A type of MnO2 / (NiO) 0.5 (MnO) 0.5 Composite materials, their preparation methods and applications

Abstract

This invention discloses a MnO2 / (NiO) method. 0.5 (MnO) 0.5 The composite material, its preparation method, and its application are disclosed. The method includes: Step 1: Weighing 0.1–0.5 mmol MnSO4·H2O and 1–2.5 mmol KMnO4, adding them to 10–25 mL of deionized water, and magnetically stirring to obtain a purple-red transparent solution. Then, adding 0.06–0.3 mmol NiCl2·6H2O to the solution and continuing stirring to obtain mixed solution A; Step 2: Transferring mixed solution A to a high-pressure reactor, sealing it, and placing it in a constant-temperature oven. The temperature is increased from room temperature to 150–200°C at a heating rate of 5°C / min, and the hydrothermal reaction is carried out for 12–36 h. After natural cooling to room temperature, the solution is washed and vacuum dried sequentially to obtain precursor B; Step 3: Placing precursor B in a tube furnace and calcining it in air at a heating rate of 5°C / min from room temperature to 250–400°C for 2–6 h to obtain MnO2 / (NiO). 0.5 (MnO) 0.5 Composite materials. This invention significantly suppresses the Jahn-Teller effect and Mn through the strong electronic coupling effect between the two phases. 3+ The disproportionation dissolution improves the structural stability and conductivity of the material.

Description

Technical Field

[0001] This invention relates to a cathode material for aqueous zinc-ion batteries, specifically a MnO2 / (NiO) compound. 0.5 (MnO) 0.5 Composite materials, their preparation methods, and applications. Background Technology

[0002] With the overexploitation and rapid consumption of fossil fuels, energy issues and environmental degradation have become a major concern. Developing clean, inexpensive, and environmentally friendly energy storage devices to alleviate the current energy crisis is of great significance for national economic development and achieving sustainable development. Aqueous zinc-ion batteries (AZIBs) are particularly advantageous due to their intrinsic safety, low cost, environmental friendliness, and the high theoretical capacity (approximately 820 mAh·g) of their zinc metal anode. - ¹) and with a suitable redox potential (-0.76 V vsSHE), it is considered one of the most promising energy storage systems.

[0003] Among numerous cathode materials, MnO2 has become a research hotspot for AZIBs cathode materials due to its high theoretical capacity, abundant resources, low toxicity, and clear discharge plateau. The basic structural unit of MnO2 is the [MnO6] octahedron, which can form various crystal forms through edge-sharing or corner-sharing connections. Among them, α-MnO2, due to its open tunnel structure and good structural stability, is beneficial to Zn 2+ Rapid and reversible insertion / extraction. However, MnO2-based materials face significant challenges in practical applications: during charge and discharge processes, Mn... 3+ The Jahn-Teller effect leads to asymmetric distortion of the [MnO6] octahedron, causing lattice stress accumulation and structural collapse; simultaneously, Mn 3+ It readily undergoes a disproportionation reaction, generating Mn. 2+ It dissolves in the electrolyte, causing a sharp decline in capacity; these problems severely restrict the commercial application of MnO2 cathode materials.

[0004] To overcome these shortcomings, researchers have proposed strategies such as element doping, surface coating, and heterostructure construction. Among these, element doping (such as N, P, Zn, Mg, etc.) can regulate the local electronic structure of MnO2 and stabilize the lattice; surface coating with carbon or conductive polymer layers can physically suppress manganese dissolution; and heterostructure construction can enhance interfacial charge transfer. However, these strategies often have inherent drawbacks, such as inactive dopants reducing capacity, coating layers hindering ion transport, or a lack of understanding of the mechanism for regulating the electronic structure of heterostructure interfaces.

[0005] Therefore, there is an urgent need for a rational design strategy that can simultaneously address the issues of structural stability, electronic conductivity, and reaction kinetics. Summary of the Invention

[0006] The purpose of this invention is to provide a MnO2 / (NiO) 0.5 (MnO) 0.5 Composite materials, their preparation methods, and applications demonstrate how strong electronic coupling between two phases can significantly suppress the Jahn-Teller effect and MnO2. 3+ The disproportionation dissolution improves the structural stability and conductivity of the material, giving aqueous zinc-ion batteries excellent rate performance and long-term cycle stability.

[0007] This invention is achieved through the following technical solution: A type of MnO2 / (NiO) 0.5 (MnO) 0.5 The preparation method of the composite material includes the following steps: Step 1: Weigh 0.1~0.5 mmol MnSO4·H2O and 1~2.5 mmol KMnO4, add them to 10~25 mL of deionized water, stir magnetically to obtain a purple-red transparent solution, then add 0.06~0.3 mmol NiCl2·6H2O to it, continue stirring to obtain mixed solution A; Step 2: Transfer the mixed solution A to a high-pressure reactor, seal it, place it in a constant temperature oven, and heat it from room temperature to 150~200℃ at a heating rate of 5℃ / min. Perform the hydrothermal reaction for 12~36 h, cool it naturally to room temperature, and wash and vacuum dry it in sequence to obtain precursor B. Step 3: Place precursor B in a tube furnace and calcine it at a heating rate of 5℃ / min from room temperature to 250~400℃ for 2~6 h in an air atmosphere to obtain MnO2 / (NiO). 0.5 (MnO) 0.5 Composite materials.

[0008] Furthermore, the atomic numbers of Mn and Ni in the mixed solution A of step 1 meet the condition that the atomic number of Ni accounts for 5% to 21.4% of the total atomic number of Mn and Ni.

[0009] Furthermore, in step 1, the amounts of MnSO4·H2O, KMnO4, deionized water, and NiCl2·6H2O are 0.3 mmol, 1.7 mmol, 15 mL, and 0.15 mmol, respectively.

[0010] Furthermore, the magnetic stirring in step 1 is performed using a magnetic stirrer at a speed of 500 rpm for 10 minutes; the stirring is continued at a speed of 600 rpm for 30 minutes.

[0011] Furthermore, the hydrothermal reaction in step 2 is carried out at a heating rate of 5°C / min, with the temperature increased from room temperature to 180°C, and the hydrothermal reaction is carried out for 24 hours.

[0012] Furthermore, the washing in step 2 involves washing three times each with deionized water and anhydrous ethanol.

[0013] Furthermore, the vacuum drying in step 2 is carried out at 50~70℃ for 10~14 h.

[0014] Furthermore, the calcination in step 3 is carried out in an air atmosphere, with the temperature increased from room temperature to 300°C at a heating rate of 5°C / min, and calcined for 4 hours.

[0015] A type of MnO2 / (NiO) 0.5 (MnO) 0.5 In the composite material, Ni is incorporated into the MnO2 lattice in the form of dopant, thereby allowing nanosheet-like (NiO) to be grown in situ within the MnO2 matrix. 0.5 (MnO) 0.5 Phase, (NiO) 0.5 (MnO) 0.5 The phase forms an atomically close heterogeneous interface with the nanorod-shaped α-crystalline MnO2.

[0016] A type of MnO2 / (NiO) 0.5 (MnO) 0.5 Application of composite materials as cathode materials in aqueous zinc-ion batteries.

[0017] The present invention has the following beneficial technical effects: 1) This invention combines a one-step hydrothermal bonding and calcination process to successfully grow (NiO) in situ in a MnO2 matrix. 0.5 (MnO) 0.5 The composite phase constructs a MnO2 / (NiO) structure with an atomically close contact interface. 0.5 (MnO) 0.5Compared with traditional non-in-situ physical mixing or stepwise synthesis methods, the in-situ growth strategy of this invention has the following outstanding advantages: First, the two phases form a continuous and seamless heterojunction interface through chemical bonding, avoiding common interface defects, lattice mismatch, and poor contact problems in non-in-situ composites, thereby achieving efficient charge transfer at the interface; Second, the composite phase is uniformly distributed inside the MnO2 matrix, forming a three-dimensional interpenetrating network structure, which not only improves the conductivity of the overall electrode as an "electron highway" but also buffers the volume expansion / contraction stress during charging and discharging as a "structural pillar," giving the material good structural stability; Third, in-situ growth avoids additional binders and conductive additives, simplifies the electrode preparation process, and improves the loading and utilization rate of active materials. 2) This invention introduces (NiO) 0.5 (MnO) 0.5 The composite phase effectively suppresses Mn during discharge at the electronic structure level. 3+ The Jahn-Teller distortion fundamentally solves the structural stability problem of MnO2-based cathode materials. Theoretical calculations (DFT) show that the Structural Stability of MnO2 and (NiO) is significantly improved. 0.5 (MnO) 0.5 At the heterojunction interface, significant charge redistribution and bandgap modulation occurred. Specifically, firstly, interface interactions induced the 3d orbitals (ε) of Mn. d ) and O 2p orbitals (ε p The band shifts simultaneously toward the Fermi level, while reducing the dp band center difference (Δ). d-p This indicates that the hybridization of Mn-d and Op orbitals is significantly enhanced; secondly, the stronger dp hybridization increases the covalent nature of Mn-O bonds in the [MnO6] octahedron, thereby suppressing Mn... 3+ Because of e g The octahedral distortion tendency caused by electron asymmetry occupation; thirdly, the suppression of lattice distortion further reduces the accumulation of local stress during cycling, effectively preventing the periodic collapse of the tunnel structure; therefore, the composite material prepared by this invention exhibits excellent structural reversibility during long cycling. 3) In the material of this invention (NiO) 0.5 (MnO) 0.5 The presence of the composite phase inhibits Mn at both physical and chemical levels. 3+ The disproportionation dissolution significantly improves the utilization rate and cycle life of active materials, which is attributed to: on the one hand, (NiO) 0.5 (MnO) 0.5 The phase acts as a stable protective layer, physically preventing the electrolyte from interacting with the active Mn on the MnO2 surface. 3+ Direct contact with Mn reduces2+ The dissolution of Ni in the composite phase; on the other hand, the dissolution of Ni in the composite phase. 2+ Ions can modulate the local pH and coordination environment at the interface, reducing Mn 3+ Thermodynamic driving force of disproportionation reaction; 4) The preparation method of this invention is simple, low-cost, and highly controllable. By adjusting the amount of Ni doping, the ratio of the composite phase and the interface structure can be optimized, which is of great significance for the development of high-performance aqueous zinc-ion batteries. Attached Figure Description

[0018] Figure 1 MnO2 / (NiO) prepared in Example 1 of this invention 0.5 (MnO) 0.5 XRD pattern of the composite material; Figure 2 MnO2 / (NiO) prepared in Example 1 of this invention 0.5 (MnO) 0.5 SEM image of the composite material; Figure 3 MnO2 / (NiO) prepared in Example 1 of this invention 0.5 (MnO) 0.5 Constant current charge-discharge spectra of zinc-ion batteries assembled from composite materials at different current densities; Figure 4 The constant current charge-discharge spectra of the zinc-ion battery assembled from MnO2 material prepared in Comparative Example 1 of this invention under different current densities. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0020] The MnSO4·H2O, KMnO4, and NiCl2·6H2O selected in Examples 1 to 9 of this invention are all analytically pure compounds.

[0021] Example 1 Step 1: Weigh 0.3 mmol MnSO4·H2O and 1.7 mmol KMnO4, add them to 15 mL of deionized water, and stir with a magnetic stirrer at 500 rpm for 10 min to obtain a purple-red transparent solution. Then add 0.15 mmol NiCl2·6H2O to the solution and stir at 600 rpm for 30 min to obtain a dark brown mixed solution A, in which the number of Ni atoms accounts for 7% of the total number of Mn and Ni atoms. Step 2: Transfer the mixed solution A to a 25 mL polytetrafluoroethylene-lined stainless steel high-pressure reactor, seal it, and place it in a constant temperature oven. Heat the solution from room temperature to 180 °C at a rate of 5 °C / min and perform a hydrothermal reaction for 24 h. After naturally cooling to room temperature, remove the black precipitate and transfer it to a 50 mL centrifuge tube. Add 30 mL of deionized water, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, and wash twice with deionized water. Then add 30 mL of anhydrous ethanol, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, and wash twice with anhydrous ethanol. Place the washed precipitate in a vacuum drying oven and vacuum dry it at 60 °C and -0.09 MPa for 12 h to obtain powdered precursor B. Step 3: Place precursor B in a tube furnace and calcine at 300°C for 4 h in an air atmosphere to obtain MnO2 / (NiO). 0.5 (MnO) 0.5 Composite materials.

[0022] Example 2 Step 1: Weigh 0.2 mmol MnSO4·H2O and 1.2 mmol KMnO4, add them to 15 mL of deionized water, and stir with a magnetic stirrer at 500 rpm for 10 min to obtain a purple-red transparent solution. Then add 0.1 mmol NiCl2·6H2O to the solution and stir at 600 rpm for 30 min to obtain a dark brown mixed solution A, in which the number of Ni atoms accounts for 6.7% of the total number of Mn and Ni atoms. Step 2: Transfer the mixed solution A to a 25 mL polytetrafluoroethylene-lined stainless steel high-pressure reactor, seal it, and place it in a constant temperature oven. Heat the solution from room temperature to 150 °C at a heating rate of 5 °C / min for 30 h of hydrothermal reaction. After natural cooling to room temperature, remove the black precipitate and transfer it to a 50 mL centrifuge tube. Add 30 mL of deionized water, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, and wash twice with deionized water. Then add 30 mL of anhydrous ethanol, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, and wash twice with anhydrous ethanol. Place the washed precipitate in a vacuum drying oven and vacuum dry it at 60 °C and -0.09 MPa for 12 h to obtain powdered precursor B. Step 3: Place precursor B in a tube furnace and calcine at 300°C for 5 h in an air atmosphere to obtain MnO2 / (NiO). 0.5 (MnO)0.5 Composite materials.

[0023] Example 3 Step 1: Weigh 0.4 mmol MnSO4·H2O and 2 mmol KMnO4, add them to 20 mL of deionized water, and stir at 500 rpm for 10 min using a magnetic stirrer to obtain a purple-red transparent solution. Then add 0.2 mmol NiCl2·6H2O to the solution and stir at 600 rpm for 30 min to obtain a dark brown mixed solution A, in which the number of Ni atoms accounts for 7.7% of the total number of Mn and Ni atoms. Step 2: Transfer the mixed solution A to a 25 mL polytetrafluoroethylene-lined stainless steel high-pressure reactor, seal it, and place it in a constant temperature oven. Heat the solution from room temperature to 200 °C at a rate of 5 °C / min and perform a hydrothermal reaction for 15 h. After naturally cooling to room temperature, remove the black precipitate and transfer it to a 50 mL centrifuge tube. Add 30 mL of deionized water, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, and wash twice with deionized water. Then add 30 mL of anhydrous ethanol, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, and wash twice with anhydrous ethanol. Place the washed precipitate in a vacuum drying oven and vacuum dry it at 70 °C and -0.09 MPa for 10 h to obtain powdered precursor B. Step 3: Place precursor B in a tube furnace and calcine at 300°C for 4 h in an air atmosphere to obtain MnO2 / (NiO). 0.5 (MnO) 0.5 Composite materials.

[0024] Example 4 Step 1: Weigh 0.1 mmol MnSO4·H2O and 1 mmol KMnO4, add them to 10 mL of deionized water, and stir with a magnetic stirrer at 500 rpm for 10 min to obtain a purple-red transparent solution. Then add 0.3 mmol NiCl2·6H2O to the solution and stir at 600 rpm for 30 min to obtain a dark brown mixed solution A, in which the number of Ni atoms accounts for 21.4% of the total number of Mn and Ni atoms. Step 2: Transfer the mixed solution A to a 25 mL polytetrafluoroethylene-lined stainless steel high-pressure reactor, seal it, and place it in a constant temperature oven. Heat the solution from room temperature to 200 °C at a rate of 5 °C / min and perform a hydrothermal reaction for 24 h. After naturally cooling to room temperature, remove the black precipitate and transfer it to a 50 mL centrifuge tube. Add 30 mL of deionized water, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, and wash twice with deionized water. Then add 30 mL of anhydrous ethanol, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, and wash twice with anhydrous ethanol. Place the washed precipitate in a vacuum drying oven and vacuum dry it at 60 °C and -0.09 MPa for 12 h to obtain powdered precursor B. Step 3: Place precursor B in a tube furnace and calcine at 350°C for 4 h in an air atmosphere to obtain MnO2 / (NiO). 0.5 (MnO) 0.5 Composite materials.

[0025] Example 5 Step 1: Weigh 0.5 mmol MnSO4·H2O and 2.5 mmol KMnO4, add them to 25 mL of deionized water, and stir with a magnetic stirrer at 500 rpm for 10 min to obtain a purple-red transparent solution. Then add 0.25 mmol NiCl2·6H2O to the solution and stir at 600 rpm for 30 min to obtain a dark brown mixed solution A, in which the number of Ni atoms accounts for 7.7% of the total number of Mn and Ni atoms. Step 2: Transfer the mixed solution A to a 25 mL polytetrafluoroethylene-lined stainless steel high-pressure reactor, seal it, and place it in a constant temperature oven. Heat the solution from room temperature to 170 °C at a heating rate of 5 °C / min for 20 h of hydrothermal reaction. After natural cooling to room temperature, remove the black precipitate and transfer it to a 50 mL centrifuge tube. Add 30 mL of deionized water, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, and wash twice with deionized water. Then add 30 mL of anhydrous ethanol, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, and wash twice with anhydrous ethanol. Place the washed precipitate in a vacuum drying oven and vacuum dry it at 60 °C and -0.09 MPa for 12 h to obtain powdered precursor B. Step 3: Place precursor B in a tube furnace and calcine at 350°C for 4 h in an air atmosphere to obtain MnO2 / (NiO). 0.5 (MnO)0.5 Composite materials.

[0026] Example 6 Step 1: Weigh 0.12 mmol MnSO4·H2O and 1 mmol KMnO4, add them to 10 mL of deionized water, and stir with a magnetic stirrer at 500 rpm for 10 min to obtain a purple-red transparent solution. Then add 0.06 mmol NiCl2·6H2O to the solution and stir at 600 rpm for 30 min to obtain a dark brown mixed solution A, in which the number of Ni atoms accounts for 5% of the total number of Mn and Ni atoms. Step 2: Transfer the mixed solution A to a 25 mL polytetrafluoroethylene-lined stainless steel high-pressure reactor, seal it, and place it in a constant temperature oven. Heat the solution from room temperature to 160 °C at a rate of 5 °C / min and perform a hydrothermal reaction for 32 h. After naturally cooling to room temperature, remove the black precipitate and transfer it to a 50 mL centrifuge tube. Add 30 mL of deionized water, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, and wash twice with deionized water. Then add 30 mL of anhydrous ethanol, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, and wash twice with anhydrous ethanol. Place the washed precipitate in a vacuum drying oven and vacuum dry it at 50 °C and -0.09 MPa for 14 h to obtain powdered precursor B. Step 3: Place precursor B in a tube furnace and calcine at 250°C for 6 h in an air atmosphere to obtain MnO2 / (NiO). 0.5 (MnO) 0.5 Composite materials.

[0027] Example 7 Step 1: Weigh 0.25 mmol MnSO4·H2O and 1.5 mmol KMnO4, add them to 20 mL of deionized water, and stir with a magnetic stirrer at 500 rpm for 10 min to obtain a purple-red transparent solution. Then add 0.2 mmol NiCl2·6H2O to the solution and stir at 600 rpm for 30 min to obtain a dark brown mixed solution A, in which the number of Ni atoms accounts for 10.3% of the total number of Mn and Ni atoms. Step 2: Transfer the mixed solution A to a 25 mL polytetrafluoroethylene-lined stainless steel high-pressure reactor, seal it, and place it in a constant temperature oven. Heat the solution from room temperature to 190 °C at a heating rate of 5 °C / min for 18 h of hydrothermal reaction. After natural cooling to room temperature, remove the black precipitate and transfer it to a 50 mL centrifuge tube. Add 30 mL of deionized water, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, and wash twice with deionized water. Then add 30 mL of anhydrous ethanol, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, and wash twice with anhydrous ethanol. Place the washed precipitate in a vacuum drying oven and vacuum dry it at 70 °C and -0.09 MPa for 11 h to obtain powdered precursor B. Step 3: Place precursor B in a tube furnace and calcine at 400°C for 2 h in an air atmosphere to obtain MnO2 / (NiO). 0.5 (MnO) 0.5 Composite materials.

[0028] Example 8 Step 1: Weigh 0.1 mmol MnSO4·H2O and 1 mmol KMnO4, add them to 15 mL of deionized water, and stir with a magnetic stirrer at 500 rpm for 10 min to obtain a purple-red transparent solution. Then add 0.25 mmol NiCl2·6H2O to the solution and stir at 600 rpm for 30 min to obtain a dark brown mixed solution A, in which the number of Ni atoms accounts for 18.5% of the total number of Mn and Ni atoms. Step 2: Transfer the mixed solution A to a 25 mL polytetrafluoroethylene-lined stainless steel high-pressure reactor, seal it, and place it in a constant temperature oven. Heat the solution from room temperature to 200 °C at a rate of 5 °C / min and perform a hydrothermal reaction for 12 h. After naturally cooling to room temperature, remove the black precipitate and transfer it to a 50 mL centrifuge tube. Add 30 mL of deionized water, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, and wash twice with deionized water. Then add 30 mL of anhydrous ethanol, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, and wash twice with anhydrous ethanol. Place the washed precipitate in a vacuum drying oven and vacuum dry it at 50 °C and -0.09 MPa for 13 h to obtain powdered precursor B. Step 3: Place precursor B in a tube furnace and calcine at 250°C for 5 h in an air atmosphere to obtain MnO2 / (NiO). 0.5 (MnO)0.5 Composite materials.

[0029] Example 9 Step 1: Weigh 0.2 mmol MnSO4·H2O and 1.5 mmol KMnO4, add them to 10 mL of deionized water, and stir with a magnetic stirrer at 500 rpm for 10 min to obtain a purple-red transparent solution. Then add 0.3 mmol NiCl2·6H2O to the solution and stir at 600 rpm for 30 min to obtain a dark brown mixed solution A, in which the number of Ni atoms accounts for 15% of the total number of Mn and Ni atoms. Step 2: Transfer the mixed solution A to a 25 mL polytetrafluoroethylene-lined stainless steel high-pressure reactor, seal it, and place it in a constant temperature oven. Heat the solution from room temperature to 150 °C at a rate of 5 °C / min and perform a hydrothermal reaction for 36 h. After naturally cooling to room temperature, remove the black precipitate and transfer it to a 50 mL centrifuge tube. Add 30 mL of deionized water, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, and wash twice with deionized water. Then add 30 mL of anhydrous ethanol, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, and wash twice with anhydrous ethanol. Place the washed precipitate in a vacuum drying oven and vacuum dry it at 70 °C and -0.09 MPa for 10 h to obtain powdered precursor B. Step 3: Place precursor B in a tube furnace and calcine at 400°C for 3 h in an air atmosphere to obtain MnO2 / (NiO). 0.5 (MnO) 0.5 Composite materials.

[0030] Comparative Example 1 Step 1: Weigh 0.3 mmol MnSO4·H2O and 1.7 mmol KMnO4, add them to 15 mL of deionized water, and stir with a magnetic stirrer at 500 rpm for 10 min to obtain a purple-red transparent solution. Step 2: Transfer the purplish-red transparent solution to a 25 mL polytetrafluoroethylene-lined stainless steel high-pressure reactor. After sealing, place it in a constant temperature oven and heat it from room temperature to 180°C at a rate of 5°C / min. Perform a hydrothermal reaction for 24 hours. After naturally cooling to room temperature, remove the black precipitate and transfer it to a 50 mL centrifuge tube. Add 30 mL of deionized water, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, and wash twice with deionized water. Then add 30 mL of anhydrous ethanol, sonicate for 5 min, centrifuge at 8000 rpm for 5 min, discard the supernatant, and wash twice with anhydrous ethanol. Place the washed precipitate in a vacuum drying oven and vacuum dry it at 60°C and -0.09 MPa for 12 h to obtain a powdered precursor. Step 3: Place the precursor in a tube furnace and calcine it at 300°C for 4 h in an air atmosphere to obtain MnO2.

[0031] Figure 1 The MnO2 / (NiO) prepared in Example 1 0.5 (MnO) 0.5 The XRD pattern of the composite material shows that α-MnO2 and (NiO) 0.5 (MnO) 0.5 They coexist.

[0032] Figure 2 The MnO2 / (NiO) prepared in Example 1 0.5 (MnO) 0.5 The SEM image of the composite material shows that α-MnO2 is in the form of nanorods, and (NiO) 0.5 (MnO) 0.5 It is in the form of nanosheets, and (NiO) 0.5 (MnO) 0.5 There is a clear, atomically close heterogeneous interface between the phase and α-MnO2.

[0033] The MnO2 / (NiO) prepared in Example 1 0.5 (MnO) 0.5 Using composite materials as the positive electrode, zinc sheets as the negative electrode, a mixed aqueous solution of 2 M ZnSO4 and 0.1 M M M MnSO4 as the electrolyte, and glass fiber (GF / D) as the separator, a CR2025 coin cell zinc-ion battery was assembled. Constant current charge-discharge tests were conducted, and the results are shown in [link to results]. Figure 3 It can be seen that at 0.5, 1, 2, 3, 4, and 5 A·g -At current densities of ¹, the capacities were 306.3, 268.2, 219.3, 185.5, 162.6, and 144.2 mAh·g, respectively. - ¹.

[0034] Using MnO2 prepared in Comparative Example 1 as the positive electrode material, zinc sheet as the negative electrode, a mixed aqueous solution with a ZnSO4 concentration of 2 M and a MnSO4 concentration of 0.1 M as the electrolyte, and glass fiber (GF / D) as the separator, a CR2025 coin cell zinc-ion battery was assembled. Constant current charge-discharge tests were conducted, and the results are shown in [reference needed]. Figure 4 It can be seen that at 0.5, 1, 2, 3, 4, and 5 A·g - At current densities of ¹, the capacities were 158.6, 140, 116.7, 101.2, 91.5, and 83.5 mAh·g, respectively. - ¹.

[0035] By comparison Figure 3 and Figure 4 It can be seen that the MnO2 / (NiO) prepared in Example 1... 0.5 (MnO) 0.5 Zinc-ion batteries using composite materials as the positive electrode material operate at 0.5 A·g. - At a current density of ¹, the specific capacity reaches 306.3 mAh·g. - ¹, at 5 A·g - ¹At high current density, the specific capacity remains at 144.2 mAh·g - ¹, the specific capacity is much higher than that of the zinc-ion battery using MnO2 as the positive electrode material prepared in Comparative Example 1, indicating that the MnO2 / (NiO) prepared in Example 1 has a better specific capacity. 0.5 (MnO) 0.5 Composite materials can impart superior rate performance and structural stability to zinc ions.

Claims

1. A type of MnO2 / (NiO) 0.5 (MnO) 0.5 A method for preparing composite materials, characterized in that, Includes the following steps: Step 1: Weigh 0.1~0.5 mmol MnSO4·H2O and 1~2.5 mmol KMnO4, add them to 10~25 mL of deionized water, stir magnetically to obtain a purple-red transparent solution, then add 0.06~0.3 mmol NiCl2·6H2O to it, continue stirring to obtain mixed solution A; Step 2: Transfer the mixed solution A to a high-pressure reactor, seal it, place it in a constant temperature oven, and heat it from room temperature to 150~200℃ at a heating rate of 5℃ / min. Perform the hydrothermal reaction for 12~36 h, cool it naturally to room temperature, and wash and vacuum dry it in sequence to obtain precursor B. Step 3: Place precursor B in a tube furnace and calcine it at a heating rate of 5℃ / min from room temperature to 250~400℃ for 2~6 h in an air atmosphere to obtain MnO2 / (NiO). 0.5 (MnO) 0.5 Composite materials.

2. The MnO2 / (NiO) according to claim 1 0.5 (MnO) 0.5 A method for preparing composite materials, characterized in that, The atomic numbers of Mn and Ni in the mixed solution A of step 1 meet the condition that the atomic number of Ni accounts for 5% to 21.4% of the total atomic number of Mn and Ni.

3. The MnO2 / (NiO) according to claim 1 0.5 (MnO) 0.5 A method for preparing composite materials, characterized in that, In step 1, the amounts of MnSO4·H2O, KMnO4, deionized water, and NiCl2·6H2O were 0.3 mmol, 1.7 mmol, 15 mL, and 0.15 mmol, respectively.

4. The MnO2 / (NiO) according to claim 1 0.5 (MnO) 0.5 A method for preparing composite materials, characterized in that, The magnetic stirring in step 1 is performed using a magnetic stirrer at a speed of 500 rpm for 10 minutes; the stirring is then continued at a speed of 600 rpm for 30 minutes.

5. The MnO2 / (NiO) according to claim 1 0.5 (MnO) 0.5 A method for preparing composite materials, characterized in that, The hydrothermal reaction in step 2 involves heating from room temperature to 180°C at a rate of 5°C / min for 24 hours.

6. The MnO2 / (NiO) according to claim 1 0.5 (MnO) 0.5 A method for preparing composite materials, characterized in that, The washing process in step 2 involves washing the product three times each with deionized water and anhydrous ethanol.

7. The MnO2 / (NiO) according to claim 1 0.5 (MnO) 0.5 A method for preparing composite materials, characterized in that, The vacuum drying in step 2 is carried out at 50~70℃ for 10~14 h.

8. The MnO2 / (NiO) according to claim 1 0.5 (MnO) 0.5 A method for preparing composite materials, characterized in that, The calcination in step 3 is carried out in an air atmosphere, with the temperature increased from room temperature to 300°C at a heating rate of 5°C / min, and calcined for 4 hours.

9. A MnO2 / (NiO) prepared by the method according to any one of claims 1 to 8 0.5 (MnO) 0.5 Composite material, characterized in that, Ni enters the MnO2 lattice in the form of dopant, thereby growing nanosheet-like (NiO) in situ within the MnO2 matrix. 0.5 (MnO) 0.5 Phase, (NiO) 0.5 (MnO) 0.5 The phase forms an atomically close heterogeneous interface with the nanorod-shaped α-crystalline MnO2.

10. The MnO2 / (NiO) according to claim 9 0.5 (MnO) 0.5 Application of composite materials as cathode materials in aqueous zinc-ion batteries.

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