Battery positive electrode material as well as preparation method and application thereof

Abstract

The invention discloses a battery positive electrode material and a preparation method and application thereof, the battery positive electrode material is oxyhydroxide of aluminum, cobalt and nickel three metals, in the oxyhydroxide, the molar ratio of aluminum element to cobalt element to nickel element is x: y: z, the sum of x, y and z is 1, x is more than or equal to 0.05 and less than or equal to 0.15, and y is more than or equal to 0.25 and less than or equal to 0.35. The preparation method comprises the following steps: dissolving an aluminum salt, a cobalt salt and a nickel salt in deionized water to prepare a metal salt solution, then adding an alkali solution, reacting to generate a precipitate, and washing and drying the obtained precipitate to obtain precursor powder; preparing the precursor powder into slurry, coating a substrate with the slurry, and drying to obtain a precursor pole piece; and oxidizing the precursor pole piece in a three-electrode system through cyclic voltammetry to obtain the battery positive electrode material. The battery positive electrode material has relatively high energy density as the water-based magnesium ion battery positive electrode, and the current situation that the energy density of the current water-based magnesium ion battery positive electrode is relatively low is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and in particular relates to a positive electrode material for a battery, a preparation method thereof, and an application thereof. Background Art

[0002] The rapid development of society has led to a growing demand for energy, which has also promoted the development of efficient energy storage technology. In recent years, aqueous magnesium-ion batteries have received widespread attention due to their own advantages. Magnesium is cheap and has abundant reserves on the earth, which can effectively reduce costs. In addition, compared with traditional organic electrolytes, aqueous electrolytes have the advantages of being non-flammable, safe and non-toxic, and having higher ionic conductivity, avoiding the safety problems that may be caused by organic electrolytes. For this reason, aqueous magnesium-ion batteries are a promising aqueous energy storage system.

[0003] However, the further development and application of aqueous magnesium-ion batteries are limited by the bottleneck of positive electrode materials. First, most magnesium-ion battery positive electrodes are matched with organic electrolytes, and there are very few types of positive electrode materials that match aqueous electrolytes. Currently, they are mainly manganese-based oxides, vanadium-based oxides and Prussian blue analogs. Secondly, the discharge capacity and operating voltage of the current aqueous magnesium-ion battery positive electrode are at a low level, which greatly limits the energy density of aqueous magnesium-ion batteries.

[0004] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0005] The object of the present invention is to provide a battery positive electrode material, a preparation method thereof and an application thereof, wherein the battery positive electrode material has a high energy density and a capacity retention rate, and can solve the problem of low energy density of the positive electrode of the current aqueous magnesium ion battery.

[0006] In order to achieve the above object, a technical solution provided by a specific embodiment of the present invention is as follows:

[0007] A battery positive electrode material is a trimetallic oxyhydroxide of aluminum, cobalt and nickel. In the oxyhydroxide, the molar ratio of aluminum, cobalt and nickel in terms of atomic number is x:y:z, wherein the sum of x, y and z is 1, 0.05≤x≤0.15, and 0.25≤y≤0.35.

[0008] Another specific embodiment of the present invention provides a technical solution as follows:

[0009] A method for preparing the battery positive electrode material according to claim 1, comprising:

[0010] S1. Dissolve aluminum salt, cobalt salt and nickel salt in deionized water to prepare a metal salt solution, then add an alkali solution to react to generate a precipitate, wash and dry the obtained precipitate to obtain a precursor powder;

[0011] S2, preparing the precursor powder into slurry, coating the slurry on the substrate, and drying to obtain the precursor electrode;

[0012] S3. Oxidizing the precursor electrode by cyclic voltammetry in a three-electrode system to obtain a positive electrode material for a battery.

[0013] In one or more embodiments of the present invention, in step S1, the total concentration of aluminum ions, cobalt ions and nickel ions in the metal salt solution is 0.2-0.5 mol / L.

[0014] In one or more embodiments of the present invention, in step S1, the molar ratio of the alkali to the sum of the metal ions in the metal salt solution is (2-2.5):1.

[0015] In one or more embodiments of the present invention, in step S2, the precursor powder, the conductive agent, and the binder are dispersed in a solvent in a mass ratio of (7-8): (1-2): 1 to prepare a slurry.

[0016] In one or more embodiments of the present invention, in step S3, the oxidation operation is: at a voltage of -0.15 to 0.55 V, and at a scan rate of 15 to 25 mV / s, cycle 8 to 12 times.

[0017] In one or more embodiments of the present invention, the aluminum salt is at least one of aluminum nitrate and aluminum sulfate.

[0018] In one or more embodiments of the present invention, the cobalt salt is at least one of cobalt nitrate and cobalt sulfate.

[0019] In one or more embodiments of the present invention, the nickel salt is at least one of nickel nitrate and nickel sulfate.

[0020] Another specific embodiment of the present invention provides a technical solution as follows:

[0021] Application of the above battery positive electrode material or the battery positive electrode material prepared by the above battery positive electrode material preparation method in aqueous magnesium ion batteries.

[0022] Compared with the prior art, the battery positive electrode material in the present invention uses a high proportion of nickel as the main active element in the charging and discharging process, and introduces an appropriate amount of cobalt to improve the capacity retention rate of the positive electrode material, and introduces an appropriate amount of aluminum to improve the energy density of the positive electrode material. The prepared battery positive electrode material can be used as an electrode of an aqueous magnesium ion battery and has a high energy density, which effectively solves the current low energy density of the positive electrode of an aqueous magnesium ion battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 Comparison of the charge and discharge curves of the aluminum-cobalt-nickel trimetallic oxyhydroxide in Example 1 of the present invention and the nickel oxyhydroxide in Comparative Example 1 as the positive electrode of an aqueous magnesium ion battery in a three-electrode system;

[0025] Figure 2 Comparison of the cycle capacity retention rates of the aluminum-cobalt-nickel trimetallic oxyhydroxide in Example 1 of the present invention and the nickel oxyhydroxide in Comparative Example 1 as the positive electrode of an aqueous magnesium ion battery in a three-electrode system;

[0026] Figure 3 The charge and discharge curve of the aluminum-cobalt-nickel trimetallic oxyhydroxide as the positive electrode of an aqueous magnesium ion battery in a three-electrode system in Example 2 of the present invention;

[0027] Figure 4 The charge and discharge curve of the aluminum-cobalt-nickel trimetallic oxyhydroxide as the positive electrode of an aqueous magnesium ion battery in a three-electrode system in Example 3 of the present invention;

[0028] Figure 5 The charge and discharge curve of the aluminum-cobalt-nickel trimetallic oxyhydroxide as the positive electrode of an aqueous magnesium ion battery in a three-electrode system in Example 4 of the present invention;

[0029] Figure 6 The charge-discharge curve of the aluminum-cobalt-nickel trimetallic oxyhydroxide used as the positive electrode of an aqueous magnesium ion battery in a three-electrode system in Comparative Example 2 of the present invention;

[0030] Figure 7 This is the charge and discharge curve of the aluminum-cobalt-nickel trimetallic hydroxide used as the positive electrode of an aqueous magnesium ion battery in a three-electrode system in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0032] A specific embodiment of the present invention provides a battery positive electrode material, which is a hydroxide oxide of aluminum, cobalt and nickel. In the hydroxide oxide, the molar ratio of aluminum, cobalt and nickel in terms of atomic number is x:y:z, wherein the sum of x, y and z is 1, 0.05≤x≤0.15, and 0.25≤y≤0.35.

[0033] Specifically, nickel is the main active element in the charging and discharging process, and as a core element among the three metal elements, a high proportion needs to be maintained to ensure the positive electrode discharge specific capacity. The introduction of cobalt can significantly improve the capacity retention rate of the positive electrode material, and a certain proportion needs to be reached to have a more obvious effect of improving the capacity retention rate, but too high a proportion of nickel will reduce the proportion of nickel, thereby reducing the positive electrode discharge specific capacity. Therefore, the cobalt element ratio in the present invention is controlled within an appropriate range, and the positive electrode discharge specific capacity and capacity retention rate can be guaranteed at the same time. The introduction of aluminum can increase the discharge voltage of the positive electrode material, and then the energy density of the positive electrode material can be increased. The proportion of aluminum in the present invention has reached the point where the charging voltage of the positive electrode material is increased to the edge of the voltage window of the electrolyte, so the aluminum element ratio defined in the present invention can give full play to the role of aluminum in the positive electrode material.

[0034] Furthermore, specific values ​​of x, y and z can be selected within the range defined in the present invention, such as the specific value of x can be 0.05, 0.07, 0.09, 0.10, 0.012, 0.13 or 0.15, and the specific value of y can be 0.25, 0.28, 0.30, 0.32, 0.34 or 0.35.

[0035] Another specific embodiment of the present invention provides a method for preparing a positive electrode material for a battery, comprising steps 1-3.

[0036] Step 1: dissolving aluminum salt, cobalt salt and nickel salt in deionized water to prepare a metal salt solution, then adding an alkali solution to react to generate a precipitate, and washing and drying the obtained precipitate to obtain a precursor powder.

[0037] Specifically, the aluminum salt is at least one of aluminum nitrate and aluminum sulfate, the cobalt salt is at least one of cobalt nitrate and cobalt sulfate, the nickel salt is at least one of nickel nitrate and nickel sulfate, the alkali is at least one of sodium hydroxide and potassium hydroxide, and the alkali solution is an aqueous solution of alkali with a molar concentration of 2.5 to 3.5M.

[0038] The amount of raw materials used satisfies the following conditions: in the metal salt solution, the total concentration of aluminum ions, cobalt ions and nickel ions is 0.2-0.5 mol / L, and the molar ratio of the alkali to the sum of the metal ions in the metal salt solution is (2-2.5): 1. By controlling the amount of raw materials used, it is helpful to generate precipitates of aluminum salt, cobalt salt and nickel salt by coprecipitation.

[0039] The precipitate is washed with deionized water and anhydrous ethanol in turn, and then dried in an oven at 50-80°C for 8-16 hours. The unreacted salt and alkali on the surface of the precipitate can be removed by washing to ensure the purity of the product.

[0040] Step 2, prepare the precursor powder into slurry, apply the slurry on the substrate, and dry it to obtain the precursor electrode.

[0041] Specifically, the slurry is prepared as follows: the precursor powder, the conductive agent, and the binder are dispersed in a solvent, the mass ratio of the precursor powder, the conductive agent, and the binder is (7-8): (1-2): 1, and the ratio of the binder to the solvent is 10-20 mg / ml, that is, 1 ml of solvent is used for every 10-20 mg of the binder. Among them, acetylene black is selected as the conductive agent, polyvinylidene fluoride is selected as the binder, and N-methylpyrrolidone is selected as the solvent. The substrate is carbon cloth, and the thickness of the slurry coated on the carbon cloth substrate is 100-200 μm. After coating, it is dried in an oven at 50-80°C for 8-16 hours.

[0042] Step 3: Oxidize the precursor electrode by cyclic voltammetry in a three-electrode system to obtain a positive electrode material for a battery.

[0043] Specifically, the precursor electrode is used as the working electrode, the carbon electrode is used as the counter electrode, the silver / silver chloride is used as the reference electrode, and the oxidizing solution is a 1M potassium hydroxide solution. Cyclic voltammetry is used at a voltage of -0.15 to 0.55 V and a scan rate of 15 to 25 mV / s for 8 to 12 cycles.

[0044] Another specific implementation of the present invention provides the use of the above-mentioned battery positive electrode material or the battery positive electrode material prepared by the above-mentioned method for preparing the battery positive electrode material in an aqueous magnesium ion battery.

[0045] Specifically, the battery positive electrode material of the present invention has a higher energy density when used as the positive electrode of an aqueous magnesium ion battery.

[0046] The present invention is further described in detail below in conjunction with specific embodiments.

[0047] Example 1

[0048] The battery positive electrode material is specifically prepared as follows:

[0049] (1) Preparation of precursor powder

[0050] 0.0015 mol aluminum nitrate, 0.0045 mol cobalt nitrate and 0.009 mol nickel nitrate were added to 40 mL deionized water, stirred and fully dissolved, and then 10 mL of 3M potassium hydroxide solution was added dropwise to generate a precipitate. The lower precipitate in the solution was taken, washed with deionized water and anhydrous ethanol, and then dried in an oven at 60°C for 12 hours to obtain a precursor powder.

[0051] (2) Preparation of precursor slurry

[0052] Precursor powder, acetylene black and polyvinylidene fluoride were dispersed in N-methylpyrrolidone at a mass ratio of 7:2:1, using 1 ml of N-methylpyrrolidone for every 10 mg of polyvinylidene fluoride, to prepare a precursor slurry.

[0053] (3) Preparation of precursor electrode sheets

[0054] The precursor slurry was evenly coated on the carbon cloth substrate with a coating thickness of 200 μm, and then dried in an oven at 60° C. to prepare a precursor electrode.

[0055] (4) Electrode Oxidation

[0056] The precursor electrode was oxidized in a three-electrode system, the oxidizing solution was a 1M potassium hydroxide solution, the precursor electrode was the working electrode, the carbon electrode was the counter electrode, and silver / silver chloride was the reference electrode. Cyclic voltammetry was used to cycle 10 times at a scan rate of 20mV / s in the voltage range of -0.15 to 0.55V to obtain aluminum-cobalt-nickel trimetallic hydroxide, i.e., the positive electrode material for the battery.

[0057] Example 2

[0058] The battery positive electrode material is specifically prepared as follows:

[0059] (1) Preparation of precursor powder

[0060] 0.0005 mol aluminum nitrate, 0.0035 mol cobalt nitrate and 0.006 mol nickel nitrate were added to 27 mL deionized water, stirred and fully dissolved, and then 7 mL of 3M potassium hydroxide solution was added dropwise to generate a precipitate. The lower precipitate in the solution was taken, washed with deionized water and anhydrous ethanol, and then dried in an oven at 60°C for 12 hours to obtain a precursor powder.

[0061] (2) Preparation of precursor slurry

[0062] Precursor powder, acetylene black and polyvinylidene fluoride were dispersed in N-methylpyrrolidone at a mass ratio of 7:2:1, using 1 ml of N-methylpyrrolidone for every 10 mg of polyvinylidene fluoride, to prepare a precursor slurry.

[0063] (3) Preparation of precursor electrode sheets

[0064] The precursor slurry was evenly coated on the carbon cloth substrate with a coating thickness of 200 μm, and then dried in an oven at 60° C. to prepare a precursor electrode.

[0065] (4) Electrode Oxidation

[0066] The precursor electrode was oxidized in a three-electrode system, the oxidizing solution was a 1M potassium hydroxide solution, the precursor electrode was the working electrode, the carbon electrode was the counter electrode, and silver / silver chloride was the reference electrode. Cyclic voltammetry was used to cycle 10 times at a scan rate of 20mV / s in the voltage range of -0.15 to 0.55V to obtain aluminum-cobalt-nickel trimetallic hydroxide, i.e., the positive electrode material for the battery.

[0067] Example 3

[0068] The battery positive electrode material is specifically prepared as follows:

[0069] (1) Preparation of precursor powder

[0070] 0.0015 mol aluminum nitrate, 0.0025 mol cobalt nitrate and 0.006 mol nickel nitrate were added to 27 mL deionized water, stirred and fully dissolved, and then 7 mL of 3M potassium hydroxide solution was added dropwise to generate a precipitate. The lower precipitate in the solution was taken, washed with deionized water and anhydrous ethanol, and then dried in an oven at 60°C for 12 hours to obtain a precursor powder.

[0071] (2) Preparation of precursor slurry

[0072] Precursor powder, acetylene black and polyvinylidene fluoride were dispersed in N-methylpyrrolidone at a mass ratio of 7:2:1, using 1 ml of N-methylpyrrolidone for every 10 mg of polyvinylidene fluoride, to prepare a precursor slurry.

[0073] (3) Preparation of precursor electrode sheets

[0074] The precursor slurry was evenly coated on the carbon cloth substrate with a coating thickness of 200 μm, and then dried in an oven at 60° C. to prepare a precursor electrode.

[0075] (4) Electrode Oxidation

[0076] The precursor electrode was oxidized in a three-electrode system, the oxidizing solution was a 1M potassium hydroxide solution, the precursor electrode was the working electrode, the carbon electrode was the counter electrode, and silver / silver chloride was the reference electrode. Cyclic voltammetry was used to cycle 10 times at a scan rate of 20mV / s in the voltage range of -0.15 to 0.55V to obtain aluminum-cobalt-nickel trimetallic hydroxide, i.e., the positive electrode material for the battery.

[0077] Example 4

[0078] The battery positive electrode material is specifically prepared as follows:

[0079] (1) Preparation of precursor powder

[0080] 0.0015 mol aluminum nitrate, 0.0035 mol cobalt nitrate and 0.005 mol nickel nitrate were added to 27 mL deionized water, stirred and fully dissolved, and then 7 mL of 3M potassium hydroxide solution was added dropwise to generate a precipitate. The lower precipitate in the solution was taken, washed with deionized water and anhydrous ethanol, and then dried in an oven at 60°C for 12 hours to obtain a precursor powder.

[0081] (2) Preparation of precursor slurry

[0082] Precursor powder, acetylene black and polyvinylidene fluoride were dispersed in N-methylpyrrolidone at a mass ratio of 7:2:1, using 1 ml of N-methylpyrrolidone for every 10 mg of polyvinylidene fluoride, to prepare a precursor slurry.

[0083] (3) Preparation of precursor electrode sheets

[0084] The precursor slurry was evenly coated on the carbon cloth substrate with a coating thickness of 200 μm, and then dried in an oven at 60° C. to prepare a precursor electrode.

[0085] (4) Electrode Oxidation

[0086] The precursor electrode was oxidized in a three-electrode system, the oxidizing solution was a 1M potassium hydroxide solution, the precursor electrode was the working electrode, the carbon electrode was the counter electrode, and silver / silver chloride was the reference electrode. Cyclic voltammetry was used to cycle 10 times at a scan rate of 20mV / s in the voltage range of -0.15 to 0.55V to obtain aluminum-cobalt-nickel trimetallic hydroxide, i.e., the positive electrode material for the battery.

[0087] Comparative Example 1

[0088] The battery positive electrode material is specifically prepared as follows:

[0089] (1) Preparation of precursor powder

[0090] 0.015 mol of nickel nitrate was added to 40 mL of deionized water, and after stirring to fully dissolve, 10 mL of 3 M potassium hydroxide solution was added dropwise to generate a precipitate. The lower precipitate in the solution was taken, and the precipitate was washed with deionized water and anhydrous ethanol, and then dried in an oven at 60 ° C for 12 hours to obtain a precursor powder.

[0091] (2) Preparation of precursor slurry

[0092] Precursor powder, acetylene black and polyvinylidene fluoride were dispersed in N-methylpyrrolidone at a mass ratio of 7:2:1, using 1 ml of N-methylpyrrolidone for every 10 mg of polyvinylidene fluoride, to prepare a precursor slurry.

[0093] (3) Preparation of precursor electrode sheets

[0094] The precursor slurry was evenly coated on the carbon cloth substrate with a coating thickness of 200 μm, and then dried in an oven at 60° C. to prepare a precursor electrode.

[0095] (4) Electrode Oxidation

[0096] The precursor electrode was oxidized in a three-electrode system, the oxidizing solution was a 1M potassium hydroxide solution, the precursor electrode was the working electrode, the carbon electrode was the counter electrode, and silver / silver chloride was the reference electrode. Cyclic voltammetry was used to cycle 10 times at a scan rate of 20mV / s in the voltage range of -0.15 to 0.55V to obtain nickel oxyhydroxide, i.e., the positive electrode material of the battery.

[0097] Comparative Example 2

[0098] The battery positive electrode material is specifically prepared as follows:

[0099] (1) Preparation of precursor powder

[0100] 0.0015 mol aluminum nitrate, 0.0075 mol cobalt nitrate and 0.006 mol nickel nitrate were added to 40 mL deionized water, stirred and fully dissolved, and then 10 mL of 3M potassium hydroxide solution was added dropwise to generate a precipitate. The lower precipitate in the solution was taken, washed with deionized water and anhydrous ethanol, and then dried in an oven at 60°C for 12 hours to obtain a precursor powder.

[0101] (2) Preparation of precursor slurry

[0102] Precursor powder, acetylene black and polyvinylidene fluoride were dispersed in N-methylpyrrolidone at a mass ratio of 7:2:1, using 1 ml of N-methylpyrrolidone for every 10 mg of polyvinylidene fluoride, to prepare a precursor slurry.

[0103] (3) Preparation of precursor electrode sheets

[0104] The precursor slurry was evenly coated on the carbon cloth substrate with a coating thickness of 200 μm, and then dried in an oven at 60° C. to prepare a precursor electrode.

[0105] (4) Electrode Oxidation

[0106] The precursor electrode was oxidized in a three-electrode system, the oxidizing solution was a 1M potassium hydroxide solution, the precursor electrode was the working electrode, the carbon electrode was the counter electrode, and silver / silver chloride was the reference electrode. Cyclic voltammetry was used to cycle 10 times at a scan rate of 20mV / s in the voltage range of -0.15 to 0.55V to obtain aluminum-cobalt-nickel trimetallic hydroxide, i.e., the positive electrode material for the battery.

[0107] Comparative Example 3

[0108] The battery positive electrode material is specifically prepared as follows:

[0109] (1) Preparation of precursor powder

[0110] 0.0045 mol aluminum nitrate, 0.0045 mol cobalt nitrate and 0.006 mol nickel nitrate were added to 40 mL deionized water, stirred and fully dissolved, and then 10 mL of 3M potassium hydroxide solution was added dropwise to generate a precipitate. The lower precipitate in the solution was taken, washed with deionized water and anhydrous ethanol, and then dried in an oven at 60°C for 12 hours to obtain a precursor powder.

[0111] (2) Preparation of precursor slurry

[0112] Precursor powder, acetylene black and polyvinylidene fluoride were dispersed in N-methylpyrrolidone at a mass ratio of 7:2:1, using 1 ml of N-methylpyrrolidone for every 10 mg of polyvinylidene fluoride, to prepare a precursor slurry.

[0113] (3) Preparation of precursor electrode sheets

[0114] The precursor slurry was evenly coated on the carbon cloth substrate with a coating thickness of 200 μm, and then dried in an oven at 60° C. to prepare a precursor electrode.

[0115] (4) Electrode Oxidation

[0116] The precursor electrode was oxidized in a three-electrode system, the oxidizing solution was a 1M potassium hydroxide solution, the precursor electrode was the working electrode, the carbon electrode was the counter electrode, and silver / silver chloride was the reference electrode. Cyclic voltammetry was used to cycle 10 times at a scan rate of 20mV / s in the voltage range of -0.15 to 0.55V to obtain aluminum-cobalt-nickel trimetallic hydroxide, i.e., the positive electrode material for the battery.

[0117] The positive electrode material of the battery in the embodiment and the comparative example is used as the working electrode, the carbon electrode is used as the counter electrode, the silver / silver chloride electrode is used as the reference electrode, and the electrolyte solution is a magnesium salt aqueous solution, with a concentration of 1 mol / L in terms of magnesium ions, wherein the magnesium salt is at least one of magnesium sulfate and magnesium chloride, and the present invention uses a magnesium chloride aqueous solution. The positive electrode material of the battery is tested under the test condition of a current density of 500 mA / g, and the results are as follows Figure 1-7 shown.

[0118] Reference Figure 1-2 Compared with the nickel oxyhydroxide in Comparative Example 1, the aluminum-cobalt-nickel trimetallic oxyhydroxide in Example 1, when used as a positive electrode material for a battery, exhibits a higher discharge voltage and discharge specific capacity, and an energy density higher than that of Comparative Example 1. During the cycle, the capacity of the aluminum-cobalt-nickel trimetallic oxyhydroxide decays less and has better performance. Figure 3-5The aluminum-cobalt-nickel trimetallic oxyhydroxides in Examples 2-4 also exhibited higher discharge voltages and discharge specific capacities, indicating that the aluminum-cobalt-nickel trimetallic oxyhydroxides in the present invention have higher energy density.

[0119] The amount of cobalt in the aluminum-cobalt-nickel trimetallic oxyhydroxide in Comparative Example 2 exceeds the range specified in the present invention, and the amount of nickel in the aluminum-cobalt-nickel trimetallic oxyhydroxide in Comparative Example 3 exceeds the range specified in the present invention. Figure 6-7 It can be seen that when excessive cobalt or nickel is used, the nickel content will be reduced, the discharge capacity of the positive electrode material will be reduced, and thus the energy density will be reduced. This also verifies that the preparation of aluminum-cobalt-nickel trimetallic hydroxide according to the ratio disclosed in the present invention can ensure its better performance.

[0120] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0121] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A battery positive electrode material, characterized in that: It is a trimetallic oxyhydroxide of aluminum, cobalt and nickel. In the oxyhydroxide, the molar ratio of aluminum, cobalt and nickel in terms of atomic number is x:y:z, wherein the sum of x, y and z is 1, 0.05≤x≤0.15, and 0.25≤y≤0.

35.

2. A method for preparing a positive electrode material for a battery according to claim 1, characterized in that: include: S1. Dissolve aluminum salt, cobalt salt and nickel salt in deionized water to prepare a metal salt solution, then add an alkali solution to react to generate a precipitate, wash and dry the obtained precipitate to obtain a precursor powder; S2, preparing the precursor powder into slurry, coating the slurry on the substrate, and drying to obtain the precursor electrode; S3. Oxidizing the precursor electrode in a three-electrode system by cyclic voltammetry to obtain a positive electrode material for a battery.

3. The method for preparing a positive electrode material for a battery according to claim 2, characterized in that: In step S1, the total concentration of aluminum ions, cobalt ions and nickel ions in the metal salt solution is 0.2-0.5 mol / L.

4. The method for preparing a positive electrode material for a battery according to claim 2, characterized in that: In step S1, the molar ratio of the alkali to the sum of the metal ions in the metal salt solution is (2-2.5):

1.

5. The method for preparing a positive electrode material for a battery according to claim 2, characterized in that: In step S2, the precursor powder, the conductive agent, and the binder are dispersed in a solvent in a mass ratio of (7-8): (1-2): 1 to prepare a slurry.

6. The method for preparing a positive electrode material for a battery according to claim 2, characterized in that: In step S3, the oxidation operation is: at a voltage of -0.15 to 0.55 V, and at a scan rate of 15 to 25 mV / s, cycle 8 to 12 times.

7. The method for preparing a positive electrode material for a battery according to claim 2, characterized in that: The aluminum salt is at least one of aluminum nitrate and aluminum sulfate.

8. The method for preparing a positive electrode material for a battery according to claim 2, characterized in that: The cobalt salt is at least one of cobalt nitrate and cobalt sulfate.

9. The method for preparing a positive electrode material for a battery according to claim 2, characterized in that: The nickel salt is at least one of nickel nitrate and nickel sulfate.

10. Use of the battery positive electrode material according to claim 1 or the battery positive electrode material prepared by the preparation method of the battery positive electrode material according to any one of claims 2 to 9 in an aqueous magnesium ion battery.

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