A V2CT x -V2O x Materials, their preparation methods and applications

Abstract

This invention belongs to the field of aqueous zinc-ion battery technology, specifically relating to a V2CT. x -V2O x Materials, preparation methods, and applications. The V2CT provided by this invention... x -V2O x Materials, including multi-slice V2CT x Nanosheets and grown in the multilayer V2CT x V2O on the surface of the layered structure of nanosheets x The V2CT provided by this invention x -V2O x Materials in multi-layer V2CT x V2O grown on the surface of nanosheet sheet structure x V2O based on a large interlayer spacing x With multi-slice V2CT x The synergistic effect of nanosheets results in excellent electrochemical performance. Furthermore, this invention utilizes a simple hydrothermal method to synthesize multilayer V2CT. x After alkalization and subsequent oxidation, the nanosheets can be directly applied to V2CT. x V2O grows on the surface of nanosheets x The preparation method provided by this invention is simple, highly reproducible, and features high safety, good stability, no pollution, and environmental friendliness, making it suitable for commercial application.

Description

Technical Field

[0001] This invention belongs to the field of aqueous zinc-ion battery technology, specifically relating to a V2CT. x -V2O x Materials, their preparation methods, and applications. Background Technology

[0002] With the continuous development of science and technology, human demand for green energy and efficient energy storage devices is constantly increasing. Currently, lithium-ion batteries have become one of the main energy storage devices due to their high energy density and good cycle stability. However, due to the scarcity of lithium resources, potential safety issues, and environmental pollution problems, they cannot meet the ever-increasing energy demand. As a favorable alternative to lithium-ion batteries, aqueous zinc-ion batteries have the characteristics of low cost, high safety, and environmental friendliness, and have broad application prospects in the future new energy field.

[0003] Since the introduction of aqueous zinc-ion batteries, numerous researchers have dedicated themselves to developing high-performance cathode materials. However, issues such as cathode material dissolution and adverse effects from electrostatic interactions lead to capacity decay in aqueous zinc-ion batteries, hindering their development. To address the cathode material dissolution problem, Jaekook Kim et al. proposed using a carbon coating in Journal of Energy Chemistry, 2017, (26), 815-819 to suppress cathode dissolution and stabilize the material's structure. Results showed that at the same current density, the electrochemical performance of the coated and uncoated electrodes improved, with the capacity increasing from 213 mAh / g to 272 mAh / g, indicating that the improvement was not significant. Furthermore, Jianfeng Sheng et al., in J. Mater. Chem. A, 2021, (9), 17994, proposed using Zn... 2+ Intercalation was used to mitigate electrostatic interactions, and the results showed that 96.4% of the capacity was retained at a current density of 10 A / g. However, cation intercalation leads to the formation of metal vanadates with the cathode material during cycling, resulting in increased interfacial resistance and consequently, a decrease in battery life. Summary of the Invention

[0004] The purpose of this invention is to provide a V2CT. x -V2O x Materials, preparation methods, and applications; V2CT provided by this invention x -V2O x The material exhibits excellent electrochemical properties, as demonstrated by the V2CT provided by this invention. x -V2O xThe resulting positive electrode material exhibits excellent cycle performance, high energy density, high power density, and large specific capacity.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a V2CT x -V2O x Materials, including multi-slice V2CT x Nanosheets and grown in the multilayer V2CT x V2O on the surface of the layered structure of nanosheets x .

[0007] This invention provides the V2CT described in the above technical solution. x -V2O x The method for preparing the material includes the following steps:

[0008] Multi-layer V2CT x Nanosheets were mixed with an inorganic strong alkali solution and subjected to alkali-based layer expansion treatment to obtain alkali-treated V2CT. x Nanosheets;

[0009] The alkalized V2CT x A hydrothermal reaction was carried out between nanosheets and hydrogen peroxide solution to obtain V2CT. x -V2O x Material.

[0010] Preferably, the V2CT of the layer expansion process x The mass ratio of nanosheets to hydrogen peroxide is (75–88):1.

[0011] Preferably, the hydrothermal reaction temperature is 100–200°C, and the hydrothermal reaction time is 10–14 h.

[0012] Preferably, the inorganic strong base solution is an aqueous solution of NaOH; the molar concentration of the inorganic strong base solution is 5.5 × 10⁻⁶. -3 ~6.5×10 -3 mol / L.

[0013] Preferably, the multilayer V2CT x The preparation method of nanosheets includes the following steps:

[0014] V2AlC powder, NaF, and hydrochloric acid solution were mixed and subjected to a hydrothermal reaction to obtain multilayer V2CT. x The mass ratio of nanosheets, HCl, NaF and V2AlC powder is (800-900):(50-150):(50-100).

[0015] Preferably, the hydrothermal reaction temperature is 80–100°C, and the hydrothermal reaction time is 70–80 h.

[0016] This invention provides the V2CT described in the above technical solution. x -V2O x V2CT prepared by the material or the preparation method described in the above technical solution x -V2O x Application of the material in the preparation of cathode materials for aqueous zinc-ion batteries.

[0017] This invention provides a V2CT x -V2O x Positive electrode material, including the V2CT described in the above technical solution. x -V2O x V2CT prepared by the material or the preparation method described in the above technical solution x -V2O x Materials, conductive agents, and adhesives; the V2CT x -V2O x The mass ratio of the material, conductive agent, and binder is (5-10):(1-5):(0.5-1.5).

[0018] This invention provides a V2CT x -V2O x The positive electrode includes a conductive substrate and a conductive coating disposed on the surface of the conductive substrate, wherein the conductive coating is the V2CT described in the above technical solution. x -V2O x Positive electrode material.

[0019] This invention provides a V2CT x -V2O x Materials, including multi-slice V2CT x Nanosheets and grown in the multilayer V2CT x V2O on the surface of the layered structure of nanosheets x The V2CT provided by this invention x -V2O x Materials in multi-layer V2CT x V2O grown on the surface of nanosheet sheet structure x vanadium-based oxides (V₂O) x The formation of Zn weakens the electrostatic interactions between materials and increases the concentration of Zn. 2+ The conductive channels allow for increased battery capacity; additionally, V2O xThe layered structure distributed on the surface of V2C enhances the stability of the material structure, inhibits the dissolution of the bulk material during cycling, and thus extends the battery's lifespan. In summary, this invention achieves V2O with a relatively large interlayer spacing. x With multi-slice V2CT x The synergistic effect of nanosheets results in excellent electrochemical performance. The V2CT provided by this invention... x -V2O x When the material is applied to the cathode of an aqueous zinc-ion battery, at 0.05 A·g -1 It provides 224 mAh·g at a current density. -1 Excellent specific capacity, when the power density is 38.7 W·kg -1 Energy density up to 174 Wh·kg -1 Meanwhile, the V2CT of the present invention x -V2O x The material exhibits excellent cycle performance, maintaining a capacity retention of up to 92% at high current density after 200 charge-discharge cycles. This invention inspires the development direction of aqueous zinc-ion battery cathodes and provides a reliable strategy for the development of next-generation new energy sources.

[0020] This invention provides the V2CT described in the above technical solution. x -V2O x The method for preparing the material includes the following steps: multilayer V2CT x Nanosheets were mixed with an inorganic strong alkali solution and subjected to alkali-based layer expansion treatment to obtain alkali-treated V2CT. x Nanosheets; V2CT treated with alkali x A hydrothermal reaction was carried out between nanosheets and hydrogen peroxide solution to obtain V2CT. x -V2O x Materials. In this invention, a simple hydrothermal method is used to fabricate multilayer V2CT. x After alkalization and subsequent oxidation, the nanosheets can be directly applied to V2CT. x V2O grows on the surface of nanosheets x V2CT was obtained x -V2O x Materials. The preparation method provided by this invention is simple, highly reproducible, and features high safety, good stability, no pollution, and environmental friendliness, making it suitable for commercial application. Attached Figure Description

[0021] Figure 1 This invention uses V2CT x -V2O x A structural diagram of an aqueous zinc-ion battery with the positive electrode as the cathode.

[0022] Figure 2V2CT, the positive electrode material prepared in Example 1 of this invention. x -V2O x XRD pattern of nanosheets;

[0023] Figure 3 V2CT, the positive electrode material prepared in Example 1 of this invention. x -V2O x TEM image of nanosheets;

[0024] Figure 4 V2CT, the positive electrode material prepared in Example 1 of this invention. x -V2O x SEM image of nanosheets;

[0025] Figure 5 V2CT, the positive electrode material prepared in Example 1 of this invention. x -V2O x Electrode rate performance diagram;

[0026] Figure 6 V2CT, the positive electrode material prepared in Example 1 of this invention. x -V2O x Electrode cycle performance diagram;

[0027] Figure 7 V2CT, the positive electrode material prepared in Example 1 of this invention. x -V2O x Ragone diagram of the electrodes;

[0028] Figure 8 V2CT, the positive electrode material prepared in Example 1 of this invention. x -V2O x The electrode is in the range of 0.05-2.0 A·g -1 The constant current charge-discharge curves at current densities;

[0029] Figure 9 V2CT, the positive electrode material prepared in Example 1 of this invention. x -V2O x The CV curves of the electrode at different scan rates and the relationship between log(i) and log(v) of the current response;

[0030] Figure 10 V2CT, the positive electrode material prepared in Example 1 of this invention. x -V2O x Electrode galvanostatic intermittent titration (GITT) test graph and Nyquist (EIS) plot after different charge-discharge cycles;

[0031] Figure 11 V2CT provided by the present invention x-V2O x Schematic diagram of the reaction principle of the material as a positive electrode material;

[0032] Figure 12 V2CT, the cathode material prepared in Example 12 x -V2O x Nanosheets at 0.05 A·g -1 Specific capacity plot at current density;

[0033] Figure 13 V2CT, the cathode material prepared in Example 12 x -V2O x A graph showing the relationship between power density and energy density of nanosheets;

[0034] Figure 14 V2CT, the cathode material prepared in Example 12 x -V2O x Graph of nanosheets after 200 charge-discharge cycles;

[0035] Figure 15 V2CT prepared in Example 1 of the present invention x Electron micrograph of nanosheets. Detailed Implementation

[0036] This invention provides a V2CT x -V2O x Materials, including multi-slice V2CT x Nanosheets and grown in the multilayer V2CT x V2O on the surface of the layered structure of nanosheets x .

[0037] In this invention, unless otherwise specified, all raw materials / components used in the preparation are commercially available products well known to those skilled in the art.

[0038] The V2CT provided by this invention x -V2O x Materials include multi-slice V2CT x Nanosheets. In this invention, the multilayer V2CT x The interlayer spacing of the nanosheets is preferably 400 nm to 1.5 μm.

[0039] The V2CT provided by this invention x -V2O x The material includes materials grown in the multilayer V2CT x V2O on the surface of the layered structure of nanosheets x In this invention, V2O x It is a vanadium-based oxide, in which the oxidation states of vanadium are +2, +3, +4 and +5.

[0040] This invention provides the V2CT described in the above technical solution. x -V2O x The method for preparing the material includes the following steps:

[0041] Multi-layer V2CT x Nanosheets were mixed with an inorganic strong alkali solution and subjected to alkali-based layer expansion treatment to obtain alkali-treated V2CT. x Nanosheets;

[0042] The alkalized V2CT x A hydrothermal reaction was carried out between nanosheets and hydrogen peroxide solution to obtain V2CT. x -V2O x Material.

[0043] This invention utilizes multilayer V2CT x Nanosheets and an inorganic strong alkali solution are mixed (hereinafter referred to as the first mixture) and subjected to alkali-induced layer expansion treatment to obtain alkali-treated V2CT. x Nanosheets.

[0044] In this invention, the multilayer V2CT x The preferred method for preparing nanosheets includes the following steps:

[0045] V2AlC powder, NaF, and hydrochloric acid solution were mixed (hereinafter referred to as the second mixture) and subjected to a hydrothermal reaction (hereinafter referred to as the first hydrothermal reaction) to obtain multilayer V2CT. x The mass ratio of nanosheets, HCl, NaF and V2AlC powder is (800-900):(50-150):(50-100).

[0046] In this invention, the mass percentage of the hydrochloric acid solution is preferably 35-38%. The mass ratio of HCl, NaF and V2AlC powder is preferably (800-900):(50-150):(50-100), more preferably (820-890):(55-145):(55-95), and even more preferably (830-880):(60-140):(60-90).

[0047] In this invention, the preferred order of the second mixing is: premixing NaF and hydrochloric acid solution to obtain a premixed solution; then mixing the V2AlC powder and the premixed solution. In this invention, the first mixing is preferably carried out under stirring conditions, and the stirring time is preferably 1–3 hours.

[0048] As one or more embodiments of the present invention, the preferred mass ratio of HCl, NaF and V2AlC powder is (800-830):(50-80):(50-60), and the first mixing time is 1.0-1.5 h.

[0049] As one or more embodiments of the present invention, the preferred mass ratio of HCl, NaF and V2AlC powder is (840-880):(90-110):(61-80), and the first mixing time is 1.5-2.4 h.

[0050] As one or more embodiments of the present invention, the preferred mass ratio of HCl, NaF and V2AlC powder is (880-900):(120-150):(80-100), and the first mixing time is 2.4-3.0 h.

[0051] In this invention, the temperature of the first hydrothermal reaction is preferably 80-100°C, more preferably 85-95°C; the time of the hydrothermal reaction is preferably 70-80h, more preferably 72-78h.

[0052] As one or more embodiments of the present invention, when the first hydrothermal reaction temperature is 80-85°C, the hydrothermal reaction time is 70-71h.

[0053] As one or more embodiments of the present invention, when the first hydrothermal reaction temperature is 85-90°C, the hydrothermal reaction time is 72-75 h.

[0054] As one or more embodiments of the present invention, when the first hydrothermal reaction temperature is 90-100°C, the hydrothermal reaction time is 75-80 h.

[0055] In this invention, after the first hydrothermal reaction is completed, the obtained first hydrothermal reaction solution is preferably post-processed to obtain the multilayer V2CT. x Nanosheets. In this invention, the post-processing preferably includes the following steps: washing the solid product in the first hydrothermal reaction solution with water to obtain a neutral solid product; mixing the neutral solid product with ethanol and subjecting it to ultrasonic treatment to obtain an ultrasonically treated product; drying the ultrasonically treated product to obtain the multilayer V2CT. xNanosheets. In this invention, the water washing is preferably deionized water washing, preferably performed under centrifugation conditions, the centrifugation speed is preferably 5000-7000 rpm, the number of centrifugal washings is preferably 6-10 times, and the water washing is preferably performed until the pH of the supernatant after washing is neutral. In this invention, the mass ratio of the neutral solid product to the volume of ethanol is preferably (1.5-2.3) g:(40-50) mL. The ultrasonic power is preferably 220-230 W, and the ultrasonic time of ethanol is preferably 1-3 h. As one or more embodiments of this invention, when the mass ratio of the neutral solid product to the volume of ethanol is preferably (1.5-2.3) g:(40-42) mL, the ultrasonic time of ethanol is preferably 1-1.5 h. As one or more embodiments of this invention, when the mass ratio of the neutral solid product to the volume of ethanol is preferably (1.5-2.3) g:(43-46) mL, the ultrasonic time of ethanol is preferably 1.6-2 h. As one or more embodiments of the present invention, the mass ratio of the neutral solid product to the volume of ethanol is preferably (1.5-2.3) g:(47-50) mL, and the ultrasonication time of ethanol is preferably 2.1-3 h.

[0056] In this invention, the drying is preferably freeze-drying, and the freeze-drying temperature is preferably -50 to -70°C, and the freeze-drying time is preferably 40 to 50 hours. As one or more embodiments of this invention, the freeze-drying temperature is -50 to -59°C, and the freeze-drying time is 40 to 44 hours. As one or more embodiments of this invention, the freeze-drying temperature is -60 to -65°C, and the freeze-drying time is 45 to 47 hours. As one or more embodiments of this invention, the freeze-drying temperature is -66 to -70°C, and the freeze-drying time is 48 to 50 hours.

[0057] In this invention, the inorganic strong base solution is preferably an aqueous solution of NaOH; the molar concentration of the inorganic strong base solution is preferably 5.5 × 10⁻⁶. -3 ~6.5×10 -3 mol / L, more preferably 5.8 × 10 mol / L. -3 ~6.2×10 -3 mol / L. In this invention, the first mixing is preferably a multilayer V2CT. x The nanosheets are added to an inorganic strong alkaline solution. The alkaline layer-expansion treatment is carried out under stirring conditions, and the preferred treatment time is 10–14 hours. The temperature for the alkaline layer-expansion treatment is room temperature.

[0058] As one or more embodiments of the present invention, the molar concentration of the inorganic strong base solution is 5.5 × 10⁻⁶. -3 ~5.8×10 -3The concentration is mol / L, and the alkaline layer expansion treatment time is 10-11 h.

[0059] As one or more embodiments of the present invention, the molar concentration of the inorganic strong alkali solution is 5.9 × 10⁻⁶. -3 ~6.2×10 -3 The concentration is mol / L, and the alkaline layer expansion treatment time is 12-13 h.

[0060] As one or more embodiments of the present invention, the molar concentration of the inorganic strong base solution is 6.3 × 10⁻⁶. -3 ~6.5×10 -3 The concentration is mol / L, and the alkaline layer expansion treatment time is 13-14 h.

[0061] In this invention, after the alkaline layer expansion treatment is completed, the obtained alkaline treatment solution is preferably post-treated to obtain alkaline-treated V2CT. x Nanosheets. In this invention, the post-processing preferably includes the following steps: washing the solid product in the alkalization treatment solution with water to obtain a neutral alkalization treatment product; drying the neutral alkalization treatment product to obtain alkalized V2CT. x Nanosheets. In this invention, the washing is preferably deionized water washing, preferably performed under centrifugation conditions, the centrifugation speed is preferably 3000-4000 rpm, the number of centrifugal washing cycles is preferably 5-8, and the washing is preferably performed until the pH of the supernatant after washing is neutral. In this invention, the drying is preferably freeze-drying, the freeze-drying temperature is preferably -50 to -70°C, and the time is preferably 40-50 hours.

[0062] V2CT that has undergone alkalization treatment x Following the nanosheets, the present invention applies the alkalized V2CT. x Nanosheets and hydrogen peroxide solution are mixed (hereinafter referred to as the third mixture) and subjected to a hydrothermal reaction (hereinafter referred to as the second hydrothermal reaction) to obtain V2CT. x -V2O x Material.

[0063] In this invention, the V2CT with layer expansion processing x The preferred mass ratio of nanosheets to hydrogen peroxide is (75–88):1, more preferably (75–87.5):1. In this invention, the third mixture is preferably alkalized V2CT. x Nanosheets are added to a hydrogen peroxide solution. This invention does not have specific requirements regarding the mass content of hydrogen peroxide in the solution, ensuring that the H2O2 in the hydrogen peroxide aqueous solution is in harmony with the V2CT obtained from the layer-expansion treatment. x Nanosheets can be within the above-mentioned mass ratio range.

[0064] In this invention, the temperature of the second hydrothermal reaction is preferably 100-200°C, more preferably 120-160°C; the time of the second hydrothermal reaction is preferably 10-14 hours, more preferably 11-13 hours.

[0065] In this invention, the V2CT with layer expansion processing x The mass ratio of nanosheets to hydrogen peroxide cannot be too high or too low; V2CT with layer expansion treatment x When the mass ratio of nanosheets to hydrogen peroxide is too high, the amount of hydrogen peroxide used is too low, which is insufficient for V2CT. x Sufficient V2O is formed on the surface of the nanosheet's layered structure. x (vanadium-based oxides) lead to the final V2CT x -V2O x The material has poor electrochemical performance; V2CT with layer expansion treatment x When the mass ratio of nanosheets to hydrogen peroxide is too small, the amount of hydrogen peroxide used is too large, leading to V2CT. x The nanosheets were largely oxidized to vanadium pentoxide, making it impossible to form V2CT. x Nanosheet-loaded V2O x The structure of the (vanadium-based oxide) also leads to a deterioration in the electrochemical performance of the product. The preparation method provided by this invention effectively controls the V2CT of the layer-expansion process. x When the mass ratio of nanosheets to hydrogen peroxide is within a reasonable range, the effect of hydrogen peroxide on V2CT can be achieved. x Effective oxidation of the nanosheet layered structure surface, resulting in in-situ growth of V2O on the nanosheet surface. x (Vanadium-based oxides) not only increase the interlayer spacing of nanosheet structures, but also enable them to interact with V2CT. x Synergistic effect of active functional groups in nanosheets to improve V2CT x Electrochemical properties of nanosheets.

[0066] In this invention, after the second hydrothermal reaction is completed, the hydrothermal reaction solution cooled to room temperature is preferably post-treated to obtain V2CT. x -V2O x Materials. In this invention, the post-processing preferably includes the following steps: washing the solid product in the second hydrothermal reaction solution with water to obtain a neutral solid product; drying the neutral solid product to obtain V2CT. x -V2O xMaterials. In this invention, the water washing is preferably deionized water washing, and the water washing is preferably carried out under centrifugation conditions. The centrifugation speed is preferably 5000-7000 rpm, and the number of centrifugal washings is preferably 2-3 times. The water washing is preferably performed until the pH value of the supernatant after washing is neutral. In this invention, the drying is preferably freeze-drying, and the freeze-drying temperature is preferably -50 to -70°C, and the time is preferably 40-50 hours.

[0067] This invention provides the V2CT described in the above technical solution. x -V2O x V2CT prepared by the material or the preparation method described in the above technical solution x -V2O x Application of the material in the preparation of cathode materials for aqueous zinc-ion batteries.

[0068] This invention provides a V2CT x -V2O x Positive electrode material, including the V2CT described in the above technical solution. x -V2O x V2CT prepared by the material or the preparation method described in the above technical solution x -V2O x Conductive agent and adhesive; the V2CT x -V2O x The mass ratio of the material, conductive agent, and binder is (5-10):(1-5):(0.5-1.5).

[0069] In this invention, the conductive agent is preferably acetylene black. The binder is preferably polyvinylidene fluoride.

[0070] As one or more embodiments of the present invention, the V2CT x -V2O x The mass ratio of the material, conductive agent, and binder is (5-6):(1-2):(0.5-0.8).

[0071] As one or more embodiments of the present invention, the V2CT x -V2O x The mass ratio of the material, conductive agent, and binder is (7-8):(2-3):(0.9-1.2).

[0072] As one or more embodiments of the present invention, the V2CT x -V2O x The mass ratio of the material, conductive agent, and binder is (9-10):(4-5):(1.3-1.5).

[0073] This invention provides a V2CTx -V2O x The positive electrode includes a conductive substrate and a conductive coating disposed on the surface of the conductive substrate, wherein the conductive coating is the V2CT described in the above technical solution. x -V2O x Positive electrode material.

[0074] The V2CT provided by this invention x -V2O x The positive electrode includes a conductive substrate. In this invention, the conductive substrate is preferably a titanium sheet.

[0075] This invention provides the V2CT described in the above technical solution. x -V2O x The method for preparing the positive electrode includes the following steps:

[0076] The V2CT described in the above technical solution x -V2O x V2CT prepared by the material or the preparation method described in the above technical solution x -V2O x Materials, conductive agents, binders, and organic solvents are mixed to obtain a conductive paste;

[0077] The conductive paste is coated onto the surface of a conductive substrate and dried to obtain the V2CT. x -V2O x positive electrode.

[0078] The present invention utilizes the V2CT described in the above technical solution. x -V2O x V2CT prepared by the material or the preparation method described in the above technical solution x -V2O x Materials, conductive agents, adhesives, and organic solvents are mixed to obtain a conductive paste. In this invention, the organic solvent is preferably N-methylpyrrolidone (NMP). This invention does not have special requirements on the amount of organic solvent used, as long as it ensures that the obtained conductive paste can be smoothly coated.

[0079] After obtaining the conductive paste, the present invention coats the conductive paste onto the surface of a conductive substrate and dries it to obtain the V2CT. x -V2O x positive electrode.

[0080] The present invention does not specify the particular process for the coating. In this invention, the drying is preferably vacuum drying. The drying temperature is preferably 50–70°C, and the drying time is preferably 9–12 hours.

[0081] As one or more embodiments of the present invention, when the drying temperature is 50°C, the drying time is 9 to 10 hours.

[0082] As one or more embodiments of the present invention, when the drying temperature is 60°C, the drying time is 11 to 12 hours.

[0083] As one or more embodiments of the present invention, when the drying temperature is 70°C, the drying time is 10 to 11 hours.

[0084] In this invention, the V2CT is described. x -V2O x The positive electrode is preferably used as the positive electrode in aqueous zinc-ion batteries.

[0085] The V2CT provided by this invention x -V2O x Materials, multi-layer V2CT x Nanosheets are accordion-like layered materials with large interlayer spacing, which facilitates the processing of Zn. 2+ Embedding and extraction. In V2CT x V2O was grown on the surface of the layered structure of nanosheets using a hydrothermal method. x It can be used as a positive electrode material in aqueous zinc-ion batteries. When applied to aqueous zinc-ion batteries, at 0.05 A·g -1 It provides 224 mAh·g at a current density -1 Excellent specific capacity, when the power density is 38.7 W·kg -1 Energy density up to 174 Wh·kg -1 The cathode material of this invention also exhibits better cycle performance, maintaining a capacity retention of up to 92% after 200 charge-discharge cycles.

[0086] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0087] Example 1

[0088] 1) Add 2.0g NaF to 40mL hydrochloric acid (mass percentage 35%) and stir on a magnetic stirrer for 10min (600rpm) until completely dissolved to obtain a mixed solution of NaF and HCl; then add 1.5g V2AlC to the above mixed solution of NaF and HCl and stir for 2.0h (600rpm) to obtain a precursor solution;

[0089] 2) The precursor solution obtained in step 1) is transferred to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) for hydrothermal reaction at a temperature of 90°C for 72 hours. After the reactor cools down, the hydrothermal reaction solution is obtained. The solid product obtained by centrifuging the hydrothermal reaction solution is V2CT. x Nanosheet precursor;

[0090] 3) The V2CT obtained in step 2) x The nanosheet precursor was first washed with deionized water (centrifuged at 5000 rpm until the pH of the supernatant became neutral). Then, 2.0 g of the product was sonicated in 45 mL of ethanol for 2.0 h to remove incompletely etched V2AlC phase material. After centrifugation, it was freeze-dried at -60 °C for 48 h to obtain V2CT. x Nanosheets (electron micrographs, e.g.) Figure 15 (as shown);

[0091] 4) The V2CT obtained in step 3) x Nanosheet powder with 6×10 -3 After stirring the NaOH solution of M at room temperature for 12 hours (600 rpm), centrifuge and wash (4000 rpm, centrifuge and wash until the pH of the supernatant is neutral), and freeze-dry at -60°C for 48 hours, alkalized V2CT is obtained. x Nanosheets;

[0092] 5) Add 1.8g of alkalized V2CT x The nanosheets were placed in 40 mL of H2O2 solution (after alkalization of V2CT). x Nanosheets and H2O2 (mass ratio 75:1) were stirred vigorously for 1.0 h (700 rpm) and then transferred to a high-pressure reactor. The mixture was reacted at 180 °C for 12 h. After cooling to room temperature, the mixture was centrifuged and washed (4000 rpm until the pH of the supernatant was neutral). Finally, it was freeze-dried at -60 °C for 48 h to obtain V2CT. x -V2O x Material.

[0093] 6) Take the 1.6g V2CT obtained in step 5). x -V2O x The material, along with acetylene black and polyvinylidene fluoride, was uniformly mixed in 1 mL of NMP to obtain a slurry. This slurry was then coated onto a titanium sheet and dried in a vacuum drying oven. V2CT was involved in this process. x -V2O x The mass ratio of nanosheets, acetylene black, and polyvinylidene fluoride was 7:2:1; the drying temperature was 60℃, and the drying time was 12 hours. V2CT was thus prepared.x -V2O x positive electrode.

[0094] V2CT was prepared in this embodiment. x -V2O x Performance testing of the positive electrode as the positive electrode in aqueous zinc-ion batteries:

[0095] Electrochemical performance testing:

[0096] Test method: The V2CT prepared in the example was tested using an electrochemical workstation. x -V2O x The electrochemical performance of the positive electrode. Among them, Figure 1 This invention uses V2CT x -V2O x This is a structural diagram of an aqueous zinc-ion battery with the positive electrode as the cathode.

[0097] Cyclic voltammetry (CV): Attach the green clamp of the electrochemical workstation to one side of the working electrode of the assembled battery, and the red clamp (counter electrode) and white clamp (reference electrode) to the other electrode. Then select the CV test function and enter the parameter settings. The parameters to be set include: initial potential 0.15V, upper limit potential 1.7V, lower limit potential 0.15V, endpoint potential 1.7V, initial scan direction, scan speed 0.0005V / s, number of scan segments (2 segments per cycle), sampling interval 0.001V, resting time 2s, sensitivity instrument, and operating mode. The voltage is scanned from the initial potential to the upper limit potential and then to the lower limit potential. The slope of the voltage versus time is the scan speed. Finally, a closed curve is formed, representing the redox reaction occurring at the electrode in the electrochemical system.

[0098] Constant Current Charge-Discharge (GCD) Method: The electrode clamping method is the same as CV. Select the GCD test function to enter the parameter settings. Parameters to be tested include cathode current, anode current, charging cut-off voltage, discharging cut-off voltage, and number of cycles. Under constant current conditions, charge and discharge operations are performed on the electrode under test, and the change in its potential over time is recorded to study the charge-discharge performance of the electrode and calculate its actual specific capacity. During the charge-discharge experiment under constant current conditions, the electrochemical response signal of the controlled current is used. When the current control signal is applied, the potential is the measured response signal, mainly studying the change in potential as a function of time.

[0099] Electrochemical Impedance Spectroscopy (EIS): Electrode clamping method is the same as CV. Select the EIS test function to enter parameter settings. Set the frequency at high frequency to 100 kHz and the frequency at low frequency to 10 mHz. Use the default values ​​for amplitude and settling time.

[0100] Intermittent galvanostatic titration (GITT): The electrode clamping method is the same as CV. GITT first applies a positive current pulse, causing the battery potential to rise rapidly, proportional to the iR voltage. Here, R is the internal resistance of the entire system, including the uncompensated resistance Run and the charge transfer resistance Rct. Subsequently, the charging current is maintained constant, causing the potential to rise slowly. This is the origin of the "constant current" in GITT. At this point, the relationship between the potential E and time t needs to be described using Fick's second law. Fick's first law only applies to steady-state diffusion, i.e., the concentration of the diffusing component varies only with distance, not with time. In reality, most diffusion processes occur under non-steady-state conditions. For non-steady-state diffusion, Fick's second law must be applied. Next, the charging current is interrupted, and the potential drops rapidly, the decrease being proportional to the iR voltage. Finally, a relaxation process begins. During this relaxation, through zinc ion diffusion, the composition in the electrode tends to become homogeneous, and the potential drops slowly until equilibrium is reached again. Repeat the above process: pulse, constant current, relaxation, pulse, constant current, relaxation, until the battery is fully charged. The discharging process is the reverse of the charging process.

[0101] V2CT prepared in Example 1 x -V2O x The electrode is used as the positive electrode, a 100 μm thick zinc foil is used as the negative electrode, and the concentration is 3 mol / L. -1 The electrochemical performance of Zn(CF3SO3)2 aqueous solution was tested using it as electrolyte.

[0102] In Example 1, V2CT was used x -V2O x The structure diagram of an aqueous zinc-ion battery with the positive electrode is shown below. Figure 1 As shown. The V2CT fabrication process was performed. x -V2O x XRD pattern of nanosheets as shown Figure 2 As shown in the XRD pattern, V2CT x -V2O x The 002 peak appears around 7°, which, according to Bragg's formula, indicates that V2CT... x -V2O x It has a large inter-layer distance. V2CT x -V2O x TEM images of nanosheets are as follows Figure 3 As shown, V2O can be clearly seen. x Elements are uniformly dispersed in V2CT x On nanosheets. V2CT x -V2O x The morphology of the nanosheets is shown in the figure. Figure 4 As shown, V2CT x -V2O x It has an accordion-like shape. (V2CT)x -V2O x The rate performance diagram of the electrode is shown below. Figure 5 As shown, when the current density increases from 0.05 A·g -1 Increased to 2.0 A·g -1 The capacity gradually decreases until the current density returns to 0.1 A·g. -1 Its capacity can return to a value comparable to its original value, demonstrating V2CT. x -V2O x The electrodes exhibit excellent rate performance. V2CT x -V2O x The cycle performance diagram of the electrode is shown below. Figure 6 As shown, after 200 charge-discharge cycles, the capacitance retention rate is as high as 92%. Figure 7 For the comparison of the energy density of this invention with other previously reported cathode materials, wherein, Figure 7 As shown, other reported cathode materials include: Na3V2(PO4)2F3, CuHCF, Na3V2(PO4)3, H2V3O8, Zn3[Fe(CN)6]2(ZnHCF), Na 0.95 MnO2, Fe(CN)6, VS2, the above materials were used to prepare the cathode using V2CT, similar to Example 1. x -V2O x The methods for preparing the positive electrode are the same, and the assembly methods for aqueous zinc-ion batteries are also the same. Under different power densities, the positive electrode prepared in Embodiment 1 of this invention exhibits a higher energy density, which can be seen in the range of 0.05–2.0 A·g. -1 At current density, using V2CT x -V2O x The energy density of the electrodes is superior to that of batteries using other cathode materials. V2CT x -V2O x The GCD curves of the electrode at different current densities are as follows: Figure 8 As shown, V2CT can be seen from the GCD image. x -V2O x The electrodes exhibit high charge / discharge specific capacity, due to Figure 8 It can be obtained that at 0.05 A·g -1 At a current density of 200 mAh·g, its specific capacity can reach 200 mAh·g. -1 V2CT x -V2O x CV curves of the electrode at different scan rates are as follows Figure 9 As shown in (a) above, based on Figure 9 The linear plots of log(i) and log(v) of the current response at the four peaks in (a) are shown below. Figure 9As shown in (b), according to the power law, the measured current (i) and the scanning rate (v) follow an empirical relationship: i = av b Here, a and b are adjustable parameters. The value of b can be obtained from the slope of the log(i) versus log(v) curve, thus providing insight into the energy storage mechanism. When the value of b is close to 0.5, it indicates a diffusion-controlled process; when the value of b is close to 1, it indicates that the electrochemical reaction is controlled by a surface capacitance-controlled process. Figure 9 (b) shows that the b-values ​​of the four peaks are 0.70 and 0.66 for the oxidation peaks and 0.68 and 0.67 for the reduction peaks. This indicates that Zn... 2+ In V2CT x -V2O x The electrochemical behavior involves both diffusion-controlled and surface capacitance-controlled processes. Intermittent galvanostatic titration (GITT) is used to test this process. Figure 10 As shown in (a) above, the Nyquist curve (EIS) is as follows: Figure 10 As shown in (b), the experimental results indicate that V2CT during charging and discharging... x -V2O x The electrode has a large diffusion kinetics and excellent conductivity.

[0103] The V2CT for aqueous zinc-ion batteries prepared by this invention x -V2O x The positive electrode has the advantages of simple manufacturing, low cost, and high specific capacity.

[0104] Example 2

[0105] Similar to Example 1, except that in step 1), the mass ratio of HCl:NaF:V2AlC is 830:70:55, and the stirring time is 1.2h.

[0106] Example 3

[0107] Similar to Example 1, except that in step 1), the mass ratio of HCl:NaF:V2AlC is 885:130:90, and the stirring time is 2.5h.

[0108] Example 4

[0109] Similar to Example 1, except that in step 2), the hydrothermal reaction temperature is 80°C and the hydrothermal reaction time is 70 hours.

[0110] Example 5

[0111] Similar to Example 1, except that in step 2), the hydrothermal reaction temperature is 95°C and the hydrothermal reaction time is 80 hours.

[0112] Example 6

[0113] Similar to Example 1, except that in step 3), the mixture is sonicated in 42 mL of ethanol for 1.0 h.

[0114] Example 7

[0115] Similar to Example 1, except that in step 3), the mixture is sonicated in 47 mL of ethanol for 2.7 h.

[0116] Example 8

[0117] Similar to Example 1, except that in step 4), the freeze-drying temperature is -55°C.

[0118] Example 9

[0119] Similar to Example 1, except that in step 4), the freeze-drying temperature is -65°C.

[0120] Example 10

[0121] Similar to Example 1, except that in step 5), the stirring time is 10 hours.

[0122] Example 11

[0123] Similar to Example 1, except that in step 5), the stirring time is 14 hours.

[0124] Example 12

[0125] Similar to Example 1, except that in step 6), V2CT x The mass ratio of H2O2 was 87.5:1, and the hydrothermal reaction time was 10 hours.

[0126] The electrochemical performance test results of Example 12 are as follows: Figures 12-14 As shown. Figure 12 As shown, the cathode material prepared in Example 12 was subjected to a reaction at 0.05 A·g. -1 It provides 164 mAh·g at a current density -1 Excellent specific capacity. For example... Figure 13 As shown, the cathode material prepared in Example 12 has a power density of 38.7 W·kg⁻¹. -1 Energy density up to 126Wh·kg -1 .like Figure 14 As shown, the cathode material prepared in Example 12 retains a capacity of up to 75% after 200 charge-discharge cycles.

[0127] Example 13

[0128] Similar to Example 1, except that in step 6), V2CTx The mass ratio of H2O2 was 80:1, and the hydrothermal reaction time was 14 hours.

[0129] Example 14

[0130] Similar to Example 1, except that in step 7), V2CT x -V2O x The mass ratio of nanosheets, acetylene black, and polyvinylidene fluoride is 6:1:0.5.

[0131] Example 15

[0132] Similar to Example 1, except that in step 7), V2CT x -V2O x The mass ratio of nanosheets, acetylene black, and polyvinylidene fluoride is 8:3:1.5.

[0133] Example 16

[0134] Similar to Example 1, except that in step 7), the drying temperature is 55°C and the drying time is 9.0 h.

[0135] Example 17

[0136] Similar to Example 1, except that in step 7), the drying temperature is 65°C and the drying time is 11 hours.

[0137] In the technical solutions of this invention, although some optimal values ​​are given in the embodiments, such as adding 2.0g of NaF to 40mL of HCl when preparing a NaF and HCl mixed solution, this invention is not limited to the mass of NaF and the volume of HCl given in the above embodiments. The specific mass of NaF and the volume of HCl should be determined according to actual needs. For example, the embodiments give optimal drying times, but this invention is not limited to the drying times given in the above embodiments. Since the drying time is 9-12h, 12h can be used, or 9h, 10h, etc. can also be used, but the time should not be too short. The specific drying time needs to be determined according to actual needs.

[0138] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A V2CT x -V2O x The method for preparing the material is characterized by, Includes the following steps: Multi-layer V2CT x Nanosheets were mixed with an inorganic strong alkali solution and subjected to alkali-based layer expansion treatment to obtain alkali-treated V2CT. x The time for the alkaline layer expansion treatment of the nanosheets is 10-14 hours; The alkalized V2CT x A hydrothermal reaction was carried out between nanosheets and hydrogen peroxide solution to obtain V2CT. x -V2O x Material, the alkalized V2CT x The mass ratio of nanosheets to hydrogen peroxide is (75~88):1; the V2CT x -V2O x Materials include multi-slice V2CT x Nanosheets and grown in the multilayer V2CT x V2O on the surface of the layered structure of nanosheets x .

2. The preparation method according to claim 1, characterized in that, The hydrothermal reaction temperature is 100~200℃, and the hydrothermal reaction time is 10~14 h.

3. The preparation method according to claim 1, characterized in that, The inorganic strong base solution is an aqueous solution of NaOH; the molar concentration of the inorganic strong base solution is 5.5 × 10⁻⁶. -3 ~6.5×10 -3 mol / L.

4. The preparation method according to claim 2, characterized in that, The multilayer V2CT x The preparation method of nanosheets includes the following steps: V2AlC powder, NaF, and hydrochloric acid solution were mixed and subjected to a hydrothermal reaction to obtain multilayer V2CT. x The mass ratio of nanosheets, HCl, NaF and V2AlC powder is (800~900):(50~150):(50~100).

5. The preparation method according to claim 4, characterized in that, The hydrothermal reaction temperature is 80~100℃, and the hydrothermal reaction time is 70~80h.

6. The V2CT prepared by the preparation method according to any one of claims 1 to 5 x -V2O x Application of the material in the preparation of cathode materials for aqueous zinc-ion batteries.

7. A V2CT x -V2O x The cathode material is characterized by, The V2CT includes those prepared by the preparation method according to any one of claims 1 to 5. x -V2O x Materials, conductive agents, and adhesives; the V2CT x -V2O x The mass ratio of the material, conductive agent, and binder is (5~10):(1~5):(0.5~1.5).

8. A V2CT x -V2O x Positive electrode, characterized in that, It includes a conductive substrate and a conductive coating disposed on the surface of the conductive substrate, wherein the conductive coating is the V2CT as described in claim 7. x -V2O x Positive electrode material.

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