h. The carbon material are composed of flake, block and uniform carbon spheres which have size of about5-7μm and with good dispersibility. The carbon materials were amorphous.(2) We obtained Ni/C composite materials by one step using cellulose as carbon source, nickel metal elemental as source of composites. The composite materials were like-spherical with size uniformity and good dispersibility and their size were about1μm. In the composite materials, C were amorphous, while Ni were in elemental form.(3)There were kinds of oxygen functional groups in the surface of carbon materials and Ni/C composite, such as hydroxyl (-OH), carboxyl (-COOH) and carbonyl (-C=O), the presence of these functional groups provided a basis for material modification.(4)Both hydrothermal carbonization products and Ni/C composite materials had better thermal stability. Electrochemical performance test results show that specific capacitance of Ni/C composites have been significantly improved, compared with hydrothermal carbonization products, and the cycle stability of composite materials were relatively good. It is possible for the Ni/C composites to be applied to the super capacitor.