A high-density corrosion-resistant electrode paste and a preparation method thereof

Abstract

The present application relates to the technical field of electrode paste, in particular to a high-density corrosion-resistant electrode paste and a preparation method thereof. The anthracite and petroleum coke are subjected to plasma etching and coated with carbon nanotubes to form a conductive network, and the flake graphite powder is subjected to silane modification to strengthen the aggregate interface; the carboxylated carbon quantum dots are modified by amide groups, and then coupled with polyimide, medium-temperature pitch and aluminate coupling agent to form a composite binder; on the one hand, the amide groups of the carbon quantum dots form strong pi-pi conjugation with the imide groups of the polyimide to improve the interface bonding force; on the other hand, the aluminate coupling agent bridges the aggregate and the binder interface to improve the infiltration effect; in the composite antioxidant, TiB2 and boric acid form a stable protective film at high temperature to inhibit oxidation; in addition, the carbon layer is coated on the silicon powder to delay the volume expansion reaction of silicon; the components synergize with each other to solve the bottleneck that the traditional electrode paste is difficult to balance the density and corrosion resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrode paste, in particular to a high-density corrosion-resistant electrode paste and a preparation method thereof. BACKGROUND

[0002] In a submerged arc furnace, the carbon electrode is the core part of the submerged arc furnace, and the electrode plays a role in conducting current and converting electrical energy into heat energy in the submerged arc furnace. In industrial production, the electric current is input into the furnace through the electrode to generate an electric arc, and the electric arc is mainly used to release heat and smelt ferroalloy and calcium carbide products at high temperature. The quality of the electrode directly affects the production of the product, and the electrode is mainly made of electrode paste (self-baking electrode) as the main raw material, which is sintered (baked) by the submerged arc furnace producer. The electrode paste (self-baking electrode) is mainly made of anthracite, anode scrap, graphite powder, petroleum coke, pitch coke, and coal pitch as the main raw material, and is prepared into electrode paste products through batching, kneading, and molding. The electrode paste is loaded into the electrode cylinder which has been installed on the submerged arc furnace, and is sintered (baked) into a functional carbon electrode by relying on the joule heat generated by the current and the conduction heat and radiation heat in the furnace during the production process of the submerged arc furnace. The submerged arc furnace conducts a large current (up to tens of thousands of amperes) through the electrode paste, and the low porosity can avoid the electrode fracture caused by local overheating. The dense structure can reduce the "conductive bottleneck" caused by the porosity and reduce the energy loss when the current passes through. The electrode paste works in a high-temperature (usually 800-2000℃) and strong reducing or oxidizing atmosphere, and possibly in a corrosive medium environment, and the corrosion resistance directly affects the service life, conductivity efficiency, and production safety of the electrode. The traditional electrode paste often relies on a single anti-corrosion additive (such as SiC, Al2O3, etc.) and anti-corrosion particles to enhance the corrosion resistance, which is easy to form pores between the particles, reduce the density, and is difficult to balance the density and corrosion resistance. SUMMARY

[0003] In view of the deficiencies of the prior art, the present application provides a high-density corrosion-resistant electrode paste and a preparation method thereof. The anthracite and petroleum coke are subjected to plasma etching, and a carbon nanotube is coated to form a conductive network. The flaky graphite powder is subjected to silane modification to strengthen the aggregate interface. The carboxylated carbon quantum dots are modified by amide groups, and then coupled with polyimide, medium-temperature pitch, and aluminic ester coupling agent to form a composite binder. On the one hand, the amide groups of the carbon quantum dots form a strong π-π conjugation effect with the imide groups of the polyimide to improve the interface bonding force. On the other hand, the aluminic ester coupling agent bridges the aggregate and the binder interface to improve the wetting effect. In the composite antioxidant, TiB2 and boric acid form a stable protective film at high temperature to inhibit oxidation. In addition, the silicon powder is coated with a carbon layer to delay the volume expansion reaction of silicon. The components synergize with each other to solve the bottleneck that the traditional electrode paste is difficult to balance the density and corrosion resistance.

[0004] To achieve the above-mentioned purposes, the present application adopts the following technical solutions:

[0005] In a first aspect, the application provides a high-density corrosion-resistant electrode paste, comprising the following steps:

[0006] S1, pretreating anthracite and petroleum coke to obtain mixed aggregate, coating carbon nanotubes on the surface of the mixed aggregate to obtain carbon-coated modified aggregate; modifying flake graphite powder by silane to obtain modified flake graphite powder;

[0007] S2, mixing carboxylated carbon quantum dots solution, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS), adding ethylenediamine under nitrogen atmosphere, reacting at a first set temperature, and dialyzing to obtain amido carbon quantum dots;

[0008] S3, melting polyimide resin and medium temperature pitch at a second set temperature, mixing with the amido carbon quantum dots and aluminate coupling agent at a third set temperature to obtain a composite binder; mixing TiB2 nanoparticles with boric acid to obtain a composite antioxidant; stirring and reacting silicon powder and formaldehyde at a set pH to obtain carbon-coated silicon powder;

[0009] S4, blending and kneading the carbon-coated modified aggregate, modified flake graphite powder, and nanocarbon spheres with the composite binder, adding the composite antioxidant and carbon-coated silicon powder, aging, adding hydrophobic fumed silica, and mixing at a fourth set temperature to obtain electrode paste slurry; pressing the electrode paste slurry under gradient pressure, demolding after shaping to obtain electrode paste blanks; pre-carbonizing the electrode paste blanks in a nitrogen atmosphere to obtain the high-density corrosion-resistant electrode paste.

[0010] In a feasible implementation scenario, the particle size of the anthracite in S1 is 3-8 mm, the particle size of the petroleum coke is 0.5-3 mm, and the mass ratio of the anthracite to the petroleum coke is 6:(2.5-3); the pretreatment is Ar plasma etching for 5 min; the specific method for coating carbon nanotubes is: immersing the mixed aggregate in a carbon nanotube dispersion liquid, ultrasonic stirring for 20 min, and filtering and drying; the carbon nanotube dispersion liquid contains 2wt%-3wt% carbon nanotubes and 0.8wt%-1wt% sodium dodecylbenzenesulfonate.

[0011] The traditional electrode paste only conducts current through physical contact between aggregates, which is prone to form "conductive bottleneck" due to the gap between interfaces. In the present application, the surface of anthracite and petroleum coke is bombarded by high-energy particles through plasma etching, which breaks the carbon-carbon bond and reacts with the trace oxygen in the Ar atmosphere to form oxygen-containing functional groups, increases the active sites on the surface of the aggregate, and improves the interfacial bonding strength with carbon nanotubes, filling the contact gap between aggregates. Carbon nanotubes are combined with oxygen-containing functional groups on the surface of the aggregate through van der Waals force, and sodium dodecylbenzenesulfonate in the carbon nanotube dispersion prevents carbon nanotubes from agglomerating through electrostatic repulsion, allowing them to adsorb uniformly on the surface of the aggregate and form a continuous conductive network. At the same time, the surface of the modified flake graphite powder is coated with an organic silane layer, which is connected to the carbon nanotube network through intermolecular forces. The nano-scale structure of the flake graphite powder can fill the fine pores not covered by the carbon nanotube network. Through the synergistic effect of the three, the contact area for current conduction is increased, the interfacial resistance is reduced, and the interfacial bonding between aggregates is strengthened through the bridging effect of carbon nanotubes, reducing the contact failure caused by vibration or thermal expansion. Thus, the overall conductivity is improved, and the structural stability of the electrode paste is enhanced, which meets the working condition requirements of high-current conduction in the electric furnace.

[0012] In a feasible implementation scenario, the particle size of the flake graphite powder in S1 is 5-20 μm, the silane modification treatment uses an ethanol aqueous solution of KH-560 with a concentration of 5%, and the mass of KH-560 is 0.3%-0.5% of the mass of the flake graphite powder. The silane modification treatment is carried out at 80°C for 2-3 h, and then at 120°C for 1 h under a nitrogen atmosphere.

[0013] High-speed shearing breaks the agglomerates of graphite flakes, and the siloxane groups of KH-560 undergo hydrolysis in the ethanol aqueous solution: Si(OR)3+ 3H2O → Si(OH)3+ 3ROH. The silicon hydroxyl groups generated by hydrolysis undergo dehydration condensation with the hydroxyl groups on the surface of the graphite: -Si-OH + HO-Graphite → -Si-O-Graphite + H2O, forming an organic silane coating on the surface and improving the compatibility of the graphite with the subsequent composite binder. The reaction is promoted at 80°C, and the silane coating is further solidified at 120°C under a nitrogen atmosphere, enhancing the interfacial bonding strength.

[0014] In a feasible implementation scenario, the concentration of the carboxylated carbon quantum dot solution in S2 is 15wt%-20wt%, and the mass-volume ratio of the carboxylated carbon quantum dot solution, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, N-hydroxysuccinimide, and ethylenediamine is 50 mL:(1.8-2) g:(1-1.2) g:3 mL.

[0015] In a possible implementation, the first set temperature in S2 is 60℃, and the reaction time of the first set temperature is 3-4h; the molecular weight cut-off of the dialysis is 3500-4000Da, and the dialysis time is 48-72h.

[0016] The carboxylated carbon quantum dots are activated by an EDC / NHS activation system. EDC reacts with the carboxyl groups (-COOH) on the surface of the carbon quantum dots to generate an active ester intermediate (-COO-EDC), and NHS stabilizes the active ester intermediate and reduces the reaction energy barrier. The amino groups (-NH2) of ethylenediamine attack the carbonyl carbon of the active ester to generate an amide bond (-CONH-) through a nucleophilic substitution reaction, so that the amino groups of ethylenediamine are subjected to amidation reaction, and an amide functional group is introduced on the surface of the carbon quantum dots, thereby improving the compatibility and interfacial action of the carbon quantum dots with the polyimide resin. Dialysis (molecular weight cut-off: 3500-4000Da) is used to remove unreacted small molecule reagents, thereby improving the purity of the carbon quantum dots.

[0017] In a possible implementation, the second set temperature in S3 is 110-120℃, the third set temperature is 80-90℃, and the mixing time at the third set temperature is 30-60min; the mass ratio of the polyimide resin, the medium-temperature pitch, the amido-carbon quantum dots, and the aluminate coupling agent is 40:60:(2-2.2):1.5; the molecular weight of the polyimide resin is 1500-3500Da; and the aluminate coupling agent is DL-411-A.

[0018] The polyimide resin is mixed with the medium-temperature pitch to form a composite bonding system with high-temperature stability and fluidity. The amido-carbon quantum dots form a π-π conjugation effect with the imide groups of the polyimide resin through the amide groups, the lipophilic groups of the aluminate coupling agent (DL-411-A) are combined with the binder, the hydrophilic groups are subjected to a hydrolysis reaction to generate aluminum hydroxyl groups, and the aluminum hydroxyl groups are combined with the hydroxyl groups on the surface of the aggregate or the amide groups of the carbon quantum dots, thereby reducing the interfacial energy between the binder and the aggregate, bridging the interface between the binder and the aggregate, and improving the wettability. The amido-carbon quantum dots are uniformly dispersed in the binder, and the intermolecular forces are used to enhance the cohesion of the binder.

[0019] In a possible implementation, the mass ratio of the TiB2 nanoparticles to boric acid in S3 is 3:(8-10), the particle size of the TiB2 nanoparticles is 50-100nm, the mass ratio of the silicon powder to formaldehyde is 1:(4-5), the particle size of the silicon powder is 2-8μm, the set pH is 8-9, the stirring time is 60-90min, and the stirring speed is 500-800rpm.

[0020] TiB2 nanoparticles mixed with boric acid, TiB2 provides an oxidation-resistant core skeleton at high temperatures, and boric acid undergoes dehydration reaction at high temperature to form a glassy protective film B2O3: 2H3BO3→B2O3+3H2O; B2O3 and TiB2 cooperatively form a dense B-Ti-O composite oxide layer, inhibiting the diffusion of oxygen into the material interior, delaying the oxidation reaction rate, and covering the material surface to prevent oxygen permeation.

[0021] Silicon powder and formaldehyde undergo polycondensation reaction under alkaline conditions to form a hydroxymethyl formaldehyde intermediate, which undergoes condensation reaction with the hydroxyl groups on the surface of the silicon powder, gradually forming a three-dimensional carbon structure and coating the surface of the silicon powder to form a carbon layer coating structure. The carbon layer can delay the volume expansion reaction of silicon at high temperature, and at the same time improve the compatibility of silicon powder and binder.

[0022] In a feasible implementation scenario, the mass ratio of the carbon-coated modified aggregate, modified flake graphite powder, nano-carbon sphere, composite binder, composite antioxidant, carbon-coated silicon powder, and hydrophobic fumed silica described in S4 is 100:30:5:(100-105):(4-5):4:0.5; the temperature for blending and kneading is 145-155℃, the rotation speed is 80rpm, and the time is 30-40min; the curing is carried out at 180℃ and a vacuum degree of-0.09MPa, the curing time is 1h, the fourth set temperature is 110℃, and the mixing time at the fourth set temperature is 15min.

[0023] The carbon-coated modified aggregate, modified flake graphite powder, and composite binder are blended and kneaded at 145-155℃, the viscosity of the binder decreases at high temperature, and the fluidity increases, penetrating into the fine gaps of the aggregate through capillary action and filling the gaps between the aggregate; when cured at 180℃ under vacuum (-0.09MPa), the bubbles in the slurry expand and are expelled, reducing the porosity, and the hydrophobic fumed silica is dispersed in the slurry when mixed, further filling the small pores and improving the density.

[0024] In a feasible implementation scenario, the gradient pressure described in S4 includes: 3MPa pressure for 2min; 10MPa pressure for 5min; 30MPa pressure for 10min; the temperature for forming is 140℃, the temperature for demolding is 80℃; the temperature for pre-carbonization treatment is 280-300℃, and the time is 1.5-2h.

[0025] 3MPa low pressure for 2min to make the slurry initial spread, 10MPa medium pressure for 5min to remove the interface air, 30MPa high pressure for 10min to promote the close accumulation of aggregate and the sufficient contact of binder, gradient pressure to avoid the slurry splashing and local density uneven caused by pressure sudden rise, elastic buffer pad to absorb vibration energy reflection, make the pressure uniform transmission to the slurry each part; 140℃ forming temperature to ensure the binder in the appropriate viscosity state, conducive to densification, 80℃ demolding temperature to reduce the material internal stress, prevent the body cracking.

[0026] Pre-carbonization under nitrogen atmosphere, slow release of volatile components in the binder, light components of medium temperature pitch volatilize, heavy components of medium temperature pitch occur polycondensation reaction to form polycyclic aromatic hydrocarbon structure; polyimide resin occurs cyclization reaction, amide group carbon quantum dots and carbon skeleton of the binder form covalent bond connection, enhance the overall structure strength, nitrogen protection prevents the material from being oxidized at high temperature, at the same time, preliminary crosslinking reaction occurs, forming stable carbon skeleton, improving the structural stability of the electrode paste.

[0027] In the second aspect, the application provides a high-density corrosion-resistant electrode paste.

[0028] Beneficial technical effects:

[0029] The application provides a high-density corrosion-resistant electrode paste preparation method, first introducing oxygen-containing functional groups into anthracite and petroleum coke by plasma etching, and coating carbon nanotubes to form a conductive network, and then modifying the flake graphite powder with silane, so that the aggregate and the flake graphite powder synergize with each other, thereby expanding the contact area of current conduction and reducing the interface resistance, and strengthening the interface bonding between the aggregates through the bridging effect of the carbon nanotubes to reduce the contact failure caused by vibration or thermal expansion, thereby improving the overall conductivity and structural stability of the electrode paste; the carboxylated carbon quantum dots are modified with amide groups to form a composite binder with polyimide resin, medium temperature pitch and aluminate coupling agent, on the one hand, the amide groups of the carbon quantum dots form strong π-π conjugation with the imide groups of the polyimide to improve the interface bonding, and on the other hand, the aluminate coupling agent bridges the interface between the aggregate and the binder to improve the wetting effect; in the composite antioxidant, TiB2 and boric acid form a stable protective film at high temperature to inhibit oxidation; in addition, the carbon layer is coated on the silicon powder to delay the volume expansion reaction of silicon, thereby synergistically enhancing the corrosion resistance of the electrode paste; the components synergize with each other to solve the bottleneck of traditional electrode paste that is difficult to balance the density and corrosion resistance, and realize the comprehensive performance improvement of high density and corrosion resistance. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The comparison chart of the high-density corrosion-resistant electrode paste of Example 1 and Comparative Example 1 after immersion test in 10% sodium hydroxide.

[0031] Reference numerals: 1, high-density corrosion-resistant electrode paste of Example 1; 2, high-density corrosion-resistant electrode paste of Comparative Example 1. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions and beneficial effects to be solved in the present application more clear and explicit, the present application will be further described in detail below in conjunction with embodiments. However, this should not be understood as limiting the scope of the present application to the following examples. All other embodiments obtained by those of ordinary skill in the art without making creative labor on the premise of not departing from the method idea of the present application belong to the scope of protection of the present application.

[0033] In the present application, the terms used in the present application are merely for the purpose of describing specific embodiments, and are not intended to limit the present application.

[0034] The singular forms "is", "or", "a", "an", and "the" used in the present application are intended to include the plural forms, unless the context clearly indicates otherwise.

[0035] In addition, if the terms "first", "second" appear, they are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0036] The following will specifically describe a high-density corrosion-resistant electrode paste and a preparation method thereof provided by the present application in conjunction with different embodiments.

[0037] The particle size of the anthracite is 3-8 mm, the particle size of the petroleum coke is 0.5-3 mm, the particle size of the flake graphite powder is 5-20 μm, and the particle size of the TiB2nanoparticles is 50-100 nm; the particle size of the silicon powder is 2-8 μm; the nitrogen adsorption specific surface area of the hydrophobic fumed silica is 150±25 m 2 / g, the pH of the suspension is 4-6, the volatile matter at 105°C is ≤1.5%, the tap density is 40-60 g / L, and the carbon content is 4.5-6.5.

[0038] Example 1

[0039] A preparation method of a high-density corrosion-resistant electrode paste, comprising the following steps:

[0040] 1. The anthracite and the petroleum coke are mixed in a mass ratio of 6:2.7 and then placed in a plasma etching device, Ar gas is introduced, the power is set to 500 W, and etching is performed for 5 min to obtain mixed aggregates. The mixed aggregates are immersed in a carbon nanotube dispersion liquid containing 2.5 wt% carbon nanotubes and 0.9 wt% sodium dodecylbenzenesulfonate, ultrasonic treatment is performed for 10 min, and then stirring is performed at 100 r / min for 10 min to obtain carbon-coated modified aggregates.

[0041] 2. The flake graphite powder is sheared at high speed for 10 min at 3000 r / min, immersed in an ethanol aqueous solution with a concentration of 5% of KH-560, the mass of KH-560 is 0.4% of the mass of the flake graphite powder, and after reaction at 80℃ for 2.5 h, the reaction is continued for 1 h at 120℃ under a nitrogen atmosphere to obtain modified flake graphite powder;

[0042] 3. The carboxylated carbon quantum dot solution with a concentration of 18 wt%, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide are mixed, and then ethylenediamine is added dropwise under a nitrogen atmosphere; the mass-volume ratio of the carboxylated carbon quantum dot solution, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, N-hydroxysuccinimide and ethylenediamine is 50 mL:1.9 g:1.1 g:3 mL; after the reaction is completed, the reaction system is placed in a dialysis bag with a molecular weight cut-off of 3800 Da, dialyzed with deionized water for 60 h, and freeze-dried to obtain amido carbon quantum dots;

[0043] 4. The polyimide resin with a molecular weight of 2500 Da and the medium temperature pitch are respectively melted at 115℃, mixed with the amido carbon quantum dots and DL-411-A at 85℃ for 45 min, and the mass ratio of the polyimide resin, the medium temperature pitch, the amido carbon quantum dots and the aluminic ester coupling agent is 40:60:2.1:1.5 to obtain a composite binder; TiB2 nanoparticles, anhydrous ethanol and boric acid are mixed in a mass ratio of 3:4:9 to obtain a composite antioxidant;

[0044] 5. Silicon powder and formaldehyde are mixed in a mass ratio of 1:4.5, adjusted to pH=8.5 with an ammonia chloride buffer solution (ammonia water and ammonium chloride in a mass ratio of 3:1), and stirred at 700 rpm for 75 min to obtain carbon-coated silicon powder;

[0045] 6. The carbon-coated modified aggregate, the modified flake graphite powder, the nanocarbon spheres and the composite binder are blended and kneaded at 150℃ and 80 rpm for 35 min, the composite antioxidant and the carbon-coated silicon powder are added, and the mixture is cured at 180℃ and a vacuum degree of-0.09 MPa for 1 h, the hydrophobic fumed silica is added and mixed at 110℃ for 15 min, and the mass ratio of the carbon-coated modified aggregate, the modified flake graphite powder, the nanocarbon spheres, the composite binder, the composite antioxidant, the carbon-coated silicon powder and the hydrophobic fumed silica is 100:30:5:102:4.5:4:0.5 to obtain electrode paste slurry; the electrode paste slurry is pressed in a mold at a pressure of 3 MPa for 2 min, at a pressure of 10 MPa for 5 min and at a pressure of 30 MPa for 10 min, and then shaped at 140℃, and demolded at 80℃ to obtain an electrode paste green body;

[0046] 7. Pre-carbonize the electrode paste blank at 290℃ for 1.5h in a nitrogen atmosphere to obtain the high-density corrosion-resistant electrode paste.

[0047] Performance test:

[0048] The high-density corrosion-resistant electrode paste prepared in Example 1 was subjected to the following corrosion resistance test:

[0049] Acid resistance: soak in 5% sulfuric acid at room temperature for 72h, weigh before and after, calculate the mass loss rate, and record the appearance change; another electrode paste sample was soaked in 30% hydrochloric acid at 60℃ for 48h, weighed before and after, calculated the mass loss rate, and recorded the appearance change;

[0050] Alkali resistance: soak in 10% sodium hydroxide at room temperature for 72h, weigh before and after, calculate the mass loss rate, and record the appearance change; another electrode paste sample was soaked in 40% potassium hydroxide at 80℃ for 48h, weighed before and after, calculated the mass loss rate, and recorded the appearance change;

[0051] Salt resistance: soak in 10% sodium chloride at room temperature for 168h, weigh before and after, calculate the mass loss rate, and record the appearance change;

[0052] Organic solvent resistance: soak in toluene at room temperature for 168h, weigh before and after, calculate the mass loss rate, and record the appearance change;

[0053] The test results are shown in Table 1.

[0054] Table 1 Test results of corrosion resistance performance of Example 1

[0055]

[0056] Example 2

[0057] A method for preparing a high-density corrosion-resistant electrode paste, comprising the following steps:

[0058] 1. Mix the anthracite and petroleum coke in a mass ratio of 6:2.5, then place them in a plasma etching device, introduce Ar gas, set the power to 500W, and etch for 5min to obtain mixed aggregate. The mixed aggregate is immersed in a carbon nanotube dispersion liquid containing 2wt% carbon nanotubes and 0.8wt% sodium dodecylbenzenesulfonate, ultrasonic for 10min, and then stirred at 100r / min for 10min to obtain carbon-coated modified aggregate;

[0059] 2. High-speed shear the flake graphite powder at 3000r / min for 10min, immerse it in an ethanol aqueous solution with a concentration of 5% KH-560, the mass of KH-560 is 0.3% of the mass of flake graphite powder, react at 80℃ for 2h, and then continue to react at 120℃ under nitrogen atmosphere for 1h to obtain modified flake graphite powder;

[0060] 3. The carboxylated carbon quantum dot solution with a concentration of 15wt%, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide were mixed, and then ethylenediamine was added dropwise under a nitrogen atmosphere; the mass-volume ratio of the carboxylated carbon quantum dot solution, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, N-hydroxysuccinimide and ethylenediamine was 50mL:1.8g:1g:3mL; the reaction was carried out at 60℃ for 3h; after the reaction was completed, the reaction system was placed in a dialysis bag with a molecular weight cut-off of 3500Da, and dialyzed with deionized water for 48h, and then freeze-dried to obtain amido carbon quantum dots;

[0061] 4. The polyimide resin with a molecular weight of 1500Da and the medium temperature pitch were respectively melted at 110℃, and then mixed with the amido carbon quantum dots and DL-411-A at 80℃ for 30min; the mass ratio of the polyimide resin, the medium temperature pitch, the amido carbon quantum dots and the aluminate coupling agent was 40:60:2:1.5, to obtain a composite binder; TiB2nanoparticles, anhydrous ethanol and boric acid were mixed in a mass ratio of 3:4:8 to obtain a composite antioxidant;

[0062] 5. Silicon powder and formaldehyde were mixed in a mass ratio of 1:4, and then adjusted to pH=8 with an ammonia chloride buffer solution (ammonia water and ammonium chloride in a mass ratio of 3:1); the mixture was stirred at 500rpm for 60min to obtain carbon-coated silicon powder;

[0063] 6. The carbon-coated modified aggregate, the modified flake graphite powder, the nanocarbon spheres and the composite binder were blended and kneaded at 145℃ and 80rpm for 30min, and then the composite antioxidant and the carbon-coated silicon powder were added; the mixture was cured at 180℃ and a vacuum degree of-0.09MPa for 1h, and then the hydrophobic fumed silica was added and mixed at 110℃ for 15min; the mass ratio of the carbon-coated modified aggregate, the modified flake graphite powder, the nanocarbon spheres, the composite binder, the composite antioxidant, the carbon-coated silicon powder and the hydrophobic fumed silica was 100:30:5:100:4:4:0.5, to obtain electrode paste slurry; the electrode paste slurry was pressed in a mold at a pressure of 3MPa for 2min, at a pressure of 10MPa for 5min and at a pressure of 30MPa for 10min, and then demolded at 80℃ after molding at 140℃, to obtain an electrode paste body;

[0064] 7. The electrode paste body was pre-carbonized at 280℃ in a nitrogen atmosphere for 1.5h, to obtain the high-density corrosion-resistant electrode paste.

[0065] Performance test:

[0066] The high-density corrosion-resistant electrode paste prepared in Example 2 was subjected to the following corrosion resistance test:

[0067] Acid resistance: soak in 5% sulfuric acid at room temperature for 72h, weigh before and after, calculate the mass loss rate, record the appearance change; another electrode paste sample is soaked in 30% hydrochloric acid at 60℃ for 48h, weigh before and after, calculate the mass loss rate, record the appearance change;

[0068] Alkali resistance: soak in 10% sodium hydroxide at room temperature for 72h, weigh before and after, calculate the mass loss rate, record the appearance change; another electrode paste sample is soaked in 40% potassium hydroxide at 80℃ for 48h, weigh before and after, calculate the mass loss rate, record the appearance change;

[0069] Salt resistance: soak in 10% sodium chloride at room temperature for 168h, weigh before and after, calculate the mass loss rate, record the appearance change;

[0070] Organic solvent resistance: soak in toluene at room temperature for 168h, weigh before and after, calculate the mass loss rate, record the appearance change;

[0071] The above test results are shown in Table 2.

[0072] Table 2 Test results of corrosion resistance of Example 2

[0073]

[0074] Example 3

[0075] A method for preparing a high-density corrosion-resistant electrode paste, comprising the following steps:

[0076] 1. Mix the anthracite and petroleum coke in a mass ratio of 6:3, then place them in a plasma etching device, introduce Ar gas, set the power to 500W, and etch for 5min to obtain mixed aggregate. The mixed aggregate is immersed in a carbon nanotube dispersion liquid containing 3wt% carbon nanotubes and 1wt% sodium dodecylbenzenesulfonate, ultrasonically treated for 10min, and then stirred at 100r / min for 10min to obtain carbon-coated modified aggregate;

[0077] 2. High-speed shear the flake graphite powder at 3000r / min for 10min, immerse it in an ethanol aqueous solution containing 5% KH-560, the mass of KH-560 is 0.5% of the mass of the flake graphite powder, react at 80℃ for 3h, and then continue to react at 120℃ under nitrogen atmosphere for 1h to obtain modified flake graphite powder;

[0078] 3. The carboxylated carbon quantum dot solution with a concentration of 20 wt%, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide were mixed, and then ethylenediamine was added dropwise under a nitrogen atmosphere; the mass-volume ratio of the carboxylated carbon quantum dot solution, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, N-hydroxysuccinimide and ethylenediamine was 50 mL:2 g:1.2 g:3 mL; the reaction was carried out at 60°C for 4 h; after the reaction was completed, the reaction system was placed in a dialysis bag with a molecular weight cut-off of 4000 Da, and dialyzed with deionized water for 72 h, and then freeze-dried to obtain amido carbon quantum dots;

[0079] 4. The polyimide resin with a molecular weight of 3500 Da and the medium temperature pitch were separately melted at 120°C, and then mixed with the amido carbon quantum dots and DL-411-A at 90°C for 60 min; the mass ratio of the polyimide resin, the medium temperature pitch, the amido carbon quantum dots and the aluminate coupling agent was 40:60:2.2:1.5, to obtain a composite binder; TiB2 nanoparticles, anhydrous ethanol and boric acid were mixed in a mass ratio of 3:4:10 to obtain a composite antioxidant;

[0080] 5. Silicon powder and formaldehyde were mixed in a mass ratio of 1:5, and then adjusted to pH=9 with an ammonia chloride buffer solution (ammonia water and ammonium chloride in a mass ratio of 3:1); the mixture was stirred at 800 rpm for 90 min to obtain carbon-coated silicon powder;

[0081] 6. The carbon-coated modified aggregate, the modified flake graphite powder, the nanocarbon spheres and the composite binder were blended and kneaded at 155°C and 80 rpm for 40 min, and then the composite antioxidant and the carbon-coated silicon powder were added; the mixture was cured at 180°C and a vacuum degree of -0.09 MPa for 1 h, and then the hydrophobic fumed silica was added and mixed at 110°C for 15 min; the mass ratio of the carbon-coated modified aggregate, the modified flake graphite powder, the nanocarbon spheres, the composite binder, the composite antioxidant, the carbon-coated silicon powder and the hydrophobic fumed silica was 100:30:5:105:5:4:0.5, to obtain electrode paste slurry; the electrode paste slurry was pressed in a mold at a pressure of 3 MPa for 2 min, at a pressure of 10 MPa for 5 min and at a pressure of 30 MPa for 10 min, and then molded at 140°C; the electrode paste green body was demolded at 80°C.

[0082] 7. The electrode paste green body was pre-carbonized at 300°C in a nitrogen atmosphere for 2 h to obtain the high-density corrosion-resistant electrode paste.

[0083] Performance test:

[0084] The high-density corrosion-resistant electrode paste prepared in Example 3 was subjected to the following corrosion resistance test:

[0085] Acid resistance: soak in 5% sulfuric acid at room temperature for 72h, weigh before and after, calculate the mass loss rate, record the appearance change; another electrode paste sample is soaked in 30% hydrochloric acid at 60°C for 48h, weigh before and after, calculate the mass loss rate, record the appearance change;

[0086] Alkali resistance: soak in 10% sodium hydroxide at room temperature for 72h, weigh before and after, calculate the mass loss rate, record the appearance change; another electrode paste sample is soaked in 40% potassium hydroxide at 80°C for 48h, weigh before and after, calculate the mass loss rate, record the appearance change;

[0087] Salt resistance: soak in 10% sodium chloride at room temperature for 168h, weigh before and after, calculate the mass loss rate, record the appearance change;

[0088] Organic solvent resistance: soak in toluene at room temperature for 168h, weigh before and after, calculate the mass loss rate, record the appearance change;

[0089] The above test results are shown in Table 3.

[0090] Table 3 Test results of corrosion resistance of Example 3

[0091]

[0092] Comparative Example 1

[0093] A method for preparing a high-density corrosion-resistant electrode paste, the preparation method and parameters are the same as those of Example 1, the difference is that untreated anthracite and petroleum coke are directly used.

[0094] Performance test:

[0095] The high-density corrosion-resistant electrode paste prepared in Comparative Example 1 of the present application was subjected to the following corrosion resistance test:

[0096] Acid resistance: soak in 5% sulfuric acid at room temperature for 72h, weigh before and after, calculate the mass loss rate, record the appearance change; another electrode paste sample is soaked in 30% hydrochloric acid at 60°C for 48h, weigh before and after, calculate the mass loss rate, record the appearance change;

[0097] Alkali resistance: soak in 10% sodium hydroxide at room temperature for 72h, weigh before and after, calculate the mass loss rate, record the appearance change; another electrode paste sample is soaked in 40% potassium hydroxide at 80°C for 48h, weigh before and after, calculate the mass loss rate, record the appearance change; Figure 1

[0098] Salt resistance: soak in 10% sodium chloride at room temperature for 168h, weigh before and after, calculate the mass loss rate, record the appearance change;

[0099] ​Resistance to organic solvents: soak in toluene at room temperature for 168 h, weigh before and after, calculate the mass loss rate, and record the appearance change;

[0100] The test results are shown in Table 4.

[0101] Table 4 Test results of corrosion resistance of Comparative Example 1

[0102]

[0103] Comparative Example 2

[0104] A method for preparing a high-density corrosion-resistant electrode paste, the preparation method and parameters are the same as those of Example 1, the difference is that carboxylated carbon quantum dots are directly used instead of amido carbon quantum dots.

[0105] Performance test:

[0106] The high-density corrosion-resistant electrode paste prepared in Comparative Example 2 of the present application was subjected to the following corrosion resistance test:

[0107] Resistance to acid: soak in 5% sulfuric acid at room temperature for 72 h, weigh before and after, calculate the mass loss rate, and record the appearance change; another electrode paste sample was soaked in 30% hydrochloric acid at 60°C for 48 h, weighed before and after, calculated the mass loss rate, and recorded the appearance change;

[0108] Resistance to alkali: soak in 10% sodium hydroxide at room temperature for 72 h, weigh before and after, calculate the mass loss rate, and record the appearance change; another electrode paste sample was soaked in 40% potassium hydroxide at 80°C for 48 h, weighed before and after, calculated the mass loss rate, and recorded the appearance change;

[0109] Resistance to salt: soak in 10% sodium chloride at room temperature for 168 h, weigh before and after, calculate the mass loss rate, and record the appearance change;

[0110] Resistance to organic solvents: soak in toluene at room temperature for 168 h, weigh before and after, calculate the mass loss rate, and record the appearance change;

[0111] The test results are shown in Table 5.

[0112] Table 5 Test results of corrosion resistance of Comparative Example 2

[0113]

[0114] Comparative Example 3

[0115] A method for preparing a high-density corrosion-resistant electrode paste, the preparation method and parameters are the same as those of Example 1, the difference is that silicon powder is directly used instead of carbon-coated silicon powder.

[0116] Performance test:

[0117] The high-density corrosion-resistant electrode paste prepared in Comparative Example 3 of the present application was subjected to the following corrosion resistance tests:

[0118] Acid resistance: immerse in 5% sulfuric acid at room temperature for 72 h, weigh before and after, calculate the mass loss rate, and record the appearance change; another electrode paste sample was immersed in 30% hydrochloric acid at 60°C for 48 h, weighed before and after, calculated the mass loss rate, and recorded the appearance change;

[0119] Alkali resistance: immerse in 10% sodium hydroxide at room temperature for 72 h, weigh before and after, calculate the mass loss rate, and record the appearance change; another electrode paste sample was immersed in 40% potassium hydroxide at 80°C for 48 h, weighed before and after, calculated the mass loss rate, and recorded the appearance change;

[0120] Salt resistance: immerse in 10% sodium chloride at room temperature for 168 h, weigh before and after, calculate the mass loss rate, and record the appearance change;

[0121] Organic solvent resistance: immerse in toluene at room temperature for 168 h, weigh before and after, calculate the mass loss rate, and record the appearance change;

[0122] The test results are shown in Table 6.

[0123] Table 6 Test results of corrosion resistance of Comparative Example 3

[0124]

[0125] Density test:

[0126] The volume density of the high-density corrosion-resistant electrode paste prepared in Examples 1-3 and Comparative Examples 1-3 was tested, and the results are shown in Table 7.

[0127] Table 7 Density test results of Examples 1-3 and Comparative Examples 1-3

[0128]

[0129] From Tables 1-7, Figure 1 It can be seen that the mass loss rate of the high-density corrosion-resistant electrode paste prepared in Examples 1-3 of the present application before and after the test is in the range of 0.08%-3.61%, and the volume density is 1.66-1.70 g / cm 3 The mass loss rate of Comparative Examples 1-3 is 0.47%-5.51%, and the volume density is 1.40-1.52 g / cm 3 , which shows that the product prepared in the examples has better corrosion resistance and density compared with the comparative examples.

[0130] Comparative Example 1 does not perform plasma etching and carbon nanotube coating on anthracite and petroleum coke, so the aggregate surface lacks oxygen-containing functional groups and conductive network, the binder wettability decreases, and the porosity increases. The corrosive medium can easily penetrate through the pores, resulting in a significant increase in mass loss rate compared to Example 1, especially under high-temperature strong corrosion conditions (30% hydrochloric acid at 60°C, 40% potassium hydroxide at 80°C), the corrosion resistance is worse.

[0131] Comparative Example 2 carboxylated carbon quantum dots are not modified with amide groups, and the π-π conjugation with polyimide is weakened, the binder cohesion decreases, and the interfacial bonding force decreases. In a high-temperature corrosion environment, the binder and aggregate interface is prone to peeling, resulting in a higher mass loss rate than Example 1, but due to the presence of physical dispersion, the performance is better than Comparative Example 1.

[0132] Comparative Example 3 does not coat carbon-silicon powder, which expands in volume during testing due to high temperature or corrosion environment, damaging the overall structure of the electrode paste and causing cracks and porosity. The mass loss rate is higher than Example 1, and the appearance shows obvious structural damage, especially under long-term immersion and high-temperature conditions, the structural damage causes the corrosion medium to penetrate faster.

[0133] The above results show and describe the basic principles and main features of the present application and the advantages of the present application.

[0134] Those skilled in the art should understand that the present application is not limited by the above examples, the above examples and descriptions in the specification are only to illustrate the principles of the present application, and various changes and improvements can be made without departing from the spirit and scope of the present application, these changes and improvements all fall within the scope of the claimed application. The scope of protection claimed by the present application is defined by the equivalents of the appended claims.

Claims

1. A method for preparing a high-density corrosion-resistant electrode paste, characterized by, The method comprises the following steps: S1, pretreating anthracite and petroleum coke to obtain mixed aggregate, coating carbon nanotubes on the surface of the mixed aggregate to obtain carbon-coated modified aggregate; S1, pretreating anthracite and petroleum coke to obtain mixed aggregate, coating carbon nanotubes on the surface of the mixed aggregate to obtain carbon-coated modified aggregate; S2, mixing carboxylated carbon quantum dot solution, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide, adding ethylenediamine dropwise under a nitrogen atmosphere, reacting at a first set temperature, and dialyzing to obtain amido carbon quantum dots; S3, melting polyimide resin and medium-temperature pitch at a second set temperature, mixing the amido carbon quantum dots and aluminic ester coupling agent at a third set temperature to obtain a composite binder, mixing TiB2 nanoparticles and boric acid to obtain a composite antioxidant, and stirring and reacting silicon powder and formaldehyde at a set pH to obtain carbon-coated silicon powder; S4, blending and kneading the carbon-coated modified aggregate, modified flake graphite powder, nanometer carbon balls and the composite binder, adding the composite antioxidant and the carbon-coated silicon powder, aging, adding hydrophobic fumed silica, and mixing at a fourth set temperature to obtain electrode paste slurry; pressing the electrode paste slurry under a gradient pressure, demolding after shaping to obtain an electrode paste blank; and performing pre-carbonization treatment on the electrode paste blank in a nitrogen atmosphere to obtain the high-density corrosion-resistant electrode paste.

2. The method for preparing a high-density corrosion-resistant electrode paste according to claim 1, characterized in that, The particle size of the anthracite in S1 is 3-8 mm, the particle size of the petroleum coke is 0.5-3 mm, and the mass ratio of the anthracite to the petroleum coke is 6:(2.5-3); the pretreatment is Ar plasma etching for 5 min; the specific method for coating carbon nanotubes is: immersing the mixed aggregate in a carbon nanotube dispersion liquid, ultrasonic stirring for 20 min, and filtering and drying; the carbon nanotube dispersion liquid contains 2wt%-3wt% carbon nanotubes and 0.8wt%-1wt% sodium dodecylbenzenesulfonate.

3. The method for preparing a high-density corrosion-resistant electrode paste according to claim 1, characterized in that, The particle size of the flake graphite powder in S1 is 5-20 μm, the silane modification treatment uses an ethanol aqueous solution of KH-560 with a concentration of 5%, the mass of the KH-560 is 0.3%-0.5% of the mass of the flake graphite powder, and the silane modification treatment is 80℃ for 2-3 h, followed by 120℃ for 1 h under a nitrogen atmosphere.

4. The method for preparing a high-density corrosion-resistant electrode paste according to claim 1, characterized in that, The concentration of the carboxylated carbon quantum dot solution in S2 is 15wt%-20wt%, and the mass-volume ratio of the carboxylated carbon quantum dot solution, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, N-hydroxysuccinimide and ethylenediamine is 50mL:(1.8-2)g:(1-1.2)g:3mL.

5. The method for preparing a high-density corrosion-resistant electrode paste according to claim 1, characterized in that, The first set temperature in S2 is 60℃, and the reaction time at the first set temperature is 3-4 h; the molecular weight cut off during dialysis is 3500-4000 Da, and the dialysis time is 48-72 h.

6. The method for preparing a high-density corrosion-resistant electrode paste according to claim 1, characterized in that, S3 the second set temperature is 110-120℃, the third set temperature is 80-90℃, the mixing time at the third set temperature is 30-60min; the mass ratio of the polyimide resin, the medium temperature pitch, the amido carbon quantum dot and the aluminate coupling agent is 40:60:(2-2.2):1.5; the molecular weight of the polyimide resin is 1500-3500Da; the aluminate coupling agent is DL-411-A.

7. The method for preparing a high-density corrosion-resistant electrode paste according to claim 1, characterized in that, S3 the mass ratio of the TiB2 nanoparticles and boric acid is 3:(8-10), the particle size of the TiB2 nanoparticles is 50-100nm; the mass ratio of the silicon powder and formaldehyde is 1:(4-5); the particle size of the silicon powder is 2-8μm; the set pH is 8-9, the stirring time is 60-90min, the stirring speed is 500-800rpm.

8. The method for preparing a high-density corrosion-resistant electrode paste according to claim 1, characterized in that, S4 the mass ratio of the carbon-coated modified aggregate, the modified flake graphite powder, the nanometer carbon sphere, the composite binder, the composite antioxidant, the carbon-silicon powder and the hydrophobic fumed silica is 100:30:5:(100-105):(4-5):4:0.5; the blending and kneading temperature is 145-155℃, the rotation speed is 80rpm, the time is 30-40min; the curing is carried out at 180℃, vacuum degree-0.09MPa, the curing time is 1h, the fourth set temperature is 110℃, the mixing time at the fourth set temperature is 15min.

9. The method for preparing a high-density corrosion-resistant electrode paste according to claim 1, characterized in that, S4 the gradient pressure includes: 3MPa pressure for 2min; 10MPa pressure for 5min; 30MPa pressure for 10min; the molding temperature is 140℃, the demolding temperature is 80℃; the pre-carbonization treatment temperature is 280-300℃, the time is 1.5-2h.

10. A high-density corrosion-resistant electrode paste prepared by the preparation method of any one of claims 1-9.

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