Aqueous zinc-based dual-ion battery and preparation method thereof

Abstract

The invention belongs to the technical field of batteries, and particularly relates to an aqueous zinc-based dual-ion battery and a preparation method thereof. The method comprises the following steps: 1) preparing a positive pole piece: uniformly mixing oxygen-containing ammonium salt and a solvent, dropwise adding an acid solution to adjust the pH value of a system to obtain a solution, continuously adding the solvent to dilute the solution, adding the ammonium salt to obtain a hydrothermal reaction medium, additionally taking carbon cloth, cleaning, drying, putting the hydrothermal reaction medium, carrying out hydrothermal reaction, taking out the carbon cloth, and cleaning and drying the carbon cloth to obtain the positive pole piece; 2) preparing a negative pole piece: cutting, cleaning and drying the base material to obtain the negative pole piece; and 3) assembling the aqueous zinc-based dual-ion battery: uniformly mixing a zinc salt, an ammonium salt and a solvent to obtain an electrolyte, and immersing the positive pole piece and the negative pole piece into the electrolyte to obtain the aqueous zinc-based dual-ion battery. The aqueous zinc-based dual-ion battery prepared by the invention has the advantages of large specific capacity, good battery cycle performance, strong stability and prolonged service life.

Description

Technical Field

[0001] The invention belongs to the technical field of batteries, and in particular relates to an aqueous zinc-based double-ion battery and a preparation method thereof. Background Art

[0002] Aqueous rechargeable batteries have attracted much attention in the field of large-scale energy storage due to their low cost, high safety, and environmental friendliness. Recently, rechargeable zinc-based ion batteries and aqueous electrolytes have received extensive attention due to the advantages of abundant and cheap raw materials for rechargeable zinc-based ion batteries and the safety of aqueous electrolytes. Although the zinc negative electrode has obvious advantages, aqueous zinc-ion batteries (AZBs) have key problems that hinder their commercialization, such as narrow working window, positive electrode structure collapse, dendrite growth, and negative electrode surface corrosion. Zn 2+ The strong electrostatic and solvation effects of Zn limit the reaction kinetics of the battery, resulting in poor rate performance and specific capacity of the battery. 2+ Afterwards, the structure of the positive electrode material collapses, resulting in a poor battery life.

[0003] In order to solve these problems, researchers have adopted various methods, among which the multi-ion engineering strategy is considered to be able to overcome the problems of traditional zinc-ion batteries and has been formally proposed and gradually promoted. This strategy has been applied to the AZBs system, which effectively improves the reaction kinetics, prolongs the battery cycle life, and increases the operating voltage. The multi-ion engineering strategy is to embed / extract ions on the positive electrode side without changing the valence state. In the multi-ion engineering strategy, Li + 、Na + , K + Mg 2+ 、Al 3+ Additional ions such as metal ions have been widely studied and show good application prospects, but the research on additional ions of non-metal ions is still relatively small.

[0004] NH4 + It is a sustainable charge carrier that can be artificially synthesized from hydrogen and nitrogen sources, which is sustainable and resource-rich. + As the energy storage electrode of charge carrier, it has rich topological chemistry. During the insertion / extraction process, NH4 + The ZnO2 can form hydrogen bonds with the atoms of the electrode materials O and N to achieve a higher storage capacity. 2+ and NH4 + dual-ion batteries, exploring new paths to further improve the storage capacity and cycle performance of AZBs. Summary of the invention

[0005] Based on the above content, in order to solve the problem of limited performance of existing aqueous zinc ion batteries, the present invention proposes an aqueous zinc-based dual-ion battery and a preparation method thereof.

[0006] The objects of the present invention are: 1. Improve the storage capacity of aqueous zinc-ion batteries; 2. Enhance the cycle performance of aqueous zinc-ion batteries.

[0007] To achieve the above objectives, the present invention adopts the following technical solutions.

[0008] A method for preparing an aqueous zinc-based dual-ion battery, The method comprises: 1) Preparation of positive electrode sheet: take oxygen-containing ammonium salt and solvent and mix them evenly, add acid solution to adjust the pH value of the system to obtain a solution, continue to add solvent to dilute the solution, add ammonium salt to obtain a hydrothermal reaction medium, take carbon cloth, wash and dry it, put it into the hydrothermal reaction medium, after hydrothermal reaction, take out the carbon cloth, wash and dry it to obtain the positive electrode sheet; 2) Preparation of negative electrode sheet: cutting, cleaning and drying the substrate to obtain the negative electrode sheet; 3) Assembling an aqueous zinc-based dual-ion battery: zinc salt, ammonium salt and solvent are mixed evenly to obtain an electrolyte, and the positive electrode and the negative electrode are immersed in the electrolyte to obtain an aqueous zinc-based dual-ion battery.

[0009] As a preference, Step 1) the oxygen-containing ammonium salt is ammonium tungstate; Step 1) The solvent is water, and an oxygen-containing ammonium salt solution with a concentration of 10 to 15 mmol / L is prepared.

[0010] As a preference, Step 1) The acid solution is dilute sulfuric acid with a concentration of 2.5-3.5 mol / L, and the pH value of the system is adjusted to 1-1.5.

[0011] As a preference, Step 1) The dilution is to dilute the ammonium tungstate contained in the solution to a concentration of 3.3-7.5 mmol / L.

[0012] As a preference, Step 1) The ammonium salt is ammonium sulfate, and its usage is 19-20 g / L solution.

[0013] As a preference, Step 1) The cleaning method is to immerse the carbon cloth in acetone, ethanol and deionized water respectively, and ultrasonically clean it for 15 to 20 minutes.

[0014] As a preference, Step 1) The hydrothermal reaction is carried out at a constant temperature of 1 to 3 MPa and 160 to 200°C for 16 to 24 hours.

[0015] As a preference, Step 2) The substrate is zinc foil.

[0016] As a preference, Step 2) The cleaning method is to immerse the substrate in dilute sulfuric acid and deionized water respectively, and ultrasonically clean it for 15 to 20 minutes.

[0017] As a preference, Step 3) the zinc salt is zinc sulfate; Step 3) the ammonium salt is ammonium sulfate; Step 3) The solvent is water, the concentration of zinc sulfate in the electrolyte is 0.6-1.4 mol / L, and the concentration of ammonium sulfate is 0.1-0.9 mol / L.

[0018] As a preference, Step 3) The positive electrode sheet and the negative electrode sheet are used in an area ratio of (8-10):1.

[0019] An aqueous zinc-based double-ion battery.

[0020] Tungstic acid cannot be directly dissolved in water to form a solution containing tungstate, so the present invention uses ammonium tungstate to prepare a solution. In the technical solution of the present invention, ammonium tungstate has excellent properties such as low interfacial impedance. When added to the positive electrode material of the battery, it can effectively improve the conduction of ions, increase the battery charge and discharge rate, and enhance the battery cycle stability. The ammonium tungstate in the solution is well dispersed, and then cooperates with ammonium sulfate to form a micro-nano structure through a hydrothermal reaction. Compared with heating in an ammonium tungstate solution, the morphology is completely different. Due to a certain "recombination" phenomenon and the synergistic effect of non-deposited ions, the tunnel-like structure of the battery is stable, which improves the electrochemical performance of the positive electrode material. The tunnel-like structure can promote the transport and coordination of zinc ions. The radius of the embedded ammonium ions (143 pm) is similar to that of the zinc ions (135 pm), which improves the lattice phase change and battery volume expansion problems associated with the ion embedding-extraction process, appropriately widens the migration channel of zinc ions, and promotes charge diffusion.

[0021] In order to suppress the capacity decay of the battery caused by structural collapse, the present invention controls the concentration of ammonium ions in the solution by adding ammonium sulfate. As the concentration of ammonium ions increases, the electronic state of the induced atoms changes, so that the material can obtain a higher capacity. The concentration of ammonium ions will have a greater impact on the product morphology. Within the concentration range defined by the present invention, the resulting product morphology is a radial needle array structure with a large specific surface area and high structural stability, which can produce a good tunnel effect. However, insufficient ammonium ions will cause the particles to be difficult to distribute evenly and form an orderly distributed nano needle-like structure. The carbon cloth structure is not stable enough, and the energy barrier and charge transfer barrier of the ammonium ion diffusion path are high, resulting in the inability of zinc ions to be well transmitted, thereby affecting its cycle stability.

[0022] At the same time, the reaction parameters set in the present invention can ensure that NH4 is pre-embedded on the carbon cloth. + (NH4) x The loading amount of WO3 is high. When the reaction temperature is low, a stable loading effect cannot be produced, and even effective product conversion cannot be formed. When the temperature is too high, the nano morphology will be affected, resulting in the inability to form an orderly distributed nano needle structure.

[0023] In addition, the concentrations of ammonium ions and zinc ions provided in the mixed electrolyte prepared by the present invention will significantly affect the efficiency of the electrochemical process. Among them, zinc sulfate provides zinc ions, and the concentration of zinc sulfate has a significant effect on the specific capacity of the battery. High concentrations of zinc sulfate are helpful to capacity improvement, but too high a concentration of zinc sulfate will cause the cycle life of the battery to decrease. Ammonium sulfate can increase the conductivity of the solution and expand the current density range used. According to the research of those skilled in the art, the higher the concentration of ammonium ions, the greater the number of ions, the better the conductivity of the solution, the enhanced conductivity of the current, and the increase in the specific capacity of the battery. It can be seen that a high-concentration mixed electrolyte has a higher specific capacity, but after the capacity reaches a certain value, the number of cycles will decrease, and further, it is manifested as a large decrease in the specific capacity of the battery. It has been found through experiments that the concentration of zinc sulfate and the concentration of ammonium sulfate need to be adjusted and adapted to each other to achieve better performance.

[0024] In the present invention, ammonium ions are pre-embedded (NH4) x In the WO3 positive electrode material, the structure of the carbon-based material is stabilized, effectively reducing the NH4 + The energy barrier and charge transfer barrier in the diffusion path improve the adsorption performance, thereby significantly improving the charge transfer rate. The pre-embedding of ammonium ions in the aqueous zinc ion battery system can significantly improve the kinetic performance of the battery and extend the cycle life. After characterization, it was found that the aqueous zinc ion battery prepared by the present invention has a large storage capacity and good cycle performance.

[0025] The beneficial effects of the present invention are as follows: (1) The aqueous zinc-based dual-ion battery prepared by the present invention has a large specific capacity; (2) Aqueous zinc-based dual-ion batteries have good cycle performance and strong stability, which extends their service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the assembled zinc-based dual-ion battery; Figure 2 (NH4) prepared in Example 1 x XRD characterization diagram of WO3 positive electrode; Figure 3 (NH4) prepared in Example 1 x SEM characterization of WO3 positive electrode; Figure 4 (NH4) x The charge and discharge curves of the battery with WO3 as the positive electrode and zinc sheet as the negative electrode and different electrolyte compositions; (a) 1 mol / L ZnSO4; (b) 0.5 mol / L (NH4)2SO4; (c) 1 mol / L ZnSO4+0.5 mol / L (NH4)2SO4; (d) Comparison of the charge and discharge curves of the three electrolytes at a current density of 0.2 A / g; Figure 5 This is a comparison chart of the cycling performance of three electrolytes. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with specific embodiments and the accompanying drawings. A person of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without making creative work should fall within the scope of protection of the present invention.

[0028] Unless otherwise specified, the raw materials used in the examples of the present invention are all commercially available or available to those skilled in the art; unless otherwise specified, the methods used in the examples of the present invention are all methods known to those skilled in the art.

[0029] Unless otherwise specified, the surface area of ​​the carbon cloth used in the embodiments of the present invention is 25 cm 3 , the effective carbon component weighs 7.5 g.

[0030] Example 1 A method for preparing an aqueous zinc-based dual-ion battery, The method comprises: 1) Preparation of positive electrode sheet: take ammonium tungstate and water and mix them evenly to prepare a 10 mmol / L ammonium tungstate solution. Take the ammonium tungstate solution, add 3 mol / L dilute sulfuric acid, adjust the pH value of the system to 1.5, and obtain a solution. Continue to add water to dilute the ammonium tungstate in the solution to a concentration of 7.5 mmol / L. Take 70 mL of the solution and add 1.33 g of ammonium sulfate to obtain a hydrothermal reaction medium. Take another carbon cloth and immerse it in acetone, ethanol and deionized water respectively. Ultrasonic cleaning for 15 min, dry it and put it into the hydrothermal reaction medium. Keep the temperature at 3 MPa and 160 °C for 24 h. Take out the carbon cloth, clean it and dry it to obtain a positive electrode sheet. 2) Preparation of negative electrode sheet: Cut the zinc foil, immerse it in dilute sulfuric acid and deionized water respectively, clean it with ultrasonic for 15 min, and dry it to obtain the negative electrode sheet; 3) Assembling an aqueous zinc-based dual-ion battery: zinc sulfate, ammonium sulfate and water are mixed evenly to obtain an electrolyte, wherein the concentration of zinc sulfate is 1 mol / L and the concentration of ammonium sulfate is 0.1 mol / L. Positive electrode sheets and negative electrode sheets are taken at an area ratio of 8:1, and the positive electrode sheets and negative electrode sheets are immersed in the electrolyte to obtain an aqueous zinc-based dual-ion battery 1.

[0031] The capacity and cycle performance of the aqueous zinc-based dual-ion battery prepared in this example were tested. At a current density of 0.2 A / g, a two-electrode system was used for testing. x WO3 is used as the positive electrode and Zn is used as the negative electrode. The test results are as follows. First discharge specific capacity (mAh / g) Charge specific capacity (mAh / g) Coulomb efficiency (%) Stable cycle times 150.83 144.34 95.7 1200 0.2C cycle retention rate (%) 0.5C cycle retention rate (%) 1.0C cycle retention rate (%) 2.0C cycle retention rate (%) 92.8 89.2 82.1 72.5

[0032] After the above performance characterization, the battery was disassembled for macroscopic observation of the positive and negative electrodes, and no bulging occurred. At a high rate of 20C, the first discharge capacity of the battery in this example can still reach 145.3 mAh / g. After 1000 cycles, the battery assembled by the present invention still has a discharge capacity of 130.77 mAh / g.

[0033] Aqueous zinc-based dual-ion batteries Figure 1 As shown, for (NH4) x The WO3 cathode material was characterized and tested, and the XRD pattern was as follows: Figure 2 As shown, the SEM characterization results are further shown in Figure 3 As shown, it can be seen that the synthesized (NH4) x The surface of WO3 is in the shape of nano needles.

[0034] Only ammonium sulfate was added to the electrolyte in step 3) until its concentration reached 0.3 mol / L, and an aqueous zinc-based dual-ion battery 1-a was prepared. The capacity and cycle performance of the battery were tested. At a current density of 0.2 A / g, a two-electrode system was used for testing. The prepared (NH4) x WO3 is used as the positive electrode and Zn is used as the negative electrode. The test results are as follows. First discharge specific capacity (mAh / g) Charge specific capacity (mAh / g) Coulomb efficiency (%) Stable cycle times 165.15 158.71 96.1 1200 0.2C cycle retention rate (%) 0.5C cycle retention rate (%) 1.0C cycle retention rate (%) 2.0C cycle retention rate (%) 93.4 90.1 83.6 73.3

[0035] Only ammonium sulfate was added to the electrolyte in step 3) until its concentration reached 0.5 mol / L to prepare an aqueous zinc-based dual-ion battery 1-b, and its capacity, cycle performance, etc. were tested. At a current density of 0.2 A / g, a two-electrode system was used for testing. The prepared (NH4) x WO3 is used as the positive electrode and Zn is used as the negative electrode. The test results are as follows. First discharge specific capacity (mAh / g) Charge specific capacity (mAh / g) Coulomb efficiency (%) Stable cycle times 157.61 152.57 96.8 1200 0.2C cycle retention rate (%) 0.5C cycle retention rate (%) 1.0C cycle retention rate (%) 2.0C cycle retention rate (%) 94.8 91.5 84.5 73.9

[0036] Only ammonium sulfate was added to the electrolyte in step 3) until its concentration reached 0.7 mol / L to prepare an aqueous zinc-based dual-ion battery 1-c. The capacity and cycle performance of the battery were tested. At a current density of 0.2 A / g, a two-electrode system was used to test the prepared (NH4) x WO3 is used as the positive electrode and Zn is used as the negative electrode. The test results are as follows. First discharge specific capacity (mAh / g) Charge specific capacity (mAh / g) Coulomb efficiency (%) Stable cycle times 165.67 158.71 95.8 1000 0.2C cycle retention rate (%) 0.5C cycle retention rate (%) 1.0C cycle retention rate (%) 2.0C cycle retention rate (%) 92.9 89.8 81.3 72.4

[0037] Only ammonium sulfate was added to the electrolyte in step 3) until its concentration reached 0.9 mol / L, and an aqueous zinc-based dual-ion battery 1-d was prepared. The capacity and cycle performance of the battery were tested. At a current density of 0.2 A / g, a two-electrode system was used for testing. The prepared (NH4) x WO3 is used as the positive electrode and Zn is used as the negative electrode. The test results are as follows. First discharge specific capacity (mAh / g) Charge specific capacity (mAh / g) Coulomb efficiency (%) Stable cycle times 169.53 160.38 94.6 900 0.2C cycle retention rate (%) 0.5C cycle retention rate (%) 1.0C cycle retention rate (%) 2.0C cycle retention rate (%) 91.6 87.3 80.2 70.5

[0038] Ammonium sulfate can increase the conductivity of the solution and expand the current density range used. According to research by those skilled in the art, the higher the ammonium ion concentration, the greater the number of ions, the better the conductivity of the solution, the enhanced current conductivity, and the increased specific capacity of the battery. According to the results in the above table, the batteries prepared in this example all have good cycle performance and stability, among which the aqueous zinc-based dual-ion battery 1-b has the highest first charge and discharge coulomb efficiency, and its specific capacity is large while ensuring the cycle performance. When the battery specific capacity is further improved, it is found that the battery cycle performance is significantly deteriorated.

[0039] Example 2 A method for preparing an aqueous zinc-based dual-ion battery, The method comprises: 1) Preparation of positive electrode sheet: take ammonium tungstate and water and mix them evenly to prepare a 10 mmol / L ammonium tungstate solution. Take the ammonium tungstate solution, add 3 mol / L dilute sulfuric acid, adjust the pH value of the system to 1.5, and obtain a solution. Continue to add water to dilute the ammonium tungstate in the solution to a concentration of 7.5 mmol / L. Take 70 mL of the solution and add 1.33 g of ammonium sulfate to obtain a hydrothermal reaction medium. Take another carbon cloth and immerse it in acetone, ethanol and deionized water respectively. Ultrasonic cleaning for 15 min, dry it and put it into the hydrothermal reaction medium. Keep the temperature at 3 MPa and 160 °C for 24 h. Take out the carbon cloth, clean it and dry it to obtain a positive electrode sheet. 2) Preparation of negative electrode sheet: Cut the zinc foil, immerse it in dilute sulfuric acid and deionized water respectively, clean it with ultrasonic for 15 min, and dry it to obtain the negative electrode sheet; 3) Assembling an aqueous zinc-based dual-ion battery: zinc sulfate, ammonium sulfate and water are mixed evenly to obtain an electrolyte, wherein the concentration of zinc sulfate is 0.6 mol / L and the concentration of ammonium sulfate is 0.5 mol / L. Positive electrode sheets and negative electrode sheets are taken at an area ratio of 8:1, and the positive electrode sheets and negative electrode sheets are immersed in the electrolyte to obtain an aqueous zinc-based dual-ion battery 1.

[0040] The capacity and cycle performance of the aqueous zinc-based dual-ion battery prepared in this example were tested. At a current density of 0.2 A / g, a two-electrode system was used for testing. x WO3 is used as the positive electrode and Zn is used as the negative electrode. The test results are as follows. First discharge specific capacity (mAh / g) Charge specific capacity (mAh / g) Coulomb efficiency (%) Stable cycle times 118.32 106.72 90.2 1200 0.2C cycle retention rate (%) 0.5C cycle retention rate (%) 1.0C cycle retention rate (%) 2.0C cycle retention rate (%) 89.8 86.5 80.1 70.6

[0041] After the above performance characterization, the battery was disassembled and the positive and negative electrodes were observed macroscopically, and no bulging occurred.

[0042] The battery of this example can still achieve an initial discharge capacity of 114.63 mAh / g at a high rate of 20C. The battery assembled by the present invention still has a discharge capacity of 98.44 mAh / g after 1000 cycles.

[0043] Only zinc sulfate was added to the electrolyte in step 3) until its concentration reached 0.8 mol / L, and an aqueous zinc-based dual-ion battery 1-1 was prepared. The capacity and cycle performance of the battery were tested. At a current density of 0.2 A / g, a two-electrode system was used for testing. The prepared (NH4) x WO3 is used as the positive electrode and Zn is used as the negative electrode. The test results are as follows. First discharge specific capacity (mAh / g) Charge specific capacity (mAh / g) Coulomb efficiency (%) Stable cycle times 139.68 127.67 91.4 1200 0.2C cycle retention rate (%) 0.5C cycle retention rate (%) 1.0C cycle retention rate (%) 2.0C cycle retention rate (%) 90.3 87.2 82.6 72.0

[0044] Only zinc sulfate was added to the electrolyte in step 3) until its concentration reached 1.2 mol / L, and an aqueous zinc-based dual-ion battery 1-2 was prepared. The capacity and cycle performance of the battery were tested. At a current density of 0.2 A / g, a two-electrode system was used for testing. The prepared (NH4) x WO3 is used as the positive electrode and Zn is used as the negative electrode. The test results are as follows. First discharge specific capacity (mAh / g) Charge specific capacity (mAh / g) Coulomb efficiency (%) Stable cycle times 156.43 144.38 92.3 1000 0.2C cycle retention rate (%) 0.5C cycle retention rate (%) 1.0C cycle retention rate (%) 2.0C cycle retention rate (%) 92.4 89.6 81.9 71.5

[0045] Only zinc sulfate was added to the electrolyte in step 3) until its concentration reached 1.4 mol / L, and aqueous zinc-based dual-ion batteries 1-3 were prepared. The capacity and cycle performance of the batteries were tested. At a current density of 0.2 A / g, a two-electrode system was used for testing. The prepared (NH4) x WO3 is used as the positive electrode and Zn is used as the negative electrode. The test results are as follows. First discharge specific capacity (mAh / g) Charge specific capacity (mAh / g) Coulomb efficiency (%) Stable cycle times 165.82 150.40 90.7 900 0.2C cycle retention rate (%) 0.5C cycle retention rate (%) 1.0C cycle retention rate (%) 2.0C cycle retention rate (%) 91.5 88.6 80.4 70.9

[0046] According to the results in the above table, the concentration of zinc sulfate will significantly affect the specific capacity of the battery. A high concentration of zinc sulfate is helpful to improve the capacity to a certain extent, but too high a concentration of zinc sulfate will lead to a decrease in the cycle life of the battery. Combined with the characterization results of the aqueous zinc-based dual-ion battery 1-b in Example 1, a high-concentration mixed electrolyte generally has a higher specific capacity, but the number of cycles will inevitably decrease after the capacity increases. In addition, the concentration of zinc sulfate and the concentration of ammonium sulfate need to be adjusted and adapted to each other to achieve better performance. According to the results in the tables of Example 1 and Example 2, it was found that the battery prepared with 1 mol / LZnSO4+0.5 mol / L (NH4)2SO4 as the electrolyte has the best performance. A battery was assembled with 1 mol / L ZnSO4+0.5mol / L (NH4)2SO4 as the electrolyte and the above-mentioned positive and negative electrodes for constant current charge and discharge (GCD) testing. The resulting GCD curve is as shown in the figure. Figure 4 (c) as shown.

[0047] Example 3 A method for preparing an aqueous zinc-based dual-ion battery, The method comprises: 1) Preparation of positive electrode sheet: take ammonium tungstate and water and mix them evenly to prepare a 10 mmol / L ammonium tungstate solution. Take the ammonium tungstate solution, add 3 mol / L dilute sulfuric acid, adjust the pH value of the system to 1.5, and obtain a solution. Continue to add water to dilute the ammonium tungstate in the solution to a concentration of 7.5 mmol / L. Take 70 mL of the solution and add 1.4 g of ammonium sulfate to obtain a hydrothermal reaction medium. Take another carbon cloth and immerse it in acetone, ethanol and deionized water respectively. Ultrasonic cleaning for 15 min, dry it and put it into the hydrothermal reaction medium. Keep the temperature at 3 MPa and 160 °C for 24 h. Take out the carbon cloth, clean it and dry it to obtain a positive electrode sheet. 2) Preparation of negative electrode sheet: Cut the zinc foil, immerse it in dilute sulfuric acid and deionized water respectively, clean it with ultrasonic for 15 min, and dry it to obtain the negative electrode sheet; 3) Assembling an aqueous zinc-based dual-ion battery: zinc sulfate, ammonium sulfate and water are mixed evenly to obtain an electrolyte, wherein the concentration of zinc sulfate is 1 mol / L and the concentration of ammonium sulfate is 0.5 mol / L. Positive electrode sheets and negative electrode sheets are taken at an area ratio of 8:1, and the positive electrode sheets and negative electrode sheets are immersed in the electrolyte to obtain an aqueous zinc-based dual-ion battery 1.

[0048] The capacity and cycle performance of the aqueous zinc-based dual-ion battery prepared in this example were tested. At a current density of 0.2 A / g, a two-electrode system was used for testing. x WO3 is used as the positive electrode and Zn is used as the negative electrode. The test results are as follows. First discharge specific capacity (mAh / g) Charge specific capacity (mAh / g) Coulomb efficiency (%) Stable cycle times 158.94 153.85 96.8 1200 0.2C cycle retention rate (%) 0.5C cycle retention rate (%) 1.0C cycle retention rate (%) 2.0C cycle retention rate (%) 94.7 91.3 84.2 73.7

[0049] After the above performance characterization, the battery was disassembled and the positive and negative electrodes were observed macroscopically, and no bulging occurred.

[0050] The battery of this example can still achieve an initial discharge capacity of 155.16 mAh / g at a high rate of 20C. The battery assembled by the present invention still has a discharge capacity of 142.06 mAh / g after 1000 cycles.

[0051] After characterization, it was found that the electrode sheet in this example has a radial needle array structure, with a large specific surface area and high structural stability, which can produce a good tunnel effect and the battery has no obvious capacity decay. According to the results in the table, it is confirmed that the battery in this example has no structural collapse. In addition, due to the increase in the concentration of ammonium ions in this example, the electronic state of the atoms changes, and the battery can obtain a higher capacity.

[0052] Comparative Example 1 A method for preparing an aqueous zinc-based dual-ion battery, The method comprises: 1) Preparation of positive electrode sheet: take ammonium tungstate and water and mix them evenly to prepare a 10 mmol / L ammonium tungstate solution. Take the ammonium tungstate solution, add 3 mol / L dilute sulfuric acid, adjust the pH value of the system to 1.5, and obtain a solution. Continue to add water to dilute the ammonium tungstate in the solution to a concentration of 7.5 mmol / L. Take 70 mL of the solution and add 1 g of ammonium sulfate to obtain a hydrothermal reaction medium. Take another carbon cloth and immerse it in acetone, ethanol and deionized water respectively. Ultrasonic cleaning for 15 min, dry it and put it into the hydrothermal reaction medium. Keep the temperature at 3 MPa and 160 °C for 24 h. Take out the carbon cloth, clean it and dry it to obtain a positive electrode sheet. 2) Preparation of negative electrode sheet: Cut the zinc foil, immerse it in dilute sulfuric acid and deionized water respectively, clean it with ultrasonic for 15 min, and dry it to obtain the negative electrode sheet; 3) Assembling an aqueous zinc-based dual-ion battery: zinc sulfate, ammonium sulfate and water are mixed evenly to obtain an electrolyte, wherein the concentration of zinc sulfate is 1 mol / L and the concentration of ammonium sulfate is 0.5 mol / L. Positive electrode sheets and negative electrode sheets are taken at an area ratio of 8:1, and the positive electrode sheets and negative electrode sheets are immersed in the electrolyte to obtain an aqueous zinc-based dual-ion battery 1.

[0053] The capacity and cycle performance of the aqueous zinc-based dual-ion battery prepared in this example were tested. At a current density of 0.2 A / g, a two-electrode system was used for testing. x WO3 is used as the positive electrode and Zn is used as the negative electrode. The test results are as follows. First discharge specific capacity (mAh / g) Charge specific capacity (mAh / g) Coulomb efficiency (%) Stable cycle times 148.94 129.28 86.8 900 0.2C cycle retention rate (%) 0.5C cycle retention rate (%) 1.0C cycle retention rate (%) 2.0C cycle retention rate (%) 84.7 81.3 74.2 63.7

[0054] After the above performance characterization, the battery was disassembled and the positive and negative electrodes were observed macroscopically, and no bulging occurred.

[0055] In this case, insufficient ammonium ions will make it difficult for the particles to be evenly distributed and form an orderly distributed nano-needle structure. The carbon cloth structure is not stable enough, and the energy barrier and charge transfer barrier of the ammonium ion diffusion path are high, resulting in poor transmission of zinc ions, thus affecting the battery cycle stability.

[0056] Comparative Example 2 A method for preparing an aqueous zinc-based dual-ion battery, The method comprises: 1) Preparation of positive electrode sheet: take ammonium tungstate and water and mix them evenly to prepare a 10 mmol / L ammonium tungstate solution. Take the ammonium tungstate solution, add 3 mol / L dilute sulfuric acid, adjust the pH value of the system to 1.5, and obtain a solution. Continue to add water to dilute the ammonium tungstate in the solution to a concentration of 7.5 mmol / L. Take 70 mL of the solution and add 1.33 g of ammonium sulfate to obtain solution a. Take another carbon cloth and immerse it in acetone, ethanol and deionized water respectively. Ultrasonic cleaning for 15 min, dry it and put it into solution a, heat it to 160 °C, keep the temperature constant for 24 h, take out the carbon cloth, clean it and dry it to obtain a positive electrode sheet. 2) Preparation of negative electrode sheet: Cut the zinc foil, immerse it in dilute sulfuric acid and deionized water respectively, clean it with ultrasonic for 15 min, and dry it to obtain the negative electrode sheet; 3) Assembling an aqueous zinc-based dual-ion battery: zinc sulfate, ammonium sulfate and water are mixed evenly to obtain an electrolyte, wherein the concentration of zinc sulfate is 1 mol / L and the concentration of ammonium sulfate is 0.5 mol / L. Positive electrode sheets and negative electrode sheets are taken at an area ratio of 8:1, and the positive electrode sheets and negative electrode sheets are immersed in the electrolyte to obtain an aqueous zinc-based dual-ion battery 1.

[0057] The capacity and cycle performance of the aqueous zinc-based dual-ion battery prepared in this example were tested. At a current density of 0.2 A / g, a two-electrode system was used for testing. x WO3 is used as the positive electrode and Zn is used as the negative electrode. The test results are as follows. First discharge specific capacity (mAh / g) Charge specific capacity (mAh / g) Coulomb efficiency (%) Stable cycle times 146.94 125.34 85.3 900 0.2C cycle retention rate (%) 0.5C cycle retention rate (%) 1.0C cycle retention rate (%) 2.0C cycle retention rate (%) 80.1 75.3 70.6 61.6

[0058] After the above performance characterization, the battery was disassembled and the positive and negative electrodes were observed macroscopically, and no bulging occurred.

[0059] The morphology of the positive electrode sheet prepared in this example is different from that of the positive electrode sheet prepared in the example. Due to a certain "recombination" phenomenon and the synergistic effect of non-deposited ions, the tunnel-like structure of the battery in the example is stable, so the performance is better than that of the battery in this example. In this example, ammonium tungstate is locally agglomerated and does not form a uniform micro-nano structure, resulting in slow zinc ion transport speed and charge diffusion speed.

[0060] Comparative Example 3 A method for preparing an aqueous zinc-based dual-ion battery, The method comprises: 1) Preparation of positive electrode sheet: take ammonium tungstate and water and mix them evenly to prepare a 10 mmol / L ammonium tungstate solution. Take the ammonium tungstate solution, add 3 mol / L dilute sulfuric acid, adjust the pH value of the system to 1.5, and obtain a solution. Continue to add water to dilute the ammonium tungstate in the solution to a concentration of 7.5 mmol / L. Take 70 mL of the solution and add 1.4 g of ammonium sulfate to obtain a hydrothermal reaction medium. Take another carbon cloth and immerse it in acetone, ethanol and deionized water respectively. Ultrasonic cleaning for 15 min, dry it and put it into the hydrothermal reaction medium. Keep the temperature at 3 MPa and 140 °C for 24 h. Take out the carbon cloth, clean it and dry it to obtain a positive electrode sheet. 2) Preparation of negative electrode sheet: Cut the zinc foil, immerse it in dilute sulfuric acid and deionized water respectively, clean it with ultrasonic for 15 min, and dry it to obtain the negative electrode sheet; 3) Assembling an aqueous zinc-based dual-ion battery: zinc sulfate, ammonium sulfate and water are mixed evenly to obtain an electrolyte, wherein the concentration of zinc sulfate is 1 mol / L and the concentration of ammonium sulfate is 0.5 mol / L. Positive electrode sheets and negative electrode sheets are taken at an area ratio of 8:1, and the positive electrode sheets and negative electrode sheets are immersed in the electrolyte to obtain an aqueous zinc-based dual-ion battery 1.

[0061] The capacity and cycle performance of the aqueous zinc-based dual-ion battery prepared in this example were tested. At a current density of 0.2 A / g, a two-electrode system was used for testing. x WO3 is used as the positive electrode and Zn is used as the negative electrode. The test results are as follows. First discharge specific capacity (mAh / g) Charge specific capacity (mAh / g) Coulomb efficiency (%) Stable cycle times 147.35 127.61 86.6 900 0.2C cycle retention rate (%) 0.5C cycle retention rate (%) 1.0C cycle retention rate (%) 2.0C cycle retention rate (%) 80.7 76.6 72.8 60.4

[0062] After the above performance characterization, the battery was disassembled and the positive and negative electrodes were observed macroscopically, and no bulging occurred.

[0063] Under the reaction parameters set in this example, NH4 is pre-embedded on the carbon cloth. + (NH4) x As the WO3 loading decreases, it can be clearly seen that the battery prepared in this example has a small specific capacity and unstable cycle performance.

[0064] Comparative Example 4 A method for preparing an aqueous zinc-based dual-ion battery, The method comprises: 1) Preparation of positive electrode sheet: take ammonium tungstate and water and mix them evenly to prepare a 10 mmol / L ammonium tungstate solution. Take the ammonium tungstate solution, add 3 mol / L dilute sulfuric acid, adjust the pH value of the system to 1.5, and obtain a solution. Continue to add water to dilute the ammonium tungstate in the solution to a concentration of 7.5 mmol / L. Take 70 mL of the solution and add 1.33 g of ammonium sulfate to obtain a hydrothermal reaction medium. Take another carbon cloth and immerse it in acetone, ethanol and deionized water respectively. Ultrasonic cleaning for 15 min, dry it and put it into the hydrothermal reaction medium. Keep the temperature at 3 MPa and 160 °C for 24 h. Take out the carbon cloth, clean it and dry it to obtain a positive electrode sheet. 2) Preparation of negative electrode sheet: Cut the zinc foil, immerse it in dilute sulfuric acid and deionized water respectively, clean it with ultrasonic for 15 min, and dry it to obtain the negative electrode sheet; 3) Assembling an aqueous zinc-based dual-ion battery: zinc sulfate and water are mixed evenly to obtain an electrolyte with a zinc sulfate concentration of 0.6 mol / L, and positive and negative electrode sheets are taken at an area ratio of 8:1, and the positive and negative electrode sheets are immersed in the electrolyte to obtain an aqueous zinc-based dual-ion battery.

[0065] The capacity and cycle performance of the aqueous zinc-based dual-ion battery prepared in this example were tested. At a current density of 0.2 A / g, a two-electrode system was used for testing. x WO3 is used as the positive electrode and Zn is used as the negative electrode. The test results are as follows. First discharge specific capacity (mAh / g) Charge specific capacity (mAh / g) Coulomb efficiency (%) Stable cycle times 108.56 94.66 87.2 1200 0.2C cycle retention rate (%) 0.5C cycle retention rate (%) 1.0C cycle retention rate (%) 2.0C cycle retention rate (%) 80.7 76.6 72.8 60.4

[0066] After the above performance characterization, the battery was disassembled for macroscopic observation of the positive and negative electrodes, and no bulging occurred. In addition, at a constant current density of 0.2 A / g, the battery of the present invention can be stably cycled for more than 1200 times.

[0067] According to the results in the table of this example, the specific capacity of the battery prepared in this example is much smaller than that of the battery prepared in Example 3. This shows that zinc sulfate plays an important role in improving the specific capacity of the battery.

[0068] Only zinc sulfate was added to the electrolyte of step 3) until its concentration reached 0.8 mol / L, and an aqueous zinc-based dual-ion battery 1-o was prepared, and its capacity, cycle performance, etc. were tested. Only zinc sulfate was added to the electrolyte of step 3) until its concentration reached 1 mol / L, and an aqueous zinc-based dual-ion battery 1-p was prepared, and its capacity, cycle performance, etc. were tested. Only zinc sulfate was added to the electrolyte of step 3) until its concentration reached 1.2 mol / L, and an aqueous zinc-based dual-ion battery 1-q was prepared, and its capacity, cycle performance, etc. were tested. Only zinc sulfate was added to the electrolyte of step 3) until its concentration reached 1.4 mol / L, and an aqueous zinc-based dual-ion battery 1-r was prepared, and its capacity, cycle performance, etc. were tested. At a current density of 0.2 A / g, a two-electrode system was used for testing, and the prepared (NH4) x WO3 is used as the positive electrode and Zn is used as the negative electrode. The test results are as follows.

[0069] It can be clearly seen from the above table that the concentration of zinc sulfate has a significant effect on the specific capacity of the battery. A high concentration of zinc sulfate is helpful to improve the capacity to a certain extent, but too high a concentration of zinc sulfate will reduce the cycle life of the battery. Overall, 1 mol / L ZnSO4 has good performance as an electrolyte, which indirectly confirms that the battery prepared in the embodiment with 1 mol / L ZnSO4+0.5 mol / L (NH4)2SO4 as the electrolyte has the best performance. The prepared battery was subjected to a constant current charge and discharge (GCD) test, and the resulting GCD curve is shown in the figure. Figure 4 (a) shown.

[0070] Comparative Example 5 A method for preparing an aqueous zinc-based dual-ion battery, The method comprises: 1) Preparation of positive electrode sheet: take ammonium tungstate and water and mix them evenly to prepare a 10 mmol / L ammonium tungstate solution. Take the ammonium tungstate solution, add 3 mol / L dilute sulfuric acid, adjust the pH value of the system to 1.5, and obtain a solution. Continue to add water to dilute the ammonium tungstate in the solution to a concentration of 7.5 mmol / L. Take 70 mL of the solution and add 1.33 g of ammonium sulfate to obtain a hydrothermal reaction medium. Take another carbon cloth and immerse it in acetone, ethanol and deionized water respectively. Ultrasonic cleaning for 15 min, dry it and put it into the hydrothermal reaction medium. Keep the temperature at 3 MPa and 160 °C for 24 h. Take out the carbon cloth, clean it and dry it to obtain a positive electrode sheet. 2) Preparation of negative electrode sheet: Cut the zinc foil, immerse it in dilute sulfuric acid and deionized water respectively, clean it with ultrasonic for 15 min, and dry it to obtain the negative electrode sheet; 3) Assembling an aqueous zinc-based dual-ion battery: Take ammonium sulfate and water and mix them evenly to obtain an electrolyte with an ammonium sulfate concentration of 0.1 mol / L, take positive electrode sheets and negative electrode sheets according to an area ratio of 8:1, immerse the positive electrode sheets and negative electrode sheets in the electrolyte to obtain an aqueous zinc-based dual-ion battery.

[0071] The capacity and cycle performance of the aqueous zinc-based dual-ion battery prepared in this example were tested. At a current density of 0.2 A / g, a two-electrode system was used for testing. x WO3 is used as the positive electrode and Zn is used as the negative electrode. The test results are as follows. First discharge specific capacity (mAh / g) Charge specific capacity (mAh / g) Coulomb efficiency (%) Stable cycle times 68.42 55.83 83.6 1100 0.2C cycle retention rate (%) 0.5C cycle retention rate (%) 1.0C cycle retention rate (%) 2.0C cycle retention rate (%) 81.7 76.1 72.3 63.9

[0072] After the above performance characterization, the battery was disassembled for macroscopic observation of the positive and negative electrodes, and no bulging occurred. In addition, at a constant current density of 0.2 A / g, the battery of the present invention can be stably cycled for more than 1200 times.

[0073] Only ammonium sulfate was added to the electrolyte of step 3) until its concentration reached 0.3 mol / L, and an aqueous zinc-based dual-ion battery 1-u was prepared, and its capacity, cycle performance, etc. were tested. Only ammonium sulfate was added to the electrolyte of step 3) until its concentration reached 0.5 mol / L, and an aqueous zinc-based dual-ion battery 1-v was prepared, and its capacity, cycle performance, etc. were tested. Only ammonium sulfate was added to the electrolyte of step 3) until its concentration reached 0.7 mol / L, and an aqueous zinc-based dual-ion battery 1-w was prepared, and its capacity, cycle performance, etc. were tested. Only ammonium sulfate was added to the electrolyte of step 3) until its concentration reached 0.9 mol / L, and an aqueous zinc-based dual-ion battery 1-x was prepared, and its capacity, cycle performance, etc. were tested. At a current density of 0.2 A / g, a two-electrode system was used for testing, and the prepared (NH4) x WO3 is used as the positive electrode and Zn is used as the negative electrode. The test results are as follows.

[0074] It can be clearly seen from the above table that the concentration of ammonium sulfate has a certain influence on the specific capacity and cycle number of the battery. With the increase of the concentration of ammonium sulfate, the specific capacity and cycle number of the battery generally show a trend of first increasing and then decreasing. The best performance is achieved at 0.5 mol / L (NH4)2SO4. The battery is assembled with 0.5 mol / L (NH4)2SO4 as the electrolyte and the above positive and negative electrodes for constant current charge and discharge (GCD) test. The obtained GCD curve is as follows: Figure 4 (b) as shown.

[0075] in addition, Figure 4(d) is a comparison of GCD curves of batteries assembled with 1 mol / L ZnSO4, 0.5 mol / L (NH4)2SO4 and 1 mol / L ZnSO4 + 0.5 mol / L (NH4)2SO4 electrolytes and the above positive and negative electrodes at a current density of 0.2 A / g. Figure 4 (d) It can be clearly seen that the 1 mol / L ZnSO4+0.5 mol / L (NH4)2SO4 mixed electrolyte used in this example enables the battery to have the highest specific capacity. Figure 5 The figure shows a comparison of the cycling performance of three electrolytes, indicating that after 1200 cycles, the capacity retention rate of the 1 mol / L ZnSO4+0.5 mol / L (NH4)2SO4 mixed electrolyte is the highest.

Claims

1. A method for preparing an aqueous zinc-based dual-ion battery, characterized in that: The method comprises: 1) Preparation of positive electrode sheet: take oxygen-containing ammonium salt and solvent and mix them evenly, add acid solution to adjust the pH value of the system to obtain a solution, continue to add solvent to dilute the solution, add ammonium salt to obtain a hydrothermal reaction medium, take carbon cloth, wash and dry it, put it into the hydrothermal reaction medium, after hydrothermal reaction, take out the carbon cloth, wash and dry it to obtain the positive electrode sheet; 2) Preparation of negative electrode sheet: cutting, cleaning and drying the substrate to obtain the negative electrode sheet; 3) Assembling an aqueous zinc-based dual-ion battery: zinc salt, ammonium salt and solvent are mixed evenly to obtain an electrolyte, and the positive electrode and the negative electrode are immersed in the electrolyte to obtain an aqueous zinc-based dual-ion battery.

2. The method for preparing an aqueous zinc-based dual-ion battery according to claim 1, characterized in that: Step 1) the oxygen-containing ammonium salt is ammonium tungstate; Step 1) The solvent is water, and an oxygen-containing ammonium salt solution with a concentration of 10 to 15 mmol / L is prepared.

3. The method for preparing an aqueous zinc-based dual-ion battery according to claim 1, characterized in that: Step 1) The acid solution is dilute sulfuric acid with a concentration of 2.5-3.5 mol / L, and the pH value of the system is adjusted to 1-1.

5.

4. The method for preparing an aqueous zinc-based dual-ion battery according to claim 1, 2 or 3, characterized in that: Step 1) The dilution is to dilute the ammonium tungstate contained in the solution to a concentration of 3.3-7.5 mmol / L.

5. The method for preparing an aqueous zinc-based dual-ion battery according to claim 1, characterized in that: Step 1) The ammonium salt is ammonium sulfate, and its usage is 19-20 g / L solution.

6. The method for preparing an aqueous zinc-based dual-ion battery according to claim 1, characterized in that: Step 1) The cleaning method is to immerse the carbon cloth in acetone, ethanol and deionized water respectively, and ultrasonically clean it for 15 to 20 minutes; Step 1) The hydrothermal reaction is carried out at a constant temperature of 1 to 3 MPa and 160 to 200°C for 16 to 24 hours.

7. The method for preparing an aqueous zinc-based dual-ion battery according to claim 1, characterized in that: Step 2) the substrate is zinc foil; Step 2) The cleaning method is to immerse the substrate in dilute sulfuric acid and deionized water respectively, and ultrasonically clean it for 15 to 20 minutes.

8. The method for preparing an aqueous zinc-based dual-ion battery according to claim 1, characterized in that: Step 3) the zinc salt is zinc sulfate; Step 3) the ammonium salt is ammonium sulfate; Step 3) The solvent is water, the concentration of zinc sulfate in the electrolyte is 0.6-1.4 mol / L, and the concentration of ammonium sulfate is 0.1-0.9 mol / L.

9. The method for preparing an aqueous zinc-based dual-ion battery according to claim 1 or 8, characterized in that: Step 3) The positive electrode sheet and the negative electrode sheet are used in an area ratio of (8-10):

1.

10. An aqueous zinc-based dual-ion battery prepared by the method of any one of claims 1 to 9.

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