Iridium and praseodymium doped ternary precursor, positive electrode material, preparation method of positive electrode material, positive electrode and battery

Abstract

The invention relates to the technical field of battery materials, and discloses an iridium and praseodymium doped ternary precursor, a positive electrode material, a preparation method of the positive electrode material, a positive electrode and a battery. The iridium and praseodymium doped ternary precursor comprises an inner core and a coating layer, the inner core is formed by nickel-cobalt-manganese hydroxide doped with iridium, and the coating layer is formed by nickel-cobalt-manganese hydroxide doped with praseodymium; the chemical formula of the iridium and praseodymium doped ternary precursor is NixCoyMn1-x-y (OH) 2 [Ir] m [Pr] n, wherein x is greater than or equal to 0.34 and less than or equal to 0.9, y is greater than or equal to 0.05 and less than or equal to 0.33, and 1-x-y is greater than or equal to 0.05 and less than or equal to 0.33. The preparation method comprises the following steps: coprecipitating nickel ions, cobalt ions, manganese ions and iridium ions to obtain an inner core; and then nickel ions, cobalt ions, manganese ions and praseodymium ions are co-precipitated on the surface of the inner core to form a coating layer. The precursor provided by the invention has relatively good electrochemical performance.

Description

Technical Field

[0001] The present invention relates to the technical field of battery materials, and in particular to an iridium-praseodymium doped ternary precursor, a positive electrode material and a preparation method thereof, a positive electrode and a battery. Background Art

[0002] Nickel-cobalt-manganese ternary cathode material precursor is a commonly used material in lithium-ion batteries and is used to manufacture high-performance lithium-ion batteries. The main preparation method of the ternary precursor is to add nickel-cobalt-manganese metal salt solution, liquid alkali, and ammonia water to the reactor at the same time for coprecipitation reaction. Due to the limitations of equipment and process conditions, microcracks are easily generated during the nucleation process of the coprecipitation reaction. In order to better exert the excellent performance of the ternary cathode material, the performance of its precursor is crucial to the production of the ternary cathode material, because the quality of the precursor (morphology, particle size, particle size distribution, specific surface area, impurity content, tap density, etc.) directly determines the physical and chemical indicators of the final sintered product, resulting in the sintered ternary cathode material having average electrical properties, poor energy density and cycle performance.

[0003] In view of this, the present invention is proposed. Summary of the invention

[0004] The object of the present invention is to provide an iridium-praseodymium doped ternary precursor, a positive electrode material and a preparation method thereof, a positive electrode and a battery, aiming to improve at least one of the problems mentioned in the background technology.

[0005] The present invention is achieved in that: In a first aspect, the present invention provides an iridium-praseodymium doped ternary precursor, comprising a core and a coating layer; The core is nickel-cobalt-manganese hydroxide doped with iridium, and the coating layer is nickel-cobalt-manganese hydroxide doped with praseodymium. The particle size ratio of the core to the iridium-praseodymium doped ternary precursor is 0.6~0.8:1; the chemical formula of the iridium-praseodymium doped ternary precursor is Ni x Co y Mn 1-x-y (OH)2[Ir] m [Pr] n , where 0.34≤x≤0.9, 0.05≤y≤0.33, 0.05≤1-xy≤0.33, 0.0005≤m≤0.007, 0.0005≤n≤0.007.

[0006] In a second aspect, the present invention provides a method for preparing an iridium-praseodymium doped ternary precursor as described in the above embodiment, comprising: First, nickel ions, cobalt ions, manganese ions and iridium ions are coprecipitated to obtain the inner core; Then, nickel ions, cobalt ions, manganese ions and praseodymium ions are co-precipitated on the surface of the inner core to form a coating layer to obtain an iridium and praseodymium doped ternary precursor.

[0007] In an optional embodiment, the preparation method comprises: First co-precipitation: continuously adding a precipitant, a complexing agent and a first metal salt solution into a first reactor having a base liquid for co-precipitation, stopping the reaction when the particles in the first reactor grow to 60-80% of the target particle size, obtaining a first slurry, and extracting a solid material from the first slurry; Second co-precipitation: solid material, water, precipitant and complexing agent are added to the second reactor to prepare a bottom slurry, and then the precipitant, complexing agent and second metal salt solution are continuously added to the second reactor for co-precipitation until the particles grow to the target particle size and then the reaction is stopped to obtain a second slurry, and iridium and praseodymium doped ternary precursors are extracted from the second slurry; The first metal salt solution is a solution in which nickel, cobalt, manganese, or iridium ions are dissolved, or a solution in which nickel, cobalt, and manganese ions are dissolved and a solution in which iridium ions are dissolved; The second metal salt solution is a solution in which nickel, cobalt, manganese and praseodymium ions are dissolved, or a solution in which nickel, cobalt and manganese ions are dissolved and a solution in which praseodymium ions are dissolved.

[0008] In an optional embodiment, the complexing agent is ammonia water, the pH value of the base liquid is 11.5-12.5, and the ammonia value is 3-16 g / L; during the first coprecipitation process, the pH value in the first reaction kettle is controlled to be 10.8-11.6, and the ammonia value is 3-16 g / L; The pH value of the bottom slurry is 10.8~11.6, and the ammonia value is 3~16g / L; during the second co-precipitation process, the pH value in the second reactor is controlled to be 10.8~11.6, and the ammonia value is 3~16g / L.

[0009] In an optional embodiment, the method of configuring the base slurry includes: The solid material is mixed with water, and then a precipitant and a complexing agent are added to adjust the pH value of the slurry to 10.8-11.6 and the ammonia value to 3-16 g / L to obtain a base slurry with a solid content of 250-350 g / L; In an optional embodiment, at least one of the following features (1) to (5) is included: (1) The first metal salt solution is a solution containing nickel, cobalt, and manganese ions and a solution containing iridium ions; the second metal salt solution is a solution containing nickel, cobalt, and manganese ions and a solution containing praseodymium ions; The concentration of the solution containing nickel, cobalt and manganese ions is 1.8~2.2 mol / L, the concentration of the solution containing iridium ions is 0.1~1 mol / L, and the concentration of the solution containing praseodymium ions is 0.1~1 mol / L; During the first precipitation process, the addition rate of the solution containing nickel, cobalt and manganese ions is 100-800 L / h, and the addition rate of the solution containing iridium ions is 100-600 ml / min; During the second precipitation process, the addition rate of the solution containing nickel, cobalt and manganese ions is 100-800 L / h, and the addition rate of the solution containing praseodymium ions is 100-600 ml / min; (2) The reaction temperature of the first reactor and / or the second reactor is 40-70°C; (3) The method for extracting solid material from the first slurry includes: The first slurry is subjected to solid-liquid separation, and then free iridium on the solid material obtained by the solid-liquid separation is washed with pure water, and then dehydrated; (4) The method of extracting the iridium and praseodymium doped ternary precursor from the second slurry comprises: The second slurry is subjected to solid-liquid separation, and then free praseodymium on the solid material obtained by the solid-liquid separation is washed with pure water, and then dehydrated; (5) The precipitant is sodium hydroxide solution; the concentration of the sodium hydroxide solution is 5~12 mol / L.

[0010] In a third aspect, the present invention provides a method for preparing a positive electrode material, comprising mixing and sintering a lithium source and a ternary precursor as described in the aforementioned embodiment or a ternary precursor prepared by the preparation method of any one of the aforementioned embodiments.

[0011] In a fourth aspect, the present invention provides a positive electrode material, which is prepared using the ternary precursor of the aforementioned embodiment or the ternary precursor prepared by the preparation method of any one of the aforementioned embodiments as a raw material.

[0012] In a fifth aspect, the present invention provides a positive electrode, wherein the active material thereof includes the positive electrode material according to the aforementioned embodiment.

[0013] In a sixth aspect, the present invention provides a battery comprising a positive electrode as described in the aforementioned embodiment.

[0014] The present invention has the following beneficial effects: The iridium and praseodymium doped ternary precursor provided by the present invention directly incorporates the two elements of iridium and praseodymium into the precursor in a layered manner to improve the morphology, utilize the iridium element to improve the cycle stability and durability of the battery, extend the service life of the battery, and increase the energy density of the battery, utilize the praseodymium element to enhance the conductivity and electrochemical reaction activity, so that the precursor has a high tap density, is structurally stable, and has excellent energy density, electrochemical performance and cycle performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 This is a SEM image of the precursor prepared in Example 1; Figure 2 This is a SEM image of the precursor prepared in Example 2; Figure 3 This is a SEM image of the precursor prepared in Example 3; Figure 4 This is the SEM image of the precursor prepared in Comparative Example 1; Figure 5 This is the SEM image of the precursor prepared in Comparative Example 2; Figure 6 This is the SEM image of the precursor prepared in Comparative Example 3; Figure 7 This is the SEM image of the precursor prepared in Comparative Example 4. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0018] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0019] The iridium and praseodymium doped ternary precursor, positive electrode material and preparation method thereof, positive electrode and battery provided in the embodiments of the present invention are described in detail below.

[0020] The iridium-praseodymium doped ternary precursor provided in the embodiment of the present invention comprises a core and a coating layer; The core is nickel-cobalt-manganese hydroxide doped with iridium, the coating is nickel-cobalt-manganese hydroxide doped with praseodymium, and the particle size ratio of the core to the iridium-praseodymium doped ternary precursor is 0.6-0.8:1; The chemical formula of the ternary precursor doped with iridium and praseodymium is Ni x Co y Mn 1-x-y (OH)2[Ir] m [Pr] n, where 0.34≤x≤0.9, 0.05≤y≤0.33, 0.05≤1-xy≤0.33, 0.0005≤m≤0.007, 0.0005≤n≤0.007.

[0021] The atomic radius of iridium is larger than that of nickel, cobalt, manganese and other elements. Doping with iridium can change the electronic energy band structure and charge transfer path of the material, enhance the electronic conductivity and ion diffusion rate of the positive electrode material, help improve the electrochemical performance and stability of the material in the battery cycle, and reduce energy loss and electrode reactions in the cycle. Therefore, the use of iridium doping can improve the cycle stability and durability of the battery, reduce the capacity decay of the battery during the charge and discharge process, and extend the service life of the battery; improve the energy density of the battery, so that the battery can store more charge and provide a longer service time at the same volume or weight. However, when iridium is doped into the precursor lattice, it will cause lattice distortion and increase lattice stress. Lattice distortion will destroy the structural stability of the material, making it more prone to structural changes during the cycle, thereby causing ball cracking.

[0022] In response to the above problems, the present application dopes praseodymium outside the iridium-doped core. The atomic size and chemical properties of praseodymium are similar to those of nickel, cobalt, and manganese. The doping of praseodymium allows the ternary material precursor to form a solid solution. The praseodymium element will replace a portion of the cobalt and manganese atoms, which helps to optimize the crystal structure and make the crystal arrangement more orderly. At the same time, the formation of the solid solution can refine the grains and reduce crystal defects, thereby improving the stability and uniformity of the ternary positive electrode material. In addition, due to the existence of the solid solution, the elements inside the precursor can be evenly distributed, the heterogeneity of the main elements inside the precursor can be reduced, the internal stress caused by the difference in composition between the doped iridium element and nickel, cobalt, and manganese can be reduced, and the risk of ball cracking can be reduced. Therefore, the use of praseodymium doping can enhance conductivity and electrochemical reaction activity, help control the size and morphology of the precursor particles, improve the crystal structure of the material, and improve its stability and uniformity. Doping praseodymium in the precursor shell can reduce the occurrence of ball cracking in the precursor during the particle size growth process.

[0023] Therefore, the precursor provided by the present invention, due to the doping of iridium in the inner core and praseodymium in the outer layer, can have a higher tap density, higher structural stability, and excellent energy density and cycle performance.

[0024] The method for preparing an iridium-praseodymium doped ternary precursor provided in an embodiment of the present invention comprises: First, nickel ions, cobalt ions, manganese ions and iridium ions are coprecipitated to obtain the inner core; Then nickel ions, cobalt ions, manganese ions and praseodymium ions are co-precipitated on the surface of the inner core to form a coating layer to obtain an iridium and praseodymium doped ternary precursor.

[0025] The above preparation method provided by the embodiment of the present invention can produce the precursor provided by the embodiment of the present invention, which has an iridium-doped core and a praseodymium-doped outer layer with good electrochemical performance.

[0026] Preferably, in order to obtain a better performance of the precursor, the preparation method comprises: First co-precipitation: continuously adding a precipitant, a complexing agent and a first metal salt solution into a first reactor having a base liquid for co-precipitation, stopping the reaction when the particles in the first reactor grow to 60-80% of the target particle size, obtaining a first slurry, and extracting a solid material from the first slurry; Second co-precipitation: solid material, water, precipitant and complexing agent are added to the second reactor to prepare a bottom slurry, and then the precipitant, complexing agent and second metal salt solution are continuously added to the second reactor for co-precipitation until the particles grow to the target particle size and then the reaction is stopped to obtain a second slurry, and iridium and praseodymium doped ternary precursors are extracted from the second slurry; The first metal salt solution is a solution in which nickel, cobalt, manganese and iridium ions are dissolved (i.e., nickel, cobalt, manganese and iridium ions are dissolved together in the same solution), or a solution in which nickel, cobalt and manganese ions are dissolved and a solution in which iridium ions are dissolved (i.e., iridium ions are dissolved alone in another solution); The second metal salt solution is a solution containing nickel, cobalt, manganese and praseodymium ions (i.e., nickel, cobalt, manganese and praseodymium ions are dissolved together in the same solution), or a solution containing nickel, cobalt and manganese ions and a solution containing praseodymium ions (i.e., praseodymium ions are dissolved alone in another solution).

[0027] The preparation method is as follows: S1. Prepare liquid A solution (ternary solution) containing nickel, cobalt and manganese ions at a concentration of 1.8 to 2.2 mol / L (e.g., 1.8 mol / L, 2 mol / L or 2.2 mol / L) is prepared using nickel-cobalt-manganese salt crystals; Use sodium hydroxide dissolved in deionized water to prepare a 5-12 mol / L (e.g., 5 mol / L, 8 mol / L, 10 mol / L or 12 mol / L) liquid alkali solution as a precipitant; Use ammonia water with a mass concentration of 15-25% (e.g., 15%, 20% or 25%) as a complexing agent; Dissolving a soluble iridium salt in deionized water to prepare a solution containing iridium ions at a concentration of 0.1 to 1 mol / L (e.g., 0.1 mol / L, 0.3 mol / L, 0.8 mol / L, or 1 mol / L); A soluble praseodymium salt is dissolved in deionized water to prepare a praseodymium ion-containing solution having a concentration of 0.1 to 1 mol / L (eg, 0.1 mol / L, 0.3 mol / L, 0.8 mol / L or 1 mol / L).

[0028] Optionally, the metal salt involved in the above content can be at least one of soluble salts such as hydrochloride, sulfate, nitrate, etc.

[0029] S2, first precipitation Add 5-8m³ (e.g., 5m³, 6m³ or 8m³) of pure water into the first reaction kettle, add ammonia water and liquid alkali to adjust the ammonia value to 3-16g / L and the pH value to 11.5-12.5 to obtain a base liquid. When preparing the base liquid, introduce 1-10m³ / h of nitrogen for atmosphere replacement, and use it as a protective gas for the subsequent precipitation process.

[0030] After the preparation of the base liquid is completed, the ternary liquid, ammonia water and liquid alkali are added to the first reactor through a metering pump, and the solution containing iridium ions is added using a peristaltic pump. The temperature of the reactor is set to 40~70℃ (for example, 40℃, 50℃, 60℃ or 70℃), the speed of the stirring blade is 200~600r / min (for example, 200r / min, 400r / min or 600r / min), the flow rate of the ternary liquid is 100~800L / h (for example, 100L / h, 400L / h, 600L / h or 800L / h), and the flow rate of the solution containing iridium ions is 100~600ml / min (for example, 100ml / min, 400ml / min or 600ml / min). During the reaction, the pH in the reactor is controlled to be 10.8~11.6, and the ammonia value is 3~16g / L.

[0031] When it is detected that the particles in the reactor have grown to 60-80% (e.g., 60%, 70% or 80%) of the target particle size, the reaction is stopped to obtain the first slurry, the first slurry is placed in an aging tank and directly pumped to a centrifuge for washing, 1-3 m³ of pure water is added to rinse the residual iridium ions on the surface of the material, and the material is dried to obtain a solid material.

[0032] S3, second precipitation The solid material is added to the second reactor, and then pure water is added to the second reactor to prepare a slurry with a solid content of 100-500 g / L (e.g., 100 g / L, 300 g / L or 500 g / L) and a slurry volume of 3-8 m 3 (For example, 3m³, 8m³ or 8m³). Then, liquid alkali and ammonia water are added to the slurry to readjust the pH of the slurry to 10.8~11.60, the ammonia value to 3~16g / L, and the solid content of the slurry is adjusted to 250~350g / L to obtain the bottom slurry.

[0033] After the bottom slurry is prepared, the feed of ternary liquid, ammonia water and liquid alkali is resumed, and the solution containing praseodymium ions is introduced into the second reactor at the same time. The flow rate of the solution containing iridium ions is 100-600 ml / min (e.g., 100 ml / min, 300 ml / min or 600 ml / min). When the D50 of the particles in the second reactor is detected to grow to 4-14 μm (e.g., 4 μm, 6 μm, 8 μm, 10 μm or 14 μm), the slurry is placed in an aging tank, pumped to a centrifuge for washing and dehydration, and finally dried to obtain a ternary precursor doped with praseodymium and iridium in layers.

[0034] It should be noted that the first reactor and the second reactor can be the same reactor, and the first reactor is cleaned after the first precipitation and used as the second reactor after cleaning. The second reactor and the second reactor can also be different reactors.

[0035] It should be noted that, in addition to the specific contents recorded above, the control methods such as the addition rate of each feed liquid, the pH value in the reactor, the ammonia value, etc. in the co-precipitation process can also refer to the existing technology, and the control method of the co-precipitation process of the existing conventional ternary precursor preparation process can also be used to prepare the precursor of the present application.

[0036] The method for preparing the positive electrode material provided by the embodiment of the present invention comprises mixing and sintering a lithium source and a ternary precursor provided by the embodiment of the present invention or a ternary precursor prepared by the preparation method provided by the embodiment of the present invention.

[0037] Optionally, the lithium source is lithium hydroxide or lithium carbonate.

[0038] The positive electrode material provided by the embodiment of the present invention is prepared using the ternary precursor provided by the embodiment of the present invention or the ternary precursor prepared by the preparation method provided by the embodiment of the present invention as a raw material.

[0039] The positive electrode provided by the embodiment of the present invention, wherein the active material thereof includes the positive electrode material provided by the embodiment of the present invention.

[0040] The battery provided by the embodiment of the present invention includes the positive electrode provided by the embodiment of the present invention.

[0041] Example 1 The iridium and praseodymium doped ternary precursor provided in this embodiment has a ratio of core to ternary precursor of 0.74:1, and the chemical formula is Ni 0.55 Co 0.15 Mn 0.30 (OH)2[Ir] 0.005 [Pr] 0.005 .

[0042] The preparation method is specifically as follows: Prepare the liquid: Nickel sulfate, cobalt sulfate and manganese sulfate were dissolved in deionized water at a ratio of 55.3:14.9:29.8 to obtain a ternary liquid with a concentration of 2.02 mol / L; sodium hydroxide was dissolved in deionized water to prepare a 10.8 mol / L liquid alkali solution as a precipitant; ammonia water with a mass concentration of 21% was used as a complexing agent; iridium nitrate was dissolved in deionized water to obtain an iridium salt solution with a concentration of 0.5 mol / L; praseodymium sulfate was dissolved in deionized water to obtain a praseodymium salt solution with a concentration of 0.5 mol / L.

[0043] First precipitation: Add 7m 3 Pure water was heated to 65°C, and ammonia water and liquid alkali were added to adjust the ammonia value to 8±0.5g / L and the pH value to 11.90±0.05 to obtain the base liquid. When preparing the base liquid, 5m 3 / h of nitrogen.

[0044] After the preparation of the base liquid is completed, the ternary liquid, ammonia water and liquid alkali are added to the reactor through a metering pump, and the iridium salt solution is added using a peristaltic pump. The temperature of the reactor is maintained at 65°C, the speed of the stirring blade is 300r / min, the flow rate of the ternary liquid is 200L / h, the liquid alkali is added at a flow rate of 133L / h, the ammonia water is added at a flow rate of 42L / h, and the iridium salt solution is added at a flow rate of 300ml / min using a peristaltic pump. During the reaction, a thickener is used to concentrate and clear. At the beginning of the reaction, the pH is maintained in the range of 11.90±0.05 for 2h. After 2h, the pH is reduced to 11.40 at a rate of 0.1 / h and maintained. In the 7th hour, the flow rate of the ternary liquid is increased to 400L / h, and the ammonia and alkali flow rate is adjusted synchronously. The nitrogen flow rate is reduced according to the color of the slurry to keep the slurry color light yellow.

[0045] After reacting in the reactor for 39 hours, the particle size D50 grew to 4.5μm and the feeding was stopped. The material was placed in the aging tank, and the reactor was rinsed with pure water. The slurry was pumped into a centrifuge, and the mother liquor was first dried at high speed. Then 2m³ of pure water was added at a rate of 2m³ / h for rinsing and dehydration for 3 hours to obtain solid material. The solid material was placed in a barrel for standby use.

[0046] Second precipitation: Add 7m 3 Pure water was continuously introduced into the reactor for 5 m 3 / h of nitrogen, add 1400kg of solid material into the reactor, adjust the solid content to 200g / L, continue to add liquid alkali and ammonia water to adjust the pH to 11.40±0.05, the ammonia value to 8±0.5g / L, the temperature of the reactor is increased to 65℃, the stirring speed is 300r / min, after the adjustment is completed, add 2.02mol / L of ternary liquid at a flow rate of 200L / h, add 32% liquid alkali solution at a flow rate of 113L / h, add 21% ammonia solution at a flow rate of 42L / h, use a peristaltic pump to add praseodymium salt solution at a flow rate of 400ml / min, use a thickener to concentrate and clear during the reaction, after 2h of reaction, the flow rate of the ternary liquid is increased to 400L / h and maintained. After 81h of reaction, it is detected that the particle size has grown to D50 of 6.1μm, and the feeding is stopped. The ternary precursor slurry is washed with impurities, filtered, dehydrated and dried to obtain a layered doped ternary precursor.

[0047] The SEM image of the prepared ternary precursor is shown in Figure 1 As shown in the figure, it can be seen that the surface of the precursor is smoother and the sphericity is better.

[0048] Example 2 The iridium and praseodymium doped ternary precursor provided in this embodiment has a ratio of core to ternary precursor of 0.69:1, and the chemical formula is Ni 0.83 Co 0.11 Mn 0.06 (OH)2[Ir] 0.007 [Pr] 0.003 .

[0049] The preparation method is specifically as follows: Prepare the liquid: Nickel sulfate, cobalt sulfate and manganese sulfate were dissolved in deionized water at a ratio of 83:11:6 to obtain a ternary liquid with a concentration of 2.02 mol / L; sodium hydroxide was dissolved in deionized water to prepare a 10.8 mol / L liquid alkali solution as a precipitant; ammonia water with a mass concentration of 21% was used as a complexing agent; iridium nitrate was dissolved in deionized water to obtain an iridium salt solution with a concentration of 0.5 mol / L; praseodymium sulfate was dissolved in deionized water to obtain a praseodymium salt solution with a concentration of 0.5 mol / L.

[0050] First precipitation: Add 7m 3 Pure water was heated to 60°C, and ammonia water and liquid alkali were added to adjust the ammonia value to 6±0.5g / L and the pH value to 11.55±0.05 to obtain the base liquid. When preparing the base liquid, 3m 3 / h of nitrogen.

[0051] After the preparation of the base liquid is completed, the ternary liquid, ammonia water and liquid alkali are added to the first reactor through a metering pump, and the iridium salt solution is added using a peristaltic pump. The temperature of the reactor is maintained at 60°C, the speed of the stirring blade is 260r / min, the flow rate of the ternary liquid is 180L / h, the liquid alkali is added at a flow rate of 86L / h, the ammonia water is added at a flow rate of 38L / h, and the iridium salt solution is added at a flow rate of 300ml / min using a peristaltic pump. During the reaction process, a thickener is used to concentrate and clear. At the beginning of the reaction, the pH was maintained at 11.55±0.05 for 4 hours. After 4 hours, the pH was reduced to 10.95±0.05 at a rate of 0.1 / h and then maintained. In the 4th hour, the flow rate of the ternary liquid was increased to 400L / h and maintained. In the 12th hour, the flow rate of the ternary liquid was increased to 600L / h and maintained. When adjusting the flow rate of the ternary liquid, the flow rate of ammonia and alkali was adjusted synchronously to keep the ammonia value stable at 6±0.5g / L and the pH at 10.95±0.05. In the 12th hour, nitrogen with a purity of 99.99% was introduced at a flow rate of 3m³ / h. When the particle size grew to 7μm, the nitrogen flow rate was reduced to 1m 3 / h.

[0052] After reacting in the reactor for 86 hours, the particle size D50 grows to 7.5μm and the feeding is stopped. After the material is placed in the aging tank, the reactor is rinsed with pure water, and the slurry is pumped into a centrifuge. The mother liquor is first dried at high speed, and then 2m³ of pure water is added at a rate of 2m³ / h for rinsing and dehydration for 1h to obtain a solid material, which is placed in a barrel for standby use.

[0053] Second precipitation: Add 7m 3 Pure water, and at the same time, 3m³ / h nitrogen protection was introduced. 2100kg of solid material was added to the reactor, and the solid content was adjusted to 300g / L. Liquid alkali and ammonia water were continued to be added to adjust the pH to 10.95±0.05, and the ammonia value was 6±0.5g / L. The temperature of the reactor was raised to 60℃, and the stirring speed was 200r / min. After the adjustment was completed, 2.05mol / L nickel-cobalt-manganese solution was added at a flow rate of 180L / h, and 3 at a flow rate of 86L / h. A 2% liquid alkali solution and a 21% ammonia solution were added at a flow rate of 38 L / h. A peristaltic pump was used to add praseodymium salt solution at a flow rate of 300 ml / min. A thickener was used to concentrate and clear the solution during the reaction. After 2 hours of reaction, the flow rate of nickel cobalt manganese salt was increased to 600 L / h and maintained. After 124 hours of reaction, the particle size growth to D50 of 10.8 μm was detected, and the feeding was stopped. The ternary precursor slurry was washed with impurities, filtered, dehydrated and dried to obtain a layered doped ternary precursor.

[0054] The SEM image of the prepared ternary precursor is shown in Figure 2 As shown in the figure, it can be seen that there are no cracks on the surface of the precursor, and the surface is smooth and the sphericity is good.

[0055] Example 3 This embodiment is basically the same as embodiment 1, except that the entire precipitation process is not stopped, and the doping solution is directly switched. The details are as follows: Add 7m 3 Pure water was heated to 65°C, the stirring blade inside the reactor was operated at a speed of 300r / min, and then the prepared liquid alkali solution was added to adjust the pH to 11.90±0.05, and ammonia solution was added to adjust the bottom liquid ammonia value to 8±0.5g / L, and 5m 3 / h of nitrogen for nitrogen protection. Then add 2.02mol / L ternary liquid at a flow rate of 200L / h, add 32% liquid alkali solution at a flow rate of 113L / h, add 21% ammonia solution at a flow rate of 42L / h, use a peristaltic pump to add iridium salt solution at a flow rate of 300ml / min, and use a thickener to concentrate and clear during the reaction; at the beginning of the reaction, the pH is maintained in the range of 11.90±0.05 for 2h, and after 2h, the pH is reduced to 11.40 at a rate of 0.1 / h and maintained. In the 7th hour, the flow rate of the ternary liquid is increased to 400L / h and maintained, and the flow rate of ammonia and alkali is adjusted simultaneously. 7 hours before the reaction, the pH is maintained at 5m 3 / h of nitrogen with a purity of 99.99%. The nitrogen flow rate was subsequently reduced according to the color of the slurry to keep the slurry color light yellow.

[0056] After reacting in the reactor for 53 hours, the particle size D50 grows to 4.5 μm and the iridium salt solution is stopped. A peristaltic pump is used to introduce praseodymium salt solution at a flow rate of 300 ml / min. After reacting for 76 hours, the particle size grows to 6-6.5 μm and the feeding is stopped. The ternary precursor slurry is washed with impurities, filtered, dehydrated and dried to obtain the doped ternary precursor.

[0057] The SEM image of the prepared ternary precursor is shown in Figure 3 As shown in the figure, it can be seen that there are no cracks on the surface of the precursor.

[0058] Example 4 This embodiment is basically the same as Embodiment 1, except that the ratio of the core to the ternary precursor doped with iridium and praseodymium is 0.6:1. The preparation method is specifically as follows: Prepare the liquid: Nickel sulfate, cobalt sulfate and manganese sulfate were dissolved in deionized water at a ratio of 55.3:14.9:29.8 to obtain a ternary liquid with a concentration of 2.02 mol / L; sodium hydroxide was dissolved in deionized water to prepare a 10.8 mol / L liquid alkali solution as a precipitant; ammonia water with a mass concentration of 21% was used as a complexing agent; iridium nitrate was dissolved in deionized water to obtain an iridium salt solution with a concentration of 0.5 mol / L; praseodymium sulfate was dissolved in deionized water to obtain a praseodymium salt solution with a concentration of 0.5 mol / L.

[0059] First precipitation: Add 7m 3 Pure water was heated to 65°C, and ammonia water and liquid alkali were added to adjust the ammonia value to 8±0.5g / L and the pH value to 11.90±0.05 to obtain the base liquid. When preparing the base liquid, 5m 3 / h of nitrogen.

[0060] After the preparation of the base liquid is completed, the ternary liquid, ammonia water and liquid alkali are added to the reactor through a metering pump, and the iridium salt solution is added using a peristaltic pump. The temperature of the reactor is maintained at 65°C, the speed of the stirring blade is 300r / min, the flow rate of the ternary liquid is 200L / h, the liquid alkali is added at a flow rate of 133L / h, the ammonia water is added at a flow rate of 42L / h, and the iridium salt solution is added at a flow rate of 300ml / min using a peristaltic pump. During the reaction, a thickener is used to concentrate and clear. At the beginning of the reaction, the pH is maintained in the range of 11.90±0.05 for 2h. After 2h, the pH is reduced to 11.40 at a rate of 0.1 / h and maintained. In the 7th hour, the flow rate of the ternary liquid is increased to 400L / h, and the ammonia and alkali flow rate is adjusted synchronously. The nitrogen flow rate is reduced according to the color of the slurry to keep the slurry color light yellow.

[0061] After reacting in the reactor for 39 hours, the particle size D50 grew to 3.66μm and the feeding was stopped. The material was placed in the aging tank, and the reactor was rinsed with pure water. The slurry was pumped into a centrifuge, and the mother liquor was first dried at high speed. Then 2m³ of pure water was added at a rate of 2m³ / h for rinsing and dehydration for 3 hours to obtain a solid material, which was placed in a barrel for standby use.

[0062] Second precipitation: Add 7m 3 Pure water was continuously introduced into the reactor for 5 m 3 / h of nitrogen, add 1400kg of solid material into the reactor, adjust the solid content to 200g / L, continue to add liquid alkali and ammonia water to adjust the pH to 11.40±0.05, the ammonia value is 8±0.5g / L, the temperature of the reactor is increased to 65℃, the stirring speed is 300r / min, after the adjustment is completed, add 2.02mol / L of ternary liquid at a flow rate of 300L / h, add 32% liquid alkali solution at a flow rate of 113L / h, add 21% ammonia solution at a flow rate of 42L / h, use a peristaltic pump to add praseodymium salt solution at a flow rate of 500ml / min, use a thickener to concentrate and clear during the reaction, after 2h of reaction, the flow rate of the ternary liquid is increased to 400L / h and maintained. After 81h of reaction, it is detected that the particle size has grown to D50 of 6.1μm, and the feeding is stopped. The ternary precursor slurry is washed with impurities, filtered, dehydrated and dried to obtain a layered doped ternary precursor.

[0063] Example 5 This embodiment is basically the same as Embodiment 1, except that the ratio of the core to the ternary precursor doped with iridium and praseodymium is 0.8:1. The specific preparation method is: Prepare the liquid: Nickel sulfate, cobalt sulfate and manganese sulfate were dissolved in deionized water at a ratio of 55.3:14.9:29.8 to obtain a ternary liquid with a concentration of 2.02 mol / L; sodium hydroxide was dissolved in deionized water to prepare a 10.8 mol / L liquid alkali solution as a precipitant; ammonia water with a mass concentration of 21% was used as a complexing agent; iridium nitrate was dissolved in deionized water to obtain an iridium salt solution with a concentration of 0.5 mol / L; praseodymium sulfate was dissolved in deionized water to obtain a praseodymium salt solution with a concentration of 0.5 mol / L.

[0064] First precipitation: Add 7m 3 Pure water was heated to 65°C, and ammonia water and liquid alkali were added to adjust the ammonia value to 8±0.5g / L and the pH value to 11.90±0.05 to obtain the base liquid. When preparing the base liquid, 5m 3 / h of nitrogen.

[0065] After the preparation of the base liquid is completed, the ternary liquid, ammonia water and liquid alkali are added to the reactor through a metering pump, and the iridium salt solution is added using a peristaltic pump. The temperature of the reactor is maintained at 65°C, the speed of the stirring blade is 300r / min, the flow rate of the ternary liquid is 200L / h, the liquid alkali is added at a flow rate of 126L / h, the ammonia water is added at a flow rate of 40L / h, and the iridium salt solution is added at a flow rate of 150ml / min using a peristaltic pump. During the reaction, a thickener is used to concentrate and clear. At the beginning of the reaction, the pH is maintained in the range of 11.90±0.05 for 2h. After 2h, the pH is reduced to 11.40 at a rate of 0.1 / h and maintained. In the 7th hour, the flow rate of the ternary liquid is increased to 400L / h, and the ammonia and alkali flow rate is adjusted synchronously. The nitrogen flow rate is reduced according to the color of the slurry to keep the slurry color light yellow.

[0066] After reacting in the reactor for 39 hours, the particle size D50 grew to 4.88μm and the feeding was stopped. The material was placed in the aging tank, and the reactor was rinsed with pure water. The slurry was pumped into a centrifuge, and the mother liquor was first dried at high speed. Then 2m³ of pure water was added at a rate of 2m³ / h for rinsing and dehydration for 3 hours to obtain solid material. The solid material was placed in a barrel for standby use.

[0067] Second precipitation: Add 7m 3 Pure water was continuously introduced into the reactor for 5 m 3 / h of nitrogen, add 1400kg of solid material into the reactor, adjust the solid content to 200g / L, continue to add liquid alkali and ammonia water to adjust the pH to 11.40±0.05, the ammonia value to 8±0.5g / L, the temperature of the reactor is increased to 65℃, the stirring speed is 300r / min, after the adjustment is completed, add 2.02mol / L of ternary liquid at a flow rate of 400L / h, add 32% liquid alkali solution at a flow rate of 120L / h, add 21% ammonia solution at a flow rate of 42L / h, use a peristaltic pump to add praseodymium salt solution at a flow rate of 600ml / min, use a thickener to concentrate and clear during the reaction, after 2h of reaction, the flow rate of the ternary liquid is increased to 400L / h and maintained. After 81h of reaction, it is detected that the particle size has grown to D50 of 6.1μm, and the feeding is stopped. The ternary precursor slurry is washed with impurities, filtered, dehydrated and dried to obtain a layered doped ternary precursor.

[0068] Example 6 This embodiment is basically the same as embodiment 1, except that: the chemical formula is Ni 0.34 Co 0.33 Mn 0.33 (OH)2[Ir] 0.0005 [Pr] 0.0005 .

[0069] The preparation method is specifically as follows: Prepare the liquid: Nickel sulfate, cobalt sulfate and manganese sulfate were dissolved in deionized water at a ratio of 34:33:33 to obtain a ternary liquid with a concentration of 2.0 mol / L; sodium hydroxide was dissolved in deionized water to prepare a 10.8 mol / L liquid alkali solution as a precipitant; ammonia water with a mass concentration of 21% was used as a complexing agent; iridium nitrate was dissolved in deionized water to obtain an iridium salt solution with a concentration of 0.5 mol / L; praseodymium sulfate was dissolved in deionized water to obtain a praseodymium salt solution with a concentration of 0.5 mol / L.

[0070] First precipitation: Add 7m 3 Pure water was heated to 50°C, and ammonia water and liquid alkali were added to adjust the ammonia value to 3.5±0.5g / L and the pH value to 12.15±0.05 to obtain the base liquid. When preparing the base liquid, 5m 3 / h of nitrogen.

[0071] After the preparation of the base liquid is completed, the ternary liquid, ammonia water and liquid alkali are added to the first reactor through a metering pump, and the iridium salt solution is added using a peristaltic pump. The temperature of the reactor is maintained at 60°C, the speed of the stirring blade is 290r / min, the flow rate of the ternary liquid is 600L / h, the liquid alkali is added at a flow rate of 325L / h, the ammonia water is added at a flow rate of 183L / h, and the iridium salt solution is added at a flow rate of 45ml / min using a peristaltic pump. During the reaction, a thickener is used to concentrate and clear. At the beginning of the reaction, the pH is maintained in the range of 12.15±0.05 for 6h. After 6h, the pH is reduced to 11.55±0.05 at a rate of 0.1 / h and maintained. Nitrogen with a purity of 99.99% is introduced at a flow rate of 5m³ / h.

[0072] After reacting in the reactor for 63 hours, the particle size D50 grew to 2.15μm and the feeding was stopped. The material was placed in the aging tank, the reactor was rinsed with pure water, the slurry was pumped into the centrifuge, the mother liquor was first dried at high speed, and then 2m³ of pure water was added at a rate of 2m³ / h for rinsing and dehydration for 1h to obtain solid material, which was placed in a barrel for standby use.

[0073] Second precipitation: Add 7m 3Pure water, and at the same time, 3m³ / h nitrogen protection was introduced. 2100kg of solid material was added to the reactor, and the solid content was adjusted to 300g / L. Liquid alkali and ammonia water were continued to be added to adjust the pH to 11.55±0.05, and the ammonia value was 4±0.5g / L. The temperature of the reactor was raised to 50℃, and the stirring speed was 290r / min. After the adjustment was completed, 2.0mol / L nickel-cobalt-manganese solution was added at a flow rate of 200L / h, and 32% liquid alkali was added at a flow rate of 109L / h. Solution, 21% ammonia solution was added at a flow rate of 61L / h, praseodymium salt solution was added at a flow rate of 45ml / min using a peristaltic pump, and a thickener was used to concentrate and clear the reaction. After 8h of reaction, the flow rate of nickel, cobalt and manganese salt was increased to 400L / h, and the flow rate of the ternary liquid was increased to 600L / h in the 15th hour. When the particle size grew to D50 of 4.3μm, the feeding was stopped, and the ternary precursor slurry was washed with impurities, filtered, dehydrated and dried to obtain a layered doped ternary precursor.

[0074] Comparative Example 1 This embodiment is basically the same as the embodiment 1, except that there is no doping. The details are as follows: Add 7m 3 Pure water was heated to 65°C, the stirring blade inside the reactor was operated at a speed of 300r / min, and then the prepared liquid alkali solution was added to adjust the pH to 11.90±0.05, and the ammonia solution was added to adjust the bottom liquid ammonia value to 8±0.5g / L, and 5m 3 / h of nitrogen. Then add 2.02mol / L ternary liquid at a flow rate of 200L / h, add 32% liquid alkali solution at a flow rate of 113L / h, and add 21% ammonia solution at a flow rate of 42L / h. Use a thickener to concentrate and clear the reaction. At the beginning of the reaction, the pH is maintained in the range of 11.90±0.05 for 2h. After 2h, the pH is reduced to 11.40 at a rate of 0.1 / h and maintained. In the 7th hour, the flow rate of the ternary liquid is increased to 400L / h and maintained. The flow rate of ammonia and alkali is adjusted simultaneously. 7 hours before the reaction, the pH is maintained at 5m 3 / h of nitrogen with a purity of 99.99%. The nitrogen flow rate was subsequently reduced according to the color of the slurry to keep the slurry color light yellow. After 83 hours of reaction, the particle size grew to D50 of 6.1μm, and the feeding was stopped. The ternary precursor slurry was washed with impurities, filtered, dehydrated and dried to obtain the ternary precursor.

[0075] The SEM image of the prepared ternary precursor is shown in Figure 4 As shown in the figure, it can be seen that the morphology is rougher than that of Example 1 and the sphericity is poor.

[0076] Comparative Example 2 This embodiment is basically the same as the embodiment 1, except that there is no praseodymium doping. Add 7m 3 Pure water was heated to 65°C, the stirring blade inside the reactor was operated at a speed of 300r / min, and then the prepared liquid alkali solution was added to adjust the pH to 11.90±0.05, and ammonia solution was added to adjust the bottom liquid ammonia value to 8±0.5g / L, and 5m 3 / h of nitrogen for nitrogen protection. Then add 2.02mol / L ternary liquid at a flow rate of 200L / h, add 32% liquid alkali solution at a flow rate of 113L / h, add 21% ammonia solution at a flow rate of 42L / h, use a peristaltic pump to add iridium salt solution at a flow rate of 300ml / min, and use a thickener to concentrate and clear during the reaction; at the beginning of the reaction, the pH is maintained in the range of 11.90±0.05 for 2h, and after 2h, the pH is reduced to 11.40 at a rate of 0.1 / h and maintained. In the 7th hour, the flow rate of the ternary liquid is increased to 400L / h and maintained, and the flow rate of ammonia and alkali is adjusted simultaneously. 7 hours before the reaction, the pH is maintained at 5m 3 / h flow rate of 99.99% pure nitrogen, and then reduce the nitrogen flow rate according to the color of the slurry to keep the slurry color light yellow. After 78h of reaction in the reactor, the particle size grows to D50 of 6.1μm, and the feeding is stopped. The ternary precursor slurry is washed with impurities, filtered, dehydrated, and dried to obtain the doped ternary precursor.

[0077] The SEM image of the prepared ternary precursor is shown in Figure 5 As shown in the figure, it can be seen that the morphology is rougher than that of Example 1, the primary particles are mixed with coarse and fine particles, grow irregularly, and have a higher porosity.

[0078] Comparative Example 3 This embodiment is basically the same as the embodiment 1, except that there is no iridium doping. The details are as follows: Add 7m 3 Pure water was heated to 65°C, the stirring blade inside the reactor was operated at a speed of 300r / min, and then the prepared liquid alkali solution was added to adjust the pH to 11.90±0.05, and ammonia solution was added to adjust the bottom liquid ammonia value to 8±0.5g / L, and 5m 3 / h of nitrogen for nitrogen protection. Then add 2.02mol / L ternary liquid at a flow rate of 200L / h, add 32% liquid alkali solution at a flow rate of 113L / h, add 21% ammonia solution at a flow rate of 42L / h, use a peristaltic pump to add praseodymium salt solution at a flow rate of 300ml / min, and use a thickener to concentrate and clear during the reaction; at the beginning of the reaction, the pH is maintained in the range of 11.90±0.05 for 2h, and after 2h, the pH is reduced to 11.40 at a rate of 0.1 / h and maintained. In the 7th hour, the flow rate of the ternary liquid is increased to 400L / h and maintained, and the flow rate of ammonia and alkali is adjusted simultaneously. 7 hours before the reaction, the pH is maintained at 5m 3 / h of nitrogen with a purity of 99.99%. Subsequently, the nitrogen flow rate was reduced according to the color of the slurry to keep the color of the slurry light yellow. After 84 hours of reaction, the particle size grew to 6-6.5μm and the feeding was stopped. The ternary precursor slurry was washed with impurities, filtered, dehydrated and dried to obtain the doped ternary precursor.

[0079] The SEM image of the prepared ternary precursor is shown in Figure 6 As shown in the figure, it can be seen that the sphericity of the morphology is relatively good.

[0080] Comparative Example 4 This embodiment is basically the same as embodiment 2, except that there is no praseodymium doping. The preparation method is specifically as follows: Prepare the liquid: Nickel sulfate, cobalt sulfate and manganese sulfate were dissolved in deionized water at a ratio of 83:11:6 to obtain a ternary liquid with a concentration of 2.02 mol / L; sodium hydroxide was dissolved in deionized water to prepare a 10.8 mol / L liquid alkali solution as a precipitant; ammonia water with a mass concentration of 21% was used as a complexing agent; iridium nitrate was dissolved in deionized water to obtain an iridium salt solution with a concentration of 0.5 mol / L; the first precipitation: Add 7m 3 Pure water was heated to 60°C, and ammonia water and liquid alkali were added to adjust the ammonia value to 6±0.5g / L and the pH value to 11.55±0.05 to obtain the base liquid. When preparing the base liquid, 3m 3 / h of nitrogen.

[0081] After the base liquid is prepared, the ternary liquid, ammonia water and liquid alkali are added to the first reactor through a metering pump, and the iridium salt solution is added using a peristaltic pump. The reactor temperature is maintained at 60°C, the speed of the stirring blade is 260r / min, the flow rate of the ternary liquid is 180L / h, the liquid alkali is added at a flow rate of 86L / h, the ammonia water is added at a flow rate of 38L / h, and the iridium salt solution is added at a flow rate of 30ml / min using a peristaltic pump. During the reaction process, a thickener is used to concentrate and clear. At the beginning of the reaction, the pH was maintained in the range of 11.55±0.05 for 4 hours. After 4 hours, the pH was reduced to 10.95±0.05 at a rate of 0.1 / h and then maintained. In the 4th hour, the flow rate of the ternary liquid was increased to 400L / h and maintained. In the 12th hour, the flow rate of the ternary liquid was increased to 600L / h and maintained. When adjusting the flow rate of the ternary liquid, the flow rate of ammonia and alkali was adjusted synchronously to keep the ammonia value stable at 6±0.5g / L and the pH at 10.95±0.05. In the 12th hour, nitrogen with a purity of 99.99% was introduced at a flow rate of 3m³ / h. After 95 hours of reaction, when the particle size grew to 10.8μm, the feeding was stopped, and the ternary precursor slurry was washed with impurities, filtered, dehydrated, and dried to obtain the ternary precursor doped with iridium.

[0082] The SEM image of the prepared ternary precursor is shown in Figure 7 As shown in the figure, it can be seen that there are cracks on the surface of the precursor.

[0083] Experimental example The tap density of the precursors prepared in each embodiment and comparative example was tested and recorded in Table 1.

[0084] The precursors prepared in various embodiments and comparative examples were made into positive electrode materials and then prepared into batteries, and their electrochemical properties were measured and recorded in Table 1.

[0085] Electrochemical performance test method: 1. The precursors prepared in the embodiment and comparative example and lithium hydroxide were uniformly mixed in a molar ratio of M(Ni+Co+Mn):M(Li)=1:1.03, pre-calcined at 450°C for 4h, taken out and ground, calcined at 750°C for 20h, and finally taken out and crushed to obtain a positive electrode material; 2. The obtained positive electrode material is prepared into a slurry according to the ratio of positive electrode material: conductive carbon: polyvinylidene fluoride (PVDF) = 90:5:5, and made into a positive electrode sheet (the compaction density of the electrode sheet is 3.3g / cm³), and a metal lithium sheet is selected as the negative electrode material to assemble into a 2025 button battery; 3. Using 1M LiPF6 EC:DEC:DMC=1:1:1 (V%) as the electrolyte, after three cycles of activation at 0.2C rate, cycle 100 times at 0.2C rate, measure the discharge capacity at the 1st cycle and the discharge capacity at the 100th cycle, and calculate the capacity retention rate after 100 cycles; Table 1 Performance of the precursors of various embodiments and comparative examples

[0086] It can be seen from Table 1 that the precursors prepared in various embodiments of the present invention have a relatively high tap density and have better electrochemical performance after being made into batteries.

[0087] Comparing Example 1 with Comparative Examples 1, 2, and 3, Example 1 has a higher tap density, and the first discharge capacity and capacity retention rate of the prepared battery are significantly improved, indicating that simultaneous doping of iridium and praseodymium can significantly improve the electrochemical performance of the precursor.

[0088] Comparing Examples 1 and 3 with the comparative examples, the various properties of Example 3 are slightly worse than those of Example 1, but better than those of the comparative examples, indicating that when preparing iridium and praseodymium doped ternary precursors, the method of stopping the machine and preparing in steps can achieve better results than continuous preparation.

[0089] Comparing Example 2 with Comparative Example 4, the precursor prepared in Comparative Example 4 has cracks due to the absence of praseodymium doping, indicating that the doping of praseodymium can improve the situation of ball cracking of the precursor during the particle size growth process.

[0090] In summary, the iridium and praseodymium doped ternary precursor provided in the embodiment of the present invention directly incorporates the two elements of iridium and praseodymium into the precursor in a layered manner to improve the morphology, and utilizes the iridium element to improve the cycle stability and durability of the battery, extend the service life of the battery, and increase the energy density of the battery. The praseodymium element is utilized to enhance the conductivity and electrochemical reaction activity, so that the precursor has a high tap density, is structurally stable, and has excellent energy density, electrochemical properties, and cycle performance.

[0091] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An iridium-praseodymium doped ternary precursor, characterized in that: It includes a core and a cladding layer; The core is nickel-cobalt-manganese hydroxide doped with iridium, the coating layer is nickel-cobalt-manganese hydroxide doped with praseodymium, and the particle size ratio of the core to the iridium-praseodymium doped ternary precursor is 0.6-0.8:1; The chemical formula of the iridium and praseodymium doped ternary precursor is Ni x Co y Mn 1-x-y (OH)2[Ir] m [Pr] n , where 0.34≤x≤0.9, 0.05≤y≤0.33, 0.05≤1-xy≤0.33, 0.0005≤m≤0.007, 0.0005≤n≤0.

007.

2. A method for preparing an iridium-praseodymium doped ternary precursor as claimed in claim 1, characterized in that: include: First, nickel ions, cobalt ions, manganese ions and iridium ions are coprecipitated to obtain the core; Then, nickel ions, cobalt ions, manganese ions and praseodymium ions are co-precipitated on the surface of the inner core to form the coating layer to obtain the iridium and praseodymium doped ternary precursor.

3. The preparation method according to claim 2, characterized in that: include: The first co-precipitation: continuously adding a precipitant, a complexing agent and a first metal salt solution into a first reaction kettle having a base liquid for co-precipitation, stopping the reaction when the particles in the first reaction kettle grow to 60-80% of the target particle size, obtaining a first slurry, and extracting a solid material from the first slurry; Second co-precipitation: adding the solid material, water, precipitant and complexing agent into a second reactor to prepare a bottom slurry, then continuously adding the precipitant, complexing agent and second metal salt solution into the second reactor for co-precipitation until the particles grow to a target particle size and then stopping the reaction to obtain a second slurry, and extracting the iridium and praseodymium doped ternary precursor from the second slurry; The first metal salt solution is a solution in which nickel, cobalt, manganese, or iridium ions are dissolved, or a solution in which nickel, cobalt, and manganese ions are dissolved and a solution in which iridium ions are dissolved; The second metal salt solution is a solution containing nickel, cobalt, manganese and praseodymium ions, or a solution containing nickel, cobalt and manganese ions and a solution containing praseodymium ions.

4. The preparation method according to claim 3, characterized in that: The complexing agent is ammonia water, the pH value of the base liquid is 11.5-12.5, and the ammonia value is 3-16 g / L; during the first coprecipitation process, the pH value in the first reactor is controlled to be 10.8-11.6, and the ammonia value is 3-16 g / L; The pH value of the bottom slurry is 10.8-11.6, and the ammonia value is 3-16 g / L; during the second coprecipitation process, the pH value in the second reactor is controlled to be 10.8-11.6, and the ammonia value is 3-16 g / L.

5. The preparation method according to claim 3, characterized in that: Methods for configuring the base slurry include: The solid material is mixed with water, and then the precipitant and the complexing agent are added to adjust the pH value of the slurry to 10.8-11.6 and the ammonia value to 3-16 g / L to obtain the base slurry with a solid content of 250-350 g / L.

6. The preparation method according to claim 3, characterized in that: Includes at least one of the following features (1) to (5): (1) The first metal salt solution is a solution containing nickel, cobalt, and manganese ions and a solution containing iridium ions; the second metal salt solution is a solution containing nickel, cobalt, and manganese ions and a solution containing praseodymium ions; The concentration of the solution containing nickel, cobalt and manganese ions is 1.8-2.2 mol / L, the concentration of the solution containing iridium ions is 0.1-1 mol / L, and the concentration of the solution containing praseodymium ions is 0.1-1 mol / L; During the first precipitation process, the addition rate of the solution containing nickel, cobalt and manganese ions is 100-800 L / h, and the addition rate of the solution containing iridium ions is 100-600 ml / min; During the second precipitation process, the addition rate of the solution containing nickel, cobalt and manganese ions is 100-800 L / h, and the drop rate of the solution containing praseodymium ions is 100-600 ml / min; (2) The reaction temperature of the first reactor and / or the second reactor is 40-70°C; (3) The method for extracting solid material from the first slurry comprises: The first slurry is subjected to solid-liquid separation, free iridium on the solid material obtained by the solid-liquid separation is washed with pure water, and then dehydrated; (4) The method for extracting the iridium-praseodymium doped ternary precursor from the second slurry comprises: The second slurry is subjected to solid-liquid separation, free praseodymium on the solid material obtained by the solid-liquid separation is washed with pure water, and then dehydrated; (5) The precipitant is a sodium hydroxide solution; the concentration of the sodium hydroxide solution is 5-12 mol / L.

7. A method for preparing a positive electrode material, characterized in that: The method comprises mixing and sintering a lithium source and the ternary precursor as claimed in claim 1 or the ternary precursor prepared by the preparation method as claimed in any one of claims 2 to 6.

8. A positive electrode material, characterized in that The ternary precursor is prepared by using the ternary precursor as claimed in claim 1 or the ternary precursor prepared by the preparation method as claimed in any one of claims 2 to 6 as a raw material.

9. A positive electrode, characterized in that The active material thereof comprises the positive electrode material as claimed in claim 8.

10. A battery, characterized in that: Comprising the positive electrode as claimed in claim 9.

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