An aluminum manganate cathode material, a preparation method thereof and an application thereof

Abstract

The present invention provides a manganese aluminate cathode material, a preparation method thereof, and an application thereof, belonging to the technical field of aluminum ion batteries. First, an aluminum source and a manganese source are dispersed in water according to a stoichiometric ratio to obtain a precursor mixture; then, the precursor mixture is sequentially subjected to spray drying and sintering to obtain a manganese aluminate cathode material with the chemical formula Al x MnO2, where 1 / 9 ≤ x ≤ 2 / 3, having a cubic ferrimagnetic structure and a space group of Ia-3. A water-based aluminum ion battery is prepared by using the manganese aluminate cathode material provided by the present invention. At a current density of 500 mA / g, the working voltage platforms of the battery are 1.75 V and 1.35 V, and the discharge capacity is 309 mAh / g, which is a promising energy storage device.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum ion batteries, and particularly to a lithium manganate cathode material, a preparation method thereof, and an application thereof. Background Art

[0002] The development and utilization of fossil fuels have provided convenience for our lives and promoted social development. However, the utilization of these energy resources has brought serious environmental problems. Due to the overexploitation and use of fossil fuels, fossil reserves are being depleted, triggering an energy crisis. To solve these two urgent problems, people are forced to develop and utilize clean energies such as solar energy, tides, wind energy, and geothermal energy. These clean energies have the advantages of being rich, environmentally friendly, and renewable. However, these clean energies have strong spatio-temporal dependence and are unstable and intermittent. The most effective way to solve the energy crisis is to convert and store these renewable energies and release them in a stable manner. This urgent need has promoted the rapid development of high-efficiency energy storage products. Among the devices for storing clean energy, lithium ion batteries, which have the advantages of high voltage, repeated cycle stability, high energy density, etc., are widely used. However, the low reserves and uneven distribution of raw materials for lithium ion batteries, as well as the battery safety, etc., limit the application of lithium ion batteries in the field of large-scale stationary energy storage. Currently, there is an urgent need to develop an electrochemical energy storage system with the advantages of low cost, high energy density, cycle stability, and high safety.

[0003] Aluminum has a higher standard reduction potential and a very high specific capacity. At the same time, the storage mechanism of three-electron transfer induces a higher energy density for aluminum ion batteries. In addition, in terms of sustainable development, aluminum not only has the lowest cost compared with other metals (the price is only 1 / 150 of the price of metallic lithium), but also is the third most abundant element in the earth's crust. The cation radius of aluminum ions is small, and it has good transport kinetics. And aluminum has a higher electronegativity, and aluminum has reactivity and higher safety in air and moisture. Therefore, aluminum ion batteries are considered to be a promising multivalent ion battery.

[0004] Currently, the research on the cathode materials of aluminum ion batteries mainly focuses on transition metal oxides, Prussian blue analogs, organic compounds, and graphite materials. These materials have disadvantages such as low capacity, poor cycle stability, and poor rate performance, and there is still a large room for improvement before commercialization. Therefore, to achieve the secondary commercialization of aluminum ion batteries, the cathode materials still need to be further studied and explored. Finding a cathode material with a long cycle life, high capacity, low production cost, and simple preparation process has become a research hotspot and key issue for aluminum ion batteries. Summary of the Invention

[0005] The object of the present invention is to provide a manganese aluminate cathode material, a preparation method and an application thereof, so as to solve the technical problems of low capacity, poor cycle stability and poor rate performance of the cathode material of aluminum ion batteries in the prior art.

[0006] In order to achieve the above object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a manganese aluminate cathode material, and the chemical formula of the manganese aluminate cathode material is Al x MnO2, where 1 / 9 ≤ x ≤ 2 / 3; the structure of the manganese aluminate cathode material is a cubic ferromanganite structure, and the space group is Ia-3.

[0008] Preferably, the particles of the manganese aluminate cathode material are spherical or quasi-spherical, and D50 ≤ 25 μm.

[0009] The present invention provides a preparation method of a manganese aluminate cathode material, comprising the following steps:

[0010] (1) Dispersing an aluminum source and a manganese source in water according to a stoichiometric ratio to obtain a precursor mixture;

[0011] (2) Spray-drying and sintering the precursor mixture in sequence to obtain the manganese aluminate cathode material.

[0012] Preferably, in the step (1), the aluminum source includes one or more of aluminum nitrate, aluminum chloride, aluminum sulfate, aluminum trifluoromethanesulfonate, aluminum acetate, aluminum ethoxide, aluminum hydroxyoxalate, aluminum oxide and aluminum hydroxide; the manganese source includes one or more of manganese acetate, manganese sulfate, manganese nitrate, manganese chloride, manganese oxalate, manganese carbonate, manganese monoxide, manganese dioxide, manganese sesquioxide and manganese tetroxide; the precursor mixture is a precursor solution or a precursor slurry, wherein the molar concentration of metal ions in the precursor solution is 0.1 - 10.5 mol / L, and the solid content of the precursor slurry is 10 - 60 wt%.

[0013] Preferably, in the step (2), the spray-drying is pneumatic atomization drying or centrifugal atomization drying; pneumatic atomization drying is used when the precursor mixture is a precursor solution, wherein the inlet air temperature of the pneumatic atomization drying is 140 - 350 °C, the outlet air temperature is 60 - 150 °C, the flow rate is 1 - 50 mL / min, and the air pressure is 0.1 - 1 Mpa; centrifugal atomization drying is used when the precursor mixture is a precursor slurry, wherein the inlet air temperature during centrifugal atomization drying is 140 - 350 °C, the outlet air temperature is 60 - 150 °C, the pumping rate of the precursor slurry is 10 - 750 mL / min, and the rotation speed is 15000 - 30000 r / min.

[0014] Preferably, in the step (2), the sintering includes high-temperature sintering, microwave sintering or spark plasma sintering.

[0015] Preferably, the heating rate of the high-temperature sintering is 2-10 °C / min, the temperature is 600-1400 °C, and the heat preservation time is 5-72 h.

[0016] Preferably, the heating rate of the microwave sintering is 10-50 °C / min, the temperature is 600-1400 °C, and the heat preservation time is 0.5-8 h.

[0017] Preferably, the heating rate of the spark plasma sintering is 50-200 °C / min, the temperature is 700-1300 °C, the heat preservation time is 5-30 min, and the pressure is 2-10 kN.

[0018] The present invention provides an application of an aluminum manganate cathode material in an aluminum-ion battery. The aluminum-ion battery is composed of a negative electrode sheet, a positive electrode sheet, a separator, an electrolyte, and an aluminum-plastic film shell. The positive electrode sheet is made of a current collector and a positive electrode material slurry. The mass ratio of the aluminum manganate cathode material, a conductive agent, a binder, and a solvent in the positive electrode material slurry is 70-96:2-10:2-20:100-300.

[0019] Advantages of the present invention:

[0020] (1) The present invention provides an aluminum manganate cathode material with a stable structure and excellent performance, having the characteristics of high specific capacity, excellent cycling performance and rate performance. The aluminum-ion battery made of the aluminum manganate cathode material prepared by the present invention has a working voltage platform of 1.75 V and 1.35 V and a discharge capacity of 309 mAh / g at a current density of 500 mA / g, and is a promising energy storage device.

[0021] (2) The aluminum manganate cathode material of the present invention is prepared by a preparation method including preparation of a precursor solution or slurry, spray drying and sintering. The preparation method has the advantages of simple process, low cost and environmental friendliness, and is suitable for large-scale industrial production. Description of the drawings

[0022] Figure 1 Cycling performance graph of the Al 1 / 6 MnO2 cathode material prepared in Example 2;

[0023] Figure 2 Cycling performance graph of the Al 1 / 4 MnO2 cathode material prepared in Example 4;

[0024] Figure 3 XRD pattern of the Al 1 / 2 MnO2 cathode material prepared in Example 7;

[0025] Figure 4 Al prepared in Example 7 1 / 2 Cycling performance graph of the Al

[0026] Figure 5 Al prepared in Example 9 2 / 3 Scanning electron microscope image of the Al

[0027] Figure 6 Al prepared in Example 9 2 / 3 Cycling performance graph of the Al

[0028] Figure 7 Discharge curve graph of the aluminum ion battery prepared in Example 10 Detailed implementation manners

[0029] The present invention provides a manganese aluminate cathode material, and the chemical formula of the manganese aluminate cathode material is Al x MnO2, where 1 / 9 ≤ x ≤ 2 / 3; the structure of the manganese aluminate cathode material is a cubic ferrite-manganese ore type structure, and the space group is Ia-3

[0030] In the present invention, the chemical formula of the manganese aluminate cathode material is Al x MnO2, where x is preferably 1 / 9, 1 / 6, 1 / 4, 5 / 12, 1 / 3, 1 / 2, 7 / 12, 2 / 3

[0031] In the present invention, the particles of the manganese aluminate cathode material are spherical or quasi-spherical, and D50 ≤ 25 μm

[0032] The present invention provides a preparation method of a manganese aluminate cathode material, comprising the following steps

[0033] (1) Disperse an aluminum source and a manganese source in water according to a stoichiometric ratio to obtain a precursor mixture

[0034] (2) Spray-dry and sinter the precursor mixture in sequence to obtain the manganese aluminate cathode material

[0035] In the present invention, in the step (1), the aluminum source includes one or more of aluminum nitrate, aluminum chloride, aluminum sulfate, aluminum trifluoromethanesulfonate, aluminum acetate, aluminum ethoxide, aluminum hydroxyoxalate, aluminum oxide, and aluminum hydroxide, preferably one or more of aluminum nitrate, aluminum chloride, aluminum sulfate, aluminum trifluoromethanesulfonate, aluminum oxide, and aluminum hydroxide, and more preferably one or more of aluminum nitrate, aluminum chloride, aluminum sulfate, and aluminum oxide; the manganese source includes one or more of manganese acetate, manganese sulfate, manganese nitrate, manganese chloride, manganese oxalate, manganese carbonate, manganese monoxide, manganese dioxide, manganese sesquioxide, and manganese tetroxide, preferably one or more of manganese acetate, manganese sulfate, manganese nitrate, manganese chloride, manganese carbonate, manganese sesquioxide, and manganese tetroxide, and more preferably one or more of manganese acetate, manganese sulfate, manganese nitrate, manganese chloride, and manganese carbonate.

[0036] In the present invention, the precursor mixture is a precursor solution or a precursor slurry. The molar concentration of metal ions in the precursor solution is 0.1 - 10.5 mol / L, preferably 1 - 9 mol / L, and more preferably 2 - 8 mol / L; the solid content of the precursor slurry is 10 - 60 wt%, preferably 20 - 50 wt%, and more preferably 30 - 40 wt%.

[0037] In the present invention, in the step (2), the spray drying is pneumatic atomization drying or centrifugal atomization drying; when the precursor mixture is a precursor solution, pneumatic atomization drying is used. For pneumatic atomization drying, the inlet air temperature is 140 - 350 °C, preferably 170 - 320 °C, and more preferably 200 - 300 °C; the outlet air temperature is 60 - 150 °C, preferably 80 - 120 °C, and more preferably 90 - 110 °C; the air pressure is 0.1 - 1 Mpa, preferably 0.2 - 0.9 Mpa, and more preferably 0.3 - 0.8 Mpa; the flow rate is 1 - 50 mL / min, preferably 5 - 45 mL / min, and more preferably 10 - 40 mL / min; when the precursor mixture is a precursor slurry, centrifugal atomization drying is used. For centrifugal atomization drying, the inlet air temperature is 140 - 350 °C, preferably 170 - 320 °C, and more preferably 200 - 300 °C; the outlet air temperature is 60 - 150 °C, preferably 80 - 120 °C, and more preferably 90 - 110 °C; the pumping rate of the precursor slurry is 10 - 750 mL / min, preferably 20 - 700 mL / min, and more preferably 30 - 600 mL / min, and the rotation speed is 15000 - 30000 r / min, preferably 18000 - 28000 r / min, and more preferably 20000 - 25000 r / min.

[0038] In the present invention, in the step (2), the sintering includes high-temperature sintering, microwave sintering or spark plasma sintering, preferably high-temperature sintering or microwave sintering, and further preferably high-temperature sintering.

[0039] In the present invention, for the high-temperature sintering, the heating rate is 2 - 10 °C / min, preferably 4 - 8 °C / min, and further preferably 5 °C / min; the temperature is 600 - 1400 °C, preferably 700 - 1300 °C, and further preferably 800 - 1200 °C; the holding time is 5 - 72 h, preferably 10 - 60 h, and further preferably 15 - 55 h.

[0040] In the present invention, for the microwave sintering, the heating rate is 10 - 50 °C / min, preferably 15 - 45 °C / min, and further preferably 20 - 40 °C / min; the temperature is 600 - 1400 °C, preferably 700 - 1300 °C, and further preferably 800 - 1200 °C; the holding time is 0.5 - 8 h, preferably 1 - 7 h, and further preferably 2 - 6 h.

[0041] In the present invention, for the spark plasma sintering, the heating rate is 50 - 200 °C / min, preferably 70 - 180 °C / min, and further preferably 100 - 150 °C / min; the temperature is 700 - 1300 °C, preferably 800 - 1200 °C, and further preferably 900 - 1100 °C; the holding time is 5 - 30 min, preferably 8 - 25 min, and further preferably 10 - 20 min; the pressure is 2 - 10 kN, preferably 4 - 8 kN, and further preferably 5 - 7 kN.

[0042] The present invention provides an application of an aluminum manganate cathode material in an aluminum-ion battery. The aluminum-ion battery is composed of a negative electrode sheet, a positive electrode sheet, a separator, an electrolyte, and an aluminum-plastic film casing. The positive electrode sheet is made of a current collector and a positive electrode material slurry. The mass ratio of the aluminum manganate cathode material, a conductive agent, a binder, and a solvent in the positive electrode material slurry is 70 - 96:2 - 10:2 - 20:100 - 300.

[0043] In the present invention, the mass ratio of the aluminum manganate cathode material, a conductive agent, a binder, and a solvent in the positive electrode material slurry is 70 - 96:2 - 10:2 - 20:100 - 300, preferably 80 - 94:3 - 10:3 - 10:120 - 250, and further preferably 85 - 92:4 - 7:5 - 8:150 - 200.

[0044] In the present invention, the conductive agent is carbon black and / or acetylene black, the binder is polyvinylidene fluoride and / or polytetrafluoroethylene, and the solvent is N-methylpyrrolidone and / or water.

[0045] In the present invention, the coating density of the positive electrode sheet is 4 to 20 mg / cm 2 , preferably 5 to 18 mg / cm 2 , more preferably 7 to 15 mg / cm 2 .

[0046] The aluminum-ion battery prepared by the present invention can be applied to energy storage power stations, starting power supplies, mobile power supplies, electric two-wheel vehicles, electric boats, electric vehicles, and hybrid electric vehicles.

[0047] The technical solutions provided by the present invention will be described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0048] Example 1

[0049] (1) Aluminum nitrate and manganese acetate with a molar ratio of 1 / 9:1 were dispersed in deionized water and mechanically stirred to obtain a uniform precursor solution with a metal ion concentration of 1 mol / L;

[0050] (2) The precursor solution was spray-dried using a pneumatic atomization dryer. The inlet air temperature of the spray dryer was 140 °C, the outlet air temperature was 80 °C, the air pressure was 0.2 Mpa, and the peristaltic pump flow rate was 25 mL / min to obtain precursor powder. Then, the precursor powder was mechanically ground evenly and placed in a high-temperature sintering furnace. It was heated to 600 °C at a heating rate of 2 °C / min, held for 72 hours, cooled, crushed for 5 minutes, sieved through a 300-mesh sieve, and demagnetized using a demagnetizer to obtain cubic iron manganese oxide type Al 1 / 9MnO2 positive electrode material.

[0051] Example 2

[0052] (1) Aluminum nitrate and manganese acetate with a molar ratio of 1 / 6:1 were dispersed in deionized water and mechanically stirred to obtain a uniform precursor solution with a metal ion concentration of 3 mol / L;

[0053] (2) The precursor solution was spray-dried using a pneumatic atomization dryer. The inlet air temperature of the spray dryer was 350 °C, the outlet air temperature was 140 °C, the air pressure was 0.1 Mpa, and the peristaltic pump flow rate was 10 mL / min to obtain precursor powder. Then, the precursor powder was mechanically ground evenly and placed in a high-temperature sintering furnace. It was heated to 800 °C at a heating rate of 5 °C / min, held for 8 hours, cooled, crushed for 8 minutes, sieved through a 320-mesh sieve, and demagnetized using a demagnetizer to obtain cubic iron manganese oxide type Al 1 / 6MnO2 positive electrode material.

[0054] For Al 1 / 6The MnO2 cathode material, super carbon black, polyvinylidene fluoride (PVDF), and N-methylpyrrolidone (NMP) are mixed uniformly in a mass ratio of 80:10:10:200 to form a slurry, which is uniformly coated on a titanium foil and dried in vacuum at 120 °C for 12 hours to obtain a cathode sheet with a coating areal density of 4 mg / cm 2 。An electrochemical performance test is carried out using a three-electrode simulated battery. A platinum electrode is selected as the counter electrode, a silver / silver chloride electrode is selected as the reference electrode, and an aqueous aluminum chloride solution is used as the electrolyte.

[0055] Charge-discharge tests are carried out at a current density of 500 mA / g at room temperature, and the test voltage range is 0 to 1.2 V. Al 1 / The cycle performance test results of the Al Figure 1 6MnO2 cathode material are shown in

[0056] Example 3

[0057] (1) Aluminum chloride and manganese nitrate with a molar ratio of 1 / 6:1 are dispersed in deionized water and mechanically stirred to obtain a uniform precursor solution with a metal ion concentration of 2 mol / L;

[0058] (2) The precursor solution is spray-dried using a pneumatic atomization dryer. The inlet air temperature of the spray dryer is 220 °C, the outlet air temperature is 90 °C, the air pressure is 0.6 Mpa, and the peristaltic pump flow rate is 15 mL / min to obtain precursor powder; then the precursor powder is mechanically ground evenly and placed in a high-temperature sintering furnace, heated to 1200 °C at a heating rate of 10 °C / min, held for 5 hours, cooled and crushed for 8 minutes, sieved through a 320-mesh sieve, and demagnetized using a demagnetizer to obtain cubic iron manganese oxide type Al 1 / 6 MnO2 cathode material.

[0059] Example 4

[0060] (1) Aluminum oxide and manganese carbonate with a molar ratio of 1 / 8:1 are dispersed in deionized water and mechanically stirred to obtain a precursor slurry with a solid content of 20 wt%;

[0061] (2) The precursor slurry is spray-dried using a centrifugal atomization dryer. The inlet air temperature of the spray dryer is 270 °C, the outlet air temperature is 110 °C, the rotation speed of the centrifugal atomization dryer is 15000 r / min, and the slurry pumping rate is 50 mL / min to obtain precursor powder; then the precursor powder is mechanically ground evenly and placed in a microwave sintering furnace, heated to 900 °C at a heating rate of 10 °C / min, held for 8 hours, cooled and crushed for 10 minutes, sieved through a 300-mesh sieve, and demagnetized using a demagnetizer to obtain cubic iron manganese oxide type Al 1 / 4MnO2 cathode material.

[0062] Mix Al 1 / 4 MnO2 cathode material, super carbon black, polyvinylidene fluoride (PVDF), and N-methylpyrrolidone (NMP) evenly according to a mass ratio of 90:4:6:150 to make a slurry. Coat the slurry evenly on a titanium mesh and dry it in a vacuum at 120 °C for 12 hours to obtain a positive electrode sheet. The coating surface density is 9 mg / cm 2 . Use a three-electrode simulated battery to conduct an electrochemical performance test. Select a platinum electrode as the counter electrode, a silver / silver chloride electrode as the reference electrode, and an aluminum chloride aqueous solution as the electrolyte.

[0063] Conduct charge and discharge tests at a current density of 1000 mA / g at room temperature. The test voltage range is 0 to 1.2 V. The test results are shown in Figure 2 , and the initial discharge capacity of this cathode material is 175 mAh / g. After 100 cycles, it decays to 170 mAh / g.

[0064] Example 5

[0065] (1) Disperse aluminum nitrate and manganese carbonate with a molar ratio of 5 / 12:1 into deionized water and obtain a precursor slurry with a solid content of 50 wt% through mechanical stirring.

[0066] (2) Spray-dry the precursor slurry using a centrifugal atomization dryer. The inlet air temperature of the spray dryer is 250 °C, the outlet air temperature is 110 °C, the rotation speed of the centrifugal atomization dryer is 30000 r / min, and the slurry pumping rate is 20 mL / min to obtain a precursor powder. Then, after mechanically grinding the precursor powder evenly, place it in a microwave sintering furnace and heat it to 800 °C at a heating rate of 15 °C / min, hold for 8 hours, cool for 5 minutes, sieve it through a 200-mesh sieve, and demagnetize it with a demagnetizer to obtain cubic spinel-type Al 5 / 12 MnO2 cathode material.

[0067] Example 6

[0068] (1) Disperse aluminum nitrate and manganese sulfate with a molar ratio of 1 / 3:1 into deionized water and obtain a uniform precursor solution with a metal ion concentration of 1 mol / L through mechanical stirring.

[0069] (2) The precursor solution was spray-dried using a pneumatic atomization dryer. The inlet air temperature of the spray dryer was 250 °C, the outlet air temperature was 120 °C, the air pressure was 0.4 Mpa, and the peristaltic pump flow rate was 30 mL / min to obtain the precursor powder. Then, the precursor powder was mechanically ground evenly, loaded into a graphite mold, placed in a spark plasma sintering furnace, heated to 1000 °C at a heating rate of 50 °C / min, held for 15 min, cooled, crushed for 10 minutes, sieved through a 320-mesh sieve, and demagnetized using a demagnetizer to obtain cubic iron manganese oxide type Al 1 / 3 MnO2 cathode material.

[0070] The Al 1 / 3 MnO2 cathode material, acetylene black, polytetrafluoroethylene (PTFE), and deionized water were mixed evenly according to a mass ratio of 92:3:5:100 to form a slurry, which was evenly coated on a titanium mesh and vacuum-dried at 100 °C for 8 hours to obtain a positive electrode sheet with a coating surface density of 10 mg / cm 2 . Electrochemical performance tests were carried out using a Solvionic simulated battery and a three-electrode simulated battery. The counter electrode of the Solvionic simulated battery was an aluminum sheet, and the electrolyte was 1-ethyl-3-methylimidazolium chloride ionic liquid containing aluminum chloride. The counter electrode of the three-electrode simulated battery was a platinum electrode, the reference electrode was a silver / silver chloride electrode, and the electrolyte was an aqueous solution of aluminum chloride.

[0071] Charge-discharge tests were carried out at a current density of 500 mA / g at room temperature, and the test voltage range was 0 to 1.2 V. The initial discharge capacity of this cathode material was 114 mAh / g, and the capacity was 115 mAh / g after 200 cycles.

[0072] Example 7

[0073] (1) Aluminum chloride and manganese acetate with a molar ratio of 1 / 2:1 were dispersed in deionized water and mechanically stirred to obtain a uniform precursor solution with a metal ion concentration of 2 mol / L;

[0074] (2) The precursor solution was spray-dried using a pneumatic atomization dryer. The inlet air temperature of the spray dryer was 250 °C, the outlet air temperature was 60 °C, the air pressure was 0.3 Mpa, and the peristaltic pump flow rate was 50 mL / min to obtain the precursor powder. Then, the precursor powder was mechanically ground evenly, placed in a high-temperature sintering furnace, heated to 900 °C at a heating rate of 5 °C / min, held for 36 h, cooled, crushed for 5 minutes, sieved through a 300-mesh sieve, and demagnetized using a demagnetizer to obtain cubic iron manganese oxide type Al 1 / 2MnO2 cathode material.

[0075] The crystal structure of the Al 1 / 2 MnO2 cathode material was analyzed using XRD technology, as shown in Figure 3As shown, the material has a cubic hausmannite structure with a space group of Ia-3.

[0076] Al 1 / 2 The AlMnO₂ cathode material, acetylene black, polytetrafluoroethylene (PTFE), and deionized water were mixed uniformly in a mass ratio of 90:5:5:250 to form a slurry, which was uniformly coated on a titanium mesh and vacuum dried at 100 °C for 8 hours to obtain a cathode sheet with a coating surface density of 14 mg / cm 2 . A three-electrode simulated battery was used for electrochemical performance testing. A platinum electrode was used as the counter electrode, a silver / silver chloride electrode was used as the reference electrode, and an aqueous solution mixture of aluminum chloride and manganese sulfate was used as the electrolyte.

[0077] Charge-discharge tests were carried out at a current density of 500 mA / g at room temperature, and the test voltage range was 0 - 1.2 V. The test results are shown in Figure 4 , and the initial discharge capacity of this cathode material was 189 mAh / g, which decayed to 188 mAh / g after 100 cycles.

[0078] Example 8

[0079] (1) Aluminum chloride and manganese chloride with a molar ratio of 7 / 12:1 were dispersed in deionized water and mechanically stirred to obtain a uniform precursor solution with a metal ion concentration of 1 mol / L;

[0080] (2) The precursor solution was spray-dried using a pneumatic atomization dryer. The inlet air temperature of the spray dryer was 250 °C, the outlet air temperature was 100 °C, the air pressure was 0.5 Mpa, and the peristaltic pump flow rate was 20 mL / min to obtain precursor powder; then the precursor powder was mechanically ground evenly and placed in a high-temperature sintering furnace, heated to 1400 °C at a heating rate of 5 °C / min, held for 6 h, cooled and crushed for 5 minutes, sieved through a 300-mesh sieve, and demagnetized using a demagnetizer to obtain cubic hausmannite-type Al 7 / 12 MnO₂ cathode material.

[0081] Example 9

[0082] (1) Aluminum sulfate and manganese acetate with a molar ratio of 1 / 3:1 were dispersed in deionized water and mechanically stirred to obtain a uniform precursor solution with a metal ion concentration of 2 mol / L;

[0083] (2) The precursor solution was spray-dried using a pneumatic atomization dryer, where the inlet air temperature of the spray dryer was 260 °C, the outlet air temperature was 110 °C, the air pressure was 0.8 Mpa, and the peristaltic pump flow rate was 15 mL / min to obtain precursor powder; then the precursor powder was mechanically ground evenly and placed in a high-temperature sintering furnace, heated to 1200 °C at a heating rate of 5 °C / min, held for 8 h, cooled and pulverized for 10 minutes, sieved through a 320-mesh sieve, and demagnetized using a demagnetizer to obtain cubic iron manganese oxide type Al 2 / 3MnO2 cathode material.

[0084] The morphology of the Al 2 / 3 MnO2 cathode material was characterized using a scanning electron microscope, as Figure 5 shown. The particles of the cubic iron manganese oxide type Al 2 / 3 MnO2 cathode material prepared by the method of the present invention are spherical or quasi-spherical.

[0085] The Al 2 / 3 MnO2 cathode material, super carbon black, polyvinylidene fluoride (PVDF), and N-methylpyrrolidone (NMP) were mixed evenly according to a mass ratio of 85:7:8:180 to form a slurry, which was evenly coated on a titanium foil and vacuum-dried at 120 °C for 10 hours to obtain an Al 2 / 3 MnO2 cathode sheet, with a coating surface density of 5 mg / cm 2 . An electrochemical performance test was carried out using a three-electrode simulated battery. The counter electrode was a platinum electrode, the reference electrode was a silver / silver chloride electrode, and the electrolyte was an aqueous mixed solution of aluminum chloride and manganese sulfate.

[0086] Charge-discharge tests were carried out at a current density of 500 mA / g at room temperature, and the test voltage range was 0 - 1.2 V. The test results are shown in Figure 6 . The initial discharge capacity of this cathode material was 261 mAh / g, and the capacity was 245 mAh / g after 100 cycles.

[0087] Example 10

[0088] Using the Al 2 / 3 MnO2 cathode sheet, metallic aluminum anode sheet, glass fiber separator, aqueous mixed electrolyte of aluminum chloride and manganese sulfate, and aluminum plastic film shell provided in Example 9, an aqueous aluminum-ion battery was fabricated.

[0089] Charge-discharge tests were carried out at a current density of 500 mA / g at room temperature, and the voltage range was 0 - 1.9 V. The test results are shown in Figure 7 . The discharge platforms of the battery were 1.75 V and 1.35 V, the initial discharge capacity was 309 mAh / g, and the discharge capacity was 210 mAh / g after 50 cycles.

[0090] As can be seen from the above embodiments, the present invention provides an aluminum manganate positive electrode material and a preparation method and application thereof. First, an aluminum source and a manganese source are dispersed in water according to a stoichiometric ratio to obtain a precursor mixture; then the precursor mixture is spray-dried and sintered in sequence to obtain a positive electrode material with a chemical formula of Al x MnO2 aluminum manganate cathode material, where 1 / 9≤x≤2 / 3, has a cubic iron manganese ore structure and a space group of Ia-3. Aqueous aluminum ion batteries were prepared using aluminum manganate cathode materials. At a current density of 500mA / g, the operating voltage platform of the battery was 1.75V and 1.35V, and the discharge capacity was 309mAh / g. It is a very promising energy storage device.

[0091] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An aluminum manganate cathode material, characterized in that, The chemical formula of the aluminum manganese oxide cathode material is Al x MnO2, where 1 / 9 ≤ x ≤ 2 / 3; the structure of the aluminum manganese oxide cathode material is a cubic ferromanganese ore type structure, and the space group is Ia-3.

2. The aluminum manganate cathode material according to claim 1, wherein The particles of the aluminum manganate cathode material are spherical or quasi-spherical, where D50 ≤ 25 μm.

3. The preparation method of the aluminum manganate cathode material according to claim 1 or 2, characterized in that, It includes the following steps: (1) Disperse the aluminum source and the manganese source in water according to the stoichiometric ratio to obtain a precursor mixture; (2) Spray-dry and sinter the precursor mixture in sequence to obtain the aluminum manganate cathode material.

4. The preparation method according to claim 3, wherein In the step (1), the aluminum source includes one or more of aluminum nitrate, aluminum chloride, aluminum sulfate, aluminum trifluoromethanesulfonate, aluminum acetate, aluminum ethoxide, aluminum hydroxyoxalate, aluminum oxide, and aluminum hydroxide; the manganese source includes one or more of manganese acetate, manganese sulfate, manganese nitrate, manganese chloride, manganese oxalate, manganese carbonate, manganese monoxide, manganese dioxide, manganese sesquioxide, and manganese tetroxide; the precursor mixture is a precursor solution or a precursor slurry, where the molar concentration of metal ions in the precursor solution is 0.1 - 10.5 mol / L, and the solid content of the precursor slurry is 10 - 60 wt%.

5. The preparation method according to claim 4, characterized in that, In the step (2), the spray drying is pneumatic atomization drying or centrifugal atomization drying; when the precursor mixture is a precursor solution, pneumatic atomization drying is used, where the inlet air temperature of the pneumatic atomization drying is 140 - 350 °C, the outlet air temperature is 60 - 150 °C, the flow rate is 1 - 50 mL / min, and the air pressure is 0.1 - 1 Mpa; when the precursor mixture is a precursor slurry, centrifugal atomization drying is used, where the inlet air temperature during centrifugal atomization drying is 140 - 350 °C, the outlet air temperature is 60 - 150 °C, the pumping rate of the precursor slurry is 10 - 750 mL / min, and the rotation speed is 15000 - 30000 r / min.

6. The preparation method according to any one of claims 3 to 5, characterized in that, In the step (2), the sintering includes high-temperature sintering, microwave sintering, or spark plasma sintering.

7. The preparation method according to claim 6, characterized in that, The heating rate of the high-temperature sintering is 2 - 10 °C / min, the temperature is 600 - 1400 °C, and the holding time is 5 - 72 h.

8. The preparation method according to claim 6, characterized in that, The heating rate of the microwave sintering is 10 - 50 °C / min, the temperature is 600 - 1400 °C, and the holding time is 0.5 - 8 h.

9. The preparation method according to claim 6, characterized in that, The heating rate of the spark plasma sintering is 50 - 200 °C / min, the temperature is 700 - 1300 °C, the holding time is 5 - 30 min, and the pressure is 2 - 10 kN.

10. Use of the aluminum manganate cathode material according to claim 1 or 2 in an aluminum ion battery, characterized in that, The aluminum ion battery is composed of a negative electrode sheet, a positive electrode sheet, a separator, an electrolyte, and an aluminum-plastic film shell, where the positive electrode sheet is made of a current collector and a positive electrode material slurry; the mass ratio of the aluminum manganate cathode material, the conductive agent, the binder, and the solvent in the positive electrode material slurry is 70 - 96:2 - 10:2 - 20:100 - 300.

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