In-situ surface-coated vanadate composite materials, their preparation methods and applications

Abstract

This invention relates to the field of nanomaterials technology, and discloses a vanadate composite material, its preparation method, and its application. A reaction solution containing a surfactant is prepared to generate bubbles. These bubbles then act as soft templates under rapid stirring and heating. Vanadium oxide is dispersed in this reaction solution and reacted at a specific temperature for a certain time, allowing the surfactant to intercalate the vanadium oxide, transforming it into vanadate. The surfactant then coats the outer surface of the vanadate, resulting in an in-situ surface-modified vanadate composite material. The surfactant layer of this composite material can regulate the reaction layer between the electrode surface and the electrolyte, preventing electrode material dissolution or structural collapse during the electrochemical reaction process, thus significantly improving the performance of electrochemical energy storage devices. The foaming effect of the surfactant ensures that the bubbles are uniformly dispersed in the liquid, acting as soft templates for the attachment and growth of vanadate crystals.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials technology, and in particular to an in-situ surface-coated vanadate composite material, its preparation method, and its application. Background Technology

[0002] Aqueous zinc-ion batteries represent a new generation of environmentally friendly rechargeable secondary battery systems. They are highly attractive due to their advantages, including using high-capacity zinc metal directly as the electrode material, employing safer and lower-cost aqueous electrolytes, and having less stringent environmental requirements during manufacturing. However, zinc-based aqueous energy storage devices still face many scientific challenges requiring further research and numerous problems that need to be solved. One of the most significant challenges is that the active material in the aqueous electrolyte gradually dissolves due to limitations in conductivity and structural stability, as well as crystal structure transformations, leading to a gradual capacity decay during cycling.

[0003] Currently, the most widely studied and relatively high-performing cathode materials for aqueous zinc-ion batteries are vanadium-based oxides with intercalation storage mechanisms and manganese-based oxides with reversible phase-change storage mechanisms. The layered crystal structure of vanadium oxides allows for efficient zinc ion insertion due to its large interlayer spacing; therefore, metal vanadates and their derivatives containing structured water molecules have attracted considerable attention. However, the high solubility of vanadium in aqueous electrolytes in metal vanadates leads to rapid capacity decay during battery cycling.

[0004] To suppress the continuous dissolution of manganese or vanadium in the active material in aqueous electrolytes, a simple modification method is to pre-add a certain amount of the corresponding metal ions to the aqueous electrolyte, thereby improving the stability of the electrode to some extent. Furthermore, researchers have recognized that surface modification can slow down the gradual dissolution of electrode materials. For example, some literature reports that coating the surface of MnO2 with the conductive polymer poly(3,4-dioxanethiophene) (PEDOT), along with the combined effect of MnSO4 electrolyte additives, can effectively improve the cycle performance of Zn-MnO2 batteries (Adv Mater, 2017, 29(26): 1700-274). Similarly, uniformly coating 5-nanometer diameter α-MnO2 nanorods with graphene rolls, along with the combined effect of MnSO4 electrolyte additives, can effectively suppress the dissolution of Mn (Small, 2018, 14(13): 170-3850).

[0005] While the above methods utilize electrolyte additives to jointly suppress the dissolution of electrode materials, further research is needed to address the challenge of metal element dissolution from the perspective of the electrode material itself. This technology primarily targets the surface modification of vanadate cathode materials. During the synthesis of cathode materials, in-situ surface modification and coating are performed on the cathode material, simplifying the material modification steps.

[0006] In existing technologies, the preparation of vanadate composite materials typically employs a two-step method: the steps usually involve first synthesizing vanadate, and then modifying, coating, or altering the vanadate using some method to obtain the vanadate composite material. These processes include repeated washing and drying treatments, and the modification, coating, or alteration processes may cause irreversible changes in the structure, morphology, and physical properties of the vanadate precursor.

[0007] Technical problems with existing technologies:

[0008] 1. Reaction conditions are not easy to control: The above preparation method involves complicated and lengthy steps, and the reaction conditions (such as reaction time and reaction temperature) of multiple steps are not easy to control precisely, which will affect the performance of the final product.

[0009] 2. Unstable product performance: Due to the difficulty in controlling the reaction conditions, the properties of the obtained vanadate composite materials vary greatly, which affects their performance stability in practical applications.

[0010] 3. Complex reaction process: Traditional preparation methods require multiple washing and drying processes, which not only increases the complexity of the preparation process but also increases the preparation cost.

[0011] 4. Environmental impact: Traditional preparation methods use a variety of different reactants, which has a certain impact on the environment. At the same time, some wastes that are harmful to the environment are also generated during the reaction process. Summary of the Invention

[0012] In view of the shortcomings of the prior art, the purpose of this invention is to provide an in-situ surface-coated vanadate composite material, its preparation method and application, in order to solve the problem of gradual degradation of electrochemical performance when vanadates are used as electrode materials.

[0013] The technical solution of the present invention is as follows:

[0014] A method for preparing an in-situ surface-coated vanadate composite material, comprising the steps of:

[0015] Prepare a reaction solution containing a certain concentration of surfactant, and use shaking or ultrasound to generate a large number of bubbles in the surfactant reaction solution;

[0016] The foaming surfactant reaction solution is heated while being rapidly stirred, so that the bubbles serve as a soft template for the reaction.

[0017] A certain amount of vanadium oxide is dispersed in a surfactant reaction solution and reacted at a specific temperature for a certain time to allow the surfactant to fully intercalate the vanadium oxide, converting the vanadium oxide into vanadate. At the same time, the vanadate is coated onto the outer surface of the vanadate for surface modification, resulting in an in-situ surface-coated vanadate composite material.

[0018] Optionally, the surfactant includes, but is not limited to, one or more of sodium linear alkylbenzene sulfonate, sodium linear alkyl sulfate, sodium stearate, sodium docusate, and hexadecyltrimethylammonium bromide.

[0019] Optionally, the amount of surfactant of a certain concentration is between 0.1 mol / L and 1.0 mol / L.

[0020] Optionally, the amount of vanadium oxide used is related to the concentration of the surfactant, and the molar ratio of vanadium oxide to surfactant is between 1:1 and 1:10.

[0021] Optionally, the intercalation reaction temperature is between 55 and 95°C.

[0022] Optionally, the intercalation reaction time is related to the reaction temperature and is generally between 24 and 72 hours.

[0023] An in-situ surface-coated vanadate composite material, wherein the in-situ surface-coated vanadate composite material is prepared by the preparation method of the in-situ surface-coated vanadate composite material described in this invention.

[0024] The in-situ surface-coated vanadate composite material described in this invention has been used as an electrode material in aqueous energy storage devices.

[0025] The present invention has the following beneficial effects:

[0026] First, the present invention provides a vanadate composite material with an in-situ surface-coated surfactant layer. This microstructure is beneficial for regulating the solid-liquid reaction layer between the solid electrode surface and the electrolyte, avoiding the dissolution or structural collapse of the electrode material during the electrochemical reaction process, thereby improving the electrochemical stability of the electrode material.

[0027] This invention utilizes the foaming effect of surfactants. Surfactant molecules can be adsorbed on the gas-liquid interface of the bubble surface and oriented to form a strong film, so that the bubble is uniformly dispersed in the liquid, thereby serving as a soft template for vanadate crystals to attach and grow.

[0028] In this invention, the surfactant serves both as a reactant in the vanadium oxide intercalation reaction and as a coating layer for the vanadate product. During the reaction, the surface of the product is simultaneously modified in situ to obtain a surface-modified vanadate composite material.

[0029] The preparation process of this invention is simple, the selected reactants are multi-purpose, and the reaction steps are combined into one, which conforms to the concepts of atom economy and green chemistry, and is green, environmentally friendly and safe. The reaction conditions of this invention are readily available, the applicable objects are wide, and it is easy to prepare on a large scale: the selection of preparation conditions is not very demanding, and can be flexibly adjusted within a large range, such as temperature range, reaction time and reaction solution concentration, which is conducive to subsequent scale-up production and industrialization.

[0030] Secondly, the present invention uses bubbles as soft templates, and the generation and growth of vanadates are carried out on the template surface, so that the resulting vanadate composite material has a uniform microstructure and excellent surface properties, which significantly improves the performance and stability of the composite material.

[0031] The use of various surfactants in this invention enriches the types and choices of surfactants, allowing for the selection of the most suitable surfactant as needed, making the reaction more flexible and diversified, and facilitating further optimization of the composite material's performance.

[0032] The ratio and concentration of surfactant and vanadium oxide in this invention are precisely controlled, making the reaction more accurate and conducive to obtaining high-quality vanadate composite materials. It also facilitates the large-scale and industrialization of the reaction.

[0033] The intercalation reaction temperature and reaction time settings of this invention allow the intercalation reaction to proceed under optimal conditions, which is beneficial for improving the yield and quality of vanadates, while also reducing production costs.

[0034] Because the present invention employs the method described in any one of claims 1 to 4, the composite material exhibits excellent electrochemical properties, which is beneficial for improving the performance and efficiency of energy storage devices.

[0035] The application of the composite material of the present invention in water-based energy storage devices helps to achieve efficient, stable, and long-life operation of the energy storage devices, and significantly improves the overall performance of the energy storage devices.

[0036] The preparation method of this invention generates a large number of bubbles through oscillation or ultrasound, which makes the reaction more uniform and is beneficial to improving the reaction efficiency and the yield of vanadate.

[0037] The preparation method of the present invention uses bubbles as a soft template for the reaction, which is beneficial to achieve uniform generation and growth of vanadate, thereby improving the quality and performance of the composite material.

[0038] This invention transforms vanadium oxide into vanadate through intercalation, resulting in a composite material with excellent stability and electrochemical performance, which significantly improves the performance of energy storage devices.

[0039] This invention improves the surface properties of composite materials by coating the outer surface of vanadate with surfactants, thereby enhancing the performance of the composite materials in energy storage devices and contributing to the efficient operation of energy storage devices. Attached Figure Description

[0040] Figure 1 This is a scanning electron microscope image of the in-situ surface-coated and modified vanadate composite material prepared in Example 1;

[0041] Figure 2 This is an X-ray diffraction pattern of the in-situ surface-coated vanadate composite material prepared in Example 1;

[0042] Figure 3 This is a cycle performance diagram of the in-situ surface-coated vanadate composite material prepared in Example 1 as a cathode material for an aqueous zinc-ion battery;

[0043] Figure 4 This is a rate performance diagram of the in-situ surface-coated vanadate composite material prepared in Example 1 as a cathode material for an aqueous zinc-ion battery;

[0044] Figure 5 This is an X-ray diffraction pattern of the in-situ surface-coated vanadate composite material prepared in Example 2;

[0045] Figure 6 This is an X-ray diffraction pattern of the in-situ surface-coated vanadate composite material prepared in Example 3. Detailed Implementation

[0046] This invention provides an in-situ surface-coated vanadate composite material, its preparation method, and its application. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0047] This invention discloses an in-situ surface-coated modified vanadate composite material, its preparation method, and its application. The method includes the following steps: preparing a reaction solution containing a certain concentration of surfactant; generating a large number of bubbles in the surfactant reaction solution by shaking or sonication; rapidly stirring and heating the foaming surfactant reaction solution, using the bubbles as a soft template for the reaction; dispersing a certain amount of vanadium oxide in the surfactant reaction solution; reacting at a specific temperature for a certain time to allow the surfactant to fully intercalate the vanadium oxide, converting the vanadium oxide into vanadate, and simultaneously coating the outer surface of the vanadate for surface modification, thus obtaining the in-situ surface-coated modified vanadate composite material. This composite material of the present invention has an in-situ surface-coated modified surfactant layer, which can regulate the solid-liquid reaction layer between the solid electrode surface and the electrolyte, avoiding electrode material dissolution or structural collapse during the electrochemical reaction process, and greatly contributing to the performance improvement of the overall electrochemical energy storage device. The foaming effect of the surfactant allows surfactant molecules to adsorb onto the gas-liquid interface on the bubble surface, oriented to form a robust film, ensuring uniform dispersion of the bubbles in the liquid, thereby serving as a soft template for the attachment and growth of vanadate crystals.

[0048] The working principle of the method for preparing in-situ surface-coated and modified vanadate composite materials provided by the present invention can be described in detail as follows:

[0049] 1) Preparation of the reaction solution: First, the reaction solution is prepared by mixing a surfactant and a suitable solvent. The surfactant reduces the surface tension of the solution, allowing the reaction solution to generate a large number of bubbles when shaken or sonicated.

[0050] 2) Bubble formation: The bubbles formed in the reaction solution act as soft templates for the reaction. These bubbles can be evenly dispersed in the reaction solution through rapid stirring and heating.

[0051] 3) Vanadium oxide intercalation: Vanadium oxide is dispersed in a reaction solution containing a surfactant. At a specific temperature, vanadium oxide reacts with the surfactant, which intercalates into the interlayer voids of the vanadium oxide. This intercalation structure improves the stability and electrochemical performance of vanadium oxide.

[0052] 4) Surface modification: During the reaction, vanadium oxide is converted into vanadate, and the outer surface of the vanadate is coated with a surfactant. This modification can further improve the stability and electrochemical performance of vanadate.

[0053] Through the above steps, an in-situ surface-coated vanadate composite material can be obtained. Due to its unique structure, this material exhibits excellent electrochemical performance and stability, making it highly suitable for use as an electrode material in energy storage batteries.

[0054] This invention provides a method for preparing in-situ surface-coated vanadate composite materials, comprising:

[0055] First, a reaction solution containing a surfactant is prepared. This reaction solution generates a large number of bubbles by shaking or sonication. After the bubbles form, the reaction solution is rapidly stirred and heated, so that the bubbles act as soft templates for the reaction. On this basis, a certain amount of vanadium oxide is dispersed in the surfactant reaction solution and reacted at a specific temperature for a certain time, so that the surfactant can fully intercalate the vanadium oxide, converting the vanadium oxide into vanadate, and at the same time, the outer surface of the vanadate is coated and modified by the surfactant.

[0056] Surfactants include, but are not limited to, one or more of sodium linear alkylbenzene sulfonate, sodium linear alkyl sulfate, sodium stearate, sodium docusate, and hexadecyltrimethylammonium bromide. These surfactants provide an effective reaction medium, helping to generate uniform and stable bubbles. The concentration of the surfactant is between 0.1 mol / L and 1.0 mol / L, a concentration range that is conducive to the generation of a uniform bubble template. Simultaneously, a certain amount of vanadium oxide to surfactant molar ratio between 1:1 and 1:10 is beneficial to the conversion of vanadium oxide and the formation of vanadates.

[0057] The intercalation reaction temperature is between 55 and 95°C, which is conducive to the intercalation reaction of surfactants. The intercalation reaction time is related to the reaction temperature and is generally between 24 and 72 hours. This time range is conducive to the full progress of the reaction and the obtaining of high-quality vanadate composite materials.

[0058] The in-situ surface-coated vanadate composite material provided by this invention, prepared by the method provided by this invention, exhibits excellent electrochemical properties and can effectively improve the performance of energy storage devices. This composite material can be used as an electrode material in aqueous energy storage devices, and due to its in-situ surface-coated modification characteristics, it can improve the stability and service life of the equipment.

[0059] The reaction solution generates a large number of bubbles through agitation or sonication. These bubbles serve as soft templates for the reaction, facilitating the formation and growth of vanadates. The bubbles, acting as soft templates, promote the conversion of vanadium oxide and the formation of vanadates, as well as the effective coating of surfactants. Vanadium oxide is transformed into vanadates through surfactant intercalation, a process that helps improve the stability and electrochemical performance of the vanadate composite material. The outer surface of the vanadate is coated with surfactants, a modification process that improves the surface properties of the composite material and enhances its performance in electrode applications.

[0060] This invention provides a method for preparing an in-situ surface-coated vanadate composite material, comprising the following steps:

[0061] S1. Prepare a reaction solution containing a certain concentration of surfactant, and use shaking or ultrasound to generate a large number of bubbles in the surfactant reaction solution;

[0062] S2. The foaming surfactant reaction solution is heated while being rapidly stirred, so that the bubbles serve as a soft template for the reaction.

[0063] S3. A certain amount of vanadium oxide is dispersed in a surfactant reaction solution and reacted at a specific temperature for a certain time to allow the surfactant to fully intercalate the vanadium oxide, converting the vanadium oxide into vanadate, and simultaneously coating the outer surface of the vanadate for surface modification, thus obtaining an in-situ surface-coated vanadate composite material.

[0064] In this embodiment, a reaction solution containing a certain concentration of surfactant is first prepared. A large number of bubbles are generated in the surfactant reaction solution by shaking or sonication. Then, the foaming surfactant reaction solution is rapidly stirred and heated, using the bubbles as a soft template for the reaction. Finally, a certain amount of vanadium oxide is dispersed in the surfactant reaction solution and reacted at a specific temperature for a certain time, allowing the surfactant to fully intercalate the vanadium oxide, converting it into vanadate. Simultaneously, the surfactant coats the outer surface of the vanadate for surface modification, resulting in an in-situ surface-modified vanadate composite material. Compared with conventionally prepared vanadates, the in-situ surface-modified vanadate composite material (as an electrode material) prepared in this embodiment has an in-situ surface-modified surfactant layer. This is beneficial for regulating the solid-liquid reaction layer between the solid electrode surface and the electrolyte, preventing electrode material dissolution or structural collapse during the electrochemical reaction process, thereby improving the electrochemical stability of the electrode material. Simultaneously, utilizing the foaming effect of the surfactant, surfactant molecules can adsorb onto the gas-liquid interface on the bubble surface, oriented to form a robust film, allowing the bubbles to be uniformly dispersed in the liquid, thus serving as a soft template for the attachment and growth of vanadate crystals. It is worth mentioning that the surfactant serves both as a reactant in the vanadium oxide intercalation reaction and as a coating layer for the vanadate product. During the reaction, the surface of the product is modified in situ, resulting in a surface-modified vanadate composite material.

[0065] The in-situ surface-coated vanadate composite material prepared by the method in this embodiment can be applied in electrochemical and energy storage fields such as aqueous energy storage devices. Furthermore, the preparation process of this embodiment is simple, the reaction conditions are readily available, it has a wide range of applications, is safe and environmentally friendly, and is easy to prepare on a large scale, thus possessing broad application prospects.

[0066] In step S1, in one embodiment, the reaction solution containing a certain concentration of surfactant is prepared by the following method: a surfactant (one or more of sodium linear alkylbenzene sulfonate, sodium linear alkyl sulfate, sodium stearate, sodium docusate, and hexadecyltrimethylammonium bromide) is dissolved in an aqueous solution, and the reaction solution is subjected to shaking or ultrasonication to generate a large number of bubbles, thus obtaining the reaction solution containing a certain concentration of surfactant; wherein the amount of surfactant is between 0.1 mol / L and 1.0 mol / L. At the selected molar concentration, the prepared reaction solution has moderate viscosity and tension, making it easy to foam, coat, and intercalate into the vanadium oxide lattice.

[0067] In step S2, in one embodiment, the foaming surfactant reaction solution is rapidly stirred and heated, allowing the bubbles to act as soft templates for the reaction. The heating temperature is controlled between 55 and 95°C to prepare for the subsequent intercalation reaction; the stirring speed is controlled between 500 and 2000 rpm. The intercalation reaction is highly sensitive to heating temperature; if the temperature does not reach the trigger temperature, the reaction cannot proceed even with extended reaction time. A certain stirring speed ensures that the foaming effect of the surfactant continues, allowing the bubbles to be uniformly dispersed in the liquid, thus serving as soft templates for the attachment and growth of vanadate crystals.

[0068] In step S3, in one embodiment, a certain amount of vanadium oxide is dispersed in a surfactant reaction solution and reacted at a specific temperature for a certain time to allow the surfactant to fully intercalate the vanadium oxide, converting it into vanadate. Simultaneously, the vanadate is coated onto the outer surface of the vanadate for surface modification, resulting in an in-situ surface-coated vanadate composite material. The amount of vanadium oxide is related to the concentration of the surfactant, with a molar ratio of vanadium oxide to surfactant between 1:1 and 1:10. The intercalation reaction temperature is between 55 and 95°C, and the intercalation reaction time is related to the reaction temperature, generally between 24 and 72 hours. By adjusting the molar ratio of vanadium oxide to surfactant, the intercalation reaction is ensured to proceed fully, and the coating thickness is selected according to the surface modification requirements. If the surfactant concentration is too low, the intercalation reaction will be incomplete; if the surfactant concentration is too high, the solution viscosity will be too high, forming a gel upon heating, making rapid stirring impossible.

[0069] This invention provides an in-situ surface-coated vanadate composite material, wherein the in-situ surface-coated vanadate composite material is prepared using the in-situ surface-coated vanadate composite material preparation method described in this invention.

[0070] The in-situ surface-coated vanadate composite material described in this embodiment is used as an electrode material in an aqueous energy storage device.

[0071] The present invention will be further described below through specific embodiments.

[0072] Example 1

[0073] The method for preparing in-situ surface-coated vanadate composite materials using sodium dodecyl sulfate (SDS) as a surfactant is as follows:

[0074] First, 2.0 mmol of sodium dodecyl sulfate was dissolved in 10 mL of deionized water. After sonication / vibration for 10 min, the surfactant reaction solution was placed in a water bath and heated to 90 °C. Then, 1.0 mmol of V₂O₅ was weighed and dispersed in the surfactant reaction solution with stirring. The reaction was kept at 90 °C for 48 h with stirring at 1000 rpm throughout. Finally, the product was collected by high-speed centrifugation and dried in a vacuum oven at 60 °C for 12 h to obtain the product.

[0075] Figure 1 This is a scanning electron microscope (SEM) image of the in-situ surface-coated vanadate composite material prepared in this embodiment. Figure 1 As can be seen, the vanadate prepared in this embodiment exhibits the morphology of nanowires, and the surface of the vanadate is successfully coated with an organic material.

[0076] Figure 2 This is the X-ray diffraction pattern of the in-situ surface-coated vanadate composite material prepared in this embodiment. Figure 2 It can be seen that the overall phase of the obtained vanadate composite material is HNaV6O. 16 ·4H2O (JCPDS card number 490996). Due to the thin coating layer, the diffraction peaks of the surfactant are not shown in the figure.

[0077] Figure 3 This is a cycle performance diagram of the in-situ surface-coated vanadate composite material prepared in this embodiment as a cathode material for an aqueous zinc-ion battery. Figure 3 It can be seen that battery devices made using this in-situ surface-coated vanadate composite material as the electrode material have good cycle stability.

[0078] Figure 4 This is a rate performance diagram of the in-situ surface-coated vanadate composite material prepared in this embodiment as a cathode material for aqueous zinc-ion batteries. Figure 4 It can be seen that the battery devices made with this in-situ surface-coated vanadate composite material as the electrode material have good rate performance and still have stable specific capacity under high current charging and discharging.

[0079] Example 2

[0080] The difference between this embodiment and Example 1 is that cetyltrimethylammonium bromide (CTAB) was used as the surfactant; 10.0 mmol of cetyltrimethylammonium bromide was weighed and dissolved in 10 mL of deionized water; and the reaction was carried out at 90°C for 72 h. Other steps and parameters were the same as in Example 1.

[0081] Figure 5 This is an X-ray diffraction pattern of the in-situ surface-coated vanadate composite material prepared in this embodiment. From... Figure 5 It can be seen that the overall phase of the obtained vanadate composite material is very similar to vanadium oxide V₂O₅·6H₂O with crystallization water (JCPDS card number 450401), which is a new phase formed after the insertion of surfactant between the layers of V₂O₅. Due to the thick coating layer, the diffraction peaks of the surfactant are also shown in the figure.

[0082] Example 3

[0083] The difference between this embodiment and Example 1 is that sodium dodecylbenzenesulfonate (SDBS) was used as the surfactant; 1.0 mmol of sodium dodecylbenzenesulfonate was weighed and dissolved in 10 mL of deionized water; and the reaction was carried out at 90°C for 24 h. Other steps and parameters were the same as in Example 1.

[0084] Figure 6 This is the X-ray diffraction pattern of the in-situ surface-coated vanadate composite material prepared in this embodiment. Figure 6 It can be seen that the overall phase of the vanadate composite material obtained similarly to that in Example 1 is HNaV6O. 16 ·4H2O (JCPDS card number 490996) also does not show diffraction peaks for the surfactant in the figure. However, unlike Example 1, the vanadate obtained by sodium dodecylbenzenesulfonate intercalation has higher crystallinity, and therefore the diffraction peaks are stronger.

[0085] In summary, this invention provides an in-situ surface-coated modified vanadate composite material, its preparation method, and its applications. The in-situ surface-coated modified vanadate composite material prepared by this invention has an in-situ surface-coated surfactant layer. This microstructure is beneficial for regulating the solid-liquid reaction layer between the solid electrode surface and the electrolyte, preventing electrode material dissolution or structural collapse during the electrochemical reaction process, thereby improving the electrochemical stability of the electrode material. Simultaneously, utilizing the foaming effect of the surfactant, surfactant molecules can adsorb onto the gas-liquid interface of the bubble surface, oriented to form a robust film, allowing the bubbles to be uniformly dispersed in the liquid, thus serving as a soft template for vanadate crystal attachment and growth. It is worth mentioning that the surfactant acts both as a reactant in the vanadium oxide intercalation reaction and as a coating layer for the vanadate product, simultaneously modifying the product's surface in situ during the reaction to obtain the surface-coated modified vanadate composite material. The in-situ surface-coated modified vanadate composite material of this invention can be applied in electrochemical and energy storage fields such as aqueous energy storage devices. Furthermore, the preparation process of this invention is simple, the selected reactants are multi-purpose, and the reaction steps are combined into one, which conforms to the concepts of atom economy and green chemistry, and is green, environmentally friendly and safe. The reaction conditions of this invention are readily available, it has a wide range of applications, and it is easy to prepare on a large scale, which is conducive to subsequent scale-up production and industrialization, and has broad application prospects.

[0086] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing in-situ surface-coat-modified vanadate composites, characterized by, First, a reaction solution containing a surfactant is prepared. This reaction solution generates a large number of bubbles by shaking or sonication. After the bubbles are formed, the reaction solution is rapidly stirred and heated so that the bubbles act as a soft template for the reaction. On this basis, a certain amount of vanadium oxide is dispersed in the surfactant reaction solution and reacted at a specific temperature for a certain time so that the surfactant can fully intercalate the vanadium oxide, converting the vanadium oxide into vanadate, and at the same time, the outer surface of the vanadate is coated and modified by the surfactant. The concentration of the surfactant is between 0.1 mol / L and 1.0 mol / L; at the same time, the molar ratio of a certain amount of vanadium oxide to the surfactant is between 1:1 and 1:

10. The intercalation reaction temperature is between 55 and 95°C, which is conducive to the intercalation reaction of the surfactant; the intercalation reaction time is related to the reaction temperature and is between 24 and 72 hours.

2. The preparation method according to claim 1, characterized in that, The surfactants mentioned include one or more of sodium linear alkylbenzene sulfonate, sodium linear alkyl sulfate, sodium stearate, sodium docusate, and hexadecyltrimethylammonium bromide. These surfactants can provide an effective reaction medium and help generate uniform and stable bubbles.

3. A vanadate composite material with in-situ surface coating modification, characterized in that, This composite material is prepared by the method described in any one of claims 1-2. This composite material has excellent electrochemical properties and can effectively improve the performance of energy storage devices.

4. The composite material according to claim 3, characterized in that, This composite material can be used as an electrode material in water-based energy storage devices. Due to its in-situ surface coating modification characteristics, it can improve the stability and service life of the equipment.

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