Method for preparing flow battery electrode from biomass textile fabric

Abstract

The invention provides a method for preparing a flow battery electrode from a biomass textile fabric, and belongs to the field of activated carbon fiber preparation, the preparation method comprises the following steps: carrying out ultrasonic impregnation on a cellulose textile fabric in a phosphoric acid solution with a certain concentration and under a certain power for a period of time, and drying at a certain temperature after impregnation is completed; activating the activated carbon fiber cloth subjected to phosphoric acid dipping treatment for a certain time at a certain temperature under the protection of nitrogen; the prepared activated carbon fiber is gradually placed in a diluted hydrochloric acid solvent and an aqueous solution to be cleaned and dried, and a target product is obtained. According to the preparation method, the cellulose fiber textile cloth is used as a precursor, so that the production cost can be reduced, and the targets of high specific surface area, high pore volume, high mechanical self-supporting performance and low resistivity of the activated carbon fiber can be achieved at the same time.

Description

Technical Field

[0001] The invention belongs to the field of activated carbon fiber preparation and relates to a method for preparing flow battery electrodes using biomass textile cloth. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] In recent years, flow batteries have been widely used in large-scale energy storage due to their high safety, long cycle life, environmental friendliness, high energy efficiency, and independent design of power and capacity. Electrodes, as the site of electrochemical reactions in flow batteries, are one of the most important components that affect the performance of flow batteries.

[0004] Activated carbon fiber materials are widely used in the field of liquid flow batteries due to their advantages such as high specific surface area, easily controllable pore structure and surface chemical structure, and high pore volume. However, the preparation process of traditional activated carbon fibers (PAN-based, asphalt-based, viscose-based) mainly includes steps such as stabilization, high-temperature carbonization and activation. It has the disadvantages of expensive raw materials, complex process, high energy consumption, unsatisfactory specific surface area and pore volume, which greatly limits the application and promotion of activated carbon fiber materials in liquid flow batteries. For example: The paper "Preparation of viscose-based phosphorus-oxygen co-doped activated carbon fibers and their atmospheric pressure hydrogen storage performance" uses ultrasound-assisted phosphoric acid activation technology to prepare a viscose-based phosphorus-oxygen co-doped activated carbon fiber, but the carbon fiber prepared by this method has a small specific surface area and pore volume, which cannot meet the performance requirements as a liquid flow battery electrode.

[0005] At present, the mechanical self-supporting properties and porosity of porous carbon fibers are contradictory. Whether the stability of the porous carbon fiber matrix can be maintained after activation is the key to its application in flow batteries. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a high specific surface area P / O co-doped cellulose-based activated carbon fiber cloth for liquid flow batteries and its preparation method and application, which solves the problems of expensive raw materials, complex processes, high energy consumption, and unsatisfactory specific surface area and pore volume of activated carbon fiber electrode materials for liquid flow batteries in the prior art.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] The first aspect of the present invention provides a method for preparing a flow battery electrode from a biomass textile fabric, comprising:

[0009] The cellulose fibers are placed in a phosphoric acid solution for ultrasonic impregnation, and dried once to obtain an activator-loaded fiber cloth;

[0010] activating the fiber cloth loaded with the activator under the protection of an inert atmosphere to obtain porous carbon fibers;

[0011] The porous carbon fiber is acid-washed and water-washed, and then dried twice to obtain the porous carbon fiber.

[0012] The present invention has found that compared with precursors such as polyacrylonitrile, cellulose fiber cloth has relatively more hydroxyl groups, and dehydration at high temperature will produce water vapor, which can be used as a physical activator in combination with a chemical activator (phosphoric acid) to make the prepared porous carbon fiber have a higher specific surface area and pore volume. At the same time, compared with precursors such as polyacrylonitrile, which require additional processes such as pre-oxidation to maintain the stability of porous carbon fibers, cellulose fiber cloth is more suitable for a one-step phosphoric acid activation process, which is conducive to the large-scale production of porous carbon fibers.

[0013] In some embodiments, the mass concentration of the phosphoric acid solution is 0.1 wt%-60 wt%.

[0014] In some embodiments, the ultrasonic immersion time is 0.5-6 hours.

[0015] In some embodiments, the ultrasound power is 10W-100W.

[0016] In some embodiments, the primary drying temperature is 40°C-100°C.

[0017] In some embodiments, the activation temperature is 600° C.-900° C., and the activation time is 0.5 to 6 hours.

[0018] In some embodiments, the specific steps of acid washing and water washing are: ultrasonication in dilute hydrochloric acid and water at 80°C-85°C for 0.5-12h.

[0019] In some embodiments, the secondary drying is carried out at a temperature of 80° C.-85° C. for 20-24 hours.

[0020] The second aspect of the present invention provides a flow battery electrode prepared using the biomass textile fabric prepared by the above method.

[0021] Different from traditional batteries (such as lithium-ion batteries), the electrodes of redox flow batteries only serve as the site for the reaction of active substances, and do not undergo redox reactions themselves. Therefore, the flow battery electrodes of the present invention have high specific surface area and high pore volume, and have the following advantages:

[0022] 1. Improve the efficiency of electrochemical reactions: Porous carbon fibers have a high specific surface area, which increases the contact area between the electrode and the electrolyte, and helps to improve the efficiency of redox reactions.

[0023] 2. Improve the mass transfer process: The porous carbon fiber has a rich porous structure, which can effectively promote the reaction mass transfer process and help the substances in the electrolyte reach the electrode surface more effectively.

[0024] 3. Enhanced electrochemical performance: The porous carbon fibers exhibit excellent electrochemical performance due to their high specific surface area, large pore volume and high electrical conductivity.

[0025] The second aspect of the present invention provides the use of the above-mentioned biomass textile fabric in the preparation of liquid flow batteries.

[0026] Beneficial effects of the present invention

[0027] (1) The present invention uses cellulose fiber textile fabric as a precursor, which is green, environmentally friendly, widely available, and low in cost.

[0028] At the same time, the present invention adopts a one-step phosphoric acid activation, the preparation process is simple, and continuous production is easy to achieve. The performance of the prepared activated carbon fiber reaches or exceeds the current level of industrial production of activated carbon fiber.

[0029] (2) The cellulose-based activated carbon fibers prepared in the present invention have high specific surface area, high pore volume and low resistivity, and can be used as liquid flow battery electrodes.

[0030] (3) The preparation method of the present invention is simple, practical and easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention, and the exemplary embodiments of the present invention and their description are used to explain the present invention, and do not constitute improper limitations on the present invention.

[0032] Figure 1 is a scanning electron microscope image of a single activated carbon fiber prepared in Example 3 of the present invention;

[0033] Figure 2 is a scanning electron microscope image of the activated carbon fiber cloth prepared in Example 3 of the present invention;

[0034] Figure 3 This is a scanning electron microscope image of the porous carbon material prepared in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0035] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0036] The present invention will be further described in detail below in conjunction with specific embodiments. It should be noted that the specific embodiments are intended to explain the present invention rather than to limit it.

[0037] Example 1

[0038] This embodiment provides a method for preparing a high specific surface area activated carbon fiber cloth, comprising:

[0039] Step 1: The cellulose fiber cloth was ultrasonically immersed in a 30 wt % phosphoric acid solution for 2 h, and then dried at 80° C. after the immersion was completed.

[0040] Step 2: Activate the fiber cloth treated in step 1 at 700° C. for 2 h.

[0041] Step 3: The porous carbon fibers treated in step 2 were respectively placed in 1M dilute hydrochloric acid solution and deionized water for cleaning and dried at 80°C for 24 hours.

[0042] The specific surface area of ​​the prepared activated carbon fiber is 1056 m 2 / g, pore volume 0.584cm 3 / g, resistivity is 15.822Ω·cm, and tensile strength is 132.5Kpa.

[0043] Example 2

[0044] This embodiment provides a method for preparing a high specific surface area activated carbon fiber cloth, comprising:

[0045] Step 1: The cellulose fiber cloth was ultrasonically immersed in a 30 wt % phosphoric acid solution for 2 h, and then dried at 80° C. after the immersion was completed.

[0046] Step 2: Activate the fiber cloth treated in step 1 at 800° C. for 2 h.

[0047] Step 3: The porous carbon fibers treated in step 2 were respectively placed in 1M dilute hydrochloric acid solution and deionized water for cleaning and dried at 80°C for 24 hours.

[0048] The specific surface area of ​​the prepared activated carbon fiber is 1272 m 2 / g, pore volume is 0.664cm 3 / g, the resistivity is 6.016Ω·cm, and the tensile strength is 147.7Kpa.

[0049] This embodiment provides a method for preparing a high specific surface area activated carbon fiber cloth, comprising:

[0050] Step 1: The cellulose fiber cloth was ultrasonically immersed in a 30 wt % phosphoric acid solution for 2 h, and then dried at 80° C. after the immersion was completed.

[0051] Step 2: Activate the fiber cloth treated in step 1 at 900° C. for 2 h.

[0052] Step 3: The porous carbon fibers treated in step 2 were respectively placed in 1M dilute hydrochloric acid solution and deionized water for cleaning and dried at 80°C for 24 hours.

[0053] The specific surface area of ​​the prepared activated carbon fiber is 1727 m 2 / g, pore volume 1.18cm 3 / g, resistivity is 2.454Ω·cm, and tensile strength is 212.2Kpa.

[0054] Figure 1 This is a surface morphology picture of a single activated carbon fiber prepared in this example. It can be seen that the activated carbon fiber maintains a uniform fiber structure and some particle roughness is generated on the surface. Figure 2 This is the surface morphology of the activated carbon fiber cloth prepared in this example. It can be seen that after high-temperature activation with phosphoric acid, the activated carbon fiber cloth still maintains a good fiber weaving structure, which is beneficial to maintaining its mechanical self-supporting performance.

[0055] Comparative Example 1

[0056] The difference between this comparative example and Example 1 is that the activation temperature of this comparative example is lower, which is 600° C. The specific steps are as follows:

[0057] Step 1: The cellulose fiber cloth was ultrasonically immersed in a 30 wt % phosphoric acid solution for 2 h, and then dried at 80° C. after the immersion was completed.

[0058] Step 2: Activate the fiber cloth treated in step 1 at 600° C. for 2 h.

[0059] Step 3: The porous carbon fibers treated in step 2 were respectively placed in 1M dilute hydrochloric acid solution and deionized water for cleaning and dried at 80°C for 24 hours.

[0060] The specific surface area of ​​the prepared activated carbon fiber is 965.8 m 2 / g, pore volume 0.548cm 3 / g, resistivity is 22.796Ω·cm, and tensile strength is 120.4KPa. On the one hand, due to the low activation temperature, the activation etching effect of phosphoric acid on the fiber cloth is weak, resulting in a smaller specific surface area and pore volume than in Example 1. On the other hand, due to the low activation temperature, the graphite-like crystallites are imperfect, resulting in a lower conductivity.

[0061] Comparative Example 2

[0062] The difference between this comparative example and Example 1 is that the concentration of the phosphoric acid activator in this comparative example is higher, which is 60wt%. The specific steps are as follows:

[0063] Step 1: The cellulose fiber cloth was ultrasonically immersed in a 60 wt % phosphoric acid solution for 2 h, and then dried at 80° C. after the immersion was completed.

[0064] Step 2: Activate the fiber cloth treated in step 1 at 800° C. for 2 h.

[0065] Step 3: The porous carbon fibers treated in step 2 were respectively placed in 1M dilute hydrochloric acid solution and deionized water for cleaning and dried at 80°C for 24 hours.

[0066] Its specific surface area is 1704m 2 / g, pore volume 1.36cm 3 / g, has become particles and has no mechanical self-supporting properties. Figure 3 The surface morphology of the carbon paper prepared in this comparative example; Figure 3 It can be seen that the porous material prepared under this condition has completely lost its fiber morphology and turned into a porous carbon particle state, which is not conducive to the large-scale commercial application of self-supporting cellulose-based activated carbon fiber cloth.

[0067] Comparative Example 3

[0068] The difference between this comparative example and Example 1 is that the polyacrylonitrile-based fiber cloth is used in step 1 of this comparative example. The specific steps are as follows:

[0069] Step 1: ultrasonically immerse the polyacrylonitrile-based fiber cloth in a 30 wt % phosphoric acid solution for 2 h, and then dry it at 80° C. after immersion.

[0070] Step 2: Activate the fiber cloth treated in step 1 at 800° C. for 2 h.

[0071] Step 3: The porous carbon fibers treated in step 2 were respectively placed in 1M dilute hydrochloric acid solution and deionized water for cleaning and dried at 80°C for 24 hours.

[0072] The specific surface area of ​​the prepared activated carbon fiber is 859 m 2 / g, pore volume 0.63cm3 / g, has become a porous carbon particle, without mechanical self-supporting properties. It can be seen that the selection of precursors and the physical activation of water vapor play an important role in the specific surface area, pore volume and mechanical self-supporting properties of activated carbon fibers.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing flow battery electrodes from biomass textile fabrics, characterized in that: include: The cellulose fibers are placed in a phosphoric acid solution for ultrasonic impregnation, and dried once to obtain an activator-loaded fiber cloth; activating the fiber cloth loaded with the activator under the protection of an inert atmosphere to obtain porous carbon fibers; The porous carbon fiber is acid-washed and water-washed, and then dried twice to obtain the porous carbon fiber.

2. The method for preparing flow battery electrodes from biomass textile fabrics according to claim 1, characterized in that: The mass concentration of the phosphoric acid solution is 0.1wt%-60wt%.

3. The method for preparing flow battery electrodes from biomass textile fabrics according to claim 1, characterized in that: The ultrasonic immersion time is 0.5-6h.

4. The method for preparing flow battery electrodes from biomass textile fabrics according to claim 1, characterized in that: The ultrasonic power is 10W-100W.

5. The method for preparing flow battery electrodes from biomass textile fabrics according to claim 1, characterized in that: The primary drying temperature is 40°C-100°C.

6. The method for preparing flow battery electrodes from biomass textile fabrics according to claim 1, characterized in that: The activation temperature is 600° C.-900° C., and the activation time is 0.5-6 hours.

7. The method for preparing flow battery electrodes from biomass textile fabrics according to claim 1, characterized in that: The specific steps of the acid washing and water washing are: ultrasonicating in dilute hydrochloric acid and water at 80° C.-85° C. for 0.5-12 hours.

8. The method for preparing flow battery electrodes from biomass textile fabrics according to claim 1, characterized in that: The secondary drying temperature is 80°C-85°C for 20-24h.

9. Use the biomass textile fabric prepared by the method according to any one of claims 1 to 8 to prepare flow battery electrodes.

10. Use of the biomass textile fabric according to claim 9 in preparing a liquid flow battery device.

Images