P2 type nickel-manganese binary sodium battery positive electrode material, and preparation method and use therefor

Abstract

A P2 type nickel-manganese binary sodium battery positive electrode material and a preparation method and use therefor. The P2-type nickel-manganese binary sodium battery positive electrode material is doped and modified by an M element, and the chemical formula is: Na 0.67M xNi y(1-x)Mn (1-y)(1-x)O 2; wherein 0＜x≤0.01, 0.2≤y≤0.4, and the M element comprises any one or a combination of at least two of Zn, Mg, Cr, Ti or Al. The provided P2 type nickel-manganese binary sodium battery positive electrode material, by means of doping and modification of specific metal elements, can reduce the capacity degradation rate in the battery cycling process, and prolong the service life of the battery. In addition, the preparation process is simplified, the raw material cost is reduced, the economic benefit is improved, and commercial application is facilitated.

Description

A P2 type nickel-manganese binary sodium cathode material and its preparation method and application Technical Field

[0001] The present application belongs to the field of battery manufacturing technology and relates to a sodium positive electrode material, and in particular to a P2-type nickel-manganese binary sodium positive electrode material and its preparation method and application. Background Art

[0002] With the continuous development of emerging applications such as electric vehicles and smart grids, humans have placed higher demands on energy storage and conversion devices, and various secondary battery systems with high specific energy and low cost characteristics have been more widely studied. As the most successful and advanced rechargeable battery, lithium-ion batteries are widely used in portable electronic products and electric vehicles due to their advantages such as long cycle life and high volume energy density. However, due to the uneven distribution of lithium resources and price considerations, it is difficult to meet the growing market demand. In contrast, sodium resources are relatively abundant, inexpensive, and have similar physical and chemical properties to lithium. Therefore, sodium-ion batteries are considered to be a new type of energy storage device that is very likely to replace lithium-ion batteries in certain applications.

[0003] The performance of cathode materials has a crucial impact on the electrochemical performance of batteries. P2-type layered nickel-manganese oxides, with their high discharge voltage and capacity, are considered promising cathode materials. Furthermore, their precursors are essentially identical to those used for lithium-ion battery cathodes, facilitating rapid scale-up of production. However, the primary challenge with this type of material is its rapid capacity decay during cycling, limiting its commercial application in sodium-ion batteries.

[0004] It can be seen that how to provide a P2-type nickel-manganese binary sodium cathode material and its preparation method to slow down the capacity decay rate during battery cycling, extend the battery life, and at the same time simplify the preparation process, reduce raw material costs, improve economic benefits, and realize commercial applications has become an urgent problem that technical personnel in this field need to solve.

[0005] Summary of the Invention

[0006] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0007] In response to the shortcomings of the existing technology, the purpose of this application is to provide a P2-type nickel-manganese binary sodium cathode material and its preparation method and application. By doping and modifying the P2-type nickel-manganese binary sodium cathode material with specific metal elements, the capacity decay rate during the battery cycle is slowed down, the battery service life is extended, and at the same time, the preparation process is simplified, the raw material cost is reduced, the economic benefits are improved, and it is conducive to commercial application.

[0008] To achieve this goal, this application adopts the following technical solutions:

[0009] In the first aspect, the present application provides a P2 type nickel-manganese binary sodium cathode material, wherein the P2 type nickel-manganese binary sodium cathode material is modified by doping with an M element, and the chemical formula is: Na 0.67 M x Ni y(1-x) Mn(1-y)(1-x)O2.

[0010] Among them, 0<x≤0.01, 0.2≤y≤0.4, for example, x=0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009 or 0.01; y=0.2, 0.22, 0.24, 0.26, 0.28, 0.3, 0.32, 0.34, 0.36, 0.38 or 0.4, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0011] The M element includes any one or a combination of at least two of Zn, Mg, Cr, Ti or Al. Typical but non-limiting combinations include a combination of Zn and Mg, a combination of Mg and Cr, a combination of Cr and Ti, a combination of Ti and Al, a combination of Zn, Mg and Cr, a combination of Mg, Cr and Ti, a combination of Cr, Ti and Al, a combination of Zn, Mg, Cr and Ti, or a combination of Mg, Cr, Ti and Al.

[0012] The P2-type nickel-manganese binary sodium cathode material provided in this application is modified by doping with specific metal elements, which enhances the cycle stability of the cathode material, thereby slowing down the capacity decay rate during the battery cycle, extending the battery life, and facilitating commercial application.

[0013] In one embodiment, the particle size distribution of the P2-type nickel-manganese binary sodium cathode material is: 2.0 μm ≤ D50 ≤ 12.0 μm, for example, D50 = 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm, 5.0 μm, 5.5 μm, 6.0 μm, 6.5 μm, 7.0 μm, 7.5 μm, 8.0 μm, 8.5 μm, 9.0 μm, 9.5 μm, 10.0 μm, 10.5 μm, 11.0 μm, 11.5 μm or 12.0 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0014] In a second aspect, the present application provides a method for preparing the P2-type nickel-manganese binary sodium cathode material as described in the first aspect, the preparation method comprising the following steps:

[0015] (1) mixing nickel salt, manganese salt and deionized water to prepare a binary metal salt solution;

[0016] (2) adding a binary metal salt solution, a doping metal salt solution, a precipitant solution, a complexing agent solution, and a sodium percarbonate solution to a bottom liquid in parallel to perform a co-precipitation reaction, and obtaining a sodium electrode precursor after solid-liquid separation; the metal element in the doping metal salt solution comprises any one of Zn, Mg, Cr, Ti, or Al, or a combination of at least two thereof;

[0017] (3) Mixing the sodium battery precursor and the sodium source and sintering them to obtain a P2 type nickel-manganese binary sodium battery positive electrode material.

[0018] The preparation method provided in this application promotes the uniform distribution of doped metal elements in the sodium electrode precursor by adopting a co-precipitation process. The preparation process is simple, the raw material cost is low, the economic benefits are improved, and it is conducive to large-scale promotion and application.

[0019] In one embodiment, the nickel salt and manganese salt in step (1) are independently any one of sulfate, nitrate, acetate or chloride salts of the corresponding metal ions, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of sulfate and nitrate, a combination of nitrate and acetate, a combination of acetate and chloride, a combination of sulfate, nitrate and acetate, or a combination of nitrate, acetate and chloride.

[0020] In one embodiment, the total concentration of metal ions in the binary metal salt solution in step (1) is 2-4 mol / L, for example, 2 mol / L, 2.2 mol / L, 2.4 mol / L, 2.6 mol / L, 2.8 mol / L, 3 mol / L, 3.2 mol / L, 3.4 mol / L, 3.6 mol / L, 3.8 mol / L or 4 mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0021] In one embodiment, the precipitant in the precipitant solution in step (2) comprises any one or a combination of at least two of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate or ammonium bicarbonate. Typical but non-limiting combinations include a combination of sodium hydroxide and potassium hydroxide, a combination of potassium hydroxide and sodium carbonate, a combination of sodium carbonate and sodium bicarbonate, a combination of sodium bicarbonate and ammonium bicarbonate, a combination of sodium hydroxide, potassium hydroxide and sodium carbonate, a combination of potassium hydroxide, sodium carbonate and sodium bicarbonate, or a combination of sodium carbonate, sodium bicarbonate and ammonium bicarbonate. Sodium hydroxide may further be selected.

[0022] In one embodiment, the complexing agent in the complexing agent solution of step (2) includes any one of ammonia water, oxalic acid, sodium oxalate, citric acid, lactic acid, tartaric acid or EDTA, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of ammonia water and oxalic acid, a combination of oxalic acid and sodium oxalate, a combination of sodium oxalate and citric acid, a combination of citric acid and lactic acid, a combination of lactic acid and tartaric acid, a combination of tartaric acid and EDTA, a combination of ammonia water, oxalic acid and sodium oxalate, a combination of oxalic acid, sodium oxalate and citric acid, a combination of sodium oxalate, citric acid and lactic acid, a combination of citric acid, lactic acid and tartaric acid, or a combination of lactic acid, tartaric acid and EDTA.

[0023] In one embodiment, the base liquid in step (2) is a mixed solution of a precipitant, a complexing agent and deionized water.

[0024] In one embodiment, the concentration of the precipitant in the base solution of step (2) is 1-3 mol / L, for example, it can be 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.4 mol / L, 2.6 mol / L, 2.8 mol / L or 3 mol / L, but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0025] In one embodiment, the concentration of the complexing agent in the base solution of step (2) is 0.01-0.3 mol / L, for example, it can be 0.01 mol / L, 0.02 mol / L, 0.04 mol / L, 0.06 mol / L, 0.08 mol / L, 0.1 mol / L, 0.12 mol / L, 0.14 mol / L, 0.16 mol / L, 0.18 mol / L, 0.2 mol / L, 0.22 mol / L, 0.24 mol / L, 0.26 mol / L, 0.28 mol / L or 0.3 mol / L, but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0026] In one embodiment, the pH value of the base solution in step (2) is 7.0-12.3, for example, it can be 7.0, 7.2, 7.4, 7.6, 7.8, 8, 8.2, 8.4, 8.6, 8.8, 9, 9.2, 9.4, 9.6, 9.8, 10, 10.2, 10.4, 10.6, 10.8, 11, 11.2, 11.4, 11.6, 11.8, 12, 12.2 or 12.3, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0027] In one embodiment, the coprecipitation reaction in step (2) is carried out in a protective atmosphere, and the protective atmosphere includes any one or a combination of at least two of nitrogen, helium or argon. Typical but non-limiting combinations include a combination of nitrogen and helium, a combination of helium and argon, a combination of nitrogen and argon, or a combination of nitrogen, helium and argon, and nitrogen can further be selected.

[0028] In one embodiment, the temperature of the coprecipitation reaction in step (2) is 30-80°C, for example, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0029] In one embodiment, the coprecipitation reaction time in step (2) is 40-80 hours, for example, it can be 40 hours, 45 hours, 50 hours, 55 hours, 60 hours, 65 hours, 70 hours, 75 hours or 80 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0030] In one embodiment, the pH value of the solution in the coprecipitation reaction in step (2) is 7.0-12.0, for example, it can be 7.0, 7.2, 7.4, 7.6, 7.8, 8, 8.2, 8.4, 8.6, 8.8, 9, 9.2, 9.4, 9.6, 9.8, 10, 10.2, 10.4, 10.6, 10.8, 11, 11.2, 11.4, 11.6, 11.8 or 12, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0031] In one embodiment, the coprecipitation reaction in step (2) is accompanied by stirring, and the stirring rate is 150-450 rpm, for example, it can be 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm or 450 rpm, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0032] In one embodiment, the solid-liquid separation in step (2) comprises filtration and / or centrifugation.

[0033] In one embodiment, after the solid-liquid separation in step (2), the sodium electrolyte precursor is washed, dried, screened and iron removed in sequence.

[0034] In one embodiment, the washing is performed until the sodium precursor is neutral.

[0035] In one embodiment, the drying temperature is 50-150°C, for example, it can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C or 150°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] In one embodiment, the sodium source in step (3) includes sodium carbonate and / or sodium bicarbonate, and can further be sodium carbonate.

[0037] In one embodiment, the sintering process in step (3) includes a two-stage heating process, namely a first heating process and a second heating process.

[0038] In one embodiment, the target temperature of the first heating is 400-600°C, for example, it can be 400°C, 420°C, 440°C, 460°C, 480°C, 500°C, 520°C, 540°C, 560°C, 580°C or 600°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] In one embodiment, the first heating holding time is 4-6 hours, for example, it can be 4 hours, 4.2 hours, 4.4 hours, 4.6 hours, 4.8 hours, 5 hours, 5.2 hours, 5.4 hours, 5.6 hours, 5.8 hours or 6 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] In one embodiment, the target temperature of the second heating is 900-1000°C, for example, it can be 900°C, 910°C, 920°C, 930°C, 940°C, 950°C, 960°C, 970°C, 980°C, 990°C or 1000°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] In one embodiment, the second heating holding time is 10-12 hours, for example, it can be 10 hours, 10.2 hours, 10.4 hours, 10.6 hours, 10.8 hours, 11 hours, 11.2 hours, 11.4 hours, 11.6 hours, 11.8 hours or 12 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0042] In one embodiment, after the sintering treatment in step (3), the sodium cathode material is ground and sieved in sequence.

[0043] As an optional technical solution of the second aspect of the present application, the preparation method comprises the following steps:

[0044] (1) mixing a nickel salt, a manganese salt, and deionized water to prepare a binary metal salt solution having a total metal ion concentration of 2-4 mol / L; the nickel salt and the manganese salt are independently any one of sulfate, nitrate, acetate, or chloride salts of the corresponding metal ions, or a combination of at least two thereof;

[0045] (2) adding a binary metal salt solution, a doping metal salt solution, a precipitant solution, a complexing agent solution and a sodium percarbonate solution to a bottom liquid in parallel, and carrying out a coprecipitation reaction at 30-80° C. for 40-80 hours in a nitrogen atmosphere, and controlling the pH value of the solution to 7.0-12.0, accompanied by stirring at a rate of 150-450 rpm, filtering and / or centrifuging, washing to neutrality, drying at 50-150° C., and then screening and removing iron in sequence to obtain a sodium electrode precursor; the metal elements in the doping metal salt solution include Zn, Any one or a combination of at least two of Mg, Cr, Ti or Al; the precipitant in the precipitant solution includes sodium hydroxide; the complexing agent in the complexing agent solution includes any one or a combination of at least two of ammonia water, oxalic acid, sodium oxalate, citric acid, lactic acid, tartaric acid or EDTA; the base liquid is a mixed solution of the precipitant, the complexing agent and deionized water, and the concentration of the precipitant in the base liquid is 1-3 mol / L, the concentration of the complexing agent is 0.01-0.3 mol / L, and the pH value is 7.0-12.3;

[0046] (3) Mixing the sodium electrode precursor and sodium carbonate for sintering treatment, first heating to 400-600°C, keeping warm for 4-6 hours, then heating to 900-1000°C, keeping warm for 10-12 hours; after natural cooling, grinding and sieving to obtain P2 type nickel-manganese binary sodium electrode positive electrode material.

[0047] In a third aspect, the present application provides a sodium ion battery, which comprises the P2-type nickel-manganese binary sodium cathode material as described in the first aspect.

[0048] The numerical range described in this application includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, this application no longer exhaustively lists the specific point values ​​included in the range.

[0049] Compared with the prior art, the present invention has the following advantages:

[0050] (1) The P2-type nickel-manganese binary sodium cathode material provided in this application is modified by doping with specific metal elements, which enhances the cycle stability of the cathode material, thereby slowing down the capacity decay rate during the battery cycle, extending the battery life, and facilitating commercial application;

[0051] (2) The preparation method provided in this application promotes the uniform distribution of doped metal elements in the sodium electrode precursor by adopting a co-precipitation process. The preparation process is simple, the raw material cost is low, the economic benefits are improved, and it is conducive to large-scale promotion and application. DETAILED DESCRIPTION

[0052] The technical solution of this application is further explained below through specific implementation methods.

[0053] Example 1

[0054] This embodiment provides a P2-type nickel-manganese binary sodium cathode material and a preparation method thereof, the preparation method comprising the following steps:

[0055] (1) mixing nickel sulfate, manganese sulfate, and deionized water to prepare a binary metal salt solution having a total metal ion concentration of 3 mol / L;

[0056] (2) adding a binary metal salt solution, a zinc sulfate solution, a sodium hydroxide solution, an ammonia solution and a sodium percarbonate solution to a base liquid in parallel, carrying out a coprecipitation reaction at 60° C. for 80 h in a nitrogen atmosphere, controlling the pH value of the solution to 10.0, and stirring at a rate of 200 rpm, washing to neutrality after centrifugation, drying at 100° C., and then screening and removing iron in sequence to obtain a sodium electric precursor; the base liquid is a mixed solution of sodium hydroxide, ammonia water and deionized water, and the concentration of sodium hydroxide in the base liquid is 2 mol / L, the concentration of ammonia water is 0.2 mol / L, and the pH value is 10.2;

[0057] (3) Mixing the sodium electrode precursor and sodium carbonate for sintering treatment, first heating to 500 ° C, keeping warm for 5 hours, then heating to 950 ° C, keeping warm for 11 hours; after natural cooling, grinding and sieving to obtain P2 type nickel-manganese binary sodium electrode positive electrode material.

[0058] The P2 type nickel-manganese binary sodium cathode material obtained in this embodiment is modified by doping with Zn element, and its chemical formula is: Na 0.67 Zn 0.001 Ni 0.33 Mn 0.669 O2, particle size distribution is D50=12.0μm.

[0059] Example 2

[0060] This embodiment provides a P2-type nickel-manganese binary sodium cathode material and a preparation method thereof, the preparation method comprising the following steps:

[0061] (1) mixing nickel nitrate, manganese nitrate, and deionized water to prepare a binary metal salt solution having a total metal ion concentration of 2 mol / L;

[0062] (2) adding a binary metal salt solution, a magnesium nitrate solution, a sodium hydroxide solution, an oxalic acid solution and a sodium percarbonate solution to a base liquid in parallel, carrying out a coprecipitation reaction at 80° C. for 60 h in a nitrogen atmosphere, and controlling the pH value of the solution to 7.0, while stirring at a rate of 300 rpm, filtering and washing to neutrality, drying at 150° C., and then screening and removing iron in sequence to obtain a sodium electric precursor; the base liquid is a mixed solution of sodium hydroxide, oxalic acid and deionized water, and the concentration of sodium hydroxide in the base liquid is 1 mol / L, the concentration of oxalic acid is 0.01 mol / L, and the pH value is 7.0;

[0063] (3) Mixing the sodium electrode precursor and sodium carbonate for sintering treatment, first heating to 400 ° C, keeping warm for 6 hours, then heating to 900 ° C, keeping warm for 12 hours; after natural cooling, grinding and sieving to obtain P2 type nickel-manganese binary sodium electrode positive electrode material.

[0064] The P2 type nickel-manganese binary sodium cathode material obtained in this embodiment is modified by doping with Mg element, and its chemical formula is: Na 0.67 Mg 0.005 Ni 0.378 Mn 0.617 O2, particle size distribution is D50=6.0μm.

[0065] Example 3

[0066] This embodiment provides a P2-type nickel-manganese binary sodium cathode material and a preparation method thereof, the preparation method comprising the following steps:

[0067] (1) mixing nickel chloride, manganese chloride, and deionized water to prepare a binary metal salt solution having a total metal ion concentration of 4 mol / L;

[0068] (2) adding a binary metal salt solution, an aluminum chloride solution, a sodium hydroxide solution, a citric acid solution, and a sodium percarbonate solution to a base liquid in parallel, and carrying out a coprecipitation reaction at 30° C. for 40 h in a nitrogen atmosphere, and controlling the pH value of the solution to 12.0, accompanied by stirring at a rate of 450 rpm, centrifuging and washing to neutrality, drying at 150° C., and then screening and removing iron in sequence to obtain a sodium electric precursor; the base liquid is a mixed solution of sodium hydroxide, citric acid, and deionized water, and the concentration of sodium hydroxide in the base liquid is 3 mol / L, the concentration of citric acid is 0.3 mol / L, and the pH value is 12.3;

[0069] (3) Mixing the sodium electrode precursor and sodium carbonate for sintering treatment, first heating to 600°C, keeping warm for 4 hours, then heating to 1000°C, keeping warm for 10 hours; after natural cooling, grinding and sieving to obtain P2 type nickel-manganese binary sodium electrode positive electrode material.

[0070] The P2 type nickel-manganese binary sodium cathode material obtained in this embodiment is modified by doping with Al element, and its chemical formula is: Na 0.67 Al 0.01 Ni 0.208 Mn 0.782 O2, particle size distribution is D50=2.5μm.

[0071] Example 4

[0072] This embodiment provides a P2-type nickel-manganese binary sodium cathode material and a preparation method thereof. Except that the doping metal salt solution in step (2) is replaced with a chromium sulfate solution, the remaining steps and conditions of the preparation method are the same as those in Example 2, and therefore are not described in detail here.

[0073] The P2 type nickel-manganese binary sodium cathode material obtained in this embodiment is modified by doping with Cr element, and its chemical formula is: Na 0.67 Cr 0.005 Ni 0.328 Mn 0.667 O2, particle size distribution is D50=6.0μm.

[0074] Example 5

[0075] This embodiment provides a P2-type nickel-manganese binary sodium cathode material and a preparation method thereof. The preparation method is the same as that of Example 3 except that the doping metal salt solution in step (2) is replaced by a titanium nitrate solution. Therefore, the remaining steps and conditions are the same as those of Example 3 and are not described in detail here.

[0076] The P2 type nickel-manganese binary sodium cathode material obtained in this embodiment is modified by doping with Ti element, and its chemical formula is: Na 0.67 Ti 0.005 Ni 0.328 Mn 0.667 O2, particle size distribution is D50 = 2.4 μm.

[0077] Comparative Example 1

[0078] This comparative example provides a P2-type nickel-manganese binary sodium cathode material and a preparation method thereof, the preparation method comprising the following steps:

[0079] (1) mixing nickel sulfate, manganese sulfate, and deionized water to prepare a binary metal salt solution having a total metal ion concentration of 3 mol / L;

[0080] (2) adding a binary metal salt solution, a sodium hydroxide solution, an ammonia solution and a sodium percarbonate solution to a base liquid in parallel, carrying out a coprecipitation reaction at 60° C. for 80 h in a nitrogen atmosphere, controlling the pH value of the solution to 10.0, and stirring at a rate of 200 rpm, washing to neutrality after centrifugation, drying at 100° C., and then screening and removing iron in sequence to obtain a sodium electric precursor; the base liquid is a mixed solution of sodium hydroxide, ammonia water and deionized water, and the concentration of sodium hydroxide in the base liquid is 2 mol / L, the concentration of ammonia water is 0.2 mol / L, and the pH value is 10.2;

[0081] (3) Mixing the sodium electrode precursor and sodium carbonate for sintering treatment, first heating to 500 ° C, keeping warm for 5 hours, then heating to 950 ° C, keeping warm for 11 hours; after natural cooling, grinding and sieving to obtain P2 type nickel-manganese binary sodium electrode positive electrode material.

[0082] The chemical formula of the P2 type nickel-manganese binary sodium positive electrode material obtained in this comparative example is: Na 0.67 Ni 0.33 Mn 0.67 O2, particle size distribution is D50=12.0μm.

[0083] Performance Testing

[0084] At 25°C, the sodium cathode materials obtained in Examples 1-5 and Comparative Example 1 were used as the main positive electrode materials, and the sodium metal sheet was used as the negative electrode to assemble into CR2032 button batteries. Then, the electrochemical performance was tested in the voltage range of 2.0-4.2V and the discharge current density was 1C. The test results of the capacity retention rate after 500 cycles are shown in Table 1 below.

[0085] Table 1

[0086] It can be seen from Table 1 that compared with Comparative Example 1, Examples 1-5 can significantly improve the cycle performance of sodium battery positive electrode materials through element doping.

[0087] It can be seen that the P2-type nickel-manganese binary sodium cathode material provided in this application is modified by doping with specific metal elements, which enhances the cycle stability of the cathode material, thereby slowing down the capacity decay rate during the battery cycle, extending the battery life, and facilitating commercial application.

[0088] In addition, the preparation method provided in this application promotes the uniform distribution of doped metal elements in the sodium electrode precursor by adopting a co-precipitation process. The preparation process is simple, the raw material cost is low, the economic benefits are improved, and it is conducive to large-scale promotion and application.

[0089] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of this application. It should be understood that the above is only a specific embodiment of this application and is not intended to limit this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application should be included in the scope of protection of this application.

Claims

1. A P2-type nickel-manganese binary sodium-based cathode material, which is doped and modified with element M, and has the chemical formula: Na 0.67 M x Ni y(1-x) Mn(1-y)(1-x)O2; Among them, 0 < x ≤ 0.01, 0.2 ≤ y ≤ 0.4, and the M element includes any one or a combination of at least two of Zn, Mg, Cr, Ti, or Al.

2. The P2-type nickel-manganese binary sodium cathode material according to claim 1, wherein The particle size distribution of the P2-type nickel-manganese binary sodium cathode material is: 2.0 μm ≤ D50 ≤ 12.0 μm.

3. A method for preparing the P2-type nickel-manganese binary sodium cathode material according to claim 1 or 2, comprising the following steps: (1) Mix a nickel salt, a manganese salt, and deionized water to obtain a binary metal salt solution; (2) Add the binary metal salt solution, the doped metal salt solution, the precipitant solution, the complexing agent solution, and the sodium percarbonate solution into the bottom liquid in parallel for coprecipitation reaction, and obtain a sodium battery precursor after solid-liquid separation; the metal elements in the doped metal salt solution include any one or a combination of at least two of Zn, Mg, Cr, Ti, or Al; (3) Mix the sodium battery precursor and a sodium source for sintering treatment to obtain the P2-type nickel-manganese binary sodium cathode material.

4. The preparation method according to claim 3, wherein The nickel salt and the manganese salt in step (1) are each independently any one or a combination of at least two of sulfates, nitrates, acetates, or chlorides of the corresponding metal ions; Optionally, the total concentration of metal ions in the binary metal salt solution in step (1) is 2 - 4 mol / L.

5. The preparation method according to claim 3 or 4, wherein The precipitant in the precipitant solution in step (2) includes any one or a combination of at least two of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, or ammonium bicarbonate, and further preferably sodium hydroxide; Optionally, the complexing agent in the complexing agent solution in step (2) includes any one or a combination of at least two of ammonia water, oxalic acid, sodium oxalate, citric acid, lactic acid, tartaric acid, or EDTA; Optionally, the bottom liquid in step (2) is a mixed solution of a precipitant, a complexing agent, and deionized water; Optionally, the concentration of the precipitant in the bottom liquid in step (2) is 1 - 3 mol / L; Optionally, the concentration of the complexing agent in the bottom liquid in step (2) is 0.01 - 0.3 mol / L; Optionally, the pH value of the bottom liquid in step (2) is 7.0 - 12.

3.

6. The preparation method according to any one of claims 3-5, wherein, The coprecipitation reaction in step (2) is carried out in a protective atmosphere, and the protective atmosphere includes any one or a combination of at least two of nitrogen, helium, or argon, and further preferably nitrogen; Optionally, the temperature of the coprecipitation reaction in step (2) is 30 - 80 °C; Optionally, the time of the coprecipitation reaction in step (2) is 40 - 80 h; Optionally, the pH value of the coprecipitation reaction solution in step (2) is 7.0 - 12.0; Optionally, the coprecipitation reaction in step (2) is accompanied by stirring, and the stirring rate is 150 - 450 rpm.

7. The preparation method according to any one of claims 3-6, wherein, The solid-liquid separation in step (2) includes filtration and / or centrifugation; Optionally, after the solid-liquid separation in step (2), the sodium battery precursor is successively washed, dried, sieved, and de-ironed; Optionally, the washing is carried out until the sodium battery precursor is neutral; Optionally, the drying temperature is 50 - 150 °C.

8. The preparation method according to any one of claims 3-7, wherein, The sodium source in step (3) includes sodium carbonate and / or sodium bicarbonate, and further preferably sodium carbonate; Optionally, the sintering treatment in step (3) includes a two-stage heating process, namely the first heating and the second heating; Optionally, the target temperature of the first heating is 400-600°C, and the heat preservation time is 4-6h; Optionally, the target temperature of the second heating is 900-1000°C, and the heat preservation time is 10-12h; Optionally, after the sintering treatment in step (3), the sodium-ion battery cathode material is successively ground and sieved.

9. The preparation method according to any one of claims 3-8, wherein, The preparation method includes the following steps: (1) Mix nickel salt, manganese salt and deionized water to prepare a binary metal salt solution with a total metal ion concentration of 2-4 mol / L; the nickel salt and manganese salt are each independently any one or a combination of at least two of sulfates, nitrates, acetates or chlorides of the corresponding metal ions; (2) Add the binary metal salt solution, the doped metal salt solution, the precipitant solution, the complexing agent solution and the sodium percarbonate solution into the bottom liquid in a co-current manner. Carry out a co-precipitation reaction at 30-80°C for 40-80h in a nitrogen atmosphere, control the solution pH value to be 7.0-12.0, and at the same time stir at a rate of 150-450 rpm. After filtration and / or centrifugation, wash until neutral, dry at 50-150°C, and then sieve and remove iron successively to obtain a sodium-ion battery precursor; the metal elements in the doped metal salt solution include any one or a combination of at least two of Zn, Mg, Cr, Ti or Al; the precipitant in the precipitant solution includes sodium hydroxide; the complexing agent in the complexing agent solution includes any one or a combination of at least two of ammonia water, oxalic acid, sodium oxalate, citric acid, lactic acid, tartaric acid or EDTA; the bottom liquid is a mixed solution of a precipitant, a complexing agent and deionized water, and the concentration of the precipitant in the bottom liquid is 1-3 mol / L, the concentration of the complexing agent is 0.01-0.3 mol / L, and the pH value is 7.0-12.3; (3) Mix the sodium-ion battery precursor and sodium carbonate for sintering treatment. First, heat up to 400-600°C, keep warm for 4-6h, then heat up to 900-1000°C, keep warm for 10-12h; after natural cooling, grind and sieve to obtain a P2-type nickel-manganese binary sodium-ion battery cathode material.

10. A sodium-ion battery comprising the P2-type nickel-manganese binary sodium-ion battery cathode material as described in claim 1 or 2.

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