A method for preparing flow battery electrodes by activating and carbonizing pre-oxidized fiber woven fabric

Abstract

The present invention provides a method for preparing liquid flow battery electrodes by activating and carbonizing pre-oxidized fiber woven fabrics, which belongs to the field of electrode material preparation, and includes: ultrasonically impregnating the pre-oxidized fiber woven fabrics in a phosphoric acid solution, drying once, and obtaining a pre-oxidized silk cloth loaded with an activator; carbonizing and activating the pre-oxidized silk cloth loaded with an activator under the protection of an inert atmosphere to obtain activated carbon fibers; washing the activated carbon fibers with water, drying them for a second time, and carbonizing them under an inert atmosphere to obtain activated carbon fiber woven fabrics. The present invention uses pre-oxidized fiber woven fabrics (including biomass-based and polyacrylonitrile-based knitted fabrics and woven fabrics) as precursors, and adopts ultrasonic-assisted phosphoric acid activation and carbonization processes to prepare activated carbon fiber cloths for liquid flow battery electrodes. The process is simple and suitable for industrial production. At the same time, the activated carbon fiber cloth prepared by the present invention achieves the goals of high specific surface area, high conductivity, high air permeability, and good mechanical self-supporting performance.

Description

Technical Field

[0001] The invention belongs to the field of electrode material preparation, and particularly relates to a preparation method and application of pre-oxidized fiber woven cloth-based activated carbon fiber for liquid flow battery electrodes. Background Art

[0002] The information disclosed in the background technology of the present invention only provides background technology related to the present invention and does not necessarily constitute the prior art known to ordinary technicians in the field.

[0003] Liquid flow batteries have the advantages of fast response time, good safety, long cycle life, and independent regulation of energy and power. They have great potential in large-scale energy storage fields such as wind power generation and energy storage systems, power grid peak regulation, and emergency power generation devices. As the site for electrochemical reactions in liquid flow batteries, the physical and chemical properties of electrode materials directly affect the overall performance of liquid flow batteries. Ideal liquid flow battery electrode materials should have high specific surface area, excellent electrical conductivity, good electrochemical activity, superior chemical stability, and high mechanical strength.

[0004] However, the common activated carbon fiber materials such as polyacrylonitrile-based, viscose-based and asphalt-based materials have complicated preparation processes, low conductivity, low specific surface area and poor mechanical properties, which greatly limits the electrochemical performance of liquid flow batteries. Summary of the invention

[0005] In order to solve the above problems, the present invention provides an activated carbon fiber cloth electrode material for liquid flow battery and its method and application, which solves the problems of complicated preparation process, low specific surface area, poor conductivity and mechanical self-supporting performance of activated carbon fiber for liquid flow battery electrodes in the prior art.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The first aspect of the present invention provides a method for preparing activated carbon fiber cloth for liquid flow battery electrodes by activating and carbonizing a pre-oxidized fiber woven cloth, comprising:

[0008] The pre-oxidized fiber woven fabric is ultrasonically impregnated in a phosphoric acid solution and dried once to obtain a pre-oxidized fiber fabric loaded with an activator;

[0009] The pre-oxidized silk cloth loaded with the activator is carbonized and activated under the protection of an inert atmosphere to obtain activated carbon fibers;

[0010] The activated carbon fibers are washed with water, dried twice, and carbonized under an inert atmosphere to obtain activated carbon fiber cloth.

[0011] In some embodiments, the phosphoric acid solution has a concentration of 10 wt % to 70 wt %.

[0012] In some embodiments, the ultrasonic immersion time is 0.5-24h.

[0013] In some embodiments, the primary drying temperature is 60-120°C.

[0014] In some embodiments, the carbonization activation temperature is 600-900° C., and the time is 0.5-6 h.

[0015] In some embodiments, the secondary drying is drying at 100-105° C. for 10-12 hours.

[0016] In some embodiments, the carbonization temperature is 1000-1500° C., and the time is 0.5-8 h.

[0017] In some embodiments, the inert atmosphere is nitrogen.

[0018] The second aspect of the present invention provides an activated carbon fiber cloth prepared by the above method. The activated carbon fiber cloth can be used as a liquid flow battery electrode.

[0019] The third aspect of the present invention provides the use of the above-mentioned activated carbon fiber cloth in the preparation of liquid flow battery electrodes or liquid flow batteries.

[0020] Beneficial Effects of the Invention

[0021] (1) The present invention uses pre-oxidized fiber woven fabric (including biomass-based and polyacrylonitrile-based knitted fabric and textile fabric) as a precursor, which has a wide source of raw materials, low cost, and excellent mechanical strength. The present invention uses ultrasound-assisted phosphoric acid activation and carbonization process to prepare activated carbon fiber cloth for liquid flow battery electrodes. The process is simple and suitable for industrial production. The activated carbon fiber cloth prepared by the present invention has high specific surface area, high conductivity, high air permeability and good mechanical self-supporting performance, and has excellent comprehensive performance.

[0022] (2) The present invention prepares activated carbon fiber cloth having high specific surface area, high conductivity, high air permeability and excellent mechanical self-supporting performance by combining ultrasound-assisted phosphoric acid activation and carbonization. The specific surface area of ​​the flow battery electrode of the present invention is 800-1556 m 2 / g, resistivity is 126~400mΩ·cm, air permeability is 24.65~27.31L / min, and tensile strength is 162.5~286.4Kpa. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] 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.

[0024] Figure 1is a flow chart of preparing activated carbon fiber for flow battery in Example 1-3 of the present invention;

[0025] Figure 2 The pre-oxidized fiber woven fabric used in the present invention includes but is not limited to biomass-based and polyacrylonitrile-based knitted fabrics and woven fabrics. DETAILED DESCRIPTION

[0026] 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.

[0027] 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.

[0028] Example 1

[0029] This embodiment provides a method for preparing an activated carbon fiber cloth with a high specific surface area, comprising:

[0030] Step 1: The pre-oxidized fiber woven fabric was ultrasonically impregnated in a 40 wt % phosphoric acid solution for 6 h, and then dried at 100° C. for 12 h.

[0031] Step 2: Activate the pre-oxidized silk cloth treated in step 1 at 750°C for 2h.

[0032] Step 3: The activated carbon fibers treated in step 2 are placed in deionized water for cleaning and dried at 100°C for 12 hours.

[0033] Step 4: Carbonize the activated carbon fiber cloth treated in step 3 at 1100°C for 2h.

[0034] The specific surface area of ​​the prepared activated carbon fiber is 1556 m 2 / g, resistivity is 225mΩ·cm, air permeability is 26.53L / min, and tensile strength is 200.5Kpa.

[0035] Example 2

[0036] This embodiment provides a method for preparing a high specific surface area activated carbon fiber cloth, comprising:

[0037] Step 1: The pre-oxidized fiber woven fabric was ultrasonically impregnated in a 40 wt % phosphoric acid solution for 6 h, and then dried at 100° C. for 12 h.

[0038] Step 2: Activate the pre-oxidized silk cloth treated in step 1 at 750°C for 2h.

[0039] Step 3: The activated carbon fibers treated in step 2 are placed in deionized water for cleaning and dried at 100°C for 12 hours.

[0040] Step 4: Carbonize the activated carbon fiber cloth treated in step 3 at 1200°C for 2h.

[0041] The specific surface area of ​​the prepared activated carbon fiber is 1420 m 2 / g, resistivity is 185mΩ·cm, air permeability is 26.84L / min, and tensile strength is 186.5Kpa.

[0042] Example 3

[0043] This embodiment provides a method for preparing a high specific surface area activated carbon fiber cloth, comprising:

[0044] Step 1: The pre-oxidized fiber woven fabric was ultrasonically impregnated in a 40 wt % phosphoric acid solution for 6 h, and then dried at 100° C. for 12 h.

[0045] Step 2: Activate the pre-oxidized silk cloth treated in step 1 at 750°C for 2h.

[0046] Step 3: The activated carbon fibers treated in step 2 are placed in deionized water for cleaning and dried at 100°C for 12 hours.

[0047] Step 4: Carbonize the activated carbon fiber cloth treated in step 3 at 1300°C for 2h.

[0048] The specific surface area of ​​the prepared activated carbon fiber is 1193m 2 / g, resistivity is 126mΩ·cm, air permeability is 27.31L / min, and tensile strength is 162.5Kpa.

[0049] Comparative Example 1

[0050] The difference between this comparative example and Example 1 is that this comparative example is not subjected to carbonization treatment after activation. The specific steps are as follows:

[0051] This comparative example provides a method for preparing activated carbon fiber cloth for liquid flow battery, comprising:

[0052] Step 1: The pre-oxidized fiber woven fabric was ultrasonically impregnated in a 40 wt % phosphoric acid solution for 6 h, and then dried at 100° C. for 12 h.

[0053] Step 2: Activate the pre-oxidized silk cloth treated in step 1 at 750°C for 2h.

[0054] Step 3: The activated carbon fibers treated in step 2 are placed in deionized water for cleaning and dried at 100°C for 12 hours.

[0055] The specific surface area of ​​the prepared activated carbon fiber cloth is 1874m 2 / g, resistivity is 4.23Ω·cm, air permeability is 24.65L / min, and tensile strength is 286.4Kpa. Although the comparative example has a higher specific surface area than the carbonized sample, its resistivity is much higher than that of the uncarbonized sample. This is because the carbonization process of the activated carbon fiber cloth is conducive to improving its graphite-like microcrystalline structure and reducing its resistivity.

[0056] Comparative Example 2

[0057] The difference between this comparative example and Example 1 is that this comparative example does not undergo phosphoric acid activation but is directly subjected to carbonization treatment.

[0058] The specific surface area of ​​the prepared activated carbon fiber cloth is 3.42 m 2 / g, resistivity is 198mΩ·cm, air permeability is 24.83L / min, and tensile strength is 324.7Kpa. It can be seen that the phosphoric acid activation process significantly increases the specific surface area of ​​the activated carbon fiber, and the carbonization process further increases the conductivity and air permeability of the activated carbon fiber cloth. Therefore, a porous carbon fiber cloth with excellent comprehensive performance can be prepared by combining ultrasound-assisted phosphoric acid activation and carbonization.

[0059] Comparative Example 3

[0060] The difference between this comparative example and Example 1 is that this comparative example does not perform ultrasound-assisted phosphoric acid activation, but simply performs phosphoric acid solution immersion activation and carbonization treatment.

[0061] The specific surface area of ​​the prepared activated carbon fiber cloth is 675m 2 / g, resistivity is 210mΩ·cm, air permeability is 25.45L / min, and tensile strength is 273.8Kpa. It can be seen that compared with ordinary impregnation, the use of ultrasonic assisted phosphoric acid activation and high temperature carbonization can better increase the specific surface area of ​​activated carbon fiber, and at the same time, the air permeability of activated carbon fiber cloth is also improved.

[0062] 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 activated carbon fiber cloth for flow battery electrodes by activating and carbonizing pre-oxidized fiber woven cloth, characterized in that: include: The pre-oxidized fiber woven fabric is ultrasonically impregnated in a phosphoric acid solution and dried once to obtain a pre-oxidized fiber fabric loaded with an activator; The pre-oxidized silk cloth loaded with the activator is carbonized and activated under the protection of an inert atmosphere to obtain activated carbon fibers; The activated carbon fibers are washed with water, dried twice, and carbonized under an inert atmosphere to obtain activated carbon fiber cloth.

2. The method for preparing flow battery electrodes by activating and carbonizing pre-oxidized fiber woven fabrics according to claim 1, characterized in that: The concentration of the phosphoric acid solution is 10wt%-70wt%.

3. The method for preparing flow battery electrodes by activating and carbonizing pre-oxidized fiber woven fabrics according to claim 1, characterized in that: The ultrasonic immersion time is 0.5-24h.

4. The method for preparing flow battery electrodes by activating and carbonizing pre-oxidized fiber woven fabrics according to claim 1, characterized in that: The primary drying temperature is 60-120°C.

5. The method for preparing flow battery electrodes by activating and carbonizing pre-oxidized fiber woven fabrics according to claim 1, characterized in that: The carbonization activation temperature is 600-900° C., and the time is 0.5-6 hours.

6. The method for preparing flow battery electrodes by activating and carbonizing pre-oxidized fiber woven fabrics according to claim 1, characterized in that: The secondary drying is performed at 100-105° C. for 10-12 hours.

7. The method for preparing flow battery electrodes by activating and carbonizing pre-oxidized fiber woven fabrics according to claim 1, characterized in that: The carbonization temperature is 1000-1500° C., and the time is 0.5-8 hours.

8. The method for preparing flow battery electrodes by activating and carbonizing pre-oxidized fiber woven fabrics according to claim 1, characterized in that: The inert atmosphere is nitrogen.

9. An activated carbon fiber cloth prepared by the method according to any one of claims 1 to 8.

10. Use of the activated carbon fiber cloth according to claim 9 in preparing liquid flow battery electrodes or liquid flow batteries.

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