Flowable conductive zinc paste, method of making and hydrogen production applications thereof

Abstract

The present application relates to a kind of flowable conductive zinc slurry and its preparation method and hydrogen production application, and the conductive zinc slurry includes zinc salt aqueous solution, conductive agent, dispersant and organic ligand, the mass ratio of zinc salt aqueous solution, conductive agent, dispersant and organic ligand is (50-280) :(10-60) :(5-50) :(5-40), the conductive zinc slurry is used as cathode slurry electrode liquid, for two-step hydrogen production.Compared with prior art, the present application provides a kind of efficient, safe, low-cost cycle process route to realize electrochemical efficient step-by-step water splitting hydrogen production, the coulomb efficiency of hydrogen production reaches more than 98%, while oxygen and zinc metal by-products can be obtained, and it has very high application value in the field of electrochemical water splitting hydrogen production technology.

Description

Technical Field

[0001] This invention relates to the field of electrochemical water splitting for hydrogen production, and in particular to a flowable conductive zinc slurry, its preparation method, and its application in hydrogen production. Background Technology

[0002] In 2023, my country's total hydrogen production was approximately 35.5 million tons, making it the world's largest hydrogen energy producer. Among various hydrogen production methods, water electrolysis offers advantages such as zero carbon emissions, high product purity, and strong storage capacity for intermittent renewable energy. Therefore, it is foreseeable that fossil fuel-based hydrogen production will gradually be replaced by renewable energy-based hydrogen production, forming a zero-carbon industrial chain of new energy power generation – water electrolysis for hydrogen production. Currently, the key bottleneck restricting the development of water electrolysis hydrogen production technology lies in the energy loss caused by the high overpotential of the hydrogen evolution reaction (HER) at the cathode, resulting in an energy efficiency of only 20-70%. On the other hand, the hydrogen and oxygen generated by water electrolysis can cross-contaminate between the cathode and anode of the electrolyzer through porous membranes, thereby reducing the Faraday efficiency of the electrolyzer and even causing explosions due to gas cross-contamination. Proton exchange membranes can suppress cross-contamination between the cathode and anode by conducting protons, but they are very expensive.

[0003] Zinc metal has a higher chemical reactivity than hydrogen, and hydrogen can be produced through a displacement reaction with inorganic acid solutions, achieving 100% reaction completion. On the other hand, zinc metal, currently widely studied as the negative electrode for rechargeable secondary batteries, can be reversibly deposited in weakly acidic aqueous electrolytes. However, direct charging on the electrode plate leads to dendritic electroplating of the deposited zinc, which eventually breaks off to form dead zinc. Additionally, parasitic side reactions related to zinc species can occur, all of which affect the yield and purity of the electrodeposited zinc. Summary of the Invention

[0004] The purpose of this invention is to provide a flowable conductive zinc paste, its preparation method, and its hydrogen production application, effectively avoiding the formation of zinc dendrites during electroplating.

[0005] The objective of this invention can be achieved through the following technical solution: a flowable conductive zinc slurry, comprising a zinc salt aqueous solution, a conductive agent, a dispersant and an organic ligand, wherein the mass ratio of the zinc salt aqueous solution, the conductive agent, the dispersant and the organic ligand is (50-280):(10-60):(5-50):(5-40).

[0006] Preferably, the zinc salt aqueous solution is one or a combination of two or more of the following: zinc sulfate aqueous solution, zinc chloride aqueous solution, zinc sulfide aqueous solution, zinc perchlorate aqueous solution, zinc trifluoromethanesulfonate aqueous solution, zinc nitrate aqueous solution, and zinc acetate aqueous solution.

[0007] Preferably, the conductive agent is one or a combination of two or more of conductive carbon black, Ketjen black, acetylene black, Cabot carbon black, carbon nanotubes, and graphene.

[0008] Preferably, the dispersant is one or a combination of two or more of the following: polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, carboxymethyl cellulose, polyethylene oxide, polyacrylamide, and polyacrylic acid.

[0009] Preferably, the organic ligand is one or a combination of two or more of the following: cysteine, cystine, glutamic acid, glycine, methionine, mercaptoacetic acid, mercaptopropionic acid, mercaptobutyric acid, mercaptoethanol, mercaptopropanol, mercaptobutanol, glutathione, mercaptoethylamine, mercaptopropylamine, and mercaptobutylamine.

[0010] A method for preparing the above-mentioned flowable conductive zinc paste includes the following steps:

[0011] S1. Weigh 10-60 parts by weight of conductive agent, 5-50 parts by weight of dispersant, 5-40 parts by weight of organic ligand, 20-80 parts by weight of zinc salt, and 30-200 parts by weight of water, and mechanically stir until uniformly mixed to obtain a preliminary mixed dispersion.

[0012] S2. Transfer the preliminary mixed dispersion obtained in step S1 to a ball mill jar and ball mill at a speed of 100-1000 rpm for 2-48 hours to obtain a uniformly mixed conductive zinc slurry.

[0013] An application of the above-mentioned flowable conductive zinc slurry in hydrogen production involves using the conductive zinc slurry as a cathode slurry electrode liquid for a two-step hydrogen production process.

[0014] Preferably, the hydrogen production application of the flowable conductive zinc slurry includes the following steps: the first step is to use the conductive zinc slurry as the cathode slurry electrode liquid and send it into an electrolytic cell for electrolysis to obtain electrodeposited zinc nanoparticles, while simultaneously collecting oxygen byproducts at the anode;

[0015] The second step involves introducing the electrodeposited zinc nanoparticles into an inorganic acid solution for reaction, producing hydrogen gas which is then collected.

[0016] More preferably, the hydrogen production application of the flowable conductive zinc paste specifically includes the following steps:

[0017] (1) Use the conductive zinc paste as the cathode paste electrode liquid, at a concentration of 1-100 mL·min -1 The flow rate is pumped into the cathode electrolytic cell and circulated back to the cathode tank. The anolyte is pumped into the anolyte electrolytic cell, and the anolyte is inserted into the cathode electrolytic cell with an area of ​​2-30 cm². 2 The conductive current collector is inserted into the anodic electrolytic cell with a surface coating of 0.5-10 mg / cm². 2The conductive current collector for the oxygen evolution catalyst has a solid diaphragm inserted between the two electrodes and then operates at 10-1000 mA / cm. 2 Electrolysis is carried out at a current density for 0.5-15 hours to obtain electrodeposited zinc slurry products in the cathode electrolytic cell, while oxygen is obtained by electrolysis in the anodic electrolytic cell and collected.

[0018] (2) Vacuum filter the electrodeposited zinc slurry product to obtain the electrodeposited zinc nanoparticle-conductive agent composite and filtrate. Add 50-200 parts by weight of inorganic acid and 20-120 parts by weight of water to the electrodeposited zinc nanoparticle-conductive agent composite, stir until uniformly mixed, collect the hydrogen gas produced by the reaction, and obtain the reaction cathode residual slurry.

[0019] In this invention, the zinc nanoparticle-conductive agent composite formed by electrodeposition forms a conductive network composite in the zinc slurry system in a mutually bridging manner. The zinc nanoparticles and the conductive agent network are combined by one or more of the following: van der Waals forces, electrostatic forces, and ionic bonds.

[0020] More preferably, the anolyte in step (1) is an aqueous solution of zinc salt.

[0021] More preferably, the conductive current collector in step (1) is one or a combination of two or more of the following: stainless steel mesh, carbon cloth, carbon paper, carbon felt, copper foil, and aluminum foil.

[0022] More preferably, the solid membrane in step (1) is one or a combination of two or more of the following: polyethylene membrane, polypropylene membrane, filter paper, Asahi Kasei membrane, Tonen membrane, NKK membrane, ENTEK membrane, and Celgard membrane.

[0023] More preferably, the oxygen evolution catalyst in step (1) is one or a combination of two or more of platinum oxide, ruthenium oxide, palladium oxide, iridium oxide, manganese oxide, cobalt oxide, cobalt titanate, and graphene.

[0024] More preferably, the inorganic acid in step (2) is one or a combination of two or more of sulfuric acid, hydrochloric acid, hydrofluoric acid, perchloric acid, trifluoromethanesulfonic acid, nitric acid, and acetic acid.

[0025] More preferably, the application of the flowable conductive zinc paste further includes the following steps:

[0026] (3) Mix the filtrate from step (2) with the residual slurry from the reaction cathode and stir mechanically until homogeneous to obtain the slurry to be regenerated;

[0027] (4) While stirring, add 5-30 parts by weight of water to the slurry to be regenerated in step (3), and then add 1-10 parts by weight of solid alkali to adjust the pH of the slurry to between 3 and 7 to obtain the slurry mother liquor to be regenerated.

[0028] (5) Transfer the mother liquor of the slurry to be regenerated obtained in step (4) to a ball milling jar and ball mill at a speed of 100-1000 rpm for 2-48 hours to obtain the regenerated conductive zinc slurry.

[0029] Preferably, the solid alkali in step (4) is one or a combination of two or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium bicarbonate, sodium carbonate, calcium hydroxide, and barium hydroxide.

[0030] A method for preparing and electrolyzing the above-mentioned conductive zinc paste includes the following steps:

[0031] S1. Weigh 10-60 parts by weight of conductive agent, 5-50 parts by weight of dispersant, 5-40 parts by weight of organic ligand, 20-80 parts by weight of zinc salt, and 30-200 parts by weight of water, and mechanically stir until uniformly mixed to obtain a preliminary mixed dispersion.

[0032] S2. Transfer the preliminary mixed dispersion obtained in step S1 to a ball mill jar and ball mill at a speed of 100-1000 rpm for 2-48 hours to obtain a uniformly mixed cathode slurry electrode liquid.

[0033] S3. Weigh 20-80 parts by weight of zinc salt and 30-200 parts by weight of water, and mechanically stir until completely dissolved to obtain a uniformly mixed anolyte.

[0034] S4. Dissolve the cathode slurry electrode liquid obtained in step S2 at a rate of 1-100 mL / min. -1 The flow rate is pumped into the cathode electrolytic cell and circulated back to the cathode tank. The anolyte obtained in step S3 is pumped into the anolyte electrolytic cell, and inserted into the cathode electrolytic cell with an area of ​​2-30 cm². 2 A conductive current collector is inserted into the anolyte of an anolyte coated with an oxygen evolution catalyst (0.5-10 mg / cm³). 2 A conductive current collector is used, with a solid diaphragm inserted between the two electrodes, and then the current is applied at a rate of 10-1000 mA / cm. 2 Electrolysis is carried out at a current density for 0.5-15 hours. Electrodeposited zinc slurry is obtained in the cathode electrolytic cell, while oxygen is obtained by electrolysis in the anode electrolytic cell and collected by water displacement.

[0035] Preferably, the conductive agent in step S1 is one or a combination of two or more of conductive carbon black, Ketjen black, acetylene black, Cabot carbon black, carbon nanotubes, and graphene.

[0036] Preferably, the dispersant in step S1 is one or a combination of two or more of the following: polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, carboxymethyl cellulose, polyethylene oxide, polyacrylamide, and polyacrylic acid.

[0037] Preferably, the zinc salt in step S1 is one or a combination of two or more of zinc sulfate, zinc chloride, zinc sulfide, zinc perchlorate, zinc trifluoromethanesulfonate, zinc nitrate, and zinc acetate.

[0038] Preferably, the organic ligand in step S1 is one or a combination of two or more of the following: cysteine, cystine, glutamic acid, glycine, methionine, mercaptoacetic acid, mercaptopropionic acid, mercaptobutyric acid, mercaptoethanol, mercaptopropanol, mercaptobutanol, glutathione, mercaptoethylamine, mercaptopropylamine, and mercaptobutylamine.

[0039] Preferably, the conductive current collector in step S4 is one or a combination of two or more of the following: stainless steel mesh, carbon cloth, carbon paper, carbon felt, copper foil, and aluminum foil.

[0040] Preferably, the solid membrane in step S4 is one or a combination of two or more of the following: polyethylene membrane, polypropylene membrane, filter paper, Asahi Kasei membrane, Tonen membrane, NKK membrane, ENTEK membrane, and Celgard membrane.

[0041] Preferably, the oxygen evolution catalyst in step S4 is one or a combination of two or more of platinum oxide, ruthenium oxide, palladium oxide, iridium oxide, manganese oxide, cobalt oxide, cobalt titanate, and graphene.

[0042] A method for chemical hydrogen production using the zinc slurry solid filter material after electrodeposition as described above includes the following steps:

[0043] S5. Vacuum filter the zinc slurry product obtained after electrolysis in the cathode tank in step S4 above to obtain zinc slurry solid filter material and filtrate.

[0044] S6. Collect the electrode solution after the reaction in the anode tank in step S4 above to obtain the anode residue;

[0045] S7. Add 50-200 parts by weight of inorganic acid and 20-120 parts by weight of water to the zinc slurry solid filter material from step S5, stir until uniformly mixed, and collect the hydrogen gas produced by the reaction using a gas cylinder to obtain the residual slurry of the reaction cathode.

[0046] Preferably, the inorganic acid in step S7 is one or a combination of two or more of sulfuric acid, hydrochloric acid, hydrofluoric acid, perchloric acid, trifluoromethanesulfonic acid, nitric acid, and acetic acid.

[0047] A method for preparing a recyclable, regenerated cathode flowable conductive zinc slurry system and an anode electrolyte includes the following steps:

[0048] S8. Mix the filtrate from step S5 and the reaction residue slurry from step S7, and mechanically stir until uniform to obtain the mother liquor of the slurry to be regenerated.

[0049] S9. While stirring, add 5-30 parts by weight of water to the mother liquor of the slurry to be regenerated in step S8, and then add 1-10 parts by weight of solid alkali to adjust the pH of the slurry to between 3 and 7 to obtain the mother liquor of the slurry to be regenerated.

[0050] S10. Transfer the mother liquor of the slurry to be regenerated obtained in step S9 to a ball mill jar and ball mill at a speed of 100-1000 rpm for 2-48 hours to obtain a regenerated flowable conductive zinc slurry system that can be used for the electrolytic reaction in the next step S4.

[0051] S11. Weigh 5-50 parts by weight of water and 1-10 parts by weight of solid alkali and add them to the anolyte from step S6. Stir mechanically until the mixture is homogeneous. Adjust the pH of the anolyte to between 3 and 7 to obtain a regenerated anolyte, which can be used for the electrolysis reaction in the next step S4.

[0052] Preferably, the solid alkali mentioned in steps S9 and S11 is one or a combination of two or more of lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium bicarbonate, sodium carbonate, calcium hydroxide, and barium hydroxide.

[0053] This invention discloses a circulating process for a two-step hydrogen production using a flow-through zinc slurry electrolytic cell system. First, a semi-solid slurry prepared with a conductive agent, dispersant, organic ligand, and zinc salt aqueous solution is used as the cathode electrode solution. In the first step, this electrode solution is pumped into the electrolytic cell at a certain flow rate for electrolysis to obtain monodisperse electrodeposited zinc nanoparticles, while simultaneously collecting oxygen byproducts at the anode. In the second step, the solid product after filtration of the electrodeposited zinc slurry is introduced into an inorganic acid solution for complete reaction to produce hydrogen, which is then collected. Finally, alkaline solution is introduced into the reaction residues at the cathode and anode to adjust the pH, and water is introduced to adjust the ion concentration. After thorough mixing, the mixture is returned to the electrolytic cell for recycling. The organic ligand prevents excessive growth and aggregation of zinc species during electrodeposition, instead electrodepositing them as monodisperse nanoparticles within the conductive network of the slurry system. This invention provides a highly efficient, safe, and low-cost cyclic process route for electrochemically efficient stepwise water splitting to produce hydrogen, achieving a coulombic efficiency of over 98% while simultaneously obtaining oxygen and zinc metal byproducts. This invention has high application value in the field of electrochemical water splitting for hydrogen production.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] 1. The flowable conductive zinc slurry system of this invention consists of a zinc salt aqueous solution, a conductive agent, a dispersant, and an organic ligand. After electrodeposition, the resulting zinc nanoparticle-conductive agent composite forms a conductive network complex within the zinc slurry system through mutual bridging, combining one or more of van der Waals forces, electrostatic forces, and ionic bonds. Testing revealed that charging and discharging this zinc slurry system enables reversible and efficient zinc electrodeposition, avoiding the formation of zinc dendrites. Simultaneously, the hydrogen bonding regulation effect of the organic ligand effectively mitigates water decomposition and parasitic side reactions such as basic zinc sulfate during the electrodeposition process. Testing showed that the zinc plating coulombic efficiency reached as high as 99.6%. Combined with the 100% reaction completion rate of zinc metal with inorganic acid in the second step, this indicates that the cyclic technology route of this invention can achieve an electrochemical hydrogen production efficiency exceeding 98%, far superior to traditional electrocatalytic water splitting hydrogen production processes.

[0056] 2. This invention optimizes the traditional one-step method of directly electrolyzing aqueous solutions to obtain hydrogen and oxygen at the anode and cathode respectively into a method where the zinc species are first reduced in the first step, and then the hydrogen ions are reduced by zinc metal particles in the second step to release hydrogen. This effectively solves the explosion risk caused by gas crosstalk between the cathode and anode in the traditional water electrolysis process. In addition, it simplifies the difficulties of alkaline water electrolysis cells, such as the need for additional heating and the difficulty in quickly adjusting the hydrogen production rate.

[0057] 3. This invention overcomes the shortcomings of existing electrolytic cells composed of aqueous electrolytes and zinc metal plate electrodes. For the first time, it uses zinc salt aqueous solution, conductive agent, dispersant, and organic ligands to create a flowable conductive zinc slurry electrode system, replacing the traditional fixed zinc metal plate electrode model. In the recycling technology route, a process scheme capable of regenerating both the cathode slurry and anode electrode liquid is designed, enabling the cyclical production of hydrogen, oxygen, and zinc metal byproducts solely through the consumption of electricity generated from renewable energy sources and inexpensive industrial products (water, inorganic acids, solid alkalis, etc.).

[0058] 4. The preparation process of this invention is efficient, safe, environmentally friendly, and simple to operate. It avoids the use of expensive proton exchange membranes, is low in cost, and can easily achieve large-scale, high-efficiency hydrogen production without excessive energy consumption, thereby significantly increasing hydrogen energy production capacity.

[0059] 5. This invention overcomes the shortcomings of existing technologies in the electrochemical water splitting for hydrogen production, such as the scarcity and high price of hydrogen evolution catalysts, low energy efficiency of water splitting, and the risk of explosion caused by gas cross-contamination.

[0060] 6. This invention provides a method for preparing a flowable conductive zinc slurry and its hydrogen production application. The slurry can be regenerated for recycling and effectively avoids the formation of zinc dendrites during electroplating. Attached Figure Description

[0061] Figure 1 This is a structural and process flow diagram of a flowable zinc slurry electrolytic cell system.

[0062] Figure 2 A schematic diagram of the two-step hydrogen production cycle in a flow-through zinc slurry electrolytic cell system.

[0063] Figure 3 The precipitation curves of a flow-through zinc slurry electrolytic cell system at different ligand concentrations are shown.

[0064] Figure 4 (a) is a wide-view transmission electron microscope (TEM) image of the zinc paste product obtained after electrodeposition; (b) is a high-resolution TEM image of a portion of the zinc paste product after electrodeposition.

[0065] Figure 5 The image shows a scanning electron microscope (SEM) image of the zinc plate-like product obtained after electrodeposition. The inset in the lower right corner shows the corresponding zinc elemental surface scan.

[0066] Figure 6 XRD images of zinc paste and zinc plate products obtained after electrodeposition.

[0067] Figure 7 (a) shows the polarization curves and corresponding coulombic efficiency evolution trends of the circulating stripping deposition flow zinc slurry system; (b) shows the polarization curves and corresponding coulombic efficiency evolution trends of the circulating stripping deposition zinc plate system. Detailed Implementation

[0068] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0069] Unless otherwise specified, the reagents, methods, instruments, and equipment used in this invention are conventional in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0070] Example 1

[0071] This embodiment provides a method for preparing and electrolyzing a flowable conductive zinc slurry system, including the following steps:

[0072] (1) Preparation of cathode electrode slurry: Weigh 20g of Cabot carbon black, 12g of carboxymethyl cellulose, 15g of cysteine ​​and 42.8g of zinc trifluoromethanesulfonate and add them to 128.4g of ultrapure water. Stir mechanically until completely uniformly mixed to obtain a preliminary mixed dispersion. Then transfer this preliminary mixed dispersion to a 200mL ball mill jar, set the speed to 400rpm, and continuously ball mill for 18h to obtain a completely uniformly mixed cathode electrode.

[0073] (2) Preparation of anolyte: Weigh 42.8g of zinc trifluoromethanesulfonate and add it to 128.4g of ultrapure water. Stir mechanically until the zinc salt is completely dissolved to obtain a uniformly mixed anolyte.

[0074] (3) Operational procedures for zinc electrodeposition: such as Figure 1 As shown, the cathode slurry electrode liquid prepared above was mixed at a rate of 5 mL / min. -1 The solution is pumped into a 200 mL cathodic electrolytic cell at a flow rate of [missing information] and circulated back to the cathode tank. Separately, the prepared anodic electrode solution is pumped into the anodic electrolytic cell, and an insertion area of ​​12 cm² is formed in the cathodic electrolytic cell. 2 The carbon cloth current collector, inserted into the anolyte in the anolyte electrolytic cell, has a surface coated with 3 mg / cm³. 2 A carbon cloth current collector for manganese dioxide electrocatalyst is used, with an NKK TF45 type aqueous diaphragm inserted between the two electrodes. Then, copper wires and electrode tabs are connected, with a current of 10 mA / cm². 2 Electrolysis was performed at a current density for 2 hours, and a zinc slurry containing electrodeposited zinc nanoparticles was obtained on one side of the cathode electrolytic cell.

[0075] Example 2

[0076] The preparation method is the same as in Example 1, except that in step (1), 20g of cysteine ​​is added to 128.4g of ultrapure water.

[0077] Example 3

[0078] The preparation method is the same as in Example 1, except that in step (1), 25g of cysteine ​​is added to 128.4g of ultrapure water.

[0079] Example 4

[0080] The preparation method is the same as in Example 1, except that in step (1), 30g of cysteine ​​is added to 128.4g of ultrapure water.

[0081] The zinc paste products prepared after electrodeposition in Examples 1-4 were analyzed by transmission electron microscopy and tested by electrochemical performance of the three-electrode system. The results are shown in Table 1.

[0082] The performance parameters of zinc slurry systems prepared with different amounts of organic ligands after electrodeposition are shown in Table 1 below.

[0083] Table 1 Electrochemical performance tests of the flowable conductive zinc slurry systems in Examples 1-4

[0084]

[0085] The discharge polarization curves of zinc electrodeposition in a flowable zinc slurry system were recorded using a Blue Battery testing system, such as... Figure 3 As shown, the discharge curve plateaued. With the gradual increase of organic ligand content, the overpotential and charge transfer resistance of the slurry system began to decrease. This indicates that the added organic ligands gradually constructed a solvation structure for zinc ions, lowering the barrier to interfacial electron transfer and thus reducing energy loss. This is consistent with the result of continuously increasing energy efficiency. However, excessive organic ligands can lead to aggregation, which is detrimental to the formation of zinc species in the system. High-resolution transmission electron microscopy analysis of the zinc slurry product obtained by electrodeposition yielded the following results: Figure 4 As shown in (a) and (b), from Figure 4 (a) It can be seen that zinc nanoparticles with uniform particle size distribution were generated, from Figure 4 (b) A high-resolution image of the magnified zinc particles shows clear lattice fringes corresponding to the zinc crystalline phase. Furthermore, it is noteworthy that the average particle size of the zinc particles gradually decreases with the introduction of organic ligands, indicating that the organic ligands have a significant molecular confinement effect on zinc grain nucleation and subsequent growth, effectively preventing zinc metal from continuously growing and agglomerating. This zinc slurry system features a concentrated distribution of electrodeposited zinc particle size, limited overpotential and charge transfer resistance, and high energy efficiency, making it highly valuable for practical applications in the field of electrochemical hydrogen production.

[0086] Example 5

[0087] This embodiment provides a method for chemical hydrogen production using the zinc slurry solid filter material obtained after electrodeposition, comprising the following steps:

[0088] (1) The slurry product containing electrodeposited zinc obtained in the cathode tank after electrolysis in Examples 1-4 above was subjected to vacuum filtration to obtain zinc slurry solid filter material and cathode filtrate, such as Figure 2 As shown;

[0089] (2) Collect the electrode liquid after reaction in the anode tank in Examples 1-4 above to obtain the anode residue;

[0090] (3) Add 60g of sulfuric acid and 100g of water to the zinc slurry solid filter material in step (1) above, stir until uniformly mixed, and use a gas cylinder to collect the hydrogen gas produced by the reaction to obtain the reaction cathode residual slurry.

[0091] Example 6

[0092] The preparation method is the same as in Example 5, except that in step (3), 60g of hydrochloric acid and 100g of water are added to the zinc slurry solid filter material.

[0093] Example 7

[0094] The preparation method is the same as in Example 5, except that in step (3), 100g of hydrochloric acid and 100g of water are added to the zinc slurry solid filter material.

[0095] Example 8

[0096] The preparation method is the same as in Example 5, except that in step (3), 180g of hydrochloric acid and 100g of water are added to the zinc slurry solid filter material.

[0097] Example 9

[0098] This embodiment provides a method for preparing a recyclable, regenerated cathode flowable conductive zinc slurry system and an anode electrolyte, including the following steps:

[0099] (1) In Examples 5-8 above, the cathode filtrate collected in step (1) and the reaction residue slurry in step (3) are mixed and mechanically stirred until homogeneous to obtain the mother liquor of the slurry to be regenerated, such as Figure 2 As shown;

[0100] (2) While stirring, add 15g of water to the above-mentioned mother liquor of the slurry to be regenerated, then add 2g of sodium hydroxide to adjust the pH of the slurry to 4, and obtain the mother liquor of the slurry to be regenerated.

[0101] (3) Transfer the above-mentioned mother liquor of slurry to be regenerated to a ball mill jar and ball mill at 500 rpm for 36 hours to obtain a regenerated flowable conductive zinc slurry system that can be used as the electrolytic reaction in step (3) of Examples 1-4.

[0102] (4) Weigh 30g of water and 2g of sodium hydroxide and add them to the anolyte in step (2) of Examples 5-8. Stir mechanically until the mixture is uniform, adjust the pH of the anolyte to 4, and obtain the regenerated anolyte, which can be used for the electrolysis reaction in step (3) of Examples 1-4.

[0103] Example 10

[0104] The preparation method is the same as in Example 9, except that 2g of potassium hydroxide is added in step (2) to adjust the pH of the slurry to 4, while 2g of potassium hydroxide is added in step (4) to adjust the pH of the anolyte to 4.

[0105] Example 11

[0106] The preparation method is the same as in Example 9, except that 5g of potassium hydroxide is added in step (2) to adjust the pH of the slurry to 5, while 5g of potassium hydroxide is added in step (4) to adjust the pH of the anolyte to 5.

[0107] Example 12

[0108] The preparation method is the same as in Example 9, except that 8g of potassium hydroxide is added in step (2) to adjust the pH of the slurry to 6, while 8g of potassium hydroxide is added in step (4) to adjust the pH of the anolyte to 6.

[0109] Comparative Example 1

[0110] This comparative example provides a preparation method and application of a common aqueous zinc plate electrolysis system, serving as a comparative example to the flowable conductive zinc slurry system disclosed in this invention, and includes the following steps:

[0111] (1) Preparation of cathode electrode system: 42.8g of zinc trifluoromethanesulfonate was weighed and added to 128.4g of ultrapure water. The solution was mechanically stirred until completely dissolved to obtain the cathode electrolyte. The surface of a 1mm thick copper plate was wiped clean with ethanol and then cut into 12cm² pieces using a slicer. 2 The included electrode pads are ready for use.

[0112] (2) Preparation of anolyte: Weigh 42.8g of zinc trifluoromethanesulfonate and add it to 128.4g of ultrapure water. Stir mechanically until the zinc salt is completely dissolved to obtain a uniformly mixed anolyte.

[0113] (3) Electrodeposition of zinc procedure: The copper plate prepared above is used as the cathode-side current collector and inserted into the cathode electrolytic cell. Then, the cathode electrolyte is added at a rate of 5 mL / min. -1 The solution is pumped into a 200 mL cathodic electrolytic cell at a flow rate of [missing information] and circulated back to the cathode tank. Separately, the prepared anodic electrode solution is pumped into the anodic electrolytic cell, and an insertion area of ​​12 cm² is formed in the cathodic electrolytic cell. 2 The carbon cloth current collector, inserted into the anolyte in the anolyte electrolytic cell, has a surface coated with 3 mg / cm³. 2 A carbon cloth current collector for manganese dioxide electrocatalyst is used, with an NKK TF45 type aqueous diaphragm inserted between the two electrodes. Then, copper wires and electrode tabs are connected, with a current of 10 mA / cm². 2 Electrolysis was performed at a current density for 2 hours, resulting in plate-type zinc deposition on the surface of the cathode copper plate current collector.

[0114] The zinc products obtained by electrodeposition in the zinc plate electrolysis system of the above comparative example were observed by scanning electron microscopy, such as... Figure 5 Combined with elemental surface scan results, it was found that zinc was deposited on the copper substrate in a dendritic form. These dendrites can easily pierce the diaphragm in practical applications, leading to short-circuit failure of the electrolysis system. Further XRD phase analysis, such as... Figure 6 As can be seen, compared to the pure zinc phase in the product of fluidized zinc slurry deposition, zinc plate deposition contains many impurities of basic zinc sulfate. These impurities are the main reason for the consumption of zinc species and electrolyte, resulting in low coulombic efficiency and poor reversibility of the system. Figure 7 As shown.

[0115] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A flowable conductive zinc paste, characterized in that, It includes an aqueous solution of zinc salt, a conductive agent, a dispersant, and an organic ligand, wherein the mass ratio of the aqueous solution of zinc salt, the conductive agent, the dispersant, and the organic ligand is (50-280):(10-60):(5-50):(5-40).

2. The flowable conductive zinc paste according to claim 1, characterized in that, The zinc salt aqueous solution is one or a combination of two or more of the following: zinc sulfate aqueous solution, zinc chloride aqueous solution, zinc sulfide aqueous solution, zinc perchlorate aqueous solution, zinc trifluoromethanesulfonate aqueous solution, zinc nitrate aqueous solution, and zinc acetate aqueous solution.

3. The flowable conductive zinc paste according to claim 1, characterized in that, The conductive agent is one or a combination of two or more of the following: conductive carbon black, Ketjen black, acetylene black, Cabot carbon black, carbon nanotubes, and graphene.

4. The flowable conductive zinc paste according to claim 1, characterized in that, The dispersant is one or a combination of two or more of the following: polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, carboxymethyl cellulose, polyethylene oxide, polyacrylamide, and polyacrylic acid.

5. The flowable conductive zinc paste according to claim 1, characterized in that, The organic ligand is one or a combination of two or more of the following: cysteine, cystine, glutamic acid, glycine, methionine, mercaptoacetic acid, mercaptopropionic acid, mercaptobutyric acid, mercaptoethanol, mercaptopropanol, mercaptobutanol, glutathione, mercaptoethylamine, mercaptopropylamine, and mercaptobutylamine.

6. A method for preparing a flowable conductive zinc paste according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Weigh 10-60 parts by weight of conductive agent, 5-50 parts by weight of dispersant, 5-40 parts by weight of organic ligand, 20-80 parts by weight of zinc salt, and 30-200 parts by weight of water, and mechanically stir until uniformly mixed to obtain a preliminary mixed dispersion. S2. Transfer the preliminary mixed dispersion obtained in step S1 to a ball mill jar and ball mill at a speed of 100-1000 rpm for 2-48 hours to obtain a uniformly mixed conductive zinc slurry.

7. The application of the flowable conductive zinc paste according to any one of claims 1 to 5 in hydrogen production, characterized in that, The conductive zinc slurry is used as the cathode slurry electrode liquid for two-step hydrogen production.

8. The hydrogen production application of the flowable conductive zinc paste according to claim 7, characterized in that, Includes the following steps: The first step involves using the conductive zinc slurry as the cathode slurry electrode liquid and feeding it into an electrolytic cell for electrolysis to obtain electrodeposited zinc nanoparticles, while simultaneously collecting oxygen byproducts at the anode. The second step involves introducing the electrodeposited zinc nanoparticles into an inorganic acid solution for reaction, producing hydrogen gas which is then collected.

9. The hydrogen production application of the flowable conductive zinc paste according to claim 8, characterized in that, Specifically, the following steps are included: (1) Use the conductive zinc paste as the cathode paste electrode liquid, at a concentration of 1-100 mL·min -1 The flow rate is pumped into the cathode electrolytic cell and circulated back to the cathode tank. The anolyte is pumped into the anolyte electrolytic cell, and the anolyte is inserted into the cathode electrolytic cell with an area of ​​2-30 cm². 2 The conductive current collector is inserted into the anodic electrolytic cell with a surface coating of 0.5-10 mg / cm². 2 The conductive current collector for the oxygen evolution catalyst has a solid diaphragm inserted between the two electrodes and then operates at 10-1000 mA / cm. 2 Electrolysis is carried out at a current density for 0.5-15 hours to obtain electrodeposited zinc slurry products in the cathode electrolytic cell, while oxygen is obtained by electrolysis in the anodic electrolytic cell and collected. (2) Vacuum filter the electrodeposited zinc slurry product to obtain the electrodeposited zinc nanoparticle-conductive agent composite and filtrate. Add 50-200 parts by weight of inorganic acid and 20-120 parts by weight of water to the electrodeposited zinc nanoparticle-conductive agent composite, stir until uniformly mixed, collect the hydrogen gas produced by the reaction, and obtain the reaction cathode residual slurry. In step (1), the anolyte is an aqueous solution of zinc salt.

10. The hydrogen production application of the flowable conductive zinc paste according to claim 9, characterized in that, It also includes the following steps: (3) Mix the filtrate from step (2) with the residual slurry from the reaction cathode and stir mechanically until homogeneous to obtain the slurry to be regenerated; (4) While stirring, add 5-30 parts by weight of water to the slurry to be regenerated in step (3), and then add 1-10 parts by weight of solid alkali to adjust the pH of the slurry to between 3 and 7 to obtain the slurry mother liquor to be regenerated. (5) Transfer the mother liquor of the slurry to be regenerated obtained in step (4) to a ball milling jar and ball mill at a speed of 100-1000 rpm for 2-48 hours to obtain the regenerated conductive zinc slurry.

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