Doped zinc-based negative electrode and preparation method and application thereof

Abstract

The invention provides a doped zinc-based negative electrode and a preparation method and application thereof, and the preparation method comprises the following steps: (1) mixing a zinc source, a doped metal source, a phase separating agent and a solvent to obtain a precursor solution; (2) mixing the precursor solution with a gel accelerator, and performing aging treatment to obtain a precursor; and (3) carrying out heat treatment on the precursor to obtain the doped zinc-based negative electrode. The doped zinc-based negative electrode has a porous structure, the problem of negative electrode failure caused by dendritic crystal growth can be effectively relieved, doped metal elements and zinc oxide are uniformly compounded, corrosion of the zinc negative electrode in the charging and discharging process is effectively inhibited, and the cycle life is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery materials and relates to a doped zinc-based negative electrode and a preparation method and application thereof. Background Art

[0002] The intermittent and unstable nature of wind and solar power generation poses significant challenges to the smooth operation of the power grid, while also providing opportunities for the development of high-performance energy storage equipment. Compared to traditional lead-acid batteries and the widely used lithium-ion batteries, aqueous zinc-ion batteries utilize zinc metal anodes and aqueous electrolytes. These batteries offer advantages such as abundant resources, low cost, safety, environmental protection, and non-toxicity. They are expected to become an ideal choice for future large-scale, low-cost electrochemical energy storage. Aqueous zinc-nickel batteries, with their open-circuit voltage reaching 1.75V and excellent rate performance, have garnered widespread attention. However, zinc anode failure results in a short cycle life for existing zinc-nickel batteries, severely impacting their practical application.

[0003] Nickel-zinc batteries use zinc metal as the negative electrode and high-concentration KOH as the electrolyte. However, Zn and its oxidation product ZnO are prone to corrosion and dissolution in strong alkaline electrolytes, leading to severe corrosion, dendrites, and passivation, which ultimately lead to electrode failure and affect the cycle life of nickel-zinc batteries. Introducing additives or composite modifications into the zinc negative electrode is an important way to improve the performance of the zinc negative electrode. In the high-performance, long-life zinc-nickel battery negative electrode slurry disclosed in CN111193009B, one or more of indium oxide, bismuth oxide, aluminum oxide, and lead oxide are used as additives to improve the cycle stability of the zinc negative electrode. CN110137477B uses one or two of indium oxide and bismuth oxide as inorganic corrosion inhibitors. However, the above additive methods are difficult to achieve uniform mixing, which increases the weight of the entire electrode.

[0004] CN114759168A discloses a method for preparing a co-doped nanoporous zinc-based alloy integrated negative electrode. This method involves doping with one or more of Cu, Ni, or Al through alloy preparation and chemical dealloying to produce the porous material. However, this method is complex and suffers from poor pore structure continuity. Therefore, an efficient method for preparing a porous doped zinc negative electrode is urgently needed.

[0005] The zinc-based negative electrode prepared by the above scheme has the problem of uneven distribution of doping elements and poor pore continuity, which will lead to negative electrode dendrites and side reactions, resulting in a shorter cycle life of the battery. Summary of the Invention

[0006] The purpose of the present invention is to provide a doped zinc-based negative electrode and its preparation method and application. The doped zinc-based negative electrode has a porous structure, which can effectively alleviate the problem of negative electrode failure caused by dendrite growth, and the doped metal elements and zinc oxide are uniformly compounded, effectively inhibiting the corrosion of the zinc negative electrode during the charging and discharging process, thereby improving the cycle life.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a doped zinc-based negative electrode, the preparation method comprising the following steps:

[0009] (1) mixing a zinc source, a doping metal source, a phase separation agent, and a solvent to obtain a precursor solution;

[0010] (2) mixing the precursor solution and a gel accelerator, and subjecting the mixture to an aging treatment to obtain a precursor;

[0011] (3) heat-treating the precursor to obtain the doped zinc-based negative electrode.

[0012] The present invention adopts a sol-gel phase separation method to prepare a transition metal element-doped zinc oxide porous block. The transition metal oxide and zinc oxide materials are evenly composited, which can more effectively inhibit the corrosion of the zinc negative electrode during the battery charging and discharging process and improve the cycle life.

[0013] Preferably, the zinc source in step (1) comprises zinc chloride.

[0014] Preferably, the doping metal source includes any one of cerium salt, tin salt, lanthanum salt, yttrium salt or europium salt, or a combination of at least two of them.

[0015] Preferably, the phase separation agent comprises any one or a combination of at least two of polyacrylic acid, polyethylene oxide, polyvinyl pyrrolidone or a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer.

[0016] Preferably, the solvent includes water and an organic solvent.

[0017] Preferably, the organic solvent includes any one of glycerol, ethylene glycol, ethanol, isopropanol or methanol, or a combination of at least two thereof.

[0018] Preferably, the volume ratio of water to organic solvent is 1:(1-10).

[0019] Preferably, the molar ratio of the doping metal in the doping metal source and the zinc in the zinc source in step (1) is (1-5):100, for example: 1:100, 2:100, 3:100, 4:100 or 5:100, etc.

[0020] Preferably, the molar mass ratio of the zinc element in the zinc source to the phase separation agent is 1:(0.4-1.5) mol / kg, for example: 1:0.4 mol / kg, 1:0.6 mol / kg, 1:1 mol / kg, 1:1.2 mol / kg or 1:1.5 mol / kg, etc.

[0021] Preferably, the mixing in step (1) is followed by stirring.

[0022] Preferably, the stirring time is 1 to 3 hours, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours.

[0023] Preferably, the concentration of zinc ions in the precursor solution is 0.1 to 0.2 mol / L, for example, 0.1 mol / L, 0.12 mol / L, 0.15 mol / L, 0.18 mol / L or 0.2 mol / L.

[0024] Preferably, the gel accelerator in step (2) comprises any one of propylene oxide, urea, ethanolamine, diethylamine, hexylamine or hexadecylamine, or a combination of at least two thereof.

[0025] Preferably, the pH of the mixed system is 6.8 to 7.2, for example, 6.8, 6.9, 7, 7.1 or 7.2.

[0026] Preferably, the mixing is followed by stirring and ultrasonic defoaming treatment.

[0027] Preferably, the stirring time is 3 to 8 minutes, for example, 3 minutes, 4 minutes, 5 minutes, 7 minutes or 8 minutes.

[0028] Preferably, the ultrasonic defoaming treatment time is 20 to 40 seconds, for example, 20 seconds, 25 seconds, 30 seconds, 35 seconds or 40 seconds.

[0029] Preferably, the aging treatment in step (2) is carried out under sealed conditions.

[0030] Preferably, the temperature of the aging treatment is 40-80°C, for example, 40°C, 50°C, 60°C, 70°C or 80°C.

[0031] Preferably, the aging treatment time is 20 to 30 hours, for example, 20 hours, 22 hours, 25 hours, 28 hours or 30 hours.

[0032] Preferably, after the aging treatment in step (3), the solvent is poured out and washing treatment is performed.

[0033] Preferably, the detergent of the washing treatment comprises ethanol.

[0034] Preferably, the heat treatment in step (3) is carried out under vacuum or inert atmosphere.

[0035] Preferably, the gas of the inert atmosphere includes nitrogen and / or argon.

[0036] Preferably, the temperature of the heat treatment is 150-800°C, for example, 150°C, 200°C, 300°C, 500°C or 800°C.

[0037] Preferably, the heat treatment time is 0.5 to 8 hours, for example, 0.5 hours, 1 hour, 3 hours, 5 hours or 8 hours.

[0038] In a second aspect, the present invention provides a doped zinc-based negative electrode, which is prepared by the method described in the first aspect.

[0039] Preferably, the doped zinc-based negative electrode has a block-shaped porous structure.

[0040] The co-continuous porous structure of the doped zinc-based negative electrode of the present invention can effectively improve the fluidity of the electrolyte and expand the specific surface area of ​​the zinc negative electrode. At the same time, the pore structure can also effectively alleviate the problem of negative electrode failure caused by dendrite growth, ultimately improving the reliability of the zinc-nickel battery negative electrode.

[0041] In a third aspect, the present invention provides a nickel-zinc battery, comprising the doped zinc-based negative electrode as described in the second aspect.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] (1) The present invention prepares a doped zinc oxide block through a sol-gel phase separation method, which has a co-continuous porous structure and can effectively inhibit the negative electrode failure problem caused by dendrite growth. At the same time, the porous structure can effectively increase the reaction area.

[0044] (2) The sol-gel phase separation method is used to achieve doping, and the doped metal elements and zinc oxide are evenly compounded, which effectively inhibits the corrosion of the zinc negative electrode during the charge and discharge process and improves the cycle life.

[0045] (3) The nickel-zinc battery made of the doped zinc-based negative electrode prepared by the method of the present invention can have a cycle capacity retention rate of ≥80% at 0.1C for more than 406 cycles. DETAILED DESCRIPTION

[0046] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0047] Example 1

[0048] This embodiment provides a doped zinc-based negative electrode, and the preparation method of the doped zinc-based negative electrode is as follows:

[0049] (1) Zinc chloride, cerium chloride, polyacrylic acid, and solvent (deionized water and glycerol in a volume ratio of 1:1) were stirred at room temperature until completely dissolved. The zinc ion concentration was 0.15 mol / L, the cerium ion concentration was 2% of the zinc ion concentration, and the amount of polyacrylic acid was 1.0 kg per 1 mol of zinc ion. The mixture was stirred for 2 h to obtain a precursor solution.

[0050] (2) Propylene oxide was added to the precursor solution until the system pH was 7, and after stirring for 5 minutes, the bubbles were removed by ultrasonication for 30 seconds, and the solution was sealed and gelled at 60°C and aged for 24 hours. The remaining solvent was then poured out and the solution was washed with ethanol three times to obtain the precursor;

[0051] (3) The precursor is heat-treated in a vacuum at a temperature of 600° C. for 4 hours to obtain the doped zinc-based negative electrode.

[0052] Example 2

[0053] This embodiment provides a doped zinc-based negative electrode, and the preparation method of the doped zinc-based negative electrode is as follows:

[0054] (1) Zinc chloride, yttrium chloride, polyethylene oxide, and solvent (deionized water and isopropyl alcohol in a volume ratio of 1:2) were stirred at room temperature until completely dissolved. The zinc ion concentration was 0.2 mol / L, the yttrium ion concentration was 5% of the zinc ion concentration, and the amount of polyethylene oxide was 1.5 kg per 1 mol of zinc ion. Stirring was continued for 2 h to obtain a precursor solution.

[0055] (2) Propylene oxide was added to the precursor solution until the system pH was 6.8, and after stirring for 3 minutes, the bubbles were removed by ultrasonication for 40 seconds, and the solution was sealed and gelled at 40°C and aged for 30 hours. The remaining solvent was then poured out and the solution was washed with ethanol three times to obtain a precursor;

[0056] (3) The precursor is heat-treated in a nitrogen atmosphere at a temperature of 300° C. for 6 hours to obtain the doped zinc-based negative electrode.

[0057] Example 3

[0058] This embodiment provides a doped zinc-based negative electrode, and the preparation method of the doped zinc-based negative electrode is as follows:

[0059] (1) Zinc chloride, europium nitrate, polyvinyl pyrrolidone, and solvent (deionized water and ethanol in a volume ratio of 1:5) were stirred at room temperature until completely dissolved. The zinc ion concentration was 0.1 mol / L, the europium ion concentration was 1% of the zinc ion concentration, and the amount of polyvinyl pyrrolidone was 0.5 kg per 1 mol of zinc ion. The mixture was stirred for 2 h to obtain a precursor solution.

[0060] (2) Propylene oxide was added to the precursor solution until the system pH was 7.2, and after stirring for 5 minutes, the bubbles were removed by ultrasonication for 20 seconds, and the solution was sealed and gelled at 40°C and aged for 30 hours. The remaining solvent was then poured out and the solution was washed with ethanol three times to obtain a precursor;

[0061] (3) The precursor is heat-treated in a nitrogen atmosphere at a temperature of 800° C. for 0.5 h to obtain the doped zinc-based negative electrode.

[0062] Example 4

[0063] The only difference between this embodiment and embodiment 1 is that the cerium ion concentration is 0.5% of the zinc ion concentration (ie, the molar ratio of the doping metal in the doping metal source to the zinc in the zinc source is 0.5:100). Other conditions and parameters are exactly the same as those in embodiment 1.

[0064] Example 5

[0065] The only difference between this embodiment and embodiment 1 is that the cerium ion concentration is 8% of the zinc ion concentration (ie, the molar ratio of the doping metal in the doping metal source to the zinc in the zinc source is 8:100), and other conditions and parameters are exactly the same as those in embodiment 1.

[0066] Example 6

[0067] The only difference between this embodiment and embodiment 1 is that the amount of polyacrylic acid used is 0.2 kg per 1 mol of zinc ion (i.e., the molar mass ratio of zinc element in the zinc source to the phase separation agent is 1:0.2 mol / kg), and the other conditions and parameters are exactly the same as those in embodiment 1.

[0068] Example 7

[0069] The only difference between this embodiment and embodiment 1 is that the amount of polyacrylic acid used is 2 kg per 1 mol of zinc ion (i.e., the molar mass ratio of zinc element in the zinc source to the phase separation agent is 1:2 mol / kg), and the other conditions and parameters are exactly the same as those in embodiment 1.

[0070] Comparative Example 1

[0071] The only difference between this comparative example and Example 1 is that cerium is not doped, and other conditions and parameters are exactly the same as those in Example 1.

[0072] Performance testing:

[0073] Nickel hydroxide was used as the positive electrode, 6 mol / L potassium hydroxide aqueous solution was used as the electrolyte, zinc-based negative electrodes were prepared in the examples and comparative examples, and glass fiber films were used as separators to assemble nickel-zinc batteries. The cycle stability at 0.1C was tested. The test results are shown in Table 1:

[0074] Table 1

[0075] Number of cycles with 0.1C capacity retention rate ≥ 80% Example 1 423 Example 2 457 Example 3 406 Example 4 277 Example 5 269 Example 6 Unable to form blocks and assemble zinc-nickel batteries Example 7 178 Comparative Example 1 152

[0076] As can be seen from Table 1, from Examples 1-3, the nickel-zinc battery made of the doped zinc-based negative electrode prepared by the method of the present invention can have a cycle capacity retention rate of ≥80% at 0.1C for more than 406 cycles.

[0077] By comparing Example 1 with Examples 4-5, it can be seen that in the preparation process of the doped zinc-based negative electrode of the present invention, the molar ratio of the doping metal in the doping metal source and the zinc in the zinc source affects its performance. The molar ratio of the doping metal in the doping metal source and the zinc in the zinc source is controlled at 1 to 5:100, and the doped zinc-based negative electrode has better performance. If the amount of doping metal added is too large, the formation of the porous block structure is affected, and part of the pore structure is destroyed. At the same time, if the amount of doping metal added is too small, the corrosion of the zinc negative electrode cannot be effectively suppressed, resulting in a decrease in cycle performance.

[0078] By comparing Example 1 with Examples 6-7, it can be seen that in the preparation process of the doped zinc-based negative electrode of the present invention, the amount of phase separation agent used will affect its performance. The molar mass ratio of the zinc element in the zinc source to the phase separation agent is controlled at 1: (0.4~1.5) mol / kg, and the doped zinc-based negative electrode with better performance is obtained. If the amount of phase separation agent added is too large, the block is dense and the negative electrode failure caused by dendrite growth cannot be effectively suppressed. If the amount of phase separation agent added is too small, the skeleton is too fine and the structure collapses, and a better pore structure cannot be obtained.

[0079] From the comparison between Example 1 and Comparative Example 1, it can be seen that doping with metal can effectively inhibit the corrosion of the zinc negative electrode during the charge and discharge process and improve the cycle life.

[0080] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing a doped zinc-based negative electrode, characterized in that: The preparation method comprises the following steps: (1) mixing a zinc source, a doping metal source, a phase separation agent, and a solvent to obtain a precursor solution; (2) mixing the precursor solution and a gel accelerator, and subjecting the mixture to an aging treatment to obtain a precursor; (3) heat-treating the precursor to obtain the doped zinc-based negative electrode.

2. The preparation method according to claim 1, wherein The zinc source in step (1) comprises zinc chloride; Preferably, the doping metal source comprises any one of cerium salt, tin salt, lanthanum salt, yttrium salt or europium salt, or a combination of at least two thereof; Preferably, the phase separation agent comprises any one or a combination of at least two of polyacrylic acid, polyethylene oxide, polyvinyl pyrrolidone or a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer; Preferably, the solvent includes water and an organic solvent; Preferably, the organic solvent comprises any one or a combination of at least two of glycerol, ethylene glycol, ethanol, isopropanol or methanol; Preferably, the volume ratio of water to organic solvent is 1:(1-10).

3. The preparation method according to claim 1 or 2, wherein The molar ratio of the doping metal in the doping metal source to the zinc in the zinc source in step (1) is (1-5):100; Preferably, the molar mass ratio of the zinc element in the zinc source to the phase separation agent is 1:(0.4-1.5) mol / kg.

4. The preparation method according to any one of claims 1 to 3, wherein Stirring after mixing in step (1); Preferably, the stirring time is 1 to 3 hours; Preferably, the concentration of zinc ions in the precursor solution is 0.1 to 0.2 mol / L.

5. The preparation method according to any one of claims 1 to 4, characterized in that The gel accelerator in step (2) comprises any one of propylene oxide, urea, ethanolamine, diethylamine, hexylamine or hexadecylamine, or a combination of at least two thereof; Preferably, the pH of the mixed system is 6.8 to 7.2; Preferably, the mixing is followed by stirring and ultrasonic defoaming treatment; Preferably, the stirring time is 3 to 8 minutes; Preferably, the ultrasonic defoaming treatment lasts for 20 to 40 seconds.

6. The preparation method according to any one of claims 1 to 5, characterized in that The aging treatment in step (2) is carried out under sealed conditions; Preferably, the temperature of the aging treatment is 40-80°C; Preferably, the aging treatment time is 20 to 30 hours.

7. The preparation method according to any one of claims 1 to 6, characterized in that After the aging treatment in step (3), the solvent is poured out and washing is performed; Preferably, the detergent of the washing treatment comprises ethanol.

8. The preparation method according to any one of claims 1 to 7, wherein The heat treatment in step (3) is carried out under vacuum or inert atmosphere; Preferably, the gas of the inert atmosphere includes nitrogen and / or argon; Preferably, the heat treatment temperature is 150-800°C; Preferably, the heat treatment time is 0.5 to 8 hours.

9. A doped zinc-based negative electrode, characterized in that: The doped zinc-based negative electrode is prepared by the method according to any one of claims 1 to 8; Preferably, the doped zinc-based negative electrode has a block-shaped porous structure.

10. A nickel-zinc battery, characterized in that: The nickel-zinc battery comprises the doped zinc-based negative electrode as claimed in claim 9.