Modified carbon fiber, preparation method thereof, and cement-based anode material containing modified carbon fiber

Abstract

The present invention discloses a modified carbon fiber, a preparation method thereof, and a cement-based anode material containing the modified carbon fiber, and belongs to the technical field of steel bar anti-corrosion materials. The preparation method of the modified carbon fiber provided by the present invention comprises the following steps: placing the degummed carbon fiber in a mixed solution of dopamine and tris(hydroxymethyl)aminomethane for reaction, washing and drying to obtain a polydopamine-coated carbon fiber; using the polydopamine-coated carbon fiber as a cathode and a copper sheet as an anode, electroplating in a copper ion electroplating solution, washing and drying to obtain the modified carbon fiber. The modified carbon fiber provided by the present invention has good quality and few defects. Compared with the carbon fiber before modification, the mechanical properties and electrical conductivity are improved. The cement-based anode material prepared by using the modified carbon fiber has high electrical conductivity and a high conductive percolation threshold, can achieve long-term electrochemical protection, and has good application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of steel bar anti-corrosion materials, and in particular to a modified carbon fiber and a preparation method thereof, and a cement-based anode material containing the modified carbon fiber. Background Art

[0002] The information disclosed in the background of the invention is only intended to enhance 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] Electrochemical protection technology plays an important role in the field of steel bar corrosion protection. Traditional electrochemical protection anode materials include stainless steel mesh, magnesium mesh, titanium mesh, zinc alloy materials, etc., which can effectively prevent the corrosion of steel bars. However, these metal mesh anode materials are prone to corrosion in the presence of external ions and cause secondary damage to the concrete structure. In addition, metal mesh also has disadvantages such as high cost and inconvenient construction.

[0004] Conductive cement-based composite materials as anode materials have the advantages of low cost, easy construction, and no corrosion. The resistivity of dry ordinary concrete is 6.5×10 5 ~11.4×10 5 Ω·cm, while carbonaceous conductive fillers such as carbon black (CB), carbon fibers (CF), carbon nanofibers (CNF), carbon nanotubes (CNT), and graphite can improve the conductivity of cement-based materials. Cement-based composites with carbon fibers as the primary conductive filler exhibit excellent mechanical properties, particularly tensile and flexural strength, and can reduce volume shrinkage caused by drying. Furthermore, they are corrosion-resistant, resisting erosion by chemicals and environmental factors.

[0005] However, carbon fiber is a non-metallic fiber with a much higher resistivity than metal, and its resistance has a certain temperature effect. In actual engineering applications, due to changes in the environment, climate, etc., the temperature changes, and the resistance of the cement-based anode material will also change accordingly. This will cause a significant change in the electric field during the electrochemical protection process, thereby affecting the effect of electrochemical protection.

[0006] Therefore, how to modify carbon fiber to improve its conductivity without damaging its mechanical properties, and to make the cement-based anode material prepared therefrom have good conductivity and resistance stability, is an urgent problem to be solved. Summary of the Invention

[0007] In view of this, the present invention provides a modified carbon fiber and a preparation method thereof, and a cement-based anode material containing the modified carbon fiber, which solves the problem that the existing carbon fiber-based conductive cement-based anode material has a large resistance and is easily affected by the environment, resulting in a reduced electrochemical protection effect.

[0008] In a first aspect, the present invention provides a method for preparing modified carbon fiber, comprising the following steps:

[0009] The debonded carbon fiber is placed in a mixed solution of dopamine and tris(hydroxymethyl)aminomethane for reaction, and then washed and dried to obtain a polydopamine-coated carbon fiber;

[0010] The polydopamine-coated carbon fiber is used as a cathode and a copper sheet is used as an anode, and electroplating is performed in a copper ion electroplating solution, and the product is obtained after washing and drying.

[0011] Preferably, the debonded carbon fiber is obtained by soaking the carbon fiber in an acetone solution to remove the glue; the specification of the carbon fiber is 12K, the diameter of the single fiber is 5 to 8 μm, and the length is 5 to 9 mm.

[0012] Preferably, in the mixed solution of dopamine and tris(hydroxymethyl)aminomethane, the concentration of dopamine is 1-3 g / L, and the concentration of tris(hydroxymethyl)aminomethane is 1-3 g / L; the pH of the mixed solution of dopamine and tris(hydroxymethyl)aminomethane is about 8.5.

[0013] Preferably, the mass ratio of the debonded carbon fiber to dopamine is 1 g: (4-6) g.

[0014] Preferably, the reaction temperature of placing the debonded carbon fiber in a mixed solution of dopamine and tris(hydroxymethyl)aminomethane is 10-40° C., and the reaction time is 20-40 hours.

[0015] Preferably, the solvent of the copper ion electroplating solution is water, and the copper ion electroplating solution includes copper sulfate, sodium citrate, ammonium chloride and sodium dodecyl sulfate, wherein the concentration of copper sulfate is 30-50 g / L, the concentration of sodium citrate is 40-60 g / L, the concentration of ammonium chloride is 6-10 g / L, the concentration of sodium dodecyl sulfate is 0.3-0.5 g / L, and the pH of the copper ion electroplating solution is 8-10.

[0016] Preferably, the electroplating voltage is 0.5 to 3 V, and the electroplating time is 0.5 to 2 h.

[0017] In a second aspect, the present invention provides modified carbon fibers prepared by the above-mentioned preparation method.

[0018] In a third aspect, the present invention provides a cement-based anode material comprising 80 to 100 parts of cement, 30 to 40 parts of water, 100 to 150 parts of sand, 0.1 to 0.5 parts of a water reducer and the above-mentioned modified carbon fiber, wherein the mass fraction of the modified carbon fiber is 0.15 to 1 wt% of the total mass of the cement-based anode material.

[0019] Preferably, the cement is sulphoaluminate cement, the sand is Chinese IOS standard sand, and the water reducer is polycarboxylate water reducer.

[0020] Preferably, the cement-based anode material also includes carbon black, the mass ratio of the modified carbon fiber and the carbon black is 1:(0.5-3), the total mass of the modified carbon fiber and the carbon black accounts for 0.2-1wt% of the total mass of the cement-based anode material; the particle size of the carbon black is 20-50nm.

[0021] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0022] (1) The modification method of the present invention is simple to operate and easy to mass-produce. The prepared modified carbon fiber has good quality and few defects. Compared with the carbon fiber before modification, the mechanical properties and conductivity are improved.

[0023] (2) The cement-based anode material prepared using the modified carbon fiber provided by the present invention has high conductivity, and can reduce the conductive percolation threshold of the cement-based anode material. It has excellent environmental stability, can achieve long-term electrochemical protection, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute undue limitations thereon. It is obvious that one of ordinary skill in the art could derive other drawings based on these drawings without inventive effort.

[0025] Figure 1 The infrared spectra of the debonded carbon fiber (non-glue CF) and the PDA-coated carbon fiber (PDA-CF) of Example 1 of the present invention are shown in FIG. 1 , where a is the wave number of 400 to 4000 cm -1 Infrared spectrum, b is the wave number of 700~2200cm -1 IR spectrum of

[0026] Figure 2 1 is a scanning electron microscope image of the unmodified carbon fiber (CF) and the PDA-coated carbon fiber (PDA-CF) of Example 1 of the present invention, wherein a is the unmodified carbon fiber (CF) and b is the PDA-coated carbon fiber (PDA-CF);

[0027] Figure 3 1 is a scanning electron microscope image of the modified carbon fiber of Example 1 of the present invention, wherein the magnification of Figure a is 100 times, and the magnification of Figure b is 1000 times;

[0028] Figure 4 1 is the X-ray diffraction (XRD) pattern of the unmodified carbon fiber (CF) and the modified carbon fiber (PDA-CF-Cu) of Example 1 of the present invention;

[0029] Figure 5 1 is a graph showing the tensile strength data of unmodified carbon fiber (CF), debonded carbon fiber (CF without glue), PDA-coated carbon fiber (PDA-CF), and modified carbon fiber (PDA-CF-Cu) according to Example 1 of the present invention;

[0030] Figure 6 1 is a graph showing the resistivity data of unmodified carbon fiber (CF), debonded carbon fiber (CF without glue), PDA-coated carbon fiber (PDA-CF), and modified carbon fiber (PDA-CF-Cu) according to Example 1 of the present invention;

[0031] Figure 7 2 is a graph showing the resistivity data of cement-based anode materials of Examples 2 to 7 and Comparative Examples 1 to 10 of the present invention;

[0032] Figure 8 14-day resistivity change diagram of the cement-based anode materials of Examples 3 to 5 and Comparative Examples 6 to 8 of the present invention;

[0033] Figure 9 Graph showing resistance changes of the conductive cement-based anode materials of Example 2, Examples 8 to 12, and Comparative Example 11 of the present invention as the ambient temperature changes;

[0034] Figure 10 This is a resistivity test chart of the conductive cement-based anode materials of Example 4, Examples 8 to 12, and Comparative Example 11 of the present invention. DETAILED DESCRIPTION

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

[0036] The present invention provides a method for preparing modified carbon fiber, comprising the following steps:

[0037] The debonded carbon fiber is placed in a mixed solution of dopamine and tris(hydroxymethyl)aminomethane for reaction, and then washed and dried to obtain a polydopamine-coated carbon fiber;

[0038] The polydopamine-coated carbon fiber is used as a cathode and a copper sheet is used as an anode, and electroplating is performed in a copper ion electroplating solution, and the product is obtained after washing and drying.

[0039] The existing technology makes it difficult to simultaneously improve both mechanical and electrical properties after modifying debonded carbon fibers. However, the present invention first modifies the carbon fibers by coating them with polydopamine, and then deposits copper crystals on them by electroplating. The prepared modified carbon fibers have high mechanical strength and high electrical conductivity, which is beneficial for their subsequent application.

[0040] During the carbon fiber production process, the carbon fibers must be sizing to reduce surface friction and prevent linting during transportation. However, commercial sizing agents are less effective in improving material properties. Therefore, it is necessary to first remove the commercial sizing agents used in the carbon fiber production process (i.e., desizing). The desizing carbon fibers described herein are obtained by desizing the carbon fibers by soaking them in an acetone solution. The specific desizing method for acetone soaking is not particularly limited in the present invention, and any acetone soaking desizing method known to those skilled in the art can be used.

[0041] In the present invention, the specification of the carbon fiber is 12K, the diameter of the single fiber is 5 to 8 μm, and the length is 5 to 9 mm. The present invention does not impose any special restrictions on the type of carbon fiber, and polyacrylonitrile-based carbon fiber is preferred.

[0042] In the present invention, in the mixed solution of dopamine and tris(hydroxymethyl)aminomethane, the concentration of dopamine is 1 to 3 g / L, and the concentration of tris(hydroxymethyl)aminomethane is 1 to 3 g / L; the pH of the mixed solution of dopamine and tris(hydroxymethyl)aminomethane is 8 to 10, specifically 8, 8.5, 9, 9.5 or 10.

[0043] In the present invention, the mass ratio of the debonded carbon fiber to dopamine is 1g:(4-6)g.

[0044] In the present invention, the reaction temperature of placing the debonded carbon fiber in a mixed solution of dopamine and tris(hydroxymethyl)aminomethane is 10 to 40°C, specifically 15°C, 20°C, 25°C (room temperature), 30°C, 35°C or 40°C, more preferably 20 to 30°C; and the reaction time is 20 to 40 hours. The mechanical properties of the carbon fiber will decrease after debonding. In the present invention, dopamine undergoes a self-polymerization reaction under alkaline conditions and adheres to the surface of the carbon fiber material to form a polydopamine-coated carbon fiber, thereby obtaining a modified carbon fiber with excellent mechanical properties.

[0045] The present invention does not impose any particular restrictions on the washing and drying processes after the autopolymerization reaction. Water washing is preferred to remove unreacted monomers and achieve a neutral pH on the carbon fiber surface. Drying is preferably performed at 50-90°C, and the drying time depends on the specific drying conditions, which is not particularly limited in the present invention.

[0046] In the present invention, the solvent of the copper ion electroplating solution is water, and the copper ion electroplating solution includes copper sulfate, sodium citrate, ammonium chloride and sodium dodecyl sulfate, wherein the concentration of copper sulfate is 30-50 g / L, the concentration of sodium citrate is 40-60 g / L, the concentration of ammonium chloride is 6-10 g / L, the concentration of sodium dodecyl sulfate is 0.3-0.5 g / L, and the pH value of the copper ion electroplating solution is 8-9. Copper sulfate, as the main electroplating solution, provides the necessary copper ions for the electroplating process, and these copper ions are the main components of the copper plating layer. Ammonium chloride, as a conductive salt, improves the conductivity of the electroplating solution, and at the same time, Cl - During the electroplating process, it effectively inhibits anode passivation, preventing hydroxide from generating oxygen and combining with copper to form cuprous oxide, which would otherwise hinder contact between the anode and the plating solution. The citrate in sodium citrate forms stable metal complex ions with copper sulfate, reducing the deposition rate of metal ions, resulting in finer crystallization of the coating, improving the dispersibility of the plating solution, and promoting anode dissolution. Sodium dodecyl sulfate reduces the solid-liquid interfacial tension between the electrode and the plating solution, ensuring even coverage of the plating solution on the carbon fiber surface, ensuring uniform plating, and reducing bubbles and defects.

[0047] In the present invention, the electroplating voltage is 0.5 to 3 V, and the electroplating time is 0.5 to 2 hours. A layer of copper crystals is uniformly deposited on the surface of the polydopamine-coated carbon fibers by electroplating, thereby imparting good electrical conductivity to the modified carbon fibers. The thickness of the electroplated layer is 2 to 8 μm.

[0048] The present invention does not impose any particular restrictions on the washing and drying process after electroplating. Washing is preferably performed with water to remove the electroplating solution remaining on the surface of the modified carbon fiber and to achieve a neutral pH on the surface of the modified carbon fiber. The drying temperature is preferably 50 to 90°C and the drying time is 3 to 10 hours.

[0049] The present invention also provides modified carbon fibers prepared by the above-mentioned preparation method. The modified carbon fibers have excellent mechanical properties and electrical conductivity, a tensile strength of more than 5000 MPa, and a resistivity of less than 0.1 Ω·cm.

[0050] The present invention provides a cement-based anode material, comprising 80 to 100 parts of cement, 30 to 40 parts of water, 100 to 150 parts of sand, 0.1 to 0.5 parts of a water reducer and the modified carbon fiber, wherein the mass fraction of the modified carbon fiber is 0.15 to 1 wt% of the total mass of the cement-based anode material.

[0051] In the present invention, the cement is sulphoaluminate cement, the sand is China IOS standard sand, and the water reducer is a polycarboxylate water reducer.

[0052] In the present invention, too little addition of modified carbon fiber will not significantly improve the conductivity of the material, and too high a mass fraction will not significantly improve the conductivity but will increase the cost. The mass fraction of the modified carbon fiber is preferably 0.2 to 0.6 wt%.

[0053] In the present invention, the cement-based anode material further comprises carbon black, wherein the mass ratio of the modified carbon fiber to the carbon black is 1:(0.5-3); the total mass of the modified carbon fiber and the carbon black accounts for 0.2-1 wt% of the total mass of the cement-based anode material; and the particle size of the carbon black is 20-50 nm. The carbon black (CB) has a granular shape, and the carbon fiber (CF) has a filamentous shape. The two carbon-based materials have a conductive synergistic effect, where the CB can disperse the CF and fill the microscopic pores between adjacent CFs, thereby providing effective conductive bridging capabilities. Furthermore, the CB has negative temperature coefficient thermistor properties (i.e., resistance decreases with increasing temperature), and the modified carbon fiber has positive temperature coefficient thermistor properties (i.e., resistance increases with increasing temperature). Therefore, the combination of the two can further increase the resistance stability of the cement-based anode material.

[0054] The present invention does not impose any particular limitation on the preparation method of the cement-based anode material, and any commonly used preparation method of cement-based anode materials in the art may be used.

[0055] The technical solution of the present invention is further described below with reference to specific embodiments.

[0056] In the following embodiments, the carbon fiber is a polyacrylonitrile-based carbon fiber (12K) produced by Kunshan Kosrui New Materials Co., Ltd., the monofilament diameter of the fiber is about 7 μm, and the surface is sized; copper sulfate, sodium citrate, sodium hydroxide, ammonium chloride, tris (hydroxymethyl) aminomethane and sodium dodecylsulfonate are analytical grade and produced by Sinopharm Chemical Reagent Co., Ltd.; dopamine hydrochloride is ≥98% pure and produced by Shanghai McLean Biochemical Co., Ltd.; acetone degumming agent is produced by Taiwan Tongsheng Enterprise Group; the anode is ≥9 The 9.9% copper plate was produced by Taizhou Chunshi New Materials Co., Ltd.; the cement was sulphoaluminate cement produced by Hebei Tangshan Polar Bear Building Materials Co., Ltd.; the sand was China IOS standard sand: cumulative sieve retention of 0% for 2.00mm, 7±5% for 1.60mm, 33±5% for 1.00mm, 67±5% for 0.50mm, 87±5% for 0.16mm, and 99±1% for 0.08mm. The water reducer used was a polycarboxylate water reducer produced by Beijing Jingxuan Technology Co., Ltd.; the carbon black particle size was 27-40nm, with a resistivity of ≤1.5Ω·cm, and was produced by Suqian Engu Nanotechnology Co., Ltd.

[0057] Example 1

[0058] This embodiment provides a method for preparing modified carbon fiber.

[0059] (1) placing polyacrylonitrile-based carbon fiber (CF) in an acetone desizing agent for 48 h to remove the sizing agent on the surface, then washing and drying to obtain desizing carbon fiber (desizing CF);

[0060] (2) 0.15 g of the debonded carbon fiber in step (1) was placed in 500 mL of a solution containing dopamine and Tris (tris(hydroxymethyl)aminomethane), with the dopamine concentration being 1.5 g / L, the tris(hydroxymethyl)aminomethane concentration being 1.2 g / L, and the solution pH being 8.5. The mixture was reacted at room temperature for 30 h, then washed with deionized water, and dried at 60 ° C for 12 h to obtain polydopamine (PDA)-coated carbon fiber (PDA-CF);

[0061] (3) copper sulfate, sodium citrate, ammonium chloride, sodium lauryl sulfate and water were mixed to prepare an electroplating solution, wherein the concentration of copper sulfate was controlled to be 40 g / L, the concentration of sodium citrate was controlled to be 45 g / L, the concentration of ammonium chloride was controlled to be 8 g / L, the concentration of sodium lauryl sulfate was controlled to be 0.4 g / L, and the pH of the solution was controlled to be about 8.0;

[0062] (4) The size of the copper sheet in the electroplating device is 80×60×0.3 mm, which serves as the anode, and the anode plate adopts a double-plate symmetrical and equidistant structure; the PDA-coated carbon fiber bundle prepared in step (2) is fixed on a U-shaped copper strip with an 80×60×0.3 mm frame width of 10 mm, which serves as the cathode; electroplating is carried out in the electroplating solution configured in step (3), the electroplating solution temperature is 25°C, the electroplating voltage is 1V, and after electroplating for 1 hour, the electroplated carbon fiber is washed with deionized water to neutrality and dried in a vacuum oven at 60°C for 4 hours to obtain modified carbon fiber (PDA-CF-Cu).

[0063] The debonded carbon fiber of step (1) and the PDA-coated carbon fiber of step (2) were subjected to infrared measurement, as shown in FIG. Figure 1 As shown in a and b, it can be seen that the FTIR spectrum of PDA-CF is between 1350 and 1200 cm -1 The tensile vibration peak belonging to aromatic amine CN appeared at . Scanning electron microscopy was performed on the unmodified carbon fiber and the PDA-coated carbon fiber of step (2). Figure 2As shown in the figure, it can be seen that the surface of the carbon fiber without PDA coating is relatively smooth, and the grooves extending along the axial direction on the surface are damage caused by the degumming process of the carbon fiber. In contrast, the surface grooves of the carbon fiber coated with PDA in step (2) have become shallower, and a layer of gelatinous film is present on the surface. These changes prove that the self-polymerization reaction of dopamine has successfully occurred and the carbon fiber has been successfully coated with PDA.

[0064] The modified carbon fiber obtained in step (4) was measured by scanning electron microscopy. Figure 3 As shown in a and b, it can be seen that the copper plating layer on the surface of the modified carbon fiber is evenly distributed and tightly stacked, showing its excellent plating quality.

[0065] X-ray diffraction (XRD) experiments were performed on the unmodified carbon fiber and the modified carbon fiber obtained in step (4). The obtained XRD spectra were as follows: Figure 4 As shown in the figure, it can be seen that the diffraction peaks of Cu appear at 43.67°, 50.79° and 74.44°, corresponding to the (111), (200) and (220) crystal planes of Cu, respectively. The diffraction peaks of Cu2O appear at 36.5°, 42.34° and 61.48°, corresponding to the (111), (200) and (220) crystal planes of Cu2O, respectively. In addition, by observing the diffraction peak heights of each substance, it can be seen that the main substance coated on the carbon fiber surface is copper.

[0066] The tensile strength and resistivity of the unmodified carbon fiber (CF), the debonded carbon fiber (CF) of step (1), the PDA-coated carbon fiber (PDA-CF) of step (2), and the modified carbon fiber (PDA-CF-Cu) of step (4) were measured, respectively. Figure 5 and Figure 6 As shown in the figure, it can be seen that the tensile strength of PDA-CF-Cu is improved compared with that of CF; the conductivity of PDA-CF-Cu is increased by 25 times compared with that of CF.

[0067] Example 2

[0068] This embodiment provides a cement-based anode material prepared from the modified carbon fiber of Example 1. The cement-based anode material includes a mixture of the following components, measured in parts by weight: 80 parts of cement, 32 parts of water, 120 parts of sand, 0.4 parts of a water reducer, and the modified carbon fiber; the mass fraction of the modified carbon fiber in the cement-based anode material is 0.15 wt%.

[0069] First, the modified carbon fibers are mixed with cement and some sand, using a dry mixing method to evenly disperse the modified carbon fibers. The dispersed carbon fibers and the remaining sand are then added to a blender and mixed evenly. Finally, water and a water reducer are added to the blender and mixed evenly to obtain a cement-based mortar mixture. The resulting cement-based mortar mixture is then filled into a mold, smoothed, and the copper electrode material inserted. After standing for 24 hours, the mold is removed and cured to obtain the cement-based anode material.

[0070] Example 3

[0071] The difference between this embodiment and embodiment 2 is that the mass fraction of the modified carbon fiber in the cement-based anode material in this embodiment is 0.2 wt %.

[0072] Example 4

[0073] The difference between this embodiment and embodiment 2 is that the mass fraction of the modified carbon fiber in the cement-based anode material in this embodiment is 0.4 wt %.

[0074] Example 5

[0075] The difference between this embodiment and embodiment 2 is that the mass fraction of the modified carbon fiber in the cement-based anode material in this embodiment is 0.6 wt %.

[0076] Example 6

[0077] The difference between this embodiment and embodiment 2 is that the mass fraction of the modified carbon fiber in the cement-based anode material in this embodiment is 0.8 wt %.

[0078] Example 7

[0079] The difference between this embodiment and embodiment 2 is that the mass fraction of the modified carbon fiber in the cement-based anode material in this embodiment is 1.0 wt %.

[0080] Example 8

[0081] The difference between this embodiment and Example 2 is that this embodiment also includes carbon black, and the total mass of the modified carbon fiber and carbon black accounts for 0.4wt% of the total mass of the cement-based anode material, wherein the mass ratio of the modified carbon fiber to the carbon black is 1:1.

[0082] Example 9

[0083] The difference between this embodiment and Example 8 is that the mass ratio of the modified carbon fiber to the carbon black in this embodiment is 1:2.

[0084] Example 10

[0085] The difference between this embodiment and Example 8 is that the mass ratio of modified carbon fiber to carbon black in this embodiment is 2:1.

[0086] Example 11

[0087] The difference between this embodiment and Example 8 is that the mass ratio of the modified carbon fiber to the carbon black in this embodiment is 2:3.

[0088] Example 12

[0089] The difference between this embodiment and Example 8 is that the mass ratio of the modified carbon fiber to the carbon black in this embodiment is 3:2.

[0090] Example 13

[0091] The difference between this embodiment and embodiment 4 is that, in this embodiment, there are 100 parts of cement, 40 parts of water, 140 parts of sand, and 0.5 parts of water reducing agent.

[0092] Comparative Example 1

[0093] The difference between this comparative example and Example 2 is that no modified carbon fiber is added in this comparative example.

[0094] Comparative Example 2

[0095] The difference between this comparative example and Example 2 is that the mass fraction of the modified carbon fiber in the cement-based anode material in this comparative example is 0.05 wt %.

[0096] Comparative Example 3

[0097] The difference between this comparative example and Example 2 is that the mass fraction of the modified carbon fiber in the cement-based anode material in this comparative example is 0.1 wt %.

[0098] Comparative Example 4

[0099] The difference between this comparative example and comparative example 3 is that this comparative example uses unmodified carbon fiber.

[0100] Comparative Example 5

[0101] The difference between this comparative example and Example 2 is that this comparative example uses unmodified carbon fiber.

[0102] Comparative Example 6

[0103] The difference between this comparative example and Example 3 is that this comparative example uses unmodified carbon fiber.

[0104] Comparative Example 7

[0105] The difference between this comparative example and Example 4 is that this comparative example uses unmodified carbon fiber.

[0106] Comparative Example 8

[0107] The difference between this comparative example and Example 5 is that this comparative example uses unmodified carbon fiber.

[0108] Comparative Example 9

[0109] The difference between this comparative example and Example 6 is that this comparative example uses unmodified carbon fiber.

[0110] Comparative Example 10

[0111] The difference between this comparative example and Example 7 is that this comparative example uses unmodified carbon fiber.

[0112] Comparative Example 11

[0113] The difference between this comparative example and Example 8 is that this comparative example does not contain modified carbon fiber, but only contains carbon black, and the mass of carbon black accounts for 0.4 wt% of the total mass of the cement-based anode material.

[0114] The resistivity of the cement-based anode materials of Examples 2 to 7 and Comparative Examples 1 to 10 was measured. Figure 7 As shown in the figure, it can be seen that with the increase of carbon fiber addition, the resistivity of the cement-based anode material decreases significantly, but there is a conductive percolation threshold. Compared with the cement-based anode material prepared by CF, the cement-based anode material prepared by PDA-CF-Cu has a lower percolation threshold and better conductivity.

[0115] The resistivity of the cement-based anode materials of Examples 3 to 5 and Comparative Examples 6 to 8 was monitored for 14 days, and the resistivity on the 1st, 3rd, 7th and 14th day was measured respectively. Figure 8 It can be seen that with the increase of age, the resistivity of the cement-based anode material shows an upward trend, and the resistivity of the cement-based anode material prepared by PDA-CF-Cu increases slowly, and the conductivity is more stable.

[0116] Figure 9 The following graphs show the resistance change of the conductive cement-based anode materials as a function of ambient temperature for Examples 2, Examples 8-12, and Comparative Example 11. Carbon black and modified carbon fibers exhibit different thermistor properties, and their resistivity changes with temperature follow different patterns, as shown for PDA-CF-Cu and CB in the figure. Furthermore, the resistivity of cement-based anode materials varies with temperature when the conductive filler ratio is varied. However, when the carbon black:modified carbon fiber ratio is 1:1, the resistivity hardly changes with temperature, demonstrating excellent environmental stability.

[0117] Figure 10The resistivity test graphs for the conductive cement-based anode materials of Examples 4, 8-12, and Comparative Example 11 show the mass ratios of modified carbon fiber to carbon black, respectively, at 1:0, 1:1, 1:2, 2:1, 2:3, 3:2, and 0:1. As can be seen from the graph, the resistivity of the cement-based anode material doped with carbon black alone (Comparative Example 11) is the highest, while the resistivity of the conductive cement-based anode material doped with modified carbon fiber is significantly reduced. The optimal ratio of modified carbon fiber to carbon black not only reduces resistivity but also improves the environmental stability of cement-based anode materials.

[0118] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A cement-based anode material, characterized in that: The cement-based anode material comprises 80-100 parts of cement, 30-40 parts of water, 100-150 parts of sand, 0.1-0.5 parts of a water-reducing agent, and modified carbon fibers. The cement-based anode material further comprises carbon black, and the total mass of the modified carbon fibers and the carbon black accounts for 0.4 wt% of the total mass of the cement-based anode material. The particle size of the carbon black is 20 to 50 nm; The mass ratio of the modified carbon fiber to carbon black is 1:1; The modified carbon fiber has a tensile strength of more than 5000 MPa and a resistivity of less than 0.1 Ω·cm; The preparation method of the modified carbon fiber comprises the following steps: The debonded carbon fiber is placed in a mixed solution of dopamine and tris(hydroxymethyl)aminomethane for reaction, and then washed and dried to obtain a polydopamine-coated carbon fiber; The polydopamine-coated carbon fiber is used as a cathode and a copper sheet is used as an anode, and electroplating is performed in a copper ion electroplating solution, and the product is obtained after washing and drying.

2. The cement-based anode material according to claim 1, wherein The cement is sulphoaluminate cement, the sand is Chinese ISO standard sand, and the water reducer is polycarboxylate water reducer.

3. The cement-based anode material according to claim 1, wherein The debonded carbon fiber is obtained by soaking the carbon fiber in an acetone solution to remove the glue; the specification of the carbon fiber is 12K, the diameter of the single fiber is 5-8 μm, and the length is 5-9 mm.

4. The cement-based anode material according to claim 1, wherein In the mixed solution of dopamine and tris(hydroxymethyl)aminomethane, the concentration of dopamine is 1-3 g / L, and the concentration of tris(hydroxymethyl)aminomethane is 1-3 g / L; the pH of the mixed solution of dopamine and tris(hydroxymethyl)aminomethane is 8-9.

5. The cement-based anode material according to claim 1, wherein The mass ratio of the degummed carbon fiber to dopamine is 1g:(4-6)g; the reaction temperature of placing the degummed carbon fiber in a mixed solution of dopamine and tris(hydroxymethyl)aminomethane is 10-40°C, and the reaction time is 20-40h.

6. The cement-based anode material according to claim 1, wherein The solvent of the copper ion electroplating solution is water, and the copper ion electroplating solution includes copper sulfate, sodium citrate, ammonium chloride and sodium dodecyl sulfate, wherein the concentration of copper sulfate is 30-50 g / L, the concentration of sodium citrate is 40-60 g / L, the concentration of ammonium chloride is 6-10 g / L, the concentration of sodium dodecyl sulfate is 0.3-0.5 g / L, and the pH of the copper ion electroplating solution is 8-10.

7. The cement-based anode material according to claim 1, wherein The electroplating voltage is 0.5-3V, and the electroplating time is 0.5-2h.

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