What are the synthesis methods of conductive agents for lithium ion batteries?

Synthesis of Conductive Agents

Micromechanical Peeling Method

In 2004, Geim et al. successfully peeled monolayer graphene from high orientated pyrolytic graphite by micromechanical peeling method for the first time. Geim's team successfully prepared quasi-two-dimensional graphene using this method and observed its morphology, revealing the reason for the existence of two-dimensional crystal structure of graphene. High quality graphene can be prepared by micromechanical stripping method, but there are some shortcomings such as low yield and high cost, which can not meet the requirements of industrialization and large-scale production. At present, it can only be prepared on a small scale in laboratory.

chemical vapor deposition method

Chemical vapor deposition method (Chemical Vapor Deposition, CVD) on the problem of large-scale preparation of graphene for the first time had the new breakthrough.CVD method is refers to the material in the gas phase reaction conditions are issued by biochemical reaction, generate solids deposition on the surface of the solid substrate that heating, which made of solid material technology. At the Massachusetts institute of technology of Hong Kong, sung kyun kwan university and pursue university, such as Chen in graphene prepared by CVD method, etc. They use is a kind of based on nickel substrate simple tubular sedimentation furnace, carbon gas is piped in, such as hydrocarbons, it is decomposed into carbon deposition at high temperatures on the surface of nickel, the formation of graphene, by chemical etching, slightly make graphene films and nickel piece of graphene films were isolated. The film conductivity when the light transmittance of 80% 1.1 x 106 s/m, as an alternative to the potential of transparent conductive films. Can be prepared by CVD method of large area high quality graphene, but the ideal substrate material of single crystal nickel price is too expensive, this may be the important factors influencing the graphene industrialized production.CVD method can meet the requirements of large-scale preparation of high quality graphene, but the high cost, complicated process.

oxidation - reduction method

Oxidation - reduction process, low cost and easy to implement the best methods of preparation of graphene, preparation stable graphene suspension, and can solve the problem of graphene is not easy to disperse. Oxidation - reduction method refers to the natural graphite react with strong acid and strong oxidizing substances generated graphite oxide (GO), after ultrasonic dispersion preparation as graphene oxide (monolayer graphite oxide), add reducing agent to remove oxygen containing groups on the surface of the graphite oxide, such as carboxyl, epoxy and hydroxyl, graphene.

After the oxidation - reduction method is put forward, with its simple preparation of graphene laboratory technology become the most simple method, get the favor of the masses of graphene researchers. Ru off found by adding chemicals such as such as dimethyl hydrazine, hydroquinone, sodium boro hydride (NaBH4) and liquid hydrazine removal of graphene oxide oxygen-containing groups, such as can get graphene. Oxidation - reduction method to the preparation of stable graphene suspension, solve the problems in the graphene is difficult to disperse in the solvent.

Oxidation - reduction method shortcoming is easy to bring waste liquid pollution of macro preparation and preparation of graphene has certain defects, for example, $5, 7 Yuan, such as topological defects or defects - the structure of the OH groups, these will cause the graphene part of the loss of electrical performance, limit the application of graphene.

solvent stripping method

The principle of solvent stripping method is spread a small amount of graphite in solvent, form a low concentration of dispersion, use the function of ultrasonic destruction of graphite interlayer van der Waals force, the solvent can be inserted into graphite layers, stripping layer by layer, the preparation of graphene. This method will not damage like oxidation - reduction method of graphene structure, high quality graphene can be prepared. In n methyl pyrrolidone graphene has the highest yield (about 8%), the electrical conductivity of 6500 s/m. The study found that high directional thermal cracking thermal expansion graphite and microcrystalline graphite, artificial graphite stripping of graphene prepared by suitable for use in a solvent. Solvent stripping method to prepare high quality graphene, the whole process of liquid phase stripping without any defects, introduced on the surface of graphene, as in the areas such as microelectronics, multifunctional composite materials application provides a broad application prospect. The disadvantage is that production rate is very low.

solvent hot method

Solvent hot method refers to the special airtight reactor (autoclave), using organic solvent as reaction medium, by reaction system (or close to critical temperature) heated to a critical temperature, itself produces high pressure in the reaction system and an effective method for material preparation.

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