TW201406997A - A novel device which can continuously produce graphene flakes by electrochemical method - Google Patents

Abstract

This invention is a device designed for continuous production of graphene flakes by electrochemical method. The device consists of an electrochemistry unit which generates graphene flakes by electrochemical exfoliation; a filtration unit which separates graphene flakes from electrolyte solution; a guiding path which connects to the electrochemistry unit and transports the graphene flakes and electrolyte solution into the filtration unit; a grading collection unit which accepts the separated graphene flakes from the filration unit and separates these flakes by size. By the means, a device which produces graphene flakes continuously and electromchemically, the aim for fast and large scaled production of high quality graphene flakes is achieved.

Description

Device for producing graphene by continuous electrochemical method

This invention relates to a device for producing graphene, and more particularly to a device for producing graphene by a continuous electrochemical process.

In 2004, Professor AKGeim of the University of Manchester in the United Kingdom glued graphite sheets to a piece of tape and glued the other side of the graphite sheet with another piece of tape. When the two pieces of tape were torn apart, the graphite was peeled off into two thinner pieces. The graphite flakes are further adhered to the tape and then peeled off, and the tape peeling step is repeated several times to obtain a small piece of single-layer atomic thickness graphene. Graphene was observed by a transmission electron microscope to show that the carbon atoms in the graphene film were aligned in a high order.

Graphene has many excellent properties, such as high mechanical strength (~1,100GPa), the film is strong and brittle, but it can be tortuous; the gas cannot penetrate the graphene film; the thermal conductivity is up to 5300 W/m‧K, the carbon nanotubes and The diamond is good. At room temperature, the electron mobility of graphene exceeds 15000 cm2/V‧s, which is higher than the carbon nanotube (about 10000 cm2/V‧s), and it is twin (1400 cm2). /V‧s) is more than 10 times; its resistance is about 10-6 Ω‧cm, which is lower than copper or silver metal.

At present, there are about four methods for preparing graphene: (1) preparing graphene from a graphite material by mechanical stripping, which can easily and quickly obtain single-layer or multi-layer graphene, but can only be manufactured in a small amount; Chemical vapor deposition Method or epitaxial growth method for preparing graphene, using a hydrocarbon gas source that is passed through a pyrolysis and depositing on a nickel sheet or a copper sheet, which is characterized in that a large-area single-layer or multi-layer graphene can be prepared, but the disadvantage is uniform (3) Growth of graphene on an insulator substrate, for example, growth of extremely thin graphene on the surface of tantalum carbide, which is disadvantageous in that it is expensive and difficult to prepare a large area; (4) using an organic acidic solvent Graphene oxide (GO) is prepared by intercalation, and graphene is obtained through a reduction procedure. The disadvantage is that the treatment time is long, and the graphene after reduction is easily deformed and warped, so that the quality of graphene is uneven.

In addition, the use of electrochemical means, at room temperature, the change of the transmission voltage, the production of graphene sheets can be completed, which is characterized by the fact that the high-temperature reduction step is not required, so that the process can be simplified and the large-sized graphene sheets can be easily obtained. Production.

As described above, the method for producing graphene by electrochemical method has the advantages of simple process, high speed, high quality, and large area. Therefore, there is a great need in the industry for a continuous automated electrochemical method for stripping graphite electrodes out of graphene. The sheet production method and device can reduce the manual working time and can produce graphene sheets in large quantities. Therefore, the present invention proposes a device for producing graphene by continuous electrochemical method, so that the cost and the aging can be simultaneously achieved. There is no need for a high-temperature reduction process, and the purpose of obtaining high-quality graphene sheets can be achieved quickly and in large quantities.

In view of the above disadvantages of the prior art, the main purpose of the present invention is to provide A device for producing graphene by a continuous electrochemical method, integrating an electrochemical unit, a filter unit, a drain, and a fractionation unit to prepare high-quality graphene sheets.

In order to achieve the above object, according to one aspect of the present invention, an apparatus for producing graphene by a continuous electrochemical method is provided, which comprises: an electrochemical unit which is electrochemically stripped of graphene sheets; and a filtration unit The method is for separating the graphene sheet and the electrolyte; a drain channel connecting the electrochemical unit for conveying the graphene sheet and the electrolyte to the filtering unit; and a stepping collecting unit, receiving the filtering unit and separating A graphene sheet for separating graphene sheets of different sizes.

The electrochemical unit comprises a positive and negative timing switching DC power source, an auxiliary heating device, an electrolytic cell and a graphite electrode group, wherein the positive and negative timing switching DC power source is connected to the graphite electrode group, and the graphite electrode group is arranged to be set in the electrolysis The electrolyte in the tank reacts electrochemically. The graphite electrode assembly is composed of at least two or more even graphite electrodes, and comprises a half of a graphite electrode used as an anode and a half of a graphite electrode used as a cathode. The graphite electrode may be selected from natural graphite, high crystalline graphite, and coke. It is one of artificial graphite, mesophase pitch artificial graphite, polymer artificial graphite, carbon fiber, graphite fiber, carbon/carbon composite material, etc., and the potential relationship between the graphite electrodes and the polar electrodes can be connected in parallel. Spatially interlaced, spaced apart by a graphite electrode of opposite polarity to form an array of combinations, and then positively or negatively, respectively, using an electrochemical reaction with appropriate electricity The solution can be used to produce graphene sheets. In addition, the graphite electrodes can be connected in series to form two sets of graphite electrodes, and then positive and negative, respectively, and an electrochemical equilibrium reaction can occur between the positive and negative graphite electrodes. The positive and negative timing timing switching DC power source is connected with the graphite electrode for positive and negative electricity connection with the graphite electrode group for electrochemical reaction, and at the same time, the electrode conversion can be completed by controlling the time, and the electrode in the graphite electrode group is electrically converted to promote electrochemistry. The auxiliary heating device uses a microwave, ultrasonic, and non-contact heating device to heat the entire electrochemical unit to increase the graphene production efficiency.

An electrolyte preparation tank may be disposed beside the electrochemical unit, and the electrolyte preparation tank is disposed on one side of the electrolytic tank, and the bottom position of the electrolyte preparation tank is higher than the electrolyte liquid level in the electrolytic tank. In addition, an electrolyte monitoring device may be disposed, the electrolyte monitoring device includes a pH detector and an electrolyte level monitoring device, and when detecting that the pH value of the electrolyte in the electrolytic cell does not meet the set value or the electrolyte solution When the surface monitoring device detects that the height of the electrolyte does not reach a certain set value, the electrolyte mixing tank can send the prepared electrolyte into the electrolytic bath.

a draining channel, one end of which is connected to the electrochemical unit, and the other outlet end is disposed above the filtering unit, the two ends of the guiding channel are not horizontal, and have an oblique angle, when the electrochemical unit produces the graphene sheet, The graphene flakes will float on the electrolyte; the function of the drain channel is to transport the electrolyte and the graphene flakes, and the electrolyte flowing out of the liquid and the graphene flakes can be transported to the filter unit by the oblique angle.

The filter unit comprises a rotary filter belt and an electrolyte recovery tank, The rotary filter belt is a mesh structure, and the width of the rotary filter belt is larger than the outlet end of the drainage channel. When the drainage channel transports the electrolyte and the graphene sheet to the rotary filter belt, the network structure meshes the graphene. The sheet is passed, and the electrolyte flows down to the electrolyte recovery tank to complete the filtration and separation of the electrolyte and the graphene sheets.

The rotary filter belt is a rotary filter belt having a vertical direction, and the graphene sheet on the rotary filter belt can be dropped by gravity, so that the grading collecting unit can receive the graphene sheet separated by the filtering unit, so The grading collecting unit may be disposed under the rotary filter belt, and the structure is a plurality of screens including a mesh structure, each screen has a different mesh structure, and a screen vibration device is disposed, and the main purpose is to utilize The screen vibrating device is used for vibrating the screen, so that the graphene sheets can separate graphene sheets of different sizes due to vibration and different mesh structures, thereby completing the grading operation of the graphene sheets.

In the above device, a deionized water storage tank may be disposed beside the electrochemical unit, containing deionized water, the purpose of which is to spray the deionized water on the rotary filter belt, and use the deionized water to help the graphene sheet to leave the rotation. The filter belt falls into the grading collection unit.

The above summary, the following detailed description and the accompanying drawings are intended to further illustrate the manner, the Other objects and advantages of the present invention will be described in the following description and drawings.

The embodiments of the present invention are described below by way of specific examples, and those skilled in the art can readily appreciate other advantages and functions of the present invention from the disclosure herein.

The invention mainly utilizes an electrochemical method to peel off the graphite electrode and suspend the graphene sheet on the liquid surface of the electrolyte, and then continuously inject the electrolyte into the electrolytic cell through the electrolyte mixing tank, so that the liquid surface rises and overflows the tank body, thereby causing the electrolyte. Flow into the electrolyte drain. The graphene flakes are sprayed to the continuous rotary filter belt with the electrolyte, and adhere to the surface of the rotary filter belt, and the graphene sheets adhered to the surface of the rotary filter belt are washed by spraying the deionized water from the inside to the outside. To the grading collection unit, the graphene sheets are collected by screen meshing, and the electrolyte is washed away. And the use of the acid pH detector and the electrolyte liquid level monitoring device to facilitate timely replenishment of the electrolyte to maintain continuous operation of the system.

Please refer to the first figure for a schematic diagram of a device for producing graphene by continuous electrochemical method. As shown in the figure, the present invention provides a continuous electrochemical method for producing graphene, comprising: an electrochemical unit which is electrochemically stripped of graphene sheets, comprising a positive and negative timing switching DC power source 111, a An auxiliary heating device 112, an electrolytic cell 113 and at least one graphite electrode group 114; a filtering unit for separating the graphene sheet and the electrolyte 110, comprising a rotary filter belt 131 and an electrolyte recovery tank 132; a draining channel connecting the electrochemical unit for transporting graphene sheets and electrolysis The liquid is supplied to the filtering unit 130; a grading collecting unit 140 receives the graphene sheets separated by the filtering unit for separating graphene sheets of different sizes.

Please refer to the second figure for a top view of a device for producing graphene by continuous electrochemical method. As shown in the figure, the electrochemical method of the present invention comprises a positive and negative timing switching DC power supply 211, which has the function of supplying a fixed current and automatically switching the polarity direction at intervals of a period of time; the positive and negative timing switching DC power supply 211 is connected to the graphite electrode assembly. 214, a graphite electrode group 214 DC power supply is provided, the graphite electrode group 214 includes at least two graphite electrodes, one is a graphite electrode used as an anode (positively charged), and the other is a graphite electrode used as a cathode (negatively charged), but Without limitation, a graphite electrode of a plurality of anodes and a graphite electrode of a plurality of cathodes may be included. The potential relationship between the electrodes of the same polarity is connected in parallel, and is staggered in space with each other, and a graphite electrode of opposite polarity is interposed therebetween. A combination of array forms. In this embodiment, the graphite electrode assembly 214 is implemented in a parallel manner to perform an electrochemical method, which is disposed in an electrolytic cell 213. The electrolyte 110 is placed in the electrolytic cell 213, and the electrolyte component may include a sulfuric acid component or potassium hydroxide. The composition, when the graphite electrode group 214 is energized, the graphene sheet will appear and float in the electrolyte after electrochemical intercalation, exfoliation, and the like. An auxiliary heating system is further disposed in the electrolytic cell 213. For example, it may be a microwave, ultrasonic or non-contact heating device. The auxiliary heating system has two main functions, one of which is to provide thermal energy of the graphite electrode and the electrolyte to accelerate the electrification. Learning anti The second is to maintain the system constant temperature, in order to ensure the stability of the graphene product.

The invention comprises a drainage channel 220, one end of which is connected to the electrolytic cell 213, and the other end of the outlet is located above the filtering unit. The two ends of the drainage channel 220 are not horizontal, have an inclined angle, and are connected to one end of the electrolytic cell 213. Higher, when the graphene sheets are produced, the electrolyte and the graphene sheets are transported to the filter unit by the drain channel 220, and the drain channel 220 and the filter unit can be directly connected to the filter unit or as shown in this embodiment. The outlet end of the drain channel 220 is of an open design, and the electrolyte 110 and the graphene sheet are transported by gravity to the filter unit. In this embodiment, the filter unit is disposed under the drain channel 220, and the width of the drain channel 220 is smaller than that of the drain channel 220. The outlet end has a large width to facilitate the acceptance of the electrolyte and the graphene sheets. When the electrolyte 110 and the graphene sheets pass through the filter unit, the graphene sheets are supported by the rotary filter belt 231 having a mesh structure, and electrolysis The liquid then falls into the electrolyte recovery tank 232, so that the separation of the graphene sheets from the electrolyte is completed.

In the above process, the liquid level of the electrolyte 110 in the electrolytic cell 213 must be higher than that of the drain channel 220, so that the electrolyte and the graphene sheet can be transported to the filter unit through the drain channel 220, and therefore, the electrolyte in the electrolytic cell 213 The liquid level must be maintained at a fixed height. In this embodiment, the electrolyte that has fallen into the electrolyte recovery tank 232 is transported through the pipe 262 to the electrolyte preparation tank 250. After proper preparation, the electrolyte is replenished to the electrolytic tank. In 213, the liquid level of the electrolyte in the electrolytic cell 213 can be maintained. In addition, you can use the pH detector and electrolyte level monitoring The device monitors the electrolyte condition at any time to replenish the electrolyte 110.

The moving direction of the rotary filter belt 131 includes a horizontal moving direction and a vertical moving direction. When the graphene flakes fall on the rotary filter belt 131, the graphene flakes are above the rotary filter belt 131 and perform a horizontal direction. Movement, at this time, the graphene flakes are separated from the electrolyte; when the graphene flakes move vertically in the rotary filter belt 131, a portion of the graphene flakes will fall into the grading collection unit due to gravity factors. 140, other graphene sheets are still on the rotary filter belt 131; when the rotary filter belt 131 is further moved in the horizontal direction, at this time, the graphene sheets are below the rotary filter belt 131, which can be further used in this embodiment. The deionized water is sprayed by the showerhead 163, and the force of the water column and gravity is utilized to cause the graphene sheets to fall into the hierarchical collection unit 140.

The grading collecting unit is disposed under the rotary filter belt, and comprises a plurality of mesh 141 of mesh structure, each mesh 141 comprises different mesh structures, for example, mesh mesh 141 of different sizes can be disposed, and the larger the mesh Set at the top, the smaller the mesh is set below, so that the separation of the graphene sheets of different sizes can be completed by screening the screens 141 of different sizes, and at the same time, by a screen vibrating device 142 Vibration of the screen 141 will increase the separation efficiency of graphene sheets of different sizes.

The above-described embodiments are merely illustrative of the features and functions of the present invention, and are not intended to limit the scope of the technical scope of the present invention. Modifications and variations of the above-described embodiments can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention The scope shall be as listed in the scope of application for patents mentioned later.

110‧‧‧ electrolyte

111, 211‧‧‧ Positive and negative timing switching DC power supply

112‧‧‧Auxiliary heating device

113, 213‧‧‧ Electrolyzer

114, 214‧‧‧ graphite electrode set

120, 220‧‧‧drain

131, 231‧‧‧ Rotary filter belt

132, 232‧‧ ‧ electrolyte recovery tank

140‧‧‧Class collection unit

141‧‧‧ screen

142‧‧‧ Screen shaker

150, 250‧‧‧ electrolyte mixing tank

160‧‧‧Deionized water storage tank

161, 162, 262‧ ‧ pipes

163, 251‧‧ ‧ sprinkler head

171‧‧‧Flow control valve

172‧‧‧Liquid pump

The first figure is a schematic diagram of a device for producing graphene by a continuous electrochemical method according to the present invention; the second figure is a top view of a device for producing graphene by a continuous electrochemical method according to the present invention.

110‧‧‧ electrolyte

111‧‧‧ Positive and negative timing switching DC power supply

112‧‧‧Auxiliary heating device

113‧‧‧electrolyzer

114‧‧‧Graphite electrode set

120‧‧‧Drainage channel

131‧‧‧Rotary filter belt

132‧‧‧ electrolyte recovery tank

140‧‧‧Class collection unit

141‧‧‧ screen

142‧‧‧ Screen shaker

150‧‧‧Electrolyte mixing tank

160‧‧‧Deionized water storage tank

161, 162‧‧‧ pipeline

163‧‧‧ sprinkler head

171‧‧‧Flow control valve

172‧‧‧Liquid pump

Claims (16)

A continuous electrochemical method for producing graphene comprises: an electrochemical unit for separating a graphene sheet by electrochemical method; a filtering unit for separating a graphene sheet and an electrolyte; and a drain channel Connecting the electrochemical unit to transport the graphene sheet and the electrolyte to the filtering unit; a grading collecting unit receiving the graphene sheet separated by the filtering unit for separating graphene sheets of different sizes . The apparatus for producing graphene by a continuous electrochemical method according to claim 1, wherein the electrochemical unit comprises a positive and negative timing switching DC power source, an auxiliary heating device, an electrolytic cell and a graphite electrode group. . The apparatus for producing graphene by a continuous electrochemical method according to claim 2, wherein the graphite electrode group comprises a graphite electrode for positive electric power and a graphite electrode for negative electric power. The apparatus for producing graphene by a continuous electrochemical method as described in claim 3, wherein the graphite electrode is selected from the group consisting of natural graphite, high crystalline graphite, coke-based artificial graphite, mesophase pitch artificial graphite, Polymer is one of artificial graphite, carbon fiber, graphite fiber and carbon/carbon composite material. A device for producing graphene by a continuous electrochemical method as described in claim 3, wherein the graphite electrodes are arranged in series or in parallel. The device for producing graphene by the continuous electrochemical method as described in claim 2, further comprising an electrolyte preparation tank, wherein the electrolyte preparation tank is disposed on one side of the electrolytic tank, and the electrolyte is adjusted to the bottom of the tank. The position is higher than the electrolyte level in the electrolytic cell. The apparatus for producing graphene by a continuous electrochemical method as described in claim 2, wherein the auxiliary heating device is one selected from the group consisting of microwave, ultrasonic, and non-contact heating devices. The apparatus for producing graphene by the continuous electrochemical method as described in claim 2, further comprising an electrolyte monitoring device, wherein the electrolyte monitoring device comprises a pH detector and an electrolyte level monitoring device. . The device for producing graphene by the continuous electrochemical method according to claim 1, wherein the drainage prop includes an outlet end disposed on the filter unit at an oblique angle. The apparatus for producing graphene by a continuous electrochemical method according to claim 1, wherein the filtering unit comprises a rotary filter belt and an electrolyte recovery tank. A device for producing graphene by a continuous electrochemical method as described in claim 10, wherein the width of the rotary filter belt is greater than the width of the outlet end. The apparatus for producing graphene by a continuous electrochemical method according to claim 10, wherein the rotary filter belt comprises a mesh structure. The apparatus for producing graphene by a continuous electrochemical method as described in claim 1, wherein the hierarchical collection unit is disposed in the rotary filter Below the belt, it consists of a plurality of screens of mesh structure, each screen having a different network structure. The apparatus for producing graphene by the continuous electrochemical method as described in claim 13 further comprises a screen vibrating device, wherein the screen vibrating device is for vibrating the screen. The apparatus for producing graphene by the continuous electrochemical method according to claim 1, further comprising a sprinkler head, wherein the sprinkler head is used to spray deionized water to the rotary filter belt. The apparatus for producing graphene by the continuous electrochemical method according to claim 1, further comprising a deionized water storage tank, wherein the deionized water storage tank is disposed on one side of the electrolytic tank.