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

Abstract

The application 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, so as to obtain the conductive substrate loaded with manganese dioxide. The high-temperature promotion reconstruction method can easily realize high loading and high activity. When the conductive substrate loaded with manganese dioxide is used as a positive electrode of a water-based zinc ion battery, the rate and cycle performance of the manganese dioxide prepared by the method are more excellent than those of manganese dioxide prepared by a conventional method.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of zinc ion batteries, in particular to a preparation method of a high-loading manganese dioxide electrode and a deep electrochemical reconstruction method. BACKGROUND

[0002] In recent years, with the development and utilization of fossil fuels such as coal, oil and natural gas, the reserves of fossil energy are rapidly decreasing, the mining difficulty is increasing, and the emitted carbon dioxide and toxic gases intensify the greenhouse effect and air pollution. With the proposal of the double carbon policy, seeking clean and pollution-free new energy has become the top priority of social development. Among them, new secondary energy storage devices are attracting attention due to their low cost, high safety, high energy density and high power density. At present, the most widely used is lithium ion battery, but problems such as decomposition of positive electrode material and fire and combustion of organic electrolyte may occur during use, and safety challenges are faced. Therefore, many researchers turn their attention to the more secure aqueous batteries. Among them, zinc ion batteries are considered one of the most likely new methods to replace lithium ion batteries due to their high current charge and discharge, high theoretical discharge capacity, high energy density and high power density, and are expected to be applied 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 is the most common positive electrode material for zinc ion batteries due to its low cost, 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 in order to achieve high performance, but it is difficult to meet the needs of commercial large-scale practical applications, so research on high-loading electrode materials is still the top priority for energy storage development.

[0004] Common preparation methods of manganese dioxide include liquid co-precipitation, sol-gel, hydrothermal method, microemulsion method, etc. These methods generally have complex preparation processes, and the product morphology is difficult to control and high loading is difficult to achieve. Moreover, low-valence manganese oxides and various crystal types often coexist during the preparation of manganese dioxide, making it difficult to achieve high-loading manganese dioxide. Therefore, how to prepare a high-loading manganese dioxide electrode with good rate and cycle performance is an important research direction in the field. SUMMARY

[0005] In view of the deficiencies in the above background art, the present application is mainly aimed at the problems that low-valence manganese-based oxides are often associated in the preparation process of manganese dioxide in the prior art, and various crystal forms are mixed, which makes it difficult to achieve high-loading manganese dioxide. The present application provides a preparation method and a deep electrochemical reconstruction method of high-loading manganese dioxide electrode. The electrochemical method proposed in the present application has simple preparation process, easy operation, and uniform material morphology. Through the high-temperature promotion reconstruction method, the loading capacity and activity can be greatly improved.

[0006] The first object of the present application is to provide a preparation method of high-loading manganese dioxide electrode, comprising the following steps:

[0007] placing the conductive substrate in a sodium salt solution for electrochemical oxidation;

[0008] placing the oxidized conductive substrate in a manganese salt solution for electrochemical deposition;

[0009] placing the deposited conductive substrate in a strong alkali solution for electrochemical activation, thereby obtaining the conductive substrate loaded with manganese dioxide;

[0010] The conductive substrate includes carbon fiber paper, carbon fiber cloth or graphite paper.

[0011] Preferably, the sodium salt solution is prepared by uniformly dispersing sodium salt in an aqueous solvent, and the concentration of the sodium salt solution is 0.5-1.5 mol / L.

[0012] The sodium salt includes one or more of sodium chloride, sodium sulfate, sodium nitrate and sodium acetate.

[0013] Preferably, the manganese salt solution is prepared by uniformly dispersing manganese salt in an aqueous solvent, and the concentration of the manganese salt solution is 0.01-0.03 mol / L.

[0014] The manganese salt includes one or more of manganese chloride, manganese sulfate, manganese nitrate and manganese acetate.

[0015] Preferably, the strong alkali solution is prepared by dissolving 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.

[0016] Preferably, the temperature during electrochemical oxidation is 0-85 o C, the oxidation time is 0.5-2.5 min, and the oxidation voltage is 1-3 V.

[0017] Preferably, the temperature during electrochemical deposition is 20-85 o C, the deposition time is 5-25 min, and the deposition voltage is -2-1 V.

[0018] Preferably, the temperature during the electrochemical activation is 20-85 o C, the activation time is 10-20 min, and the activation voltage is -1-2 V.

[0019] A second object of the present application is to provide a high-loading manganese dioxide electrode.

[0020] A third object of the present application is to provide an application of the high-loading manganese dioxide electrode in a zinc ion battery.

[0021] A fourth object of the present application 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 high-loading manganese dioxide electrode described above.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] The present application provides a preparation method of a high-loading manganese dioxide electrode and a deep electrochemical reconstruction method. The manganese dioxide synthesized by the temperature-controlled electrochemical method is not only simple in preparation method, cheap and easy to obtain in raw materials, but also can well control the morphology of the product. Among them, the high-loading and high-activity can be easily realized by the high-temperature reconstruction method. When used as the positive electrode of the aqueous zinc ion battery, the manganese dioxide prepared by the method has more excellent rate and cycle performance than the manganese dioxide prepared by the conventional method. The present application adjusts the loading of manganese-based hydroxide by controlling the temperature of electrochemical deposition, and finds that the higher the deposition temperature, the higher the loading of manganese-based hydroxide under the same electrochemical deposition time. In addition, the present application adjusts the reconstruction degree of the conversion of manganese-based hydroxide to manganese dioxide by controlling the temperature of electrochemical activation, and proposes the concept of "high-temperature reconstruction", i.e. the higher the temperature of electrochemical activation, the higher the reconstruction degree of the conversion of manganese-based hydroxide to manganese dioxide. The high-loading manganese dioxide can be prepared by this method.

[0024] The low voltage used in the electrochemical deposition process will lead to the generation of low-valence manganese-based hydroxide, which is easily oxidized in air and generally has low performance. It is necessary to use the electrochemical activation method to promote the orderly conversion of the low-valence manganese-based hydroxide to high-valence manganese-based oxide, so as to achieve more excellent electrochemical performance. However, the conversion process will involve the problem of whether it is sufficient, so the "high-temperature reconstruction" method is introduced to promote the sufficient conversion, so as to achieve excellent performance.

[0025] The present application adopts a high-temperature reconstruction method to successfully convert manganese hydroxide into high-loading manganese dioxide more fully. The manganese dioxide obtained by the high-temperature reconstruction method in the present application serves as an active material of a positive electrode sheet, and the assembled zinc ion battery can achieve high rate performance and high cycle performance. Among them, a discharge specific capacity of 332.6 mAh / g can be achieved at a current density of 0.1 A / g; no capacity attenuation occurs after 3500 cycles at a current density of 2.0 A / g. When the loading thereof is as high as 9.88 mg / cm 2 , a mass specific capacity of 181.7 mAh / g and an area specific capacity of 1.8 mAh / cm 2 can still be achieved at a current density of 0.2 mA / cm 2 . BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A scanning electron microscope image of the manganese dioxide prepared in Example 3.

[0027] Figure 2 A capacity performance graph of the zinc ion battery in Examples 1-7.

[0028] Figure 3 An X-ray diffraction analysis graph of the manganese dioxide prepared in Examples 1-4.

[0029] Figure 4 A rate performance graph of the zinc ion battery in Example 3.

[0030] Figure 5 A cycle performance graph of the zinc ion battery in Example 3 at a current density of 2.0 A / g.

[0031] Figure 6 A graph of the loading of the manganese dioxide prepared in Example 3 varying with high-temperature electrodeposition time.

[0032] Figure 7 A capacity performance graph of the zinc ion battery in Example 3 at different loadings at different current densities.

[0033] Figure 8 A scanning electron microscope image of the manganese dioxide prepared in Example 1. DETAILED DESCRIPTION

[0034] In order for those skilled in the art to better understand the technical solutions of the present application and to implement them, the present application is further described below in conjunction with specific embodiments and drawings, but the embodiments are not limiting of the present application.

[0035] In order to achieve the above-mentioned purpose, the present application provides, in a first aspect, a preparation method of a high-loading manganese dioxide electrode, comprising the following steps:

[0036] placing the conductive substrate in a sodium salt solution for electrochemical oxidation;

[0037] placing the oxidized conductive substrate in a manganese salt solution for electrochemical deposition;

[0038] placing the deposited conductive substrate in a strong alkali solution for electrochemical activation to obtain the conductive substrate loaded with manganese dioxide;

[0039] The conductive substrate includes carbon fiber paper, carbon fiber cloth or graphite paper.

[0040] The sodium salt solution is prepared by uniformly dispersing sodium salt in an aqueous solvent, and the concentration of the sodium salt solution is 0.5-1.5 mol / L.

[0041] The sodium salt includes one or more of sodium chloride, sodium sulfate, sodium nitrate and sodium acetate.

[0042] The manganese salt solution is prepared by uniformly dispersing manganese salt in an aqueous solvent, and the concentration of the manganese salt solution is 0.01-0.03 mol / L.

[0043] The manganese salt includes one or more of manganese chloride, manganese sulfate, manganese nitrate and manganese acetate.

[0044] The strong alkali solution is prepared by dissolving 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.

[0045] The temperature during the electrochemical oxidation is 0-85 o C, the oxidation time is 0.5-2.5 min, and the oxidation voltage is 1-3 V.

[0046] The temperature during the electrochemical deposition is 20-85 o C, the deposition time is 5-25 min, and the deposition voltage is -2-1 V.

[0047] The temperature during the electrochemical activation is 20-85 o C, the activation time is 10-20 min, and the activation voltage is -1-2 V.

[0048] In an embodiment, a method for preparing a high-loading manganese dioxide electrode is provided, and the specific preparation method includes:

[0049] (1) dissolving sodium salt in ultrapure water to obtain a sodium salt solution by stirring and dissolving;

[0050] (2) dissolving manganese salt in ultrapure water to obtain a manganese salt solution by stirring and dissolving;

[0051] (3) dissolving strong alkali in ultrapure water to obtain a strong alkali solution by stirring and dissolving;

[0052] (4) electrochemically oxidizing the conductive substrate in the sodium salt solution of step (1), washing and drying;

[0053] (5) electrochemically depositing the material obtained in step (4) in the manganese salt solution of step (2), washing and drying;

[0054] (6) electrochemically activating the material obtained in step (5) in the strong alkali solution of step (3), washing and drying to obtain the manganese dioxide.

[0055] wherein the temperature of the electrochemical method of step (4), step (5) and step (6) is 0~85 o C.

[0056] The sodium salt of step (1) includes any one or a combination of at least two of sodium chloride, sodium sulfate, sodium nitrate or sodium acetate; the concentration of the sodium salt in the solution is 0.5~1.5mol / L;

[0057] The stirring rate of step (1) is 500~800rpm; the temperature of the dissolution of step (1) is 0~85 o C; the time of the dissolution of step (1) is 20~60min.

[0058] The manganese salt solution of step (2) includes any one or a combination of at least two of manganese chloride, manganese sulfate, manganese nitrate or manganese acetate; the concentration of the manganese salt in the solution is 0.01~0.03mol / L;

[0059] The stirring rate of step (2) is 500~800rpm; the temperature of the dissolution of step (2) is 20~85 o C; the time of the dissolution of step (2) is 20~60min.

[0060] The strong alkali solution of step (3) includes sodium hydroxide and / or potassium hydroxide; the concentration of the strong alkali in the solution is 0.5~1.5mol / L; the stirring rate of step (3) is 500~800rpm; the temperature of the dissolution of step (3) is 0~85 o C; the time of the dissolution of step (3) is 20~60min.

[0061] The application mode of the electrochemical oxidation of step (4) includes any one or a combination of at least two of LSV, CV, CP, I-t, E-t; the temperature of the electrochemical oxidation of step (4) is 0~85 o C; the time of the electrochemical oxidation of step (4) is 0.5~2.5min; the voltage of the electrochemical oxidation of step (4) is 1~3V.

[0062] The application mode of the electrochemical deposition in step (5) includes any one or a combination of at least two of LSV, CV, CP, I-t, and E-t; the temperature of the electrochemical deposition in step (5) is 20-85 o C; the time of the electrochemical deposition in step (5) is 5-25 min; and the voltage of the electrochemical deposition in step (5) is -2-1 V.

[0063] The application mode of the electrochemical activation in step (6) includes any one or a combination of at least two of LSV, CV, CP, I-t, and E-t; the temperature of the electrochemical activation in step (6) is 20-85 o C; the time of the electrochemical activation in step (6) is 10-20 min; and the voltage of the electrochemical activation in step (6) is -1-2 V.

[0064] The number of times of washing in steps (4), (5), and (6) is 3-6 times; wherein, the washing is performed in the order of ultrapure water washing and ethanol washing;

[0065] The temperature of drying in steps (4), (5), and (6) is 20-60 o C;

[0066] The time of drying in steps (4), (5), and (6) is 3-6 h;

[0067] Specifically, the preparation method includes the following steps:

[0068] (1) Dissolve the sodium salt in ultrapure water, the stirring rate is 500-800 rpm, the dissolving temperature is 0-85 o C, and the dissolving time is 20-60 min to obtain a sodium salt solution;

[0069] (2) Dissolve the manganese salt in ultrapure water, the stirring rate is 500-800 rpm, the dissolving temperature is 20-85 o C, and the dissolving time is 20-60 min to obtain a manganese salt solution;

[0070] (3) Dissolve the strong base in ultrapure water, the stirring rate is 500-800 rpm, the dissolving temperature is 0-85 o C, and the dissolving time is 20-60 min to obtain a strong base solution;

[0071] (4) Electrochemically oxidize the conductive substrate in the sodium salt solution in step (1), the oxidation temperature is 0-85 o C, the oxidation voltage is 1-3 V, the oxidation time is 0.5-2.5 min, and then wash and dry;

[0072] (5) The material obtained in step (4) is subjected to electrochemical deposition in the manganese salt solution described in step (2), the deposition temperature is 20-85 o C, the deposition voltage is -2-1V, the deposition time is 5-25min, and washing and drying are performed.

[0073] (6) The material obtained in step (5) is subjected to electrochemical activation in the strong alkali solution described in step (3), the activation temperature is 20-85 o C, the activation voltage is -1-2V, the activation time is 10-20min, and washing and drying are performed to obtain the manganese dioxide.

[0074] The second aspect of the present application provides a high-loading manganese dioxide electrode. The high-loading manganese dioxide electrode is used as a zinc ion battery positive electrode sheet. The raw material of the zinc ion battery positive electrode sheet comprises a conductive substrate and an active material. The raw material of the active material comprises manganese dioxide, and the manganese dioxide is prepared by the preparation method of the manganese dioxide.

[0075] The third aspect of the present application provides an application of a high-loading manganese dioxide electrode in a zinc ion battery.

[0076] The fourth aspect of the present application provides a zinc ion battery. The zinc ion battery comprises a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte. The positive electrode sheet is a high-loading manganese dioxide electrode.

[0077] In addition, the negative electrode sheet comprises a zinc negative electrode, the separator comprises a glass fiber separator, the electrolyte comprises ZnSO4 / MnSO4, the concentration of the ZnSO4 solution is 1-3mol / L, and the concentration of the MnSO4 solution is 0.1-0.3mol / L.

[0078] It should be noted that, in the present application, the experimental methods are conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified.

[0079] Example 1

[0080] The present embodiment provides a preparation method of a high-loading manganese dioxide electrode and a zinc ion battery positive electrode sheet:

[0081] The preparation method of the manganese dioxide comprises the following steps:

[0082] (1) 500ml of NaSO4(1M) is dissolved in ultrapure water, the stirring rate is 600rpm, the dissolution temperature is 45 o C, and the dissolution time is 60min to obtain a sodium salt solution.

[0083] (2) 500 ml of Mn(NO3)2(0.02 M) was dissolved in ultrapure water, the stirring rate was 500 rpm, the dissolution temperature was 25 o C, and the dissolution time was 30 min to obtain a manganese salt solution;

[0084] (3) 500 ml of KOH (1 M) was dissolved in ultrapure water, the stirring rate was 600 rpm, the dissolution temperature was 25 o C, and the dissolution time was 40 min to obtain a strong alkali solution;

[0085] (4) The conductive substrate was electrochemically oxidized in the sodium salt solution described in step (1) by the I-t method, the oxidation temperature was 25 o C, the oxidation voltage was 2.5 V, the oxidation time was 1 min, and the material was washed and dried;

[0086] (5) The material obtained in step (4) was electrochemically deposited in the manganese salt solution described in step (2) by the I-t method, the deposition temperature was 80 o C, the deposition voltage was -1.5 V, the deposition time was 20 min, and the material was washed and dried;

[0087] (6) The material obtained in step (5) was electrochemically activated in the strong alkali solution described in step (3) by the CV method, the activation temperature was 25 o C, the activation voltage was 0-0.7 V, the activation time was 13 min, and the material was washed and dried to obtain a conductive substrate loaded manganese dioxide.

[0088] The preparation method of the zinc ion battery positive electrode sheet: since the manganese dioxide synthesized by the direct electrochemical method is on the conductive substrate, the positive electrode sheet with a diameter of 12 mm is directly pressed by a sheet puncher for standby.

[0089] The capacity performance graph of the zinc ion battery provided in the embodiment is shown in Figure 2 , the X-ray diffraction analysis graph of the positive electrode active material manganese dioxide provided in the embodiment is shown in Figure 3 , and the scanning electron microscope graph of the positive electrode active material manganese dioxide provided in the embodiment is shown in Figure 8 .

[0090] Embodiment 2

[0091] The embodiment provides a preparation method of a high-loading manganese dioxide electrode and a zinc ion battery positive electrode sheet:

[0092] The preparation method of the manganese dioxide comprises the following steps:

[0093] (1) 500 ml of NaSO4(1 M) was dissolved in ultrapure water, the stirring rate was 600 rpm, the dissolution temperature was 45 oC, the dissolving time is 60 min, and a sodium salt solution is obtained;

[0094] (2) 500 ml of Mn(NO3)2(0.02 M) is dissolved in ultrapure water, the stirring rate is 500 rpm, and the dissolving temperature is 25 o C, the dissolving time is 30 min, and a manganese salt solution is obtained;

[0095] (3) 500 ml of KOH (1 M) is dissolved in ultrapure water, the stirring rate is 600 rpm, and the dissolving temperature is 25 o C, the dissolving time is 40 min, and a strong alkali solution is obtained;

[0096] (4) The conductive substrate is electrochemically oxidized in the sodium salt solution described in step (1) by an I-t method, the oxidation temperature is 25 o C, the oxidation voltage is 2.5 V, the oxidation time is 1 min, and the material is washed and dried;

[0097] (5) The material obtained in step (4) is electrochemically deposited in the manganese salt solution described in step (2) by an I-t method, the deposition temperature is 80 o C, the deposition voltage is -1.5 V, the deposition time is 20 min, and the material is washed and dried;

[0098] (6) The material obtained in step (5) is electrochemically activated in the strong alkali solution described in step (3) by a CV method, the activation temperature is 60 o C, the activation voltage is 0-0.7 V, the activation time is 13 min, and the material is washed and dried to obtain a conductive substrate loaded manganese dioxide.

[0099] The preparation method of the zinc ion battery positive electrode sheet: since the manganese dioxide is directly synthesized on the conductive substrate by the electrochemical method, the positive electrode sheet with a diameter of 12 mm is directly pressed by a sheet puncher for standby.

[0100] The capacity performance graph of the zinc ion battery provided in the embodiment is as shown in Figure 2 The X-ray diffraction analysis graph of the positive electrode active material manganese dioxide provided in the embodiment is as shown in Figure 3

[0101] Embodiment 3

[0102] The embodiment provides a preparation method of a high-loading manganese dioxide electrode and a zinc ion battery positive electrode sheet:

[0103] The preparation method of the manganese dioxide comprises the following steps:

[0104] (1) 500 ml of NaSO4(1 M) is dissolved in ultrapure water, the stirring rate is 600 rpm, and the dissolving temperature is 45​o C, dissolution time is 60 min, to obtain a sodium salt solution;

[0105] (2) 500 ml of Mn(NO3)2(0.02 M) is dissolved in ultrapure water, the stirring rate is 500 rpm, the dissolution temperature is 25 o C, dissolution time is 30 min, to obtain a manganese salt solution;

[0106] (3) 500 ml of KOH (1 M) is dissolved in ultrapure water, the stirring rate is 600 rpm, the dissolution temperature is 25 o C, dissolution time is 40 min, to obtain a strong base solution;

[0107] (4) The conductive substrate is electrochemically oxidized in the sodium salt solution described in step (1) by the I-t method, the oxidation temperature is 25 o C, the oxidation voltage is 2.5 V, the oxidation time is 1 min, and the material is washed and dried;

[0108] (5) The material obtained in step (4) is electrochemically deposited in the manganese salt solution described in step (2) by the I-t method, the deposition temperature is 80 o C, the deposition voltage is -1.5 V, the deposition time is 20 min, and the material is washed and dried;

[0109] (6) The material obtained in step (5) is electrochemically activated in the strong base solution described in step (3) by the CV method, the activation temperature is 80 o C, the activation voltage is 0~0.7 V, the activation time is 13 min, and the material is washed and dried to obtain a conductive substrate loaded manganese dioxide.

[0110] The preparation method of the zinc ion battery positive electrode sheet: since the manganese dioxide is directly synthesized on the conductive substrate by the electrochemical method, the positive electrode sheet with a diameter of 12 mm is directly pressed by a sheet puncher for standby.

[0111] The scanning electron microscope image of the positive electrode active material manganese dioxide provided in the embodiment is shown in Figure 1 The capacity performance chart of the zinc ion battery provided in the embodiment is shown in Figure 2 The X-ray diffraction analysis chart of the positive electrode active material manganese dioxide provided in the embodiment is shown in Figure 3 The rate performance chart of the zinc ion battery in the embodiment is shown in Figure 4 The cycle performance chart of the zinc ion battery in the embodiment under a current density of 2.0 A / g is shown in Figure 5 The chart of the loadings of the positive electrode active material manganese dioxide provided in the embodiment changing with high-temperature electrodeposition time is shown in Figure 6 The capacity performance chart of the zinc ion battery in the embodiment under different current densities with different loadings is shown inFigure 7 as shown.

[0112] Example 4

[0113] The embodiment provides a preparation method of a high-loading manganese dioxide electrode and a zinc ion battery positive electrode sheet.

[0114] The preparation method of the manganese dioxide comprises the following steps:

[0115] (1) 500 ml of NaSO4 (1 M) is dissolved in ultrapure water, the stirring rate is 600 rpm, the dissolution temperature is 45 o C, and the dissolution time is 60 min to obtain a sodium salt solution;

[0116] (2) 500 ml of Mn(NO3)2 (0.02 M) is dissolved in ultrapure water, the stirring rate is 500 rpm, the dissolution temperature is 25 o C, and the dissolution time is 30 min to obtain a manganese salt solution;

[0117] (3) 500 ml of KOH (1 M) is dissolved in ultrapure water, the stirring rate is 600 rpm, the dissolution temperature is 25 o C, and the dissolution time is 40 min to obtain a strong alkali solution;

[0118] (4) The conductive substrate is electrochemically oxidized in the sodium salt solution in step (1) by an I-t method, the oxidation temperature is 25 o C, the oxidation voltage is 2.5 V, the oxidation time is 1 min, and the material is washed and dried;

[0119] (5) The material obtained in step (4) is electrochemically deposited in the manganese salt solution in step (2) by an I-t method, the deposition temperature is 80 o C, the deposition voltage is -1.5 V, the deposition time is 20 min, and the material is washed and dried;

[0120] (6) The material obtained in step (5) is electrochemically activated in the strong alkali solution in step (3) by a CV method, the activation temperature is 90 o C, the activation voltage is 0-0.7 V, the activation time is 13 min, and the material is washed and dried to obtain the conductive substrate loaded manganese dioxide.

[0121] The preparation method of the zinc ion battery positive electrode sheet: since the manganese dioxide is directly synthesized on the conductive substrate by the electrochemical method, the positive electrode sheet with a diameter of 12 mm is directly pressed by a sheet punching device for standby.

[0122] The capacity performance diagram of the zinc ion battery provided in the embodiment is as shown in Figure 2The X-ray diffraction analysis chart of the positive electrode active material manganese dioxide provided in the embodiment is shown in FIG. 1. Figure 3 As shown in FIG. 1.

[0123] Embodiment 5

[0124] The embodiment provides a preparation method of a high-loading manganese dioxide electrode and a zinc ion battery positive electrode sheet.

[0125] The preparation method of the manganese dioxide comprises the following steps:

[0126] (1) 500 ml of NaSO4 (1 M) is dissolved in ultrapure water, the stirring rate is 600 rpm, the dissolution temperature is 45 o C, and the dissolution time is 60 min to obtain a sodium salt solution;

[0127] (2) 500 ml of Mn(NO3)2 (0.02 M) is dissolved in ultrapure water, the stirring rate is 500 rpm, the dissolution temperature is 25 o C, and the dissolution time is 30 min to obtain a manganese salt solution;

[0128] (3) 500 ml of KOH (1 M) is dissolved in ultrapure water, the stirring rate is 600 rpm, the dissolution temperature is 25 o C, and the dissolution time is 40 min to obtain a strong alkali solution;

[0129] (4) The conductive substrate is electrochemically oxidized in the sodium salt solution in step (1) by an I-t method, the oxidation temperature is 25 o C, the oxidation voltage is 2.5 V, the oxidation time is 1 min, and the material is washed and dried;

[0130] (5) The material obtained in step (4) is electrochemically deposited in the manganese salt solution in step (2) by an I-t method, the deposition temperature is 25 o C, the deposition voltage is -1.5 V, the deposition time is 20 min, and the material is washed and dried;

[0131] (6) The material obtained in step (5) is electrochemically activated in the strong alkali solution in step (3) by a CV method, the activation temperature is 25 o C, the activation voltage is 0-0.7 V, the activation time is 13 min, and the material is washed and dried to obtain the conductive substrate loaded manganese dioxide.

[0132] The preparation method of the zinc ion battery positive electrode sheet: since the manganese dioxide is directly synthesized on the conductive substrate by the electrochemical method, the positive electrode sheet with a diameter of 12 mm is directly pressed by a sheet puncher for standby.

[0133] The capacity performance chart of the zinc ion battery provided in the embodiment is shown in FIG. 2.Figure 2 as shown.

[0134] Example 6

[0135] The embodiment provides a preparation method of a high-loading manganese dioxide electrode and a zinc ion battery positive electrode sheet.

[0136] The preparation method of the manganese dioxide comprises the following steps:

[0137] (1) 500 ml of NaSO4 (1 M) is dissolved in ultrapure water, the stirring rate is 600 rpm, the dissolution temperature is 45 o C, and the dissolution time is 60 min to obtain a sodium salt solution;

[0138] (2) 500 ml of Mn(NO3)2 (0.02 M) is dissolved in ultrapure water, the stirring rate is 500 rpm, the dissolution temperature is 25 o C, and the dissolution time is 30 min to obtain a manganese salt solution;

[0139] (3) 500 ml of KOH (1 M) is dissolved in ultrapure water, the stirring rate is 600 rpm, the dissolution temperature is 25 o C, and the dissolution time is 40 min to obtain a strong alkali solution;

[0140] (4) The conductive substrate is electrochemically oxidized in the sodium salt solution in step (1) by an I-t method, the oxidation temperature is 25 o C, the oxidation voltage is 2.5 V, the oxidation time is 1 min, and the material is washed and dried;

[0141] (5) The material obtained in step (4) is electrochemically deposited in the manganese salt solution in step (2) by an I-t method, the deposition temperature is 50 o C, the deposition voltage is -1.5 V, the deposition time is 15 min, and the material is washed and dried;

[0142] (6) The material obtained in step (5) is electrochemically activated in the strong alkali solution in step (3) by a CV method, the activation temperature is 25 o C, the activation voltage is 0-0.7 V, the activation time is 13 min, and the material is washed and dried to obtain the conductive substrate loaded manganese dioxide.

[0143] The preparation method of the zinc ion battery positive electrode sheet: since the manganese dioxide is directly synthesized on the conductive substrate by the electrochemical method, the positive electrode sheet with a diameter of 12 mm is directly pressed by a sheet puncher for standby.

[0144] The capacity performance diagram of the zinc ion battery provided in the embodiment is as shown in Figure 2 .

[0145] Example 7

[0146] The embodiment provides a preparation method of a high-loading manganese dioxide electrode and a zinc ion battery positive electrode sheet.

[0147] The preparation method of the manganese dioxide comprises the following steps:

[0148] (1) 500ml NaSO4 (1 M) is dissolved in ultrapure water, the stirring rate is 600rpm, the dissolution temperature is 45 o C, and the dissolution time is 60min to obtain a sodium salt solution;

[0149] (2) 500ml Mn(NO3)2 (0.02 M) is dissolved in ultrapure water, the stirring rate is 500rpm, the dissolution temperature is 25 o C, and the dissolution time is 30min to obtain a manganese salt solution;

[0150] (3) 500ml KOH (1 M) is dissolved in ultrapure water, the stirring rate is 600rpm, the dissolution temperature is 25 o C, and the dissolution time is 40min to obtain a strong alkali solution;

[0151] (4) the conductive substrate is electrochemically oxidized in the sodium salt solution in step (1) by an I-t method, the oxidation temperature is 25 o C, the oxidation voltage is 2.5V, the oxidation time is 1min, and the material is washed and dried;

[0152] (5) the material obtained in step (4) is electrochemically deposited in the manganese salt solution in step (2) by an I-t method, the deposition temperature is 0 o C, the deposition voltage is-1.5V, the deposition time is 60min, and the material is washed and dried;

[0153] (6) the material obtained in step (5) is electrochemically activated in the strong alkali solution in step (3) by a CV method, the activation temperature is 25 o C, the activation voltage is 0-0.7V, the activation time is 13min, and the conductive substrate loaded manganese dioxide is obtained by washing and drying.

[0154] The preparation method of the zinc ion battery positive electrode sheet: since the manganese dioxide is directly electrochemically deposited and synthesized on the conductive substrate, the positive electrode sheet with a diameter of 12mm is directly pressed by a sheet puncher for standby.

[0155] The capacity performance diagram of the zinc ion battery provided in the embodiment is as shown in Figure 2 .

[0156] In order to illustrate the related performance of the manganese dioxide provided by the present application, the related performance of the manganese dioxide provided by the present application is described with reference to the drawings.

[0157] Figure 1 Scanning electron microscope image of manganese dioxide prepared in Example 3. It can be seen from Figure 1 that the ultrathin manganese dioxide nanosheets are uniformly grown on the large piece, indicating that the conversion of manganese dioxide nanosheets after high-temperature restructuring is more sufficient.

[0158] Figure 2 Capacity performance graph of zinc ion battery in Examples 1-7. Among them, Figure 2 (a) is the mass specific capacity rate performance graph of zinc ion battery in Examples 1, 5-7 at different current densities; Figure 2 (b) is the area specific capacity rate performance graph of zinc ion battery in Examples 1-4 at different current densities.

[0159] It can be seen from Figure 2 (a) that compared with the manganese dioxide nanomaterials obtained in Examples 1, 6 and 7, the manganese dioxide nanomaterials obtained after low-temperature electrochemical deposition and low-temperature activation in Example 5 are more fully converted, so the mass specific capacity performance is higher; from Figure 2 (b) it can be seen that compared with the manganese dioxide nanomaterials obtained in Examples 1 and 2, the manganese dioxide nanomaterials obtained after high-temperature restructuring in Example 3 are more fully converted, so the area specific capacity performance is higher. By comparing the manganese dioxide nanomaterials obtained in Example 4, it can be confirmed that even if the temperature of the electrochemical activation process is increased again, the conversion degree of the manganese dioxide nanomaterials will not change more obviously, so the capacity performance will not be improved again.

[0160] Figure 3 X-ray diffraction analysis graph of manganese dioxide prepared in Examples 1-4. From Figure 3 it can be seen that compared with the manganese dioxide nanomaterials obtained in Examples 1 and 2, the manganese dioxide nanomaterials obtained after high-temperature restructuring in Example 3 are more fully converted. By comparing the manganese dioxide nanomaterials obtained in Example 4, it can be confirmed that even if the temperature of the electrochemical activation process is increased again, the conversion degree of the manganese dioxide nanomaterials will not be significantly improved.

[0161] Figure 4 Rate performance graph of zinc ion battery in Example 3. From Figure 4 it can be seen that at a current density of 0.1 A / g, a high specific capacity of about 330 mAh / g can be achieved, and excellent rate performance is achieved.

[0162] Figure 5 Cycle performance graph of zinc ion battery in Example 3 at a current density of 2.0 A / g. From 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.

[0163] Figure 6 The figure of the loading amount of manganese dioxide prepared in Example 3 changing with the high-temperature electrochemical deposition time. Figure 6 It can be seen that, under the condition of high-temperature electrochemical deposition, the loading amount of MnO2 active material gradually increases with the increase of deposition time, and the loading amount is conveniently improved.

[0164] Figure 7 The figure of the capacity performance of zinc ion batteries with different loading amounts under different current densities in Example 3. Figure 7 (a) is the figure of the mass specific capacity rate performance of zinc ion batteries with different loading amounts under different current densities in Example 3; Figure 7 (b) is the figure of the area specific capacity rate performance of zinc ion batteries with different loading amounts under different current densities in Example 3; Figure 7 (c) is the figure of the mass / area specific capacity performance of zinc ion batteries with different loading amounts under a current density of 0.2 mA / cm 2 in Example 3.

[0165] Figure 8 The scanning electron microscope figure of manganese dioxide prepared in Example 1. Figure 8 It can be seen from the figure that the material prepared in Example 1 retains part of the nanosheets with a larger size, indicating that it is not completely converted into manganese dioxide nanosheets.

[0166] The present application describes preferred embodiments and their effects. However, those skilled in the art can make further changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0167] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high loading manganese dioxide electrode, characterized by, The method comprises the following steps: electrochemically oxidizing the conductive substrate in a sodium salt solution; electrochemically depositing manganese dioxide on the conductive substrate in a manganese salt solution; electrochemically activating the conductive substrate in a strong alkali solution to obtain a conductive substrate loaded with manganese dioxide; The conductive substrate comprises 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 by, The sodium salt solution is prepared by uniformly dispersing sodium salt in an aqueous solvent, and the concentration of the sodium salt solution is 0.5-1.5 mol / L. The sodium salt comprises one or more of sodium chloride, sodium sulfate, sodium nitrate and sodium acetate.

3. The method of claim 1, wherein the manganese dioxide electrode is prepared by the steps of: The manganese salt solution is prepared by uniformly dispersing manganese salt in an aqueous solvent, and the concentration of the manganese salt solution is 0.01-0.03 mol / L. The manganese salt comprises one or more of manganese chloride, manganese sulfate, manganese nitrate and manganese acetate.

4. The method of claim 1, wherein the manganese dioxide electrode is prepared by the steps of: 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 comprises sodium hydroxide and / or potassium hydroxide.

5. The method of claim 1, wherein the high loading manganese dioxide electrode is prepared by the steps of: The temperature during the electrochemical oxidation is 0 to 85 o C, the oxidation time is 0.5 to 2.5 min, and the oxidation voltage is 1 to 3 V.

6. The method of claim 1, wherein the high loading manganese dioxide electrode is prepared by the steps of: The temperature during the electrochemical deposition is 20-85 o C, the deposition time is 5-25 min, and the deposition voltage is -2-1 V.

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 20-85 o C, the activation time is 10-20 min, and the activation voltage is -1-2 V.

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

9. Use of the high-loading manganese dioxide electrode of 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 of claim 8.

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