The so-called graphene powder is actually a graphene mixture with a single graphene layer. At present, the public has some confusion about graphene. Some enterprises or media reported that graphene can only be graphite.
Graphene has no clear definition in the world. According to the data, the original graphene only refers to a new material with a single-layer sheet structure composed of carbon, a two-dimensional material with a hexagonal honeycomb lattice plane film composed of carbon sp2 hybrid orbital groups, and the 20 1 1 Nobel Prize in Physics. The study of graphene refers to materials. Further research shows that two, three or even ten layers of carbon have their own special physical properties. At present, 10 layer is gradually recognized by the technical community, and 65438+ is recognized by the Standardization Committee of Graphene Alliance.
2. Graphene transparent film
The graphene transparent film uses methane or its gas copper foil. The so-called vapor deposition of graphene is more related to graphite resources. Graphene thin films are actually produced by a series of gas treatments, which make the metal substrate transparent until the metal substrate is full. Graphene itself is not attached to the metal substrate, and the color of graphene is only slightly different. The size of graphene is basically determined by the size of graphene film on metal substrate. Discussion on the Commercial Environment of Graphene Thin Films; The comprehensive economy is the key factor; Although this raw material ignores the production and transfer of graphene, generally speaking, every process is carried out in a dusty environment.
3. Graphene slurry
The application of graphene paste is the same as the conductive additive of vacuum display screen, lithium ion battery and other electrical appliances. Glass powder with graphene bonding at high temperature is sprinkled on the machine carrier, and the slurry is made into rolling slurry, which is directly sold to tour enterprises for preparing display screens, lithium-ion batteries and so on.
Generally speaking, there are three main types of mass production of graphene at present: one is to deposit graphene thin film materials with high metal surface ratio by chemical vapor deposition; This kind of graphite looks like fine black powder by physical or crushing graphene powder; Adding powder to prepare graphene conductive paste is convenient for enterprises to carry out deep processing. Preparation of graphene: graphene film graphene powder graphene paste is the sixth element between the former National 2D Carbon Technology Co., Ltd., Gefei Electric Representative and Ningbo Moxi Representative; The representative of Zheze Wanxin Graphite Valley Technology Co., Ltd. compiled a specific application example of graphene solution.
Detailed explanation of graphene transparent conductive film;
On June 3rd, 2065438, Deyang City, Sichuan Graphene Industry Technology Innovation Alliance, announced that the graphene transparent conductive film has entered the trial production stage for a long time, and the thickness of the graphene transparent conductive film is full of millimeters, which is widely used in mobile phone touch screens, smart phone soft screens and flexible LCD panels.
In fact, the application of conductive film leads the world. In June, 2065438+065438+,Samsung announced that it would jointly produce 30-inch graphene sheets (the corner line is about 76cm) with the Korean Army Museum. The production of giant graphene sheets is similar to that used in Novoselos. Mechanical stripping tape, first mechanical stripping tape (using transparent tape for the first time), graphite release tape, graphene transfer tape, etc. It is made of copper by roll CVD.
The reel transfer steps mainly include:
1. Polymer film bonded with copper foil graphene film;
2, chemically etching the copper foil;
3. The former technology of transferring graphene film to the target substrate has successfully applied for an international patent, which is mainly applied to the transparent conductive electrode of Samsung touch screen.
In addition to transfer, metal substrate CVD graphene transfers and dissolves PMMA, and metal PMMA is removed to prepare high-quality graphene films. The actual production reduces the complete phenomenon of graphene film transfer process. Before dissolving PMMA with acetone, a small amount of PMMA solution is added dropwise to dissolve PMMA, which is beneficial to reduce the force between graphene and PMMA, enhance the contact between graphene and the target substrate, and ensure the integrity of graphene film. In addition, the graphene film of Cu sheet is transferred by PMMA, and the metal copper is transferred by ferric chloride. The surface of the substrate was dissolved with acetone to remove PMMA, and the graphene film substrate was immersed in concentrated nitric acid-doped P-doped transparent conductive film. Because of its superior performance, this product is more expensive than transparent conductive film and is suitable for high-end fields.
Graphene transparent conductive film is mainly used for solar cell display devices and other surfaces.
The specific surface area is wide, and the degree of high transmittance increases. The solar radiation in the excitation region improves the sensitivity of the high-energy spectral region of the battery, and also serves as an antireflection layer in the excitation region to improve the transmittance. In addition, due to the high hole transport of graphene, functional layers are applied to solar cells, and graphene thin film dyes are applied to photovoltaic cells. As the rapid development of battery electrodes, graphene films have generally replaced the traditional oxide conductive films (indium oxide is more than tin oxide). Schematic diagram of graphene solar cell structure.
(According to: Ag-BCP-Cu-CuPc-pedot:PSS- graphene-quantum substrate, its graphene replaced the previous ITO film)
Flat panel display At present, graphene transparent conductive film is used in electric meters, communication equipment of game machines, test instruments and office automation equipment, portable computers, electric notebooks, video recorders, wall-mounted televisions and so on. Because of its ultra-thin, high transmittance, cheap raw materials and stable performance, it is favored by researchers.
(layer 1-8: glass-graphene -Cr/Au layer-polyvinyl alcohol-liquid crystal-alignment layer -ITO- glass)
Using optical microscope, a high-resolution liquid crystal display device was prepared by filling liquid crystal between graphene film prepared on Raman glass substrate and ITO interlayer with chrome-plated gold window on the other edge.
Graphene conductive paste
The graphite ore in Jixi was first processed into high purity graphite raw materials and then transported to the north bank of Songhua River in Harbin, 500 kilometers away. The production line of Harbin Wanxin Graphite Valley Technology Co., Ltd. has experienced a set of world-class complex processes. After baptism, Lu Xing has undergone earth-shaking changes. Ordinary graphite raw materials have ultra-high conductivity graphene products. Mainstream lithium battery manufacturers at home and abroad have decided to adopt Ice City graphene products. Several tons of graphene products have been transported in Harbin for a long time. At present, the main conductive adhesive shape lines of lithium battery enterprises are convenient for tourists to use directly.
The essence of graphene conductive paste is the combination of graphene and polymer, that is, the application of graphene conductive additive graphene lithium-ion battery mainly includes:
1. application of graphene lithium-ion battery: graphene is directly used as the negative electrode of lithium-ion battery to realize graphene transparent conductive film; The application of graphene/tin dioxide composite or graphene/silicon composite as the cathode of lithium ion battery mainly involves the application of graphene powder.
2. Application of graphene lithium-ion battery: Graphene, lithium ferrous phosphate and lithium vanadium phosphate are compounded to make electrode graphene powder for swimming application.
3. Graphene is used as a conductor additive for lithium batteries, so graphene paste is used.
Adding graphene conductive paste into lithium-ion batteries greatly improves the current charging and discharging performance, cycle stability and safety of lithium batteries, even exceeding the current high-performance lithium batteries. Carbon nanotube conductive additive needles are mixed with polymer matrix, and graphene slurry is used to prepare the main solution, and the molten mixture is polymerized in situ, so the industrialization degree is low.