A method for preparing an electrode surface in situ to generate a manganese-based oxide active layer

Abstract

This invention provides a method for preparing an in-situ manganese-based oxide active layer on an electrode surface. The preparation method is cyclic voltammetric electrodeposition, belonging to the field of materials science. Specifically, untreated carbon cloth or manganese-based cathode material is used as the anode, and a polished zinc sheet is used as the cathode. Then, the anode and cathode are placed in an electrolyte, and a 2 mV s⁻¹ voltage is applied between the anode and cathode. ‑1 The method involves cycling at a specific voltage and performing 300 cycles at a scanning voltage. Since the electrodeposition conditions required by this method are the same as those for manganese-based aqueous zinc-ion batteries (ZIBs), it not only allows for the direct electrodeposition of ZnMn2O4 on carbon cloth as the cathode material for ZIBs, but also enables the in-situ construction of the ZnMn2O4 active layer at the manganese-based cathode material / electrolyte interface. This improves the poor electronic conductivity and stability of manganese-based cathode materials and enhances the electrochemical performance of ZIBs. Furthermore, this preparation method is simple, safe, green, efficient, and inexpensive, showing broad application prospects in high-performance energy storage devices.

Description

Technical Field

[0001] This invention belongs to the field of materials science, and in particular relates to a method for preparing an in-situ manganese-based oxide active layer on an electrode surface. Background Technology

[0002] Lithium-ion batteries are currently the most widely used electrochemical energy storage devices. However, due to the risk of long-term lithium resource shortages and the safety hazards posed by organic electrolytes, researchers are focusing on finding electrochemical energy storage systems with higher sustainability and economic efficiency. Among them, aqueous zinc-ion batteries (ZIBs) are one of the battery systems that are expected to be applied to large-scale energy storage systems due to their advantages such as abundant raw material sources, high safety, environmental friendliness, and high theoretical capacity.

[0003] As a core component of Zinc-based Inorganic Bismuth (ZIBs), constructing high-performance cathode materials is crucial. Among them, manganese-based oxides have attracted widespread attention and research due to their attractiveness in terms of high capacity and high energy density. Furthermore, due to their unique advantages such as low cost, abundant reserves, environmental friendliness, and diverse valence states and crystal structures, they are considered one of the most promising cathode materials suitable for aqueous Zinc-based Inorganic Bismuth (ZIBs).

[0004] However, the low electronic conductivity of manganese-based oxides limits their electrochemical performance. On the other hand, due to the high reactivity of water molecules, manganese-based cathode materials experience significant capacity decay during operation due to dissolution in aqueous media, directly leading to a series of problems such as poor rate capability and stability in zinc-ion batteries. Therefore, these key issues urgently need to be addressed to realize the application of zinc-ion batteries in large-scale energy storage. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing an in-situ manganese-based oxide active layer on an electrode surface, characterized by comprising the following steps:

[0006] S1: A two-electrode system is adopted, with carbon cloth and zinc sheet as the anode and cathode, respectively;

[0007] S2: Place the anode and cathode in the electrolyte and cycle them for 300-500 cycles in cyclic voltammetry mode to obtain the electrode material;

[0008] S3: The electrode material is cleaned with deionized water, and after cleaning, it is placed in an oven to dry at a constant temperature to obtain the manganese-based oxide electrode material prepared by cyclic voltammetry, thus completing the preparation of the manganese-based oxide active layer;

[0009] Furthermore, in S3, the manganese-based oxide electrode material is a self-supporting ZnMn2O4.

[0010] Furthermore, in S3, ZnMn2O4 is a self-supporting positive electrode material. After cleaning, the self-supporting positive electrode material does not require treatment with conductive agents and binders and can be used directly.

[0011] Furthermore, in S1, the carbon cloth does not require surface treatment, while the zinc sheet in S1 requires grinding.

[0012] Furthermore, in S2, the electrolyte comprises 2M ZnSO4 and 0.2M MnSO4.

[0013] Furthermore, in S2, the scanning voltage of the cyclic voltammetry is 2mV s. -1 The scanning window is 1-2V.

[0014] Furthermore, in S3, the constant temperature is 80℃ and the drying time is 2 hours.

[0015] Furthermore, manganese-based oxide electrode materials are used as electrode materials for aqueous zinc-ion batteries.

[0016] Furthermore, in S1, carbon-coated Mn3O4 can be used as the anode material, and S2-S3 can be repeated to achieve in-situ construction of the ZnMn2O4 active layer at the interface between the cathode and the electrolyte.

[0017] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in:

[0018] 1. This invention utilizes cyclic voltammetric electrodeposition to generate a ZnMn2O4 active layer on carbon cloth. Specifically, since the electrodeposition conditions required by this method are the same as those for manganese-based ZIBs, it can be used to construct an in-situ cathode / electrolyte interface active layer (CEI). This further improves the electrochemical performance of zinc-ion batteries and addresses the poor stability of manganese-based cathode materials.

[0019] 2. In the preparation method of the present invention, the anode and cathode materials are produced in large quantities and are inexpensive; the zinc-manganese ore obtained can be used directly after being deposited on carbon cloth and simply cleaned.

[0020] 3. This method is simple, green and efficient. The synthesis process does not require overly stringent experimental conditions or expensive chemical materials. Furthermore, the synthesis process is relatively safe and conforms to the concept of green chemistry. Attached Figure Description

[0021] Figure 1 SEM images of the zinc manganese ore ZnMn2O4 prepared in this invention (the sub-image shows the morphology under a higher magnification microscope);

[0022] Figure 2 Electronic images and EDS images (reflecting the distribution of various elements) of the zinc-manganese ore ZnMn2O4 prepared in this invention;

[0023] Figure 3 The XRD pattern of the zinc manganese ore ZnMn2O4 prepared in this invention;

[0024] Figure 4 , Figure 5 XPS spectrum of zinc manganese ore ZnMn2O4 prepared in this invention. Figure 4 Zn 2p; Figure 5 Mn 3s;

[0025] Figure 6 Cyclic voltammetry (CV) curves of the zinc manganese ore ZnMn2O4 prepared in this invention;

[0026] Figure 7 The charge-discharge curve of the zinc manganese ore ZnMn2O4 prepared in this invention;

[0027] Figure 8 Rate performance of the zinc-manganese ore ZnMn2O4 prepared in this invention;

[0028] Figure 9 SEM images of Mn3O4 / C cathode material before CEI construction;

[0029] Figure 10 SEM images of CEI constructed in situ for Mn3O4 / C cathode material using in-situ cyclic voltammetry.

[0030] Figure 11 TEM images of Mn3O4 / C after CEI construction;

[0031] Figure 12 Comparison of CV curves for Mn3O4 / C and after in-situ generation of ZnMn2O4 active layers on its surface (Mn3O4 / C-300CV);

[0032] Figure 13 A comparison of charge-discharge curves for Mn3O4 / C and for MnMn2O4 active layer generated in situ on its surface (Mn3O4 / C-300CV).

[0033] Figure 14 Cyclic stability test of Mn3O4 / C after in-situ generation of ZnMn2O4 active layer on Mn3O4 / C surface (Mn3O4 / C-300CV). Detailed Implementation

[0034] The following will describe in more detail a method for preparing an in-situ manganese-based oxide active layer on an electrode surface according to the present invention, with reference to schematic diagrams, which illustrate preferred embodiments of the present invention. It should be understood that those skilled in the art can modify the present invention described herein while still achieving the advantageous effects of the present invention. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the present invention.

[0035] Example 1

[0036] Synthesis and structural characterization of zinc manganese ore (ZnMn2O4) material.

[0037] In this embodiment, a two-electrode system is used, with carbon cloth (≈2cm) 2 A polished zinc sheet and a 2M ZnSO4 were used as the anode and cathode, respectively. The anode and cathode were then placed in an electrolyte (the main components of the electrolyte were 2M ZnSO4 and 0.2M NmSO4). Cyclic voltammetry was used with a scan voltage of 2 mV / s. -1 The process involves 300-500 cycles. Finally, the prepared electrode material is washed with deionized water and dried in an oven at 80°C for 2 hours to obtain a self-supporting manganese-based oxide electrode material, specifically a ZnMn2O4 electrode, prepared by cyclic voltammetry.

[0038] Scanning electron microscopy images of electrodeposited ZnMn2O4 are shown below. Figure 1 As shown, from Figure 1 It can be seen that the ZnMn2O4 film was successfully deposited on the carbon cloth, and the product is composed of tightly connected fine nanoparticles. Figure 2 The images show electron and EDS images of the ZnMn2O4 prepared in this invention. It can be seen that the deposition on the substrate surface is relatively uniform, and the elemental distribution photos show that the distribution of each element is very uniform. Figure 3 This is the X-ray diffraction pattern of the zinc manganese ore ZnMn2O4 prepared in this invention. In addition to the characteristic peaks corresponding to carbon cloth, the pattern also shows peaks at 2... θ The diffraction peaks at 33.0° and 36.4° are attributed to the (103) and (211) crystal planes of ZnMn2O4 (PDF00-024-1133), respectively, indicating that zinc manganese ore was successfully deposited on the substrate. Figure 4 and Figure 5 This is the X-ray photoelectron spectrum of the zinc manganese ore ZnMn2O4 prepared in this invention. Figure 4 In the Zn 2p region, the two characteristic peaks at 1021.2 eV and 1044.3 eV correspond to the binding energies of Zn 2p3 / 2 and Zn 2p1 / 2, respectively. Figure 5The Mn 3s spectrum shows that the average valence state of manganese is ≈3, indicating that ZnMn2O4 was successfully electrodeposited on carbon cloth after 300 cycles in cyclic voltammetry mode.

[0039] Example 2

[0040] Electrochemical performance testing of zinc manganese ore (ZnMn2O4) prepared by cyclic voltammetric electrodeposition.

[0041] CV curve: The CV curve can generally be directly measured using an electrochemical workstation. First, clamp the green clip of the electrochemical workstation to one side of the working electrode of the assembled battery, and the red clip (counter electrode) and white clip (reference electrode) to the other electrode. Then, select the CV test function and enter the parameter settings. The voltage is scanned from the initial potential to the upper limit potential and then to the lower limit potential. The slope of the voltage with respect to time is the scan rate. Finally, a closed curve is formed, which represents the redox reaction that occurs at the electrode in the electrochemical system. Charge-discharge curve: Install the test battery on the test instrument and place it in a test environment of (25±1)℃. Charge-discharge curve: The battery is charged at 0.2~5mA cm⁻¹. -2 The current is constant to charge to 1.85V, and then discharged to 1.0V.

[0042] In Example 1, electrodeposition was performed in cyclic voltammetry mode, and the CV curve obtained during the process is shown below. Figure 6 As shown in the figure, the significant difference between the first 5 cycles and the 200th cycle indicates that zinc manganese ore (ZnMn2O4) continuously deposits during this process, leading to a substantial increase in the battery system's capacity. It is speculated that the following reaction occurred during this process:

[0043]

[0044]

[0045] Figure 7 and Figure 8 The figures show the charge-discharge curves and rate curves of the ZnMn2O4 electrode material prepared in this invention at different current densities. The electrode maintains good capacity at lower rates, but at high current densities, the equilibrium of the electrodeposition reaction is broken, leading to capacity decay at high rates.

[0046] Example 3

[0047] Using carbon-coated Mn3O4 as the cathode material, an in-situ ZnMn2O4 active layer was constructed at the cathode / electrolyte interface, and its morphology was characterized and its electrochemical performance was tested. Preparation process:

[0048] (1) A two-electrode system was adopted, with Mn3O4 / C and polished zinc sheet as the anode and cathode, respectively.

[0049] (2) Place the anode and cathode in the electrolyte (the main components of the electrolyte are 2M ZnSO4 and 0.2M MnSO4). Use cyclic voltammetry mode with a scan voltage of 2mV s. -1 Repeat 300 cycles.

[0050] (3) The prepared electrode material is washed with deionized water and placed in an oven to dry at 80°C for 2 hours. The self-supporting electrode prepared by cyclic voltammetry can be obtained, and the in-situ construction of the ZnMn2O4 active layer at the positive electrode / electrolyte interface can be realized.

[0051] Figure 9 and Figure 10 The images show scanning electron microscope (SEM) images of Mn3O4 / C before and after 300 cycles in in-situ cyclic voltammetry mode, respectively. As shown in the figure, after the reaction, the surface of the Mn3O4 / C substrate is covered with an interfacial film. Figure 11 The image shows a TEM image of the sample. The nanoparticles have a diameter of about 10 nm, and the corresponding high-resolution TEM image shows clear lattice fringes. Figure 12 and Figure 13 The cyclic voltammetry (CV) curves and charge-discharge curves are compared for Mn3O4 / C and after the formation of a ZnMn2O4 active layer on its surface (Mn3O4 / C - 300CV). The cyclic voltammetry and charge-discharge curves show that the in-situ formation of the ZnMn2O4 active layer on the electrode surface can effectively improve the capacity of the Mn3O4 / C cathode. Furthermore, as... Figure 14 As shown, Mn3O4 / C-300CV exhibits excellent cycle stability. This further demonstrates the effectiveness and versatility of this method, which can be widely applied to the preparation of aqueous ion batteries and is easy to mass-produce.

[0052] In summary, this invention utilizes cyclic voltammetric electrodeposition to generate a ZnMn2O4 active layer on carbon cloth. Specifically, since the electrodeposition conditions required by this method are the same as those for manganese-based ZIBs, it can be used to construct an in-situ cathode / electrolyte interface active layer (CEI). This further improves the electrochemical performance of zinc-ion batteries and addresses the poor stability of manganese-based cathode materials. Furthermore, the anode and cathode materials are produced in large quantities and are inexpensive; the obtained zinc-manganese ore deposited on the carbon cloth can be used directly after simple cleaning. This method is simple, green, and efficient, without overly stringent experimental conditions or expensive chemical materials, and the synthesis process is relatively safe, aligning with the principles of green chemistry.

[0053] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the scope of protection of the present invention.

Claims

1. A method for preparing an in-situ manganese-based oxide active layer on an electrode surface, characterized in that, Includes the following steps: S1: A two-electrode system is adopted, with carbon-coated Mn3O4 and zinc sheet as the anode and cathode, respectively; S2: The anode and cathode are placed in an electrolyte comprising 2M ZnSO4 and 0.2M MnSO4. Cyclic voltammetry is used for 300 cycles, with a scan voltage of 2 mV / s. -1 The scanning window is 1-2 V to obtain the electrode material; S3: The electrode material is cleaned with deionized water, and after cleaning, it is placed in an oven for constant temperature drying. The constant temperature is 80°C and the drying time is 2 hours, thus realizing the in-situ construction of the ZnMn2O4 active layer at the interface between the positive electrode and the electrolyte.

2. The method for preparing an in-situ manganese-based oxide active layer on the electrode surface according to claim 1, characterized in that, In S3, the electrode material is self-supporting ZnMn2O4.

3. The method for preparing an in-situ manganese-based oxide active layer on the electrode surface according to claim 2, characterized in that, In step S3, the ZnMn2O4 is a self-supporting positive electrode material. After cleaning, the self-supporting positive electrode material does not require treatment with conductive agents and adhesives and can be used directly.

4. The method for preparing an in-situ manganese-based oxide active layer on the electrode surface according to claim 1, characterized in that, In step S1, the zinc sheet needs to be polished.

5. The method for preparing an in-situ manganese-based oxide active layer on the electrode surface according to claim 1, characterized in that, The electrode material is used as an electrode material for aqueous zinc-ion batteries.

Images