Flaky nh4v3o8 electrode material and preparation method thereof

Abstract

The application relates to the field of batteries, and discloses a flaky NH4V3O8 electrode material and a preparation method thereof, which comprises the following steps: S1, mixing a vanadium-containing solution and an ammonium salt to obtain a mixed solution; S2, adjusting the pH of the mixed solution to 4-6, and performing a precipitation reaction under the condition of 20-85 DEG C to obtain a slurry; S3, adding a morphology adjusting agent into the slurry, performing a reaction under the condition of a temperature of 90-100 DEG C to obtain post-reaction materials, and performing post-treatment on the post-reaction materials to obtain the flaky NH4V3O8 electrode material. The flaky NH4V3O8 electrode material with high purity and excellent electrochemical performance can be prepared.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a sheet-like NH4V3O8 electrode material and its preparation method. Background Technology

[0002] Layered vanadate NH4V3O8 has V3O8 - Layer and interlayer NH4 + The unique structure of the ions provides efficient insertion / extraction channels for lithium ions. Thanks to this structural advantage, the material exhibits high specific capacity and excellent rate performance, making it a highly attractive cathode material for lithium batteries.

[0003] Patent CN104701517B discloses a method for preparing NH4V3O8 cathode material for lithium-ion batteries. This method uses ammonium metavanadate (NH4VO3) as a raw material, dissolving it in deionized water to form a solution, and adding 1-3 mm of pre-oxidized short-cut carbon fibers as a morphology modifier. After adjusting the pH, the mixed solution is transferred to a reaction vessel for forced stirring, sealed, and placed in a hydrothermal induction heater to complete the reaction, generating a suspension. Finally, after centrifugation, alternating washing with deionized water and anhydrous ethanol, drying, and grinding, the target product NH4V3O8 is obtained. This method can achieve the directional synthesis of specific morphologies (such as nanoribbons or sheet structures) by precisely controlling hydrothermal parameters (such as temperature, time, and pH), but it suffers from problems such as insufficient product structural stability, low tolerance for process parameter errors, and high cost of carbon fiber pretreatment.

[0004] Patent CN110255616A discloses a process for synthesizing ultrathin nanosheet-like NH4V3O8 based on ultra-high pressure technology. The core steps include: dissolving 1-methyl-3-ethylimidazolium chloride (an ionic liquid) in water, adding ethylenediaminetetraacetic acid (EDTA) to form a mixed solution; subsequently adding NH4VO3 and pretreating the solution using microwaves; and finally completing crystal growth in an ultra-high pressure hydrothermal reactor. After centrifugation, washing, and drying, sheet-like NH4V3O8 with a thickness of <10 nm is obtained. This material exhibits excellent rate performance and high specific capacity when used as a cathode in lithium-ion batteries, but the process relies on ultra-high pressure equipment and expensive ionic liquids, leading to a significant increase in industrialization costs.

[0005] The article "Cao SS, Huang JF, Ouyang HB, et al. A simple method to prepare NH4V3O8 nanorods as cathode material for Li-ion batteries[J]. Materials Letters, 2014, 126:20-23" discloses a template-free, surfactant-free, low-cost water bath method for synthesizing NH4V3O8 nanorods. The specific steps are as follows: 0.585 g of NH4VO3 is dissolved in deionized water to form a pale yellow solution; hydrochloric acid is added dropwise to adjust the pH to approximately 2.0; the solution is transferred to a sealed beaker and kept at a constant temperature of 90°C in a water bath for 2 hours; after natural cooling to room temperature, the solution is filtered, washed several times alternately with deionized water and ethanol, and finally dried at 60°C for 6 hours to obtain the product. Although this method is simple to operate and has a low reaction temperature, avoiding the complexity of hydrothermal methods, the raw material used is ammonium metavanadate, which has high raw material costs. The vanadium concentration in the solution after dissolution is too low, greatly affecting the yield and productivity. Furthermore, the product has poor uniformity and severe aggregation, which will affect its rate performance.

[0006] It can be seen that the mainstream preparation method at present is still the hydrothermal method. Although the hydrothermal method can directly prepare nanomaterials with high crystallinity and controllable morphology under specific conditions, it also faces prominent problems. For example: high equipment cost (requiring high temperature and high pressure resistant reactors and temperature control systems), complex process control and high safety risks, difficult product separation, limited solvent applicability, and bottlenecks in large-scale production (uneven heat transfer, poor product consistency) and process unobservability.

[0007] Therefore, it is necessary to study a preparation scheme for NH4V3O8 electrode materials that is based on direct preparation from primary vanadium-containing raw materials, has a simplified process, low cost, high product purity, and is industrially feasible. Summary of the Invention

[0008] The main objective of this invention is to provide a sheet-like NH4V3O8 electrode material and its preparation method, in order to solve the problems of high equipment cost and complex process control caused by the hydrothermal method for preparing NH4V3O8 electrode material in the prior art, as well as the problem of high raw material cost caused by using ammonium metavanadate as raw material.

[0009] According to one aspect of the present invention, a method for preparing sheet-like NH4V3O8 electrode material is provided, comprising the following steps: S1, mixing a vanadium-containing solution and an ammonium salt to obtain a mixed solution; S2, adjusting the pH of the mixed solution to 4-6, and carrying out a precipitation reaction at 20-85°C to obtain a slurry; S3, adding a morphology modifier to the slurry, and carrying out a reaction at 90-100°C to obtain a post-reaction material, and performing post-treatment on the post-reaction material to obtain the sheet-like NH4V3O8 electrode material.

[0010] According to one embodiment of the present invention, the vanadium-containing solution contains pentavalent vanadium.

[0011] According to one embodiment of the present invention, the vanadium-containing solution is selected from at least one of the following: vanadium nitride solution obtained by sodium roasting-water leaching process, vanadium calcide solution obtained by calcification roasting-acid leaching process, and vanadium extraction solution from coal shale.

[0012] According to one embodiment of the present invention, the ammonium salt is selected from at least one of the following: ammonium sulfate, ammonium carbonate, ammonium bicarbonate, ammonium chloride, monoammonium hydrogen phosphate, diammonium hydrogen phosphate, and ammonia.

[0013] According to one embodiment of the present invention, in step S1, the vanadium-containing solution and the ammonium salt are mixed in a molar ratio n(NH4) + Mix n(V) = (0.6~2.3):1.

[0014] According to one embodiment of the present invention, the morphology modifier is selected from at least one of the following: hexadecyltrimethylammonium bromide, dodecylbenzene sulfonate.

[0015] According to one embodiment of the present invention, in step S2, the reaction time is 30~120 min.

[0016] According to one embodiment of the present invention, in step S3, the ratio of the amount of morphology modifier added to the volume of slurry is 0.05~0.5 g / L, and the reaction is carried out under stirring conditions for a reaction time of 60~120 min.

[0017] According to one embodiment of the present invention, in step S3, the post-processing of the reaction material includes: filtering the reaction material to obtain vanadium precipitate, and washing and drying the vanadium precipitate.

[0018] According to another aspect of the present invention, a sheet-like NH4V3O8 electrode material is provided, which is prepared by the method described above. The purity of the sheet-like NH4V3O8 electrode material is greater than 99.5%, and the microstructure is sheet-like.

[0019] In the technical solution of this invention, the pH of a mixed solution obtained by mixing a vanadium-containing solution and an ammonium salt is first adjusted to 4-6, and a precipitation reaction is carried out at a low temperature of 20-85°C to obtain a slurry containing a precipitate. The vanadium in the precipitate exists in the form of decavanadate. Then, a morphology modifier is added to the slurry, and the slurry is heated to 90-100°C. At this time, the vanadate groups undergo depolymerization and reforming under a weakly acidic environment, transforming from high-polymerization-degree decavanadate to low-polymerization-degree trivanadate. Under the action of the morphology modifier, the growth of specific crystal faces is selectively guided by controlling the depolymerization rate, thereby achieving morphology self-assembly and finally obtaining a sheet-like NH4V3O8 electrode material. The sheet-like morphology can provide a huge specific surface area to increase active sites and significantly improve capacity; its nanoscale thickness greatly shortens the ion diffusion path, giving the electrode excellent fast charge and discharge capabilities; at the same time, the sheet structure can effectively alleviate volume changes during charge and discharge, improving cycle stability. These characteristics work together to give the electrode the potential for high capacity, high power, and long life. Sheet-like materials, with their extremely high specific surface area, hold great promise for providing high capacity and constructing dense electrodes, especially suitable for compact devices and micro-energy storage components that require high energy density. Furthermore, highly polymerized vanadate ions (such as decavanadate) have larger molecular sizes and more complex spatial configurations, with more coordinate-unsaturated vanadium-oxygen bonds on their surfaces. This allows them to adsorb a larger amount of impurity ions through stronger electrostatic interactions and more coordination exchange sites. In contrast, low-polymerized vanadate ions can form pure ammonium vanadate salts and adsorb fewer impurity ions. Therefore, the method of this invention can not only prepare sheet-like NH4V3O8 electrode materials but also effectively improve the purity of the material. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A flowchart illustrating a method for preparing sheet-like NH4V3O8 electrode material according to an embodiment of the present invention is shown.

[0022] Figure 2 The X-ray diffraction pattern of the NH4V3O8 electrode material prepared in Example 1 of the present invention is shown.

[0023] Figure 3 The image shows a SEM image of the NH4V3O8 electrode material prepared in Example 1 of the present invention;

[0024] Figure 4Another SEM image of the NH4V3O8 electrode material prepared in Example 1 of the present invention is shown;

[0025] Figure 5 The cycle performance test results of the battery assembled using the NH4V3O8 electrode material prepared in Example 1 of the present invention are shown.

[0026] Figure 6 The results of rate testing are shown for a battery assembled using the NH4V3O8 electrode material prepared in Example 1 of this invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0028] It should be noted that all uses of "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two entities or parameters with the same name but different names. It is clear that "first" and "second" are only for the convenience of expression and should not be construed as limiting the embodiments of the present invention. Subsequent embodiments will not explain this in detail.

[0029] refer to Figure 1 This invention proposes a method for preparing sheet-like NH4V3O8 electrode material, comprising the following steps:

[0030] S1, a vanadium-containing solution and an ammonium salt are mixed to obtain a mixed solution;

[0031] S2, adjust the pH of the mixed solution to 4-6, and carry out the precipitation reaction at 20-85℃ to obtain slurry;

[0032] S3. A morphology modifier is added to the slurry, and the reaction is carried out at a temperature of 90~100℃ to obtain the reacted material. The reacted material is then post-treated to obtain sheet-like NH4V3O8 electrode material.

[0033] In the technical solution of this invention, the pH of a mixed solution obtained by mixing a vanadium-containing solution and an ammonium salt is first adjusted to 4-6, and a precipitation reaction is carried out at a low temperature of 20-85°C to obtain a slurry containing a precipitate. The vanadium in the precipitate exists in the form of decavanadate. Then, a morphology modifier is added to the slurry, and the slurry is heated to 90-100°C. At this time, the vanadate groups are depolymerized under weakly acidic conditions, transforming from high-polymerization-degree decavanadate to low-polymerization-degree trivanadate. Under the action of the morphology modifier, the growth of specific crystal faces is selectively guided by controlling the depolymerization rate, thereby achieving morphology self-assembly and finally obtaining a sheet-like NH4V3O8 electrode material. The sheet-like morphology can provide a huge specific surface area to increase active sites and significantly improve capacity; its nanoscale thickness greatly shortens the ion diffusion path, giving the electrode excellent fast charge and discharge capabilities; at the same time, the sheet structure can effectively alleviate volume changes during charge and discharge, improving cycle stability. These characteristics work together to give the electrode the potential for high capacity, high power, and long life. Sheet-like materials, with their extremely high specific surface area, hold great promise for providing high capacity and constructing dense electrodes, especially suitable for compact devices and micro-energy storage elements that require high energy density. Furthermore, highly polymerized vanadate ions (such as decavanadate) have larger molecular sizes and more complex spatial configurations, with more coordinate-unsaturated vanadium-oxygen bonds on their surfaces. This allows them to adsorb a larger amount of impurity ions through stronger electrostatic interactions and more coordination exchange sites. In contrast, low-polymerized vanadate ions can form pure ammonium vanadate salts and adsorb fewer impurity ions. Therefore, the method of this invention can not only prepare sheet-like NH4V3O8 electrode materials but also effectively improve material purity. In some embodiments, the NH4V3O8 electrode materials prepared by this invention have a purity greater than 99.5%, with the content of key impurities (such as Si, Cr, P, etc.) strictly controlled below 0.005%. The NH4V3O8 electrode materials exhibit high crystallinity and a uniform sheet-like microstructure. NH4V3O8 electrode material has excellent electrochemical performance, and batteries assembled using it as a cathode material exhibit excellent cycle performance and rate performance.

[0034] In some embodiments, the vanadium-containing solution contains pentavalent vanadium, and under weakly acidic conditions, the vanadium in the vanadium-containing solution is mainly in the form of decavanadate (V1vanadate). 10 O 28 6-Vanadium exists in polymeric form. The vanadium-containing solution can be selected from at least one of the following: vanadium nitride solution obtained by sodium roasting-water leaching process, vanadium calcide solution obtained by calcification roasting-acid leaching process, and vanadium extraction solution from coal shale. Of course, the present invention is not limited to this, and other suitable vanadium-containing solutions can also be selected. The sodium roasting-water leaching process may include: mixing vanadium-containing materials (such as vanadium-titanium magnetite, vanadium slag, petroleum coke ash, etc.) with sodium salts (such as sodium carbonate, sodium sulfate, or sodium chloride), roasting at a high temperature (e.g., 750~850℃) to oxidize the insoluble low-valent vanadium in the vanadium-containing materials and convert it into water-soluble high-valent sodium vanadate; then leaching the roasted clinker with water, so that the soluble sodium vanadate salt enters the solution and is separated from most of the insoluble solid residue, and the leachate obtained after filtration is the vanadium nitride solution. The calcination-roasting-acid leaching process may include: mixing vanadium-containing materials (such as vanadium-titanium magnetite, vanadium slag, vanadium-containing coal shale, etc.) with calcium salts (such as CaO or CaCO3), roasting at high temperature (e.g., 800~950℃) to convert vanadium into acid-soluble calcium metavanadate (Ca(VO3)2), etc., and then leaching with an acid solution (e.g., dilute sulfuric acid, carbonic acid) to allow vanadium to enter the solution in ionic form, resulting in vanadium calcination solution. Vanadium extraction extract from coal shale can be a vanadium-containing extract obtained by selectively extracting vanadium from coal shale using a specific extractant.

[0035] In some embodiments, the ammonium salt is selected from at least one of the following: ammonium sulfate, ammonium carbonate, ammonium bicarbonate, ammonium chloride, monoammonium hydrogen phosphate, diammonium hydrogen phosphate, ammonia water, and of course other suitable ammonium-containing inorganic compounds may also be selected.

[0036] In some embodiments, the morphology modifier is selected from at least one of the following: hexadecyltrimethylammonium bromide (CTAB) and dodecylbenzene sulfonate (e.g., sodium dodecylbenzene sulfonate (SDBS)).

[0037] In step S1, solid ammonium salt can be added to the vanadium-containing solution and stirred until the solid ammonium salt is completely dissolved in the vanadium-containing solution to obtain a mixed solution, or ammonia water can be added to the vanadium-containing solution and stirred until the two are mixed evenly to obtain a mixed solution. In some embodiments, in step S1, the vanadium-containing solution and ammonium salt can be mixed in a molar ratio n(NH4) + The mixture is carried out with a molar ratio of n(NH4) = (0.6~2.3):1. Preferably, the mixture is prepared according to a molar ratio of n(NH4) = n(V) = (0.6~2.3):1. + Mix :n(V)=(0.8~1.2):1. Too low an ammonium addition coefficient will result in low vanadium precipitation rate, while too high an ammonium addition coefficient will result in high ammonium salt loss, large ammonia nitrogen wastewater treatment volume, and high production cost.

[0038] In step S2, the temperature of the mixed solution is maintained at 20-85°C, preferably 25-35°C. In step S2, the pH of the mixed solution is adjusted to 4-6, preferably 5-5.5. Lower or higher pH values ​​will decrease the vanadium yield. Under conditions of 20-85°C and pH 4-6, the yield is obtained using decavanadate (V... 10 O 28 6- Vanadium ions, existing in the form of vanadium ions, can rapidly combine with ammonium and sodium ions to form sodium decavanadate (NH4)4Na2V. 10 O 28 The reaction formula is as follows:

[0039]

[0040] In step S2, the sodium decavanadate precipitation reaction is carried out under stirring conditions for 30-120 min, preferably 60 min. If the reaction time is too short, the reaction will not be complete, resulting in a low product yield; if the reaction time is too long, the product yield remains unchanged, but the process energy consumption increases. The slurry obtained after the reaction is not treated and directly proceeds to the next reaction step.

[0041] In step S3, the slurry is kept at a temperature of 90-100℃ (preferably 100℃, where the reaction rate is fast and the product yield is high). Heating in a weakly acidic environment promotes the redistribution of ammonium ions and the release of sodium ions. This causes the vanadate groups to depolymerize and reform, transforming from high-polymerization-degree decavanadate to low-polymerization-degree trivanadate. Simultaneously, a morphology modifier is added to control the depolymerization rate and selectively guide the growth of specific crystal faces, thereby achieving morphology self-assembly and generating a plate-like NH4V3O8 vanadium precipitate. The specific reaction formula is as follows:

[0042]

[0043] In step S3, a morphology modifier is added to the slurry and stirred. In some embodiments, the ratio of the amount of morphology modifier added to the volume of the slurry in step S3 is 0.05~0.5 g / L, preferably 0.1~0.2 g / L. If the amount of morphology modifier is too small, the guiding effect is weak and insufficient to effectively inhibit isotropic crystal growth; if the amount of morphology modifier is too large, it excessively inhibits and hinders the growth of all crystal faces, leading to crystal structure destruction.

[0044] In some embodiments, in step S3, the reaction is carried out under stirring conditions for a reaction time of 60-120 min, preferably 90 min. A shorter reaction time results in incomplete reaction and uneven product morphology; a longer reaction time increases energy consumption. In some embodiments, the post-processing of the reacted material in step S3 includes: filtering the reacted material to obtain vanadium precipitate, and washing and drying the vanadium precipitate to obtain the target flaky NH4V3O8 product.

[0045] In summary, this invention provides a low-temperature, efficient, low-cost, and scalable method for preparing high-purity sheet-like NH4V3O8 electrode materials using vanadium-containing solutions as raw materials. Compared with existing technologies, the method of this invention has the following advantages:

[0046] 1. It enables the low-temperature (90~100℃) large-scale preparation of sheet-like NH4V3O8 electrode materials, which is significantly superior to the traditional hydrothermal method. It eliminates the need for high-temperature and high-pressure equipment, and the process is simple, reproducible, and safe, meeting the needs of industrial production.

[0047] 2. The experimental raw materials are basic primary products in the vanadium industry chain, which significantly reduces costs and has excellent raw material adaptability, laying a solid foundation for large-scale commercialization.

[0048] 3. The resulting sheet electrode material has high crystallinity and consistent morphology. In particular, it has high purity (>99.5%), and the content of key impurities (Si, Cr, P, etc.) is strictly controlled below 0.005%.

[0049] 4. This sheet-like material has excellent electrochemical properties and has broad application prospects in lithium battery cathode materials.

[0050] The following description is based on specific embodiments.

[0051] Example 1

[0052] The vanadium-containing solution used was sodium vanadium brine, which is a vanadium leachate obtained from vanadium slag through sodium roasting and water leaching. It was taken from the Panzhihua Iron and Steel Group Vanadium Products Branch and its main components were: K - 0.239 g / L, Na - 47.22 g / L, Si - 0.86 g / L, Cr - 3.45 g / L, and TV - 47.38 g / L. 200 mL of sodium vanadium brine was measured and 9.81 g of ammonium sulfate was added, i.e., the molar ratio n(NH4+) / ... +The mixture was stirred until ammonium sulfate was completely dissolved to obtain a mixed solution. The pH of the mixed solution was adjusted to 5.5 with sulfuric acid. The reaction was carried out at 20℃ for 30 min, and a slurry was obtained after the reaction was completed. Hexadecyltrimethylammonium bromide was added to the slurry, with the ratio of the amount of hexadecyltrimethylammonium bromide added to the volume of the slurry being 0.05 g / L. The mixture was stirred continuously at 96℃ for 60 min. After the reaction was completed, the vanadium precipitate was obtained by filtration. The vanadium precipitate was washed twice with deionized water, filtered, and dried to obtain flake-like NH4V3O8. The purity of NH4V3O8 was tested to be 99.65%, and the content of each impurity element by mass percentage was: K-0.022%, Na-0.0051%, Si-0.0011%, Cr-0.0038%.

[0053] XRD analysis was performed on the NH4V3O8 obtained in Example 1, and the resulting X-ray diffraction pattern is shown below. Figure 2 As shown, this indicates that the product is a pure phase substance with high crystallinity.

[0054] The NH4V3O8 obtained in Example 1 was subjected to SEM testing, and the obtained SEM image is shown below. Figure 3 and Figure 4 As shown, the product is a sheet-like material with a uniform morphology.

[0055] Coin cells were assembled using NH4V3O8 obtained in Example 1 as the positive electrode material, and the assembled cells were subjected to cycle performance and rate testing. The assembly method for the coin cells included: mixing the NH4V3O8 active material with the conductive agent Super-P and the binder PVDF in a mass ratio of 7:2:1 in NMP solvent; and coating the mixture onto aluminum foil (area loading 2.5~4.0 mg / cm³). 2 After drying, cutting, and rolling, the material was stored in an argon glove box to obtain the electrode. Using this electrode as the positive electrode, lithium metal as the negative electrode, Celgard 2400 as the separator, and 1.0M LiPF6 dissolved in an EC:DMC:EMC (mass ratio 1:1:1) mixture as the electrolyte, a CR2025 coin cell was assembled. Cyclic performance testing methods included: activating the coin cell three times at 30 mA / g, followed by constant current charge-discharge cycling at 300 mA / g (1.5~4.0V). Rate testing methods included: cycling five times each at current densities of 30, 90, 150, 300, 600, and 1000 mA / g, and finally restoring to 30 mA / g for cycling.

[0056] Figure 5The results of the cycle performance test show that the battery has excellent cycle performance. The initial capacity at a current density of 300 mA / g is 213.8 mAh / g, and the specific capacity is still 187.5 mAh / g after 300 cycles, with a capacity retention rate of 87.7%.

[0057] Figure 6 The rate test results show that the battery has excellent rate performance. When the current density is 30mA / g, 90mA / g, 150mA / g, 300mA / g, 600mA / g, and 1000mA / g, the discharge specific capacities are 419.5mAh / g, 274.9mAh / g, 219.7mAh / g, 159.6mAh / g, 89.8mAh / g, and 54.4mAh / g, respectively. When the current density returns to 30mA / g, the battery still has a specific capacity of 296.9mAh / g.

[0058] Example 2

[0059] The vanadium-containing solution used was the extract from the vanadium extraction process of coal shale, with the main components being: Al - 13.88 g / L, Fe - 5.09 g / L, K - 5.81 g / L, Mg - 3.72 g / L, P - 0.51 g / L, and TV - 1.89 g / L. 2000 mL of the extract was measured, and 7.93 g of ammonium chloride was added, i.e., the molar ratio n(NH4) + The mixture was stirred until ammonium chloride was completely dissolved to obtain a mixed solution. The pH of the mixed solution was adjusted to 5.0 using sodium hydroxide. The reaction was carried out at 40℃ for 60 min, and a slurry was obtained after the reaction was completed. Hexadecyltrimethylammonium bromide was added to the slurry, with the ratio of the amount of hexadecyltrimethylammonium bromide added to the volume of the slurry being 0.1 g / L. The mixture was stirred continuously at 94℃ for 90 min. After the reaction was completed, the vanadium precipitate was obtained by filtration. The vanadium precipitate was washed twice with deionized water, filtered, and dried to obtain the target product of flaky NH4V3O8. The purity of NH4V3O8 was tested to be 99.81%, and the content of each impurity element by mass percentage was: Fe-0.022%, Al-0.017%, K-0.024%, Mg-0.002%, P-0.001%. The coin cells were assembled and electrochemical performance was tested using the same method as in Example 1. The test results showed that after 300 cycles at a current density of 300 mA / g, the capacity retention was 86.3%, and the cells exhibited excellent rate performance.

[0060] Example 3

[0061] The vanadium-containing solution used was vanadium calcification solution, which is a vanadium leachate obtained from vanadium slag through calcification roasting and acid leaching. It was sourced from Panzhihua Iron & Steel Group Xichang Vanadium Products Technology Co., Ltd., and its main components were: Na - 0.477 g / L, Ca - 0.442 g / L, Si - 0.116 g / L, Mn - 6.29 g / L, Mg - 1.47 g / L, and TV - 25.44 g / L. 200 mL of vanadium calcification solution was measured, and 5.09 g of ammonium carbonate (AR grade, containing 40 wt% NH3) was added, i.e., the molar ratio n(NH4+) / (NH4+) = 1.09 g / L. + The ratio of sodium dodecylbenzenesulfonate to sodium vanadate was approximately 1.2:1. The mixture was stirred until ammonium carbonate was completely dissolved to obtain a mixed solution. The pH of the mixed solution was adjusted to 6.0 using sodium hydroxide. The reaction was carried out at 60℃ for 90 min, and a slurry was obtained after the reaction was completed. Sodium dodecylbenzenesulfonate was added to the slurry, with the ratio of sodium dodecylbenzenesulfonate added to the slurry volume being 0.2 g / L. The mixture was stirred continuously at 90℃ for 120 min. After the reaction was completed, the vanadium precipitate was obtained by filtration. The vanadium precipitate was washed twice with deionized water, filtered, and dried to obtain the target product, flaky NH4V3O8. The purity of NH4V3O8 was tested to be 99.75%, and the content of each impurity element by mass percentage was: Na - 0.0033%, Si - 0.0046%, Ca - 0.0015%, Mn - 0.019%, Mg - 0.0093%. The coin cells were assembled and electrochemical performance was tested using the same method as in Example 1. The test results showed that after 300 cycles at a current density of 300 mA / g, the capacity retention was 88.4%, and the cells exhibited excellent rate performance.

[0062] Example 4

[0063] The vanadium-containing solution used was a high-chromium vanadium solution, with the main components being: Cr - 4.39 g / L, Si - 2.04 g / L, Fe - 1.12 g / L, P - 0.63 g / L, and TV - 72.21 g / L. 200 mL of the high-chromium vanadium solution was measured, and 13.13 g of ammonium bicarbonate (AR grade, containing 22 wt% NH3) was added, i.e., the molar ratio n(NH4+) +The ratio of ammonium bicarbonate to vanadium is approximately 0.6:1. The mixture is stirred until completely dissolved to obtain a mixed solution. The pH of the mixed solution is adjusted to 4.0 using sulfuric acid. The reaction is carried out at 85℃ for 120 min, and a slurry is obtained after the reaction is complete. Sodium dodecylbenzenesulfonate is added to the slurry at a ratio of 0.5 g / L to the slurry volume. The mixture is stirred continuously at 100℃ for 30 min. After the reaction is complete, the vanadium precipitate is obtained by filtration. The vanadium precipitate is washed twice with deionized water, filtered, and dried to obtain the target product, flaky NH4V3O8. The purity of NH4V3O8 is 99.63%, and the content of each impurity element by mass percentage is: Cr - 0.0035%, Si - 0.0047%, Fe - 0.0019%, P - 0.0022%. The coin cells were assembled and electrochemical performance was tested using the same method as in Example 1. The test results showed that after 300 cycles at a current density of 300 mA / g, the capacity retention was 87.7%, and the cells exhibited excellent rate performance.

[0064] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of the different aspects of the invention as described above exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for preparing a sheet-like NH4V3O8 electrode material, characterized by, The method comprises the following steps: S1, mixing a vanadium-containing solution and an ammonium salt to obtain a mixed solution; S2, adjusting the pH of the mixed solution to 4-6, and performing a precipitation reaction at 20-85 DEG C to obtain a slurry; S3, adding a morphology adjusting agent to the slurry, and performing a reaction at a temperature of 90-100 DEG C to obtain a post-reaction material, and performing post-treatment on the post-reaction material to obtain the flaky NH4V3O8 electrode material; The vanadium-containing solution is selected from at least one of the following: a sodiumized vanadium solution obtained by a sodiumization roasting-water leaching process, a calcified vanadium solution obtained by a calcification roasting-acid leaching process, and a stone coal vanadium extraction solution; and the morphology adjusting agent is selected from at least one of the following: cetyltrimethylammonium bromide and dodecylbenzenesulfonate.

2. The method of claim 1, wherein, The vanadium-containing solution contains pentavalent vanadium.

3. The method of claim 1, wherein, The ammonium salt is selected from at least one of the following: ammonium sulfate, ammonium carbonate, ammonium bicarbonate, ammonium chloride, monoammonium phosphate, diammonium hydrogen phosphate, and ammonia.

4. The method of claim 1, wherein, In step S1, the vanadium-containing solution and the ammonium salt are mixed in a molar ratio n(NH4 + ):n(V)=(0.6~2.3):

1.

5. The method of claim 1, wherein, In step S2, the reaction time is 30-120 min.

6. The method of claim 1, wherein, In step S3, the ratio of the amount of the morphology adjusting agent to the volume of the slurry is 0.05-0.5 g / L, the reaction is performed under stirring, and the reaction time is 60-120 min.

7. The method of claim 1, wherein, In step S3, the post-treatment of the post-reaction material comprises: filtering the post-reaction material to obtain a vanadium precipitation product, and washing and drying the vanadium precipitation product.

8. A plate-like NH4V3O8 electrode material, characterized by, The flaky NH4V3O8 electrode material prepared by the method of any one of claims 1-7 has a purity of greater than 99.5% and a flaky micro-morphology.

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