A method for preparing a vanadium selenide-vanadium oxide heterojunction photo-assisted zinc-ion battery

Abstract

This invention relates to a method for preparing a vanadium selenide / vanadium oxide heterojunction photo-assisted zinc-ion battery, belonging to the technical field of vanadium selenide / vanadium oxide heterojunction photo-assisted electrochemical energy storage and zinc-ion battery. The method includes the following steps: mixing a selenium source solution and a vanadium source solution to obtain a reaction precursor solution; subjecting the reaction precursor solution to a hydrothermal reaction and washing to obtain vanadium selenide material; annealing the vanadium selenide material to form a vanadium oxide layer on its surface, obtaining a vanadium selenide / vanadium oxide heterojunction composite material; mixing the vanadium selenide / vanadium oxide heterojunction composite material, a conductive agent, and a binder, adding a solvent to prepare a slurry, coating the slurry onto the surface of a current collector, and drying to obtain a photocathode. The material and its application system described in this invention exhibit good specific capacity, rate performance, and cycle stability, and demonstrate good energy storage performance under illumination conditions; this invention is beneficial for further reducing electrode polarization and promoting the synergistic enhancement of electron transport and zinc-ion storage.

Description

Technical Field

[0001] This invention relates to a method for preparing zinc-ion batteries, and belongs to the technical field of vanadium selenide-vanadium oxide heterojunction photo-assisted electrochemical energy storage and zinc-ion batteries. Background Technology

[0002] With the rapid development of distributed sensors, environmental monitoring nodes, flexible microelectronic devices, and low-power intelligent devices, energy storage devices not only need to possess high safety and cycle stability, but also need to maintain continuous power supply capabilities in complex environments. For low-power electronic systems deployed in low-light, low-temperature, and unattended scenarios, traditional batteries still have shortcomings in terms of energy supply methods, environmental adaptability, and long-term stable operation. Photo-assisted zinc-ion batteries, because they can combine light energy utilization with electrochemical energy storage processes, show promising application prospects in achieving integrated light energy collection, charge separation, and zinc-ion storage.

[0003] Existing performance improvements in photo-assisted zinc-ion batteries largely rely on a single photoresponse process. However, in practical energy storage, relying on a single process often fails to simultaneously address multiple critical processes such as electron transport, ion diffusion, and interfacial reaction kinetics. This is particularly pronounced under high-rate or complex environmental conditions, where intensified interfacial polarization and restricted ion migration become more significant, leading to substantial capacity decay and reduced rate performance, thus limiting further applications. For example, CN116190833A, an invention entitled "A Photo-Assisted Charging Aqueous Zinc-Ion Battery and Its Preparation Method," discloses a vanadium oxide photocathode, a zinc anode, and a zinc salt aqueous solution as the electrolyte. The photo-assisted charging aqueous zinc-ion battery encapsulates the vanadium oxide photocathode and the zinc anode within a battery casing with openings on the cathode side. A membrane separates the vanadium oxide photocathode and the zinc anode, with electrolyte filling both sides of the membrane. This invention can simultaneously collect and store solar energy in a photo-assisted charging aqueous zinc-ion battery, improving the electrochemical performance of the aqueous zinc-ion battery. Its core design utilizes a vanadium oxide photocathode to achieve photogenerated carrier-assisted charging, which is a single photoresponse process.

[0004] Vanadium selenide materials possess high electronic conductivity and strong light absorption, giving them an advantage in rapid electron transport; vanadium oxide materials exhibit good ion storage activity, demonstrating good electrochemical reactivity during zinc ion insertion / extraction. However, vanadium selenide alone still suffers from deficiencies in structural stability and cycle retention, while vanadium oxide alone generally suffers from low conductivity and slow interfacial charge transport. For example, CN120511406B, an invention entitled "A Large-Area Photoelectric Rechargeable Zinc-Ion Soft-Pack Battery and Its Preparation Method and Application," discloses the following steps: Folding an aluminum-plastic film in half along its center, and processing an optical window in the center of one side of the film; defining an adhesive area around the optical window, and processing a hole array in the adhesive area; bonding an expanded polytetrafluoroethylene (ePTFE) film to the adhesive area of ​​the aluminum-plastic film, and then curing it under ultraviolet light to obtain an aluminum-plastic film with ePTFE film; rolling a photoelectric positive electrode material onto a titanium mesh to obtain a photoelectric rechargeable positive electrode sheet; wrapping a zinc metal negative electrode sheet, a GF / D glass fiber separator, and the photoelectric rechargeable positive electrode sheet into the aluminum-plastic film with ePTFE film from bottom to top, adding electrolyte, and then hot-pressing to seal the edges to obtain a large-area photoelectric rechargeable zinc-ion soft-pack battery. This invention successfully overcomes the technical bottleneck of traditional photoelectric rechargeable zinc-ion soft-pack batteries through optical window design and optimized light-storage synergistic structure. However, it only uses a single V6O 13 The nanosheets result in weak photoelectric gain, and their physical mixing also affects conductivity. The photoresponse is dominated by a single photogenerated carrier process, failing to break through the limitation of a single photoresponse.

[0005] Therefore, there is an urgent need to propose a method for preparing vanadium selenide-vanadium oxide heterojunction photo-assisted zinc-ion batteries to solve the above-mentioned technical problems. Summary of the Invention

[0006] To address the aforementioned problems, a method for preparing a vanadium selenide-vanadium oxide heterojunction photo-assisted zinc-ion battery is provided. A brief overview of the invention is given below to provide a basic understanding of certain aspects of the invention. It should be understood that this overview is not an exhaustive summary of the invention. It is not intended to identify key or essential parts of the invention, nor is it intended to limit the scope of the invention.

[0007] The technical solution of this invention: A method for preparing a vanadium selenide-vanadium oxide heterojunction photo-assisted zinc-ion battery includes the following steps: Step 1: Mix the selenium source solution and the vanadium source solution to obtain the reaction precursor solution; Step 2: Perform a hydrothermal reaction on the precursor solution and wash it to obtain vanadium selenide material; Step 3: Annealing of vanadium selenide material to form a vanadium oxide layer on the surface of vanadium selenide material, resulting in a vanadium selenide / vanadium oxide heterojunction composite material; Step 4: Mix vanadium selenide / vanadium oxide heterojunction composite material, conductive agent and binder, add solvent to make slurry, coat the slurry on the surface of the current collector, and dry to obtain photocathode.

[0008] Preferred method: In step 1, a selenium source is weighed and added to hydrazine hydrate, and stirred to obtain a selenium source solution; a vanadium source and a dispersant are weighed and added to deionized water, and stirred to obtain a vanadium source solution; the selenium source solution and the vanadium source solution are mixed and stirred to obtain a uniform reaction precursor solution.

[0009] Preferably, in step 1, the vanadium source is ammonium metavanadate, the vanadium source is 0.998-1.010 mmol, the selenium source is selenium powder, the selenium source is 0.1577-10.581 g, and the dispersant is polyvinylpyrrolidone, the dispersant is 1 g; Add 5 mL of hydrazine hydrate to the selenium powder and stir for 10-15 min. Add 10 mL of deionized water to the ammonium metavanadate and polyvinylpyrrolidone and stir for 10-15 min. After mixing the two, continue stirring for 80-90 min.

[0010] Preferred step: Step 2, transfer the precursor solution to a reaction vessel for hydrothermal reaction; filter the obtained product and wash it to obtain vanadium selenide material.

[0011] Preferably, in step 2, the hydrothermal reaction temperature is 180°C and the reaction time is 240 min; The reaction products were separated by vacuum filtration and washed sequentially with ethanol and deionized water.

[0012] Preferred step: Step 3, anneal the vanadium selenide material in an air atmosphere, heat it to 300°C at a heating rate of 10°C / min, hold it for 5 minutes, so that a vanadium oxide layer is formed on its surface in situ, thereby constructing a vanadium selenide / vanadium oxide heterojunction composite material.

[0013] Preferred step: Step 4, mix vanadium selenide / vanadium oxide heterojunction composite material, conductive agent and binder in a mass ratio of 7:2:1 to prepare a slurry, coat the slurry onto the current collector and dry it to obtain a photocathode; the current collector is FTO conductive glass, the conductive agent is acetylene black, the binder is polyvinylidene fluoride, and the solvent is N-methylpyrrolidone.

[0014] Preferably, the method further includes step 5, which involves assembling the photocathode, separator, aqueous electrolyte, zinc anode, gasket, and top cover sequentially based on a button cell casing with a light-transmitting window, and then sealing and pressing them together to obtain a photo-assisted zinc-ion battery.

[0015] Preferably, in step 5, the aqueous electrolyte is a 3 mol / L zinc trifluoromethanesulfonate electrolyte, and the negative electrode is a zinc sheet or zinc foil.

[0016] Preferably, the positive electrode active material is a vanadium selenide / vanadium oxide heterojunction composite material, which consists of a vanadium selenide matrix and a vanadium oxide layer formed in situ on its surface. The heterojunction structure can promote the separation and transport of photogenerated carriers and enhance the insertion / extraction reaction of zinc ions.

[0017] The present invention has the following beneficial effects: This invention utilizes controlled surface oxidation of vanadium selenide to construct an in-situ vanadium oxide layer on its surface, thereby forming a tightly bonded vanadium selenide / vanadium oxide heterojunction structure. Compared to single-material systems, this heterostructure can balance the high electronic conductivity of vanadium selenide with the good ion storage activity of vanadium oxide, thus improving the overall energy storage performance of the electrode material.

[0018] This invention uses in-situ surface oxidation to construct heterojunction interfaces. The process is simple and the steps are clear. It does not require additional complex interface assembly processes, which helps to maintain tight interface contact and reduce interface resistance. At the same time, it helps to improve interface charge transport efficiency and improve the charge migration process inside the material and at the interface.

[0019] In this invention, the vanadium selenide substrate provides a conductive framework for rapid electron transport, while the vanadium oxide layer on the surface provides more active sites and improves the zinc ion insertion / extraction process. Therefore, it is beneficial to promote the synergistic process of electron transport and ion diffusion, reduce electrode polarization, and improve rate performance and cycle stability.

[0020] This invention constructs a vanadium selenide / vanadium oxide heterointerface, which facilitates the separation and transport of photogenerated carriers, enhances the material's response to external light, and improves the interfacial reaction process and electrochemical reaction kinetics under light conditions, enabling the device to have better energy storage performance under light-assisted working conditions.

[0021] The heterostructure constructed in this invention not only improves the electron transport performance of the material, but also helps to shorten the migration path of zinc ions in the active material, enhances the electrode reactivity, and thus further improves the adaptability of the electrode material to high-rate working conditions.

[0022] This invention uses FTO conductive glass as the current collector and combines it with a battery structure design with a light-transmitting window, which facilitates the direct action of external light on the photocathode, enabling the light to participate more effectively in the energy storage process. Thus, in addition to having conventional zinc ion storage functions, the device can also achieve light-assisted energy storage under the participation of light.

[0023] This invention, through the construction of heterogeneous interfaces and the design of transparent electrode structures, helps to further improve the synergistic relationship between interface charge separation, electron transport and zinc ion storage, thereby reducing the polarization degree of the device during charging and discharging and improving the overall electrochemical performance.

[0024] The raw materials used in this invention are widely available. The preparation process mainly includes steps such as precursor liquid mixing, hydrothermal reaction, washing and separation, controlled surface oxidation, and electrode assembly. The overall route is simple, the reaction conditions are relatively mild, and it is convenient for laboratory preparation and subsequent scale-up research.

[0025] The materials and battery systems obtained by this invention are not only suitable for conventional zinc-ion energy storage, but also more suitable for expansion into light-assisted zinc-ion batteries, light-assisted energy storage devices and related self-powered microelectronic devices, and have good application prospects. Attached Figure Description

[0026] Figure 1 This is a scanning electron microscope image of the vanadium selenide / vanadium oxide heterojunction composite material in an embodiment of the present invention.

[0027] Figure 2 This is a cyclic voltammetry curve of the vanadium selenide / vanadium oxide heterojunction photocathode in an embodiment of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0029] Specific implementation method one: Combining Figure 1-2 This embodiment describes a method for preparing a vanadium selenide-vanadium oxide heterojunction photo-assisted zinc-ion battery, which includes the following steps: Step 1: Mix the selenium source solution and the vanadium source solution to obtain a homogeneous reaction precursor solution; Step 2: Perform a hydrothermal reaction on the precursor solution and wash it to obtain vanadium selenide material; Step 3: Annealing of vanadium selenide material to form a vanadium oxide layer on the surface of vanadium selenide material, resulting in a vanadium selenide / vanadium oxide heterojunction composite material; Step 4: Mix vanadium selenide / vanadium oxide heterojunction composite material, conductive agent and binder, add solvent to make slurry, coat the slurry on the surface of the current collector, and dry to obtain photocathode; The materials and their application systems involved in the method have good specific capacity, rate performance, and cycle stability, and exhibit good energy storage performance under illumination. At the same time, the construction of heterogeneous interfaces and the design of transparent electrode structures are conducive to further reducing electrode polarization and promoting the synergistic enhancement of electron transport and zinc ion storage. The materials and their battery systems can be applied to the fields of light-assisted zinc ion batteries and related self-powered micro-devices. The raw materials used in this invention are widely available, making it easy to control costs. The preparation process mainly includes steps such as precursor liquid mixing, hydrothermal reaction, washing and separation, controlled surface oxidation, and electrode assembly. The overall route is simple, the reaction conditions are relatively mild, and it is convenient for laboratory preparation and subsequent scale-up research.

[0030] Specific Implementation Method Two: Combining Figure 1-2 This embodiment describes a method for preparing a vanadium selenide-vanadium oxide heterojunction photo-assisted zinc-ion battery. In step 1, 0.1579 g of selenium source is weighed and added to 5 mL of hydrazine hydrate, and stirred for 10 min to obtain a selenium source solution; 1 mmol of vanadium source and 1 g of dispersant are weighed and added to 10 mL of deionized water, and stirred for 10 min to obtain a vanadium source solution; the selenium source solution and the vanadium source solution are mixed and stirred for another 90 min to obtain a homogeneous reaction precursor solution.

[0031] Specific implementation method three: Combining Figure 1-2 This embodiment describes a method for preparing a vanadium selenide-vanadium oxide heterojunction photo-assisted zinc-ion battery. In step 1, the vanadium source is ammonium metavanadate, with a concentration of 0.998-1.010 mmol; the selenium source is selenium powder, with a concentration of 0.1577-10.581 g; and the dispersant is polyvinylpyrrolidone, with a concentration of 1 g. Selenium powder is added to 5 mL of hydrazine hydrate and stirred for 10-15 min to obtain a selenium source solution. Ammonium metavanadate and polyvinylpyrrolidone are added to 10 mL of deionized water and stirred for 10-15 min to obtain a vanadium source solution. The two (selenium source solution and vanadium source solution) are mixed and stirred for 80-90 min to ensure that the precursor solution is evenly dispersed.

[0032] Specific implementation method four: Combination Figure 1-2 This embodiment describes a method for preparing a vanadium selenide-vanadium oxide heterojunction photo-assisted zinc-ion battery. Step 2 involves transferring the homogeneous reaction precursor solution obtained in Step 1 to a reaction vessel and hydrothermally reacting it at 180°C for 240 minutes. After the reaction, the resulting product is filtered and washed with ethanol and deionized water to obtain vanadium selenide material. The vanadium selenide substrate provides a conductive framework for rapid electron transport, while the surface vanadium oxide layer provides numerous active sites and improves the zinc ion insertion / extraction process. Therefore, it facilitates the synergistic effect of electron transport and ion diffusion, reduces electrode polarization, and improves rate performance and cycle stability.

[0033] Specific Implementation Method Five: Combining Figure 1-2 This embodiment describes a method for preparing a vanadium selenide-vanadium oxide heterojunction photo-assisted zinc-ion battery. In step 2, the hydrothermal reaction temperature is 180°C and the reaction time is 240 min. The reaction product was separated by vacuum filtration and washed sequentially with ethanol and deionized water.

[0034] Specific Implementation Method Six: Combination Figure 1-2 This embodiment describes a method for preparing a vanadium selenide / vanadium oxide heterojunction photo-assisted zinc-ion battery. Step 3 involves annealing the vanadium selenide material obtained in step 2 in air, heating it to 300°C at a rate of 10°C / min, and holding it at that temperature for 5 minutes to form a vanadium oxide layer on its surface in situ, thereby constructing a vanadium selenide / vanadium oxide heterojunction composite material. The annealing treatment is a controlled oxidation treatment, where a vanadium oxide layer is formed in situ on the surface of the vanadium selenide material through surface oxidation, while the internal vanadium selenide phase remains, thus constructing a vanadium selenide / vanadium oxide heterojunction structure. The constructed heterostructure not only improves the electron transport performance of the material but also helps to shorten the migration path of zinc ions in the active material, enhancing electrode reactivity and further improving the adaptability of the electrode material to high-rate operating conditions. This invention utilizes controlled surface oxidation of vanadium selenide to construct an in-situ vanadium oxide layer on its surface, thereby forming a tightly bonded vanadium selenide / vanadium oxide heterojunction structure. Compared to single-material systems, this heterostructure can balance the high electronic conductivity of vanadium selenide with the good ion storage activity of vanadium oxide, thus improving the overall energy storage performance of the electrode material. The in-situ surface oxidation method for constructing the heterojunction interface is simple and straightforward, eliminating the need for complex interface assembly processes. This helps maintain tight interface contact and reduce interface resistance, while also improving interface charge transport efficiency and enhancing charge migration processes within the material and at the interface. Furthermore, the vanadium selenide / vanadium oxide heterojunction facilitates the separation and transport of photogenerated carriers, enhances the material's response to external light, and improves the interface reaction process and electrochemical reaction kinetics under illumination conditions, resulting in better energy storage performance of the device under light-assisted operating conditions.

[0035] Specific implementation method seven: Combining Figure 1-2This embodiment describes a method for preparing a vanadium selenide / vanadium oxide heterojunction photo-assisted zinc-ion battery. Step 4 involves mixing the vanadium selenide / vanadium oxide heterojunction composite material obtained in step 3, a conductive agent, and a binder at a mass ratio of 7:2:1. A slurry is prepared using N-methylpyrrolidone as a solvent. The slurry is coated onto a current collector and dried to obtain a photocathode. The current collector is FTO conductive glass, the conductive agent is acetylene black, the binder is polyvinylidene fluoride, and the solvent is N-methylpyrrolidone. The mass ratio of the heterojunction composite material, acetylene black, and polyvinylidene fluoride is 7:2:1. This invention uses FTO conductive glass as the current collector and combines it with a battery structure design featuring a light-transmitting window. This facilitates direct exposure of the photocathode to external light, enabling the light to participate more effectively in the energy storage process. As a result, in addition to the conventional zinc ion storage function, the device can also achieve light-assisted energy storage under illumination. Through the construction of the heterogeneous interface and the design of the light-transmitting electrode structure, the synergistic relationship between interface charge separation, electron transport, and zinc ion storage is further improved, thereby reducing the polarization of the device during charging and discharging and enhancing its overall electrochemical performance.

[0036] Specific implementation method eight: Combination Figure 1-2 This embodiment describes a method for preparing a vanadium selenide-vanadium oxide heterojunction photo-assisted zinc-ion battery, which further includes step 5: based on a button cell casing with a light-transmitting window, the photocathode, separator, 3 mol / L zinc trifluoromethanesulfonate aqueous electrolyte, zinc anode, gasket, and top cover are assembled sequentially, and then sealed and pressed to obtain the photo-assisted zinc-ion battery.

[0037] Specific Implementation Method Nine: Combining Figure 1-2 This embodiment describes a method for preparing a vanadium selenide / vanadium oxide heterojunction photo-assisted zinc-ion battery. In step 5, the aqueous electrolyte is a 3 mol / L zinc trifluoromethanesulfonate electrolyte, and the negative electrode is a zinc sheet or zinc foil. This invention constructs a heterostructure material with high conductivity, good light response, and excellent zinc-ion storage capacity, becoming an important research direction for improving the performance of photo-assisted zinc-ion batteries. By controlling the surface oxidation of vanadium selenide, a vanadium oxide layer can be constructed in situ on its surface, forming a tightly bonded vanadium selenide / vanadium oxide heterojunction structure. This heterojunction interface is beneficial for promoting the separation and transport of photogenerated carriers, and while maintaining the advantages of the vanadium selenide conductive framework, the introduction of a vanadium oxide active layer improves the zinc-ion storage behavior, thereby achieving a synergistic enhancement of electron conduction and ion diffusion.

[0038] Specific Implementation Method Ten: Combining Figure 1-2This embodiment describes a method for preparing a vanadium selenide / vanadium oxide heterojunction photo-assisted zinc-ion battery. The positive electrode active material of this battery is a vanadium selenide / vanadium oxide heterojunction composite material. The composite material consists of a vanadium selenide matrix and a vanadium oxide layer formed in situ on its surface. The heterojunction structure promotes the separation and transport of photogenerated carriers and enhances the insertion / extraction reaction of zinc ions. This invention overcomes the limitations of existing technologies that only address these limitations through material morphology and encapsulation processes, achieving improvements in capacity and rate performance. The materials and battery systems obtained by this invention are not only suitable for conventional zinc-ion energy storage, but also more suitable for expansion into light-assisted zinc-ion batteries, light-assisted energy storage devices and related self-powered microelectronic devices, and have good application prospects.

[0039] Example 1 A method for preparing a vanadium selenide / vanadium oxide heterojunction photo-assisted zinc-ion battery includes the following steps: Step 1: Weigh 0.1579 g of selenium powder and add it to 5 mL of hydrazine hydrate. Stir for 10 min under magnetic stirring to obtain a homogeneous selenium source solution. Separately weigh 1 mmol of ammonium metavanadate and 1 g of polyvinylpyrrolidone and add them to 10 mL of deionized water. Stir for 10 min to obtain a vanadium source solution. Then mix the selenium source solution and the vanadium source solution and continue stirring for 90 min to obtain a homogeneous reaction precursor solution.

[0040] Step 2: Transfer the homogeneous reaction precursor solution obtained in Step 1 to a polytetrafluoroethylene-lined high-pressure reactor and carry out a hydrothermal reaction at 180°C for 240 min. After the reaction is completed, allow it to cool naturally to room temperature, remove the product, collect it by vacuum filtration, and wash it with ethanol and deionized water to remove unreacted residues and impurities, thus obtaining vanadium selenide material.

[0041] Step 3: The vanadium selenide material obtained in Step 2 is placed in an air atmosphere for annealing treatment. The temperature is increased to 300 ℃ at a heating rate of 10 ℃ / min and held for 5 min to allow controlled oxidation of its surface. While retaining the internal vanadium selenide phase, a vanadium oxide layer is formed in situ on the surface, thereby constructing a vanadium selenide / vanadium oxide heterojunction composite material.

[0042] Step 4: Take the above vanadium selenide / vanadium oxide heterojunction composite material, acetylene black and polyvinylidene fluoride, mix them in a mass ratio of 7:2:1, and add N-methylpyrrolidone to make a uniform slurry; coat the obtained slurry on the surface of FTO conductive glass and dry it to obtain a photocathode.

[0043] Step 5: Based on the button cell casing with a light-transmitting window, assemble the photocathode, separator, 3 mol / L zinc trifluoromethanesulfonate aqueous electrolyte, zinc sheet negative electrode, gasket and top cover in order from bottom to top, and then seal and press to obtain a photo-assisted zinc ion battery.

[0044] The obtained samples were characterized and their performance tested. Scanning electron microscope images of the obtained vanadium selenide / vanadium oxide heterojunction composite material are shown below. Figure 1 As shown, this indicates that the prepared material has a relatively uniform microstructure. The cyclic voltammetry curve of the prepared photocathode is shown in the figure. Figure 2 As shown, this indicates that the electrode has good electrochemical reactivity. The constant current charge-discharge curve of the assembled photo-assisted zinc-ion battery is shown in the figure. Figure 1-2 As shown, this indicates that the device has a stable charge and discharge capability.

[0045] Example 2 A method for preparing a vanadium selenide / vanadium oxide heterojunction photo-assisted zinc-ion battery includes the following steps: Step 1: Weigh 0.1579 g of selenium powder and add it to 5 mL of hydrazine hydrate, and stir for 10 min; separately, add 1 mmol of ammonium metavanadate and 1 g of polyvinylpyrrolidone to 10 mL of deionized water, and stir for 10 min; mix the two solutions and continue stirring for 90 min to obtain a homogeneous precursor solution.

[0046] Step 2: Transfer the precursor solution to a polytetrafluoroethylene-lined high-pressure reactor and perform a hydrothermal reaction at 180 °C for 240 min. After the reaction is completed, remove the product, filter it, and wash it with ethanol and deionized water to obtain vanadium selenide material.

[0047] Step 3: The obtained vanadium selenide material is heated to 300 ℃ in air at a heating rate of 10 ℃ / min and held for 5 min to obtain vanadium selenide / vanadium oxide heterojunction composite material.

[0048] Step 4: Mix the obtained heterojunction composite material, acetylene black and polyvinylidene fluoride in a mass ratio of 7:2:1, add N-methylpyrrolidone to make a slurry, coat it on the surface of FTO conductive glass, and dry it to obtain a photocathode.

[0049] Step 5: Assemble a light-assisted zinc-ion battery using a button cell casing with a light-transmitting window. The electrolyte is a 3 mol / L zinc trifluoromethanesulfonate aqueous electrolyte, and the negative electrode is a zinc sheet.

[0050] Without departing from the technical solution of this invention, the number of washing cycles in step 2, the slurry viscosity adjustment method in step 4, and the battery packaging structure in step 5 can all be appropriately adjusted according to actual needs, but all of them fall within the protection scope of this invention.

[0051] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutation and combination. Therefore, the present invention will not describe the technical solutions after permutation and combination one by one, but it should be understood that the technical solutions after permutation and combination have been disclosed by the present invention.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a vanadium selenide-vanadium oxide heterojunction photo-assisted zinc-ion battery, characterized in that: Includes the following steps: Step 1: Mix the selenium source solution and the vanadium source solution to obtain the reaction precursor solution; Step 2: Perform a hydrothermal reaction on the precursor solution and wash it to obtain vanadium selenide material; Step 3: Annealing of vanadium selenide material to form a vanadium oxide layer on the surface of vanadium selenide material, resulting in a vanadium selenide / vanadium oxide heterojunction composite material; Step 4: Mix vanadium selenide / vanadium oxide heterojunction composite material, conductive agent and binder, add solvent to make slurry, coat the slurry on the surface of the current collector, and dry to obtain photocathode.

2. The method for preparing a vanadium selenide-vanadium oxide heterojunction photo-assisted zinc-ion battery according to claim 1, characterized in that: In step 1, a selenium source is weighed and added to hydrazine hydrate, and stirred to obtain a selenium source solution; a vanadium source and a dispersant are weighed and added to deionized water, and stirred to obtain a vanadium source solution; the selenium source solution and the vanadium source solution are mixed and stirred to obtain a uniform reaction precursor solution.

3. The method for preparing a vanadium selenide-vanadium oxide heterojunction photo-assisted zinc-ion battery according to claim 2, characterized in that: In step 1, the vanadium source is ammonium metavanadate, and the vanadium source is 0.998-1.010 mmol; the selenium source is selenium powder, and the selenium source is 0.1577-10.581 g; and the dispersant is polyvinylpyrrolidone, and the dispersant is 1 g. Add 5 mL of hydrazine hydrate to the selenium powder and stir for 10-15 min. Add 10 mL of deionized water to the ammonium metavanadate and polyvinylpyrrolidone and stir for 10-15 min. After mixing the two, continue stirring for 80-90 min.

4. The method for preparing a vanadium selenide-vanadium oxide heterojunction photo-assisted zinc-ion battery according to claim 3, characterized in that: Step 2: Transfer the precursor solution to a reaction vessel for hydrothermal reaction; filter the resulting product and wash it to obtain vanadium selenide material.

5. The method for preparing a vanadium selenide-vanadium oxide heterojunction photo-assisted zinc-ion battery according to claim 4, characterized in that: In step 2, the hydrothermal reaction temperature is 180℃ and the reaction time is 240 min; The reaction products were separated by vacuum filtration and washed sequentially with ethanol and deionized water.

6. The method for preparing a vanadium selenide-vanadium oxide heterojunction photo-assisted zinc-ion battery according to claim 5, characterized in that: Step 3: Anneal the vanadium selenide material in an air atmosphere, heating it to 300°C at a heating rate of 10°C / min and holding it at that temperature for 5 minutes to form a vanadium oxide layer on its surface in situ, thereby constructing a vanadium selenide / vanadium oxide heterojunction composite material.

7. The method for preparing a vanadium selenide-vanadium oxide heterojunction photo-assisted zinc-ion battery according to claim 6, characterized in that: Step 4: Mix the vanadium selenide / vanadium oxide heterojunction composite material, conductive agent, and binder in a mass ratio of 7:2:1 to prepare a slurry. Coat the slurry onto the current collector and dry it to obtain a photocathode. The current collector is FTO conductive glass, the conductive agent is acetylene black, the binder is polyvinylidene fluoride, and the solvent is N-methylpyrrolidone.

8. The method for preparing a vanadium selenide-vanadium oxide heterojunction photo-assisted zinc-ion battery according to claim 7, characterized in that: The process also includes step 5, which involves assembling the photocathode, separator, aqueous electrolyte, zinc anode, gasket, and top cover sequentially based on a button cell casing with a light-transmitting window, and then sealing and pressing them together to obtain a photo-assisted zinc-ion battery.

9. The method for preparing a vanadium selenide-vanadium oxide heterojunction photo-assisted zinc-ion battery according to claim 8, characterized in that: In step 5, the aqueous electrolyte is a 3 mol / L zinc trifluoromethanesulfonate electrolyte, and the negative electrode is a zinc sheet or zinc foil.

10. The battery prepared by the method for preparing a vanadium selenide-vanadium oxide heterojunction photo-assisted zinc-ion battery according to claims 1-9, characterized in that: Its positive electrode active material is a vanadium selenide / vanadium oxide heterojunction composite material. The composite material consists of a vanadium selenide matrix and a vanadium oxide layer formed in situ on its surface. The heterojunction structure can promote the separation and transport of photogenerated carriers and enhance the insertion / extraction reaction of zinc ions.

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