Electrode material based on ink direct writing 3D printing and preparation method thereof

Abstract

The application belongs to the technical field of electrode materials, and specifically discloses an electrode material based on ink direct writing 3D printing and a preparation method thereof. By controlling the rheological property of silver / silver chloride ink in ink direct writing, silver / silver chloride filaments of different sizes are printed. The silver / silver chloride ink in filament form is used to print silver / silver chloride rods or sheets with high surface area in a hollow shape. After degreasing and sintering at different temperatures, a silver / silver chloride reference electrode with high specific surface area and high mechanical strength is obtained. The reference electrode has higher specific surface area and mechanical strength, stronger impact and vibration resistance, lower polarization resistance, better long-term stability, higher polarization resistance of the electrode body with the same mass, minimum potential deviation under the same current, and minimum open circuit potential drift in natural seawater with certain temperature and salinity.

Description

Technical Field

[0001] This invention belongs to the field of electrode material technology, specifically relating to an electrode material based on ink direct writing 3D printing and its preparation method. Background Technology

[0002] In cathodic protection systems for marine metal structures, such as oil platforms, subsea pipelines, docks, and ships, it is necessary to measure parameters such as protection potential, protection current density, sacrificial anode current, and anode operating potential to determine the protection status of the structure. The protection potential is obtained by comparing the metal structure with a reference electrode, while the protection current and anode current can be calculated by measuring the potential (field) gradient and seawater resistivity. Typically, the measurement of the metal structure potential and cathodic protection potential requires a reference electrode accuracy (stability) of ≤±10mV; therefore, higher requirements are placed on the stability of the reference electrode. For this reason, it is essential to find and develop high-precision, high-stability reference electrodes for seawater environments.

[0003] For a long time, silver / silver chloride electrodes have been considered ideal reference electrodes in seawater. However, due to the influence of bromide ions, silver / silver chloride electrodes in seawater initially exhibit potential instability. This is because silver chloride tends to further transform into a silver chloride-silver bromide solid solution in the seawater environment. To obtain a reference electrode with better thermodynamic stability in seawater, the solid phase composition was calculated according to the standard seawater thermodynamic model and the solid / liquid equilibrium constant, and a novel silver / silver chloride reference electrode with high reversibility and good stability in the seawater environment was fabricated. Currently, this reference electrode has been successfully applied to the cathodic protection system of marine engineering.

[0004] Currently, the commonly used silver / silver chloride reference electrodes in the field of marine engineering mainly employ three manufacturing processes: electrodeposition reduction method, powder pressing method, and hot dipping coating. (1) Electrodeposition method. Under laboratory conditions, a silver wire is immersed in a dilute hydrochloric acid solution, and an anodic current is applied to the silver wire to dissolve it, thereby depositing silver chloride on its surface to form a silver / silver chloride reference electrode. This silver chloride film deposited on its surface by the dissolution process of the silver wire begins to fall off after reaching a certain thickness, usually only a few to a dozen micrometers thick, so its service life is short and it is mostly used for potential measurement under laboratory conditions. (2) Powder pressing method. The powder pressing method is to press silver powder, silver chloride, and silver bromide powder in a certain proportion using a tablet press, which is a relatively common manufacturing process. However, the mixed powder of silver powder, silver chloride, and silver bromide that relies on pressure to bond has poor mechanical properties, especially as seawater gradually penetrates into the powder and gradually falls off, resulting in a shortened service life, with an average service life of less than 3 to 5 years, which is difficult to meet the needs of long-term cathodic protection measurement of marine engineering facilities. (3) Hot dipping coating method. This method involves rolling silver rods or silver mesh into a rod shape, immersing it in molten silver chloride or silver chloride slurry, and then cooling it to form the desired shape. Although the silver / silver chloride or silver chloride reference electrode produced by this method has sufficient mechanical strength, the area on its electrode surface participating in the equilibrium reaction is small, and the large number of silver rods or silver mesh inside cannot play a role in the dissolution equilibrium reaction, thus leading to a waste of precious metals.

[0005] The dissolution equilibrium reaction shows that the reversibility of the silver / silver chloride reference electrode depends on a sufficiently large reaction area (specific surface area) on the electrode surface. This significantly improves its polarization resistance and maintains sufficient stability in a strong cathodic protection electric field. Furthermore, the strength of the reference electrode must be considered to ensure it can withstand the mechanical vibrations and seawater impacts that may be encountered in engineering applications. In marine engineering, the potential drift of solid electrodes in seawater with different salinity and temperature can introduce measurement errors. Therefore, it is necessary to optimize the electrode fabrication process to reduce this drift. Summary of the Invention

[0006] To address the aforementioned technical issues, this invention proposes an electrode material and its preparation method based on ink direct writing 3D printing. This electrode has a higher specific surface area and mechanical strength, resulting in stronger resistance to impact and vibration, lower polarization resistance, better long-term stability, higher polarization resistance for the same mass of electrode body, and minimal potential shift under the same current. In natural seawater with a certain temperature and salinity, its open-circuit potential drift is minimal.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0008] An electrode material based on ink direct writing 3D printing includes a metal ink made of high-purity silver chloride powder and silver powder, which is used as a printing substrate to 3D print the electrode material.

[0009] The present invention also provides a method for preparing the above-mentioned electrode material, comprising the following steps:

[0010] S1. Prepare metal ink by mixing high-purity silver chloride powder with silver powder;

[0011] S1.1 Preparation of high-purity silver chloride powder: After drying the silver chloride powder, grind and sieve it in a ball mill. Spray the unsieved material with anhydrous ethanol, let it stand for 10 minutes, and then carry out the next round of grinding. After each grinding, spray the unsieved material with anhydrous ethanol until the unsieved drug appears as flakes.

[0012] S1.2: Weigh silver chloride and silver powder according to the proportion, mix them evenly in a sealed container, pour the mixed powder into a heated polyethylene aqueous solution, stir thoroughly, then add carboxymethyl cellulose, polyethylene glycol and guar gum in sequence, and continue to stir evenly to obtain a metal ink loaded with silver / silver chloride powder.

[0013] S2. Electrode blanks are prepared by 3D printing with metal ink: The metal ink loaded with silver / silver chloride powder is 3D printed onto the substrate. The metal ink is delivered into a conical micro-nozzle through a syringe. The syringe is installed on a micro-injection pump to control the flow rate of the metal ink flowing out of the syringe. The injection pump is installed on the bio-3D printer and moves in the xyz axis direction to obtain an electrode blank of the preset shape.

[0014] S3. Degrease and sinter the electrode blank to obtain the finished electrode material.

[0015] Preferably, in step S1.1, silver chloride is heated to 250-270°C at room temperature at a heating rate of 10°C / min and then dried in the dark, followed by grinding in a ball mill at a speed of 150-250 r / min.

[0016] Preferably, in the mixed powder of silver chloride and silver powder in S1.2, the mass fraction of silver chloride is 33.3%-66.7%, the particle size of silver chloride is less than 250 mesh, and the particle size of silver powder is less than 1250 mesh.

[0017] Preferably, the mass fraction of the polyethylene aqueous solution in S1.2 is 8%-10%, and the temperature of the polyethylene aqueous solution is 70-90℃.

[0018] Preferably, the mass of the polyethylene aqueous solution, carboxymethyl cellulose, polyethylene glycol, and guar gum in S1.2 is 15%-25% of the total mass of the metallic ink.

[0019] Preferably, in S2, the inner diameter of the conical plastic micro-nozzle is 400-800 μm, the extrusion speed of the injection pump is 0.02-0.04 mm / s, the electrode printing thickness is not less than 9 layers, the electrode design diameter is 10 mm, and the filling density is 30-40%.

[0020] Preferably, the specific steps of degreasing in S3 are as follows:

[0021] S3.1 Initial stage: The temperature is increased from room temperature to 230℃ at a rate of 1℃ / min ± 20%, and then dried at 230℃ for 30 min to ensure that the electrode blank is heated evenly and there is no temperature difference between the inside and outside.

[0022] S3.2 Intermediate stage: Increase the temperature from 230℃ to 400℃ at a heating rate of 0.5~1℃ / min, and hold at that temperature for at least 2 hours.

[0023] Preferably, in step S3, the sintering temperature is increased from 400°C to 500°C at a heating rate of 5°C / min ± 10%, and held for 12h ± 30min to allow the grains to grow and distribute uniformly, ultimately obtaining the finished electrode material.

[0024] The beneficial effects of this invention are:

[0025] Compared with reference electrodes prepared by traditional electrodeposition reduction, powder pressing, and hot dipping methods, this invention, under the premise of the same mass, controls the rheological properties of silver / silver chloride ink for direct writing, prints silver / silver chloride wires of different sizes, and uses the wire-like silver / silver chloride ink to print hollow silver / silver chloride rods or sheets with high surface area. After degreasing and sintering at different temperatures, a silver / silver chloride reference electrode with high specific surface area and high mechanical strength is obtained. This reference electrode has a higher specific surface area and mechanical strength, making it more resistant to impact and vibration, with lower polarization resistance and better long-term stability. For the same mass of electrode body, it has higher polarization resistance, the smallest potential shift under the same current, and the smallest open-circuit potential drift in natural seawater with a certain temperature and salinity. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 Fabrication steps (a) and structural schematic diagram (b) for a silver / silver chloride reference electrode;

[0028] Figure 2Rheological property test graphs for 75 wt.% (a), 80 wt.% (b) and 85 wt.% (c) powder-loaded inks;

[0029] Figure 3 Images of printed samples of powder-loaded inks at 75 wt.% (a), 80 wt.% (b), and 85 wt.% (c);

[0030] Figure 4 Macro and micro images of a degreased sintered sample of ink loaded with 80 wt.% powder: (a) macro, (b) micro;

[0031] Figure 5 Gas adsorption-desorption curves of degreased sintered samples of ink loaded with 80 wt.% powder: (a) isothermal linear plot, (b) BET surface area plot;

[0032] Figure 6 Tensile specimen images of 3D printed (a) and powder-pressed (b) samples;

[0033] Figure 7 Polarization resistance test curves and fitting curves for 3D printed reference electrodes;

[0034] Figure 8 A 90-day potential test curve for a 3D-printed reference electrode;

[0035] Figure 9 Potential test curves of a 3D-printed reference electrode in 3.0%–3.5% NaCl over 30 days. Detailed Implementation

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0037] like Figure 1 As shown in the following embodiments, the silver / silver chloride reference electrode is fabricated according to the method steps provided by the present invention using a pre-designed silver / silver chloride reference electrode structure.

[0038] Example 1

[0039] S1: High-purity silver chloride is placed in an oven at room temperature and baked at 260°C in the dark for 1 hour.

[0040] The temperature rise rate in step S1 is approximately 10°C / min.

[0041] S2: Grind the dried silver chloride in a ball mill at a speed of 150 r / min for 5 minutes. After sieving, grind for another cycle after a 10-minute interval. Repeat this grinding cycle 4 times. For the last 2 grinding cycles, spray anhydrous ethanol to cool the powder and obtain silver chloride powder that passes through a 250-mesh sieve.

[0042] S3: Weigh 5g of silver chloride powder and 10g of silver powder using an electronic balance. Premix the silver chloride and silver powder for 1 minute, then pour the mixture into a beaker containing 4g of polyethylene aqueous solution, which has been preheated to 70°C in a water bath. Stir the powder thoroughly until the solution is still in a suspension state. Then, add carboxymethyl cellulose, polyethylene glycol, and guar gum in sequence, and continue stirring until homogeneous to obtain a silver / silver chloride powder-loaded metal ink.

[0043] In step S3, the mass fraction of silver chloride in the mixed powder is 33.3%.

[0044] In step S3, the silver chloride particle size is less than 250 mesh, and the silver powder particle size is less than 1250 mesh.

[0045] The mass fraction of the polyvinyl alcohol aqueous solution in step S3 is 8%;

[0046] The mass of the polyvinyl alcohol aqueous solution, carboxymethyl cellulose, polyethylene glycol, and guar gum is 25% of the total mass of the metallic ink, wherein the carboxymethyl cellulose is 0.4g, the polyethylene glycol is 0.6g, and the guar gum is 0.1g.

[0047] S4: Ink Direct Writing 3D Printing Molding Process: The metal ink loaded with the silver / silver chloride powder is 3D printed onto the substrate. The metal ink is delivered into a 400μm inner diameter conical plastic micro-nozzle through a 5ml plastic syringe. The syringe is mounted on a micro-injection pump to control the flow rate of the metal ink flowing out of the syringe. The injection pump is mounted on the bio-3D printer and moves in the xyz axis direction to obtain an electrode blank of a preset shape.

[0048] In step S4, the inner diameter of the conical plastic micro-nozzle is 400 μm, the extrusion speed is 0.02 mm / s, the printing thickness is 9 layers, the electrode diameter is 10 mm, and the fill density is 30%.

[0049] S5: Place the printed electrode into a muffle furnace and raise the temperature from room temperature to the set temperature of 230°C at a rate of approximately 1°C / min, holding at the set temperature for 30 minutes. Then adjust the set temperature to 400°C, raising the temperature at a rate of approximately 1°C / min, and holding for 2 hours; subsequently, set the temperature to 500°C, raising the temperature at a rate of approximately 5°C / min, and holding for 12 hours. After the holding period, turn off the muffle furnace and allow the electrode to cool naturally to room temperature inside the furnace.

[0050] The silver / silver chloride powder-loaded metal ink prepared by the above method exhibits significant shear-thinning behavior, with a shear-thinning coefficient of 0.22 and a consistency index of 890 obtained through fitting. After reaching a shear stress of 2846.77 Pa, the viscosity decreases sharply, and a relatively stable region, termed yield stress, is observed before reaching the critical shear stress. Furthermore, the storage modulus of the ink is higher than its loss modulus, indicating that the ink exhibits elastic or solid-like behavior. The 3D printing reference electrode prepared by the above method shows a significantly increased specific surface area of ​​0.0796 m² compared to commercially available reference electrodes. 2 The surface area is more than 50 times that of commercially available electrodes. This high specific surface area represents a greater number of chemically reactive centers, resulting in superior electrochemical performance of the 3D-printed reference electrode. Electrodes prepared using the same mass of material prepared using the above method exhibit potential fluctuations within 1 mV over 90 days. The maximum difference in the electrode's spontaneous potential (without a salt bridge) in solutions with different salinities ranging from 2.8% to 3.5% is less than 1 mV. In a 3.5% sodium chloride solution at 25°C, the electrode's polarization resistance is 12.82 Ωvcm. 2 The tensile strength has been increased to 24.4 MPa, which is more than 20 times that of commercially available electrodes.

[0051] Example 2

[0052] S1: High-purity silver chloride is placed in an oven at room temperature and baked at 250°C in the dark for 1 hour.

[0053] The temperature rise rate in step S1 is approximately 11°C / min.

[0054] S2: Grind the dried silver chloride in a ball mill at 200 r / min for 5 minutes. After sieving, grind for another 10 minutes and then continue grinding for one cycle. Repeat this grinding cycle 4 times. For the last 2 grinding cycles, spray anhydrous ethanol to cool the powder and obtain silver chloride powder that passes through a 250 mesh sieve.

[0055] S3: Weigh 7.5g of silver chloride powder and 7.5g of silver powder using an electronic balance. Premix the silver chloride and silver powder for 1 minute, then pour the mixture into a beaker containing 2.75g of polyethylene aqueous solution, which has been preheated to 80°C in a water bath. Stir the powder thoroughly until the solution is still in a suspension state. Then, add carboxymethyl cellulose, polyethylene glycol, and guar gum in sequence, and continue stirring until homogeneous to obtain a silver / silver chloride powder-loaded metal ink.

[0056] In step S3, the mass fraction of silver chloride in the mixed powder is 50%.

[0057] In step S3, the silver chloride particle size is less than 250 mesh, and the silver powder particle size is less than 1250 mesh.

[0058] The mass fraction of the polyvinyl alcohol aqueous solution in step S3 is 9%;

[0059] The mass of the polyvinyl alcohol aqueous solution, carboxymethyl cellulose, polyethylene glycol, and guar gum is 20% of the total mass of the metallic ink, wherein the carboxymethyl cellulose is 0.5g, the polyethylene glycol is 0.5g, and the guar gum is 0.1g.

[0060] S4: Ink Direct Writing 3D Printing Molding Process: The metal ink loaded with the silver / silver chloride powder is 3D printed onto the substrate. The metal ink is delivered into a 600μm inner diameter conical plastic micro-nozzle through a 5ml plastic syringe. The syringe is mounted on a micro-injection pump to control the flow rate of the metal ink flowing out of the syringe. The injection pump is mounted on the bio-3D printer and moves in the xyz axis direction to obtain an electrode blank of a preset shape.

[0061] In step S4, the inner diameter of the conical plastic micro-nozzle is 600 μm, the extrusion speed is 0.03 mm / s, the printing thickness is 10 layers, the electrode diameter is 10 mm, and the fill density is 35%.

[0062] S5: Place the printed electrode into a muffle furnace and raise the temperature from room temperature to the set temperature of 220°C at a rate of approximately 0.8°C / min, holding at this temperature for 60 minutes. Then adjust the set temperature to 390°C, raising the temperature at a rate of approximately 0.75°C / min, holding for 3 hours; subsequently, set the temperature to 490°C, raising the temperature at a rate of approximately 4.5°C / min, holding for 11.5 hours. After the holding period, turn off the muffle furnace and allow the electrode to cool naturally to room temperature inside the furnace.

[0063] The silver / silver chloride powder-loaded metal ink prepared by the above method exhibits significant shear-thinning behavior, with a shear-thinning coefficient of 0.18 and a consistency index of 5278 obtained through fitting. After reaching a shear stress of 7373.4 Pa, the viscosity decreases sharply, and a relatively stable region, termed yield stress, is observed before reaching the critical shear stress. Furthermore, the storage modulus of the ink is higher than its loss modulus, indicating that the ink exhibits elastic or solid-like behavior. The 3D printing reference electrode prepared by the above method shows a significantly increased specific surface area of ​​0.0811 m² compared to commercially available reference electrodes. 2 The surface area is more than 50 times that of commercially available electrodes. This high specific surface area represents a greater number of chemically reactive centers, resulting in superior electrochemical performance of the 3D-printed reference electrode. Electrodes prepared using the same mass of material prepared using the above method exhibit potential fluctuations within 1 mV over 90 days. The maximum difference in the electrode's spontaneous potential (without a salt bridge) in solutions with different salinities ranging from 2.8% to 3.5% is less than 1 mV. In a 3.5% sodium chloride solution at 25°C, the electrode's polarization resistance is 13.76 Ω·cm. 2The tensile strength has been increased to 25.8 MPa, which is more than 20 times that of commercially available electrodes.

[0064] Example 3

[0065] S1: High-purity silver chloride is placed in an oven at room temperature and baked at 270°C in the dark for 1 hour.

[0066] The temperature rise rate in step S1 is approximately 12°C / min.

[0067] S2: Grind the dried silver chloride in a ball mill at a speed of 250 r / min for 5 minutes. After sieving, grind for another cycle after a 10-minute interval. Repeat this grinding cycle 4 times. For the last 2 grinding cycles, spray anhydrous ethanol to cool the powder and obtain silver chloride powder that passes through a 250-mesh sieve.

[0068] S3: Weigh 10g of silver chloride powder and 5g of silver powder using an electronic balance. Premix the silver chloride and silver powder for 1 minute, then pour the mixture into a beaker containing 2g of polyethylene aqueous solution, which has been preheated to 90℃ in a water bath. Stir the powder thoroughly until the solution is still in a suspension state. Then, add carboxymethyl cellulose, polyethylene glycol, and guar gum in sequence, and continue stirring until homogeneous to obtain a silver / silver chloride powder-loaded metal ink.

[0069] In step S3, the mass fraction of silver chloride in the mixed powder is 66.7%.

[0070] In step S3, the silver chloride particle size is less than 250 mesh, and the silver powder particle size is less than 1250 mesh.

[0071] The mass fraction of the polyvinyl alcohol aqueous solution in step S3 is 10%;

[0072] The mass of the polyvinyl alcohol aqueous solution, carboxymethyl cellulose, polyethylene glycol, and guar gum is 15% of the total mass of the metallic ink, wherein the carboxymethyl cellulose is 0.6g, the polyethylene glycol is 0.4g, and the guar gum is 0.1g.

[0073] S4: Ink Direct Writing 3D Printing Molding Process: The metal ink loaded with the silver / silver chloride powder is 3D printed onto the substrate. The metal ink is delivered into a conical plastic micro-nozzle with an inner diameter of 800μm through a 5ml plastic syringe. The syringe is mounted on a micro-injection pump to control the flow rate of the metal ink flowing out of the syringe. The injection pump is mounted on the bio-3D printer and moves in the xyz axis direction to obtain an electrode blank of a preset shape.

[0074] In step S4, the inner diameter of the conical plastic micro-nozzle is 800 μm, the extrusion speed is 0.04 mm / s, the printing thickness is 11 layers, the electrode diameter is 10 mm, and the fill density is 40%.

[0075] S5: Place the printed electrode into a muffle furnace and raise the temperature from room temperature to the set temperature of 240℃ at a rate of approximately 1.2℃ / min, holding at the set temperature for 120 min. Then adjust the set temperature to 410℃, raising the temperature at a rate of approximately 0.5℃ / min, holding for 4 h; subsequently, set the temperature to 510℃, raising the temperature at a rate of approximately 5.5℃ / min, holding for 12.5 h. After the holding period, turn off the muffle furnace and allow the electrode to cool naturally to room temperature inside the furnace.

[0076] The silver / silver chloride powder-loaded metal ink obtained by this method exhibits significant shear-thinning behavior, with a shear-thinning coefficient of 0.16 and a consistency index of 31644 obtained through fitting. After reaching a shear stress of 21294.3 Pa, the viscosity decreases sharply, and a relatively stable region, termed yield stress, is observed before reaching the critical shear stress. Furthermore, the storage modulus of the ink is higher than its loss modulus, indicating that the ink exhibits elastic or solid-like behavior. The 3D printing reference electrode prepared by the above method has a significantly increased specific surface area of ​​0.0854 m² compared to commercially available reference electrodes. 2 The surface area is more than 50 times that of commercially available electrodes. This high specific surface area represents a greater number of chemically reactive centers, resulting in superior electrochemical performance of the 3D-printed reference electrode. Electrodes prepared using the same mass of material prepared using the above method exhibit potential fluctuations within 1 mV over 90 days. The maximum difference in the electrode's spontaneous potential (without a salt bridge) in solutions with different salinities ranging from 2.8% to 3.5% is less than 1 mV. In a 3.5% sodium chloride solution at 25°C, the electrode's polarization resistance is 14.13 Ω·cm. 2 The tensile strength has been increased to 26.7 MPa, which is more than 20 times that of commercially available electrodes.

[0077] The following conclusions can be drawn from the comparison of the electrode materials prepared in the three embodiments described above:

[0078] Depend on Figure 2 (a) The viscosity-shear stress curve shows that under a certain shear stress, the viscosity drops sharply. A relatively stable region, called yield stress, is observed before reaching the critical shear stress. The ink with a higher percentage of silver and silver chloride powder loading has a higher yield stress than the ink with a lower percentage of powder loading. Figure 2 (b) shows that the viscosity of the three inks decreases with increasing shear rate, which is known as shear thinning behavior. This is important for inks to be extruded through the nozzle and to maintain their shape after deposition. Figure 2 (c) The frequency scanning test curves show that both the storage modulus G' and the loss modulus G” increase with the increase of the silver and silver chloride powder loading percentage and frequency. The storage modulus is higher than the loss modulus, indicating that the ink exhibits elastic or solid-like behavior, which is very important for the extruded part to maintain its shape and support its own weight during the printing process.

[0079] Figure 3 (a) is a printed sample of Example 1 of the present invention. It can be seen that the 75wt.% powder-loaded ink has a low powder load, and the ink filaments flow and deform rapidly after printing, causing the adjacent pillars to merge and collapse and fail to form. Figure 3 (b) is a printed sample of Example 2 of the present invention. It can be seen that the ink with 80wt.% powder load is well printed with filaments, the gap between the pillars is appropriate, there is no displacement or fusion, the structure does not collapse, and the adjacent layers are well bonded together to form a shape. Figure 3 (c) is a printed sample of Example 3 of the present invention. It can be seen that the ink with 85wt.% powder load is difficult to extrude due to the high powder load, and the ink filaments are intermittently broken and cannot be formed.

[0080] Figure 4 (a) and (b) are macroscopic and microscopic images of the printed sample after degreasing and sintering in Example 2 of the present invention. It can be seen that there is obvious metallic luster and few defects on the electrode surface. The microscopic image shows the interface generated between silver chloride and silver particles when silver chloride melts. Silver chloride and silver are evenly distributed on the surface.

[0081] Figure 5 The curve for the reference electrode obtained in Example 2 was tested using the nitrogen adsorption BET method, and its specific surface area was 0.0811 m². 2 / g, while the electrode (a disc with a thickness of 1.75mm and a diameter of 15mm) prepared using the same mass of Ag / AgCl powder by the traditional powder pressing method has a specific surface area of ​​0.00158m². 2 / g, Example 2 of the present invention increases the specific surface area of ​​the reference electrode by as much as 51 times, which greatly increases the number of chemical reaction active centers, thereby making it more conducive to improving the electrochemical performance of the electrode.

[0082] Figure 6 Table 1 shows the tensile test results of the 3D printed reference electrode and the powder-pressed sample in Example 2. It can be seen that the tensile strength of the 3D printed reference electrode is 25.8 MPa, which is 22.8 times that of the powder-pressed electrode, and the strength is greatly improved.

[0083] Figure 7 The 3D-printed reference electrode used in Example 2 has a polarization resistance fitting result of 13.76 Ω·cm. 2 Compared to powder-pressed electrodes, it reduces costs by 75%.

[0084] Figure 8 The 3D-printed reference electrode of Example 2 maintained a potential fluctuation within 1mV throughout a 90-day stability test.

[0085] Figure 9The 3D-printed reference electrode of Example 2 has a potential that remains stable within 1 mV in 3.0%-3.5% NaCl for 30 minutes.

[0086] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not describe all details exhaustively, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification.

Claims

1. A method for preparing an electrode material based on ink direct writing 3D printing, characterized by, The method comprises the following steps: S1, mixing high-purity silver chloride powder with silver powder to prepare metal ink; S1.1, preparing high-purity silver chloride powder: baking and drying silver chloride at room temperature at a temperature increasing rate of 10℃ / min to 250-270℃ in the dark, grinding in a ball mill at a rotating speed of 150-250r / min, spraying anhydrous ethanol on the un-screened material, and then carrying out the next round of grinding after standing for 10min, and spraying anhydrous ethanol on the un-screened material after each subsequent grinding until flaky material appears in the un-screened material; S1.2: weighing silver chloride and silver powder according to a proportion, uniformly mixing in a sealed container, and then adding the mixed powder into polyethylene aqueous solution which has been heated, wherein the mass fraction of the silver chloride in the mixed powder is 33.3%-66.7%, the particle size of the silver chloride is less than 250 mesh, the particle size of the silver powder is less than 1250 mesh, the mass fraction of the polyethylene aqueous solution is 8%-10%, and the temperature of the polyethylene aqueous solution is 70-90℃, fully stirring, and then sequentially adding carboxymethyl cellulose, polyethylene glycol and guar gum, and continuously stirring until uniform, to obtain silver / silver chloride powder loaded metal ink, wherein the mass of the polyethylene aqueous solution, the carboxymethyl cellulose, the polyethylene glycol and the guar gum is 15%-25% of the total mass of the metal ink; S2, using the metal ink to 3D print to prepare an electrode blank: the silver / silver chloride powder loaded metal ink is 3D printed onto a substrate by being delivered into a conical micro-nozzle through a syringe, the syringe is installed on a micro-injection pump to control the flow rate of the metal ink flowing out of the syringe, the injection pump is installed on a biological 3D printer to move in x-y-z axial directions, and an electrode blank with a preset shape is obtained; the inner diameter of the conical plastic micro-nozzle is 400-800μm, the extrusion speed of the injection pump is 0.02-0.04mm / s, the electrode printing thickness is not less than 9 layers, the electrode design diameter is 10mm, and the filling density is 30-40%; S3, degreasing and sintering the electrode blank to obtain a finished electrode material; The specific steps of degreasing are as follows: S3.1, initial stage: increasing the temperature from room temperature to 230℃ at a rate of 1℃ / min±20%, and drying at 230℃ for 30min to make the electrode blank evenly heated without temperature difference between the inside and the outside; S3.2, intermediate stage: increasing the temperature from 230℃ to 400℃ at a rate of 0.5-1℃ / min, and keeping the temperature for at least 2h; Sintering: increasing the temperature from 400℃ to 500℃ at a rate of 5℃ / min±10%, and keeping the temperature for 12h±30min to make the crystal grains uniformly grow and distribute, and finally obtain the finished electrode material.

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