High-nickel ternary positive electrode material, preparation method thereof and battery cell

Abstract

The application provides a high-nickel ternary positive electrode material, a preparation method thereof and a battery cell. The preparation method comprises the following steps: S1, mixing raw materials comprising a water-soluble A-element-containing compound, a nickel salt, a cobalt salt, a manganese salt and water to obtain a first mixed solution; S2, mixing a non-water-soluble M-element-containing compound and an organic solvent to obtain a second mixed solution; S3, co-precipitating raw materials comprising the first mixed solution and the second mixed solution under an alkaline condition to obtain a high-nickel ternary precursor; and S4, performing first sintering on raw materials comprising a lithium salt and the high-nickel ternary precursor to obtain the high-nickel ternary positive electrode material. By introducing two doping elements A and M respectively in the precursor preparation process through a liquid phase method, the microstructure of the high-nickel ternary positive electrode material is improved, and the structural stability and the cycle performance of the high-nickel ternary positive electrode material under high voltage are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a high-nickel ternary positive electrode material, a preparation method thereof and a battery cell. BACKGROUND

[0002] Ternary lithium-ion power batteries have the advantages of high energy density and long cruising range, and in recent years, the installed capacity of power batteries accounts for about 40%. In view of the current high-nickel ternary precursor and finished ternary material Li(Ni x Co y Mn 1-x-y )O2(x≥0.8) is expensive, i.e., the cost of the battery using the positive electrode material is high, the development of low-cost high-nickel ternary positive electrode material and battery cell design has the advantages of cost reduction and efficiency improvement.

[0003] High nickel and high voltage are important branches in the current development route of ternary positive electrode materials. Both can increase the theoretical and actual gram capacity of the material. High nickel has been developed to 8 and 9 series products, and the material has already reached mass production capacity. High voltage is mostly applied to medium nickel (Ni<70mol%) products, and its voltage can be increased to 4.6V and above. How to effectively combine high nickel and high voltage in two directions while ensuring high capacity and long cycle life of the material is an important improvement direction for high-nickel ternary positive electrode materials.

[0004] A high-nickel ternary single crystal material precursor is prepared by an alkaline composite dispersion liquid assisted co-precipitation method, which is disclosed in a Chinese patent application with the patent authorization publication number CN114436346A. The process is simpler, the particle size is controllable and has a narrow distribution, the morphology is uniform, the dispersion is high, the product consistency is good, and large-scale production can be realized. A high-nickel ternary single crystal material is prepared by controlling the synthesis process of the material precursor, crushing and grading the precursor, mixing the precursor with a lithium source, obtaining a pre-oxide by low-temperature dehydration, and then high-temperature sintering in a dynamic rotary furnace, which is disclosed in a Chinese patent with the patent authorization publication number CN112531158B. The high-nickel ternary single crystal material prepared by this method has the characteristics of full primary particle morphology, uniform dispersion, complete crystal form, stable structure, excellent electrochemical energy, etc. A method for preparing a high-voltage ternary positive electrode material by mixing and calcining Al and Ni additives, and application thereof, are disclosed in a Chinese patent application with the patent authorization publication number CN117691101A, which has the advantages of high cycle stability and high specific capacity. However, the ternary positive electrode materials obtained by the above preparation methods are difficult to simultaneously consider high voltage, high capacity and long cycle life. SUMMARY

[0005] The main objective of this invention is to provide a high-nickel ternary cathode material, its preparation method, and a battery cell, so as to solve the problem that ternary cathode materials in the prior art cannot simultaneously achieve high voltage, high capacity, and long cycle life.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for preparing a high-nickel ternary cathode material is provided. The method includes: step S1, mixing raw materials comprising a water-soluble compound containing element A, a nickel salt, a cobalt salt, a manganese salt, and water to obtain a first mixed solution; step S2, mixing a non-water-soluble compound containing element M with an organic solvent to obtain a second mixed solution; step S3, under alkaline conditions, co-precipitating the raw materials comprising the first and second mixed solutions to obtain a high-nickel ternary precursor; and step S4, performing a first sintering of the raw materials comprising a lithium salt and the high-nickel ternary precursor to obtain the high-nickel ternary cathode material; wherein the general chemical formula of the high-nickel ternary precursor is Ni. x Co y Mn z A m M n (OH)₂, where A and M are each independently selected as doping elements, and A and M are each independently selected from any one or more of Ti, Nb, Zr, Te, W, and Mo, x + y + z ≥ 0.99, 0.8 ≤ x < 1, 0 <y<0.2,m+n≤0.01,m<0.01,n<0.01。

[0007] Furthermore, the D of the above-mentioned high-nickel ternary precursor 50 The particle size is 3–5 μm, and / or m < 0.005, n < 0.005, and / or m:n = 0.1–10:1.

[0008] Furthermore, the total concentration of metal ions in the first mixed solution is 1.5–3 mol / L, and / or the total concentration of A ions in the first mixed solution is 1.5–30 mmol / L.

[0009] Furthermore, the total concentration of M ions in the second mixed solution is 0.015–0.3 mol / L; and / or the organic solvent is ethanol or an ethanol solution containing dissolved sodium hydroxide, wherein the pH value of the ethanol solution containing dissolved sodium hydroxide is 11–13.

[0010] Furthermore, the volume ratio of the first mixed solution to the second mixed solution is 1:0.005 to 1.

[0011] Furthermore, the pH value of the coprecipitation is 11-12, controlled by ammonia and NaOH solution; and / or the coprecipitation temperature is 50-60℃; and / or stirring is carried out during the coprecipitation process at a speed of 400-600 rpm.

[0012] Furthermore, the temperature of the first sintering is 850℃~950℃, the heating rate of the first sintering is 1~5℃ / min, and the time of the first sintering is 3~10h.

[0013] Furthermore, the above preparation method also includes: subjecting the raw materials, including the product obtained after the first sintering and the coating agent, to a second sintering to obtain a high-nickel ternary cathode material; wherein the molar ratio of the product obtained after the first sintering to the coating agent is 1:0.0001 to 0.001; and / or the coating agent is selected from any one or more of Al2O3, BaO, MgCO3, V2O5, and B2O3; and / or the temperature of the second sintering is 500℃ to 800℃, the heating rate of the second sintering is 1 to 5℃ / min, and the time of the second sintering is 3 to 10h.

[0014] According to another aspect of the present invention, a high-nickel ternary cathode material is provided, which is prepared by the above-described preparation method.

[0015] According to another aspect of the present invention, a battery cell is provided, comprising a positive electrode and a negative electrode, wherein the positive electrode comprises a positive electrode active material, the negative electrode comprises a negative electrode active material, the negative electrode active material is silicon-oxygen graphite, and the positive electrode active material is the aforementioned high-nickel ternary positive electrode material, wherein the operating voltage range of the battery cell is 2.75 to 4.35V.

[0016] By applying the technical solution of this invention, this application introduces two doping elements, A and M, during the precursor preparation process using a liquid-phase method. The introduced A and M doping elements exist in the layered structure as high-strength AO and MO bonds, respectively, improving the microstructure of the high-nickel ternary cathode material and enhancing its structural stability and cycle performance under high voltage (total voltage ≥ 4.3V). Simultaneously, combining high nickel content and high voltage further enhances the reversible discharge specific capacity of the high-nickel ternary cathode material. While meeting the charge-discharge cycle life requirements, this approach helps reduce the amount of cathode material used, thereby reducing cell costs. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0018] Figure 1 The following graphs show the capacity retention rates of Embodiment 1, Comparative Example 1, and Comparative Example 2 at room temperature 1C / 1C.

[0019] Figure 2SEM images of the high-nickel ternary cathode material in Embodiment 1 of this application are shown;

[0020] Figure 3 SEM images of the high-nickel ternary cathode material in Comparative Example 1 of this application are shown;

[0021] Figure 4 SEM images of the high-nickel ternary cathode material in Comparative Example 2 of this application are shown;

[0022] Figure 5 The XRD patterns of the high-nickel ternary cathode materials in Embodiment 1, Comparative Example 1, and Comparative Example 2 of this application are shown. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] As analyzed in the background section of this application, the existing technology has the problem that ternary cathode materials cannot simultaneously achieve high voltage, high capacity and long cycle life. This application provides a high-nickel ternary cathode material, its preparation method and battery cell.

[0025] In a typical embodiment of this application, a method for preparing a high-nickel ternary cathode material is provided. The method includes: step S1, mixing raw materials comprising a water-soluble compound containing element A, nickel salt, cobalt salt, manganese salt, and water to obtain a first mixed solution; step S2, mixing a non-water-soluble compound containing element M with an organic solvent to obtain a second mixed solution; step S3, under alkaline conditions, co-precipitating the raw materials comprising the first and second mixed solutions to obtain a high-nickel ternary precursor; and step S4, performing a first sintering of the raw materials comprising lithium salt and the high-nickel ternary precursor to obtain the high-nickel ternary cathode material; wherein the general chemical formula of the high-nickel ternary precursor is Ni. x Co y Mn z A m M n (OH)₂, where A and M are each independently selected as doping elements, and A and M are each independently selected from any one or more of Ti, Nb, Zr, Te, W, and Mo, x + y + z ≥ 0.99, 0.8 ≤ x < 1, 0 <y<0.2,m+n≤0.01,m<0.01,n<0.01。

[0026] This application introduces two doping elements, A and M, during the precursor preparation process using a liquid-phase method. The introduced A and M doping elements exist in the layered structure as high-strength AO and MO bonds, improving the microstructure of the high-nickel ternary cathode material and enhancing its structural stability and cycle performance under high voltage (total voltage ≥ 4.3V). Simultaneously, combining high nickel content and high voltage further enhances the reversible discharge specific capacity of the high-nickel ternary cathode material. While meeting charge-discharge cycle life requirements, this approach helps reduce the amount of cathode material used, thereby lowering cell costs.

[0027] In one embodiment of this application, the D of the above-mentioned high-nickel ternary precursor 50 The particle size is 3–5 μm, and / or m < 0.005, n < 0.005, and / or m:n = 0.1–10:1.

[0028] Preferred control of D in high-nickel ternary precursors 50 Particle size within the aforementioned range is beneficial for improving the consistency and uniform dispersion of high-nickel ternary cathode materials, thereby increasing their compaction density and electrochemical performance. Controlling the doping concentration and the proportion of doping elements within the aforementioned range is beneficial for effectively and uniformly improving the stability of the layered structure under high nickel concentration conditions, reducing performance degradation caused by excessive doping, and thus helping to maintain good electrochemical activity and cycle stability under high voltage conditions.

[0029] In one embodiment of this application, the total concentration of metal ions in the first mixed solution is 1.5 to 3 mol / L, and / or the total concentration of A ions in the first mixed solution is 1.5 to 30 mmol / L.

[0030] Preferably controlling the total concentration of metal ions in the first mixed solution within the aforementioned range is beneficial for forming a denser particle structure, thereby improving the compaction performance of the high-nickel ternary cathode material and increasing the energy density of the battery. Controlling the total concentration of A ions within the aforementioned range also helps to increase their content and uniform dispersion in the high-nickel ternary cathode material, enhancing its microstructure and thus contributing to improved structural stability and electrochemical performance, ultimately increasing the battery's cycle life and capacity.

[0031] In one embodiment of this application, the total concentration of M ions in the second mixed solution is 0.015 to 0.3 mol / L; and / or the organic solvent is ethanol or an ethanol solution containing dissolved sodium hydroxide, wherein the pH value of the ethanol solution containing dissolved sodium hydroxide is 11 to 13.

[0032] Precisely controlling the range of the above conditions is beneficial for more uniformly co-precipitating with metal ions in the first mixed solution during the co-precipitation process, forming a high-nickel ternary precursor with higher structural stability. This is beneficial for enhancing the structural stability and electrochemical performance of the high-nickel ternary cathode material under high voltage, and improving the cycle life and capacity of the battery.

[0033] In one embodiment of this application, the volume ratio of the first mixed solution to the second mixed solution is 1:0.005 to 1.

[0034] Preferentially controlling the range of the above conditions helps to control the doping amount of A and M elements in high-nickel ternary cathode materials and improves the uniform dispersion of dopants in high-nickel ternary cathode materials.

[0035] In one embodiment of this application, the pH value of the coprecipitation is 11-12, and the pH value of the coprecipitation is controlled by ammonia water and NaOH solution; and / or the temperature of the coprecipitation is 50-60°C; and / or stirring is carried out during the coprecipitation process, and the stirring speed is 400-600 rpm.

[0036] Precisely controlling the coprecipitation conditions within the above range is beneficial to improving the efficiency and effectiveness of coprecipitation.

[0037] In one embodiment of this application, the temperature of the first sintering is 850℃~950℃, the heating rate of the first sintering is 1~5℃ / min, and the time of the first sintering is 3~10h.

[0038] Preferably controlling the sintering conditions of the first sintering within the above range is beneficial to forming a complete crystal structure and improving the structural stability of the high-nickel ternary cathode material.

[0039] In one embodiment of this application, the above preparation method further includes: subjecting the raw materials, including the product obtained after the first sintering and the coating agent, to a second sintering to obtain a high-nickel ternary cathode material; wherein the molar ratio of the product obtained after the first sintering to the coating agent is 1:0.0001 to 0.001; and / or the coating agent is selected from any one or more of Al2O3, BaO, MgCO3, V2O5, and B2O3; and / or the temperature of the second sintering is 500℃ to 800℃, the heating rate of the second sintering is 1 to 5℃ / min, and the time of the second sintering is 3 to 10h.

[0040] By controlling the type of coating agent and the conditions of secondary sintering within the above range, it is beneficial to coat the surface of the high-nickel ternary cathode material with a dense coating layer, thereby further improving the cycle stability of the high-nickel ternary cathode material under high voltage, reducing capacity decay during cycling, and increasing the electronic conductivity of the high-nickel ternary cathode material, thus improving the overall performance of the battery.

[0041] In another typical embodiment of this application, a high-nickel ternary cathode material is provided, which is prepared by the above-described preparation method.

[0042] The high-nickel ternary cathode material prepared by the above method has better cycle stability and electrochemical performance, which is beneficial to improving battery capacity and cycle life, and reducing the cost of cathode material.

[0043] In another typical embodiment of this application, a battery cell is provided, including a positive electrode and a negative electrode. The positive electrode includes a positive electrode active material, and the negative electrode includes a negative electrode active material. The negative electrode active material is silicon-oxygen graphite, and the positive electrode active material is the aforementioned high-nickel ternary positive electrode material. The operating voltage range of the battery cell is 2.75 to 4.35V.

[0044] The battery cell in this application, by employing a combination of high-nickel ternary cathode material and silicon-oxygen-graphite anode, and by optimizing the cell's operating voltage range, effectively meets the performance requirements of both high nickel content and high voltage. This allows the cell to exhibit higher energy density and longer cycle life at high voltages, reducing costs and improving overall battery performance, thereby meeting the demands of new energy vehicles and energy storage systems for high-energy-density and long-life batteries. Furthermore, the battery cell can be any of the following: pouch, prismatic, or cylindrical.

[0045] The following parameters are optimized during the fabrication process of the battery cell in this application:

[0046] During the cell manufacturing process, the mass ratio of positive electrode active material: conductive agent: binder is 95-98:1-3:1-2;

[0047] During the cell manufacturing process, the mass ratio of negative electrode active material: conductive agent: binder is 95-96:1-2:1-3;

[0048] The positive electrode surface density is designed to be 340–360 g / m³ during the cell manufacturing process. 2 ;

[0049] The negative electrode surface density is designed to be 200–210 g / m³ during the cell manufacturing process. 2 ;

[0050] The compaction density of the positive electrode sheet during the cell manufacturing process is designed to be 3.4–3.5 g / m³. 3 ;

[0051] The compaction density of the negative electrode sheet during the battery cell manufacturing process is designed to be 1.6–1.7 g / m³. 3 ;

[0052] During the cell fabrication process, the separator is set to a conventional ceramic separator, specifically including a base film and alumina ceramic layers coated on both sides of the base film; wherein, the base film uses a polyolefin material with a thickness of 9μm, and the thickness of each single alumina ceramic layer is 1.5μm;

[0053] During the cell manufacturing process, the electrolyte is set as a fluorocarbonate electrolyte, wherein the organic solvent is a mixed solvent of ethylene carbonate and diethyl carbonate with a mass ratio of 1:2 to 3, the lithium salt is 1M LiPF6, and the additive is a mixed additive of fluoroethylene carbonate and vinylene carbonate, which account for 2 to 5% and 0.5 to 2% of the total mass of the electrolyte (obtained by mixing organic solvent, lithium salt and additive), respectively.

[0054] The electrolyte injection coefficient is set to 2-4 g / Ah during the battery cell manufacturing process;

[0055] During the cell manufacturing process, the ratio of negative electrode capacity to positive electrode capacity is set to 1.05–1.15:1 (N / P ratio).

[0056] The beneficial effects of this application will be further illustrated below with reference to the embodiments.

[0057] Example 1

[0058] According to the precursor Ni 0.896 Co 0.049 Mn 0.049 Nb 0.003 Ti 0.003 The stoichiometric ratio of (OH)2 is obtained by dissolving nickel sulfate, cobalt sulfate, manganese sulfate and water-soluble niobium oxalate in a certain amount of deionized water to obtain mixed solution I, wherein the total concentration of metal ions in mixed solution I is 2 mol / L, and the total concentration of niobium ions in mixed solution I is 6 mmol / L. The time for pumping mixed solution I into the reaction vessel is 2.5 h, and the rate is 160 L / h.

[0059] According to the precursor Ni 0.896 Co 0.049 Mn 0.049 Nb 0.003 Ti 0.003 The stoichiometric ratio of (OH)2 is used to dissolve titanium ethoxide (ethyl titanate) in a certain amount of ethanol to obtain mixed solution II, and the total concentration of titanium ions in mixed solution II is 0.05 mol / L. Mixed solution II is pumped into the reaction vessel for 1 hour at a rate of 48 L / h.

[0060] Mixed solution I, mixed solution II, ammonia solution, and NaOH solution were fed into a reaction vessel, with the volume ratio of mixed solution I to mixed solution II being 1:0.12. The amounts of ammonia solution and NaOH solution added were adjusted to bring the pH of the solution in the reaction vessel to 11.6. A co-precipitation reaction occurred when the solution temperature was 60°C and the stirring speed was 500 rpm. After the reaction was completed, the solution was centrifuged, dried, and sieved to obtain D. 50 Ni high-nickel ternary precursor with a particle size of 3μm 0.896 Co 0.049 Mn 0.049 Nb 0.003 Ti 0.003 (OH)2.

[0061] Under an oxygen atmosphere, the D prepared above was... 50 Ni high-nickel ternary precursor with a particle size of 3μm 0.896 Co 0.049 Mn 0.049 Nb 0.003 Ti 0.003 (OH)₂ and lithium salt (LiOH·H₂O) were mixed uniformly at a molar ratio of 1:1.04. The mixture was heated to 925℃ at a rate of 2℃ / min and then subjected to a first sintering. After 6 hours of the first sintering, a high-nickel ternary material core was obtained. Then, the high-nickel ternary material core was mixed uniformly with B₂O₃ at a molar ratio of 1:0.0003. The mixture was then heated to 650℃ at a rate of 2℃ / min and then subjected to a second sintering. After 4 hours of the first sintering, a high-nickel ternary cathode material was obtained.

[0062] A 1.7Ah pouch cell was fabricated by combining high-nickel ternary cathode material as the positive electrode active material with silicon-oxygen graphite as the negative electrode active material. The following parameters were optimized during the cell fabrication process:

[0063] In the battery cell manufacturing process, the mass ratio of positive electrode active material: conductive agent: binder is 97.8:1.2:1.0;

[0064] During the battery cell manufacturing process, the mass ratio of negative electrode active material: conductive agent: binder is 95:2:3.

[0065] The positive electrode surface density was designed to be 350 g / m² during the cell manufacturing process. 2 ;

[0066] The negative electrode surface density was designed to be 206 g / m³ during the cell manufacturing process. 2 ;

[0067] The compaction density of the positive electrode sheet during the cell manufacturing process is designed to be 3.45 g / m³. 3 ;

[0068] The compaction density of the negative electrode sheet during the cell manufacturing process is designed to be 1.65 g / m³. 3 ;

[0069] During the cell fabrication process, the separator is set to a conventional ceramic separator, specifically including a base film and alumina ceramic layers coated on both sides of the base film; wherein, the base film uses a polyolefin material with a thickness of 9μm, and the thickness of each single alumina ceramic layer is 1.5μm;

[0070] During the cell manufacturing process, the electrolyte is set as a fluorocarbonate electrolyte, wherein the organic solvent is a mixed solvent of ethylene carbonate and diethyl carbonate with a mass ratio of 3:7, the lithium salt is 1M LiPF6, and the additive is a mixed additive of fluoroethylene carbonate and vinylene carbonate, which account for 3% and 1% of the total mass of the electrolyte (obtained by mixing organic solvent, lithium salt and additive), respectively.

[0071] The electrolyte injection coefficient was set at 2.8 g / Ah during the cell manufacturing process;

[0072] During the cell manufacturing process, the ratio of negative electrode capacity to positive electrode capacity is set to 1.08:1 (N / P ratio).

[0073] Example 2

[0074] The difference from Example 1 is that, according to the precursor Ni 0.896 Co 0.049 Mn 0.049 Nb 0.003 Ti 0.003 The stoichiometric ratio of (OH)2 was used to dissolve titanium ethoxide (ethyl titanate) in a certain amount of ethanol containing sodium hydroxide (the pH of the sodium hydroxide-ethanol solution was 12) to obtain mixed solution II (the concentration of titanium ions in mixed solution II, the volume ratio of mixed solution I to mixed solution II, the pumping time and speed were all consistent with those in Example 1), and finally a 1.7Ah soft-pack battery cell was produced.

[0075] Example 3

[0076] The difference from Example 1 is that the total concentration of metal ions in mixed solution I is 1.5 mol / L, the total concentration of niobium ions in mixed solution I is 1.5 mmol / L, the total concentration of titanium ions in mixed solution II is 0.015 mol / L, the volume ratio of mixed solution I to mixed solution II is 1:1, the pumping rate of mixed solution I and mixed solution II is 50 L / h, and the time is 2h (all other parameters are consistent with Example 1), and finally a 1.7Ah soft-pack battery cell is produced.

[0077] Example 4

[0078] The difference from Example 1 is that the total concentration of metal ions in mixed solution I is 3 mol / L, the total concentration of niobium ions in mixed solution I is 30 mmol / L, the total concentration of titanium ions in mixed solution II is 0.3 mol / L, the volume ratio of mixed solution I to mixed solution II is 1:0.01, the pumping rates of mixed solution I and mixed solution II are 200 L / h and 5 L / h, respectively, and the times are 2.5 h and 1 h, respectively (all other parameters are consistent with Example 1), and finally a 1.7 Ah soft-pack battery cell is produced.

[0079] Example 5

[0080] The difference from Example 1 is that the total concentration of metal ions in mixed solution I is 5 mol / L, the total concentration of niobium ions in mixed solution I is 50 mol / L, and the total concentration of titanium ions in mixed solution II is 0.5 mol / L (all other parameters are consistent with Example 1), and a 1.7Ah soft-pack battery cell is finally produced.

[0081] Example 6

[0082] The difference from Example 1 is that the total concentration of metal ions in mixed solution I is 1.5 mol / L, the total concentration of niobium ions in mixed solution I is 15 mmol / L, the total concentration of titanium ions in mixed solution II is 0.3 mol / L, the volume ratio of mixed solution I to mixed solution II is 1:0.005, the pumping rates of mixed solution I and mixed solution II are 200 L / h and 5 L / h, respectively, and the pumping times are 5 h and 1 h, respectively (all other parameters are consistent with Example 1). Finally, a 1.7 Ah soft-pack battery cell was produced.

[0083] Example 7

[0084] The difference from Example 1 is that the total concentration of titanium ions in mixed solution II is 0.005 mol / L, the volume ratio of mixed solution I to mixed solution II is 1:1.2, the pumping rate of mixed solution I and mixed solution II is 60 L / h and 50 L / h respectively, and the time is 2 h for both (all other parameters are the same as in Example 1), and finally a 1.7 Ah soft-pack battery cell is produced.

[0085] Example 8

[0086] The difference from Example 1 is that the amount of ammonia solution and NaOH solution added was adjusted to make the pH value of the solution in the reactor 11, and finally a 1.7Ah soft-pack battery cell was produced.

[0087] Example 9

[0088] The difference from Example 1 is that the amount of ammonia solution and NaOH solution added was adjusted to make the pH value of the solution in the reactor 12, and finally a 1.7Ah soft-pack battery cell was produced.

[0089] Example 10

[0090] The difference from Example 1 is that the amount of ammonia solution and NaOH solution added was adjusted to make the pH value of the solution in the reactor 13, and finally a 1.7Ah soft-pack battery cell was produced.

[0091] Example 11

[0092] The difference from Example 1 is that the first sintering temperature is 850°C, and a 1.7Ah soft-pack battery cell is finally produced.

[0093] Example 12

[0094] The difference from Example 1 is that the first sintering temperature is 950°C, and a 1.7Ah soft-pack battery cell is finally produced.

[0095] Example 13

[0096] The difference from Example 1 is that the first sintering temperature is 1000°C, and a 1.7Ah soft-pack battery cell is finally produced.

[0097] Example 14

[0098] The difference from Example 1 is that the molar ratio of the high-nickel ternary material core to B2O3 is 1:0.0001, which ultimately produces a 1.7Ah soft-pack battery cell.

[0099] Example 15

[0100] The difference from Example 1 is that the molar ratio of the high-nickel ternary material core to B2O3 is 1:0.001, which ultimately produces a 1.7Ah soft-pack battery cell.

[0101] Example 16

[0102] The difference from Example 1 is that the molar ratio of the high-nickel ternary material core to B2O3 is 1:0.002, which ultimately produces a 1.7Ah soft-pack battery cell.

[0103] Example 17

[0104] The difference from Example 1 is that the high-nickel ternary material core is not coated with B2O3, and the high-nickel ternary cathode material is directly used as the high-nickel ternary cathode material, and finally a 1.7Ah soft-pack battery cell is made.

[0105] Comparative Example 1

[0106] According to the precursor Ni 0.90 Co 0.05 Mn 0.05The stoichiometric ratio of (OH)₂ was determined by dissolving nickel sulfate, cobalt sulfate, and manganese sulfate in a certain amount of deionized water to obtain a mixed solution with a total metal ion concentration of 2 mol / L. The mixed solution, ammonia solution, and NaOH solution were then introduced into a reaction vessel, and the amounts of ammonia solution and NaOH solution added were adjusted to maintain a pH of 11.6. A co-precipitation reaction occurred at a solution temperature of 60℃ and a stirring speed of 500 rpm. After the reaction was completed, the solution was centrifuged, dried, and sieved to obtain D. 50 Ni high-nickel ternary precursor with a particle size of 3μm 0.90 Co 0.05 Mn 0.05 (OH)2.

[0107] Under an oxygen atmosphere, the D prepared above was... 50 Ni high-nickel ternary precursor with a particle size of 3μm 0.90 Co 0.05 Mn 0.05 (OH)2, lithium salt (LiOH·H2O), Nb2O5 and TiO2 were mixed uniformly, with a molar ratio of precursor to lithium salt of 1:1.04. The mixture was heated to 925℃ at a heating rate of 2℃ / min and then subjected to a first sintering. After 6 hours of the first sintering, a high-nickel ternary material core was obtained. Then, the high-nickel ternary material core was mixed uniformly with B2O3, with a molar ratio of high-nickel ternary material core to B2O3 of 1:0.0003. The mixture was heated to 650℃ at a heating rate of 2℃ / min and then subjected to a second sintering. After 4 hours of the first sintering, a high-nickel ternary cathode material was obtained.

[0108] By combining high-nickel ternary cathode material as the positive electrode active material with silicon-oxygen graphite as the negative electrode active material, a 1.7Ah soft-pack battery cell was finally manufactured.

[0109] Comparative Example 2

[0110] The difference from Example 1 is that niobium oxalate and titanium ethoxide (tetraethyl titanate) are dissolved together in deionized water to obtain a mixed solution. The concentration of niobium ions in the mixed solution is the same as the total concentration of niobium ions in the mixed solution I of Example 1, and the amount of titanium ions added in the mixed solution is the same as the amount of titanium ions introduced in Example 1. Finally, a 1.7Ah soft-pack battery cell is produced.

[0111] Performance testing:

[0112] The soft-pack cells of the above embodiments and comparative examples were tested. Specifically, the working voltage range was set to 2.75 to 4.35V, and the reversible specific capacity of the positive electrode at 0.33C and the capacity retention rate after 1200 cycles at room temperature 1C / 1C were measured. Table 1 shows the test results. The chemical formulas of the high-nickel ternary positive electrode materials obtained from the embodiments and comparative examples are also listed in Table 1.

[0113] Table 1

[0114]

[0115]

[0116] The ICP results of the high-nickel ternary cathode materials of Examples 1, Comparative Examples 1 and 2 are shown in Table 2.

[0117] Table 2

[0118] Examples / Comparative Examples Ni (mol%) Co (mol%) Mn (mol%) Nb (ppm) Ti (ppm) Example 1 89.59 4.89 4.89 2931 3047 Comparative Example 1 89.57 4.89 4.90 3026 3010 Comparative Example 2 89.62 4.97 4.98 3182 986

[0119] Table 3 shows the XRD refined cell parameters of the high-nickel ternary cathode materials in Examples 1, 1, and 2. Here, 'a' represents the length of the cell along the a-axis (a single direction in the plane); 'c' represents the length of the cell along the c-axis (vertical direction, perpendicular to the plane containing the a-axis); 'c / a' refers to the ratio of 'c' to 'a', representing the growth priority of the cell along a certain direction; 'V' refers to the volume of the cell; and 'I' refers to the volume of the cell. 003 / I 104 The ratio of the two main diffraction intensity peaks in a material is used to evaluate the layered structure characteristics of the material.

[0120] Table 3

[0121] Examples / Comparative Examples a c c / a V I 003 / I 104 <!-- 9 -->]]> Example 1 2.86416 14.27932 4.98552 101.45 3.0116 Comparative Example 1 2.87712 14.19749 4.93462 101.78 1.6083 Comparative Example 2 2.86673 14.26618 4.97646 101.53 2.5302

[0122] The capacity retention curves of Embodiment 1, Comparative Example 1, and Comparative Example 2 of this application at room temperature 1C / 1C are shown in the figure below. Figure 1 As shown. From the appendix Figure 1 It can be seen that the capacity retention rate at room temperature 1C / 1C cycling is as follows: Example 1 retains 81.95% of the capacity after 1200 cycles, while Comparative Examples 1 and 2 retain 73.79% and 74.61% respectively. Therefore, Example 1 has a capacity retention rate advantage of >3%. The reason for this is that Example 1 introduces the dopant metal through a stepwise solvent method, resulting in a more uniform metal distribution in the precursor bulk phase and a higher degree of AO and MO bond bonding. In Comparative Example 1, the metal element introduced through solid-state sintering is mostly located on the surface of the precursor particles and does not enter the bulk structure excessively, leading to a decrease in the degree of AO and MO bond bonding. Comparative Example 2 uses a one-step solvent method to introduce the dopant; the water-soluble element A can be introduced by reacting the main element Ni / Co / Mn ions with OH groups. - During the bonding process, the dopant is evenly dispersed into the layered structure, while the non-water-soluble M element dopant cannot be evenly dispersed, resulting in a reduction in the amount of dopant entering the crystal structure (bulk phase and surface) compared to the design value.

[0123] The SEM images of the high-nickel ternary cathode materials in Examples 1, 1, and 2 of this application are shown in the following figures, respectively.Figure 2 , Figure 3 and Figure 4 The surface morphology results show that Example 1 and Comparative Example 2, due to the use of the co-precipitation solvent method to introduce dopant elements, have fewer dot-like coating marks on their surfaces and smoother particles. Comparative Example 1, however, uses a solid-state sintering method for doping, resulting in more dot-like coating marks on its surface. Combined with the data in Table 2, it can be seen that the measured contents of dopant elements A and M in Example 1 are very close to the design values, thanks to the good dispersion of both elements during the co-precipitation process. Comparative Example 1, using a solid-state sintering method to introduce dopant elements A and M, concentrates more on the surface, and the subsequent processing does not separate them from the material system, resulting in measured A and M contents close to the design values. In Comparative Example 2, because the dopant element M is not water-soluble, it did not fully enter the co-precipitation product, and its content in the precursor and ternary finished material is far lower than the design value.

[0124] The XRD patterns of the high-nickel ternary cathode materials in Embodiment 1, Comparative Example 1, and Comparative Example 2 of this application are as follows: Figure 5 As shown, where, Figure 5 In this context, 2θ represents the angle between the incident X-ray and the diffraction detector.

[0125] Examples 1, 1 (Comparative Example), and 2 (Comparative Example) all belong to the α-NaFeO2 hexagonal structure, with a significant main peak (003) signal intensity, corresponding to a typical layered structure. Combined with the data in Table 3, the XRD refinement results show that the c-axis of the material cell obtained in Example 1 increases, corresponding to an increase in the c / a value, i.e., an increase in the interlayer spacing. 003 / I 104 The increase indicates that it, to some extent, allows the unit cell to preferentially grow along the c-axis. This is because metal elements A and M enter the bulk structure, and their atomic radii are larger and their bonding ability with O is stronger. In Comparative Example 2, element A also successfully entered the bulk structure through a liquid-phase co-precipitation process, while element M was not successfully introduced due to differences in solubility. Its c-axis, c / a value, and I... 003 / I 104 Compared to Example 1, the size is reduced, while in Comparative Example 1, due to the solid-state sintering method, the doped elements are concentrated on the particle surface, having little impact on the unit cell parameters in the bulk phase. Its c-axis, c / a value, and I... 003 / I 104 Minimum, meaning the minimum interlayer spacing.

[0126] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0127] This application introduces two doping elements, A and M, during the precursor preparation process using a stepwise liquid-phase method. The introduced A and M doping elements exist in the layered structure as high-strength AO and MO bonds, improving the microstructure of the high-nickel ternary cathode material and enhancing its structural stability and cycle performance under high voltage (≥4.3V). Simultaneously, combining high nickel content and high voltage further improves the reversible discharge specific capacity of the high-nickel ternary cathode material. While meeting charge-discharge cycle life requirements, this approach helps reduce the amount of cathode material used, thereby lowering cell costs.

[0128] The above are merely embodiments of the present invention and are not intended to limit the invention. Those skilled in the art will recognize that the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a high-nickel ternary cathode material, characterized in that, The preparation method includes: Step S1 involves mixing raw materials including a water-soluble compound containing element A, nickel salt, cobalt salt, manganese salt, and water to obtain a first mixed solution. Step S2 involves mixing a non-water-soluble compound containing element M with an organic solvent to obtain a second mixed solution. Step S3: Under alkaline conditions, the raw materials including the first mixed solution and the second mixed solution are co-precipitated to obtain a high-nickel ternary precursor; Step S4: The raw materials including lithium salt and the high-nickel ternary precursor are subjected to a first sintering to obtain a high-nickel ternary cathode material; The general chemical formula of the high-nickel ternary precursor is Ni. x Co y Mn z A m M n (OH)₂, where A and M are each independently selected as doping elements, and A and M are each independently selected from any one or more of Ti, Nb, Zr, Te, W, and Mo, where x + y + z ≥ 0.99, 0.8 ≤ x < 1, and 0 <y<0.2,m+n≤0.01,m<0.01,n<0.01。 2. The preparation method according to claim 1, characterized in that, The high-nickel ternary precursor D 50 The particle size is 3~5μm, and / or m<0.005, n<0.005, and / or m:n=0.1~10:

1.

3. The preparation method according to claim 1 or 2, characterized in that, The total concentration of metal ions in the first mixed solution is 1.5~3 mol / L, and / or the total concentration of A ions in the first mixed solution is 1.5~30 mmol / L.

4. The preparation method according to claim 1 or 2, characterized in that, The total concentration of M ions in the second mixed solution is 0.015~0.3 mol / L; and / or the organic solvent is ethanol or an ethanol solution containing dissolved sodium hydroxide, wherein the pH value of the ethanol solution containing dissolved sodium hydroxide is 11~13.

5. The preparation method according to claim 1 or 2, characterized in that, The volume ratio of the first mixed solution to the second mixed solution is 1:0.005~1.

6. The preparation method according to claim 1 or 2, characterized in that, The pH value of the coprecipitation is 11-12, controlled by ammonia and NaOH solution; and / or the temperature of the coprecipitation is 50-60℃; and / or stirring is carried out during the coprecipitation process at a speed of 400-600 rpm.

7. The preparation method according to claim 1 or 2, characterized in that, The first sintering temperature is 850℃~950℃, the first sintering heating rate is 1~5℃ / min, and the first sintering time is 3~10h.

8. The preparation method according to claim 1 or 2, characterized in that, The preparation method further includes: The raw materials, including the product obtained after the first sintering and the coating agent, are subjected to a second sintering to obtain the high-nickel ternary cathode material; Wherein, the molar ratio of the product obtained after the first sintering to the coating agent is 1:0.0001~0.001; and / or the coating agent is selected from any one or more of Al2O3, BaO, MgCO3, V2O5 and B2O3; And / or the second sintering temperature is 500℃~800℃, the second sintering heating rate is 1~5℃ / min, and the second sintering time is 3~10h.

9. A high-nickel ternary cathode material, characterized in that, The high-nickel ternary cathode material is prepared by the preparation method described in any one of claims 1 to 8.

10. A battery cell comprising a positive electrode and a negative electrode, wherein the positive electrode comprises a positive electrode active material, and the negative electrode comprises a negative electrode active material, wherein the negative electrode active material is silicon-oxygen graphite, characterized in that, The positive electrode active material is the high-nickel ternary positive electrode material according to claim 9, wherein the working voltage range of the battery cell is 2.75~4.35V.

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