Porous aggregate Ni-Mn5O8-coated Na2Mn8O16 composite material and preparation method thereof

Abstract

The invention discloses a porous aggregate Ni-Mn5O8-coated Na2Mn8O16 composite material and a preparation method thereof, and belongs to the field of inorganic materials. The preparation method comprises the following steps: dissolving nickel nitrate hexahydrate, a manganous nitrate solution, urea and sodium bicarbonate in purified water, and carrying out constant-temperature reaction in a hydrothermal reaction kettle; and filtering after the reaction is finished, drying the product in a drying oven, calcining in a muffle furnace, and cooling to obtain the Ni-Mn5O8-coated Na2Mn8O16 composite material. According to the method, the electrochemical performance of the composite material is improved by optimizing the ratio of raw materials, a porous aggregate is observed microcosmically, the structure is beneficial to full permeation of an electrolyte and rapid transmission of ions, nucleation energy barriers of Zn < 2 + > on an electrode / electrolyte interface are reduced, the reversible deposition-dissolution behavior of zinc ions is promoted, and the electrochemical performance of the composite material is improved. And the rate capability of the water-based zinc ion battery is further improved.

Description

Technical Field

[0001] This invention discloses porous aggregates Ni-Mn5O8@Na2Mn8O 16 The composite material and its preparation method belong to the field of aqueous zinc-ion battery technology in inorganic materials. Background Technology

[0002] The increasingly severe environmental problems and global energy crisis urgently necessitate the development of next-generation energy storage technologies and an increase in the proportion of renewable energy, which has become a key path to achieving the goals of "carbon peaking" and "carbon neutrality." Against this backdrop, aqueous zinc-ion batteries have attracted widespread attention due to their inherent safety, high theoretical specific capacity, and the natural abundance of zinc resources. Therefore, the development of rechargeable aqueous zinc-ion batteries is of great significance. Currently, the development of aqueous zinc-ion batteries is mainly limited by the performance bottleneck of cathode materials, making the research of high-performance cathode materials crucial. Aqueous zinc-ion battery cathode materials exhibit problems such as poor structural stability and slow reaction kinetics in practical applications, directly affecting the improvement of overall battery performance. Only by solving this problem can the large-scale application of aqueous zinc-ion batteries be realized, enabling them to stand out in the highly competitive energy storage market.

[0003] Manganese oxides show great promise as cathode materials for aqueous zinc-ion batteries. They possess advantages such as high redox capability, low cost, and good electrochemical performance. However, due to low conductivity and easy solubility, the cycle stability and rate performance of transition metal manganese oxides as battery cathode materials are not ideal, limiting their practical application. To address these issues, compounding manganese oxides is currently the most effective method. Compounding involves optimizing combinations with other oxides, which not only shortens the diffusion distance of ions within the active material but also increases the depth of electrochemical reactions. This effectively suppresses problems such as volume expansion and dissolution in the active material and improves the material's electronic conductivity. Summary of the Invention

[0004] To overcome the above-mentioned technical defects, the present invention provides porous aggregates Ni-Mn5O8@Na2Mn8O 16 The composite material and its preparation method are disclosed. In the preparation of this material, nickel nitrate hexahydrate, manganese nitrate solution, urea, and sodium bicarbonate are added sequentially to pure water and stirred until homogeneous. After thorough mixing, the mixture is placed in a hydrothermal reactor and reacted at a constant temperature in an oven. After the reaction is complete, the reaction product is removed, washed, dried at a constant temperature, and then calcined in a muffle furnace at a constant temperature. The material is obtained after cooling in the furnace. This synthesis method is simple, low-cost, and suitable for large-scale industrial production.

[0005] The porous aggregate Ni-Mn5O8@Na2Mn8O of the present invention 16The composite material exhibits XRD diffraction peaks at 18.1°, 28.7°, 37.5°, and 66.15°; XPS peaks at 1070.75 eV, 641.39 eV, 653.10 eV, 854.43 eV, 848.93 eV, 872.1 eV, 530.67 eV, and 529.01 eV, with Mn exhibiting coexistence of +2, +3, and +4 valences.

[0006] This invention also provides porous aggregates Ni-Mn5O8@Na2Mn8O 16 The method for preparing composite materials includes the following steps:

[0007] The first step is to disperse nickel nitrate hexahydrate and manganese nitrate in deionized water, then add urea and sodium bicarbonate in sequence and stir until well mixed.

[0008] The second step is to place the mixed solution in a hydrothermal reactor, react it at a constant temperature in an oven, and then allow it to cool down naturally.

[0009] The third step is to remove the product from the hydrothermal reactor, clean and filter it, and then put it into an oven to dry.

[0010] The fourth step is to calcine the material in a muffle furnace and then cool it to obtain porous aggregates Ni-Mn5O8@Na2Mn8O. 16 Composite materials.

[0011] Furthermore, in the above technical solution, in the first step, the molar ratio of nickel nitrate hexahydrate to manganese nitrate is 1:8; the molar ratio of urea to sodium bicarbonate is 5:7.

[0012] Furthermore, in the above technical solution, in the first step, the molar ratio of nickel nitrate hexahydrate, urea, and sodium bicarbonate is 1:10:14.

[0013] Furthermore, in the above technical solution, in the second step, the constant temperature reaction temperature is 160℃ and the reaction time is 8 hours.

[0014] Furthermore, in the above technical solution, in the third step, the reaction product is cleaned with pure water. The reaction product is placed in pure water to form a suspension, and then ultrasonically cleaned for 3 minutes in an ultrasonic cleaner. The suspension is then filtered, and the product is cleaned a total of 3 times.

[0015] Furthermore, in the above technical solution, in the third step, the drying temperature is 80℃ and the drying time is 1 hour.

[0016] Furthermore, in the above technical solution, in the fourth step, the calcination temperature is 450℃, and the constant temperature calcination time is 5 hours, of which the heating program is set for 2 hours and the cooling to below 200℃ for 2 hours.

[0017] The present invention also provides the above-mentioned porous aggregate Ni-Mn5O8@Na2Mn8O 16 Application of composite materials in aqueous zinc-ion batteries.

[0018] Beneficial effects of the invention:

[0019] 1. This invention prepares porous aggregates Ni-Mn5O8@Na2Mn8O 16 Composite materials use inexpensive and readily available raw materials, have simple synthesis methods, and are relatively environmentally friendly in their preparation process, resulting in less environmental pollution.

[0020] 2. This method optimizes Ni-Mn5O8@Na2Mn8O 16 The electrochemical properties of the composite material were observed at the microscopic level to exhibit a porous aggregate morphology. This structure facilitates the full penetration of the electrolyte and rapid ion transport, reduces the activation energy of ion diffusion, and helps to reduce Zn content. 2+ The nucleation energy barrier at the electrode / electrolyte interface promotes the reversible deposition-dissolution behavior of zinc ions, thereby improving the rate performance of aqueous zinc-ion batteries. Attached Figure Description

[0021] Figure 1 The Ni-Mn5O8@Na2Mn8O in Example 1 16 XRD pattern of composite material;

[0022] Figure 2 The Ni-Mn5O8@Na2Mn8O in Example 1 16 SEM image of composite material;

[0023] Figure 3 The Ni-Mn5O8@Na2Mn8O in Example 1 16 XPS plot of composite material;

[0024] Figure 4 The Ni-Mn5O8@Na2Mn8O in Example 1 16 EDS diagram of composite materials;

[0025] Figure 5 The Ni-Mn5O8@Na2Mn8O in Example 1 16 Elemental distribution diagram of composite materials;

[0026] Where: a is the distribution map of Na element, b is the distribution map of Mn element, c is the distribution map of O element, and d is the distribution map of Ni element;

[0027] Figure 6 The Ni-Mn5O8@Na2Mn8O in Example 1 16 Infrared spectrum of composite material;

[0028] Figure 7 The Ni-Mn5O8@Na2Mn8O in Example 1 16 Raman spectra of composite materials;

[0029] Figure 8 The Ni-Mn5O8@Na2Mn8O in Example 5 16 Composite material cyclic charge-discharge diagram;

[0030] Figure 9 The Ni-Mn5O8@Na2Mn8O in Example 5 16 Cyclic voltammetry of composite materials;

[0031] Figure 10 The Ni-Mn5O8@Na2Mn8O in Example 5 16 AC impedance diagram of composite materials. Detailed Implementation

[0032] The present invention is further described below through specific examples. However, these examples are merely exemplary and are not limited to the scope of protection of the present invention; they are merely embodiments.

[0033] In the following embodiments, unless otherwise specified, the reagents, materials and instruments used are all conventional reagents, materials and instruments, and are commercially available. The reagents involved can also be synthesized by conventional synthesis methods.

[0034] Example 1

[0035] The first step is to weigh 0.8724g of nickel nitrate hexahydrate and 8.5896g of 50% manganese nitrate solution and stir them.

[0036] The second step is to add 1.8018g of urea and 3.5284g of sodium bicarbonate to the well-mixed solution and stir for 1 hour.

[0037] The third step involves continuously stirring the above mixed solution for 1 hour and then placing it in a hydrothermal reactor. The mixture is then kept at a constant temperature of 160°C in an oven for 8 hours, followed by natural cooling.

[0038] The fourth step is to remove the reaction product from the hydrothermal reactor and perform a cleaning operation. Use pure water to clean and filter the reaction product, place the reaction product in pure water to form a suspension, and sonicate it in an ultrasonic cleaner for 3 minutes. Then filter the suspension. The process is repeated a total of 3 times.

[0039] Fifth step: Place the cleaned and filtered product into an oven and dry at 80°C for 1 hour.

[0040] The sixth step involves calcining the dried product in a muffle furnace. After calcination, the product is cooled in the furnace to obtain Ni-Mn5O8@Na2Mn8O. 16 Composite material. The calcination temperature is 450℃, with the heating program set for 2 hours, cooling to below 200℃ for 2 hours, and the constant temperature calcination time for 5 hours.

[0041] Figure 1 Ni-Mn5O8@Na2Mn8O was demonstrated 16 XRD pattern of the composite material. Positions of the main diffraction peaks are related to Mn5O8 (standard card PDF#00-029-1244) and Na2Mn8O. 16 (Standard card PDF#00-039-1218) The standard spectra match well, indicating that the composite material is mainly composed of Mn5O8 and Na2Mn8O 16 The composition is two-phase. By performing full-spectrum fitting on the XRD patterns, the mass fractions of each phase were determined to be 53.2% Mn5O8 and 53.2% Na2Mn8O. 16 46.8%. Among them, the Mn5O8 phase belongs to the monoclinic crystal system (space group C2 / m), and its characteristic diffraction peaks are located at 18.1° and 66.15°, corresponding to the (200) and (223) crystal planes, respectively. Na2Mn8O 16 The phase belongs to the tetragonal crystal system (space group I4 / m), and it exhibits strong diffraction peaks at 28.7° and 37.5°, which belong to the (310) and (211) crystal planes, respectively.

[0042] Figure 2 for Ni-Mn5O8@Na2Mn8O 16 SEM images of the composite material clearly show the porous aggregate morphology. This structure facilitates the full penetration of the electrolyte and the rapid transport of ions, which helps to reduce Zn content. 2+ The nucleation energy barrier at the electrode / electrolyte interface promotes the reversible deposition-dissolution behavior of zinc ions, thereby improving the rate performance of aqueous zinc-ion batteries.

[0043] Figure 3 for Ni-Mn5O8@Na2Mn8O 16 XPS full spectrum of the composite material. Characteristic peaks for Na 1s, Mn 2p, O 1s, and Ni 2p can be observed in the image. The Na 1s characteristic peak is located at a binding energy of 1070.75 eV, and the O 1s characteristic peaks are located at 530.67 eV and 529.01 eV. The Mn 2p3 / 2 peak is located at 641.39 eV, and the Mn 2p1 / 2 peak is located at 653.10 eV. Further peak splitting of Mn2p3 / 2 reveals three peaks with binding energies of 640.49 eV, 641.49 eV, and 642.94 eV, corresponding to Mn 1s, Mn 2p, and Ni 2p, respectively.2+ Mn 3+ and Mn 4+ Species. Ni2p1 / 2 is located at 872.1 eV, and Ni2p3 / 2 splits into two peaks at 854.43 eV, confirming that Ni... 3+ It exists, and the peak at 848.93 eV corresponds to Ni. 2+ .

[0044] Figure 4 for Ni-Mn5O8@Na2Mn8O 16 The EDS plot of the composite material showed characteristic peaks of Mn, O, Na and Ni in the selected analysis regions, confirming that nickel has been successfully introduced into the composite material system.

[0045] Figure 5 for Ni-Mn5O8@Na2Mn8O 16 The elemental distribution diagram of the composite material shows that O has the highest signal intensity and the most uniform spatial distribution, covering all analyzed areas. Mn has the second highest signal intensity, and its spatial distribution highly overlaps with that of O, consistent with the characteristics of composite oxides. In contrast, Na is more dispersed in the porous aggregates. Ni has a relatively low signal intensity, exhibiting a discrete point distribution, and is mainly enriched in the particle surface area.

[0046] Figure 6 for Ni-Mn5O8@Na2Mn8O 16 Composite materials in 400-4000cm -1 FTIR spectra within the range. Characteristic absorption peaks associated with metal-oxygen bonding were observed in the low-frequency region, with one peak located at 437.84 cm⁻¹. -1 Peak belongs to Mn 2+ -O bond stretching vibration, 526.6cm -1 The peak corresponds to Mn in octahedral coordination [MnO6]. 3+ -O bond stretching vibration, 580.57cm -1 The peak corresponds to Mn in the [MnO6] octahedron. 4+ -O bond stretching vibration. Additionally, 399.2 cm -1 The vibration peak can be attributed to the stretching vibration of the Na-O bond.

[0047] Figure 7 for Ni-Mn5O8@Na2Mn8O 16 Raman spectra of composite materials, with 610–662 cm⁻¹ -1 The broad peaks within this range correspond to the symmetric stretching vibrations of the Mn-O bonds in the Mn-O-Mn groups, reflecting the vibrational characteristics of the manganese-oxygen octahedral framework. (318.1 cm⁻¹) -1 The peak can be attributed to Mn 3+-O bond-related bending / stretching vibration mode, 537.9cm -1 The peak corresponds to Mn in the [MnO6] octahedron. 4+ -O bond-related bending / stretching vibration modes. And located at 368cm... -1 The Raman peaks are mainly attributed to lattice vibration modes involving Na-O bond motion.

[0048] Example 2

[0049] The first step is to weigh 0.8724g of nickel nitrate hexahydrate and 8.5896g of 50% manganese nitrate solution and stir them.

[0050] The second step is to add 2.8829g of urea and 2.0162g of sodium bicarbonate to the well-mixed solution and stir for 1 hour.

[0051] The third step involves continuously stirring the above mixed solution for 1 hour and then placing it in a hydrothermal reactor. The mixture is then kept at a constant temperature of 160°C in an oven for 8 hours, followed by natural cooling.

[0052] The fourth step is to remove the reaction product from the hydrothermal reactor and perform a cleaning operation. Use pure water to clean and filter the reaction product, place the reaction product in pure water to form a suspension, and sonicate it in an ultrasonic cleaner for 3 minutes. Then filter the suspension. The process is repeated a total of 3 times.

[0053] Fifth step: Place the cleaned and filtered product into an oven and dry at 80°C for 1 hour.

[0054] The sixth step involves calcining the dried product in a muffle furnace. After calcination, the product is cooled in the furnace to obtain Ni-Mn5O8@Na2Mn8O. 16 Composite material. The calcination temperature is 450℃, with the heating program set for 2 hours, cooling to below 200℃ for 2 hours, and the constant temperature calcination time for 5 hours.

[0055] Example 3

[0056] The first step is to weigh 0.8724g of nickel nitrate hexahydrate and 8.5896g of 50% manganese nitrate solution and stir them.

[0057] The second step is to add 2.5225g of urea and 2.5203g of sodium bicarbonate to the well-mixed solution and stir for 1 hour.

[0058] The third step involves continuously stirring the above mixed solution for 1 hour and then placing it in a hydrothermal reactor. The mixture is then kept at a constant temperature of 160°C in an oven for 8 hours, followed by natural cooling.

[0059] The fourth step is to remove the reaction product from the hydrothermal reactor and perform a cleaning operation. Use pure water to clean and filter the reaction product, place the reaction product in pure water to form a suspension, and sonicate it in an ultrasonic cleaner for 3 minutes. Then filter the suspension. The process is repeated a total of 3 times.

[0060] Fifth step: Place the cleaned and filtered product into an oven and dry at 80°C for 1 hour.

[0061] The sixth step involves calcining the dried product in a muffle furnace. After calcination, the product is cooled in the furnace to obtain Ni-Mn5O8@Na2Mn8O. 16 Composite material. The calcination temperature is 450℃, with the heating program set for 2 hours, cooling to below 200℃ for 2 hours, and the constant temperature calcination time for 5 hours.

[0062] Example 4

[0063] The first step is to weigh 0.8724g of nickel nitrate hexahydrate and 8.5896g of 50% manganese nitrate solution and stir them.

[0064] The second step is to add 1.4414g of urea and 4.0325g of sodium bicarbonate to the well-mixed solution and stir for 1 hour.

[0065] The third step involves continuously stirring the above mixed solution for 1 hour and then placing it in a hydrothermal reactor. The mixture is then kept at a constant temperature of 160°C in an oven for 8 hours, followed by natural cooling.

[0066] The fourth step is to remove the reaction product from the hydrothermal reactor and perform a cleaning operation. Use pure water to clean and filter the reaction product, place the reaction product in pure water to form a suspension, and sonicate it in an ultrasonic cleaner for 3 minutes. Then filter the suspension. The process is repeated a total of 3 times.

[0067] Fifth step: Place the cleaned and filtered product into an oven and dry at 80°C for 1 hour.

[0068] The sixth step involves calcining the dried product in a muffle furnace. After calcination, the product is cooled in the furnace to obtain Ni-Mn5O8@Na2Mn8O. 16 Composite material. The calcination temperature is 450℃, with the heating program set for 2 hours, cooling to below 200℃ for 2 hours, and the constant temperature calcination time for 5 hours.

[0069] Example 5

[0070] The Ni-Mn5O8@Na2Mn8O prepared in Examples 1-4 16 Composite materials were used to prepare the positive electrode for aqueous zinc-ion batteries.

[0071] The first step is to weigh out Ni-Mn5O8@Na2Mn8O 16 0.24g of the composite material and 0.03g of acetylene black were thoroughly ground using an agate mortar.

[0072] The second step involves adding a binder made from a mixture of 0.03g polyvinylidene fluoride and 0.6mL N-methylpyrrolidone to the ground product.

[0073] The third step is to coat the mixed slurry onto a 0.01mm thick stainless steel foil and dry it at a constant temperature of 80℃ for 1 hour.

[0074] The fourth step is to process the stainless steel foil into a positive electrode sheet with a diameter of 10mm after the active material is completely dried.

[0075] The fifth step involves assembling an aqueous zinc-ion battery using a zinc sheet as the negative electrode, glass fiber paper as the separator, and a mixture of 2 mol / L ZnSO4 and 0.2 mol / L MnSO4 solutions as the electrolyte. The battery is then left to stand for 24 hours before testing.

[0076] Figure 8 With Ni-Mn5O8@Na2Mn8O 16 The composite material serves as the positive electrode for a water-based zinc-ion battery, showing its cyclic charge-discharge characteristics. The charge-discharge test currents were set at 50 mA / g, 100 mA / g, 200 mA / g, 300 mA / g, and 500 mA / g. The Ni-Mn5O8@Na2Mn8O4 composite material prepared in Example 1... 16 The composite material exhibits a maximum initial discharge capacity of 334.41 mAh g at a low current density of 50 mA / g. -1 .

[0077] Figure 9 With Ni-Mn5O8@Na2Mn8O 16 Cyclic voltammogram of an aqueous zinc-ion battery with a composite material as the positive electrode. The graph shows that with increasing urea content, the largest CV peak area is observed, reflecting a higher reversible capacity. However, the redox peak potential difference is also relatively large, suggesting a potentially stronger polarization phenomenon.

[0078] Figure 10 With Ni-Mn5O8@Na2Mn8O 16 The AC impedance curve of an aqueous zinc-ion battery with composite material as the positive electrode shows that as the amount of urea decreases, the charge transfer impedance gradually increases, and the resistance during the insertion and extraction of zinc ions also increases.

[0079] Based on the disclosure in the foregoing specification, those skilled in the art can make appropriate changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention.

Claims

1. Porous aggregates Ni-Mn5O8@Na2Mn8O 16 Composite material, characterized in that: XRD diffraction peaks are at 18.1°, 28.7°, 37.5°, and 66.15°; XPS peaks are at 1070.75 eV, 641.39 eV, 653.10 eV, 854.43 eV, 848.93 eV, 872.1 eV, 530.67 eV, and 529.01 eV, with Mn exhibiting coexistence of +2, +3, and +4 valences.

2. The porous aggregate Ni-Mn5O8@Na2Mn8O as described in claim 1 16 A method for preparing composite materials, characterized in that, Includes the following steps: The first step is to disperse nickel nitrate hexahydrate and manganese nitrate in deionized water, then add urea and sodium bicarbonate in sequence and stir until well mixed. The second step is to place the well-stirred solution into a hydrothermal reactor, react it at a constant temperature in an oven, and then allow it to cool naturally. The third step is to remove the product from the hydrothermal reactor, wash and filter it, and then put it into an oven to dry. The fourth step involves calcination in a muffle furnace followed by cooling to obtain porous aggregates Ni-Mn5O8@Na2Mn8O. 16 Composite materials.

3. The porous aggregate Ni-Mn5O8@Na2Mn8O according to claim 2 16 A method for preparing composite materials, characterized in that: In the first step, the molar ratio of nickel nitrate hexahydrate to manganese nitrate is 1:8; the molar ratio of urea to sodium bicarbonate is 5:

7.

4. The porous aggregate Ni-Mn5O8@Na2Mn8O according to claim 3 16 A method for preparing composite materials, characterized in that: In the first step, the molar ratio of nickel nitrate hexahydrate, urea, and sodium bicarbonate is 1:10:

14.

5. The porous aggregate Ni-Mn5O8@Na2Mn8O according to claim 2 16 A method for preparing composite materials, characterized in that: In the second step, the constant temperature reaction temperature is 160℃, and the reaction time is 8 hours.

6. The porous aggregate Ni-Mn5O8@Na2Mn8O according to claim 2 16 A method for preparing composite materials, characterized in that: In the third step, the reaction product is washed with pure water. The reaction product is placed in pure water to form a suspension, and then ultrasonicated for 3 minutes in an ultrasonic cleaner. The suspension is then filtered. The washing is repeated a total of 3 times.

7. The porous aggregate Ni-Mn5O8@Na2Mn8O according to claim 2 16 A method for preparing composite materials, characterized in that: In the third step, the drying temperature is 80℃ and the drying time is 1 hour.

8. The porous aggregate Ni-Mn5O8@Na2Mn8O according to claim 2 16 A method for preparing composite materials, characterized in that: In the fourth step, the calcination temperature is 450℃ and the constant temperature calcination time is 5 hours, of which: the heating program is set for 2 hours and the cooling to below 200℃ takes 2 hours.

9. The porous aggregate Ni-Mn5O8@Na2Mn8O as described in claim 1 16 Application of composite materials in aqueous zinc-ion batteries.

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