Positive electrode active material and preparation method thereof, positive electrode sheet, sodium ion secondary battery and electrical equipment

Abstract

The present invention provides a positive electrode active material and a preparation method thereof, a positive electrode sheet, a sodium ion secondary battery and an electrical device, and specifically relates to the technical field of sodium ion batteries. The main phase of the positive electrode active material is composed of an O3-type layered oxide; the chemical formula of the layered oxide is Na x Ni a Fe b Mn c Zn d Cu f Mg h M z O2; wherein, a+b+c+d+f+h+z=1, 0.90≤x≤0.99, 0.20≤a≤0.25, 0.25≤b≤0.35, 0.25≤c≤0.45, 0.01≤d≤0.09, 0<f+h≤0.05, 0.005≤z≤0.035; M is composed of required Co and optional doping metal; the doping metal includes at least one of Ca, Ti, Zr, W, Ta, Mo, Sr and Nb.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion batteries, and in particular to a positive electrode active material and a preparation method thereof, a positive electrode sheet, a sodium ion secondary battery and electrical equipment. Background Art

[0002] Among layered oxide cathode materials for sodium-ion batteries, O3-type cathode materials boast high capacity compared to other sodium-ion battery cathode materials. In particular, O3-type cathodes with secondary spherical morphology offer advantages in rate performance. Currently, the primary voltage range for full-electrical evaluation of O3-type sodium battery cathode materials in battery cell factories is 1.5-4.0V. Within this range, the material's capacity performance is fully utilized while ensuring low cycle gas production in the battery cell, low gas production during high and low temperature storage, and stable low-temperature rate performance.

[0003] However, O3-type positive electrode materials have problems such as high cost and significant gas production in the battery cell, which can easily lead to safety hazards such as cycle water shortage and battery cell expansion.

[0004] 1. Due to the limitations of raw material processing, it is difficult to evenly distribute the doped metal / non-metallic elements. The main element raw materials are prone to agglomeration during the mixing process, and element segregation is prone to occur during the sintering process, resulting in uneven sodium ion intercalation and deintercalation channels, affecting material properties.

[0005] 2. The material obtained by sintering has serious melting phenomenon, and it is difficult to obtain particles with good sphericity and controllable primary particle size through subsequent crushing treatment, which greatly affects the wettability of the material in the electrolyte of the full battery.

[0006] 3. The surface alkalinity of the material is related to its Na embedding capacity. Adjusting the ratio of the main elements during sintering can easily lead to changes in the cationic potential, causing Na ions to remain on the surface of the secondary spheres. These ions then react with carbon dioxide and water in the air, affecting the slurry coating performance during full battery preparation. While traditional coating methods can address the surface alkalinity issue, they can also lead to decreased capacity and rate performance.

[0007] In view of this, the present invention is proposed. Summary of the Invention

[0008] The object of the present invention is to provide a positive electrode active material and a preparation method thereof and a sodium ion secondary battery, aiming to solve at least one of the above-mentioned technical problems in the prior art.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0010] The first aspect of the present invention provides a positive electrode active material, the main phase of which is composed of an O3 type layered oxide; the chemical formula of the layered oxide is Na x Ni a Feb Mn c Zn d Cu f Mg h M z O2; wherein, a+b+c+d+f+h+z=1, 0.90≤x≤0.99, 0.20≤a≤0.25, 0.25≤b≤0.35, 0.25≤c≤0.45, 0.01≤d≤0.09, 0<f+h≤0.05, 0.005≤z≤0.035; M is composed of required Co and optional doping metal; the doping metal includes at least one of Ca, Ti, Zr, W, Ta, Nb, Mo, Sr and Nb.

[0011] Furthermore, in the positive electrode active material, the number of atoms of each element satisfies: 0.94≤x≤0.99, 0.20≤a≤0.25, 0.25≤b≤0.35, 0.25≤c≤0.35, 0.01≤d≤0.09, 0.001≤f+h≤0.05, 0.005≤z≤0.035.

[0012] Furthermore, the chemical formula of the layered oxide satisfies at least one of the following conditions:

[0013] (1) The d, f, and h satisfy the following ranges: (0.1-fh)≥d and h≥f.

[0014] (2) The number of atoms of Co in M ​​is z1, and the number of atoms of other elements in M ​​is (z-z1); z1 satisfies the following range: z1≥z / 4 and z≥d / 5.

[0015] (3) The value of x satisfies x ≥ 1-d.

[0016] (4) When 0.8≤d / (f+h)≤1.2, x satisfies 0.95≤x≤0.98.

[0017] A second aspect of the present invention provides a method for preparing the positive electrode active material, comprising uniformly mixing a portion of a sodium source, a nickel source, an iron source, a manganese source, a zinc source, a copper source, a magnesium source, and a cobalt source to obtain a sintered precursor; performing a primary sintering on the sintered precursor, and then mixing the primary sintered product with the remaining sodium source and an optional doped metal precursor and performing a secondary sintering to obtain the positive electrode active material;

[0018] Among them, cobalt source and doping metal precursor are used as doping material M, sodium source, nickel source, iron source, manganese source, zinc source, copper source, magnesium source, doping material M is as follows: x Ni a Fe b Mn c Zn d Cuf Mg h M z The chemical formula of O2 is a+b+c+d+f+h+z=1, 0.90≤x≤0.99, 0.20≤a≤0.25, 0.25≤b≤0.35, 0.25≤c≤0.45, 0.01≤d≤0.09, 0<f+h≤0.05, 0.005≤z≤0.035.

[0019] Furthermore, the temperature of the primary sintering and the secondary sintering is independently 800-950°C, preferably 850-900°C.

[0020] Preferably, the time for the primary sintering and the secondary sintering is independently 12 to 24 hours, preferably 14 to 18 hours.

[0021] Preferably, the atmosphere for the primary sintering and the secondary sintering is air and / or oxygen, preferably air.

[0022] Furthermore, the sodium source is selected from at least one of anhydrous sodium carbonate, sodium carbonate monohydrate, sodium carbonate decahydrate, sodium bicarbonate and sodium sulfate, preferably at least one of anhydrous sodium carbonate, sodium bicarbonate and sodium sulfate.

[0023] Preferably, the cobalt source contains at least one of Co oxide, Co sulfide and Co nitride.

[0024] Preferably, the doped metal precursor includes at least one of an oxide containing a doped metal, a sulfide containing a doped metal, and a nitride containing a doped metal.

[0025] Preferably, the doped metal precursor is a nanomaterial.

[0026] Furthermore, the equipment used for mixing includes a ball mill, a three-dimensional mixer, a high-speed mixer or a VC mixer.

[0027] Preferably, the preparation method further includes a crushing and screening process after sintering.

[0028] Preferably, the crushing equipment includes a roller mill, a ball mill, a mortar mill or a jet mill.

[0029] A third aspect of the present invention provides a positive electrode plate, which includes the positive electrode active material described in the first aspect.

[0030] A fourth aspect of the present invention provides a sodium ion secondary battery comprising the positive electrode active material described in the first aspect.

[0031] A fifth aspect of the present invention provides an electrical device, which includes the above-mentioned sodium ion secondary battery.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects:

[0033] The positive electrode active material provided by the present invention can effectively improve the capacity and cycle performance of the positive electrode active material by regulating the elemental composition. Among them, the introduction of Zn promotes the phase change of the material to be advanced, thereby releasing more capacity, and then obtaining a higher capacity O3 type positive electrode material. In addition, the addition of Cu and Mg can not only suppress the risk of Zn migration and dissolution caused by the breakage of the Zn-O bond, but also regulate the phase change potential, so that the material remains stable during long cycles. The synergistic effect of Cu, Mg and Zn can also regulate the morphology of the material, making the primary particles of the secondary spheres thicker, larger and tighter, which is conducive to suppressing the gas production of the material during the cycle and high-temperature storage process, thereby improving the overcharge and over-discharge safety of the material in the full battery. At the same time, the introduction of Co and other doping elements, forming a combination in a certain proportion with Zn, can effectively solve the problem of decreased kinetic performance caused by Zn, and further optimize the comprehensive performance of the material.

[0034] The preparation method provided by the present invention utilizes staged sintering to evenly distribute the doping elements, reduce main element agglomeration and segregation, and optimize the uniformity of the sodium ion deintercalation channel. Secondary sintering further densifies the material structure, improves the sphericity of the particles and the controllability of the primary particle size, and significantly enhances the wettability of the electrolyte. Furthermore, by finely controlling the elemental composition, the surface cationic potential of the material is stabilized, residual Na ions are reduced, and surface alkalinity is lowered, thus avoiding the performance degradation caused by traditional coating methods.

[0035] The sodium ion secondary battery provided by the present invention, in view of the advantages of the above-mentioned positive electrode active material, has better electrochemical performance, reduces gas production, and improves battery safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 This is a scanning electron microscope image at a 1 μm scale obtained in Characterization Example 1;

[0038] Figure 2 This is a scanning electron microscope image at a 10 μm scale obtained in Characterization Example 1;

[0039] Figure 3 To characterize the XRD spectrum obtained in Example 2;

[0040] Figure 4 To characterize the dQ / dV spectrum obtained in Example 3;

[0041] Figure 5 The charge and discharge curves of button batteries at 0.2C and 1.0C. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0043] Hereinafter, the terms "including", "having" and their cognates, which may be used in various embodiments of the present invention, are intended only to indicate specific features, numbers, steps, operations, elements, components or combinations of the foregoing items, and should not be understood as first excluding the existence of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing items or the possibility of adding one or more features, numbers, steps, operations, elements, components or combinations of the foregoing items.

[0044] The first aspect of the present invention provides a positive electrode active material, the main phase of which is composed of an O3 type layered oxide; the chemical formula of the layered oxide is Na x Ni a Fe b Mn c Zn d Cu f Mg h M z O2; wherein, a+b+c+d+f+h+z=1, 0.90≤x≤0.99, 0.20≤a≤0.25, 0.25≤b≤0.35, 0.25≤c≤0.45, 0.01≤d≤0.09, 0<f+h≤0.05, 0.005≤z≤0.035; M is composed of required Co and optional doping metal; the doping metal includes at least one of Ca, Ti, Zr, W, Ta, Nb, Mo, Sr and Nb.

[0045] The positive electrode active material provided by the present invention can effectively improve the capacity and cycle stability of the positive electrode active material by regulating the elemental composition. Among them, the introduction of Zn promotes the phase change of the material to be advanced, thereby releasing more capacity, and then obtaining a higher capacity O3 type positive electrode material. In addition, the addition of Cu and Mg can not only suppress the risk of Zn migration and dissolution caused by the breakage of the Zn-O bond, but also regulate the phase change potential, so that the material remains stable during long cycles. The synergistic effect of Cu, Mg and Zn can also regulate the morphology of the material, making the primary particles of the secondary spheres thicker, larger and tighter, which is conducive to suppressing the gas production of the material during the cycle and high-temperature storage process, thereby improving the overcharge and over-discharge safety of the material in the full battery. At the same time, the introduction of Co and other doping elements, forming a combination in a certain proportion with Zn, can effectively solve the problem of decreased kinetic performance caused by Zn, and further optimize the comprehensive performance of the material.

[0046] As the number of elements in the material increases, the cationic potential will be affected to a certain extent. In particular, when the Ni content decreases, the overall sodium embedding ability of the material will decrease, and the capacity release will also decrease accordingly. In addition, the reduction in Ni content will cause residual sodium to adhere to the surface of the primary particles, thereby increasing the residual alkali content of the material. However, the introduction of Zn can compensate for this defect. Zn mainly occupies the Ni site, and due to the presence of Zn, the c-axis in the O3 structure will become larger, causing the O'3 phase to appear earlier, thereby releasing more capacity. This additional released capacity can compensate for the capacity lost due to the reduction of Ni.

[0047] However, Zn 2+ -O coordination bonds tend to be covalent (Zn(3d 10 ) only provides orbitals but not electrons), so the bond strength is weak. This may lead to the risk of Zn dissolution in Zn-containing materials during long cycles. In order to solve this problem, Mg, Cu and other elements are introduced into the positive electrode active material. The introduction of these elements can make the coordination bond length of Zn more uniform in structure, thereby effectively inhibiting the migration tendency of Zn and reducing its dissolution risk. At the same time, by optimizing the elemental ratio of Zn, Cu and Mg, the sodium content can be precisely controlled, which is of great significance for improving the overall performance of the material and controlling the amount of residual alkali.

[0048] In cathode materials, the ratio of Zn, Mg, and Cu significantly influences the premature phase transition potential (dQ / dV) of the O'3 phase. Taking the NFM111 system as an example, by adjusting the Zn, Cu, and Mg contents (denoted by d, f, and h, respectively), the phase transition potential can be controlled from 4.1V-4.2V to 3.8V-4.0V. Specifically, the phase transition potential can be manipulated by varying the d / (f+h) ratio.

[0049] When d decreases and f+h increases, the overall phase transition potential approaches 4.0V. Conversely, when d increases and f+h decreases, the O'3 phase transition potential approaches 3.8V. Notably, as the phase transition potential approaches 3.8V, the material's capacity increases accordingly. This method of manipulating the phase transition potential through element ratios provides an effective means for optimizing the material's electrochemical performance.

[0050] Typically, but not limiting, the chemical formula of the positive electrode active material may be, for example, Na 0.95 Ni 0.2 Fe 0.3 Mn 0.4 Zn 0.05 Cu 0.02 Mg 0.02 Co 0.01 O2、Na 0.97 Ni 0.21 Fe 0.295 Mn 0.39 Zn 0.04 Mg 0.03 Cu 0.01 Ca 0.005 Co 0.005 Ti 0.010 Zr 0.005 O2、Na 0.95 Ni 0.2 Fe 0.25 Mn 0.4 Zn 0.05 Cu 0.02 Mg 0.03 Co 0.02 W 0.01 Ta 0.02 O2、Na 0.92 Ni 0.22 Fe 0.30 Mn 0.38 Zn 0.04 Cu 0.01 Mg 0.04 Co 0.005 Nb 0.003 Mo 0.002 O2、Na 0.98 Ni 0.25 Fe 0.35 Mn 0.3 Zn 0.05 Cu 0.01 Mg 0.02 Co 0.01 Sr 0.01 O2、Na 0.93 Ni 0.2 1Fe 0.28 Mn 0.42 Zn 0.03 Cu 0.04Mg 0.01 Co 0.008 Ca 0.002 O2、Na 0.96 Ni 0.23 Fe 0.31 Mn 0.34 Zn 0.06 Cu 0.02 Mg 0.03 Co 0.008 Ta 0.001 Sr 0.001 O2.

[0051] Furthermore, in the positive electrode active material, the number of atoms of each element satisfies: 0.94≤x≤0.99, 0.20≤a≤0.25, 0.25≤b≤0.35, 0.25≤c≤0.35, 0.01≤d≤0.09, 0.01≤f+h≤0.05, 0.005≤z≤0.035.

[0052] Furthermore, the chemical formula of the layered oxide satisfies at least one of the following conditions:

[0053] (1) The d, f, and h satisfy the following ranges: (0.1-fh)≥d and h≥f.

[0054] (2) The number of atoms of Co in M ​​is z1, and the number of atoms of other elements in M ​​is (z-z1); z1 satisfies the following range: z1≥z / 4 and z≥d / 5.

[0055] (3) The value of x satisfies x ≥ 1-d.

[0056] (4) When 0.8≤d / (f+h)≤1.2, x satisfies 0.95≤x≤0.98.

[0057] When 0.8≤d / (f+h)≤1.2, x satisfies 0.95≤x≤0.98, achieving optimal electrochemical performance, residual alkaline, and overall battery performance. The material's morphology, capacity release, cycling stability, and O'3 phase transition location are determined by the proportional relationship between d, f, and h, while the material's rate capability is determined by both z and d.

[0058] A second aspect of the present invention provides a method for preparing the positive electrode active material, comprising uniformly mixing a portion of a sodium source, a nickel source, an iron source, a manganese source, a zinc source, a copper source, a magnesium source, and a cobalt source to obtain a sintered precursor; performing a primary sintering on the sintered precursor, and then mixing the primary sintered product with the remaining sodium source and an optional doped metal precursor and performing a secondary sintering to obtain the positive electrode active material;

[0059] Among them, cobalt source and doping metal precursor are used as doping material M, sodium source, nickel source, iron source, manganese source, zinc source, copper source, magnesium source, doping material M is as follows: x Ni a Fe b Mn c Zn d Cu f Mg h M z The chemical formula of O2 is a+b+c+d+f+h+z=1, 0.90≤x≤0.99, 0.20≤a≤0.25, 0.25≤b≤0.35, 0.25≤c≤0.45, 0.01≤d≤0.09, 0<f+h≤0.05, 0.005≤z≤0.035.

[0060] The preparation method provided by the present invention utilizes staged sintering to evenly distribute the doping elements, reduce main element agglomeration and segregation, and optimize the uniformity of the sodium ion deintercalation channel. Secondary sintering further densifies the material structure, improves the sphericity of the particles and the controllability of the primary particle size, and significantly enhances the wettability of the electrolyte. Furthermore, by finely controlling the elemental composition, the surface cationic potential of the material is stabilized, residual Na ions are reduced, and surface alkalinity is lowered, thus avoiding the performance degradation caused by traditional coating methods.

[0061] Furthermore, the portion of the sodium source accounts for 95-99% of the total mass of the sodium source.

[0062] Typically but not limitatively, the mass of the portion of the sodium source can be, for example, 95%, 96%, 97%, 98% or 99% of the total mass of the sodium source, or any value within the range of 95% to 99%.

[0063] Furthermore, the temperature of the primary sintering and the secondary sintering is independently 800-950°C, preferably 850-900°C.

[0064] Typically but not limitatively, the temperatures of the primary sintering and the secondary sintering are each independently, for example, 800°C, 820°C, 840°C, 860°C, 880°C, 900°C, 920°C or 950°C, or any value within the range of 800°C to 950°C; preferably, the temperatures of the primary sintering and the secondary sintering are each independently, for example, 850°C, 860°C, 870°C, 880°C, 890°C or 900°C, or any value within the range of 850°C to 900°C.

[0065] Preferably, the time for the primary sintering and the secondary sintering is independently 12 to 24 hours, preferably 14 to 18 hours.

[0066] Typically but not limitatively, the time for the primary sintering and the secondary sintering are each independently, for example, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h or 24 h, or any value within the range of 12 h to 24 h; further preferably, the time for the primary sintering and the secondary sintering are each independently, for example, 14 h, 15 h, 16 h, 17 h or 18 h, or any value within the range of 14 h to 18 h.

[0067] Preferably, the atmosphere for the primary sintering and the secondary sintering is air and / or oxygen, preferably air.

[0068] Furthermore, the sodium source includes at least one of anhydrous sodium carbonate, sodium carbonate monohydrate, sodium carbonate decahydrate, sodium bicarbonate and sodium sulfate, preferably at least one of anhydrous sodium carbonate, sodium bicarbonate and sodium sulfate.

[0069] Preferably, the cobalt source includes at least one of a Co-containing oxide, a Co-containing sulfide, and a Co-containing nitride.

[0070] Preferably, the doped metal precursor includes at least one of an oxide containing a doped metal, a sulfide containing a doped metal, and a nitride containing a doped metal.

[0071] Preferably, the doped metal precursor is a nanomaterial.

[0072] Furthermore, the equipment used for mixing includes a ball mill, a three-dimensional mixer, a high-speed mixer or a VC mixer.

[0073] Preferably, the preparation method further includes a crushing and screening process after sintering.

[0074] Preferably, the crushing equipment includes a roller mill, a ball mill, a mortar mill or a jet mill.

[0075] A third aspect of the present invention provides a sodium ion secondary battery comprising the positive electrode active material described in the first aspect.

[0076] The sodium ion secondary battery provided by the present invention, in view of the advantages of the above-mentioned positive electrode active material, has better electrochemical performance, reduces gas production, and improves battery safety.

[0077] The present invention also provides an electrical device, which includes the above-mentioned sodium ion secondary battery. The type of the electrical device is not limited. The electrical device can be an electric vehicle, a ship, an unmanned aerial vehicle, a fixed power supply, a portable power supply, etc.

[0078] The present invention is further illustrated below by specific examples and comparative examples. However, it should be understood that these examples are merely for the purpose of further explanation and should not be construed as limiting the present invention in any form. The raw materials used in the examples and comparative examples of the present invention, unless otherwise specified, were prepared under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used without manufacturer's indication are all commercially available conventional products.

[0079] Example 1

[0080] This embodiment provides a positive electrode active material, and the preparation method includes the following steps:

[0081] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=24.5:30:40:5.5 was prepared by co-precipitation method.

[0082] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, cobalt oxide, and calcium oxide according to the chemical formula Na 0.94 Ni 0.211 Fe 0.29 Mn 0.39 Zn 0.055 Cu 0.03 Mg 0.02 Ca 0.002 Co 0.002 Weigh O2 and mix well.

[0083] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0084] Finally, the primary sintered product is crushed and sieved, and then mixed with titanium oxide and zirconium oxide according to Na 0.94 Ni 0.205 Fe 0.29 Mn 0.39 Zn 0.055 Cu 0.03 Mg 0.02 Ca 0.002 Co 0.002 Ti 0.003 Zr 0.003 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0085] Example 2

[0086] This embodiment provides a positive electrode active material, and the preparation method includes the following steps:

[0087] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=24:31:40:5 was prepared by co-precipitation method.

[0088] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, cobalt oxide, and calcium oxide according to the chemical formula Na 0.94 Ni 0.224 Fe 0.29 Mn 0.392 Zn 0.05 Cu 0.01 Mg 0.03 Ca 0.002 Co 0.002 Weigh O2 and mix well.

[0089] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0090] Finally, the primary sintered product is crushed and sieved, and then mixed with titanium oxide and zirconium oxide according to Na 0.94 Ni 0.22 Fe 0.29 Mn 0.391 Zn 0.05 Cu 0.01 Mg 0.03 Ca 0.002 Co 0.002 Ti 0.003 Zr 0.002 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0091] Example 3

[0092] This embodiment provides a positive electrode active material, and the preparation method includes the following steps:

[0093] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=23.5:31:40:5.5 was prepared by co-precipitation method.

[0094] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, cobalt oxide, and calcium oxide according to the chemical formula Na 0.94 Ni 0.205 Fe 0.29 Mn 0.39 Zn 0.055 Cu 0.03 Mg 0.02 Ca 0.005 Co 0.005 Weigh O2 and mix well.

[0095] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0096] Finally, the primary sintered product is crushed and sieved, and then mixed with titanium oxide and zirconium oxide according to Na 0.94 Ni 0.20 Fe 0.29 Mn 0.385 Zn 0.055 Cu 0.03 Mg 0.02 Ca 0.005 Co 0.005 Ti 0.005 Zr 0.005 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0097] Example 4

[0098] This embodiment provides a positive electrode active material, and the preparation method includes the following steps:

[0099] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=23.5:31:40:5.5 was prepared by co-precipitation method.

[0100] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, cobalt oxide, and calcium oxide according to the chemical formula Na 0.97 Ni 0.211 Fe 0.29 Mn 0.39 Zn 0.055 Cu 0.03 Mg 0.02 Ca 0.002 Co 0.002 Weigh O2 and mix well.

[0101] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0102] Finally, the primary sintered product is crushed and sieved, and then mixed with titanium oxide and zirconium oxide according to Na 0.99 Ni 0.21 Fe 0.29 Mn 0.385 Zn 0.055 Cu 0.03 Mg0.02 Ca 0.002 Co 0.002 Ti 0.003 Zr 0.003 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0103] Example 5

[0104] This embodiment provides a positive electrode active material, and the preparation method includes the following steps:

[0105] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=24:31:40:5 was prepared by co-precipitation method.

[0106] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, cobalt oxide, and calcium oxide according to the chemical formula Na 0.94 Ni 0.22 Fe 0.29 Mn 0.39 Zn 0.05 Cu 0.01 Mg 0.03 Ca 0.005 Co 0.005 Weigh O2 and mix well.

[0107] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0108] Finally, the primary sintered product is crushed and sieved, and then mixed with titanium oxide and zirconium oxide according to Na 0.94 Ni 0.21 Fe 0.29 Mn 0.39 Zn 0.05 Cu 0.01 Mg 0.03 Ca 0.005 Co 0.005 Ti 0.005 Zr 0.005 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0109] Example 6

[0110] This embodiment provides a positive electrode active material, and the preparation method includes the following steps:

[0111] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=24:31:40:5 was prepared by co-precipitation method.

[0112] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, calcium oxide, and cobalt oxide according to the chemical formula Na 0.93 Ni 0.235 Fe 0.295 Mn 0.378 Zn 0.04 Cu 0.01 Mg 0.03 Ca 0.004 Co 0.008 Weigh O2 and mix well.

[0113] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0114] Finally, the primary sintered product is crushed and sieved, and then mixed with titanium oxide, molybdenum oxide, copper oxide, and Na 0.93 Ni 0.225 Fe 0.295 Mn 0.375 Zn 0.04 Cu 0.013 Mg 0.03 Co 0.008 Ti 0.005 Ca 0.004 Mo 0.005 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0115] Example 7

[0116] This embodiment provides a positive electrode active material, and the preparation method includes the following steps:

[0117] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=23:31:40:6 was prepared by co-precipitation method.

[0118] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, calcium oxide, and cobalt oxide according to the chemical formula Na 0.95 Ni 0.225 Fe 0.30 Mn 0.39 Zn 0.06 Cu 0.005 Mg 0.01 Ca 0.005 Co 0.005 Weigh O2 and mix well.

[0119] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 12 hours, the temperature was lowered to 850°C and kept at this temperature for 6 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0120] Finally, the primary sintered product is crushed and sieved, and then mixed with sodium carbonate, zirconium oxide, and titanium oxide according to Na 0.97 Ni 0.21 Fe 0.295 Mn 0.39 Zn 0.06 Cu 0.005 Mg 0.01 Co 0.01 Ca 0.005 Ti 0.01 Zr 0.005 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0121] Example 8

[0122] This embodiment provides a positive electrode active material, and the preparation method includes the following steps:

[0123] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=23:31:40:6 was prepared by co-precipitation method.

[0124] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, calcium oxide, and cobalt oxide according to the chemical formula Na 0.95 Ni 0.22 Fe 0.30 Mn 0.395 Zn 0.05 Cu 0.009 Mg 0.015 Ca 0.005 Co 0.006 Weigh O2 and mix well.

[0125] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0126] Finally, the primary sintered product is crushed and sieved, and then mixed with sodium carbonate, molybdenum oxide, and titanium oxide according to Na 0.97 Ni 0.21 Fe 0.295 Mn 0.39 Zn 0.05 Cu 0.009 Mg0.015 Ca 0.005 Co 0.006 Ti 0.015 Mo 0.005 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0127] Example 9

[0128] This embodiment provides a positive electrode active material, and the preparation method includes the following steps:

[0129] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=24:31:40:5 was prepared by co-precipitation method.

[0130] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, cobalt oxide, and calcium oxide according to the chemical formula Na 0.96 Ni 0.225 Fe 0.29 Mn 0.39 Zn 0.05 Cu 0.01 Mg 0.03 Ca 0.003 Co 0.002 Weigh O2 and mix well.

[0131] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0132] Finally, the primary sintered product is crushed and sieved, and then mixed with titanium oxide and zirconium oxide according to Na 0.96 Ni 0.22 Fe 0.29 Mn 0.39 Zn 0.05 Cu 0.01 Mg 0.03 Ca 0.003 Co 0.002 Ti 0.003 Zr 0.002 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0133] Example 10

[0134] This embodiment provides a positive electrode active material, and the preparation method includes the following steps:

[0135] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=23:31:40:6 was prepared by co-precipitation method.

[0136] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, calcium oxide, and cobalt oxide according to the chemical formula Na 0.95 Ni 0.225 Fe 0.30 Mn 0.39 Zn 0.06 Cu 0.009 Mg 0.006 Ca 0.005 Co 0.005 Weigh O2 and mix well.

[0137] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 12 hours, the temperature was lowered to 850°C and kept at this temperature for 6 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0138] Finally, the primary sintered product is crushed and sieved, and then mixed with sodium carbonate, zirconium oxide, and titanium oxide according to Na 0.97 Ni 0.21 Fe 0.295 Mn 0.39 Zn 0.06 Cu 0.009 Mg 0.006 Co 0.01 Ca 0.005 Ti 0.01 Zr 0.005 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0139] Example 11

[0140] This embodiment provides a positive electrode active material, and the preparation method includes the following steps:

[0141] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=24:32:40:4 was prepared by co-precipitation method.

[0142] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, calcium oxide, and cobalt oxide according to the chemical formula Na 0.95 Ni 0.21 Fe 0.295 Mn 0.38 Zn 0.06 Cu 0.015 Mg 0.03 Ca 0.005 Co 0.005 Weigh O2 and mix well.

[0143] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 12 hours, the temperature was lowered to 850°C and kept at this temperature for 6 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0144] Finally, the primary sintered product is crushed and sieved, and then mixed with sodium carbonate, zirconium oxide, and titanium oxide according to Na 0.97 Ni 0.20 Fe 0.29 Mn 0.375 Zn 0.06 Cu 0.015 Mg 0.03 Co 0.01 Ca 0.005 Ti 0.01 Zr 0.005 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0145] Example 12

[0146] This embodiment provides a positive electrode active material, and the preparation method includes the following steps:

[0147] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=23:31:40:6 was prepared by co-precipitation method.

[0148] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, calcium oxide, and cobalt oxide according to the chemical formula Na 0.95 Ni 0.225 Fe 0.30 Mn 0.392 Zn 0.05 Cu 0.009 Mg 0.015 Ca 0.005 Co 0.004 Weigh O2 and mix well.

[0149] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0150] Finally, the primary sintered product is crushed and sieved, and then mixed with sodium carbonate, molybdenum oxide, and titanium oxide according to Na 0.97 Ni 0.221 Fe 0.298 Mn 0.398 Zn 0.05 Cu 0.009 Mg0.015 Ca 0.002 Co 0.004 Ti 0.002 Mo 0.001 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0151] Example 13

[0152] This embodiment provides a positive electrode active material, and the preparation method includes the following steps:

[0153] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=25:29:38:8 was prepared by co-precipitation method.

[0154] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, cobalt oxide, calcium oxide, and the chemical formula Na 0.95 Ni 0.205 Fe 0.27 Mn 0.375 Zn 0.08 Cu 0.015 Mg 0.03 Ca 0.005 Co 0.02 Weigh O2 and mix well.

[0155] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0156] Finally, the primary sintered product is crushed and sieved, and then mixed with titanium oxide, zirconium oxide, and Na 0.95 Ni 0.20 Fe 0.27 Mn 0.37 5Zn 0.08 Cu 0.005 Mg 0.03 Ca 0.005 Co 0.02 Ti 0.005 Zr 0.005 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0157] Example 14

[0158] This embodiment provides a positive electrode active material, and the preparation method includes the following steps:

[0159] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=23:31:40:6 was prepared by co-precipitation method.

[0160] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, calcium oxide, and cobalt oxide according to the chemical formula Na 0.95 Ni 0.218 Fe 0.30 Mn 0.393 Zn 0.05 Cu 0.009 Mg 0.015 Ca 0.005 Co 0.01 Weigh O2 and mix well.

[0161] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0162] Finally, the primary sintered product is crushed and sieved, and then mixed with sodium carbonate, molybdenum oxide, and titanium oxide according to Na 0.97 Ni 0.21 Fe 0.295 Mn 0.39 Zn 0.05 Cu 0.009 Mg 0.015 Ca 0.005 Co 0.01 Ti 0.011 Mo 0.005 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0163] Example 15

[0164] This embodiment provides a positive electrode active material, and the preparation method includes the following steps:

[0165] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=25:29:38:8 was prepared by co-precipitation method.

[0166] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, calcium oxide, and cobalt oxide according to the chemical formula Na 0.95 Ni 0.215 Fe 0.29 Mn 0.37 Zn 0.08 Cu 0.005 Mg 0.015 Ca 0.005 Co 0.02 Weigh O2 and mix well.

[0167] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0168] Finally, the primary sintered product is crushed and sieved, and then mixed with titanium oxide, zirconium oxide, and Na 0.95 Ni 0.21 Fe 0.29 Mn 0.36 5Zn 0.08 Cu 0.005 Mg 0.015 Co 0.02 Ti 0.005 Ca 0.005 Zr 0.005 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0169] Example 16

[0170] This embodiment provides a positive electrode active material, and the preparation method includes the following steps:

[0171] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=26:33:40:1 was prepared by co-precipitation method.

[0172] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, calcium oxide, and cobalt oxide according to the chemical formula Na 0.96 Ni 0.245 Fe 0.33 Mn 0.395 Zn 0.01 Cu 0.004 Mg 0.006 Ca 0.005 Co 0.005 Weigh O2 and mix well.

[0173] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0174] Finally, the primary sintered product is crushed and sieved, and then mixed with sodium carbonate, titanium oxide, zirconium oxide, and Na 0.99 Ni 0.24 Fe 0.33 Mn 0.39 Zn 0.01 Cu 0.004 Mg0.006 Co 0.005 Ti 0.008 Ca 0.005 Zr 0.002 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0175] Example 17

[0176] This embodiment provides a positive electrode active material, and the preparation method includes the following steps:

[0177] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=24:30:40:6 was prepared by co-precipitation method.

[0178] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, and cobalt oxide according to the chemical formula Na 0.95 Ni 0.22 Fe 0.30 Mn 0.379 Zn 0.05 Cu 0.01 Mg 0.035 Co 0.006 Weigh O2 and mix well.

[0179] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0180] Finally, the primary sintered product is crushed and sieved, and then mixed with titanium oxide and tantalum oxide according to Na 0.96 Ni 0.215 Fe 0.295 Mn 0.375 Zn 0.05 Cu 0.01 Mg 0.035 Co 0.006 Ti 0.01 Ta 0.004 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0181] Example 18

[0182] This embodiment provides a positive electrode active material, and the preparation method includes the following steps:

[0183] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=24:33:40:3 was prepared by co-precipitation method.

[0184] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, and cobalt oxide according to the chemical formula Na 0.95 Ni 0.225 Fe 0.313 Mn 0.379 Zn 0.03 Cu 0.01 Mg 0.03 Ca 0.005 Co 0.008 Weigh O2 and mix well.

[0185] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0186] Finally, the primary sintered product is crushed and sieved, and then mixed with titanium oxide, zirconium oxide, calcium oxide, and Na 0.95 Ni 0.225 Fe 0.295 Mn 0.375 Zn 0.03 Cu 0.015 Mg 0.035 Co 0.008 Ti 0.007 Ca 0.005 Zr 0.005 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0187] Example 19

[0188] This embodiment provides a positive electrode active material, and the preparation method includes the following steps:

[0189] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=24:33:40:3 was prepared by co-precipitation method.

[0190] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, calcium oxide, and cobalt oxide according to the chemical formula Na 0.95 Ni 0.225 Fe 0.31 Mn 0.39 Zn 0.03 Cu 0.008 Mg 0.025 Ca 0.005 Co 0.007 Weigh O2 and mix well.

[0191] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0192] Finally, the primary sintered product is crushed and sieved, and then mixed with sodium carbonate, titanium oxide, zirconium oxide, and Na 0.98 Ni 0.22 Fe 0.305 Mn 0.385 Zn 0.03 Cu 0.008 Mg 0.025 Co 0.007 Ti 0.01 Ca 0.005 Zr 0.005 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0193] Example 20

[0194] This embodiment provides a positive electrode active material, and the preparation method includes the following steps:

[0195] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=24:32:40:4 was prepared by co-precipitation method.

[0196] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, calcium oxide, and cobalt oxide according to the chemical formula Na 0.95 Ni 0.22 Fe 0.298 Mn 0.39 Zn 0.04 Mg 0.03 Cu 0.01 Ca 0.005 Co 0.007 Weigh O2 and mix well.

[0197] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 12 hours, the temperature was lowered to 850°C and kept at this temperature for 6 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0198] Finally, the primary sintered product is crushed and sieved, and then mixed with sodium carbonate, zirconium oxide, and titanium oxide according to Na 0.97 Ni 0.21 Fe 0.295 Mn 0.39 Zn 0.04 Cu 0.01 Mg 0.03 Ca0.005 Co 0.007 Ti 0.008 Zr 0.005 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0199] Comparative Example 1

[0200] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=24:31:40:5 was prepared by co-precipitation method.

[0201] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, and calcium oxide according to the chemical formula Na 0.95 Ni 0.22 Fe 0.30 Mn 0.395 Zn 0.04 Cu 0.01 Mg 0.03 Ca 0.005 Weigh O2 and mix well.

[0202] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0203] Finally, the primary sintered product is crushed and sieved, and then mixed with sodium carbonate, titanium oxide, zirconium oxide, and Na 0.97 Ni 0.217 Fe 0.295 Mn 0.39 Zn 0.04 Cu 0.01 Mg 0.03 Ca 0.005 Ti 0.008 Zr 0.005 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0204] Comparative Example 2

[0205] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=25:33.5:41:0.5 was prepared by co-precipitation method.

[0206] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, cobalt oxide, and calcium oxide according to the chemical formula Na 0.95 Ni 0.24 Fe 0.31 Mn 0.393 Zn0.005 Cu 0.01 Mg 0.03 Ca 0.005 Co 0.007 Weigh O2 and mix well.

[0207] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0208] Finally, the primary sintered product is crushed and sieved, and then mixed with sodium carbonate, titanium oxide, zirconium oxide, and Na 0.97 Ni 0.235 Fe 0.30 Mn 0.395 Zn 0.005 Cu 0.01 Mg 0.03 Ca 0.005 Co 0.007 Ti 0.008 Zr 0.005 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0209] Comparative Example 3

[0210] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=22.5:30:38:9.5 was prepared by co-precipitation method.

[0211] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, cobalt oxide, and calcium oxide according to the chemical formula Na 0.95 Ni 0.21 Fe 0.29 Mn 0.373 Zn 0.095 Cu 0.005 Mg 0.015 Ca 0.005 Co 0.007 Weigh O2 and mix well.

[0212] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0213] Finally, the primary sintered product is crushed and sieved, and then mixed with sodium carbonate, titanium oxide, zirconium oxide, and Na 0.97 Ni 0.20 Fe 0.29 Mn 0.37Zn 0.095 Cu 0.005 Mg 0.015 Ca 0.005 Co 0.007 Ti 0.008 Zr 0.005 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0214] Comparative Example 4

[0215] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=25:32:40:3 was prepared by co-precipitation method.

[0216] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, cobalt oxide, and calcium oxide according to the chemical formula Na 0.95 Ni 0.22 Fe 0.29 Mn 0.393 Zn 0.03 Cu 0.015 Mg 0.04 Ca 0.005 Co 0.007 Weigh O2 and mix well.

[0217] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0218] Finally, the primary sintered product is crushed and sieved, and then mixed with sodium carbonate, titanium oxide, zirconium oxide, and Na 0.97 Ni 0.21 Fe 0.29 Mn 0.39 Zn 0.03 Cu 0.015 Mg 0.04 Ca 0.005 Co 0.007 Ti 0.008 Zr 0.005 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0219] Comparative Example 5

[0220] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=23:31:40:6 was prepared by co-precipitation method.

[0221] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, cobalt oxide, and calcium oxide according to the chemical formula Na 0.95 Ni 0.211 Fe 0.296 Mn 0.39 Zn 0.06 Cu 0.01 Mg 0.03 Co 0.003 Weigh O2 and mix well.

[0222] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0223] Finally, the primary sintered product is crushed and sieved, and then mixed with sodium carbonate and titanium oxide according to Na 0.97 Ni 0.21 Fe 0.296 Mn 0.39 Zn 0.06 Cu 0.01 Mg 0.03 Co 0.003 Ti 0.001 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0224] Comparative Example 6

[0225] First, a spherical hydroxide precursor with Ni:Fe:Mn:Zn=24:32:40:4 was prepared by co-precipitation method.

[0226] Secondly, the spherical hydroxide precursor is mixed with sodium carbonate, magnesium oxide, copper oxide, cobalt oxide, and calcium oxide according to the chemical formula Na 0.95 Ni 0.24 Fe 0.29 Mn 0.395 Zn 0.03 Cu 0.01 Mg 0.02 Ca 0.005 Co 0.01 Weigh O2 and mix well.

[0227] Again, the above materials were placed in a box furnace for primary sintering, the temperature was raised to 900°C at a rate of 5°C / min, kept at this temperature for 14 hours, the temperature was lowered to 850°C and kept at this temperature for 4 hours, and then quickly cooled to room temperature to obtain a primary sintered product.

[0228] Finally, the primary sintered product is crushed and sieved, and then mixed with sodium carbonate, titanium oxide, zirconium oxide, and Na0.97 Ni 0.21 Fe 0.29 Mn 0.39 Zn 0.04 Cu 0.01 Mg 0.02 Ca 0.005 Co 0.01 Ti 0.015 Zr 0.005 The mixture was mixed with O2, heated to 850°C at a rate of 5°C / min, kept at 850°C for 6h, and rapidly cooled to obtain a positive electrode active material.

[0229] Characterization Example 1

[0230] The positive electrode active material prepared in Example 1 was analyzed by scanning electron microscopy (SEM), and the Figure 1 and Figure 2 Two electron microscope images.

[0231] from Figure 1 The primary particles of this material exhibit an elongated morphology, with lengths ranging from 2-3 μm and thicknesses of 0.2-0.5 μm. During the sintering process, zinc primarily acts as a flux. Granular and rod-like attachments are visible on the surface of the material; these characteristic features originate from the coating formed by the nano-oxide added during the secondary sintering process. The secondary particles exhibit a regular spherical morphology, with a particle size distribution concentrated in the 8.8-9.2 μm range. The primary particles are densely packed, with small gaps between them.

[0232] from Figure 2 It can be seen that the secondary particles of the material are regular spherical, the particle size distribution is uniform, there is less adhesion between particles, and the overall dispersion is good.

[0233] Characterization Example 2

[0234] The XRD spectrum of the positive electrode active material prepared in Example 1 is as follows: Figure 3 shown.

[0235] from Figure 3 It can be seen that the diffraction positions of the 003 and 104 peaks are consistent with those of typical O3-phase sodium layered cathode materials, indicating that the material has a standard O3-type crystal structure. In addition, the high intensity of the 003 diffraction peak is mainly attributed to the fluxing effect of elements such as Zn, Cu, and Mg, which promotes the material's quasi-single crystal growth, increases the primary particle size, and significantly improves the material's full-cell gas production performance.

[0236] Characterization Example 3

[0237] The positive electrode active material prepared in Example 1 was tested by a button cell, and the obtained dQ / Dv curve was as follows: Figure 4 shown.

[0238] from Figure 4 It can be seen that when d / (f+h)=1 in the materials Zn, Mg, and Cu, the O'3 phase transition occurs near 3.95V.

[0239] Test Example 1

[0240] The materials obtained in the examples and comparative examples were subjected to particle size testing, tap density testing, specific surface area testing, pH testing, residual alkali content testing, and water content testing.

[0241] Particle size distribution: Determined by laser diffraction method (D50). The test standard is based on GB / T 19077-2016 “Particle size analysis - laser diffraction method”.

[0242] Tap density: Tested in accordance with GB / T 5162-2006 / ISO 3953:1993 "Metal powders - Determination of tap density".

[0243] Specific surface area: Determined by gas adsorption BET method (volumetric method). The test standard refers to GB / T 19587-2017 "Determination of specific surface area of ​​solid substances by gas adsorption BET method".

[0244] Water content: Determined in accordance with GB / T 6283-2008 “Determination of water content in chemical products – Karl Fischer method (general method)”.

[0245] pH value: The detection method refers to GB / T 5211.6-2020 "General test methods for pigments and extenders".

[0246] Residual alkali content: The test method refers to GB / T 41704-2022, "Lithium-ion battery positive electrode material test method - Determination of magnetic foreign matter content and residual alkali content," replacing the test medium with ethylene glycol. The resulting data are recorded in Table 1.

[0247] Table 1

[0248]

[0249] It can be seen from Table 1 that when the proportion of Zn or D in the system increases, its bulk sodium embedding ability will weaken, and the OH in the overall bulk residual base will - and CO3 2-The content of Mg and Cu increases, so the ratio and content of Mg and Cu play a significant role in regulating the residual alkali. When 0.8 ≤ d / (f+h) ≤ 1.2 and the sodium content is between 0.95 and 0.98, the residual alkali is effectively optimized and the material's performance is maximized. Of course, reducing the sodium content, such as to less than 0.95, can effectively reduce the residual alkali, but the overall electrochemical performance, particularly the capacity, decreases significantly. The sintered particle size (D50) of the material ranges from 0.88 to 0.91 μm, and is significantly influenced by the precursor particle size and the presence of Cu, Mg, and Zn in the bulk phase. These three elements generally have a fluxing effect, which increases with their higher content. The tap density of the material is significantly affected by particle size and, to a lesser extent, Cu, and is generally between 1.8 and 2.0 g / cc. The pH and moisture content are related to the bulk stability of the material, primarily through the regulation of the Zn, Cu, and Mg ratios. Excellent performance is achieved when the ratio is 0.8 ≤ d / (f+h) ≤ 1.2.

[0250] Test Example 2

[0251] The positive electrode active material of the embodiment and the comparative example was mixed with PVDF and conductive carbon in a mass ratio of 90:5:5 or 8:1:1, dispersed in NMP solvent, and coated on an aluminum foil current collector and dried to form a positive electrode sheet. The positive electrode sheet, sodium sheet, glass fiber separator, gasket, reed, and NaPF6-DIGLYME electrolyte were then made into a button battery according to the standard button battery assembly operating procedure. The button batteries prepared above were subjected to a button-cycle test and a button-rate performance test using a blue electric test cabinet. The data obtained are shown in Table 2 below.

[0252] Table 2

[0253]

[0254] Comparing Example 1 and Comparative Examples 1-6, it can be seen that when Co is not doped or any one of d, f+h, and z does not meet the specific range requirements or, the capacity, rate performance, and cycle performance of the material are poor. Among them, it can be seen from Comparative Example 1 that when Co is not doped, the kinetics of the material deteriorate after the introduction of Zn, which will cause the rate performance and cycle performance of the material to deteriorate significantly, and the sodium ion deintercalation ability will deteriorate. It can be seen from Comparative Examples 2-3 that when d<0.01, the capacity of the material is low, the average voltage is also low, and the closer the dQ / dV peak position of the material is to 4.0V, that is, the cut-off potential of charging, it is not conducive to the optimal release of the material capacity. When d>0.09, the closer the dQ / dV peak position of the material is to 3.8V, the premature phase change can bring considerable capacity, but a complete phase change will lead to the introduction of a partial irreversible phase change, which has a greater impact on the cycle and structural stability of the material. At the same time, too much Zn leads to worse dynamic performance of its structure, worse rate performance, and decreased overall sodium embedding ability of the structure, which ultimately leads to serious residual alkali in the material and element segregation. As can be seen from Comparative Example 4, when f+h>0.05, the introduction of too much Cu and Mg will hinder the performance of the capacity, and at the same time, it will cause the material to have too high a crystallinity, and the material will grow towards a single crystal-like form, causing the grain boundaries of the primary particles of the material to become larger, which is easy to crack during the cycle process, causing cycle attenuation problems. As can be seen from Comparative Examples 5-6, when z<0.005, the rate performance and residual alkali improvement effect of the material are poor. When z>0.035, the rate performance of the material is greatly improved due to the increase in Co content. However, due to the large amount of other elements introduced, part of the other elements enter the bulk phase and part of them serve as a coating, causing the surface accumulation to be too thick, which will hinder the deintercalation of sodium ions, resulting in a decrease in the capacity and cycle performance of the material.

[0255] By comparing Example 1 and Example 2, it can be seen that on the basis of 0.01≤d≤0.09, 0<f+h≤0.05, 0.005≤z≤0.035, further controlling (0.1-fh)≥d and h≥f can effectively improve the kinetic degradation problem caused by the introduction of Zn, while improving the material stability. In addition, the overall sodium embedding ability of the material is improved and the residual alkali content is reduced.

[0256] Furthermore, by comparing Examples 10, 11, 14 and 15, it can be seen that when (0.1-fh)<d or h<f, excessive Zn brings about an improvement in capacity, but the excessive Zn content of the material leads to serious deterioration of kinetics, deterioration of cycles, and high residual alkali. Even if elements such as Cu and Mg are introduced to improve the structure, the effects of overall structural performance optimization and residual alkali optimization brought about by the introduction of Zn cannot be fully utilized. In addition, when the content of Cu is greater than that of Mg, the crystallinity of the material crystal is too high, thereby hindering the better performance of the column effect of Mg. This will also cause changes in the sodium ion channel, thereby causing a decrease in capacity, cycle performance and rate performance.

[0257] By comparing Example 1 and Example 3, it can be seen that on the basis of 0.01≤d≤0.09, 0<f+h≤0.05, 0.005≤z≤0.035, when z1≥z / 4 and z≥d / 5 are further controlled, the kinetic degradation problem caused by the introduction of Zn can be improved. At the same time, in the first and second sintering stages, the surface ion channels can be optimized and a coating layer can be formed, thereby significantly improving the overall rate performance of the material.

[0258] Furthermore, by comparing Examples 8, 12, 14 and 15, it can be seen that when z1<z / 4 or z<d / 5, problems such as poor rate performance, poor cycle performance and excessive residual alkali of the material may occur.

[0259] Comparing Example 1 and Example 4, it can be seen that on the basis of 0.01≤d≤0.09, 0<f+h≤0.05, 0.005≤z≤0.035, when x≥1-d is further controlled, the material capacity can be improved and the residual alkali can be reduced.

[0260] By comparing Examples 2, 5, and 6, it can be seen that on the basis of 0.01≤d≤0.09, 0<f+h≤0.05, 0.005≤z≤0.035, (0.1-fh)≥d and h≥f, by further controlling z1≥z / 4 and z≥d / 5, the kinetic properties of the material can be improved, that is, by improving the intercalation and deintercalation ability of sodium ions, thereby optimizing the rate performance.

[0261] Comparing Examples 2, 7, 8 and 12, it can be seen that, on the basis of 0.01≤d≤0.09, 0<f+h≤0.05, 0.005≤z≤0.035, (0.1-fh)≥d and h≥f, further controlling x≥1-d is beneficial to improving the material capacity and reducing the residual alkali.

[0262] By comparing Examples 3, 10, 11 and 13, it can be seen that on the basis of 0.01≤d≤0.09, 0<f+h≤0.05, 0.005≤z≤0.035, z1≥z / 4 and z≥d / 5, further controlling x≥1-d can improve the material capacity, optimize the rate performance and cycle performance, and reduce the residual alkali of the material.

[0263] By comparing Examples 6-13 with Examples 14 and 15, it can be seen that on the basis of 0.01≤d≤0.09, 0<f+h≤0.05, 0.005≤z≤0.035, (0.1-fh)≥d and h≥f, z1≥z / 4 and z≥d / 5, further controlling x≥1-d can improve the sodium embedding ability of the material and the stability of the structure, thereby improving the capacity of the material, making the material cycle more stable, optimizing the residual alkali content, reducing the sensitivity to moisture, and improving the rate performance.

[0264] By comparing Examples 3, 10, 11 and 13, it can be seen that on the basis of 0.01≤d≤0.09, 0<f+h≤0.05, 0.005≤z≤0.035, z1≥z / 4 and z≥d / 5, when 0.8≤d / (f+h)≤1.2 and x satisfies 0.95≤x≤0.98, the capacity utilization, rate cycle, residual alkali and sensitivity to water of the material are further optimized.

[0265] By comparing Examples 14-16 with Examples 17-20, it can be seen that on the basis of 0.01≤d≤0.09, 0<f+h≤0.05, 0.005≤z≤0.035, (0.1-fh)≥d and h≥f, z1≥z / 4 and z≥d / 5, x≥1-d, when 0.8≤d / (f+h)≤1.2 and x satisfies 0.95≤x≤0.98, when Zn is introduced into the material, its advantages can be fully exerted and its disadvantages can be improved to the greatest extent.

[0266] In summary, it can be seen that the overall electrochemical performance of the material is: 0.2C discharge is 140-150mAh / g, 1C discharge is 136-140 mAh / g, and the performance difference in the capacity of the material is mainly reflected in the Zn content in the bulk phase. The greater the Zn content, the more capacity the material can release at its 2.0-4.0V, and the corresponding 3.8-4.0V phase change potential will be advanced in this range. At the same time, the cycle performance of the material will also decrease; from the content and proportion of Zn, Cu, and Mg in the embodiment, when the Zn content d is greater and the content of magnesium and Cu is smaller h+f, the phase change potential will be lower, the material capacity will be higher, but the cycle stability will be worse. On the contrary, the smaller the Zn content d and the larger the Mg and Cu content h+f, the higher the phase change potential will be, the material capacity will decrease, but the cycle stability will be better; but when Mg and Cu are in the range of (0.1-fh)<d and h≥f, the overall performance of the material is the best; in addition, for the limitations of Z and Co content, when they satisfy z1≥z / 4 and z≥d / 5, the rate performance of the material is better and the cycle stability of the material is higher, but when the Co content z1<z / 4, the rate performance of the material deteriorates and the cycle stability decreases.

[0267] The charge and discharge curves of the button battery prepared in Example 1 at 0.2C and 1.0C are plotted as follows: Figure 5 As shown, it can be seen that the material has a 0.2C discharge capacity of 145mAh / g and a 1C discharge capacity of 140mAh / g. It begins to phase change around 3.95V, has a high overall capacity, and has small polarization.

[0268] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the above-described embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the above-described embodiments within the technical scope disclosed by the present invention, or replace some of the technical features therein with equivalents. Such modifications, changes, or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A positive electrode active material, characterized in that The main phase is composed of O3-type layered oxides; The chemical formula of the layered oxide is Na x Ni a Fe b Mn c Zn d Cu f Mg h M z O2; Among them, a+b+c+d+f+h+z=1, 0.90≤x≤0.99, 0.20≤a≤0.25, 0.25≤b≤0.35, 0.25≤c≤0.45, 0.01≤d≤0.09, 0<f+h≤0.05, 0.005≤z≤0.035; M is composed of mandatory Co and optional doping metals, wherein the doping metal includes at least one of Ca, Ti, Zr, W, Ta, Mo, Sr and Nb.

2. The positive electrode active material according to claim 1, characterized in that The chemical formula of the layered oxide satisfies at least one of the following conditions: (1) d, f, and h satisfy the following ranges: (0.1-fh)≥d and h≥f; (2) The number of atoms of Co in M ​​is z1, and the number of atoms of other elements in M ​​is (z-z1); z1 satisfies the following range: z1 ≥ z / 4 and z ≥ d / 5; (3) x ≥ 1-d; (4) When 0.8≤d / (f+h)≤1.2, x satisfies 0.95≤x≤0.

98.

3. A method for preparing a positive electrode active material, characterized in that: uniformly mixing a portion of a sodium source, a nickel source, an iron source, a manganese source, a zinc source, a copper source, a magnesium source, and a cobalt source to obtain a sintered precursor; performing a primary sintering on the sintered precursor, and then mixing the primary sintered product with the remaining sodium source and an optional doped metal precursor and performing a secondary sintering to obtain a positive electrode active material; Among them, cobalt source and doping metal precursor are used as doping material M, sodium source, nickel source, iron source, manganese source, zinc source, copper source, magnesium source, doping material M is as follows: x Ni a Fe b Mn c Zn d Cu f Mg h M z The chemical formula of O2 is a+b+c+d+f+h+z=1, 0.90≤x≤0.99, 0.20≤a≤0.25, 0.25≤b≤0.35, 0.25≤c≤0.45, 0.01≤d≤0.09, 0<f+h≤0.05, 0.005≤z≤0.

035.

4. The preparation method according to claim 3, characterized in that The temperatures of the primary sintering and the secondary sintering are independently 800-950°C; And / or, the time of the primary sintering and the secondary sintering are each independently 12 to 24 hours; And / or, the atmosphere of the primary sintering and the secondary sintering is air and / or oxygen.

5. The preparation method according to claim 3, characterized in that The sodium source is selected from at least one of anhydrous sodium carbonate, sodium carbonate monohydrate, sodium carbonate decahydrate, sodium bicarbonate and sodium sulfate; And / or, the cobalt source is selected from at least one of a Co-containing oxide, a Co-containing sulfide and a Co-containing nitride; and / or, the doped metal precursor comprises at least one of an oxide containing a doped metal, a sulfide containing a doped metal, and a nitride containing a doped metal; And / or, the doped metal precursor is a nanomaterial.

6. A positive electrode plate, characterized in that: The positive electrode active material comprises the positive electrode active material according to claim 1 or 2, or comprises the positive electrode active material prepared by the preparation method according to any one of claims 3 to 5.

7. A sodium ion secondary battery, characterized in that: The positive electrode active material comprises the positive electrode active material according to claim 1 or 2, or comprises the positive electrode active material prepared by the preparation method according to any one of claims 3 to 5, or comprises the positive electrode sheet according to claim 6.

8. An electrical equipment, characterized in that: Including the sodium ion secondary battery according to claim 7.

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