A phosphate ester organic matter intercalated vanadium pentoxide positive electrode composite material, a preparation method and application thereof

Abstract

The application discloses an organic matter intercalated vanadium pentoxide (V2O5) positive electrode composite material and a preparation method and application thereof, and belongs to the technical field of micro-nano materials and electrochemistry. The application uses V2O5 with a wide source as a raw material, and uses bis(4-nitrophenyl) phosphate, diphenyl phosphate, ethyl phosphate and triethyl phosphate as objects to be inserted into adjacent layers of the V2O5 to serve as a support. The application not only improves the interlayer spacing of the V2O5, overcomes the problem that zinc ions are difficult to be deintercalated in the interlayer of the V2O5 in a cycle process, but also improves the structural stability, and improves the capacity and cycle stability.

Description

Technical Field

[0001] This invention belongs to the field of aqueous zinc-ion battery technology, specifically relating to a phosphate ester-based organic intercalated vanadium pentoxide cathode composite material, its preparation method, and its application. Background Technology

[0002] Currently, lithium batteries are the most commonly used batteries in secondary energy storage devices due to their high energy density and long cycle life. However, the limited lithium resources leading to continuously increasing costs, the limitations of battery-grade lithium carbonate purification technology, and the safety issues posed by the flammability and explosiveness of electrolytes are all factors restricting the development of lithium-ion batteries. Aqueous rechargeable batteries are considered a promising alternative, especially for large-scale energy storage stations. Among them, aqueous zinc-ion batteries are particularly noteworthy due to their safety, economy, and environmental friendliness, as well as the high theoretical capacity of the zinc metal anode (5585 mAh cm⁻¹). -3 Its characteristics, such as low redox potential (-0.762 V) and electrochemical stability in sulfate solutions and near-neutral or slightly acidic aqueous electrolytes, have made it a research hotspot.

[0003] The gravimetric energy density, power density, and cost of aqueous zinc-ion batteries largely depend on the cathode material. The stability and performance of the cathode structure are crucial to the cycle stability and electrochemical performance of the entire battery system.

[0004] Currently, suitable materials for aqueous zinc-ion cathodes include Prussian blue analogues, manganese-based oxides, vanadium-based oxides, and organic compounds. Among these, V₂O₅, a typical vanadium-based material, has been extensively studied due to its tunable layered structure and the multiple redox states of vanadium. However, due to the synergistic effect of zinc ions and water molecules, zinc ions typically exist as hydrated zinc ions, with a diameter larger than the interlayer spacing of V₂O₅. This makes it difficult for zinc ions to intercalate and deintercalate within the V₂O₅ layers, thus affecting the electrochemical reaction. Furthermore, the interlayer bonding force of V₂O₅ is van der Waals force, leading to gradual layer-to-layer peeling during the reaction, resulting in structural collapse and loss of electrochemical activity. To promote reaction kinetics and increase the structural stability of V₂O₅, a straightforward approach is to introduce metal ions, water molecules, and organic molecules to expand the interlayer spacing, thereby improving the zinc ion intercalation / deintercalation rate and cycle performance. Additionally, metal ions, water molecules, and organic molecules can act as interlayer supports, further enhancing the structural stability of V₂O₅.

[0005] However, although the application of V2O5 in aqueous zinc ions has been gradually developed, the preparation method of aqueous zinc ion cathode materials prepared by V2O5 in the existing technology is complicated, and the specific capacity and cycle stability of the prepared cathode materials are generally poor. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing organic intercalated V2O5 cathode composite material and its application. The preparation method utilizes organic molecules as interlayer pillars of V2O5 to increase the interlayer spacing and improve the interlayer bonding force. The raw materials for this preparation method are widely available, the preparation process is simple, and the prepared material has a high actual specific capacity when used as a cathode material in aqueous zinc-ion batteries.

[0007] The technical solution adopted in this invention is:

[0008] An organic-intercalated vanadium pentoxide cathode composite material, wherein the composite material is a sheet material, the organic material is a phosphate ester organic material, and the phosphate ester organic material is intercalated between adjacent layers of V2O5.

[0009] Furthermore, the interlayer spacing between two adjacent V2O5 layers is 1.1~1.3 nm.

[0010] Furthermore, the phosphate ester organic compound is any one of bis(4-nitrobenzene) phosphate, diphenyl phosphate, ethyl phosphate, and triethyl phosphate.

[0011] A method for preparing an organic-intercalated vanadium pentoxide cathode composite material includes the following steps:

[0012] (1) Preparation of V2O5 precursor solution: Dissolve V2O5 in hydrogen peroxide solution and stir evenly to obtain V2O5 precursor solution;

[0013] (2) Preparation of organic precursor solution: Dissolve bis(4-nitrobenzene) phosphate, diphenyl phosphate, ethyl phosphate and triethyl phosphate in N-methylpyrrolidone, stir until completely dissolved, and then add deionized water to obtain organic precursor solution;

[0014] (3) Take the V2O5 precursor solution obtained in step (1) and the organic precursor solution obtained in step (2), mix them, stir evenly, and then carry out a hydrothermal reaction.

[0015] (4) The hydrothermal products are centrifuged, washed and dried to obtain the organic intercalated vanadium pentoxide cathode composite material.

[0016] Furthermore, in step (1), the mass fraction of hydrogen peroxide is 5~10%, and the concentration of V2O5 is 0.1~0.3 M.

[0017] Furthermore, in step (3), the molar ratio of V2O5 to organic matter is 0.2~8, and the concentration of organic matter precursor is 0.02~0.2M.

[0018] Furthermore, in step (3), the ratio of N-methylpyrrolidone to deionized water in the organic precursor solution is 0.3~3.

[0019] Furthermore, in step (3), the hydrothermal reaction temperature is 120~220 ℃ and the hydrothermal reaction time is 10~20 h.

[0020] Further, in step (4), the centrifugation speed is 6000~10000 r / min, the centrifugation time is 3~10 min; the washing is carried out with water and anhydrous ethanol in sequence; the drying conditions are vacuum drying, the drying temperature is 50~100 ℃, and the drying time is 10~15 h.

[0021] The above-mentioned organic intercalated vanadium pentoxide cathode composite material is used as a cathode material for aqueous zinc-ion batteries.

[0022] The beneficial effects of this invention are:

[0023] 1. The preparation method of the present invention utilizes the characteristics of the layered structure of V2O5 to intercalate organic molecules between V2O5 layers, effectively improving the problems of poor specific capacity and cycling performance caused by the difficulty of zinc ion insertion / extraction and poor structural stability during V2O5 recycling. It increases the interlayer spacing of V2O5, facilitates the insertion / extraction of zinc ions, exposes more active sites of V2O5, improves capacity, increases interlayer binding force, and improves the structural stability of V2O5.

[0024] 2. The battery cathode material prepared by the preparation method of the present invention exhibits superior electrochemical performance. The specific capacity of the material can reach 421 mAh / g at a current density of 0.2 A / g. After 100 cycles, the capacity remains at 417 mAh / g, with a capacity retention rate of 99%. At a current density of 5 A / g, the specific capacity still remains at 199 mAh / g after 1000 cycles, with a capacity decay of only 0.097% per cycle.

[0025] 3. The preparation method of the present invention uses vanadium pentoxide as raw material, which is widely available. It is synthesized by a one-step hydrothermal method, which is simple, efficient, and has a short hydrothermal reaction time, thus effectively saving energy. Attached Figure Description

[0026] Figure 1 This is a schematic diagram illustrating the synthesis principle of the bis(4-nitrobenzene) phosphate intercalated V2O5 cathode composite material in Embodiment 1 of the present invention;

[0027] Figure 2 The XRD pattern of the bis(4-nitrobenzene) phosphate intercalated V2O5 cathode composite material of Embodiment 1 of the present invention;

[0028] Figure 3 The infrared spectrum of the bis(4-nitrobenzene) phosphate intercalated V2O5 cathode composite material of Example 1 of the present invention;

[0029] Figure 4 XPS image of the bis(4-nitrobenzene) phosphate intercalated V2O5 cathode composite material of Example 1 of the present invention;

[0030] Figure 5 This is a scanning electron microscope image of the bis(4-nitrobenzene) phosphate intercalated V2O5 cathode composite material of Example 1 of the present invention;

[0031] Figure 6 This is a transmission electron microscope (TEM) image of the bis(4-nitrobenzene) phosphate intercalated V2O5 cathode composite material of Example 1 of the present invention;

[0032] Figure 7 This is a high-resolution transmission electron microscope image of the bis(4-nitrobenzene) phosphate intercalated V2O5 cathode composite material of Example 1 of the present invention;

[0033] Figure 8 The cycling curve of the bis(4-nitrobenzene) phosphate intercalated V2O5 cathode composite material of Example 1 of the present invention when used as a cathode material for an aqueous zinc-ion battery at a current density of 0.1 A / g.

[0034] Figure 9 The rate performance diagrams for the bis(4-nitrobenzene) phosphate intercalated V2O5 cathode composite material of Example 1 of the present invention, when used as a cathode material for an aqueous zinc-ion battery, are shown at current densities of 0.1, 0.3, 0.5, 1, 3, and 5 A / g.

[0035] Figure 10 The diagram shows the long-cycle performance of the bis(4-nitrobenzene) phosphate intercalated V2O5 cathode composite material of Example 1 of the present invention when used as a cathode material for an aqueous zinc-ion battery, after 1000 cycles at 5 A / g.

[0036] Figure 11 The cycling curve of the diphenyl phosphate intercalated V2O5 cathode composite material of Example 2 of the present invention when used as the cathode material of an aqueous zinc-ion battery at a current density of 0.1 A / g.

[0037] Figure 12 The cycling curve of the ethyl phosphate intercalated V2O5 cathode composite material of Example 3 of the present invention when used as the cathode material of an aqueous zinc-ion battery at a current density of 0.1 A / g.

[0038] Figure 13 The image shows the XRD pattern of the ethyl phosphate intercalated V2O5 cathode composite material of Example 3 of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0040] Example 1

[0041] In this embodiment, the organic-intercalated vanadium pentoxide cathode composite material is a bis(4-nitrobenzene) phosphate-intercalated V₂O₅ cathode composite material (BVO for short), and its preparation method is as follows:

[0042] (1) Preparation of V2O5 precursor solution: Add deionized water to 35% hydrogen peroxide solution and mix and dilute to 5% by mass, with a total solution of 20 mL. Dissolve 0.4 g of V2O5 in the diluted hydrogen peroxide solution and stir for 15 min.

[0043] (2) Preparation of organic precursor solution: Dissolve 0.34 g of bis(4-nitrobenzene) phosphate in 10 ml of N-methylpyrrolidone (NMP), sonicate until completely dissolved, and then add 10 ml of deionized water.

[0044] (3) Mix the two precursor solutions from steps (1) and (2), stir for 10 min and then carry out a hydrothermal reaction at a temperature of 120 °C for 10 h.

[0045] (4) The product obtained after hydrothermal treatment is collected after centrifugation, washing and drying. The centrifugation speed is 6000 r / min and the centrifugation time is 10 min. Water and ethanol are used alternately for washing, 3 times each. After centrifugation, the product is placed in a vacuum drying oven and dried at 50 ℃ for 15 h. The dried sample is collected, ground and passed through a 300-mesh sieve to obtain the BVO.

[0046] BVO-Zn aqueous batteries were prepared using the BVO prepared in this embodiment:

[0047] A positive electrode was prepared by mixing bis(4-nitrobenzene) phosphate intercalated V2O5 positive electrode composite material, carbon black (Super-P), and polyvinylidene fluoride (PVDF) at a mass ratio of 7:2:1. The thoroughly mixed slurry was uniformly coated onto a stainless steel mesh and then vacuum dried at 80°C for 12 h. A CR2025 coin cell was assembled using zinc foil as the negative electrode, 1.8 M zinc trifluoromethanesulfonate aqueous solution as the electrolyte, and GF / D glass fiber as the separator.

[0048] This embodiment describes the preparation of a bis(4-nitrobenzene) phosphate intercalated V₂O₅ cathode composite material using a one-step hydrothermal method. The preparation method is simple, and during the hydrothermal process, the bis(4-nitrobenzene) phosphate is intercalated between the V₂O₅ layers. Figure 1As shown, increasing the interlayer spacing of V2O5 from 0.44 nm to 1.24 nm can broaden the ion transport channels, facilitating zinc ion insertion / extraction; expose more active sites, increasing specific capacity; and utilize organic molecules as interlayer supports for V2O5, improving interlayer bonding force, so that V2O5 maintains structural integrity and stability during repeated zinc ion insertion / extraction processes.

[0049] Figure 2 XRD and Figure 3 The infrared spectrum confirms the successful intercalation of bis(4-nitrobenzene) phosphate. The presence of the nitro functional group characteristic of bis(4-nitrobenzene) phosphate in the infrared spectrum indicates that the material contains bis(4-nitrobenzene) phosphate.

[0050] Figure 4 XPS analysis further confirms the successful intercalation of bis(4-nitrobenzene) phosphate, with some V changing from +5 to +4 valence. The synthesized bis(4-nitrobenzene) phosphate intercalated V₂O₅ cathode composite material is a layered material. Figure 5 The scanning electron microscope images show that the composite material is in the form of thin sheets, which exposes the active sites inside the nanosheets compared to the initial tightly packed V2O5 nanosheets.

[0051] exist Figure 6 The transmission electron microscope image also shows that the bis(4-nitrobenzene) phosphate intercalated V2O5 cathode composite material is a thin nanosheet.

[0052] exist Figure 7 The high-resolution transmission electron microscopy image shows that the interlayer spacing of the bis(4-nitrobenzene) phosphate intercalated V2O5 cathode composite material is 1.24 nm, and the increased interlayer spacing is beneficial to the electrochemical reaction.

[0053] The electrochemical performance of the bis(4-nitrobenzene) phosphate intercalated V2O5 cathode composite material was tested in an aqueous zinc-ion battery. Figure 8 As shown, at a current density of 0.2 A / g, the specific capacity can reach 421 mAh / g, and after 100 cycles, the capacity remains at 417, with a capacity retention of 99%.

[0054] exist Figure 9 In the rate performance test, the electrode exhibited excellent rate performance, with a capacity of 225 mAh / g at a current density of 5 A / g. Furthermore, after cycling at a high current and then cycling at a low current, the capacity was still maintained, indicating that the electrode has good reversibility.

[0055] Figure 10At a current density of 5 A / g, the specific capacity of the electrode remained at 199 mAh / g after 1000 cycles, with a capacity decay of only 0.097% per cycle, indicating that the electrode has good structural stability.

[0056] Example 2

[0057] In this embodiment, the organic-intercalated vanadium pentoxide cathode composite material is a diphenyl phosphate-intercalated V₂O₅ cathode composite material (DVO for short), and the method steps are as follows:

[0058] (1) Preparation of V2O5 precursor solution: Add deionized water to 35% hydrogen peroxide solution to dilute to 8%, and make a total of 20 mL of solution. Dissolve 0.68 g of V2O5 in the above diluted hydrogen peroxide solution and stir for 15 min.

[0059] (2) Preparation of organic precursor solution: Dissolve 0.12 g of diphenyl phosphate in 15 ml of N-methylpyrrolidone (NMP), sonicate until completely dissolved, and then add 5 ml of deionized water.

[0060] (3) Mix the two precursor solutions obtained in steps (1) and (2), stir for 10 min and then carry out hydrothermal reaction at a hydrothermal temperature of 180 °C for 15 h.

[0061] (4) The product obtained after hydrothermal treatment is collected after centrifugation, washing and drying. The centrifugation speed is 8000 r / min and the centrifugation time is 6 min. Water and ethanol are used alternately during washing, 3 times each. After centrifugation, the product is placed in a vacuum drying oven and dried at 70 ℃ for 12 h. The dried sample is collected, ground and passed through a 300-mesh sieve to obtain the DVO.

[0062] DVO-Zn aqueous batteries were prepared using the DVO prepared in this embodiment:

[0063] A positive electrode was prepared by mixing diphenyl phosphate intercalated V₂O₅ composite material, carbon black (Super-P), and polyvinylidene fluoride (PVDF) in a mass ratio of 7:2:1. The thoroughly mixed slurry was uniformly coated onto a stainless steel mesh and then vacuum dried at 80 °C for 12 h. A CR2025 coin cell was assembled using zinc foil as the negative electrode, 1.8 M zinc trifluoromethanesulfonate aqueous solution as the electrolyte, and GF / D glass fiber as the separator.

[0064] The electrochemical performance of the diphenyl phosphate intercalated V₂O₅ cathode composite material was tested in an aqueous zinc-ion battery. Figure 11As shown, at a current density of 0.2 A / g, the specific capacity can reach 332 mAh / g, and after 100 cycles, the capacity remains at 357, indicating an increase in capacity. This demonstrates the good electrochemical performance and stable structure of the diphenyl phosphate intercalated V2O5 cathode composite material.

[0065] Example 3

[0066] In this embodiment, the organic-intercalated vanadium pentoxide cathode composite material is an ethyl phosphate-intercalated V₂O₅ cathode composite material (referred to as EVO), and the method steps are as follows:

[0067] (1) Preparation of V2O5 precursor solution: Add deionized water to 35% hydrogen peroxide solution to dilute to 10%, and make a total of 20 mL of solution. Dissolve 1 g of V2O5 in the above diluted hydrogen peroxide solution and stir for 15 min.

[0068] (2) Preparation of organic precursor solution: Dissolve 0.1 g of ethyl phosphate in 5 ml of N-methylpyrrolidone (NMP), sonicate until completely dissolved, and then add 15 ml of deionized water.

[0069] (3) Mix the two precursor solutions obtained in steps (1) and (2), stir for 10 min and then carry out hydrothermal reaction at a hydrothermal temperature of 220 °C for 10 h.

[0070] (4) The product obtained after hydrothermal treatment was collected after centrifugation, washing, and drying. The centrifugation speed was 6000 r / min and the centrifugation time was 10 min. Water and ethanol were used alternately for washing, 3 times each. After centrifugation, the product was placed in a vacuum drying oven and dried at 90 ℃ for 10 h. The dried sample was collected, ground, and passed through a 300-mesh sieve.

[0071] like Figure 13 , is the XRD pattern of the material prepared in Example 3. In the figure, the 2θ of the (001) crystal plane is 7.7. According to Bragg's formula, the spacing of the (001) crystal plane is 1.13 nm, that is, the spacing between the crystal planes is 1.13 nm.

[0072] EVO-Zn aqueous batteries were prepared using the EVO prepared in this embodiment.

[0073] A positive electrode was prepared by mixing ethyl phosphate intercalated V₂O₅ composite material, carbon black (Super-P), and polyvinylidene fluoride (PVDF) in a mass ratio of 7:2:1. The thoroughly mixed slurry was uniformly coated onto a stainless steel mesh and then vacuum dried at 80 °C for 12 h. A CR2025 coin cell was assembled using zinc foil as the negative electrode, 1.8 M zinc trifluoromethanesulfonate aqueous solution as the electrolyte, and GF / D glass fiber as the separator.

[0074] The electrochemical performance of the ethyl phosphate intercalated V₂O₅ cathode composite material was tested in an aqueous zinc-ion battery. Figure 12 As shown, at a current density of 0.2 A / g, the specific capacity can reach 313 mAh / g, and after 100 cycles, the capacity remains at 352 mAh / g, showing an increase in capacity. This indicates that the ethyl phosphate intercalated V2O5 cathode composite material has good electrochemical performance and a stable structure.

[0075] It should be noted that the above embodiments are only used to illustrate the present invention, but the present invention is not limited to the above embodiments. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. An organic-intercalated vanadium pentoxide cathode composite material, characterized in that, The composite material is a layered material, and the organic matter is a phosphate ester organic matter. The phosphate ester organic matter is intercalated between adjacent layers of V2O5, and the interlayer spacing between two adjacent V2O5 layers is 1.1~1.3 nm. The phosphate ester organic matter is any one of bis(4-nitrobenzene) phosphate, diphenyl phosphate, ethyl phosphate, and triethyl phosphate. The preparation method of the above-mentioned organic-intercalated vanadium pentoxide cathode composite material includes the following steps: (1) Preparation of V2O5 precursor solution: Dissolve V2O5 in hydrogen peroxide solution and stir evenly to obtain V2O5 precursor solution; (2) Preparation of organic precursor solution: Dissolve phosphate ester organic compounds in N-methylpyrrolidone, stir until completely dissolved, and then add deionized water to obtain organic precursor solution; (3) Take the V2O5 precursor solution obtained in step (1) and the organic precursor solution obtained in step (2), mix them, stir evenly and then carry out hydrothermal reaction. The molar ratio of V2O5 to organic matter is 0.2~8, and the concentration of organic precursor is 0.02~0.2M. (4) The hydrothermal products are centrifuged, washed and dried to obtain the organic-intercalated vanadium pentoxide cathode composite material; In step (1), the mass fraction of hydrogen peroxide is 5~10%, and the concentration of V2O5 is 0.1~0.3 M.

2. The organic-intercalated vanadium pentoxide cathode composite material as described in claim 1, characterized in that, In step (3), the ratio of N-methylpyrrolidone to deionized water in the organic precursor solution is 0.3 to 3.

3. The organic-intercalated vanadium pentoxide cathode composite material as described in claim 1, characterized in that, In step (3), the hydrothermal reaction temperature is 120~220 ℃ and the hydrothermal reaction time is 10~20 h.

4. The organic-intercalated vanadium pentoxide cathode composite material as described in claim 1, characterized in that, In step (4), the centrifugation speed is 6000~10000 r / min and the centrifugation time is 3~10 min; the washing is done with water and anhydrous ethanol in sequence; the drying conditions are vacuum drying, the drying temperature is 50~100 ℃ and the drying time is 10~15 h.

5. The application of the organic intercalated vanadium pentoxide cathode composite material as described in any one of claims 1-4 as a cathode material for aqueous zinc-ion batteries.

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