A positive electrode material for aqueous zinc ion batteries and a preparation method thereof

Abstract

The application discloses a kind of positive electrode material for aqueous zinc-ion battery and preparation method thereof, belong to chemical power supply technical field.The manganese source, cobalt source and precipitant urea are uniformly mixed in aqueous solution according to certain mass ratio, precursor is obtained after hydrothermal reaction, the precursor is calcined in air atmosphere at a specific temperature, and the bimetallic oxide MnCo2O4 is obtained after natural cooling.The positive electrode material has high adaptability with zinc electricity, has large surface area and rich pore structure, and can effectively adapt to zinc ion deintercalation.In addition, the synthesis method has the advantages of simple equipment required, low energy consumption, high material purity and excellent electrochemical performance of the material, and meets the requirements of low-cost green and environmental protection of the positive electrode material of aqueous zinc-ion battery.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of chemical power sources, and particularly relates to a positive electrode material for aqueous zinc ion batteries and a preparation method thereof. BACKGROUND

[0002] In recent years, lithium ion batteries have dominated the market of portable electronic products, but their inherent insecurity and high cost have led people to pay more attention to aqueous rechargeable batteries with high safety, stability and environmental friendliness. Among various choices, aqueous zinc ion batteries (AZIB) are an extremely attractive large-capacity energy storage power source, which has the following advantages. First, zinc resources are abundant and inexpensive. Second, zinc metal is generally stable in water and air, has a proper redox potential, and has a high theoretical specific capacity. Third, aqueous electrolytes have lower cost, higher safety and environmental friendliness, and can provide higher ionic conductivity than organic electrolytes. Manganese-based materials, vanadium-based materials, prussian blue analogs and other materials as positive electrode materials for zinc ion batteries have been widely studied, but various positive electrode materials have some limitations. Therefore, the development of positive electrode materials with high specific capacity, high rate performance and long cycle life is still one of the keys to the commercialization of aqueous zinc ion batteries.

[0003] Oxide materials with spinel structure have rich oxidation states, enhanced redox pairs and reversible zinc intercalation, so cobalt-based metal oxides (MCo2O4, M = Ni, Mn, Cu, Zn, etc.) with spinel structure have great application prospects. Among them, MnCo2O4 as a typical spinel cobalt-based metal oxide has attracted widespread attention and research in the field of electrochemical energy storage such as lithium ion batteries and supercapacitors due to its ultra-high theoretical specific capacity and excellent rate performance. Therefore, it is of great significance to research and develop MnCo2O4 as a positive electrode material for zinc ion batteries. SUMMARY

[0004] This section aims to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification to avoid obscuring the purpose of this section, abstract and title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0005] In view of the above and / or problems existing in the prior art, the present application is proposed.

[0006] Therefore, the purpose of the present application is to overcome the deficiencies in the prior art, and to provide a positive electrode material for aqueous zinc ion batteries, which is a pure phase MnCo2O4, a cubic phase belonging to the Fd3m space group, and has obvious advantages as a positive electrode material for aqueous zinc ion batteries.

[0007] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a cathode material for aqueous zinc-ion batteries.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solutions, including:

[0009] Manganese source, cobalt source and urea are dissolved in water to obtain a mixed solution. The mixed solution is subjected to hydrothermal reaction, washing and drying to obtain a precursor. The precursor is calcined to obtain MnCo2O4, the positive electrode material of aqueous zinc-ion battery.

[0010] The molar ratio of the manganese source to the cobalt source is 1:2, and the mass ratio of the sum of the manganese source and the cobalt source to urea is 1:0.25 to 2.

[0011] In a preferred embodiment of the method for preparing the positive electrode material for an aqueous zinc-ion battery according to the present invention, the manganese source includes one or more of manganese nitrate, manganese acetate, manganese chloride, and manganese sulfate; and the cobalt source includes one or more of cobalt nitrate, cobalt acetate, cobalt chloride, and cobalt sulfate.

[0012] As a preferred embodiment of the positive electrode material for aqueous zinc-ion batteries according to the present invention, the hydrothermal reaction is wherein the reaction temperature is 100-180°C and the reaction time is 5-20 hours.

[0013] As a preferred embodiment of the method for preparing the positive electrode material for aqueous zinc-ion batteries according to the present invention, the calcination is carried out in an air or oxygen atmosphere, wherein the heating rate is 1-10℃ / min, the sintering temperature is 400-700℃, and the sintering time is 2-6h.

[0014] As a preferred embodiment of the application of the cathode material described in this invention, wherein:

[0015] The positive electrode material MnCo2O4 is uniformly mixed with conductive carbon and binder, and water and ethanol are used as solvents to make a slurry. The slurry is coated on titanium foil, dried and pressed into a sheet to obtain the positive electrode sheet.

[0016] The positive electrode is applied to an aqueous zinc-ion battery.

[0017] In a preferred embodiment of the application of the positive electrode material described in this invention, the mass ratio of the positive electrode material, conductive carbon, and binder is 9-6:0.5-3:0.5-3.

[0018] In a preferred embodiment of the application of the positive electrode material described in this invention, the conductive carbon includes one or more of Super P, acetylene black, and carbon black.

[0019] In a preferred embodiment of the application of the cathode material described in this invention, the binder comprises one or more of polyvinylidene fluoride and sodium alginate.

[0020] As a preferred embodiment of the application of the cathode material described in this invention, the cathode material is highly compatible with aqueous zinc-ion batteries, and the aqueous zinc-ion battery obtained as the cathode material has excellent cycle performance and rate performance.

[0021] Beneficial effects of this invention:

[0022] (1) The present invention prepared a positive electrode material MnCo2O4 that is highly compatible with aqueous zinc-ion batteries. It was applied to zinc batteries for the first time and showed excellent cycle performance and rate performance.

[0023] (2) By optimizing the mass ratio of urea to precipitant, manganese and cobalt sources, hydrothermal reaction, and calcination temperature and time, this invention enables the material to achieve a higher compatibility with zinc batteries, effectively improving the conductivity and thermal stability of MnCo2O4, and obtaining a MnCo2O4 electrode material with superior zinc storage performance.

[0024] (3) The raw materials used in this invention are inexpensive, the equipment is simple, the energy consumption is low, the time is short, and the safety is high. The resulting MnCo2O4 material meets the requirements of high specific capacity, low cost, and green environmental protection for zinc-ion battery cathode materials. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0026] Figure 1 The image shows the XRD pattern of the MnCo2O4 material prepared in Example 1 of this invention.

[0027] Figure 2 This is a SEM image of the MnCo2O4 material prepared in Example 1 of the present invention.

[0028] Figure 3 The image shows the CV curve of the MnCo2O4 material prepared in Example 1 of this invention.

[0029] Figure 4 This is a cycle curve of the MnCo2O4 material prepared in Example 1 of the present invention.

[0030] Figure 5This is a rate performance diagram of the MnCo2O4 material prepared in Example 1 of the present invention.

[0031] Figure 6 This is a cycle curve of the Co3O4 material prepared in Comparative Example 1 of the present invention.

[0032] Figure 7 This is a cycle curve of the CoMn2O4 material prepared in Comparative Example 2 of this invention. Detailed Implementation

[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0034] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0035] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0036] Unless otherwise specified, all raw materials used in this invention are commercially available.

[0037] The materials prepared in the embodiments of the present invention were subjected to electrochemical performance testing according to the following method:

[0038] The positive electrode material synthesized by the method of the present invention, Super P and polyvinylidene fluoride are uniformly mixed at a mass ratio of 70:20:10, coated on titanium foil, dried in an 80°C forced-air oven for 8 hours, and then pressed into a 14 mm diameter disc to obtain the positive electrode sheet; using zinc metal as the counter electrode and a 2 mol / L ZnSO4 + 0.2 mol / L MnSO4 salt solution as the electrolyte, a coin cell is assembled.

[0039] Electrochemical performance was tested using a Shenzhen Xinwei BST-5V battery tester, with a charge / discharge voltage range of 0.8V to 1.9V (vs. Zn). 2+ / Zn), the test temperature is 25℃.

[0040] Example 1

[0041] This embodiment provides a method for preparing MnCo2O4 material, specifically as follows:

[0042] 0.75gMn(NO3)2·4H2O, 1.74gCo(NO3)2·6H2O and 1.25gCH4N2O were dissolved in 55mL of aqueous solution. After being magnetically stirred evenly at room temperature, the solution was transferred to a 100mL polytetrafluoroethylene liner and placed in a hydrothermal reactor for thermal reaction. The reaction was carried out at 150℃ in a forced-air oven for 10h. After cooling to room temperature, the precursor was obtained by washing and drying.

[0043] The precursor was heated to 500℃ in air at a rate of 5℃ / min for 3 hours, and then ground after natural cooling to obtain MnCo2O4 material.

[0044] Figure 1 The XRD pattern of MnCo2O4 prepared in Example 1 of this invention is shown in the figure. As can be seen from the figure, the main diffraction peaks are 31.1°, 36.5°, and 44.3°, which belong to the (220), (311), and (400) crystal planes in (PDF#23-1237), respectively. The prepared sample has no impurity peaks, indicating that the obtained MnCo2O4 material has high purity.

[0045] Figure 2 The image shows a SEM image of MnCo2O4 prepared in Example 1 of this invention. It can be seen that the morphology of MnCo2O4 prepared in this example is an irregular cube with porous layered stacking about 4-5 μm wide.

[0046] Figure 3 The cyclic voltammetry curve of MnCo2O4 prepared in Example 1 of this invention clearly shows two pairs of redox peaks. At the same time, the peak current of the redox peaks gradually increases from the first to the fifth scan, indicating that the electrode material is gradually activated during the initial electrochemical reaction.

[0047] Figure 4 The coin cell made of MnCo2O4 material prepared in Example 1 of this invention was tested at 800 mA g. -1 The electrochemical performance graph at current density shows that, after the first three rounds of activation with a small current of 0.05 A / g, the MnCo2O4 electrode in the example exhibits a discharge specific capacity of 156.8 mA hg. -1 Subsequently, after cycling at a low current of 0.8 A / g for 100 cycles, the specific capacity still remained as high as 182.2 mAh g. -1 .

[0048] Figure 5 The graph shows the rate performance curves of the coin cell prepared from MnCo2O4 obtained in Example 1 of this invention at different current densities. The prepared MnCo2O4 electrode material is shown at 100, 300, 500, 800, 1000, and 2000 mA g. -1When charged and discharged at current densities of [values ​​missing], the observed discharge specific capacities were 259.7, 230.1, 203.6, 187.1, 163.6, and 117.6 mA hg, respectively. -1 Even at 2000mA g -1 After cycling at high current density, when the current density recovers to 800 mA g -1 At that time, its discharge specific capacity remained at 177.4 mA hg -1 The level indicates that the MnCo2O4 prepared in this invention has good stability and excellent rate performance when used as the positive electrode of an aqueous zinc-ion battery.

[0049] Example 2

[0050] The difference between this embodiment and Embodiment 1 is that the temperature of the thermal reaction of the raw materials in the forced-air drying oven is adjusted to 180°C, while the rest of the preparation process is the same as in Embodiment 1, and MnCo2O4 material is obtained.

[0051] Example 3

[0052] The difference between this embodiment and Example 1 is that the temperature of the thermal reaction of the raw materials in the forced-air drying oven is adjusted to 100°C, while the rest of the preparation process is the same as in Example 1, and MnCo2O4 material is obtained.

[0053] The electrochemical performance of the materials prepared in the above embodiments was tested, and the results compared with those of Example 1 are shown in Table 1.

[0054] Table 1. Effect of different heat treatment temperatures on the properties of the prepared materials

[0055] <![CDATA[2Ag -1 Ratio performance 0.8 Ag -1 specific capacity after 100 cycles]]> Example 1 117.6 (mAhg -1 )]]> 182.2 (mAhg -1 ) Example 2 105.3 (mAhg -1 )]]> 179.3 (mAhg -1 )]]> Example 3 108.6 (mAhg -1 )]]> 178.9 (mAhg -1 ​

[0056] As can be seen from Table 1, adjusting the thermal reaction temperature of the raw materials has a significant impact on the performance of the cathode material. This is because the thermal reaction temperature affects the microstructure of the material, which in turn affects the specific surface area of ​​the material. The morphology and specific surface area of ​​the material can significantly affect its battery performance as an electrode material. According to the results in Table 1, the best technical effect can be obtained when the thermal reaction temperature in this invention is 150℃.

[0057] Example 4

[0058] The difference between this embodiment and Example 1 is that the calcination temperature of the precursor is adjusted to 400°C, while the rest of the preparation process is the same as in Example 1, and MnCo2O4 material is obtained.

[0059] Example 5

[0060] The difference between this embodiment and Example 1 is that the calcination temperature of the precursor is adjusted to 700°C, while the rest of the preparation process is the same as in Example 1, and MnCo2O4 material is obtained.

[0061] Example 6

[0062] The difference between this embodiment and Example 1 is that the heating rate of the precursor calcination is adjusted to 10℃ / min, while the rest of the preparation process is the same as in Example 1, and MnCo2O4 material is obtained.

[0063] Example 7

[0064] The difference between this embodiment and Example 1 is that the heating rate of the precursor calcination is adjusted to 2℃ / min, while the rest of the preparation process is the same as in Example 1, and MnCo2O4 material is obtained.

[0065] Example 8

[0066] The difference between this embodiment and Example 1 is that the calcination time of the precursor is adjusted to 6 hours, while the rest of the preparation process is the same as in Example 1, and MnCo2O4 material is obtained.

[0067] Example 9

[0068] The difference between this embodiment and Example 1 is that the calcination time of the precursor is adjusted to 2 hours, while the rest of the preparation process is the same as in Example 1, and MnCo2O4 material is obtained.

[0069] The electrochemical performance of the materials prepared in the above embodiments was tested, and the results compared with those of Example 1 are shown in Table 2.

[0070] Table 2 Effect of different calcination temperatures on the properties of the prepared materials

[0071] <![CDATA[2Ag -1 Ratio performance 0.8 Ag -1 specific capacity after 100 cycles Example 1 117.6 (mAhg -1 )]]> 182.2 (mAhg -1 )]]> Example 4 112.0 (mAhg -1 )]]> 180.9 (mAhg -1 )]]> Example 5 109.6 (mAhg -1 )]]> 176.6 (mAhg -1 )]]> Example 6 105.3 (mAhg -1 )]]> 175.1 (mAhg -1 )]]> Example 7 114.1 (mAhg -1 )]]> 181.5 (mAhg -1 )]]> Example 8 110.3 (mAhg -1 )]]> 180.9 (mAhg -1 )]]> Example 9 106.5 (mAhg -1 )]]> 177.5 (mAhg -1 )]]>

[0072] As can be seen from Table 2, adjusting the calcination conditions of the raw materials has a significant impact on the performance of the cathode material. This is because different calcination conditions affect the crystal structure of the material, and thus affect the material's function as a cathode material for zinc batteries. Excessively high or low calcination temperature, increased or decreased heating rate, and excessively long or short calcination time will all lead to a decrease in battery performance. In summary, the preferred calcination conditions are to heat to 500℃ at a rate of 5℃ / min and calcinate for 3 hours.

[0073] Example 10

[0074] The difference between this embodiment and Example 1 is that the manganese source and cobalt source are adjusted to MnSO4·4H2O and CoSO4·7H2O, respectively. All other preparation processes are the same as in Example 1. Specifically:

[0075] 0.67g MnSO4·4H2O, 1.69g CoSO4·7H2O and 1.25g CH4N2O were dissolved in 55mL of aqueous solution. After being magnetically stirred evenly at room temperature, the solution was transferred to a 100mL polytetrafluoroethylene liner and placed in a hydrothermal reactor for thermal reaction. The reaction was carried out at 150℃ for 10h in a forced-air oven. After cooling to room temperature, the precursor was obtained by washing and drying.

[0076] The precursor was heated to 500℃ in air at a rate of 5℃ / min for 3 hours, and then ground after natural cooling to obtain MnCo2O4 material.

[0077] Example 11

[0078] The difference between this embodiment and Example 1 is that the manganese source and cobalt source are adjusted to (CH3COO)2Mn·4H2O and (CH3COO)2Co·4H2O, respectively. The remaining preparation processes are the same as in Example 1.

[0079] 0.73g Mn(AC3)2·4H2O, 1.49g Co(AC3)2·4H2O and 1.25g CH4N2O were dissolved in 55mL of aqueous solution. After being magnetically stirred evenly at room temperature, the solution was transferred to a 100mL polytetrafluoroethylene liner and placed in a hydrothermal reactor for thermal reaction. The reaction was carried out at 150℃ for 10h in a forced-air oven. After cooling to room temperature, the precursor was obtained by washing and drying.

[0080] The precursor was heated to 500℃ in air at a rate of 5℃ / min for 3 hours, and then ground after natural cooling to obtain MnCo2O4 material.

[0081] Example 12

[0082] The difference between this embodiment and Example 1 is that the manganese and cobalt sources are adjusted to MnCl2·4H2O and CoCl2·6H2O, respectively. All other preparation processes are the same as in Example 1.

[0083] 0.59g MnCl2·4H2O, 1.43g CoCl2·6H2O and 1.25g CH4N2O were dissolved in 55mL of aqueous solution. After being magnetically stirred evenly at room temperature, the solution was transferred to a 100mL polytetrafluoroethylene liner and placed in a hydrothermal reactor for thermal reaction. The reaction was carried out at 150℃ in a forced-air oven for 10h. After cooling to room temperature, the precursor was obtained by washing and drying.

[0084] The precursor was heated to 500℃ in air at a rate of 5℃ / min for 3 hours, and then ground after natural cooling to obtain MnCo2O4 material.

[0085] Example 13

[0086] The difference between this embodiment and Example 1 is that the mass ratio of manganese source and cobalt source to precipitant urea is adjusted; the rest of the preparation process is the same as in Example 1. Specifically:

[0087] 0.75gMn(NO3)2·4H2O, 1.74gCo(NO3)2·6H2O and 2.5gCH4N2O were dissolved in 55mL of aqueous solution. After being magnetically stirred evenly at room temperature, the solution was transferred to a 100mL polytetrafluoroethylene liner and placed in a hydrothermal reactor for thermal reaction. The reaction was carried out at 150℃ in a forced-air oven for 10h. After cooling to room temperature, the precursor was obtained by washing and drying.

[0088] The precursor was heated to 500℃ in air at a rate of 5℃ / min for 3 hours, and then ground after natural cooling to obtain MnCo2O4 material.

[0089] Example 14

[0090] The difference between this embodiment and Example 1 is that the mass ratio of manganese source and cobalt source to precipitant urea is adjusted; the rest of the preparation process is the same as in Example 1. Specifically:

[0091] 0.75g Mn(NO3)2·4H2O, 1.74g Co(NO3)2·6H2O and 0.625g CH4N2O were dissolved in 55mL of aqueous solution. After being magnetically stirred evenly at room temperature, the solution was transferred to a 100mL polytetrafluoroethylene liner and placed in a hydrothermal reactor for thermal reaction. The reaction was carried out at 150℃ in a forced-air oven for 10h. After cooling to room temperature, the precursor was obtained by washing and drying.

[0092] The precursor was heated to 500℃ in air at a rate of 5℃ / min for 3 hours, and then ground after natural cooling to obtain MnCo2O4 material.

[0093] The electrochemical performance of the materials prepared in the above embodiments was tested, and the results compared with those of Example 1 are shown in Table 3.

[0094] Table 3. Effects of different raw materials and proportions on material properties

[0095] <![CDATA[2Ag -1 Ratio performance 0.8 Ag -1 specific capacity after 100 cycles Example 1 117.6 (mAhg -1 ) 182.2 (mAhg -1 )]]> Example 10 106.4 (mAhg -1 )]]> 178.6 (mAhg -1 )]]> Example 11 112.9 (mAhg -1 ) 179.0 (mAhg -1 ) Example 12 96.3 (mAhg -1 )]]> 165.2 (mAhg -1 ) Example 13 109.6 (mAhg -1 ) 177.9 (mAhg -1 )]]> Example 14 113.6 (mAhg -1 )]]> 180.2 (mAhg -1 )]]>

[0096] As can be seen from Table 3, adjusting the type of raw material and its ratio with urea has a significant impact on the performance of the cathode material. This is because different types of raw materials and their ratio with urea affect the pore size distribution of the material. A rich pore structure is conducive to the rapid transfer of electrons and ions, thereby improving battery performance. In summary, the optimal types of raw materials selected in this invention are Mn(NO3)2·4H2O and 1.74gCo(NO3)2·6H2O, and the optimal ratio of raw materials to urea is 1:0.5.

[0097] Comparative Example 1

[0098] This comparative example provides a method for preparing Co3O4 material, specifically as follows:

[0099] 2.5g Co(NO3)2·6H2O and 1.25g CH4N2O were dissolved in 55mL of aqueous solution. After being magnetically stirred evenly at room temperature, the solution was transferred to a 100mL polytetrafluoroethylene liner and placed in a hydrothermal reactor for thermal reaction. The reaction was carried out at 150℃ in a forced-air oven for 10h. After cooling to room temperature, the precursor was obtained by washing and drying.

[0100] The precursor was heated to 500℃ in air at a rate of 5℃ / min for 2 hours, and then ground after natural cooling to obtain the Co3O4 material.

[0101] Figure 6 For Comparative Example 1 of this invention, a coin cell made of Co3O4 material was prepared at 800 mA g. -1 The electrochemical performance graph at current density shows that after 97 cycles at a low current of 0.8 A / g, the specific capacity is only 83.5 mA hg. -1 .

[0102] Comparative Example 2

[0103] This comparative example provides a method for preparing CoMn2O4 material, specifically as follows:

[0104] 1.5g Mn(NO3)2·4H2O, 0.87g Co(NO3)2·6H2O and 1.25g CH4N2O were dissolved in 55mL of aqueous solution. After being magnetically stirred evenly at room temperature, the solution was transferred to a 100mL polytetrafluoroethylene liner and placed in a hydrothermal reactor for thermal reaction. The reaction was carried out at 150℃ for 10h in a forced-air oven. After cooling to room temperature, the precursor was obtained by washing and drying.

[0105] The precursor was heated to 500℃ in air at a rate of 5℃ / min for 2 hours, and then ground after natural cooling to obtain CoMn2O4 material.

[0106] Figure 7 Comparative Example 2 of this invention yielded a coin cell made of CoMn2O4 material at 800 mA g. -1 The electrochemical performance at current density shows a specific capacity of 155.7 mA hg after 97 cycles at a low current of 0.8 A / g. -1 Therefore, it can be seen that the MnCo2O4 electrode has excellent zinc storage performance and excellent cycling stability.

[0107] Table 4 compares the electrochemical performance of the cathode materials prepared in Example 1, Comparative Examples 1 and 2 of this invention.

[0108] Table 4 Performance of different materials as cathode materials in aqueous zinc-ion batteries

[0109] <![CDATA[2Ag -1 Ratio performance 0.8 Ag -1 specific capacity after 100 cycles Example 1 117.6 (mAhg -1 ) 182.2 (mAhg -1 ) Comparative Example 1 43.6 (mAhg -1 ) 83.58 (mAhg -1 )]]> Comparative Example 2 85.3 (mAhg -1 )]]> 155.7 (mAhg -1 )]]>

[0110] As shown in Table 4, compared with the two cathode materials Co3O4 and CoMn2O4, the MnCo2O4 prepared in this invention exhibits better rate capability and cycle performance when applied as the cathode material in aqueous zinc-ion batteries. This is attributed to the material's large specific surface area and abundant porous structure, which provides numerous redox reaction active sites. Furthermore, the synergistic effect of the multivalent dual ions in the bimetallic oxide enhances its conductivity. Therefore, the MnCo2O4 electrode possesses excellent zinc storage performance and cycle stability.

[0111] Comparative Example 3

[0112] This comparative example describes the preparation of MnCo2O4 materials via a low-temperature solid-state reaction method using glucose. Specifically:

[0113] Weigh 11.64g of Co(NO3)2·6H2O and 4.9g of Mn(AC3)2·4H2O and grind them in a mortar. Add glucose with a molar mass of 0.6 metal ions and continue grinding. The mixture becomes thinner and a strong acetic acid odor is released. Grind for a total of 25 minutes. After drying the ground product, calcine it in air at a rate of 5℃ / min from room temperature to 700℃ for 4 hours to obtain the MnCo2O4 material prepared by the low-temperature solid-state method.

[0114] Comparative Example 4

[0115] This comparative example prepared MnCo2O4 material via the sol-gel method, specifically as follows:

[0116] 11.64 g of Co(NO3)2·6H2O and 4.9 g of Mn(AC3)2·4H2O were weighed and dissolved in deionized water to obtain a metal ion solution. Glucose with a molar mass of 0.8 metal ions was weighed and dissolved in deionized water. The solution was stirred to obtain a glucose solution. The mixture was then aged at 70°C for 3 hours to form a wine-red transparent sol. The sol was dried to obtain a gray precursor powder. The powder was then calcined in air at a rate of 5°C / min from room temperature to 700°C for 6 hours to obtain the MnCo2O4 material prepared by the sol-gel method.

[0117] Comparative Example 5

[0118] The comparative example of preparing MnCo2O4 material via the auto-ignition method is as follows:

[0119] Weigh 11.64g of Co(NO3)2·6H2O and 4.9g of Mn(AC3)2·4H2O, grind them separately for 5min, mix them and continue grinding for 25min to obtain a viscous intermediate product. Place it in an oven at 160℃ for 12h, and the combustion reaction will give a gray powder. The powder will be calcined in air at a rate of 5℃ / min from room temperature to 500℃, and calcined at a constant temperature for 4h. Then, it will be allowed to cool naturally to room temperature to obtain the MnCo2O4 material prepared by the auto-ignition method.

[0120] Table 5 compares the electrochemical performance of the cathode materials prepared in Example 1, Comparative Examples 3, 4 and 5 of this invention.

[0121] Table 5 Performance of different materials as cathode materials in aqueous zinc-ion batteries

[0122] <![CDATA[2Ag -1 Ratio performance 0.8 Ag -1 specific capacity after 100 cycles]]> Example 1 117.6 (mAhg -1 )]]> 182.2 (mAhg -1 )]]> Comparative Example 3 62.2 (mAhg -1 )]]> 111.8 (mAhg -1 ) Comparative Example 4 65.7 (mAhg -1 )]]> 115.0 (mAhg -1 )]]> Comparative Example 5 57.1 (mAhg -1 )]]> 109.3 (mAhg -1 )]]>

[0123] The materials prepared in Comparative Examples 3-5 are MnCo2O4 materials used in catalysts or lithium-ion batteries in the prior art. As can be seen from Table 5, compared with the MnCo2O4 cathode material prepared in this invention, the materials in Comparative Examples 3-5 have poor compatibility with zinc batteries and do not have any advantages in application to zinc batteries compared with existing zinc battery materials.

[0124] In summary, this invention has prepared a cathode material highly compatible with aqueous zinc-ion batteries. It possesses a porous, layered, irregular cubic morphology, exhibiting a large specific surface area and a richer pore structure, effectively improving the zinc-ion transport rate. Furthermore, as a spinel-structured oxide material, it has abundant oxidation states and a reversible zinc intercalation structure, effectively enhancing the zinc-ion insertion / extraction efficiency. Moreover, as a bimetallic oxide, it possesses more redox reaction active sites, effectively mitigating the inherent low conductivity of monometallic oxides.

[0125] This invention is the first to apply MnCo2O4 to an aqueous zinc-ion battery, where Zn is present in the zinc-ion battery. 2+ As a divalent ion, it has a relatively large atomic mass and a greater electrostatic interaction with the crystal structure of the cathode material. The present invention optimizes the preparation process of MnCo2O4, and the resulting material can effectively perform zinc ion deintercalation / intercalation. Furthermore, through the synergistic effect between the two metal oxides, it has better zinc storage performance than previous materials.

[0126] The raw materials used in this invention are inexpensive, the equipment is simple, the energy consumption is low, the time is short, and the safety is high. The resulting MnCo2O4 material meets the requirements of high specific capacity, low cost, and green environmental protection for zinc-ion battery cathode materials.

[0127] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A positive electrode material for aqueous zinc-ion batteries, characterized in that: The material is pure phase MnCo2O4, cubic phase, belonging to space group Fd3m; The preparation method of the cathode material is as follows: manganese source, cobalt source and urea are dissolved in water to obtain a mixed solution. The mixed solution is subjected to hydrothermal reaction, washing and drying to obtain a precursor. The precursor is calcined to obtain the aqueous zinc-ion battery cathode material MnCo2O4. Wherein, the molar ratio of the manganese source to the cobalt source is 1:2, the mass ratio of the sum of the manganese source and the cobalt source to urea is 1:0.25~2, the manganese source is manganese nitrate, and the cobalt source is cobalt nitrate; The hydrothermal reaction is carried out at a temperature of 150°C for 5 to 20 hours. The calcination is carried out in an air or oxygen atmosphere, wherein the heating rate is 5℃ / min, the sintering temperature is 500℃, and the sintering time is 3h.

2. The application of the positive electrode material of the aqueous zinc-ion battery as described in claim 1, characterized in that: include, The positive electrode material MnCo2O4 is uniformly mixed with conductive carbon and binder, and water and ethanol are used as solvents to make a slurry. The slurry is coated on titanium foil, dried and pressed into a sheet to obtain the positive electrode sheet. The positive electrode is applied to an aqueous zinc-ion battery.

3. The application of the positive electrode material of the aqueous zinc-ion battery as described in claim 2, characterized in that: The mass ratio of the positive electrode material, conductive carbon, and binder is 9~6:0.5~3:0.5~3.

4. The application of the positive electrode material of the aqueous zinc-ion battery as described in claim 2, characterized in that: The conductive carbon includes one or more of Super P and acetylene black.

5. The application of the positive electrode material of the aqueous zinc-ion battery as described in claim 2, characterized in that: The adhesive includes one or more of polyvinylidene fluoride and sodium alginate.

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