A method for preparing an aqueous zinc-ion battery cathode material

Abstract

This invention discloses a method for preparing an aqueous zinc-ion battery cathode material. The method includes: coating a conductive polymer onto the surface of a cathode active material via gas-phase polymerization or liquid-phase polymerization to obtain the aqueous zinc-ion battery cathode material; wherein the conductive polymer formed on the surface of the aqueous zinc-ion battery cathode material is ordered; the cathode active material is one or more of graphene, manganese-based oxides, vanadium-based oxides, vanadium-based nitrides, Prussian blue and its analogues, metal / covalent organic framework compounds, organic electrochemical materials, layered MXene, layered sulfides, and layered selenides. The aqueous zinc-ion battery cathode material prepared by this invention overcomes the dissolution problem of active materials in existing cathode materials, achieves efficient utilization of the cathode active material, enhances zinc ion storage, and thus improves the rate performance and cycle stability of the battery.

Description

Technical Field

[0001] This invention relates to the field of electrochemical energy storage devices, and more specifically, to a method for preparing an aqueous zinc-ion battery cathode material. Background Technology

[0002] Rechargeable batteries, as efficient energy storage devices, are widely used in mobile communications and electric vehicles. Currently, the most commercially available rechargeable battery is the lithium-ion battery; however, due to the high cost, low safety, and supply risks of lithium resources, it is not suitable for large-scale grid energy technologies. Compared to lithium-ion batteries, zinc-based ion batteries are a good alternative because they offer higher capacity (two-electron reaction), lower cost, and a more suitable redox potential (-0.762V vs. H / H). + Therefore, the development of rechargeable zinc-ion batteries has become an urgent and attractive task today.

[0003] Aqueous zinc-ion batteries, based on aqueous electrolytes, are considered one of the most promising energy storage technologies due to their high safety, low cost, and excellent electrochemical performance. However, the development of aqueous zinc-ion batteries is still in its early stages. The cathode material plays a crucial role in the research of zinc storage mechanisms and the construction of high-performance batteries. Common cathode materials include manganese-based oxides, vanadium-based oxides, vanadium-based nitrides, Prussian blue and its analogues, metal / covalent organic framework compounds, layered MXenes, layered sulfides, and selenides. However, all these cathode materials face the problem of easy dissolution of active materials, which leads to a reduction in zinc-ion storage and a decrease in the cycle stability of the battery system. Therefore, providing a structurally stable cathode material for aqueous zinc-ion batteries is a pressing issue that needs to be addressed. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing an aqueous zinc-ion battery cathode material.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a method for preparing an aqueous zinc-ion battery cathode material, the method comprising: coating a conductive polymer onto the surface of a cathode active material by gas-phase polymerization or liquid-phase polymerization to obtain an aqueous zinc-ion battery cathode material;

[0007] Among them, the conductive polymer formed on the surface of the positive electrode material of the aqueous zinc-ion battery is ordered;

[0008] The positive electrode active material is one or more of the following: graphene, manganese-based oxide, vanadium-based oxide, vanadium-based nitrogen oxide, Prussian blue and its analogues, metal / covalent organic framework compounds, organic electrochemical materials, layered MXene, layered sulfides and layered selenides.

[0009] It should be noted that, generally speaking, polymer growth is disordered, with polymers entangled and interpenetrating. However, the preparation method of this invention utilizes the two-dimensional and microcavity structure of the positive electrode active material itself to regulate the polymer polymerization process, resulting in directional and ordered polymer growth. That is, the polymer grows orderly layer by layer along the surface of the positive electrode active material and forms a coating. For example, when polypyrrole grows in a directional and orderly manner layer by layer along the surface of the positive electrode active material, the five-membered rings of the pyrrole monomer are connected and arranged sequentially and in an orderly manner (e.g., ...). Figure 1 (As shown). In addition, as is well known, the positive electrode materials of traditional aqueous zinc-ion batteries generally suffer from the problems of easy dissolution of active materials and low utilization rate. This invention has discovered that by using a one-step method to in-situ coat the surface of the active material with an ordered conductive polymer, the ordered framework structure of the conductive polymer can be used to improve the structural stability of the positive electrode active material, thereby enhancing zinc ion storage and improving the rate performance and cycle stability of the battery.

[0010] Preferably, the manganese-based oxides are mainly tetravalent, trivalent, and intermediate valence manganese oxides, depending on the valence state of manganese; more preferably, they are manganese dioxide, manganese tetroxide, and manganese trioxide. The general chemical formula of Prussian blue and its analogues is MFe(CN)6 (M = Fe, Co, Ni, Cu, Mn), such as CuFe(CN)6 (CuHCF), Zn3[Fe(CN)6]2 (ZnHCF), etc. The organic electrochemical materials include conductive polymers such as polypyrrole and polyaniline.

[0011] Furthermore, the conductive polymer includes one or more of polypyrrole, polythiophene, polyaniline, poly3,4-ethylenedioxythiophene, and poly3-hexylthiophene.

[0012] Furthermore, the gas-phase polymerization specifically includes the following steps:

[0013] A dispersion of positive electrode active material is formed, and optionally an oxidant and / or a conductive agent is added to the dispersion, which is then dried and placed in a sealed container containing gaseous conductive polymer monomers for in-situ polymerization.

[0014] The above preparation method may include an oxidant. Those skilled in the art know that some positive electrode active materials possess inherent oxidizing properties, depending on the type chosen. Therefore, those skilled in the art can add additional oxidants as needed or utilize only the inherent oxidizing properties of the positive electrode active material for in-situ polymerization. Furthermore, the above preparation method may also include a conductive agent. The conductive agent is commonly a carbon-based conductive agent. Those skilled in the art know how to select the most suitable conductive agents for aqueous zinc-ion batteries, such as conductive carbon black, acetylene black (AB), and 350G.

[0015] Furthermore, the concentration of the positive electrode active material in the dispersion is 0.01–15 mg / mL.

[0016] Furthermore, the amount of oxidant added is 0.0005–0.1 mol / L. This invention has found that the concentration of the oxidant and the concentration of the positive electrode active material affect the polymerization rate; only within a specific reaction rate range can the synthesized conductive polymer exhibit a higher degree of order. Therefore, regardless of whether the oxidizing property of the positive electrode active material itself is utilized, the amount of oxidant that can be added can only be optimally controlled within the range specified in this invention to regulate the degree of order of the conductive polymer.

[0017] According to a specific embodiment of the present invention, the drying includes, but is not limited to, heating drying, forced air drying, freeze drying and room temperature drying, and preferably, freeze drying.

[0018] Furthermore, the conditions for the in-situ polymerization reaction are as follows: the temperature of the in-situ polymerization reaction is -30 to 40°C, and the time of the in-situ polymerization reaction is 1 hour to 50 days. The temperature of the in-situ polymerization reaction is within the range of this invention, which can ensure that the conductive polymer monomer is in a gaseous state while controlling the rate of its in-situ polymerization reaction.

[0019] Furthermore, the oxidant includes one or more of ferric chloride, ammonium persulfate, aluminum chloride, molybdenum trichloride, ruthenium trichloride, peracetic acid, hydrogen peroxide, and potassium permanganate.

[0020] Furthermore, the liquid-phase polymerization specifically includes the following steps:

[0021] To form a dispersion of positive electrode active material, optionally an oxidant and / or a conductive agent are added to the dispersion, followed by the addition of a conductive polymer monomer, and an in-situ polymerization reaction is carried out.

[0022] Furthermore, the concentration of the positive electrode active material in the dispersion is 0.03–20 mg / mL.

[0023] Furthermore, the amount of oxidant added is 0.00001 to 0.005 mol / L.

[0024] Furthermore, the oxidant includes one or more of ferric chloride, ammonium persulfate, aluminum chloride, molybdenum trichloride, ruthenium trichloride, peracetic acid, hydrogen peroxide, and potassium permanganate.

[0025] Furthermore, the conditions for the in-situ polymerization reaction are: the temperature of the in-situ polymerization reaction is 0 to 25°C, and the time of the in-situ polymerization reaction is 0.5 hours to 50 days.

[0026] Among these methods, liquid-phase polymerization for preparing ordered conductive polymers is more difficult to control than gas-phase polymerization. This is because gaseous polymer monomers have wider dispersion, which is more conducive to slow, layer-by-layer growth, while liquid monomers polymerize much faster. Therefore, it is necessary to control every detail of the reaction process to successfully synthesize ordered conductive polymers. Consequently, if the conditions of liquid-phase polymerization are not within the scope of this invention, the resulting conductive polymer will have poor order, or even be completely disordered.

[0027] Furthermore, unless otherwise specified, any range described in this invention includes end values, any values ​​between end values, and any sub-ranges formed by end values ​​or any values ​​between end values. There are no particular limitations on the purity of any raw materials used in this invention; however, analytical grade is preferred. The sources and abbreviations of all raw materials used in this invention are conventional sources and abbreviations in the art, and are clearly defined within the scope of their relevant uses. Those skilled in the art can obtain them from commercially available sources or prepare them using conventional methods based on their abbreviations and corresponding uses. All percentages in this invention are by mass unless otherwise specified, and all solutions use water as the solvent unless otherwise specified.

[0028] The beneficial effects of this invention are as follows:

[0029] The cathode material prepared by the method provided by this invention overcomes the problem of easy solubility of active components in existing aqueous zinc-ion battery cathode materials, improves the structural stability of traditional aqueous zinc-ion battery cathode materials, realizes the efficient utilization of cathode materials, and thus improves the storage, rate performance and cycle stability of zinc ions in aqueous zinc-ion batteries.

[0030] The method for preparing aqueous zinc-ion battery cathode material provided by this invention uses inexpensive and readily available raw materials, has a simple process, is easy to operate, and is suitable for large-scale production applications. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0032] Figure 1 A schematic diagram of the molecular structure of ordered polypyrrole is shown.

[0033] Figure 2 The selected area electron diffraction pattern of the aqueous zinc-ion battery cathode material prepared in Example 1 is shown.

[0034] Figure 3 The diagram shows the cycle performance test results of the aqueous zinc-ion battery in Example 1.

[0035] Figure 4 The cycle performance test diagram of the aqueous zinc-ion battery in Comparative Example 1 is shown. Detailed Implementation

[0036] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further clarifies the invention. Similar components in the drawings are indicated by the same reference numerals. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0037] Example 1

[0038] 1) Preparation of an aqueous zinc-ion battery cathode material, comprising the following steps:

[0039] A graphene oxide aqueous dispersion (3 mg / mL) containing 0.005 M ferric chloride (FeCl3) was ultrasonically dispersed for 2 h to obtain a mixture. The mixture was then injected into a petri dish and frozen in a refrigerator (-70℃) for 2 h, followed by freeze-drying at -60℃ for 40 h to obtain graphene oxide foam (GOF). The prepared GOF was placed in a sealed container containing pyrrole monomer vapor, and pyrrole was polymerized in situ on the GOF (gas-phase polymerization) at 10℃ for 1.5 h. After removal, the GOF was reduced by hydrazine hydrate at 80℃ under vacuum to obtain the cathode material - ordered polypyrrole-coated graphene foam.

[0040] 2) Assemble an aqueous zinc-ion battery, including the following steps:

[0041] The negative electrode material is a zinc sheet, and the positive electrode material is the ordered polypyrrole-coated graphene foam prepared in this embodiment. First, the ordered polypyrrole-coated graphene foam is ground and then mixed into a slurry according to the mass ratio of positive electrode material / carbon black / PVDF = 70 / 20 / 10. This slurry is then coated onto graphite paper and dried to form the electrode. A GFF membrane is used as the separator, and the electrolyte is 2 mol / L zinc sulfate + 0.1 mol / L manganese sulfate, assembling an aqueous zinc-ion button battery.

[0042] 3) Performance Testing: The aqueous zinc-ion button battery of this embodiment was subjected to charge-discharge tests at 1–1.8V, and cyclically charged for 1200 cycles at a current density of 1A / g and room temperature. The capacity retention rate was 80% (results are shown in the figure). Figure 3 (As shown).

[0043] Depend on Figure 2 As can be seen, the selected area electron diffraction pattern of the ordered polypyrrole-coated graphene foam prepared in this example has obvious polycrystalline characteristics, thus demonstrating the orderliness of the polypyrrole chains.

[0044] Example 2

[0045] 1) Preparation of an aqueous zinc-ion battery cathode material, comprising the following steps:

[0046] After ultrasonic dispersion of MXene containing 0.00025M ammonium persulfate (0.034 mg / mL) for 2 h, an appropriate amount of aniline monomer (oxidant to monomer molar ratio of 2:1) was added at 16 °C. The mixture was then magnetically stirred for 1.5 h, collected, and frozen in a refrigerator (-70 °C) for 2 h. Subsequently, it was freeze-dried at -60 °C for 40 h to obtain the cathode material - ordered polyaniline-coated MXene.

[0047] 2) Assemble an aqueous zinc-ion battery, including the following steps:

[0048] The negative electrode material is zinc sheet, and the positive electrode material is MXene coated with ordered polyaniline. First, the ordered polyaniline-coated MXene is ground and then mixed into a slurry according to the mass ratio of positive electrode material / carbon black / PVDF = 70 / 20 / 10. This slurry is then coated onto graphite paper and dried to form the electrode. A GFF membrane is used as the separator, and the electrolyte is 2 mol / L zinc sulfate + 0.1 mol / L manganese sulfate. The resulting aqueous zinc-ion button cell is assembled.

[0049] 3) Performance test: The aqueous zinc-ion button battery of this embodiment was charged and discharged at 1 to 1.8V. After 1200 cycles at a current density of 1A / g and room temperature, the capacity retention rate was 82%.

[0050] Example 3

[0051] 1) Preparation of an aqueous zinc-ion battery cathode material, comprising the following steps:

[0052] A manganese dioxide aqueous dispersion containing 0.00001M potassium permanganate (0.034 mg / mL) was ultrasonically dispersed for 2 h. Then, an appropriate amount of thiophene monomer (oxidant to monomer molar ratio of 2:1) was added at 20℃. After magnetic stirring for 1.5 h, the solution was collected and frozen in a refrigerator (-70℃) for 2 h. Subsequently, it was freeze-dried at -60℃ for 40 h to obtain the positive electrode material - ordered polythiophene-coated manganese dioxide.

[0053] 2) Assemble an aqueous zinc-ion battery, including the following steps:

[0054] The negative electrode material is zinc sheet, and the positive electrode material is ordered polyaniline-coated manganese dioxide. First, the ordered polyaniline-coated manganese dioxide is ground and then mixed into a slurry according to the mass ratio of positive electrode material / carbon black / PVDF = 70 / 20 / 10. This slurry is then coated onto graphite paper and dried to form the electrode. A GFF membrane is used as the separator, and the electrolyte is 2 mol / L zinc sulfate + 0.1 mol / L manganese sulfate, assembling an aqueous zinc-ion button cell.

[0055] 3) Performance test: The aqueous zinc-ion button battery of this embodiment was charged and discharged at 1 to 1.8V. After 1200 cycles at a current density of 1A / g and room temperature, the capacity retention rate was 78%.

[0056] Example 4

[0057] 1) Preparation of an aqueous zinc-ion battery cathode material, comprising the following steps:

[0058] A graphene oxide aqueous dispersion (3 mg / mL) containing 0.0005 M ferric chloride (FeCl3) was ultrasonically dispersed for 2 h to obtain a mixture. This mixture was then injected into a petri dish and frozen at -70°C for 2 h, followed by freeze-drying at -60°C for 40 h to obtain graphene oxide foam (GOF). The prepared GOF was placed in a sealed container containing aniline monomer vapor. Aniline was in-situ polymerized on the GOF at 0°C for 3 h. Afterward, the GOF was removed and reduced under vacuum at 80°C with hydrazine hydrate to obtain the cathode material – ordered polyaniline-coated graphene foam.

[0059] 2) Assemble an aqueous zinc-ion battery, including the following steps:

[0060] The negative electrode material is a zinc sheet, and the positive electrode material is the ordered polyaniline-coated graphene foam prepared in this embodiment. First, the ordered polyaniline-coated graphene foam is ground and then mixed into a slurry according to the mass ratio of positive electrode material / carbon black / PVDF = 70 / 20 / 10. This slurry is then coated onto graphite paper and dried to form the electrode. A GFF separator is used, and the electrolyte is 2 mol / L zinc sulfate + 0.1 mol / L manganese sulfate, assembling an aqueous zinc-ion button battery.

[0061] 3) Performance test: The aqueous zinc-ion button battery of this embodiment was charged and discharged at 1 to 1.8V. After 1200 cycles at a current density of 1A / g and room temperature, the capacity retention rate was 79%.

[0062] Example 5

[0063] 1) Preparation of an aqueous zinc-ion battery cathode material, comprising the following steps:

[0064] An aqueous dispersion of MXene containing 0.00025M ammonium persulfate (0.034 mg / mL) was ultrasonically dispersed for 2 h, and then an appropriate amount of thiophene monomer (the molar ratio of oxidant to monomer was 2:1) was added. The mixture was then magnetically stirred at 15 °C for 1 h, the solution was collected, and the solution was frozen in a refrigerator (-70 °C) for 2 h. Subsequently, it was freeze-dried at -60 °C for 40 h to obtain the cathode material - ordered polythiophene-coated MXene.

[0065] 2) Assemble an aqueous zinc-ion battery, including the following steps:

[0066] The negative electrode material is zinc sheet, and the positive electrode material is MXene coated with ordered polythiophene. First, the ordered polythiophene-coated MXene is ground and then mixed into a slurry with a mass ratio of positive electrode material / carbon black / PVDF of 70 / 20 / 10. This slurry is then coated onto graphite paper and dried to form the electrode. A GFF membrane is used as the separator, and the electrolyte is 2 mol / L zinc sulfate + 0.1 mol / L manganese sulfate. The resulting aqueous zinc-ion button cell is assembled.

[0067] 3) Performance test: The aqueous zinc-ion button battery of this embodiment was charged and discharged at 1 to 1.8V. After 1200 cycles at a current density of 1A / g and room temperature, the capacity retention rate was 76%.

[0068] Example 6

[0069] 1) Preparation of an aqueous zinc-ion battery cathode material, comprising the following steps:

[0070] A manganese dioxide aqueous dispersion containing 0.00001M ammonium persulfate (0.034 mg / mL) was ultrasonically dispersed for 2 h, and then an appropriate amount of thiophene monomer (oxidant to monomer molar ratio of 2:1) was added. The mixture was then magnetically stirred at 15 °C for 1.5 h, the solution was collected, and then frozen in a refrigerator (-70 °C) for 2 h. Subsequently, it was freeze-dried at -60 °C for 40 h to obtain the positive electrode material - ordered polythiophene-coated manganese dioxide.

[0071] 2) Assemble an aqueous zinc-ion battery, including the following steps:

[0072] The negative electrode material is zinc sheet, and the positive electrode material is ordered polyaniline-coated manganese dioxide. First, the ordered polyaniline-coated manganese dioxide is ground and then mixed into a slurry according to the mass ratio of positive electrode material / carbon black / PVDF = 70 / 20 / 10. This slurry is then coated onto graphite paper and dried to form the electrode. A GFF membrane is used as the separator, and the electrolyte is 2 mol / L zinc sulfate + 0.1 mol / L manganese sulfate, assembling an aqueous zinc-ion button cell.

[0073] 3) Performance test: The aqueous zinc-ion button battery of this embodiment was charged and discharged at 1 to 1.8V. After 1200 cycles at a current density of 1A / g and room temperature, the capacity retention rate was 73%.

[0074] Example 7

[0075] 1) Preparation of an aqueous zinc-ion battery cathode material, comprising the following steps:

[0076] A graphene oxide aqueous dispersion (3 mg / mL) containing 0.0005 M ferric chloride was ultrasonically dispersed for 2 h to obtain a mixture. The mixture was then injected into a petri dish and frozen in a refrigerator (-70℃) for 2 h, followed by freeze-drying at -60℃ for 40 h to obtain graphene oxide foam (GOF). The prepared GOF was placed in a sealed container containing 3,4-ethylenedioxythiophene monomer vapor. 3,4-ethylenedioxythiophene was in-situ polymerized on the GOF (gas-phase polymerization) at 0℃ for 2 h. After removal, it was reduced by hydrazine hydrate at 80℃ under vacuum to obtain the cathode material - ordered poly(3,4-ethylenedioxythiophene) coated graphene foam.

[0077] 2) Assemble an aqueous zinc-ion battery, including the following steps:

[0078] The negative electrode material is a zinc sheet, and the positive electrode material is the ordered poly(3,4-ethylenedioxythiophene)-coated graphene foam prepared in this embodiment. First, the ordered poly(3,4-ethylenedioxythiophene)-coated graphene foam is ground and then mixed into a slurry according to the mass ratio of positive electrode material / carbon black / PVDF = 70 / 20 / 10. This slurry is then coated onto graphite paper and dried to form the electrode. A GFF membrane is used as the separator, and the electrolyte is 2 mol / L zinc sulfate + 0.1 mol / L manganese sulfate, assembling an aqueous zinc-ion button battery.

[0079] 3) Performance testing: The aqueous zinc-ion button battery of this embodiment was charged and discharged at 1 to 1.8V. After 1200 cycles at a current density of 1A / g and room temperature, the capacity retention rate was 81%.

[0080] Example 8

[0081] 1) Preparation of an aqueous zinc-ion battery cathode material, comprising the following steps:

[0082] An aqueous dispersion of oxidized MXene (5 mg / mL) containing 0.001 M ferric chloride was ultrasonically dispersed for 2 h to obtain a mixture. This mixture was then injected into a petri dish and frozen at -70°C for 2 h, followed by freeze-drying at -60°C for 40 h to obtain MXene foam. The prepared MXene foam was placed in a sealed container containing 3,4-ethylenedioxythiophene monomer vapor. At 0°C, 3,4-ethylenedioxythiophene was in-situ polymerized on the MXene foam (gas-phase polymerization) for 2 h. The foam was then removed to obtain the cathode material – ordered poly(3,4-ethylenedioxythiophene)-coated MXene foam.

[0083] 2) Assemble an aqueous zinc-ion battery, including the following steps:

[0084] The negative electrode material is a zinc sheet, and the positive electrode material is MXene foam coated with ordered poly(3,4-ethylenedioxythiophene) prepared in this embodiment. First, the ordered poly(3,4-ethylenedioxythiophene) coated MXene foam is ground and then mixed into a slurry according to the mass ratio of positive electrode material / carbon black / PVDF = 70 / 20 / 10. This slurry is then coated onto graphite paper and dried to form the electrode. A GFF membrane is used as the separator, and the electrolyte is 2 mol / L zinc sulfate + 0.1 mol / L manganese sulfate, assembling an aqueous zinc-ion button battery.

[0085] 3) Performance test: The aqueous zinc-ion button battery of this embodiment was charged and discharged at 1 to 1.8V. After 1200 cycles at a current density of 1A / g and room temperature, the capacity retention rate was 72%.

[0086] Example 9

[0087] 1) Preparation of an aqueous zinc-ion battery cathode material, comprising the following steps:

[0088] A manganese dioxide aqueous dispersion containing 0.00005M ammonium persulfate (0.1 mg / mL) was ultrasonically dispersed for 2 h, and then an appropriate amount of thiophene monomer (the molar ratio of oxidant to monomer was 2:1) was added. The mixture was then magnetically stirred at 15 °C for 1.5 h, the solution was collected, and the solution was frozen in a refrigerator (-70 °C) for 2 h. Subsequently, it was freeze-dried at -60 °C for 40 h to obtain the positive electrode material - ordered polythiophene-coated manganese dioxide.

[0089] 2) Assemble an aqueous zinc-ion battery, including the following steps:

[0090] The negative electrode material is zinc sheet, and the positive electrode material is ordered polyaniline-coated manganese dioxide. First, the ordered polyaniline-coated manganese dioxide is ground and then mixed into a slurry according to the mass ratio of positive electrode material / carbon black / PVDF = 70 / 20 / 10. This slurry is then coated onto graphite paper and dried to form the electrode. A GFF membrane is used as the separator, and the electrolyte is 2 mol / L zinc sulfate + 0.1 mol / L manganese sulfate, assembling an aqueous zinc-ion button cell.

[0091] 3) Performance test: The aqueous zinc-ion button battery of this embodiment was charged and discharged at 1 to 1.8V. After 1200 cycles at a current density of 1A / g and room temperature, the capacity retention rate was 70%.

[0092] Example 10

[0093] 1) Preparation of an aqueous zinc-ion battery cathode material, comprising the following steps:

[0094] An aqueous dispersion of MXene oxide containing 0.005 M ferric chloride (20 mg / mL) was ultrasonically dispersed for 2 h to obtain a mixture. This mixture was then injected into a petri dish and frozen at -70°C for 2 h, followed by freeze-drying at -60°C for 40 h to obtain MXene foam. The prepared MXene foam was placed in a sealed container containing 3,4-ethylenedioxythiophene monomer vapor. At 0°C, 3,4-ethylenedioxythiophene was in-situ polymerized on the MXene foam (gas-phase polymerization) for 1.5 h. The resulting material was an ordered poly(3,4-ethylenedioxythiophene)-coated MXene foam, which was then removed to obtain the cathode material.

[0095] 2) Assemble an aqueous zinc-ion battery, including the following steps:

[0096] The negative electrode material is a zinc sheet, and the positive electrode material is MXene foam coated with ordered poly(3,4-ethylenedioxythiophene) prepared in this embodiment. First, the ordered poly(3,4-ethylenedioxythiophene) coated MXene foam is ground and then mixed into a slurry according to the mass ratio of positive electrode material / carbon black / PVDF = 70 / 20 / 10. This slurry is then coated onto graphite paper and dried to form the electrode. A GFF membrane is used as the separator, and the electrolyte is 2 mol / L zinc sulfate + 0.1 mol / L manganese sulfate, assembling an aqueous zinc-ion button battery.

[0097] 3) Performance test: The aqueous zinc-ion button battery of this embodiment was charged and discharged at 1 to 1.8V. After 1200 cycles at a current density of 1A / g and room temperature, the capacity retention rate was 71%.

[0098] Comparative Example 1

[0099] 1) Preparation of an aqueous zinc-ion battery cathode material, comprising the following steps:

[0100] A graphene oxide aqueous dispersion (3 mg / mL) containing 0.1 M ferric chloride (FeCl3) was ultrasonically dispersed for 2 h, followed by the addition of 1 mL of pyrrole monomer. The dispersion was ultrasonically dispersed for 30 min, and after standing for 24 hours until the reaction was complete, the mixture was poured into a petri dish. The petri dish was frozen at -70°C for 2 hours, and then freeze-dried at -60°C for 40 h to obtain disordered polypyrrole-coated graphene oxide foam. Then, under vacuum, it was reduced by hydrazine hydrate at 80°C to obtain the cathode material – disordered polypyrrole-coated graphene foam.

[0101] 2) Assemble an aqueous zinc-ion battery, including the following steps:

[0102] The negative electrode material is a zinc sheet, and the positive electrode material is disordered polypyrrole-coated graphene foam prepared in this embodiment. First, the disordered polypyrrole-coated graphene foam is ground and then mixed into a slurry according to the mass ratio of positive electrode material / carbon black / PVDF = 70 / 20 / 10. This slurry is then coated onto graphite paper and dried to form the electrode. A GFF separator is used, and the electrolyte is 2 mol / L zinc sulfate + 0.1 mol / L manganese sulfate, assembling an aqueous zinc-ion button battery.

[0103] 3) Performance Testing: The aqueous zinc-ion button battery of this embodiment was subjected to charge-discharge tests at 1–1.8V, and cyclically charged for 1200 cycles at a current density of 1A / g and room temperature. The capacity retention rate was 41% (results are shown in the figure). Figure 4 (As shown).

[0104] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing an aqueous zinc-ion battery cathode material, characterized in that, The method includes: coating a conductive polymer onto the surface of a positive electrode active material by gas-phase polymerization or liquid-phase polymerization to obtain an aqueous zinc-ion battery positive electrode material; Among them, the conductive polymer formed on the surface of the positive electrode material of the aqueous zinc-ion battery is ordered; The positive electrode active material is one or more of the following: graphene oxide, manganese dioxide, layered MXene, layered sulfides, and layered selenides; The order refers to the orderly layer-by-layer growth of polymers along the surface of the positive electrode active material to form a coating; The conductive polymer includes one or more of polypyrrole, polythiophene, polyaniline, poly3,4-ethylenedioxythiophene, and poly3-hexylthiophene; The gas-phase polymerization specifically includes the following steps: A dispersion of positive electrode active material is formed, and optionally an oxidant and / or a conductive agent is added to the dispersion, dried, and then placed in a closed container containing gaseous conductive polymer monomers for in-situ polymerization reaction. The conditions for the in-situ polymerization reaction are: the temperature of the in-situ polymerization reaction is -30 ~ 40 ℃, and the time of the in-situ polymerization reaction is 1 hour to 50 days; The liquid-phase polymerization specifically includes the following steps: To form a dispersion of positive electrode active material, optionally an oxidant and / or a conductive agent are added to the dispersion, followed by the addition of a conductive polymer monomer, and an in-situ polymerization reaction is carried out. The conditions for the in-situ polymerization reaction are: the temperature of the in-situ polymerization reaction is 0~25 ℃, and the time of the in-situ polymerization reaction is 0.5 hours~50 days.

2. The preparation method according to claim 1, characterized in that, In the dispersion of the gas-phase polymerization, the concentration of the positive electrode active material is 0.01 ~ 15 mg / mL.

3. The preparation method according to claim 1, characterized in that, The amount of oxidant added in the gas-phase polymerization is 0.0005 ~ 0.1 mol / L.

4. The preparation method according to claim 1, characterized in that, The oxidant in the gas-phase polymerization includes one or more of ferric chloride, ammonium persulfate, aluminum chloride, molybdenum trichloride, ruthenium trichloride, peracetic acid, hydrogen peroxide, and potassium permanganate.

5. The preparation method according to claim 1, characterized in that, In the dispersion of the liquid-phase polymerization, the concentration of the positive electrode active material is 0.03 ~ 20 mg / mL.

6. The preparation method according to claim 1, characterized in that, The amount of oxidant added in the liquid-phase polymerization is 0.00001 ~ 0.005 mol / L.

7. The preparation method according to claim 1, characterized in that, The oxidant in the liquid-phase polymerization includes one or more of the following: ferric chloride, ammonium persulfate, aluminum chloride, molybdenum trichloride, ruthenium trichloride, peracetic acid, hydrogen peroxide, and potassium permanganate.

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