Preparation method of high-loading manganese dioxide electrode and deep electrochemical reconstruction method

Abstract

The invention discloses a preparation method of a high-loading manganese dioxide electrode and a deep electrochemical reconstruction method, and relates to the technical field of zinc ion batteries. The method comprises the following steps: placing a conductive substrate in a sodium salt solution for electrochemical oxidation; placing the oxidized conductive substrate in a manganese salt solution for electrochemical deposition; and placing the deposited conductive substrate in a strong alkali solution for electrochemical activation to obtain the manganese dioxide loaded on the conductive substrate. High loading and high activity can be easily realized through a high-temperature reconstruction promotion method. When the manganese dioxide is used as a positive electrode of an aqueous zinc ion battery, more excellent multiplying power and cycle performance can be obtained compared with manganese dioxide prepared by a conventional method.

Description

Technical Field

[0001] The present invention relates to the technical field of zinc ion batteries, and in particular to a method for preparing a high-loading manganese dioxide electrode and a deep electrochemical reconstruction method. Background Art

[0002] In recent years, with the development and utilization of fossil fuels such as coal, oil, and natural gas, the reserves of fossil energy have decreased sharply, the difficulty of mining has increased, and the carbon dioxide and toxic gases emitted have aggravated the greenhouse effect and air pollution. With the introduction of the dual carbon policy, seeking clean and pollution-free new energy has become a top priority for social development. Among them, new secondary energy storage devices have attracted much attention due to their low cost, high safety, high energy density, and high power density. At present, lithium-ion batteries are the most widely used, but during their use, there will be problems such as decomposition of positive electrode materials and ignition of organic electrolytes, which face safety challenges. Therefore, many researchers have turned their attention to safer aqueous batteries. Among them, zinc-ion batteries are considered to be one of the most likely new methods to replace lithium-ion batteries due to their advantages such as large current charging and discharging, high theoretical discharge capacity, high energy density, and high power density. They are expected to be used in large and medium-sized energy storage applications, such as grid-scale electrochemical energy storage, electric vehicles, mobile communications, and many other fields.

[0003] Manganese dioxide has become the most common positive electrode material for zinc-ion batteries due to its low cost, ability to provide high capacity, large voltage window and high output voltage. There are many methods for preparing manganese dioxide, and the crystal structure and morphology of manganese dioxide prepared by different preparation methods are different. Many reported works only synthesize a thin layer of active material on a conductive substrate to achieve high performance, but it is difficult to meet the needs of large-scale commercial applications, so the study of high-loading electrode materials is still a top priority in the development of energy storage.

[0004] Common preparation methods of manganese dioxide include liquid phase coprecipitation, sol-gel, hydrothermal, microemulsion, etc. These methods generally have complicated preparation processes, and the product morphology is difficult to control and difficult to achieve high loading. In addition, low-valent manganese-based oxides are often associated with the preparation process of manganese dioxide, and a variety of crystal forms are mixed to make it difficult to achieve high loading of manganese dioxide. Therefore, how to prepare a high loading manganese dioxide electrode with good rate and cycle performance is an important research direction in this field. Summary of the invention

[0005] In view of the deficiencies in the above-mentioned background technology, the present invention mainly addresses the problem that the preparation process of manganese dioxide in the prior art is often accompanied by low-valent manganese-based oxides, and that it is difficult to achieve high-loading manganese dioxide due to the mixing of multiple crystal forms. The present invention provides a preparation method for a high-loading manganese dioxide electrode and a deep electrochemical reconstruction method. The electrochemical method proposed in the present invention has a simple preparation process, an easy-to-operate process, and a uniform morphology of the prepared material. The high-temperature promoted reconstruction method can achieve a significant increase in loading and activity.

[0006] The first object of the present invention is to provide a method for preparing a high-loading manganese dioxide electrode, comprising the following steps: placing the conductive substrate in a sodium salt solution for electrochemical oxidation; placing the oxidized conductive substrate in a manganese salt solution for electrochemical deposition; The deposited conductive substrate is placed in a strong alkaline solution for electrochemical activation to obtain manganese dioxide supported on the conductive substrate; The conductive substrate includes carbon fiber paper, carbon fiber cloth or graphite paper.

[0007] Preferably, the sodium salt solution is prepared by uniformly dispersing the sodium salt in an aqueous solvent, and the concentration of the sodium salt solution is 0.5-1.5 mol / L; The sodium salt includes one or more of sodium chloride, sodium sulfate, sodium nitrate and sodium acetate.

[0008] Preferably, the manganese salt solution is prepared by uniformly dispersing the manganese salt in an aqueous solvent, and the concentration of the manganese salt solution is 0.01-0.03 mol / L; The manganese salt includes one or more of manganese chloride, manganese sulfate, manganese nitrate and manganese acetate.

[0009] Preferably, the strong alkali solution is prepared by dissolving a strong alkali in an aqueous solvent, and the concentration of the strong alkali solution is 0.5-1.5 mol / L; the strong alkali includes sodium hydroxide and / or potassium hydroxide.

[0010] Preferably, the temperature during the electrochemical oxidation is 0 to 85 o C, the oxidation time is 0.5~2.5min, and the oxidation voltage is 1~3V.

[0011] Preferably, the temperature during the electrochemical deposition is 20 to 85 o C, the deposition time is 5~25min, and the deposition voltage is -2~1V.

[0012] Preferably, the temperature during the electrochemical activation is 20 to 85 o C, the activation time is 10~20min, and the activation voltage is -1~2V.

[0013] The second object of the present invention is to provide a high-loading manganese dioxide electrode.

[0014] The third object of the present invention is to provide a high-loading manganese dioxide electrode for use in zinc ion batteries.

[0015] The fourth object of the present invention is to provide a zinc ion battery, which comprises a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte; wherein the positive electrode sheet is the above-mentioned high-loading manganese dioxide electrode.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for preparing a high-load manganese dioxide electrode and a deep electrochemical reconstruction method. The manganese dioxide synthesized by the temperature-controlled electrochemical method provided by the present invention is not only simple in preparation method, but also cheap and easy to obtain raw materials and can well control the product morphology. Among them, high loading and high activity can be easily achieved by a high-temperature promoted reconstruction method. It is used as the positive electrode of an aqueous zinc ion battery to obtain a more excellent rate and cycle performance than manganese dioxide prepared by a conventional method. The present invention regulates the loading of manganese-based hydroxide by regulating the temperature of electrochemical deposition, and finds that for the same electrochemical deposition time, the higher the deposition temperature, the higher the loading of manganese-based hydroxide. In addition, the present invention regulates the degree of reconstruction of the conversion of manganese-based hydroxide to manganese dioxide by regulating the temperature of electrochemical activation, and proposes the concept of "high temperature promoted reconstruction", that is, it is found that the higher the temperature of electrochemical activation, the higher the degree of reconstruction of the conversion of manganese-based hydroxide to manganese dioxide. The preparation of high-load manganese dioxide can be achieved by this method.

[0017] The low voltage used in the electrochemical deposition process will lead to the generation of low-valent manganese-based hydroxides, which are easily oxidized in the air and generally have low performance. Electrochemical activation methods are needed to promote their orderly transformation into high-valent manganese-based oxides to achieve better electrochemical performance. However, the conversion process involves the question of whether it is sufficient, so the "high temperature promoted reconstruction" method is introduced to promote its full transformation, so that excellent performance can be achieved.

[0018] The present invention adopts a high temperature promoted reconstruction method to successfully convert manganese hydroxide into high-load manganese dioxide more fully. The manganese dioxide obtained by the high temperature promoted reconstruction method of the present invention is used as the active material of the positive electrode plate, and the assembled zinc ion battery can achieve high rate performance and high cycle performance. Among them, the discharge specific capacity can reach 332.6mAh / g at a current density of 0.1A / g; there is no capacity decay after 3500 cycles at a current density of 2.0A / g. When its loading is as high as 9.88mg / cm 2 , at 0.2mA / cm 2The mass specific capacity can still reach 181.7 mAh / g and 1.8 mAh / cm 2 Area specific capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a scanning electron microscope image of the manganese dioxide prepared in Example 3.

[0020] Figure 2 It is the capacity performance diagram of the zinc ion battery in Examples 1 to 7.

[0021] Figure 3 This is the X-ray diffraction analysis diagram of the manganese dioxide prepared in Examples 1 to 4.

[0022] Figure 4 This is a rate performance diagram of the zinc ion battery in Example 3.

[0023] Figure 5 This is a cycle performance diagram of the zinc ion battery in Example 3 at a current density of 2.0 A / g.

[0024] Figure 6 This is a graph showing the change in the manganese dioxide loading prepared in Example 3 versus high temperature electrodeposition time.

[0025] Figure 7 This is a capacity performance diagram of the zinc ion battery at different current densities with different loading amounts in Example 3.

[0026] Figure 8 This is a scanning electron microscope image of the manganese dioxide prepared in Example 1. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention is further described below in conjunction with specific embodiments and drawings, but the embodiments are not intended to limit the present invention.

[0028] In order to achieve the above object, the first aspect of the present invention provides a method for preparing a high-loading manganese dioxide electrode, comprising the following steps: placing the conductive substrate in a sodium salt solution for electrochemical oxidation; placing the oxidized conductive substrate in a manganese salt solution for electrochemical deposition; The deposited conductive substrate is placed in a strong alkaline solution for electrochemical activation to obtain manganese dioxide supported on the conductive substrate; The conductive substrate includes carbon fiber paper, carbon fiber cloth or graphite paper.

[0029] Wherein, the sodium salt solution is prepared by uniformly dispersing the sodium salt in an aqueous solvent, and the concentration of the sodium salt solution is 0.5-1.5 mol / L; The sodium salt includes one or more of sodium chloride, sodium sulfate, sodium nitrate and sodium acetate.

[0030] The manganese salt solution is prepared by uniformly dispersing the manganese salt in a water solvent, and the concentration of the manganese salt solution is 0.01-0.03 mol / L; The manganese salt includes one or more of manganese chloride, manganese sulfate, manganese nitrate and manganese acetate.

[0031] The strong alkali solution is prepared by dissolving a strong alkali in an aqueous solvent, and the concentration of the strong alkali solution is 0.5-1.5 mol / L; the strong alkali includes sodium hydroxide and / or potassium hydroxide.

[0032] The temperature during the electrochemical oxidation is 0~85 o C, the oxidation time is 0.5~2.5min, and the oxidation voltage is 1~3V.

[0033] The temperature during the electrochemical deposition is 20 to 85 o C, the deposition time is 5~25min, and the deposition voltage is -2~1V.

[0034] The temperature during the electrochemical activation is 20 to 85 o C, the activation time is 10~20min, and the activation voltage is -1~2V.

[0035] In one embodiment, a method for preparing a high-loading manganese dioxide electrode is provided, and the specific preparation method includes: (1) dissolving sodium salt in ultrapure water and stirring to dissolve to obtain a sodium salt solution; (2) dissolving a manganese salt in ultrapure water and stirring to dissolve the manganese salt to obtain a manganese salt solution; (3) dissolving a strong base in ultrapure water and stirring to dissolve to obtain a strong base solution; (4) electrochemically oxidizing the conductive substrate in the sodium salt solution described in step (1), washing, and drying; (5) electrochemically depositing the material obtained in step (4) in the manganese salt solution described in step (2), washing, and drying; (6) The material obtained in step (5) is electrochemically activated in the strong alkaline solution described in step (3), washed, and dried to obtain the manganese dioxide.

[0036] The electrochemical method in step (4), step (5) and step (6) is carried out at a temperature of 0 to 85 o C.

[0037] The sodium salt in step (1) includes any one of sodium chloride, sodium sulfate, sodium nitrate or sodium acetate, or a combination of at least two thereof; the concentration of the sodium salt in the solution is 0.5-1.5 mol / L; The stirring rate of step (1) is 500-800 rpm; the dissolving temperature of step (1) is 0-85 o C; The dissolution time in step (1) is 20 to 60 minutes.

[0038] The manganese salt solution in step (2) comprises any one of manganese chloride, manganese sulfate, manganese nitrate or manganese acetate, or a combination of at least two thereof; the concentration of the manganese salt in the solution is 0.01-0.03 mol / L; The stirring rate of step (2) is 500-800 rpm; the dissolving temperature of step (2) is 20-85 o C; The dissolution time in step (2) is 20 to 60 minutes.

[0039] The strong alkali solution in step (3) includes sodium hydroxide and / or potassium hydroxide; the concentration of the strong alkali in the solution is 0.5-1.5 mol / L; the stirring rate in step (3) is 500-800 rpm; the dissolution temperature in step (3) is 0-85 o C; The dissolution time in step (3) is 20 to 60 minutes.

[0040] The application mode of the electrochemical oxidation in step (4) includes any one of LSV, CV, CP, It, and Et, or a combination of at least two thereof; the temperature of the electrochemical oxidation in step (4) is 0 to 85 o C; the time of the electrochemical oxidation in step (4) is 0.5~2.5min; the voltage of the electrochemical oxidation in step (4) is 1~3V.

[0041] The application mode of the electrochemical deposition in step (5) includes any one of LSV, CV, CP, It, and Et, or a combination of at least two thereof; the temperature of the electrochemical deposition in step (5) is 20 to 85 o C; the time of the electrochemical deposition in step (5) is 5 to 25 minutes; the voltage of the electrochemical deposition in step (5) is -2 to 1V.

[0042] The application mode of the electrochemical activation in step (6) includes any one of LSV, CV, CP, It, and Et, or a combination of at least two thereof; the temperature of the electrochemical activation in step (6) is 20 to 85 o C; the time of the electrochemical activation in step (6) is 10 to 20 minutes; the voltage of the electrochemical activation in step (6) is -1 to 2V.

[0043] The number of washings in steps (4), (5) and (6) is 3 to 6 times; wherein the washing is firstly performed with ultrapure water and then with ethanol; The drying temperature in steps (4), (5) and (6) is 20 to 60 o C; The drying time in steps (4), (5) and (6) is 3 to 6 hours; Specifically, the preparation method comprises the following steps: (1) Dissolve the sodium salt in ultrapure water at a stirring rate of 500-800 rpm and a dissolution temperature of 0-85 o C, dissolution time is 20~60min, and sodium salt solution is obtained; (2) Dissolve the manganese salt in ultrapure water at a stirring rate of 500-800 rpm and a dissolution temperature of 20-85 o C, the dissolution time is 20-60 min, and a manganese salt solution is obtained; (3) Dissolve the strong base in ultrapure water at a stirring rate of 500-800 rpm and a dissolution temperature of 0-85 o C, dissolution time is 20~60min, and a strong alkaline solution is obtained; (4) electrochemically oxidizing the conductive substrate in the sodium salt solution described in step (1) at a temperature of 0 to 85 o C, oxidation voltage is 1~3V, oxidation time is 0.5~2.5min, washing and drying; (5) electrochemically depositing the material obtained in step (4) in the manganese salt solution described in step (2) at a deposition temperature of 20 to 85 o C. Deposition voltage is -2~1V, deposition time is 5~25min, washing and drying; (6) The material obtained in step (5) is electrochemically activated in the strong alkaline solution described in step (3) at an activation temperature of 20 to 85 o C. The activation voltage is -1-2 V, the activation time is 10-20 min, and the manganese dioxide is obtained by washing and drying.

[0044] The second aspect of the present invention provides a high-loading manganese dioxide electrode. The high-loading manganese dioxide electrode is used as a positive electrode plate of a zinc ion battery, and the raw materials of the positive electrode plate of the zinc ion battery include a conductive substrate and an active material, and the raw materials of the active material include manganese dioxide, and the manganese dioxide is prepared by the above-mentioned preparation method of manganese dioxide.

[0045] A third aspect of the present invention provides an application of a high-loading manganese dioxide electrode in a zinc ion battery.

[0046] A fourth aspect of the present invention provides a zinc ion battery, comprising a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte; wherein the positive electrode sheet is a high-loading manganese dioxide electrode.

[0047] In addition, the negative electrode plate includes a zinc negative electrode; the diaphragm includes a glass fiber diaphragm; the electrolyte includes ZnSO4 / MnSO4; the concentration of the ZnSO4 solution is 1~3 mol / L; the concentration of the MnSO4 solution is 0.1~0.3 mol / L.

[0048] It should be noted that the experimental methods used in the present invention are all conventional methods unless otherwise specified; the reagents and materials used are all commercially available unless otherwise specified.

[0049] Example 1 This embodiment provides a method for preparing a high-loading manganese dioxide electrode and a positive electrode sheet for a zinc ion battery: Wherein, the preparation method of manganese dioxide comprises the following steps: (1) Dissolve 500 ml of NaSO4 (1 M) in ultrapure water at a stirring rate of 600 rpm and a dissolution temperature of 45 o C, dissolution time is 60min, and sodium salt solution is obtained; (2) Dissolve 500 ml of Mn(NO3)2 (0.02 M) in ultrapure water at a stirring rate of 500 rpm and a dissolution temperature of 25 o C, dissolution time is 30min, and manganese salt solution is obtained; (3) Dissolve 500 ml of KOH (1 M) in ultrapure water at a stirring rate of 600 rpm and a dissolution temperature of 25 o C, dissolution time is 40min, and a strong alkaline solution is obtained; (4) electrochemically oxidizing the conductive substrate in the sodium salt solution described in step (1) by the It method at an oxidation temperature of 25 o C, oxidation voltage is 2.5V, oxidation time is 1min, washing and drying; (5) The material obtained in step (4) is electrochemically deposited in the manganese salt solution described in step (2) by the It method at a deposition temperature of 80 o C. Deposition voltage is -1.5V, deposition time is 20min, washing and drying; (6) The material obtained in step (5) is electrochemically activated by the CV method in the strong alkaline solution described in step (3) at an activation temperature of 25 o C. The activation voltage is 0-0.7 V, the activation time is 13 min, and the manganese dioxide supported on the conductive substrate is obtained by washing and drying.

[0050] Preparation method of zinc ion battery positive electrode sheet: Since manganese dioxide is directly electrochemically synthesized on a conductive substrate, it is directly pressed into a positive electrode sheet with a diameter of 12 mm using a punch for use.

[0051] The capacity performance diagram of the zinc ion battery provided in this embodiment is as follows Figure 2 As shown, the X-ray diffraction analysis diagram of the positive electrode active material manganese dioxide provided in this embodiment is as follows Figure 3 As shown, the scanning electron microscope image of the positive electrode active material manganese dioxide provided in this embodiment is as shown Figure 8 shown.

[0052] Example 2 This embodiment provides a method for preparing a high-loading manganese dioxide electrode and a positive electrode sheet for a zinc ion battery: Wherein, the preparation method of manganese dioxide comprises the following steps: (1) Dissolve 500 ml of NaSO4 (1 M) in ultrapure water at a stirring rate of 600 rpm and a dissolution temperature of 45 o C, dissolution time is 60min, and sodium salt solution is obtained; (2) Dissolve 500 ml of Mn(NO3)2 (0.02 M) in ultrapure water at a stirring rate of 500 rpm and a dissolution temperature of 25 o C, dissolution time is 30min, and manganese salt solution is obtained; (3) Dissolve 500 ml of KOH (1 M) in ultrapure water at a stirring rate of 600 rpm and a dissolution temperature of 25 o C, dissolution time is 40min, and a strong alkaline solution is obtained; (4) electrochemically oxidizing the conductive substrate in the sodium salt solution described in step (1) by the It method at an oxidation temperature of 25 o C, oxidation voltage is 2.5V, oxidation time is 1min, washing and drying; (5) The material obtained in step (4) is electrochemically deposited in the manganese salt solution described in step (2) by the It method at a deposition temperature of 80 o C. Deposition voltage is -1.5V, deposition time is 20min, washing and drying; (6) The material obtained in step (5) is electrochemically activated in the strong alkaline solution described in step (3) by the CV method at an activation temperature of 60 o C. The activation voltage is 0-0.7 V, the activation time is 13 min, and the manganese dioxide supported on the conductive substrate is obtained by washing and drying.

[0053] Preparation method of zinc ion battery positive electrode sheet: Since manganese dioxide is directly electrochemically synthesized on a conductive substrate, it is directly pressed into a positive electrode sheet with a diameter of 12 mm using a punch for use.

[0054] The capacity performance diagram of the zinc ion battery provided in this embodiment is as follows Figure 2As shown, the X-ray diffraction analysis diagram of the positive electrode active material manganese dioxide provided in this embodiment is as follows Figure 3 shown.

[0055] Example 3 This embodiment provides a method for preparing a high-loading manganese dioxide electrode and a positive electrode sheet for a zinc ion battery: Wherein, the preparation method of manganese dioxide comprises the following steps: (1) Dissolve 500 ml of NaSO4 (1 M) in ultrapure water at a stirring rate of 600 rpm and a dissolution temperature of 45 o C, dissolution time is 60min, and sodium salt solution is obtained; (2) Dissolve 500 ml of Mn(NO3)2 (0.02 M) in ultrapure water at a stirring rate of 500 rpm and a dissolution temperature of 25 o C, dissolution time is 30min, and manganese salt solution is obtained; (3) Dissolve 500 ml of KOH (1 M) in ultrapure water at a stirring rate of 600 rpm and a dissolution temperature of 25 o C, dissolution time is 40min, and a strong alkaline solution is obtained; (4) electrochemically oxidizing the conductive substrate in the sodium salt solution described in step (1) by the It method at an oxidation temperature of 25 o C, oxidation voltage is 2.5V, oxidation time is 1min, washing and drying; (5) The material obtained in step (4) is electrochemically deposited in the manganese salt solution described in step (2) by the It method at a deposition temperature of 80 o C. Deposition voltage is -1.5V, deposition time is 20min, washing and drying; (6) The material obtained in step (5) is electrochemically activated in the strong alkaline solution described in step (3) by the CV method at an activation temperature of 80 o C. The activation voltage is 0-0.7 V, the activation time is 13 min, and the manganese dioxide supported on the conductive substrate is obtained by washing and drying.

[0056] Preparation method of zinc ion battery positive electrode sheet: Since manganese dioxide is directly electrochemically synthesized on a conductive substrate, it is directly pressed into a positive electrode sheet with a diameter of 12 mm using a punch for use.

[0057] The scanning electron microscope image of the positive electrode active material manganese dioxide provided in this embodiment is as follows Figure 1 As shown, the capacity performance diagram of the zinc ion battery provided in this embodiment is as follows Figure 2 As shown, the X-ray diffraction analysis diagram of the positive electrode active material manganese dioxide provided in this embodiment is as follows Figure 3As shown, the rate performance diagram of the zinc ion battery in this embodiment is as follows Figure 4 As shown, the cycle performance diagram of the zinc ion battery at a current density of 2.0A / g in this embodiment is as follows Figure 5 As shown in the figure, the amount of manganese dioxide loaded on the positive electrode active material provided in this embodiment varies with the high temperature electrodeposition time. Figure 6 As shown, the capacity performance diagram of the zinc ion battery with different loading amounts at different current densities in this embodiment is as follows Figure 7 shown.

[0058] Example 4 This embodiment provides a method for preparing a high-loading manganese dioxide electrode and a positive electrode sheet for a zinc ion battery: Wherein, the preparation method of manganese dioxide comprises the following steps: (1) Dissolve 500 ml of NaSO4 (1 M) in ultrapure water at a stirring rate of 600 rpm and a dissolution temperature of 45 o C, dissolution time is 60min, and sodium salt solution is obtained; (2) Dissolve 500 ml of Mn(NO3)2 (0.02 M) in ultrapure water at a stirring rate of 500 rpm and a dissolution temperature of 25 o C, dissolution time is 30min, and manganese salt solution is obtained; (3) Dissolve 500 ml of KOH (1 M) in ultrapure water at a stirring rate of 600 rpm and a dissolution temperature of 25 o C, dissolution time is 40min, and a strong alkaline solution is obtained; (4) electrochemically oxidizing the conductive substrate in the sodium salt solution described in step (1) by the It method at an oxidation temperature of 25 o C, oxidation voltage is 2.5V, oxidation time is 1min, washing and drying; (5) The material obtained in step (4) is electrochemically deposited in the manganese salt solution described in step (2) by the It method at a deposition temperature of 80 o C. Deposition voltage is -1.5V, deposition time is 20min, washing and drying; (6) The material obtained in step (5) is electrochemically activated in the strong alkaline solution described in step (3) by the CV method at an activation temperature of 90 o C. The activation voltage is 0-0.7 V, the activation time is 13 min, and the manganese dioxide supported on the conductive substrate is obtained by washing and drying.

[0059] Preparation method of zinc ion battery positive electrode sheet: Since manganese dioxide is directly electrochemically synthesized on a conductive substrate, it is directly pressed into a positive electrode sheet with a diameter of 12 mm using a punch for use.

[0060] The capacity performance diagram of the zinc ion battery provided in this embodiment is as follows Figure 2 As shown, the X-ray diffraction analysis diagram of the positive electrode active material manganese dioxide provided in this embodiment is as follows Figure 3 shown.

[0061] Example 5 This embodiment provides a method for preparing a high-loading manganese dioxide electrode and a positive electrode sheet for a zinc ion battery: Wherein, the preparation method of manganese dioxide comprises the following steps: (1) Dissolve 500 ml of NaSO4 (1 M) in ultrapure water at a stirring rate of 600 rpm and a dissolution temperature of 45 o C, dissolution time is 60min, and sodium salt solution is obtained; (2) Dissolve 500 ml of Mn(NO3)2 (0.02 M) in ultrapure water at a stirring rate of 500 rpm and a dissolution temperature of 25 o C, dissolution time is 30min, and manganese salt solution is obtained; (3) Dissolve 500 ml of KOH (1 M) in ultrapure water at a stirring rate of 600 rpm and a dissolution temperature of 25 o C, dissolution time is 40min, and a strong alkaline solution is obtained; (4) electrochemically oxidizing the conductive substrate in the sodium salt solution described in step (1) by the It method at an oxidation temperature of 25 o C, oxidation voltage is 2.5V, oxidation time is 1min, washing and drying; (5) The material obtained in step (4) is electrochemically deposited in the manganese salt solution described in step (2) by the It method at a deposition temperature of 25 o C. Deposition voltage is -1.5V, deposition time is 20min, washing and drying; (6) The material obtained in step (5) is electrochemically activated in the strong alkaline solution described in step (3) by the CV method at an activation temperature of 25 o C. The activation voltage is 0-0.7 V, the activation time is 13 min, and the manganese dioxide supported on the conductive substrate is obtained by washing and drying.

[0062] Preparation method of zinc ion battery positive electrode sheet: Since manganese dioxide is directly electrochemically synthesized on a conductive substrate, it is directly pressed into a positive electrode sheet with a diameter of 12 mm using a punch for use.

[0063] The capacity performance diagram of the zinc ion battery provided in this embodiment is as follows Figure 2 shown.

[0064] Example 6 This embodiment provides a method for preparing a high-loading manganese dioxide electrode and a positive electrode sheet for a zinc ion battery: Wherein, the preparation method of manganese dioxide comprises the following steps: (1) Dissolve 500 ml of NaSO4 (1 M) in ultrapure water at a stirring rate of 600 rpm and a dissolution temperature of 45 o C, dissolution time is 60min, and sodium salt solution is obtained; (2) Dissolve 500 ml of Mn(NO3)2 (0.02 M) in ultrapure water at a stirring rate of 500 rpm and a dissolution temperature of 25 o C, dissolution time is 30min, and manganese salt solution is obtained; (3) Dissolve 500 ml of KOH (1 M) in ultrapure water at a stirring rate of 600 rpm and a dissolution temperature of 25 o C, dissolution time is 40min, and a strong alkaline solution is obtained; (4) electrochemically oxidizing the conductive substrate in the sodium salt solution described in step (1) by the It method at an oxidation temperature of 25 o C, oxidation voltage is 2.5V, oxidation time is 1min, washing and drying; (5) The material obtained in step (4) is electrochemically deposited in the manganese salt solution described in step (2) by the It method at a deposition temperature of 50 o C. Deposition voltage is -1.5V, deposition time is 15min, washing and drying; (6) The material obtained in step (5) is electrochemically activated by the CV method in the strong alkaline solution described in step (3) at an activation temperature of 25 o C. The activation voltage is 0-0.7 V, the activation time is 13 min, and the manganese dioxide supported on the conductive substrate is obtained by washing and drying.

[0065] Preparation method of zinc ion battery positive electrode sheet: Since manganese dioxide is directly electrochemically synthesized on a conductive substrate, it is directly pressed into a positive electrode sheet with a diameter of 12 mm using a punch for use.

[0066] The capacity performance diagram of the zinc ion battery provided in this embodiment is as follows Figure 2 shown.

[0067] Example 7 This embodiment provides a method for preparing a high-loading manganese dioxide electrode and a positive electrode sheet for a zinc ion battery: Wherein, the preparation method of manganese dioxide comprises the following steps: (1) Dissolve 500 ml of NaSO4 (1 M) in ultrapure water at a stirring rate of 600 rpm and a dissolution temperature of 45 oC, dissolution time is 60min, and sodium salt solution is obtained; (2) Dissolve 500 ml of Mn(NO3)2 (0.02 M) in ultrapure water at a stirring rate of 500 rpm and a dissolution temperature of 25 o C, dissolution time is 30min, and manganese salt solution is obtained; (3) Dissolve 500 ml of KOH (1 M) in ultrapure water at a stirring rate of 600 rpm and a dissolution temperature of 25 o C, dissolution time is 40min, and a strong alkaline solution is obtained; (4) electrochemically oxidizing the conductive substrate in the sodium salt solution described in step (1) by the It method at an oxidation temperature of 25 o C, oxidation voltage is 2.5V, oxidation time is 1min, washing and drying; (5) electrochemically depositing the material obtained in step (4) in the manganese salt solution described in step (2) by the It method at a deposition temperature of 0 o C. The deposition voltage is -1.5V, the deposition time is 60min, and then washed and dried; (6) The material obtained in step (5) is electrochemically activated by the CV method in the strong alkaline solution described in step (3) at an activation temperature of 25 o C. The activation voltage is 0-0.7 V, the activation time is 13 min, and the manganese dioxide supported on the conductive substrate is obtained by washing and drying.

[0068] Preparation method of zinc ion battery positive electrode sheet: Since manganese dioxide is directly electrochemically deposited on a conductive substrate, it is directly pressed into a positive electrode sheet with a diameter of 12 mm using a punch for use.

[0069] The capacity performance diagram of the zinc ion battery provided in this embodiment is as follows Figure 2 shown.

[0070] In order to illustrate the relevant properties of the manganese dioxide provided by the present invention, it is described in conjunction with the accompanying drawings.

[0071] Figure 1 This is a scanning electron microscope image of the manganese dioxide prepared in Example 3. Figure 1 It was learned that ultrathin manganese dioxide nanosheets were uniformly grown on the large piece, indicating that the transformation of manganese dioxide nanosheets was more complete after high temperature-promoted reconstruction.

[0072] Figure 2 It is the capacity performance diagram of the zinc ion battery in Examples 1 to 7. Among them, Figure 2 (a) is a graph showing the mass specific capacity rate performance of the zinc ion batteries in Examples 1, 5 to 7 at different current densities; Figure 2(b) is the area specific capacity rate performance diagram of the zinc ion battery in Examples 1 to 4 at different current densities.

[0073] from Figure 2 (a) shows that compared with the manganese dioxide nanomaterials obtained in Examples 1, 6 and 7, the manganese dioxide nanomaterial obtained after low-temperature electrochemical deposition and low-temperature activation in Example 5 is more fully converted, so its mass specific capacity performance is higher; Figure 2 (b) shows that, compared with the manganese dioxide nanomaterials obtained in Examples 1 and 2, the manganese dioxide nanomaterial obtained after high temperature promoted reconstruction in Example 3 is more fully converted, so its area specific capacity performance is higher. Compared with the manganese dioxide nanomaterial obtained in Example 4, it can be confirmed that even if the temperature of the electrochemical activation process is increased, the conversion degree of the manganese dioxide nanomaterial will not change more significantly, so the capacity performance will not be improved.

[0074] Figure 3 The X-ray diffraction analysis diagram of the manganese dioxide prepared in Examples 1 to 4. Figure 3 It is known that the manganese dioxide nanomaterial obtained after high temperature promoted reconstruction in Example 3 is more fully converted than the manganese dioxide nanomaterial obtained in Examples 1 and 2. By comparing the manganese dioxide nanomaterial obtained in Example 4, it can be confirmed that even if the temperature of the electrochemical activation process is increased, the degree of conversion of the manganese dioxide nanomaterial will not be significantly improved.

[0075] Figure 4 It is the rate performance diagram of the zinc ion battery in Example 3. Figure 4 It can be seen that at a current density of 0.1A / g, a high specific capacity of about 330mAh / g can be achieved, with excellent rate performance.

[0076] Figure 5 This is a graph showing the cycle performance of the zinc ion battery at a current density of 2.0 A / g in Example 3. Figure 5 It can be seen that at a high current density of 2.0 A / g, the capacity does not decay after 3500 cycles, and has stable cycle performance.

[0077] Figure 6 The figure is a graph showing the change of the manganese dioxide loading amount prepared in Example 3 with the high temperature electrochemical deposition time. Figure 6 It can be seen that when electrochemical deposition is carried out under high temperature conditions, the loading amount of MnO2 active substances gradually increases with the increase of deposition time, thus conveniently achieving an increase in loading amount.

[0078] Figure 7 The capacity performance diagram of the zinc ion battery at different current densities with different loading amounts in Example 3. Figure 7 (a) is a graph showing the mass specific capacity rate performance of zinc ion batteries with different loading amounts at different current densities in Example 3; Figure 7 (b) is the area specific capacity rate performance diagram of the zinc ion battery in Example 3 at different loading amounts and different current densities; Figure 7 (c) The zinc ion battery in Example 3 with different loadings at 0.2 mA / cm 2 Mass / area specific capacity performance plot at current density.

[0079] Figure 8 This is a scanning electron microscope image of the manganese dioxide prepared in Example 1. Figure 8 It can be seen that the material prepared in Example 1 retains some larger nanosheets, indicating that it has not been completely converted into manganese dioxide nanosheets.

[0080] The present invention describes preferred embodiments and their effects. However, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0081] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high-loading manganese dioxide electrode, characterized in that: The following steps are involved: placing the conductive substrate in a sodium salt solution for electrochemical oxidation; placing the oxidized conductive substrate in a manganese salt solution for electrochemical deposition; The deposited conductive substrate is placed in a strong alkaline solution for electrochemical activation to obtain manganese dioxide supported on the conductive substrate; The conductive substrate includes carbon fiber paper, carbon fiber cloth or graphite paper.

2. The method for preparing a high-loading manganese dioxide electrode according to claim 1, characterized in that: The sodium salt solution is prepared by uniformly dispersing the sodium salt in an aqueous solvent, and the concentration of the sodium salt solution is 0.5-1.5 mol / L; The sodium salt includes one or more of sodium chloride, sodium sulfate, sodium nitrate and sodium acetate.

3. The method for preparing a high-loading manganese dioxide electrode according to claim 1, characterized in that: The manganese salt solution is prepared by uniformly dispersing the manganese salt in a water solvent, and the concentration of the manganese salt solution is 0.01-0.03 mol / L; The manganese salt includes one or more of manganese chloride, manganese sulfate, manganese nitrate and manganese acetate.

4. The method for preparing a high-loading manganese dioxide electrode according to claim 1, characterized in that: The strong alkali solution is prepared by dissolving a strong alkali in an aqueous solvent, and the concentration of the strong alkali solution is 0.5-1.5 mol / L; the strong alkali includes sodium hydroxide and / or potassium hydroxide.

5. The method for preparing a high-loading manganese dioxide electrode according to claim 1, characterized in that: The temperature during the electrochemical oxidation is 0~85 o C, the oxidation time is 0.5~2.5min, and the oxidation voltage is 1~3V.

6. The method for preparing a high-loading manganese dioxide electrode according to claim 1, characterized in that: The temperature during the electrochemical deposition is 20 to 85 o C, the deposition time is 5~25min, and the deposition voltage is -2~1V.

7. The method for preparing a high-loading manganese dioxide electrode according to claim 1, characterized in that: The temperature during the electrochemical activation is 20 to 85 o C, the activation time is 10~20min, and the activation voltage is -1~2V.

8. A high-loading manganese dioxide electrode prepared by the method according to any one of claims 1 to 7.

9. Use of the high-loading manganese dioxide electrode according to claim 8 in a zinc ion battery.

10. A zinc ion battery, characterized in that: The zinc ion battery comprises a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte; wherein the positive electrode sheet is the high-loading manganese dioxide electrode as described in claim 8.

Images