A kind of foamed nickel load (NiO) 0.75 (MnO) 0.25 Porous nanosheet solid solution electrode material and preparation method and application thereof

Abstract

The application discloses a kind of foamed nickel load (NiO) 0.75 (MnO) 0.25 Porous nanosheet solid solution electrode material and its preparation method and application relate to material science and nanotechnology and new energy field, in-situ diffusion and lattice reconstruction of NiO / Mn3O4 heterojunction obtained by microwave-assisted hydrothermal in the process of medium-high temperature heat treatment under certain conditions can induce conversion from uniform arrangement and mutual connection two-dimensional nanosheet array structure to (NiO) 0.75 (MnO) 0.25 Porous nanosheet solid solution effectively increases electrochemical accessible surface area and accelerates charge transfer kinetics, thereby exhibiting high specific capacity, wide voltage window and excellent cycle durability in alkaline aqueous supercapacitors. The method is simple, reproducible, and suitable for large-scale production of high-performance alkaline aqueous supercapacitor electrode materials.

Description

Technical Field

[0001] This invention relates to the fields of materials science, nanotechnology, and new energy, and more specifically, to a nickel foam supported on (NiO). 0.75 (MnO) 0.25 Porous nanosheet solid solution electrode materials, their preparation methods and applications. Background Technology

[0002] Aqueous supercapacitors have attracted widespread attention as promising electrochemical energy storage devices due to their inherent safety, high power density, and excellent cycle durability. However, their widespread application remains severely limited by their inherently low energy density. Therefore, developing simple and effective strategies to overcome this limitation is crucial for realizing high-energy-density aqueous supercapacitors.

[0003] Among numerous electrode candidate materials, non-noble metal transition metal oxides have shown great promise as materials for supercapacitors. In particular, nickel monoxide has attracted widespread attention due to its high theoretical capacitance, cost-effectiveness, and ease of synthesis.

[0004] Heterodoping has been widely recognized as an effective method to improve the electrochemical performance of matrix materials by modulating the electronic structure of the materials and optimizing the charge storage process.

[0005] In general, heterojunctions are difficult to transform into solid solutions; that is, the phase-separated composite interface crystal structure is difficult to transform into a uniform single-phase crystal structure. If heterojunctions can be controllably transformed into solid solutions, it is equivalent to endowing materials with the ability to deform their morphology and switch their functions. This will break the limitations of traditional heterojunction materials and has enormous potential and prospects. Therefore, developing simple and effective strategies to overcome the constraints of heterojunction transformation into solid solutions is crucial. Summary of the Invention

[0006] The purpose of this invention is to overcome the aforementioned deficiencies in the prior art and provide a nickel foam-supported (NiO) solution. 0.75 (MnO) 0.25 Porous nanosheet solid solution electrode materials, their preparation methods, and applications: This method involves in-situ conversion of NiO / Mn3O4 to form (NiO). 0.75 (MnO) 0.25 Porous nanosheet solid solutions are produced using a simple and reproducible process to create nickel-supported foam (NiO). 0.75 (MnO) 0.25 Porous nanosheet solid solution electrode materials can be directly used as electrode materials for alkaline aqueous supercapacitors, exhibiting high specific capacity, wide voltage window and excellent cycle durability, and are suitable for large-scale preparation of high-performance alkaline aqueous supercapacitor electrode materials.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A type of nickel-supported foam (NiO) 0.75 (MnO) 0.25 A method for preparing porous nanosheet solid solution electrode materials includes the following steps:

[0009] S1. NiSO4·7H2O, NaOH, NH4F, CO(NH2)2 and KMnO4 are added to deionized water and mixed to obtain a homogeneous aqueous solution; then the pretreated nickel foam is completely immersed in the homogeneous aqueous solution to obtain a mixture.

[0010] S2. The mixture is transferred to a polytetrafluoroethylene-lined microwave autoclave for microwave-assisted hydrothermal treatment to obtain nickel foam loaded with a precursor; the precursor is a NiO / Mn3O4 heterojunction.

[0011] S3. The nickel foam loaded with the precursor is subjected to medium-to-high temperature heat treatment in a tube furnace to achieve in-situ transformation of NiO / Mn3O4 heterojunction into (NiO). 0.75 (MnO) 0.25 Porous nanosheet solid solution yields nickel foam supported on (NiO). 0.75 (MnO) 0.25 Porous nanosheet solid solution electrode material.

[0012] Optionally, step S1 specifically includes: adding 9.6 mmol to 10 mmol of NiSO4·7H2O, 4.9 mmol of NaOH, 2.5 mmol of NH4F, 4 mmol of CO(NH2)2 and 3 mmol of KMnO4 to 50 mL of deionized water and mixing at room temperature to obtain a homogeneous aqueous solution.

[0013] Optionally, in step S1, the soaking temperature is room temperature.

[0014] Optionally, in step S1, the pretreatment of the nickel foam can employ conventional nickel foam pretreatment methods used in the preparation of electrode materials. For example, the pretreatment steps include: ultrasonically cleaning the nickel foam sequentially with acetone, hydrochloric acid, ethanol, and water, followed by drying. The concentration of the cleaning reagents, the cleaning time, and the order of cleaning can be adjusted according to actual conditions.

[0015] Optionally, in step S2, the microwave power of the microwave-assisted hydrothermal treatment is 800W; the temperature of the microwave-assisted hydrothermal treatment is 140℃~180℃; and the time of the microwave-assisted hydrothermal treatment is 1h~3h.

[0016] Optionally, in step S3, the medium-high temperature heat treatment is performed by heating the temperature to 600℃~700℃ in air at a heating rate of 5℃ / min, followed by medium-high temperature heat treatment for 1h~3h.

[0017] Specifically, the (NiO) 0.75 (MnO) 0.25 The formation of porous nanosheet solid solutions originates from a heterojunction precursor structure constructed under specific microwave-assisted hydrothermal conditions. In this precursor, the face-centered cubic NiO phase (Fm-3m(225), JCPDS No. 89-7130) serves as the main lattice framework. During subsequent specific high-temperature heat treatment, in-situ ion diffusion and lattice reconstruction processes occur, via Mn... 2+ In-situ solid-phase diffusion substitution of Ni in the NiO lattice 2+ The site induces lattice parameter modulation and structural rearrangement, thereby forming a stable (NiO) crystal structure while maintaining its cubic symmetry. 0.75 (MnO) 0.25 Porous nanosheet solid solution lattice system with solid solution phase structure (JCPDS Card No. 78-0425).

[0018] Specifically, the formed (NiO) 0.75 (MnO) 0.25 The porous nanosheet solid solution structure enables the synergistic effect of Ni and Mn elements in the same crystal system. Through electronic structure regulation and local lattice distortion effect, it enhances the density of active sites and charge storage capacity for electrochemical reactions, while maintaining the overall stability of the cubic symmetry crystal structure. This effectively suppresses structural collapse and phase separation, thereby significantly improving the structural stability, electrochemical cycling stability, and tolerance of the electrochemical window while improving specific capacitance / specific capacitance performance.

[0019] Optionally, the NiO / Mn3O4 heterojunction is a two-dimensional nanosheet array structure that is uniformly arranged and interconnected.

[0020] Optionally, the (NiO) 0.75 (MnO) 0.25 The porous nanosheet solid solution is a two-dimensional nanosheet array structure with highly porous and uniformly connected phases.

[0021] Optionally, the (NiO) 0.75 (MnO) 0.25The porous nanosheet solid solution exhibits a coexistence of mesopores and macropores, with the mesopores having a pore size of 2 nm to 50 nm and the macropores having a pore size > 50 nm. This hierarchical pore structure and two-dimensional nanosheet array structure facilitate rapid electrolyte wetting and ion diffusion and migration, shorten the charge transport path, reduce interfacial transport impedance, and significantly increase the effective electrochemical active area, thereby improving the rate performance, energy storage efficiency, and high-rate charge-discharge stability of the electrode material.

[0022] The present invention also discloses a nickel-supported foam (NiO) prepared by the preparation method described above. 0.75 (MnO) 0.25 Porous nanosheet solid solution electrode material.

[0023] The present invention also discloses a nickel-supported foam (NiO) prepared by the preparation method described above. 0.75 (MnO) 0.25 Porous nanosheet solid solution electrode materials, or nickel foam supported (NiO) as described above. 0.75 (MnO) 0.25 Application of porous nanosheet solid solution electrode materials in aqueous supercapacitor electrode materials.

[0024] Optionally, the electrode material of the aqueous supercapacitor is an alkaline aqueous supercapacitor electrode material.

[0025] Optional, nickel foam supported (NiO) 0.75 (MnO) 0.25 Porous nanosheet solid solution electrode materials are used as positive or negative electrode materials for alkaline aqueous supercapacitors.

[0026] Implementing the embodiments of the present invention will have the following beneficial effects:

[0027] The present invention provides a method for preparing nickel-supported foam (NiO). 0.75 (MnO) 0.25 A method for developing porous nanosheet solid solution electrode materials involves using a face-centered cubic nickel oxide lattice as the matrix framework. The NiO / Mn3O4 heterojunction, obtained via a microwave-assisted hydrothermal one-step process, undergoes in-situ diffusion and lattice reconstruction during high-temperature heat treatment under specific conditions, resulting in Ni... 2+ Mn 2+ Partial substitution of the matrix-dopane. This matrix-dopane substitution, while maintaining cubic symmetry, forms a uniform Ni-Mn porous nanosheet solid solution lattice. This induces the transformation from a uniformly arranged and interconnected two-dimensional nanosheet array structure into a highly porous, uniformly arranged and interconnected two-dimensional nanosheet array structure of (NiO). 0.75 (MnO) 0.25Porous nanosheet solid solutions are an effective method to increase the electrochemically accessible surface area and accelerate charge transfer kinetics.

[0028] The nickel-supported foam (NiO) prepared by this invention 0.75 (MnO) 0.25 Porous nanosheet solid solution electrode materials exhibit high specific capacitance, wide voltage window and excellent cycle durability in high-performance alkaline aqueous supercapacitors. Compared with existing technologies, the preparation method of this invention is simple, reproducible and suitable for large-scale preparation of high-performance alkaline aqueous supercapacitor electrode materials. Attached Figure Description

[0029] Figure 1 (NiO) was prepared as described in Example 1 of this invention. 0.75 (MnO) 0.25 XRD pattern of porous nanosheet solid solution supercapacitor electrode material.

[0030] Figure 2 SEM image of the NiO / Mn3O4 heterojunction precursor prepared in Example 1 of this invention.

[0031] Figure 3 The final product (NiO) was prepared for Example 1 of this invention. 0.75 (MnO) 0.25 SEM image of porous nanosheet solid solution supercapacitor electrode material.

[0032] Figure 4 (NiO) was prepared as described in Example 1 of this invention. 0.75 (MnO) 0.25 Porous nanosheet solid solution supercapacitor electrode material in 1Ag -1 The result of constant current charge and discharge is shown in the figure.

[0033] Figure 5 (NiO) was prepared as described in Example 1 of this invention. 0.75 (MnO) 0.25 Figure showing the cycle stability results of porous nanosheet solid solution supercapacitor electrode materials. Detailed Implementation

[0034] The present invention will be further described below with reference to specific embodiments, but this does not limit the present invention in any way.

[0035] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.

[0036] Example 1

[0037] This embodiment features nickel-supported foam (NiO). 0.75(MnO) 0.25 A method for preparing porous nanosheet solid solution electrode materials includes the following steps:

[0038] S1. Add 9.8 mmol of NiSO4·7H2O, 4.9 mmol of NaOH, 2.5 mmol of NH4F, 4 mmol of CO(NH2)2, and 3 mmol of KMnO4 to 50 mL of deionized water and mix at room temperature to obtain a homogeneous aqueous solution. Then, completely immerse the pretreated nickel foam in the homogeneous aqueous solution at room temperature to obtain a mixture.

[0039] S2. The mixture was transferred to a polytetrafluoroethylene-lined microwave autoclave for microwave-assisted hydrothermal treatment. The microwave power was 800W; the temperature of the microwave-assisted hydrothermal treatment was 160℃; and the treatment time was 2 hours, yielding nickel foam loaded with a precursor. The precursor was a NiO / Mn3O4 heterojunction. The mass loading of the NiO / Mn3O4 heterojunction on the nickel foam was 2.3 mg / cm³. 2 .

[0040] S3. The nickel foam loaded with the precursor is placed in a tube furnace and heated to 650°C in air at a heating rate of 5°C / min, and then subjected to medium-high temperature heat treatment for 2 hours to achieve in-situ transformation of NiO / Mn3O4 heterojunction to form (NiO). 0.75 (MnO) 0.25 Porous nanosheet solid solution yields nickel foam supported on (NiO). 0.75 (MnO) 0.25 Porous nanosheet solid solution electrode material.

[0041] Application examples

[0042] The nickel-supported foam (NiO) prepared in Example 1 0.75 (MnO) 0.25 A porous nanosheet solid solution electrode material was directly used as the working electrode, a platinum mesh as the counter electrode, and a saturated calomel electrode as the reference electrode to assemble a three-electrode test system. The electrolyte was 6M KOH, and the electrochemical performance was tested.

[0043] Figure 1 The (NiO) prepared in Example 1 of this invention. 0.75 (MnO) 0.25 XRD pattern of porous nanosheet solid solution supercapacitor electrode material. It can be seen that (NiO) was obtained through this preparation method. 0.75 (MnO) 0.25Solid solution materials with intact phase structures of porous nanosheets. The crystal structures of the heterojunction precursors are high-purity cubic NiO (Fm-3m(225), JCPDS No. 89-7130) and high-purity tetragonal Mn3O4 (I41 / amd(141), JCPDS No. 89-4837). The crystal structure of the product after medium- and high-temperature heat treatment is high-purity cubic phase (NiO). 0.75 (MnO) 0.25 (Fm-3m(225), JCPDS No. 78-0425). It can be known that (NiO) 0.75 (MnO) 0.25 The formation of porous nanosheet solid solutions involves in-situ diffusion and lattice reconstruction of NiO / Mn3O4 heterostructures obtained under microwave-assisted hydrothermal conditions, using a face-centered cubic nickel oxide lattice as the matrix framework. This occurs during medium-to-high temperature heat treatment under specific conditions, resulting in the formation of Ni... 2+ Mn 2+ Partial substitution. This matrix-dopane substitution, while maintaining cubic symmetry, forms a uniform Ni-Mn porous nanosheet solid solution lattice.

[0044] Figure 2 The image shows a SEM image of the NiO / Mn3O4 heterojunction precursor prepared in Example 1 of this invention. As can be seen from the image, the NiO / Mn3O4 heterojunction exhibits a uniformly arranged and interconnected two-dimensional nanosheet array structure.

[0045] Figure 3 The final product (NiO) was prepared for Example 1 of this invention. 0.75 (MnO) 0.25 SEM image of porous nanosheet solid solution; by Figure 3 It can be seen that (NiO) 0.75 (MnO) 0.25 The porous nanosheet solid solution exhibits a highly porous, uniformly arranged, two-dimensional nanosheet array structure. (NiO) 0.75 (MnO) 0.25 Porous nanosheet solid solutions contain abundant mesopores (2nm~50nm) and macropores (>50nm).

[0046] Figure 4 (NiO) was prepared as described in Example 1 of this invention. 0.75 (MnO) 0.25 Porous nanosheet solid solution supercapacitor electrode material in 1Ag -1 The constant current charge-discharge results are shown in the figure, which exhibits a current of 1078.3 C g in an alkaline aqueous supercapacitor. -1 High specific capacity (1 A g) -1), wide voltage window (1.0 V (0–1.0 V vs. Hg / HgO)).

[0047] Figure 5 (NiO) was prepared as described in Example 1 of this invention. 0.75 (MnO) 0.25 Figure showing the cycle stability results of porous nanosheet solid solution supercapacitor electrode materials. Figure 5 (NiO) 0.75 (MnO) 0.25 The electrode exhibits excellent electrochemical stability at 8 A g. - After 6000 cycles under charge and discharge conditions, its initial capacity retention rate is as high as 89.2%.

[0048] Example 2

[0049] This embodiment features nickel-supported foam (NiO). 0.75 (MnO) 0.25 A method for preparing porous nanosheet solid solution electrode materials includes the following steps:

[0050] S1, Same as Example 1.

[0051] S2. The mixture is transferred to a polytetrafluoroethylene-lined microwave autoclave for microwave-assisted hydrothermal treatment. The microwave power is 800W, the temperature of the microwave-assisted hydrothermal treatment is 140℃, and the time of the microwave-assisted hydrothermal treatment is 3h, to obtain nickel foam loaded with the precursor. The precursor is a NiO / Mn3O4 heterojunction.

[0052] S3. The nickel foam loaded with the precursor is placed in a tube furnace and heated to 600°C in air at a heating rate of 5°C / min, and then subjected to medium-high temperature heat treatment for 3 hours to achieve in-situ transformation of NiO / Mn3O4 heterojunction to form (NiO). 0.75 (MnO) 0.25 Porous nanosheet solid solution yields nickel foam supported on (NiO). 0.75 (MnO) 0.25 Porous nanosheet solid solution electrode material.

[0053] Example 3

[0054] This embodiment features nickel-supported foam (NiO). 0.75 (MnO) 0.25 A method for preparing porous nanosheet solid solution electrode materials includes the following steps:

[0055] S1, Same as Example 1.

[0056] S2. The mixture is transferred to a polytetrafluoroethylene-lined microwave autoclave for microwave-assisted hydrothermal treatment. The microwave power is 800W, the temperature of the microwave-assisted hydrothermal treatment is 180℃, and the time of the microwave-assisted hydrothermal treatment is 1h, to obtain nickel foam loaded with the precursor. The precursor is a NiO / Mn3O4 heterojunction.

[0057] S3. Place the nickel foam loaded with the precursor in a tube furnace and heat it to 700°C in air at a heating rate of 5°C / min, then perform medium-high temperature heat treatment for 1 hour to achieve in-situ transformation of NiO / Mn3O4 heterojunction to form (NiO). 0.75 (MnO) 0.25 Porous nanosheet solid solution yields nickel foam supported on (NiO). 0.75 (MnO) 0.25 Porous nanosheet solid solution electrode material.

[0058] The effects of Examples 2 and 3 are the same as those of Example 1.

[0059] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A nickel-supported foam (NiO) 0.75 (MnO) 0.25 The method for preparing porous nanosheet solid solution electrode materials is characterized by, Includes the following steps: S1. NiSO4·7H2O, NaOH, NH4F, CO(NH2)2 and KMnO4 are added to deionized water and mixed to obtain a homogeneous aqueous solution; then the pretreated nickel foam is completely immersed in the homogeneous aqueous solution to obtain a mixture. S2. The mixture is transferred to a polytetrafluoroethylene-lined microwave autoclave for microwave-assisted hydrothermal treatment to obtain nickel foam loaded with a precursor; the precursor is a NiO / Mn3O4 heterojunction. S3. The nickel foam loaded with the precursor is subjected to medium-to-high temperature heat treatment in a tube furnace to achieve in-situ transformation of NiO / Mn3O4 heterojunction into (NiO). 0.75 (MnO) 0.25 Porous nanosheet solid solution yields nickel foam supported on (NiO). 0.75 (MnO) 0.25 Porous nanosheet solid solution electrode materials; In step S2, the microwave power of the microwave-assisted hydrothermal treatment is 800W; the temperature of the microwave-assisted hydrothermal treatment is 140℃~180℃; and the time of the microwave-assisted hydrothermal treatment is 1h~3h. In step S3, the medium-high temperature heat treatment is performed by heating the temperature to 600℃~700℃ in air at a heating rate of 5℃ / min for 1h~3h. The NiO / Mn3O4 heterojunction is a two-dimensional nanosheet array structure that is uniformly arranged and interconnected. The (NiO) 0.75 (MnO) 0.25 The porous nanosheet solid solution is a highly porous, homogeneous, two-dimensional nanosheet array structure. The (NiO) 0.75 (MnO) 0.25 The porous nanosheet solid solution has mesopores and macropores, wherein the pore size of the mesopores is 2nm~50nm and the pore size of the macropores is >50nm; (NiO) 0.75 (MnO) 0.25 The formation of porous nanosheet solid solutions involves in-situ diffusion and lattice reconstruction of NiO / Mn3O4 heterostructures obtained under microwave-assisted hydrothermal treatment, using a face-centered cubic nickel oxide lattice as the matrix framework. This process, along with the high-temperature heat treatment, leads to the formation of Ni... 2+ Mn 2+ Partial substitution; this matrix-dopane substitution, while maintaining cubic symmetry, forms a uniform Ni-Mn porous nanosheet solid solution lattice.

2. The nickel-supported foam (NiO) according to claim 1 0.75 (MnO) 0.25 The method for preparing porous nanosheet solid solution electrode materials is characterized by, Step S1 specifically includes: adding 9.6 mmol to 10 mmol of NiSO4·7H2O, 4.9 mmol of NaOH, 2.5 mmol of NH4F, 4 mmol of CO(NH2)2 and 3 mmol of KMnO4 to 50 mL of deionized water and mixing at room temperature to obtain a homogeneous aqueous solution.

3. A nickel-supported foam (NiO) prepared by the preparation method according to any one of claims 1-2. 0.75 (MnO) 0.25 Porous nanosheet solid solution electrode material.

4. A nickel-supported foam (NiO) prepared by the preparation method according to any one of claims 1-2. 0.75 (MnO) 0.25 Application of porous nanosheet solid solution electrode materials in aqueous supercapacitor electrode materials.

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