A method for large-scale preparation of graphene

Abstract

The invention discloses a method for preparing graphene on a large scale. The method comprises the following steps: a, adding graphite intercalation compound powder into compound expanding liquid, and performing expansion reaction to obtain an expanded vermicular graphene aggregate suspension; b, filtering the vermicular graphene aggregate suspension to obtain a vermicular graphene aggregate; c, washing the vermicular graphene aggregate by using a metal ion complexing agent and water sequentially to obtain a vermicular graphene aggregate wet material with the PH value of 6-8; d, adding the vermicular graphene aggregate wet material washed by water into a compound stripping liquid, and performing ultrasonic oscillation for 0.5-20 hours so as to disperse graphene into the compound stripping liquid to form a graphene solution; e, removing water from the graphene solution by a flash drying or freeze drying method to obtain graphene powder. After adoption of the method, a high-quality graphene product with the single batch production being up to hundreds of kilograms can be obtained.

Description

technical field [0001] The invention relates to the field of graphene, in particular to a method for large-scale preparation of graphene, which can produce hundreds of kilograms of high-quality graphene products in a single batch. Background technique [0002] Since its discovery in 2004, graphene has attracted much attention as a new type of carbon material. It is a completely sp 2 The quasi-two-dimensional crystal material composed of hybrid carbon atoms with a thickness of only one atomic layer or several single atomic layers has excellent properties such as high light transmission and electrical conductivity, high specific surface area, high strength and flexibility, etc. It is expected to be widely used in the fields of high-performance nanoelectronic devices, optoelectronic devices, gas sensors, composite materials, field emission materials and energy storage. However, the low-cost and large-scale preparation of high-quality graphene still faces difficulties, which ...

AI Technical Summary

Problems solved by technology

[0005] First, the above-mentioned patent mainly utilizes metal ions (M x+ ) catalyzes the decomposition of hydrogen peroxide in the interlayer to produce oxygen (O 2 ) exfoliation of graphite to obtain graphene. At the beginning of the expansion reaction, metal ions only exist between the graphite layers, and the reaction is mainly based on effective decomposition; as the reaction proceeds, the interlayer metal ions gradually dissolve into the liquid phase. When the concentration of metal ions increases to a certain level, it will cause intensified ineffective decomposition, especially in the case of large-scale preparation (single-batch preparation of hundreds of kilograms of graphene), the increase in the amount of material will lead to the dissolution from the graphite layer The amount of metal ions is huge. Conversely, the increase of materials also hinders the diffusion of metal ions in the solution. However, since the expansion liquid in the above patent is oxalic acid or hydrogen peroxide solution, the expansion liquid cannot treat the metal ions in the solution. It leads to the intensification of local invalid decomposition, which reduces the amount of effective substances participating in the expansion reaction, resulting in insufficient expansion of intercalated graphite raw materials, which adversely affects the expansion of graphite, so that high-quality graphene cannot be obtained on a large scale

Second, it is difficult to completely remove the intercalation agent after stripping, resulting in too high impurity content (5-10 wt%) in the resulting graphene product, which will adversely affect subsequent applications

Third, most of the obtained graphene layers are concentrated in 7-9 layers, and the quality and performance of graphene products are poor

Fourth, ultrasonic stripping requires a large amount of organic solvents or aqueous or organic solutions of various surfactants, resulting in higher production costs for graphene

Fifth, when graphite is exfoliated into graphene, the specific surface area increases sharply. At the same time, due to the weak oxidation in the expansion reaction, the surface of graphene is negatively charged, so it is easy to adsorb intercalants and positively charged metal ions in the solution. , due to the increase in the amount of processed materials during mass production, these metal ions are difficult to remove by simple water washing, thus resulting in an increase in the content of metal ions in the resulting graphene products

The presence of a large number of metal ions will adversely affect the application of graphene

Although pickling can effectively remove metal ions, a large amount of pickling will increase the cost and cause serious environmental pollution.

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