Multi-component layered oxide sodium-ion battery positive electrode material, preparation method therefor and use thereof

Abstract

The present application provides a multi-component layered oxide sodium-ion battery positive electrode material, a preparation method therefor and a use thereof. The chemical formula of the sodium-ion battery positive electrode material is: NaNixZnyMzO2, wherein 0.1≤x≤0.3, 0<y≤0.2, 0.3≤z≤0.6, and the M element is selected from any one or a combination of at least two of Ti, V, Cr, Mn, Fe, Co or Cu. According to the sodium-ion battery positive electrode material provided in the present application, low-cost Zn is introduced to partially replace metal Ni, so that the raw material costs are reduced while the energy density and the cycle life of the battery are improved, and the adverse effect of the battery material on the environment is mitigated, facilitating large-scale popularization and application.

Description

A multi-element layered sodium oxide 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 multi-layered oxide sodium positive electrode material and its preparation method and application. Background Art

[0002] Lithium-ion batteries have the characteristics of high energy density and long cycle life, and are expected to be widely used in energy storage systems to promote the transformation of human energy structure. However, due to the scarcity, uneven distribution and high price of lithium resources, their large-scale application is limited. As a suitable alternative, sodium-ion batteries have become an important development direction in the field of energy storage due to their abundant resource reserves and energy storage mechanisms similar to those of lithium-ion batteries. Like lithium-ion batteries, the energy storage effect of sodium-ion batteries is also mainly affected by the positive electrode material. Therefore, those skilled in the art are in urgent need of finding a positive electrode material with high energy density, low cost and long cycle time.

[0003] Currently, sodium-ion battery cathode materials primarily include layered oxides, polyanionic compounds, and Prussian blue compounds. Layered oxides, among others, are widely researched and applied due to their low cost and high capacity. Among the many active metal elements in layered oxides, nickel possesses a high capacity, and currently developed layered oxide sodium cathode materials with excellent electrochemical performance mostly contain around 33% nickel. However, nickel is not only expensive but also somewhat toxic, leaving significant room for improvement.

[0004] It can be seen that how to provide a sodium battery positive electrode material and its preparation method to improve battery energy density and cycle life while reducing raw material costs and alleviating the adverse effects of battery materials on the environment 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] The purpose of this application is to provide a multi-layered oxide sodium battery positive electrode material and its preparation method and application. By introducing low-cost Zn into the sodium battery positive electrode material to partially replace metallic Ni, the battery energy density and cycle life are improved while reducing the raw material cost, alleviating the adverse effects of battery materials on the environment, and facilitating large-scale promotion and application.

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

[0009] In the first aspect, the present application provides a multi-layered oxide sodium cathode material, wherein the chemical formula of the sodium cathode material is: NaNi x Zn y M z O2.

[0010] Among them, 0.1≤x≤0.3, 0<y≤0.2, 0.3≤z≤0.6, for example, x=0.1, 0.12, 0.14, 0.16, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28 or 0.3, y=0.02, 0.04, 0.06, 0.08, 0.1, 0.12, 0.14, 0.16, 0.18 or 0.2, z=0.3, 0.35, 0.4, 0.45, 0.5, 0.55 or 0.6, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0011] The M element is selected from any one or a combination of at least two of Ti, V, Cr, Mn, Fe, Co or Cu. Typical but non-limiting combinations include a combination of Ti and V, a combination of V and Cr, a combination of Cr and Mn, a combination of Mn and Fe, a combination of Fe and Co, a combination of Co and Cu, a combination of Ti, V and Cr, a combination of V, Cr and Mn, a combination of Cr, Mn and Fe, a combination of Mn, Fe and Co, or a combination of Fe, Co and Cu.

[0012] The present application introduces low-cost Zn into the sodium battery positive electrode material to partially replace the expensive and toxic metal Ni, thereby reducing the raw material cost and alleviating the adverse impact of battery materials on the environment; after Zn replaces the Ni lattice site, it can significantly reduce the transition metal interlayer spacing, increase the sodium interlayer spacing, and thus increase the diffusion rate of sodium ions, thereby improving the rate performance of the positive electrode material.

[0013] Furthermore, Zn in the cathode material can inhibit the formation of other impurities during the O3-O3' phase transition during charge and discharge, thereby improving the material's cycling performance. Although Zn is not electrochemically active, the addition of an appropriate amount of Zn does not reduce the material's capacity. It can also stimulate more active oxygen to undergo redox reactions, thereby increasing the material's reversible capacity.

[0014] In one embodiment, the molar ratio of Ni element to Zn element in the sodium positive electrode material is (2-3):1, for example, it can be 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1 or 3:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0015] In one embodiment, the average particle size of the sodium positive electrode material is 5-10 μm, for example, it can be 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm or 10 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0016] In a second aspect, the present application provides a method for preparing the sodium cathode material as described in the first aspect, the preparation method comprising the following steps:

[0017] (1) mixing nickel salt, zinc salt, M salt and deionized water to obtain a metal salt solution; the M element in the M salt is selected from any one or a combination of at least two of Ti, V, Cr, Mn, Fe, Co or Cu;

[0018] (2) preparing a precipitant solution and a double complexing agent solution independently, wherein the complexing agent in the double complexing agent solution includes a sodium salt of an organic acid containing a carboxyl group and an inorganic salt containing an ammonium group;

[0019] (3) adding the metal salt solution, the precipitant solution and the double complexing agent solution to the bottom liquid in parallel to carry out a co-precipitation reaction, and performing solid-liquid separation after aging treatment to obtain a sodium electrode precursor;

[0020] (4) Mixing the sodium source and the sodium electrode precursor and calcining them to obtain a multi-layered oxide sodium electrode positive electrode material.

[0021] Among them, step (1) and step (2) are performed in no particular order.

[0022] The preparation method provided in the present application uses a sodium salt of an organic acid with a carboxyl group and an inorganic salt containing an ammonium group as a double complexing agent, which effectively controls the complexing ability of the complexing agent for different metal ions, so that different metal ions can achieve a co-precipitation effect, thereby obtaining a positive electrode material precursor with uniform element distribution, increasing the utilization rate of active metal atoms in the positive electrode material, and contributing to the effective utilization of the capacity of the positive electrode material.

[0023] In one embodiment, the nickel salt, zinc salt and M 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.

[0024] In one embodiment, the total concentration of metal ions in the metal salt solution in step (1) is 0.5-5 mol / L, for example, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L or 5 mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0025] 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.

[0026] In one embodiment, the concentration of the precipitant solution in step (2) is 2-15 mol / L, for example, it can be 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, 10 mol / L, 11 mol / L, 12 mol / L, 13 mol / L, 14 mol / L or 15 mol / L, 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 carboxyl-containing organic acid sodium salt in step (2) comprises any one or a combination of at least two of sodium oxalate, sodium acetate, sodium citrate or EDTA. Typical but non-limiting combinations include a combination of sodium oxalate and sodium acetate, a combination of sodium acetate and sodium citrate, a combination of sodium citrate and EDTA, a combination of sodium oxalate, sodium acetate and sodium citrate, a combination of sodium acetate, sodium citrate and EDTA, or a combination of sodium oxalate, sodium acetate, sodium citrate and EDTA.

[0028] In one embodiment, the inorganic salt containing ammonium radicals in step (2) comprises any one or a combination of at least two of ammonium sulfate, ammonium bisulfate, ammonium chloride or ammonium nitrate. Typical but non-limiting combinations include a combination of ammonium sulfate and ammonium bisulfate, a combination of ammonium bisulfate and ammonium chloride, a combination of ammonium chloride and ammonium nitrate, a combination of ammonium sulfate, ammonium bisulfate and ammonium chloride, a combination of ammonium bisulfate, ammonium chloride and ammonium nitrate, or a combination of ammonium sulfate, ammonium bisulfate, ammonium chloride and ammonium nitrate.

[0029] In one embodiment, the concentrations of the two complexing agents in the dual complexing agent solution in step (2) are independently 0.2-2 mol / L, for example, 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L or 2 mol / L, but are not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0030] In one embodiment, the feed rate of the metal salt solution in step (3) is 4-100 L / h, for example, it can be 4 L / h, 5 L / h, 10 L / h, 15 L / h, 20 L / h, 25 L / h, 30 L / h, 35 L / h, 40 L / h, 45 L / h, 50 L / h, 55 L / h, 60 L / h, 65 L / h, 70 L / h, 75 L / h, 80 L / h, 85 L / h, 90 L / h, 95 L / h or 100 L / h, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0031] In one embodiment, the feed rate of the precipitant solution in step (3) is 1-20 L / h, for example, 1 L / h, 2 L / h, 3 L / h, 4 L / h, 5 L / h, 6 L / h, 7 L / h, 8 L / h, 9 L / h, 10 L / h, 11 L / h, 12 L / h, 13 L / h, 14 L / h, 15 L / h, 16 L / h, 17 L / h, 18 L / h, 19 L / h or 20 L / h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0032] In one embodiment, the feeding rate of the dual complexing agent solution in step (3) is 0.5-10 L / h, for example, it can be 0.5 L / h, 1 L / h, 1.5 L / h, 2 L / h, 2.5 L / h, 3 L / h, 3.5 L / h, 4 L / h, 4.5 L / h, 5 L / h, 5.5 L / h, 6 L / h, 6.5 L / h, 7 L / h, 7.5 L / h, 8 L / h, 8.5 L / h, 9 L / h, 9.5 L / h or 10 L / h, but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0033] In one embodiment, the pH value of the base solution in step (3) is 8-12, for example, it can be 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5 or 12, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0034] In one embodiment, the concentrations of the two complexing agents in the base solution of step (3) are independently 5-100 mmol / L, for example, 5 mmol / L, 10 mmol / L, 15 mmol / L, 20 mmol / L, 25 mmol / L, 30 mmol / L, 35 mmol / L, 40 mmol / L, 45 mmol / L, 50 mmol / L, 55 mmol / L, 60 mmol / L, 65 mmol / L, 70 mmol / L, 75 mmol / L, 80 mmol / L, 85 mmol / L, 90 mmol / L, 95 mmol / L or 100 mmol / L, but are not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0035] In one embodiment, the coprecipitation reaction in step (3) is carried out in a protective atmosphere, and the protective atmosphere comprises 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, more preferably nitrogen.

[0036] In one embodiment, the temperature of the coprecipitation reaction in step (3) is 20-70°C, for example, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C or 70°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0037] In one embodiment, the coprecipitation reaction time in step (3) is 50-100h, for example, it can be 50h, 55h, 60h, 65h, 70h, 75h, 80h, 85h, 90h, 95h or 100h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] In one embodiment, the aging treatment time in step (3) is 8-12 hours, for example, it can be 8 hours, 8.5 hours, 9 hours, 9.5 hours, 10 hours, 10.5 hours, 11 hours, 11.5 hours or 12 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] In one embodiment, the solid-liquid separation in step (3) comprises filtration and / or centrifugation.

[0040] In one embodiment, after the solid-liquid separation in step (3), the sodium electrolyte precursor is washed and dried in sequence.

[0041] In one embodiment, the washing is performed until the sodium precursor is neutral.

[0042] 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.

[0043] In one embodiment, the sodium source in step (4) comprises sodium carbonate and / or sodium bicarbonate.

[0044] In one embodiment, the sodium source in step (4) comprises sodium carbonate.

[0045] In one embodiment, the calcination treatment in step (4) is performed in an oxygen atmosphere.

[0046] In one embodiment, the temperature of the calcination treatment in step (4) is 800-1400°C, for example, it can be 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1150°C, 1200°C, 1250°C, 1300°C, 1350°C or 1400°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0047] In one embodiment, the calcination time in step (4) is 10-25 hours, for example, it can be 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours or 25 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0048] In one embodiment, after the calcination treatment in step (4), the sodium cathode material is ground and sieved in sequence.

[0049] As an optional technical solution of the second aspect of the present application, the preparation method comprises the following steps:

[0050] (1) mixing nickel salt, zinc salt, M salt and deionized water to obtain a metal salt solution with a total metal ion concentration of 0.5-5 mol / L; the nickel salt, zinc salt and M 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; the M element in the M salt is selected from any one of Ti, V, Cr, Mn, Fe, Co or Cu, or a combination of at least two thereof;

[0051] (2) preparing a precipitant solution and a double complexing agent solution respectively and independently; the precipitant in the precipitant solution comprises any one of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate or ammonium bicarbonate or a combination of at least two thereof, with a concentration of 2-15 mol / L; the complexing agent in the double complexing agent solution comprises a sodium salt of an organic acid containing a carboxyl group and an inorganic salt containing an ammonium radical, and the sodium salt of the organic acid containing a carboxyl group comprises any one of sodium oxalate, sodium acetate, sodium citrate or EDTA or a combination of at least two thereof, and the inorganic salt containing an ammonium radical comprises any one of ammonium sulfate, ammonium bisulfate, ammonium chloride or ammonium nitrate or a combination of at least two thereof, and the concentrations of the two complexing agents are respectively and independently 0.2-2 mol / L;

[0052] (3) adding a metal salt solution, a precipitant solution, and a double complexing agent solution to a base solution having a pH value of 8-12 in parallel, carrying out a coprecipitation reaction at 20-70° C. for 50-100 h in a nitrogen atmosphere, aging for 8-12 h, filtering and / or centrifuging, washing to neutrality, and drying at 50-150° C. to obtain a sodium electrode precursor; the feeding rate of the metal salt solution is 4-100 L / h, the feeding rate of the precipitant solution is 1-20 L / h, and the feeding rate of the double complexing agent solution is 0.5-10 L / h; the concentrations of the two complexing agents in the base solution are independently 5-100 mmol / L;

[0053] (4) Sodium carbonate and a sodium electrode precursor are mixed, calcined at 800-1400° C. for 10-25 h in an oxygen atmosphere, and then ground and sieved to obtain a multi-layered sodium oxide cathode material.

[0054] Among them, step (1) and step (2) are performed in no particular order.

[0055] In a third aspect, the present application provides a sodium ion battery, which comprises the sodium cathode material as described in the first aspect.

[0056] Compared with the prior art, this application has the following beneficial effects:

[0057] (1) This application introduces low-cost Zn into the sodium battery positive electrode material to partially replace the expensive and toxic metal Ni, thereby reducing the cost of raw materials and alleviating the adverse impact of battery materials on the environment; after Zn replaces the Ni lattice site, it can significantly reduce the transition metal interlayer spacing and increase the sodium interlayer spacing, thereby increasing the diffusion rate of sodium ions and improving the rate performance of the positive electrode material;

[0058] (2) The Zn element in the sodium cathode material provided by the present application can also inhibit the formation of other impurities during the O3-O3' phase transition during the charge and discharge process, thereby improving the cycle performance of the material; although Zn is not electrochemically active, the addition of an appropriate amount of Zn element does not reduce the capacity of the material, and can also stimulate more active oxygen to undergo redox reactions, thereby improving the reversible capacity of the material;

[0059] (3) The preparation method provided in the present application uses a sodium salt of an organic acid containing a carboxyl group and an inorganic salt containing an ammonium group as a double complexing agent, which effectively controls the complexing ability of the complexing agent for different metal ions, so that different metal ions can achieve a co-precipitation effect, thereby obtaining a positive electrode material precursor with uniform element distribution, increasing the utilization rate of active metal atoms in the positive electrode material, and contributing to the effective use of the capacity of the positive electrode material.

[0060] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0062] FIG1 is a SEM photograph of the sodium electrolyte precursor provided in Example 1;

[0063] FIG2 is an EPMA diagram of the Ni element in the cross section of the sodium electrode precursor provided in Example 1;

[0064] FIG3 is an EPMA diagram of the Zn element in the cross section of the sodium electrolyte precursor provided in Example 1. DETAILED DESCRIPTION

[0065] The technical solution of the present application is further described below through specific implementation methods. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations of the present application.

[0066] Example 1

[0067] This embodiment provides a multi-element layered sodium oxide cathode material and a preparation method thereof, the preparation method comprising the following steps:

[0068] (1) mixing nickel sulfate, zinc sulfate, ferrous sulfate, manganese sulfate, and deionized water to obtain a metal salt solution having a total metal ion concentration of 2 mol / L and a molar ratio of nickel, zinc, iron, and manganese of 2:1:4:3;

[0069] (2) preparing a sodium hydroxide solution with a concentration of 10 mol / L as a precipitant solution, and preparing a double complexing agent solution with a concentration of 0.6 mol / L sodium oxalate and a concentration of 0.4 mol / L ammonium sulfate;

[0070] (3) adding the metal salt solution, the precipitant solution and the double complexing agent solution in parallel to a base solution having a pH value of 11.6, a sodium oxalate concentration of 60 mmol / L and an ammonium sulfate concentration of 40 mmol / L, and carrying out a co-precipitation reaction at 45°C in a nitrogen atmosphere for 50 hours, aging for 12 hours, centrifuging, washing to neutrality, and drying at 130°C to obtain a sodium electrode precursor; the feed rate of the metal salt solution is 20 L / h, and the feed rates of the precipitant solution and the double complexing agent solution are adjusted to control the pH value of the reaction system between 10.8 and 11.0;

[0071] (4) Sodium carbonate and a sodium electrode precursor were mixed in a molar ratio of 1.03:1, calcined at 900° C. for 18 h in an oxygen atmosphere, and ground and sieved to obtain a multi-layered sodium oxide cathode material.

[0072] The chemical formula of the sodium cathode material obtained in this embodiment is: NaNi 0.20 Zn 0.10 Fe 0.40 Mn 0.30 O2.

[0073] The microscopic morphology of the sodium electrolyte precursor obtained in this example is shown in FIG1 . It can be seen that the sodium electrolyte precursor obtained in this example has good sphericity and uniform size, with an average particle size of 5.0 μm.

[0074] The EPMA images of Ni and Zn elements in the cross section of the sodium battery precursor obtained in this example are shown in FIG2 and FIG3 , which show that Ni and Zn elements are evenly distributed inside the sodium battery precursor particles.

[0075] Example 2

[0076] This embodiment provides a multi-element layered sodium oxide cathode material and a preparation method thereof, the preparation method comprising the following steps:

[0077] (1) mixing nickel nitrate, zinc nitrate, manganese nitrate and deionized water to obtain a metal salt solution having a total metal ion concentration of 2 mol / L and a nickel-zinc-manganese molar ratio of 3:1:6;

[0078] (2) preparing a 2 mol / L ammonium bicarbonate solution as a precipitant solution, and preparing a double complexing agent solution with a sodium citrate concentration of 0.5 mol / L and an ammonium sulfate concentration of 0.5 mol / L;

[0079] (3) adding the metal salt solution, the precipitant solution and the double complexing agent solution in parallel to a base solution having a pH value of 11.4, a sodium oxalate concentration of 50 mmol / L and an ammonium sulfate concentration of 50 mmol / L, and carrying out a co-precipitation reaction at 52° C. in a nitrogen atmosphere for 90 h, aging for 8 h, centrifuging, washing to neutrality, and drying at 150° C. to obtain a sodium electrode precursor; the feed rate of the metal salt solution is 40 L / h, and the feed rates of the precipitant solution and the double complexing agent solution are adjusted to control the pH value of the reaction system between 11.0 and 11.2;

[0080] (4) Sodium carbonate and a sodium electrode precursor were mixed in a molar ratio of 1.05:1, calcined at 1000° C. for 16 h in an oxygen atmosphere, and ground and sieved to obtain a multi-layered sodium oxide cathode material.

[0081] The chemical formula of the sodium cathode material obtained in this embodiment is: NaNi 0.30 Zn 0.10 Mn 0.60 O2.

[0082] The microstructure and element distribution of the sodium electrolyte precursor obtained in this embodiment are similar to those in Example 1, so they will not be described here.

[0083] Example 3

[0084] This embodiment provides a multi-element layered sodium oxide cathode material and a preparation method thereof. The preparation method is the same as that in Example 1 except that the nickel sulfate, zinc sulfate, ferrous sulfate, and manganese sulfate in step (1) are replaced by nickel chloride, zinc chloride, ferrous chloride, and manganese chloride, respectively. Therefore, they are not described in detail here.

[0085] The chemical formula of the sodium cathode material obtained in this embodiment is: NaNi 0.20 Zn 0.10 Fe 0.40 Mn 0.30 O2.

[0086] The microstructure and element distribution of the sodium electrolyte precursor obtained in this embodiment are similar to those in Example 1, so they will not be described here.

[0087] Comparative Example 1

[0088] This comparative example provides a sodium cathode material and a preparation method thereof. The preparation method comprises the following steps: (1) mixing nickel sulfate, ferrous sulfate, manganese sulfate, and deionized water to obtain a metal salt solution having a total metal ion concentration of 2 mol / L and a nickel-iron-manganese molar ratio of 2:4:3; and (2) the remaining steps and conditions are the same as those in Example 1 and are not described in detail herein.

[0089] Comparative Example 2

[0090] This comparative example provides a sodium cathode material and a preparation method thereof. The preparation method is the same as Example 1 except that the double complexing agent solution in step (2) and the base solution in step (3) are respectively replaced with sodium oxalate solutions of the same concentration. Therefore, the remaining steps and conditions are the same as those in Example 1 and are not described in detail here.

[0091] Comparative Example 3

[0092] This comparative example provides a sodium positive electrode material and a preparation method thereof. The preparation method is the same as in Example 1, except that step (1) is changed to: mixing nickel sulfate, ferrous sulfate, manganese sulfate and deionized water to obtain a metal salt solution with a total metal ion concentration of 2 mol / L and a nickel-iron-manganese molar ratio of 2:4:3; and the double complexing agent solution in step (2) and the base solution in step (3) are respectively changed to sodium oxalate solutions of the same concentration. The remaining steps and conditions are the same as in Example 1 and are not described in detail here.

[0093] Performance Testing

[0094] At 25°C, the sodium cathode materials obtained in Examples 1-3 and Comparative Examples 1-3 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 2.0-4.0 V and the discharge current density was 10 mA / g. The test results are shown in Table 1 below.

[0095] Table 1

[0096] It can be seen from Table 1 that the button batteries obtained from the multi-element layered sodium oxide positive electrode materials obtained in Examples 1-3 were charged and discharged at a current density of 10mA / g in the discharge range of 2.0-4.0V, and the gram capacity of the positive electrode material in the fifth cycle could reach more than 137.5mAh / g. However, the conventional zinc-free positive electrode material and the zinc-containing positive electrode material obtained by not using a double complexing agent to control the co-precipitation rate in the precursor preparation process were charged and discharged at a current density of 10mA / g in the discharge range of 2.0-4.0V, and the gram capacity of the positive electrode material in the fifth cycle did not reach 125mAh / g. This shows that the energy density of the sodium ion battery assembled from the zinc-containing multi-element layered sodium oxide positive electrode material prepared in this application is significantly better than that of the conventional sodium ion battery.

[0097] It can be seen that the present application introduces low-cost Zn into the sodium-based positive electrode material to partially replace the expensive and toxic metal Ni, thereby reducing the cost of raw materials and alleviating the adverse effects of battery materials on the environment; after Zn replaces the lattice site of Ni, it can significantly reduce the transition metal interlayer spacing, increase the sodium interlayer spacing, and thereby increase the diffusion rate of sodium ions, thereby improving the rate performance of the positive electrode material; the Zn element in the sodium-based positive electrode material can also inhibit the formation of other impurities during the O3-O3' phase transition during the charge and discharge process, thereby improving the cycle performance of the material; although Zn is not electrochemically active, the addition of an appropriate amount of Zn element does not reduce the capacity of the material, but can also stimulate more active oxygen to undergo redox reactions, thereby improving the reversible capacity of the material.

[0098] In addition, the preparation method provided in the present application uses a sodium salt of an organic acid containing a carboxyl group and an inorganic salt containing an ammonium group as a double complexing agent, which effectively controls the complexing ability of the complexing agent for different metal ions, so that different metal ions can achieve the effect of co-precipitation, thereby obtaining a positive electrode material precursor with uniform element distribution, increasing the utilization rate of active metal atoms in the positive electrode material, and contributing to the effective use of the capacity of the positive electrode material.

[0099] The applicant declares that the above is only a specific implementation method of the present application, but the protection scope of the present application is not limited thereto. Technical personnel in the relevant technical field should understand that any changes or substitutions that can be easily thought of by technical personnel in the relevant technical field within the technical scope disclosed in this application fall within the protection scope and disclosure scope of this application.

Claims

1. A multi-layered oxide sodium positive electrode material, the chemical formula of the sodium positive electrode material is: NaNi x Zn y M z O 2 ; in, 0.1≤x≤0.3, 0<y≤0.2, 0.3≤z≤0.6; the M element is selected from any one of Ti, V, Cr, Mn, Fe, Co and Cu, or a combination of at least two thereof.

2. The sodium positive electrode material according to claim 1, in, The molar ratio of Ni element to Zn element in the sodium positive electrode material is (2-3):1; Optionally, the average particle size of the sodium battery positive electrode material is 5-10 μm.

3. A method for preparing the sodium positive electrode material as claimed in claim 1 or 2, The following steps are involved: (1) mixing nickel salt, zinc salt, M salt and deionized water to obtain a metal salt solution; the M element in the M salt is selected from any one of Ti, V, Cr, Mn, Fe, Co and Cu, or a combination of at least two thereof; (2) preparing a precipitant solution and a dual complexing agent solution separately and independently, wherein the complexing agent in the dual complexing agent solution comprises a sodium salt of an organic acid containing a carboxyl group and an inorganic salt containing an ammonium group; (3) adding the metal salt solution, the precipitant solution and the double complexing agent solution to the bottom liquid in parallel to carry out a co-precipitation reaction, and performing solid-liquid separation after aging to obtain a sodium electrode precursor; (4) mixing a sodium source and a sodium electric precursor and performing a calcination treatment to obtain a multi-layered oxide sodium electric positive electrode material; There is no particular order in which steps (1) and (2) are performed.

4. The preparation method according to claim 3, in, The nickel salt, zinc salt and M salt in step (1) are independently any one of sulfate, nitrate, acetate or chloride of the corresponding metal ions or a combination of at least two thereof; Optionally, the total concentration of metal ions in the metal salt solution in step (1) is 0.5-5 mol / L.

5. The preparation method according to claim 3 or 4, in, The precipitant in the precipitant solution of step (2) comprises any one of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate or ammonium bicarbonate, or a combination of at least two thereof; Optionally, the concentration of the precipitant solution in step (2) is 2-15 mol / L; Optionally, the carboxyl-containing organic acid sodium salt in step (2) includes any one of sodium oxalate, sodium acetate, sodium citrate or EDTA, or a combination of at least two thereof; Optionally, the inorganic salt containing ammonium radicals in step (2) includes any one of ammonium sulfate, ammonium bisulfate, ammonium chloride or ammonium nitrate, or a combination of at least two thereof; Optionally, the concentrations of the two complexing agents in the dual complexing agent solution in step (2) are independently 0.2-2 mol / L.

6. The preparation method according to any one of claims 3 to 5, in, The feeding rate of the metal salt solution in step (3) is 4-100 L / h; Optionally, the feed rate of the precipitant solution in step (3) is 1-20 L / h; Optionally, the feeding rate of the dual complexing agent solution in step (3) is 0.5-10 L / h; Optionally, the pH value of the base solution in step (3) is 8-12; Optionally, the concentrations of the two complexing agents in the base solution of step (3) are independently 5-100 mmol / L.

7. The preparation method according to any one of claims 3 to 6, in, The coprecipitation reaction in step (3) is carried out in a protective atmosphere, and the protective atmosphere comprises any one or a combination of at least two of nitrogen, helium or argon, more preferably nitrogen; Optionally, the temperature of the coprecipitation reaction in step (3) is 20-70° C.; Optionally, the coprecipitation reaction time in step (3) is 50-100h; Optionally, the aging treatment time in step (3) is 8-12 hours; Optionally, the solid-liquid separation in step (3) comprises filtration and / or centrifugation; Optionally, after the solid-liquid separation in step (3), the sodium electrode precursor is washed and dried in sequence; Optionally, the washing is performed until the sodium-electric precursor is neutral; Optionally, the drying temperature is 50-150°C.

8. The preparation method according to any one of claims 3 to 7, in, The sodium source in step (4) includes sodium carbonate and / or sodium bicarbonate; Optionally, the calcination treatment in step (4) is carried out in an oxygen atmosphere; Optionally, the calcination temperature in step (4) is 800-1400°C; Optionally, the calcination time in step (4) is 10-25 hours; Optionally, after the calcination treatment in step (4), the sodium positive electrode material is ground and sieved in sequence.

9. The preparation method according to any one of claims 3 to 8, in, The sodium source in step (4) is sodium carbonate.

10. The preparation method according to any one of claims 3 to 9, in, The preparation method comprises the following steps: (1) mixing nickel salt, zinc salt, M salt and deionized water to obtain a metal salt solution with a total metal ion concentration of 0.5-5 mol / L; the nickel salt, zinc salt and M salt are independently any one of sulfate, nitrate, acetate or chloride of the corresponding metal ion or a combination of at least two thereof; the M element in the M salt is selected from any one of Ti, V, Cr, Mn, Fe, Co or Cu or a combination of at least two thereof; (2) preparing a precipitant solution and a double complexing agent solution separately and independently; the precipitant in the precipitant solution comprises any one of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate or ammonium bicarbonate or a combination of at least two thereof, and the concentration is 2-15 mol / L; the complexing agent in the double complexing agent solution comprises a sodium salt of an organic acid containing a carboxyl group and an inorganic salt containing an ammonium group, and the sodium salt of the organic acid containing a carboxyl group comprises any one of sodium oxalate, sodium acetate, sodium citrate or EDTA or a combination of at least two thereof, and the inorganic salt containing an ammonium group comprises any one of ammonium sulfate, ammonium bisulfate, ammonium chloride or ammonium nitrate or a combination of at least two thereof, and the concentrations of the two complexing agents are separately and independently 0.2-2 mol / L; (3) Add the metal salt solution, precipitant solution and double complexing agent solution in parallel to a solution having a pH value of 8-12. In a base liquid, a coprecipitation reaction is carried out at 20-70° C. for 50-100 hours in a nitrogen atmosphere, and after aging for 8-12 hours, the solution is filtered and / or centrifuged, washed to neutrality, and dried at 50-150° C. to obtain a sodium electric precursor; the feed rate of the metal salt solution is 4-100 L / h, the feed rate of the precipitant solution is 1-20 L / h, and the feed rate of the dual complexing agent solution is 0.5-10 L / h; the concentrations of the two complexing agents in the base liquid are independently 5-100 mmol / L; (4) mixing sodium carbonate and a sodium electrode precursor, calcining them in an oxygen atmosphere at 800-1400° C. for 10-25 h, grinding and sieving to obtain a multi-layered oxide sodium electrode positive electrode material; There is no particular order in which steps (1) and (2) are performed.

11. A sodium ion battery comprising the sodium positive electrode material according to claim 1 or 2.

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