Manganese dioxide intercalated graphite material and method for preparing the same

Abstract

The application relates to the field of new materials and electrochemistry, in particular to a manganese dioxide intercalated graphite material and a preparation method thereof. First, graphite material forms an intercalation compound between graphite layers under the action of voltage in concentrated sulfuric acid, then in a peeling and depositing process, manganese ions are deposited between graphite layers and on the surface of the graphite under the action of voltage, the interlayer pi-pi interaction is weakened through an electrochemical method, the interlayer space of the graphite is effectively utilized, and therefore the later loading of active substances between the graphite layers is facilitated. Finally, the manganese dioxide intercalated graphite material with high performance is obtained, and has the characteristics of low cost and high efficiency.

Description

Technical Field

[0001] This invention relates to the fields of new materials and electrochemical technology, specifically to a manganese dioxide intercalated graphite material and its preparation method. Background Technology

[0002] Graphite intercalation compounds are a class of compounds formed by inserting atoms, molecules, or ions between two graphite layers using physical or chemical methods. They are substances situated between graphite and graphene, retaining the excellent physicochemical properties of graphite itself while also possessing new physicochemical properties due to the interactions between the intercalator and the graphite carbon atom layers, such as electron exchange and spatial confinement. These properties include high conductivity, high lubricity, ion exchange characteristics, and catalytic properties. Intercalators can be acids, alkali metals, fluorine, organic compounds, etc. Graphite intercalation compounds have wide applications in electrochemistry. Compared to pure graphite, exfoliation deposition of graphite intercalation compounds can fully utilize the graphite interlayers, thereby increasing the loading of active materials and significantly improving the electrochemical performance of the material. Furthermore, the use of electrochemical methods to prepare manganese dioxide intercalated graphite materials effectively improves the efficiency of traditional preparation processes and avoids pollution problems. Summary of the Invention

[0003] The purpose of this invention is to provide a manganese dioxide intercalated graphite material and its preparation method, which has the effect of rapidly intercalating active substances between graphite layers and improving the electrochemical performance of the material.

[0004] The present invention provides a method for preparing manganese dioxide intercalated graphite material, which can be achieved solely through electrochemical methods. First, graphite material forms graphite interlayer compounds in concentrated sulfuric acid under the action of voltage. Then, during the exfoliation deposition process, manganese ions are deposited in the graphite interlayers and on the surface under the action of voltage, effectively improving the utilization rate of the graphite interlayers while ensuring the organic combination between graphite and manganese dioxide, thereby increasing the active material loading of graphite and thus improving electrochemical performance.

[0005] The present invention provides a method for preparing manganese dioxide intercalated graphite material, which specifically includes the following steps: (1) Graphite material is used as the working electrode and placed in an electrolytic cell containing concentrated sulfuric acid solution. Graphite material is also used as the counter electrode. A certain voltage is applied to the working electrode to perform intercalation. After that, the working electrode is cleaned with deionized water to obtain a graphite intercalation compound. (2) Then, the graphite intercalation compound is placed in a solution containing manganese ions of a certain concentration as the working electrode for exfoliation deposition. After that, the working electrode is cleaned with deionized water and dried at room temperature to obtain manganese dioxide intercalated graphite material.

[0006] Furthermore, the graphite material mentioned in step (1) is any one of artificial graphite, natural graphite, or derived graphite materials (such as graphitized polyimide materials).

[0007] Furthermore, the graphite material mentioned in step (1) is graphitized polyimide or graphite paper.

[0008] Furthermore, in step (1) during intercalation, the applied voltage is +1.5~3V, the working electrode and the counter electrode are 1.3~2cm apart in the electrolytic cell and are placed parallel to each other, the intercalation time is 3~7 min, and the size of the counter electrode must be greater than or equal to the size of the working electrode. Preferably, the applied voltage is +2.1V or +2.7V, the distance between the working electrode and the counter electrode in the electrolytic cell is 1.5cm, and the intercalation time is 5min.

[0009] Furthermore, in step (2), during the stripping deposition process, the applied voltage is +8~12V, the working electrode and the counter electrode are 1.3~2cm apart in the electrolytic cell and are placed opposite each other, the stripping deposition time is 1~5 min, and the size of the counter electrode must be greater than or equal to the size of the working electrode. Preferably, the applied voltage is +10V, the distance between the working electrode and the counter electrode in the electrolytic cell is 1.5cm, and the stripping deposition time is 2 min.

[0010] Furthermore, in step (2), the manganese ion-containing solution can be one or more manganese salt solutions such as manganese sulfate, manganese chloride, and manganese acetate, and the concentration of the manganese ion-containing solution is between 0.2 and 0.7 M. Preferably, the concentration of the manganese ion-containing solution is 0.5 M.

[0011] The present invention also provides a manganese dioxide intercalated graphite material obtained by the above preparation method, wherein manganese dioxide material is inserted between the layers and manganese dioxide material is also deposited on the surface.

[0012] Compared with the prior art, the present invention has the following beneficial effects: To address the problem of low interlayer utilization in existing graphite technologies, this invention weakens interlayer π-π interactions through electrochemical methods, effectively utilizing the interlayer space of graphite and facilitating the subsequent loading of active materials between the graphite layers. The result is a manganese dioxide intercalated graphite material with high surface capacitance and high cycling stability, characterized by low cost and high efficiency. Attached Figure Description

[0013] Figure 1 Here are scanning electron microscope images of the manganese dioxide intercalated graphite material obtained in Example 1; Figure 2 These are transmission electron microscope images of the manganese dioxide intercalated graphite material obtained in Example 1; Figure 3The CV curves of the manganese dioxide intercalated graphite material obtained in Example 1 at different scan rates are shown. Detailed Implementation

[0014] To better understand the content of this invention, it will be further described below with reference to specific embodiments and accompanying drawings. The following embodiments are based on the technology of this invention and provide detailed implementation methods and operating steps, but the scope of protection of this invention is not limited to the following embodiments.

[0015] Strict personal protective measures must be taken during the operation to avoid burns from concentrated sulfuric acid.

[0016] Example 1: (1) Cut the graphitized polyimide into two 2×2cm sheets, which are used as the anode and cathode respectively. The two are placed in parallel opposite each other in the electrolytic cell, maintaining a distance of 1.5cm. Use concentrated sulfuric acid solution as electrolyte, apply a DC voltage of +2.7V to the anode, and after constant voltage intercalation for 5min, remove the graphitized polyimide after anode intercalation. Then wash with deionized water to obtain the graphite intercalation compound material. (2) The graphite intercalation compound material obtained in step (1) is used as the anode and the graphite paper of 2×2cm is used as the cathode. The two are placed in parallel opposite each other in the electrolytic cell, maintaining a distance of 1.5cm. A DC voltage of +10V is applied to the anode in a freshly prepared MnSO4 solution with a concentration of 0.5M. Constant voltage stripping deposition is performed for 2min. Then the anode material is removed, washed with deionized water, and dried at room temperature to obtain manganese dioxide intercalated graphite material.

[0017] Figure 1 These are scanning electron microscope (SEM) images of the manganese dioxide intercalated graphite material obtained in Example 1. Figure 1 It can be seen that manganese dioxide is evenly distributed on the surface and inside of the plate.

[0018] Figure 2 These are transmission electron microscope (TEM) images of the manganese dioxide intercalated graphite material obtained in Example 1. Figure 2 Manganese dioxide can be seen distributed between the graphite layers.

[0019] The electrochemical performance of the manganese dioxide intercalated graphite material obtained in this embodiment was evaluated using a three-electrode system. The prepared manganese dioxide intercalated graphite material was cut into 1×1 cm pieces and used as the working electrode, Ag / AgCl as the reference electrode, a 2×2 cm Pt sheet as the counter electrode, and 1M Na₂SO₄ as the electrolyte. The specific capacity of the electrode material was calculated using constant current charge-discharge test curves.

[0020] Figure 3 These are the CV curves of the manganese dioxide intercalated graphite material obtained in Example 1 at different scan rates. From... Figure 3It can be seen that the curve shape remains good even at high scan rates, indicating that it has good rate performance.

[0021] Example 2: (1) Cut the graphitized polyimide into two 2×2cm sheets, which are used as the anode and cathode respectively. The two sheets are placed in parallel opposite each other in the electrolytic cell, maintaining a distance of 1.5cm. Use concentrated sulfuric acid solution as electrolyte and apply a DC voltage of +2.1V to the anode. After constant voltage intercalation for 5min, remove the graphitized polyimide after anode intercalation and wash it with deionized water to obtain graphite interlayer compound material. (2) The graphite intercalation compound material obtained in step (1) is used as the anode and the graphite paper of 2×2cm is used as the cathode. The two are placed in parallel opposite each other in the electrolytic cell, maintaining a distance of 1.5cm. A DC voltage of +10V is applied to the anode in a freshly prepared MnSO4 solution with a concentration of 0.5M. Constant voltage stripping deposition is performed for 2min. Then the anode material is removed, washed with deionized water, and dried at room temperature to obtain manganese dioxide intercalated graphite material.

[0022] The electrochemical performance of the manganese dioxide intercalated graphite material obtained in this embodiment was evaluated using a three-electrode system. The prepared manganese dioxide intercalated graphite material was cut into 1×1 cm pieces and used as the working electrode, Ag / AgCl as the reference electrode, a 2×2 cm Pt sheet as the counter electrode, and 1M Na₂SO₄ as the electrolyte. The specific capacity of the electrode material was calculated using constant current charge-discharge test curves.

[0023] Example 3: (1) Cut the graphite paper into two 2×2cm sheets, which are used as the anode and cathode respectively. Place them in the electrolytic cell in parallel with each other, maintaining a distance of 1.5cm. Use concentrated sulfuric acid solution as electrolyte, apply a DC voltage of +1.5V to the anode, and after constant voltage intercalation for 5min, remove the graphite paper after anode intercalation, and wash it with deionized water to obtain graphite interlayer compound material. (2) The graphite intercalation compound material obtained in step (1) is used as the anode and the 2×2cm sheet graphite paper is used as the cathode. The two are placed in parallel opposite each other in the electrolytic cell, maintaining a distance of 1.5cm. A DC voltage of +10V is applied to the anode in a freshly prepared 0.5M MnSO4 solution. Constant voltage stripping deposition is performed for 2min. Then the anode material is removed, washed with deionized water, and dried at room temperature to obtain manganese dioxide intercalated graphite material.

[0024] The electrochemical performance of the manganese dioxide intercalated graphite material obtained in this embodiment was evaluated using a three-electrode system. The prepared manganese dioxide intercalated graphite material was cut into 1×1 cm pieces and used as the working electrode, Ag / AgCl as the reference electrode, a 2×2 cm Pt sheet as the counter electrode, and 1M Na₂SO₄ as the electrolyte. The specific capacity of the electrode material was calculated using constant current charge-discharge test curves.

[0025] Example 4: (1) Cut the graphite paper into two 2×2cm sheets, which are used as the anode and cathode respectively. The two are placed in parallel opposite each other in the electrolytic cell, maintaining a distance of 1.6cm. Use concentrated sulfuric acid solution as electrolyte, apply a DC voltage of +2.7V to the anode, and after constant voltage intercalation for 5min, remove the graphite paper after anode intercalation, and wash it with deionized water to obtain graphite intercalation compound material. (2) The graphite intercalation compound material obtained in step (1) is used as the anode and the graphite paper of 2×2cm is used as the cathode. The two are placed in parallel opposite each other in the electrolytic cell, maintaining a distance of 1.3cm. A DC voltage of +8V is applied to the anode in a freshly prepared Mn(OAc)2 solution with a concentration of 0.5M. Constant voltage stripping deposition is performed for 2 min. Then the anode material is removed, washed with deionized water, and dried at room temperature to obtain manganese dioxide intercalated graphite material.

[0026] The electrochemical performance of the manganese dioxide intercalated graphite material obtained in this embodiment was evaluated using a three-electrode system. The prepared manganese dioxide intercalated graphite material was cut into 1×1 cm pieces and used as the working electrode, Ag / AgCl as the reference electrode, a 2×2 cm Pt sheet as the counter electrode, and 1 M Na₂SO₄ as the electrolyte. The specific capacity of the electrode material was calculated using constant current charge-discharge test curves.

[0027] Comparative Example 1: A 2×2cm sheet of graphitized polyimide material was used as the anode, and a 2×2cm sheet of graphite paper was used as the cathode. The two were placed parallel to each other in an electrolytic cell, maintaining a distance of 1.5cm. A DC voltage of +10V was applied to the anode in a freshly prepared 0.5M MnSO4 solution, and the deposition was carried out under constant voltage for 2 minutes. Then, the anode material was removed, washed with deionized water, and dried at room temperature to obtain manganese dioxide graphite material.

[0028] The electrochemical performance of the material obtained in this embodiment was evaluated using a three-electrode system. The prepared material was cut into 1×1 cm pieces and used as the working electrode, Ag / AgCl as the reference electrode, a 2×2 cm Pt sheet as the counter electrode, and 1M Na₂SO₄ as the electrolyte. The specific capacity of the electrode material was calculated using constant current charge-discharge test curves.

[0029] Table 1 The table above shows the manganese dioxide intercalated graphite materials obtained in Examples 1-4 and the manganese dioxide graphite material obtained in Comparative Example 1, respectively, as electrode materials at 10 mA cm⁻¹. -2 The discharge specific capacity at the specified current density indicates that the intercalated material has superior electrochemical performance.

[0030] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. The present invention can also have other embodiments based on the above structure and function, which will not be listed hereafter. Therefore, any simple modifications, equivalent changes, and alterations made by those skilled in the art to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a manganese dioxide intercalated graphite material, characterized in that, Specifically, the following steps are included: (1) Graphite material is used as the working electrode and placed in an electrolytic cell containing concentrated sulfuric acid solution. Graphite material is also used as the counter electrode. A certain voltage is applied to the working electrode to perform intercalation. After that, the working electrode is cleaned with deionized water to obtain a graphite intercalation compound. (2) Then, the graphite intercalation compound is placed in a solution containing manganese ions of a certain concentration as the working electrode for exfoliation deposition. After that, the working electrode is cleaned with deionized water and dried at room temperature to obtain manganese dioxide intercalated graphite material.

2. A method for preparing manganese dioxide intercalated graphite material as described in claim 1, characterized in that, The graphite material mentioned in step (1) is one of artificial graphite, natural graphite or derived graphite material.

3. A method for preparing manganese dioxide intercalated graphite material as described in claim 1, characterized in that, The graphite material mentioned in step (1) is graphitized polyimide or graphite paper.

4. A method for preparing manganese dioxide intercalated graphite material as described in claim 1, characterized in that, In step (1) during intercalation, a voltage of +1.5~3V is applied. The working electrode and the counter electrode are 1.3~2cm apart in the electrolytic cell and are placed in parallel opposite each other. The size of the counter electrode must be greater than or equal to the size of the working electrode.

5. A method for preparing manganese dioxide intercalated graphite material as described in claim 1, characterized in that, The intercalation time in step (1) is 3 to 7 minutes.

6. A method for preparing a manganese dioxide intercalated graphite material as described in claim 1, characterized in that, During the stripping deposition process in step (2), the applied voltage is +8~12V, the working electrode and the counter electrode are 1.3~2cm apart in the electrolytic cell and are placed opposite each other, and the size of the counter electrode must be greater than or equal to the size of the working electrode.

7. A method for preparing manganese dioxide intercalated graphite material as described in claim 1, characterized in that, In step (2), the stripping deposition time is 1~5 min.

8. A method for preparing a manganese dioxide intercalated graphite material as described in claim 1, characterized in that, The manganese-containing solution in step (2) is one or more of the manganese-containing solutions such as manganese sulfate, manganese chloride, and manganese acetate.

9. A method for preparing manganese dioxide intercalated graphite material as described in claim 1, characterized in that, The concentration of the manganese ion-containing solution in step (2) is 0.2~0.7M.

10. A manganese dioxide intercalated graphite material obtained by the preparation method according to any one of claims 1-9, characterized in that, Manganese dioxide material is inserted between its layers, and manganese dioxide material is also deposited on its surface.

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