A kind of H6V4O 10 Preparation of MXene cathode materials and their application in aqueous zinc-ion batteries

Abstract

The present invention discloses a H6V4O 10 / Preparation of MXene cathode materials and their application in aqueous zinc-ion batteries, H6V4O 10 The preparation method of MXene cathode material comprises the following steps: dissolving vanadium pentoxide and ascorbic acid in deionized water to form a mixed solution, then adding MXene to the mixed solution to obtain a mixture, and then subjecting the mixture to a hydrothermal reaction, and washing and drying the obtained precipitate to obtain H6V4O 10 / MXene positive electrode material. The present invention adopts MXene and H6V4O 10 Composite method for H6V4O 10 Modification is carried out due to H6V4O 10 It will grow on the surface of MXene to form a heterojunction, which increases the H6V4O 10 conductivity and structural stability, while also shortening the Zn 2+ The diffusion distance of Zn 2+ transport kinetics, improving the capacity and stability of aqueous zinc-ion batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of battery materials, in particular to a H6V4O 10 Preparation of MXene cathode materials and their application in aqueous zinc-ion batteries. Background Art

[0002] Lithium-ion batteries and aqueous zinc-ion batteries have important application prospects in large-scale energy storage due to their high energy density, low cost and high safety. Among them, aqueous zinc-ion batteries are a battery system that uses water as an electrolyte solvent, in which zinc is used as the negative electrode material, and the positive electrode uses a material that can embed and deintercalate zinc ions. This type of battery has attracted attention due to its high safety, low cost, environmental friendliness and good electrochemical performance. The positive electrode material is one of the key factors that determine the performance of aqueous zinc-ion batteries. With the deepening of research, a variety of materials have been explored for the positive electrode of aqueous zinc-ion batteries, such as manganese-based oxides, vanadium-based compounds, polyanionic compounds, organic materials, etc.

[0003] Hailong Fei published a paper titled "Solvo-Thermal Synthesis of H6V4O 10 Microspheres as Stable Electrode Materials for Lithium and Zinc-ion Batteries (Int. J. Electrochem. Sci., 14 (2019) 11560-11570) (solvothermal synthesis of H6V4O 10 Microspheres and their application in lithium and zinc battery electrode materials) disclose a new electrode material H6V4O 10 Microspheres, first synthesized H6V4O using mixed solvent (PEG400+ethylene glycol) 10 Microspheres, the surface morphology can be controlled by regulating the solvent viscosity. The synthesized morphologies include loose nanoparticles and dense microblocks. H6V4O synthesized by solvent thermal method 10 Microspheres (especially nanoparticles) exhibit high capacity in lithium / zinc-ion batteries, which is mainly attributed to their unique surface structure and advantageous hydrogen content.

[0004] Although the H6V4O 10 The microspheres have a higher capacity, but the general H6V4O prepared without mixed solvents 10 However, the material has serious dissolution problems during the actual application research process. Its microstructure collapses after long-term use, which ultimately reduces the battery capacity and the battery's cycle stability. Summary of the Invention

[0005] The purpose of the present invention is to provide a H6V4O 10 Preparation of MXene cathode materials and their application in aqueous zinc ion batteries to solve the above-mentioned general H6V4O 10 The problem of long-term use of materials causing microstructure collapse and leading to a simultaneous decrease in battery capacity and cycle stability.

[0006] To achieve the above object, the present invention provides a H6V4O 10 / A method for preparing a MXene cathode material comprises the following steps:

[0007] Vanadium pentoxide and ascorbic acid are dissolved in deionized water to form a mixed solution, and then Mxene is added to the mixed solution to obtain a mixture. The mixture is then subjected to a hydrothermal reaction, and the obtained precipitate is washed and dried to obtain H6V4O 10 / MXene positive electrode material.

[0008] Preferably, the mass ratio of vanadium pentoxide to ascorbic acid is 1:0.8-1.0, and the mass volume ratio of vanadium pentoxide to deionized water is 0.8-1.2 g:40 mL.

[0009] Preferably, Mxene is a multilayer Mxene or a single few-layer Mxene solution.

[0010] Preferably, the preparation method of multilayer Mxene is:

[0011] Ti3AlC2 was slowly poured into hydrofluoric acid, stirred and etched with Al in Ti3AlC2, and then repeatedly washed with deionized water until the pH was 6.8~7.5. After centrifugation and freeze-drying, multilayer MXene powder was obtained.

[0012] Preferably, the mass volume ratio of the multilayer MXene powder and the mixed solution is 0.03-0.05 g:40 mL.

[0013] Preferably, the preparation method of the single few-layer MXene solution is:

[0014] Lithium fluoride is added to hydrochloric acid and stirred in an ice-water bath to obtain a mixed solution. Ti3AlC2 is then slowly poured into the mixed solution, continuously stirred and etched, and then centrifuged and washed until the pH is 4.5-5.5. The upper layer of the solution is poured out and deionized water is added again. Argon is then introduced as a protective gas and ultrasonicated. Finally, the supernatant is collected by centrifugation to obtain a single-layer MXene solution.

[0015] Preferably, the single-layer Mxene solution is a single-layer Ti3C2T x Solution, solution concentration is 3~8mg•mL -1 .

[0016] Preferably, the volume ratio of the single few-layer MXene solution to the mixed solution is 5-10:40.

[0017] Preferably, the temperature of the hydrothermal reaction is 160-200° C., and the time is 20-30 h.

[0018] The second aspect of the present invention provides a H6V4O 10 / MXene positive electrode material, prepared by the above preparation method.

[0019] Preferably, the smaller particle size of the flake H6V4O 10 With MXene as the skeleton, the stacked growth is on the surface of MXene. 10 It also grows between the layers of multilayer MXene, expanding the interlayer spacing of the multilayer MXene and forming a porous structure.

[0020] The third aspect of the present invention provides a H6V4O 10 / Application of MXene cathode materials in aqueous zinc-ion batteries.

[0021] Therefore, the present invention adopts a H6V4O 10 The preparation of MXene cathode materials and their application in aqueous zinc-ion batteries have the following beneficial effects:

[0022] The present invention adopts Mxene and H6V4O 10 Composite method for H6V4O 10 Modification is carried out due to H6V4O 10 It will grow on the surface of MXene to form a heterojunction, which increases the H6V4O 10 conductivity and structural stability, while also shortening the Zn 2+ The diffusion distance of Zn 2+ transport kinetics, improving the capacity and stability of aqueous zinc-ion batteries.

[0023] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 (a) Ti3AlC2 and Ti3C2T x (b) H6V4O 10 / MXene and H6V4O 10 / XRD pattern of MXene-f;

[0025] Figure 2 (a) H6V4O 10 / MXene and (b) H6V4O10 XPS spectra of / MXene-f and detailed spectra of (cd) V 2p, O 1s, and (ef) Ti 2p;

[0026] Figure 3 (a) Ti3AlC2; (b) Ti3C2T x ; (c) H6V4O 10 / MXene-f; (d)H6V4O 10 / SEM image of MXene;

[0027] Figure 4 (a) H6V4O 10 / MXene; (b) H6V4O 10 Nitrogen adsorption-desorption curves of / MXene-f;

[0028] Figure 5 H6V4O 10 、H6V4O 10 / MXene and H6V4O 10 CV curves of / MXene-f;

[0029] Figure 6 H6V4O 10 、H6V4O 10 / MXene and H6V4O 10 GCD curve of / MXene-f;

[0030] Figure 7 H6V4O 10 、H6V4O 10 / MXene and H6V4O 10 / MXene-f rate performance test at different current densities;

[0031] Figure 8 H6V4O 10 、H6V4O 10 / MXene and H6V4O 10 / MXene-f at 1A·g -1 Long cycle performance test;

[0032] Figure 9 H6V4O 10 、H6V4O 10 / MXene and H6V4O 10 EIS curve of / MXene-f;

[0033] Figure 10 (a) H6V4O 10 GITT curve of / MXene-f; (b) Zn2+ Diffusion coefficient. DETAILED DESCRIPTION

[0034] The present invention will be further described below. It should be noted that this embodiment is based on the technical solution and provides a detailed implementation method and specific operation process, but the present invention is not limited to this embodiment.

[0035] Example 1

[0036] A kind of H6V4O 10 / A method for preparing a MXene cathode material comprises the following steps:

[0037] (1) Preparation of multilayer MXene: First, add 20 mL of hydrofluoric acid to a polytetrafluoroethylene beaker and stir slowly with a magnet. Then weigh 1.0000 g of Ti3AlC2 and slowly pour it into the hydrofluoric acid. Stir at 35 °C for 24 h to etch away the Al layer in Ti3AlC2. Then, wash repeatedly with deionized water until the pH is close to 7. After centrifugation to obtain the precipitate, freeze-dry it to obtain multilayer MXene powder.

[0038] (2) Prepared by hydrothermal method: First, 1g of vanadium pentoxide and 0.9684g of ascorbic acid were dissolved in 40mL of deionized water and vigorously stirred at 25℃ for 4h to form a dark green, uniform mixed solution. 0.0400g of multilayer MXene powder was added to the mixed solution, and then hydrothermal treatment was carried out at 180℃ for 24h. After multiple washings with deionized water and ethanol, the powder was collected and dried to obtain H6V4O 10 / MXene powder.

[0039] Example 2

[0040] A kind of H6V4O 10 / A method for preparing a MXene cathode material comprises the following steps:

[0041] (1) Preparation of single-layer Mxene solution: First, add 1.6000g of lithium fluoride to 20mL of 2mol / L hydrochloric acid and stir in an ice-water bath for 10min. Then weigh 1.0000g of Ti3AlC2 and slowly pour it into the mixture of lithium fluoride and hydrochloric acid. Continue stirring and etching for 24h. Then centrifuge and wash it several times until the pH is about 5. After pouring off the upper solution, add 30mL of deionized water and introduce argon as a protective gas. Then ultrasonicate the solution for 2h and finally spin it at 3500r•min. -1 The supernatant was collected to obtain a Ti3C2T3O ... x Solution, solution concentration is 5mg•mL -1, that is, a single few-layer Mxene solution.

[0042] (2) Prepared by hydrothermal method: First, 1g of vanadium pentoxide and 0.9684g of ascorbic acid were dissolved in 40mL of deionized water and vigorously stirred at 25℃ for 4h to form a dark green, uniform mixed solution. 8mL of single-layer MXene solution was added to the mixed solution, and then hydrothermal treatment was carried out at 180℃ for 24h. After multiple washings with deionized water and ethanol, the powder was collected and dried to obtain H6V4O 10 / Mxene-f powder.

[0043] Comparative Example 1

[0044] A kind of H6V4O 10 The method for preparing a positive electrode material comprises the following steps:

[0045] It was prepared by a hydrothermal method. First, 1 g of vanadium pentoxide and 0.9684 g of ascorbic acid were dissolved in 40 mL of deionized water and stirred vigorously at 25 ° C for 4 h to form a dark green, uniform mixed solution. The mixed solution was then hydrothermaled at 180 ° C for 24 h. After multiple washings with deionized water and ethanol, the powder was collected and dried to obtain H6V4O. 10 .

[0046] Test Example 1

[0047] The products prepared in the examples and comparative examples were characterized by XRD, XPS, SEM and BET. Figures 1 to 3 .

[0048] from Figure 1 It can be seen that Ti3AlC2 has strong diffraction peaks at 9.6°, 19.1° and 38.8°, which correspond to its (002), (004) and (104) crystal planes. After etching, the product shows obvious XRD diffraction peaks at 9.0°, 18.3°, 27.6° and 60.7°, which represent Ti3C2T x The (002), (006), (008) and (110) crystal planes of Ti3AlC2 were observed, which proved that MXene was successfully prepared after etching. Figure 1 (b) is H6V4O 10 / MXene and H6V4O 10 / MXene-f XRD spectrum, from which we can see that H6V4O after compounding MXene 10 There is no significant difference between its XRD diffraction peaks and those of the sample before compounding. XRD diffraction peaks appear at 18.58°, 22.07°, 29.68° and 36.83°, corresponding to H6V4O 10The (001), (-201), (400) and (111) crystal planes of the H6V4O 10 / MXene and H6V4O 10 There is no obvious MXene diffraction peak in the XRD pattern of / MXene-f, only the 10 A broad peak appeared in the range of 40°-45° for MXene-f, which proved that the introduction of a small amount of MXene did not change the H6V4O 10 The crystal structure of MXene is only introduced into H6V4O as a matrix material. 10 middle.

[0049] from Figure 2 It can be seen that compared with pure H6V4O 10 ,H6V4O 10 / MXene and H6V4O 10 / MXene-f both have a Ti XPS peak at 480 eV, and in the fine spectrum of Ti 2p, such as Figure 2 As shown in (e) and (f), the peaks at 454.8eV, 455.9eV and 457.5eV correspond to the C-Ti-O bond and C-Ti 2+ -(O / OH) and C-Ti 3+ -(O / OH), which is the same as the XPS spectrum of MXene, proving that a small amount of MXene was successfully compounded into the sample. Figure 2 (c) and (d) are H6V4O 10 / MXene and H6V4O 10 The XPS spectra of V 2p and O 1s of / MXene-f show that both have XPS peaks at 515.7eV and 516.6eV, corresponding to V 3+ and V 4+ , proves that H6V4O 10 However, in the XPS spectra of Ti 2p and V 2p, the samples showed XPS peaks at 458.5eV and 517.7eV, corresponding to TiO2 and V 5+ This is due to the oxidation of the MXene surface.

[0050] from Figure 3 It can be seen that the surface of the composite MXene is relatively rough, and the flake H6V4O 10 With MXene as the skeleton, H6V4O 10 The stacking grows on the surface of MXene. At the same time, the flake H6V4O 10It also grows between the layers of multilayer MXene, expanding the interlayer spacing of the multilayer MXene and forming a porous structure.

[0051] from Figure 4 As can be seen, BET proves H6V4O 10 / MXene materials and H6V4O 10 / MXene-f materials all have mesoporous structures, H6V4O 10 The specific surface area of ​​MXene is 62.38 m 2 ·g -1 ,H6V4O 10 The specific surface area of ​​MXene-f is only 44.33 m 2 ·g -1 .

[0052] Test Example 2

[0053] The electrochemical performance of the materials prepared in the examples and comparative examples was tested.

[0054] The testing process is:

[0055] PVDF was dissolved in N-methylpyrrolidone (NMP) solution at a concentration of 3%, and stirred for 12 h at room temperature to prepare a uniform solution. 10 / MXene or H6V4O 10 The mixed powder of / MXene-f and acetylene black was added to the solution and stirred for 2 hours to obtain a uniform slurry. The mass ratio of positive electrode material: acetylene black: PVDF is 7:2:1. The slurry was then poured onto a 10μm thick titanium foil and a 20μm thick positive electrode coating was applied using an automatic coating machine. The coated titanium foil was dried at 60°C for 12 hours and cut into discs with a diameter of 12mm. The battery shell used a CR2032 button battery, and the cut electrode sheet was used as the positive electrode, 2mol·L -1 A button cell was assembled with a zinc trifluoromethanesulfonate aqueous solution as the electrolyte, glass fiber as the separator, and a 100 μm thick zinc sheet as the negative electrode.

[0056] Cyclic voltammetry (CV) tests the battery's response current under two conditions: a fixed scan rate and a given voltage range. It also investigates the redox reaction during charge and discharge by analyzing the position changes of the redox peaks in the curve. For hydrated vanadium oxide batteries, the voltage test range is 0.2~1.6V. Figure 5 It can be seen that H6V4O 10 、H6V4O 10 / MXene and H6V4O 10 A total of three samples of / MXene-f were tested in the voltage range of 0.2~1.6V at a speed of 0.5mV•s -1The cyclic voltammetry curves measured at a scanning rate of 100 nm showed two pairs of redox peaks, namely V 3+ / V 4+ and V 4+ / V 5+ , indicating that the introduction of MXene does not affect the H6V4O 10 redox reaction.

[0057] from Figure 6 It can be seen that H6V4O 10 、H6V4O 10 / MXene and H6V4O 10 All aqueous zinc-ion batteries assembled with MXene-f exhibited two charge-discharge plateaus within the voltage ranges of approximately 1.05–1.35 V and 0.4–0.7 V, corresponding to two reversible redox reactions in the CV curves. As the grain size decreases during charge and discharge, the pseudocapacitive behavior becomes dominant over the capacitive behavior, reducing the capacity contribution from the redox process.

[0058] from Figure 7 It can be seen that H6V4O 10 / MXene at 0.1, 0.2, 0.5, 1, 2 and 5 A·g -1 At different current densities, the discharge specific capacities reached 344.7, 311.5, 266.9, 231.7, 197.8, and 150.1 mAh·g, respectively. -1 , showing the best rate performance. 10 It grows on the surface of MXene and forms a bond with MXene, which reduces the dissolution rate of vanadium-based materials. Therefore, when the current density rises, it can still be used at 0.2 A g -1 The current density was maintained at 290.2 mAh g -1 discharge capacity.

[0059] from Figure 8 It can be seen that H6V4O 10 The discharge capacity increased from the initial 235.2 mAh g -1 Gradually decreased to 53.6 mAh g -1 , the capacity retention rate after 2000 cycles is only 22.8%. After MXene composite modification, H6V4O 10 The discharge capacity of MXene increased from the initial 195.0 mAh g -1 Increased to 250.4mAh·g -1 After 2000 charge and discharge cycles, the capacity retention rate reached 50.8%, and the cycle stability was significantly improved.10 In the battery system with MXene-f as the positive electrode, the initial discharge specific capacity is low, only 83.3 mAh g -1 , but after 250 charge and discharge cycles, H6V4O 10 The discharge capacity of MXene-f is increased to 157.1 mAh g -1 , and maintained high cycle stability during the subsequent charge and discharge cycles up to 1000 times, with a capacity retention rate of up to 66.7%. The introduction of MXene can be used as a 10 The growth of the skeleton prevents the vanadium-based material from decreasing the discharge capacity due to structural collapse during the cycle, thereby improving the H6V4O 10 cyclic stability.

[0060] from Figure 9 It can be seen that H6V4O 10 、H6V4O 10 / MXene and H6V4O 10 The arc of the battery assembled with the three materials of / MXene-f is larger in the high frequency area, that is, Zn 2+ There is a large impedance when passing through the SEI film formed on the electrode surface, and compared with H6V4O 10 ,H6V4O 10 / MXene and H6V4O 10 The charge transfer impedance of / MXene-f in the low frequency region is only 79.28 Ω, proving that H6V4O 10 / MXene as a battery positive electrode material is more conducive to charge transport.

[0061] from Figure 10 It can be seen that at a current density of 0.1 A g -1 , under the condition that each charging and relaxation time is 600s, the Zn 2+ The diffusion coefficient was calculated and the results are as follows Figure 10 (b) As shown, D Zn 2+ The range is 10 -9 cm 2 ·s -1 to 10 - 10 cm 2 ·s -1 Compared with H6V4O 10 ,H6V4O 10 The ion diffusion coefficient of / MXene-f is increased by 4 to 5 orders of magnitude, proving that the deintercalation reaction kinetics in the material is relatively fast.

[0062] In summary, H6V4O 10After compounding with Mxene, H6V4O 10 The electrochemical properties of the material are relatively stable.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A H6V4O 10 / A method for preparing a MXene cathode material, characterized in that: The following steps are involved: Vanadium pentoxide and ascorbic acid are dissolved in deionized water to form a mixed solution, and then Mxene is added to the mixed solution to obtain a mixture. The mixture is then subjected to a hydrothermal reaction, and the obtained precipitate is washed and dried to obtain H6V4O 10 / MXene cathode material; The mass ratio of vanadium pentoxide to ascorbic acid is 1:0.8~1.0, and the mass volume ratio of vanadium pentoxide to deionized water is 0.8~1.2g:40mL; Mxene is a multilayer Mxene or a single few-layer Mxene solution; The preparation method of multilayer MXene is: Ti3AlC2 was slowly poured into hydrofluoric acid, stirred and etched with Al in Ti3AlC2, and then repeatedly washed with deionized water until the pH was 6.8-7.

5. After centrifugation and freeze-drying, multilayer MXene powder was obtained; The preparation method of single few-layer MXene solution is as follows: Lithium fluoride is added to hydrochloric acid and stirred in an ice-water bath to obtain a mixed solution. Ti3AlC2 is then slowly poured into the mixed solution, stirred and etched continuously, and then centrifuged and washed until the pH is 4.5-5.

5. The upper layer of the solution is poured out and deionized water is added again. Argon is then introduced as a protective gas and ultrasonicated. Finally, the supernatant is collected by centrifugation to obtain a single-layer MXene solution. The mass volume ratio of multilayer MXene powder and mixed solution is 0.03~0.05g:40mL; The volume ratio of the single few-layer MXene solution and the mixed solution is 5~10:

40.

2. A H6V4O according to claim 1 10 / A method for preparing a MXene cathode material, characterized in that: The temperature of the hydrothermal reaction is 160~200℃, and the time is 20~30h.

3. A H6V4O 10 / MXene cathode material, characterized by: Prepared by the preparation method according to any one of claims 1 to 2.

4. A H6V4O according to claim 3 10 / Application of MXene cathode materials in aqueous zinc-ion batteries.

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