A composite positive electrode material and its preparation method and application

Abstract

The present invention relates to the field of battery technology, and more specifically, to a composite positive electrode material, a preparation method thereof, and an application thereof. The composite positive electrode material comprises carbon nanotubes and amorphous manganese-based oxide nanoparticles located on the surface of the carbon nanotubes, wherein the amorphous manganese-based oxide nanoparticles have the general chemical formula (NiO) x (MnO) y , 0.25≤x≤0.75, 0.25≤y≤0.75, and x+y=1. The composite positive electrode material of the present invention has amorphous manganese-based oxide uniformly coated on the surface of carbon nanotubes, and has excellent cycle life and discharge specific capacity.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a composite positive electrode material and a preparation method and application thereof. Background Art

[0002] At present, the development of renewable energy represented by solar energy and wind energy is of vital importance to scientific development. However, the intermittent and geographical limitations of renewable energy make it impossible for them to completely replace traditional fossil fuels. These problems have promoted the rapid development of new energy storage technologies. Lithium-ion batteries (LIBs) occupy most of the energy storage market due to their excellent electrochemical performance. However, problems such as the high price and flammability of organic electrolytes and the increasing shortage of lithium resources have restricted their further development. In recent years, aqueous zinc-ion batteries (ZIBs) have attracted much attention in the field of energy storage due to their inherent advantages. The zinc negative electrode used in ZIBs has a high theoretical capacity (820mAh·g -1 ), a low redox potential (-0.763V vs. SHE), and abundant reserves. Furthermore, aqueous electrolytes have higher ionic conductivity than organic electrolytes and are cheaper and safer. Therefore, ZIBs are considered to have great potential for development and application in next-generation large-scale energy storage devices.

[0003] The cathode material plays a vital role in the electrochemical performance of ZIBs. To date, the cathode materials that have been widely reported mainly include vanadium-based materials, manganese-based materials and Prussian blue analogs. Among them, manganese-based materials have received widespread attention due to their unique advantages. First, manganese (Mn) has multiple valence states (Mn 2+ 、Mn 3 +、Mn 4+ 、Mn 7+ ), resulting in manganese-based compounds exhibiting significant atomic structural diversity and multiple valence phases. Furthermore, manganese reserves are abundant and inexpensive. Furthermore, manganese-based compounds are safe, non-toxic, and environmentally friendly. Therefore, manganese-based compounds have become one of the most promising candidates for zinc-ion battery cathodes.

[0004] Although manganese-based cathode materials have good performance, some key issues limit the further development of manganese-based materials. First, the solubility and disproportionation reaction of manganese-based materials make them unstable in aqueous solution, which leads to their poor cycle stability. 2+ The high charge density and Zn 2+ The strong electrostatic interaction with [MnO6] leads to slow ion insertion and diffusion kinetics. In addition, the inherent low conductivity of manganese-based materials leads to insufficient charge transfer kinetics, which in turn reduces their coulombic efficiency and rate performance.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] One object of the present invention is to provide a composite positive electrode material to overcome the shortcomings of the above-mentioned manganese-based positive electrode materials and have excellent cycle life and discharge specific capacity.

[0007] Another object of the present invention is to provide a method for preparing the composite positive electrode material, which is simple, environmentally friendly, and has mild and controllable conditions.

[0008] Another object of the present invention is to provide a positive electrode sheet.

[0009] Another object of the present invention is to provide a battery as described above.

[0010] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0011] A composite positive electrode material comprises carbon nanotubes and amorphous manganese-based oxide nanoparticles located on the surface of the carbon nanotubes, wherein the chemical formula of the amorphous manganese-based oxide nanoparticles is (NiO) x (MnO) y , 0.25≤x≤0.75, 0.25≤y≤0.75, and x+y=1.

[0012] In some embodiments, the amorphous manganese-based oxide nanoparticles include (NiO) 0.5 (MnO) 0.5 、(NiO) 0.75 (MnO) 0.25 and (NiO) 0.25 (MnO) 0.75 At least one of .

[0013] In some embodiments, the average particle size of the amorphous manganese-based oxide nanoparticles is 6 to 12 nm.

[0014] In some embodiments, the mass content of the amorphous manganese-based oxide nanoparticles in the composite positive electrode material is 70% to 90%.

[0015] A method for preparing a composite positive electrode material comprises the following steps:

[0016] A first mixed system of a manganese source, a nickel source, an organic solvent and a chelating agent is mixed with carbon nanotubes to obtain a second mixed system. The second mixed system is subjected to microwave heat treatment, solid-liquid separation is performed, and solids are collected and calcined.

[0017] In some embodiments, the manganese source includes manganese acetate and / or manganese acetylacetonate.

[0018] In some embodiments, the nickel source includes nickel acetate and / or nickel acetylacetonate.

[0019] In some embodiments, the organic solvent comprises benzyl alcohol.

[0020] In some embodiments, the chelating agent comprises 1,3-propylene glycol.

[0021] In some embodiments, the molar ratio of the manganese source to the nickel source is (0.5-2):1.

[0022] In some embodiments, in the first mixed system, the concentration of the manganese source is 50 to 150 mmol / L, and the concentration of the nickel source is 50 to 150 mmol / L.

[0023] In some embodiments, the volume ratio of the organic solvent to the chelating agent is (4-19):1.

[0024] In some embodiments, the method for preparing the first mixed system specifically includes: mixing a manganese source, a nickel source, an organic solvent, and a chelating agent and stirring for 10 to 20 minutes.

[0025] In some embodiments, in the second mixed system, the concentration of the carbon nanotubes is 1 to 4 mg / mL.

[0026] In some embodiments, the temperature of the microwave heat treatment is 150-210° C., and the time of the microwave heat treatment is 5-40 minutes.

[0027] In some embodiments, during the microwave heat treatment, the second mixed system is stirred at a rotation speed of 300 to 900 rpm.

[0028] In some embodiments, the calcination temperature is 160-240° C., and the calcination time is 1-3 hours.

[0029] In some embodiments, the calcination process is carried out in an atmosphere of protective gas.

[0030] In some embodiments, the solid is dried before the calcination, the drying temperature is 60 to 90° C., and the drying time is 5 to 10 hours.

[0031] A positive electrode sheet comprises the composite positive electrode material, or the composite positive electrode material prepared by the method for preparing the composite positive electrode material.

[0032] A battery comprises the positive electrode sheet.

[0033] An electrical device comprises the battery.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) The composite positive electrode material of the present invention has abundant vacancies and reaction sites in the amorphous manganese-based oxide structure, thereby providing more ion transport channels, shortening the ion diffusion distance, and effectively promoting the solid-state diffusion kinetics of zinc ions. The amorphous manganese-based oxide can effectively buffer the volume change caused by the ion insertion / extraction process, reduce the collapse of the electrode material structure, and improve the cycle performance of the battery; the amorphous manganese-based oxide is uniformly coated on the surface of the carbon nanotube to form a composite positive electrode material, and by introducing the conductive medium carbon nanotube, a "amorphous manganese-based oxide nanoparticle / conductive medium" conductive network is constructed. Since the carbon nanotube has super strong conductivity, it can improve the low conductivity of the manganese-based oxide. At the same time, the strong interface interaction between the manganese oxide nanoparticles and CNTs can fix the nanoparticles, prevent agglomeration, alleviate structural collapse, and improve the cycle life of the composite positive electrode material.

[0036] (2) The preparation method of the composite positive electrode material of the present invention is based on the combination of organic solvent and chelating agent to achieve confined growth effect. By introducing conductive medium carbon nanotubes and adopting microwave heat treatment, amorphous manganese-based oxide nanoparticles are induced to grow uniformly in the conductive network, thereby realizing the controllable synthesis of the composite positive electrode material. The method has a mild reaction, the reaction products are precisely controllable, the microwave synthesis method has a fast reaction rate and short time consumption, and has the potential for large-scale production. The reaction raw materials are safe, low-toxic and low-pollution.

[0037] (3) The battery of the present invention has excellent cycle performance, rate performance and safety performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 X-ray diffraction patterns (XRD) of the composite cathode material in Example 2 of the present invention and the composite cathode material in Comparative Example 1;

[0040] Figure 2 This is a transmission electron microscope image (TEM) of the composite cathode material in Example 2 of the present invention;

[0041] Figure 3 These are AC impedance spectra of the composite positive electrode material in Example 2 of the present invention and the composite positive electrode material in Comparative Example 1. DETAILED DESCRIPTION

[0042] The embodiments of the present invention will be described in detail below with reference to the examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention. Where specific conditions are not specified in the examples, the methods were performed according to conventional conditions or the conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments are not specified, they are all commercially available conventional products.

[0043] A composite cathode material comprising carbon nanotubes (CNTs) and amorphous manganese-based oxide nanoparticles located on the surface of the carbon nanotubes, wherein the amorphous manganese-based oxide nanoparticles have the general chemical formula (NiO) x (MnO) y , 0.25≤x≤0.75, 0.25≤y≤0.75, and x+y=1.

[0044] The composite cathode material of the present invention features abundant vacancies and reaction sites within its amorphous manganese-based oxide structure, providing more ion transport channels and shortening the ion diffusion distance, thereby effectively promoting the solid-state diffusion kinetics of zinc ions. More importantly, the amorphous manganese-based oxide effectively buffers volume changes caused by ion insertion / extraction, reducing the collapse of the electrode material structure and significantly improving the battery's cycle performance. The amorphous manganese-based oxide is uniformly coated on the surface of carbon nanotubes, and by introducing the conductive medium carbon nanotubes, a "amorphous manganese-based oxide nanoparticle / conductive medium" conductive network is constructed. Due to the exceptionally strong conductivity of CNTs, the low conductivity of the manganese-based oxide can be improved. Furthermore, the strong interfacial interaction between the manganese oxide nanoparticles and CNTs stabilizes the nanoparticles, preventing agglomeration and mitigating structural collapse, thereby increasing the cycle life of the composite cathode material.

[0045] In some embodiments, x is 0.25, 0.3, 0.4, 0.5, 0.6, 0.7 or 0.75, etc., and y is 0.25, 0.3, 0.4, 0.5, 0.6, 0.7 or 0.75, etc.

[0046] In some embodiments, the amorphous manganese-based oxide comprises (NiO) 0.5 (MnO) 0.5 、(NiO) 0.75 (MnO) 0.25 and (NiO) 0.25 (MnO) 0.75 At least one of .

[0047] In some embodiments, the average particle size of the amorphous manganese-based oxide is 6 to 12 nm, such as 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, or 12 nm. The amorphous manganese-based oxide of the present invention has a suitable average particle size and grows uniformly along the surface of CNTs.

[0048] In some embodiments, the mass content of the amorphous manganese-based oxide nanoparticles in the composite positive electrode material is 70% to 90%, for example, 70%, 75%, 80%, 85%, or 90%. A suitable proportion of the amorphous manganese-based oxide nanoparticles in the composite positive electrode material is more conducive to improving the electrochemical performance of the positive electrode material.

[0049] According to another aspect of the present invention, the present invention also relates to a method for preparing a composite positive electrode material, comprising the following steps:

[0050] A first mixed system of a manganese source, a nickel source, an organic solvent and a chelating agent is mixed with carbon nanotubes to obtain a second mixed system. The second mixed system is subjected to microwave heat treatment, solid-liquid separation is performed, and solids are collected and calcined.

[0051] The preparation method of the composite positive electrode material of the present invention is based on the combination of an organic solvent and a chelating agent to achieve confined growth. By introducing conductive medium carbon nanotubes and using microwave heat treatment, amorphous manganese-based oxide nanoparticles are induced to grow uniformly in the conductive network, thereby achieving controllable synthesis of the composite positive electrode material.

[0052] In some embodiments, the manganese source includes manganese acetate and / or manganese acetylacetonate.

[0053] In some embodiments, the nickel source includes nickel acetate and / or nickel acetylacetonate.

[0054] In some embodiments, the organic solvent comprises benzyl alcohol.

[0055] In some embodiments, the chelating agent comprises 1,3-propylene glycol.

[0056] In some embodiments, the manganese source and the nickel source of the present invention are used in an appropriate molar ratio, and the molar ratio of the manganese source to the nickel source is (0.5-2):1. For example, 0.5:1, 0.6:1, 0.8:1, 1:1, 1.2:1, 1.5:1, 1.8:1 or 2:1.

[0057] In some embodiments, in the first mixed system, the concentration of the manganese source is 50 to 150 mmol / L, for example, 50 mmol / L, 60 mmol / L, 80 mmol / L, 100 mmol / L, 120 mmol / L, 130 mmol / L, 150 mmol / L, etc. The concentration of the nickel source is 50 to 150 mmol / L, for example, 50 mmol / L, 60 mmol / L, 80 mmol / L, 100 mmol / L, 120 mmol / L, 130 mmol / L, 150 mmol / L, etc. The manganese source and nickel source have appropriate concentrations to ensure subsequent reactions and facilitate the formation of amorphous manganese-based oxide nanoparticles of appropriate size.

[0058] In some embodiments, the volume ratio of the organic solvent to the chelating agent is (4-19):1, for example, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 15:1, 17:1, or 19:1. In some embodiments, the organic solvent and the chelating agent are used in an appropriate volume ratio to ensure that the two cooperate in a confining effect, thereby obtaining amorphous manganese-based oxide nanoparticles of appropriate particle size.

[0059] In some embodiments, the method for preparing the first mixed system specifically includes: mixing and stirring the manganese source, the nickel source, the solvent, and the chelating agent for 10 to 20 minutes, for example, 10 minutes, 11 minutes, 12 minutes, 15 minutes, 16 minutes, 18 minutes, 20 minutes, etc. The present invention adopts an appropriate mixing and stirring time to ensure that the raw materials are fully mixed and dissolved.

[0060] In some embodiments, in the second mixed system, the concentration of carbon nanotubes is 1 to 4 mg / mL, for example, 1 mg / mL, 1.5 mg / mL, 2 mg / mL, 2.5 mg / mL, 3 mg / mL, 3.5 mg / mL, or 4 mg / mL. The carbon nanotubes in the second mixed system have an appropriate concentration, which is more conducive to the growth of amorphous manganese-based oxide nanoparticles on their surface, thereby improving the overall electrochemical performance of the composite positive electrode material. If the amount of carbon nanotubes added is too low, the conductivity of the composite material will not be significantly improved; if the amount of carbon nanotubes added is too high, the proportion of active material in the composite positive electrode material will be low, resulting in a decrease in the specific capacity of the material.

[0061] In some embodiments, the temperature of the microwave heat treatment is 150-210°C, for example, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, or any range therebetween. The duration of the microwave heat treatment is 5-40 min, for example, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, or 40 min. In some embodiments, the second mixed system is stirred during the microwave heat treatment at a speed of 300-900 rpm, for example, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, or the like. The microwave heat treatment uses a microwave reactor equipped with a magnetic stirring device. The purpose of the stirring includes: ensuring uniform heating of the reaction solution during the reaction. By combining the above-mentioned microwave heat treatment conditions, the present invention achieves mild reaction conditions, precisely controllable reaction products, and a fast reaction rate, allowing the materials to fully react and uniformly grow amorphous manganese-based oxide nanoparticles on the surface of the carbon nanotubes. If the microwave reaction temperature is too low or the reaction time is too short, the reaction will be incomplete, resulting in a decrease in product yield; if the microwave reaction temperature is too high or the reaction time is too long, the reaction will be excessive, resulting in crystallization of nanoparticles.

[0062] In some embodiments, the solid-liquid separation is performed by centrifugal solid-liquid separation, and the solids after the solid-liquid separation are washed, and the washing agent includes ether.

[0063] In some embodiments, the calcination temperature is 160-240°C, such as 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, etc., and the calcination time is 1-3h, such as 1h, 1.5h, 2h, 2.5h, 3h, etc. The calcination atmosphere is a protective gas, such as argon. The present invention adopts low-temperature calcination to remove organic groups in the product and enhance the conductivity of the material. The calcination temperature and time of the present invention are suitable, which is more conducive to ensuring that the composite positive electrode material has high capacity and excellent cyclability; if the calcination temperature is too low or the calcination time is too short, the organic groups will not be removed cleanly; if the calcination temperature is too high or the calcination time is too long, the amorphous nanoparticles will be recrystallized, destroying the amorphous structure.

[0064] In some embodiments, the solid is dried before calcination at a temperature of 60 to 90° C., such as 60° C., 70° C., 80° C., or 90° C. The drying time is 5 to 10 hours, such as 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours.

[0065] According to another aspect of the present invention, the present invention relates to a positive electrode sheet, comprising the composite positive electrode material, or the composite positive electrode material prepared by the method for preparing the composite positive electrode material.

[0066] The positive electrode sheet of the present invention comprises a positive electrode current collector and a positive electrode material layer arranged on at least one side surface of the positive electrode current collector. The positive electrode material layer contains the composite positive electrode material, a conductive agent and a binder.

[0067] According to another aspect of the present invention, the present invention relates to a battery comprising the above-mentioned positive electrode sheet.

[0068] The battery of the present invention has excellent cycle performance, rate performance and safety performance.

[0069] In some embodiments, the battery comprises a zinc ion battery, comprising a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte.

[0070] According to another aspect of the present invention, the present invention relates to an electric device comprising the above-mentioned battery, such as an electric vehicle.

[0071] The following is further explained with reference to specific embodiments and comparative examples.

[0072] Example 1

[0073] A method for preparing a composite positive electrode material comprises the following steps:

[0074] (1) Weigh 0.375 mmol of manganese acetate and 0.375 mmol of nickel acetate and transfer them to a 10 mL microwave reaction tube. Weigh 4.75 mL of anhydrous benzyl alcohol and 0.25 mL of 1,3-propylene glycol and transfer them to the microwave reaction tube. Stir for 15 min until the solid powder is completely dissolved in the mixture of benzyl alcohol and 1,3-propylene glycol to obtain a first mixed system.

[0075] (2) 14 mg of carbon nanotubes were added to the first mixed system and stirred to form a stable second mixed system.

[0076] (3) Insert the microwave reaction tube into the inner cavity of the microwave reactor, set the parameters of the microwave reactor as follows: maximum temperature of 160° C., heating time of 30 min, and rotation speed of 600 rpm, and perform microwave heat treatment on the second mixed system.

[0077] (4) The product after microwave heat treatment was centrifuged, the precipitate was taken, washed with ether three times, and dried in an oven at 80°C for 8 hours to obtain the primary product. The primary product was calcined in a tube furnace under argon atmosphere, heated to 200°C at a heating rate of 3°C / min and kept at this temperature for 2 hours, and then cooled naturally to obtain amorphous (NiO) 0.5 (MnO) 0.5 / CNTs composite positive electrode materials.

[0078] Example 2

[0079] A method for preparing a composite positive electrode material comprises the following steps:

[0080] (1) Weigh 0.375 mmol of manganese acetate and 0.375 mmol of nickel acetate and transfer them to a 10 mL microwave reaction tube. Weigh 4.5 mL of anhydrous benzyl alcohol and 0.5 mL of 1,3-propylene glycol and transfer them to the microwave reaction tube. Stir for 15 min until the solid powder is completely dissolved in the benzyl alcohol and 1,3-propylene glycol mixture to obtain a first mixed system.

[0081] (2) Add 14 mg of carbon nanotubes to the first mixed system and stir evenly to form a stable second mixed system.

[0082] (3) Insert the microwave reaction tube into the inner cavity of the microwave reactor, set the parameters of the microwave reactor as follows: maximum temperature of 160° C., heating time of 30 min, and rotation speed of 600 rpm, and perform microwave heat treatment on the second mixed system.

[0083] (4) The product after microwave heat treatment was centrifuged, the precipitate was taken, washed with ether three times, and finally dried in an oven at 80°C for 8 hours to obtain the primary product. The primary product was calcined in a tube furnace under argon atmosphere, heated to 200°C at a heating rate of 3°C / min and kept at this temperature for 2 hours, and then cooled naturally to obtain amorphous (NiO) 0.5 (MnO) 0.5 / CNTs composite positive electrode materials.

[0084] Example 3

[0085] A method for preparing a composite positive electrode material comprises the following steps:

[0086] (1) Weigh 0.375 mmol of manganese acetate and 0.375 mmol of nickel acetate and transfer them to a 10 mL microwave reaction tube. Weigh 4.25 mL of anhydrous benzyl alcohol and 0.75 mL of 1,3-propylene glycol and transfer them to the microwave reaction tube. Stir for 15 min until the solid powder is completely dissolved in the mixture of benzyl alcohol and 1,3-propylene glycol to obtain a first mixed system.

[0087] (2) Add 14 mg of carbon nanotubes to the first mixed system and stir evenly to form a stable second mixed system.

[0088] (3) Insert the microwave reaction tube into the inner cavity of the microwave reactor, set the parameters of the microwave reactor as follows: maximum temperature of 160° C., heating time of 30 min, and rotation speed of 600 rpm, and perform microwave heat treatment on the second mixed system.

[0089] (4) The product after microwave heat treatment was centrifuged to obtain a precipitate, washed with ether three times, and finally dried in an oven at 80°C for 8 hours to obtain a primary product. The primary product was calcined in a tube furnace under an argon atmosphere, heated to 200°C at a heating rate of 3°C / min and kept at this temperature for 2 hours, and then cooled naturally to obtain an amorphous NiO. 0.5 (MnO) 0.5 / CNTs composite positive electrode materials.

[0090] Example 4

[0091] A method for preparing a composite positive electrode material, which differs from Example 2 in that:

[0092] In step (2), 5 mg of carbon nanotubes were added to the first mixed system and stirred to form a stable second mixed system.

[0093] Example 5

[0094] A method for preparing a composite positive electrode material, which differs from Example 2 in that:

[0095] In step (2), 20 mg of carbon nanotubes were added to the first mixed system and stirred to form a stable second mixed system.

[0096] Example 6

[0097] A method for preparing a composite positive electrode material, which differs from Example 2 in that:

[0098] In step (3), the microwave reaction tube is inserted into the inner cavity of the microwave reactor, and the parameters of the microwave reactor are set as follows: the maximum temperature is 150° C., and the heating time is 5 minutes.

[0099] Example 7

[0100] A method for preparing a composite positive electrode material, which differs from Example 2 in that:

[0101] In step (3), the microwave reaction tube is inserted into the inner cavity of the microwave reactor, and the parameters of the microwave reactor are set as follows: the maximum temperature is 210° C., and the heating time is 40 min.

[0102] Example 8

[0103] A method for preparing a composite positive electrode material, which differs from Example 2 in that:

[0104] In step (4), the mixture was heated to 160°C at a heating rate of 3°C / min and kept at this temperature for 1 hour.

[0105] Example 9

[0106] A method for preparing a composite positive electrode material, which differs from Example 2 in that:

[0107] In step (4), the mixture is heated to 240°C at a heating rate of 3°C / min and kept at this temperature for 3 hours.

[0108] Comparative Example 1

[0109] A method for preparing a composite positive electrode material comprises the following steps:

[0110] (1) Weigh 0.375 mmol of manganese acetate and 0.375 mmol of nickel acetate and transfer them to a 10 mL microwave reaction tube. Measure 5 mL of anhydrous benzyl alcohol and transfer it to the microwave reaction tube. Stir for 15 min until the solid powder is completely dissolved in the benzyl alcohol.

[0111] (2) Add 14 mg of carbon nanotubes and stir evenly to form a stable dispersion.

[0112] (3) Insert the microwave reaction tube into the cavity of the microwave reactor and set the parameters of the microwave reactor as follows: maximum temperature 160°C, heating time 30min, and speed 600rpm. The product after the reaction was centrifuged to obtain the precipitate, washed with ether 3 times, and finally dried in an oven at 80°C for 8h to obtain the primary product. The primary product was calcined in a tube furnace under argon atmosphere, heated to 200°C at a heating rate of 3°C / min and kept at this temperature for 2h, and then cooled naturally to obtain crystalline (NiO) 0.5 (MnO) 0.5 / CNTs composite positive electrode materials.

[0113] Experimental example

[0114] 1. XRD and TEM images of composite cathode materials

[0115] The XRD patterns of the composite cathode material in Example 2 of the present invention and the composite cathode material in Comparative Example 1 are shown in FIG. Figure 1 As shown, it can be seen that the diffraction peaks at 36.5°, 42°, 61°, 73° and 77° in the XRD spectrum of the composite positive electrode material of Comparative Example 1 correspond to the metal oxide (NiO) 0.5 (MnO) 0.5 The diffraction peak indicated by the heart icon at 24° corresponds to carbon nanotubes. In contrast, the XRD pattern of Example 2 has no obvious diffraction peaks. This is because the introduction of the chelating agent 1,3-propylene glycol triggers the confinement effect, inhibiting the growth of metal oxide nanoparticles, resulting in the formation of amorphous (NiO) 0.5 (MnO) 0.5 / CNTs composite positive electrode materials.

[0116] The TEM image of the composite cathode material in Example 2 of the present invention is as follows: Figure 2As shown, it can be seen that the average particle size of the amorphous manganese-based oxide nanoparticles is 10 nm, and the nanoparticles grow uniformly along the surface of CNTs.

[0117] 2. Battery electrochemical performance test

[0118] The composite positive electrode materials of each embodiment and comparative example are respectively prepared to obtain zinc ion batteries, comprising the following steps:

[0119] (1) Preparation of positive electrode sheet: Disperse polyvinylidene fluoride, conductive carbon black, and composite positive electrode material in an appropriate amount of N-methylpyrrolidone at a mass ratio of 7:2:1, stir evenly to form a slurry of appropriate consistency, apply it on a 10μm commercial titanium foil, and vacuum dry to obtain a positive electrode sheet. The positive electrode sheet is punched into a circular sheet with a diameter of 12mm and directly used as the positive electrode of zinc ion batteries. The active material loading is about 1mg / cm 2 .

[0120] (2) Preparation of negative electrode sheet: After wiping clean the 80 μm commercial zinc foil with anhydrous ethanol, it was punched into a circular sheet with a diameter of 16 mm and directly used as the negative electrode of the zinc ion battery.

[0121] (3) Preparation of electrolyte: Use zinc sulfate heptahydrate as solute and deionized water as solvent to prepare a 2 mol / L zinc sulfate solution, which is directly used as the electrolyte for zinc ion batteries.

[0122] (4) Assemble the zinc ion battery in the order of negative electrode shell-negative electrode sheet-diaphragm-electrolyte-positive electrode sheet-gasket-spring-positive electrode shell. The amount of electrolyte used is 150 mL, the battery shell model is CR2032, and the diaphragm model is glass fiber diaphragm (GF / D).

[0123] At current densities of 1 A / g and 2 A / g, the electrochemical performance of the batteries of each embodiment and comparative example was tested, and the test results are shown in Table 1. The AC impedance spectra of the composite positive electrode material in Example 2 and the composite positive electrode material in Comparative Example 1 are shown in Table 1. Figure 3 shown.

[0124] Table 1 Electrochemical performance test results of the battery

[0125]

[0126]

[0127] As shown in Table 1, the battery produced from the composite cathode material of the present invention exhibits excellent electrochemical performance, with a capacity retention rate of 72.7% after 500 cycles and 75.4% after 1000 cycles. In Comparative Example 1, where no 1,3-propylene glycol was added, the battery produced from the crystalline composite cathode material exhibited significantly lower capacity retention rates.

[0128] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite positive electrode material, characterized in that The present invention comprises carbon nanotubes and amorphous manganese-based oxide nanoparticles located on the surface of the carbon nanotubes, wherein the chemical formula of the amorphous manganese-based oxide nanoparticles is (NiO) x (MnO) y , 0.25≤x≤0.75, 0.25≤y≤0.75, and x+y=1.

2. The composite cathode material according to claim 1, wherein The amorphous manganese-based oxide nanoparticles include (NiO) 0.5 (MnO) 0.5 、(NiO) 0.75 (MnO) 0.25 and (NiO) 0.25 (MnO) 0.75 At least one of; and / or, the average particle size of the amorphous manganese-based oxide nanoparticles is 6 to 12 nm; And / or, the mass content of the amorphous manganese-based oxide nanoparticles in the composite positive electrode material is 70% to 90%.

3. The method for preparing a composite positive electrode material according to claim 1 or 2, wherein: The following steps are involved: mixing a first mixed system of a manganese source, a nickel source, an organic solvent, and a chelating agent with carbon nanotubes to obtain a second mixed system, subjecting the second mixed system to microwave heat treatment, performing solid-liquid separation, collecting a solid, and performing a calcination treatment; The temperature of the microwave heat treatment is 150-210° C., and the time of the microwave heat treatment is 5-40 minutes; The temperature of the calcination treatment is 160-240° C., and the time of the calcination treatment is 1-3 hours.

4. The method for preparing a composite positive electrode material according to claim 3, wherein: Contains at least one of the following features (1) to (8): (1) The manganese source includes manganese acetate and / or manganese acetylacetonate; (2) The nickel source includes nickel acetate and / or nickel acetylacetonate; (3) The organic solvent includes benzyl alcohol; (4) The chelating agent includes 1,3-propylene glycol; (5) The molar ratio of the manganese source to the nickel source is (0.5-2):1; (6) In the first mixed system, the concentration of the manganese source is 50-150 mmol / L, and the concentration of the nickel source is 50-150 mmol / L; (7) The volume ratio of the organic solvent to the chelating agent is (4-19):1; (8) The preparation method of the first mixed system specifically comprises: mixing a manganese source, a nickel source, an organic solvent and a chelating agent and stirring for 10 to 20 minutes.

5. The method for preparing a composite positive electrode material according to claim 3, wherein: In the second mixed system, the concentration of the carbon nanotubes is 1-4 mg / mL.

6. The method for preparing a composite cathode material according to claim 3, wherein: During the microwave heat treatment, the second mixed system is stirred at a rotation speed of 300-900 rpm.

7. The method for preparing a composite cathode material according to claim 3, wherein: Contains at least one of the following features (1) to (2): (1) The atmosphere of the calcination treatment is a protective gas; (2) Before the roasting process, the solid matter is dried at a temperature of 60 to 90° C. for 5 to 10 hours.

8. A positive electrode sheet, characterized in that: The invention relates to a composite positive electrode material comprising the composite positive electrode material according to claim 1 or 2, or a composite positive electrode material prepared by the method for preparing the composite positive electrode material according to claims 3 to 7.

9. A battery, characterized in that: Contains the positive electrode sheet according to claim 8.

10. An electrical device, characterized in that: A battery comprising the battery according to claim 9.

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