Method for producing nickel-rich hydroxide precursor material and method for producing nickel-rich oxide cathode material

Abstract

To provide a method for producing a nickel-rich hydroxide precursor material having a homogeneous structure with an element concentration gradient distribution, using a continuous Taylor vortex flow reactor.SOLUTION: The method for producing a nickel-rich hydroxide precursor material according to the present invention comprises (1) a step of preparing an aqueous solution A in which metal ion raw materials are dissolved, preparing an aqueous solution B in which a manganese source is dissolved, preparing an aqueous solution C in which a precipitating agent is dissolved, preparing an aqueous solution D in which a chelating agent is dissolved, and pouring the aqueous solution A, the aqueous solution C, and the aqueous solution D into a continuous Taylor vortex flow reactor to perform a first coprecipitation reaction, (2) a step of pouring the aqueous solution B into the continuous Taylor vortex flow reactor to perform a second coprecipitation reaction, and (3) a step of washing precipitates that have undergone the second coprecipitation reaction, placing the precipitates in an oven for drying, and obtaining the nickel-rich hydroxide precursor material.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention provides a method for producing a nickel-rich hydroxide precursor material and a nickel-rich oxide cathode material, particularly a method for producing a nickel-rich hydroxide precursor material and a nickel-rich oxide cathode material having an element concentration gradient distribution, which are produced by coprecipitation using a continuous Taylor vortex reactor and mixing using a ball mill. [Background technology]

[0002] As consumer energy demands, such as for hybrid vehicles, smart grids, and power plants, rapidly increase, lithium-ion batteries (LIBs) are being widely investigated as a promising energy storage technology and, more specifically, as one of the optimal energy storage technologies to address energy challenges. While LIBs are the battery of choice for many consumer electronic devices, the oxide cathodes they employ face challenges, including potentially poor mechanical properties and the need for high discharge capacity and long cycle life. Consequently, research into next-generation oxide cathode materials is ongoing. Research primarily focuses on improving the mechanical strength of the materials during the charge / discharge process of LIBs, as well as improving the cycle life, discharge capacity, and safety of the batteries.

[0003] Nickel-rich layered oxide cathodes, with a theoretical discharge capacity of 275 mAh / g and a high operating voltage of 2.8 to 4.3 V, are expected to be a promising cathode material to meet the demands arising from technological developments. Compared to the currently widely used lithium cobalt oxide cathode material (LiCoO2), these nickel-rich oxide cathodes are attracting attention due to their low toxicity and low cost. However, excessive nickel concentration can accelerate the deterioration of the battery's discharge capacity and can cause structural and chemical instability, especially at high temperatures and high operating voltages, posing a significant safety risk. When nickel-rich oxide cathodes are charged at high voltages, unstable Ni atoms form on their surface. 4+As ions are generated, NiO-containing impurity phases are formed and oxygen-containing substances are released. 4+ The ions can accelerate the decomposition of the electrolyte, which can consume the electrolyte and degrade the battery's cycle performance. Furthermore, the electrochemically inactive NiO-containing impurity phase increases the diffusion resistance of lithium ions, slowing the charge / discharge rate. At the same time, the reaction between the O2 released from the oxide and the organic electrolyte can cause thermal runaway in the battery.

[0004] Cation mixing is the process of Li + ions (ionic radius is approximately 0.76 Å) and Ni 2+ This process involves the exchange of positions between ions (with an ionic radius of approximately 0.69 Å) in each layer, and is the primary cause of the deterioration of discharge capacity and the structural phase transition of nickel-rich oxide cathodes. This ion exchange is achieved through similar ionic radii. Furthermore, side reactions occurring when nickel-rich oxides come into contact with air or moisture can produce unwanted residues (e.g., LiOH and Li2CO3) on the surface. These residues interact with the electrolyte to form an insulating surface layer, causing overvoltage during charging of lithium-ion batteries. For these reasons, applying conventional nickel-rich oxides to commercial batteries, such as those used in electric vehicles and smart grids, remains challenging.

[0005] Methods for improving the structural stability of nickel-rich oxide cathodes and the long-term cycle life of batteries include changing the components, adjusting the manufacturing conditions, and surface modification. In particular, in a concentration gradient structure, also known as a core-shell structure, the electrochemically active transition metal (TM) is mainly confined to the core of the active material particles, and an inactive transition metal is used as the shell, which improves the structural stability of nickel-rich oxide cathodes and the cycle performance of lithium-ion batteries. In the prior art, a nickel-rich oxide cathode with a high manganese content, Li[Ni 0.8 Co 0.2 ] x [Ni 0.2 Mn 0.8 ]1-x It has been demonstrated that the use of (1>x>0.5) oxides can minimize surface side reactions. The manganese element in such materials has an average oxidation state of +4, which provides excellent structural stability and allows the material to maintain its hexagonal shape during cycling, even under high voltages. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] JY Liao, A. Manthiram, Surface-modified concentration-gradient Ni-rich layered oxide cathodes for high-energy lithium-ion batteries, Journal of Power Sources 282 (2015) 429-436. Summary of the Invention [Problem to be solved by the invention]

[0007] However, there has yet to be any invention related to a nickel-rich oxide positive electrode material that has long-term cycle stability and can effectively suppress the occurrence of side reactions. [Means for solving the problem]

[0008] Therefore, the present invention provides a method for producing a nickel-rich hydroxide precursor material and a method for producing a quaternary oxide cathode material with an element concentration gradient distribution synthesized from the nickel-rich hydroxide precursor material. In the present invention, nickel-rich (Ni-rich) is defined as a nickel content exceeding 50% by mole in the entire compound. The nickel-rich hydroxide precursor material of the present invention is a nickel-cobalt-manganese hydroxide with a homogeneous structure. That is, unlike prior art techniques that synthesize materials with different core and shell compositions, such as a core-shell structure in which the core is a binary material and the shell is a ternary material, the nickel-rich hydroxide precursor material of the present invention has an inner layer and an outer layer with the same elemental composition, each containing nickel, cobalt, and manganese, with the only difference being the concentration ratios in each layer.

[0009] The nickel-rich hydroxide precursor produced by the method of the present invention has a homogeneous elemental distribution structure with a nickel-rich inner layer and a manganese-rich outer layer, which reduces the interfacial resistance during lithium ion migration, increases the migration paths, and ultimately improves the electrochemical performance and cycle stability of the produced electrode. Furthermore, the nickel-rich oxide positive electrode material produced by the method of the present invention also has a homogeneous structure with an elemental concentration gradient distribution and contains aluminum as an element to stabilize the structure, which can improve the electrochemical performance, such as the charge / discharge rate, of lithium ion batteries, and the mechanical strength of the positive electrode material.

[0010] The method for producing a nickel-rich hydroxide precursor material according to the present invention includes the steps of: pouring aqueous solution A containing nickel ions and cobalt ions, a precipitant (aqueous solution C), and a chelating agent (aqueous solution D) into a continuous Taylor-Flow Reactor (TFR) to carry out a first coprecipitation reaction; further adding aqueous solution B containing manganese ions to carry out a second coprecipitation reaction; and washing and drying the precipitate to obtain a nickel-cobalt-manganese hydroxide precursor.

[0011] The method for producing a nickel-rich oxide cathode material according to the present invention includes the steps of: mixing an ethanol solution containing aluminum ions with the nickel-cobalt-manganese hydroxide precursor, followed by drying; pulverizing and mixing the dried mixture with a lithium source in a ball mill; and performing a three-stage calcination heat treatment to obtain a lithium-nickel-cobalt-manganese-aluminum oxide cathode material.

[0012] Specifically, the present invention provides a method for producing a nickel-rich hydroxide precursor material, which is a nickel-cobalt-manganese hydroxide having a homogeneous structure with an element concentration gradient distribution. The method for producing the nickel-rich hydroxide precursor material includes the following steps: (1) Prepare an aqueous solution A in which a metal ion raw material is dissolved, preparing an aqueous solution B in which a manganese source is dissolved; Prepare an aqueous solution C in which a precipitant is dissolved. An aqueous solution D containing a chelating agent is prepared. A step of pouring the aqueous solution A, the aqueous solution C, and the aqueous solution D into a continuous Taylor vortex reactor and carrying out a first coprecipitation reaction for 2 to 7 hours, the metal ion source is a nickel source and a cobalt source; the nickel source is at least one selected from the group consisting of nickel sulfate, nickel oxalate, nickel acetate, nickel nitrate, nickel chloride, and nickel hydroxide; the cobalt source is at least one selected from the group consisting of cobalt sulfate, cobalt oxalate, cobalt carbonate, cobalt acetate, cobalt nitrate, cobalt chloride, and cobalt hydroxide; the manganese source is at least one selected from the group consisting of manganese sulfate, manganese oxalate, manganese carbonate, manganese citrate, manganese acetate, manganese nitrate, manganese phosphate, electrolytic manganese dioxide, and manganese oxide; (2) pouring the aqueous solution B into the continuous Taylor vortex reactor and carrying out a second coprecipitation reaction for 5 to 70 hours, the reaction temperature of the second coprecipitation reaction is 30°C to 80°C, the pH value of the reaction environment is 9.5 to 12.5, and the rotation speed of the inner cylinder of the continuous Taylor vortex reactor is 200 rpm to 1500 rpm; (3) washing the precipitate that has undergone the second coprecipitation reaction and drying it in an oven to obtain the nickel-rich hydroxide precursor material.

[0013] Furthermore, the concentration of the aqueous solution A is 1.6M to 1.92M.

[0014] Furthermore, the concentration of the aqueous solution B is 0.08M to 0.4M.

[0015] Furthermore, the concentration of the aqueous solution C is 2.0 M to 6.0 M, and the weight molar concentration ratio of the aqueous solution A to the aqueous solution C is 1:1 to 1:5.

[0016] Furthermore, the concentration of the aqueous solution D is 2.5 M to 9.0 M, and the weight molar concentration ratio of the aqueous solution A to the aqueous solution D is 1:1 to 1:5.

[0017] Furthermore, the drying temperature in the oven is 60°C to 120°C, and the drying time is 6 to 24 hours.

[0018] Furthermore, the supply rates of the aqueous solutions A and B are 1.0 to 3.0 ml / min.

[0019] The present invention further provides a method for producing a nickel-rich oxide positive electrode material using the method for producing the nickel-rich hydroxide precursor material, wherein the nickel-rich oxide positive electrode material has a homogeneous structure with an element concentration gradient distribution, and the method for producing the nickel-rich oxide positive electrode material includes the steps of: (a) dispersing an aluminum source in ethanol, adding and mixing the nickel-rich hydroxide precursor material to obtain a mixture, and heating the mixture at a temperature of 80°C until it is completely dried to obtain a mixture a; the aluminum source is at least one selected from the group consisting of aluminum hydroxide, aluminum oxalate, aluminum carbonate, aluminum sulfate, aluminum acetate, aluminum nitrate, and aluminum phosphate; (b) a step of grinding and mixing a lithium source and the mixture a in the step (a) in a molar ratio of 1:1.01 to 1:1.25 to obtain a mixture b, the lithium source is at least one selected from the group consisting of lithium hydroxide, lithium nitrate, lithium acetate, lithium chloride, lithium hydrogen phosphate, lithium phosphate, and lithium carbonate; (c) subjecting the mixture b in step (b) to a three-stage calcination heat treatment to obtain the nickel-rich oxide positive electrode material.

[0020] Furthermore, the conditions for the pulverization are that the ball mill rotation speed is 50 to 200 rpm and the pulverization time is 2 to 10 hours.

[0021] Furthermore, the temperatures and times of the three-stage calcination heat treatment are, respectively, 100°C to 200°C for the first stage and 1 to 3 hours for the second stage, 500°C to 600°C for the second stage and 700°C to 800°C for the third stage, and 10 to 40 hours for the third stage. The temperature rise rate of the three-stage calcination heat treatment is 0.1 to 20°C / min. [Effects of the Invention]

[0022] The nickel-rich oxide cathode material having a homogeneous structure with an element concentration gradient distribution produced by the method of the present invention has a nickel-rich inner layer, a manganese-rich outer layer, and an aluminum-containing surface layer, each of which has an element concentration gradient distribution. This particle structure contributes to the mechanical stability of the cathode material at high charge / discharge rates and can effectively suppress the occurrence of side reactions between the cathode material and the electrolyte.

[0023] Therefore, compared with conventional oxide cathode materials having a uniform concentration, lithium-ion batteries constructed with nickel-rich oxide cathode materials produced using a continuous Taylor vortex reactor have superior electrochemical performance, such as high charge / discharge rates and high discharge capacity retention over long charge / discharge cycles.

[0024] In addition, the nickel-rich hydroxide precursor produced by the coprecipitation reaction using a continuous Taylor vortex reactor in the method of the present invention has uniform, cohesive particles with large particle sizes. Furthermore, because it has needle-shaped primary particles, the regularly arranged secondary particles formed from them have a structure that can withstand tensile and compressive stresses generated by long-term charge and discharge, preventing the occurrence of microcracks and improving manufacturing efficiency in large-scale production.

[0025] Therefore, the present invention provides a method for preparing a nickel-rich hydroxide precursor and a nickel-rich oxide cathode material having a homogeneous structure with an element concentration gradient distribution, which are suitable for large-scale production, and the nickel-rich hydroxide precursor has a homogeneous and stress-resistant structure, and the nickel-rich oxide cathode material has excellent charge-discharge efficiency and long-term cycle stability, thereby significantly improving the electrochemical performance of lithium-ion batteries. [Brief explanation of the drawings]

[0026] [Figure 1] Schematic diagram of the synthesis of nickel-rich hydroxide precursors with a concentration gradient using a continuous Taylor vortex reactor. [Figure 2] 1A is a flow diagram of a method for producing a nickel-rich hydroxide precursor according to one embodiment of the present invention; FIG. 1B is a flow diagram of a method for producing a nickel-rich oxide according to one embodiment of the present invention; [Figure 3] Comparison of XRD diffraction patterns between a CG-NCM precursor with a gradient element concentration and a UC-NCMA precursor with a uniform concentration, both synthesized and produced using TFR. [Figure 4]Comparison of particle size distributions between a CG-NCM precursor with an elemental concentration gradient and a UC-NCMA precursor with a uniform concentration, both produced using TFR. [Figure 5] (a1)~(a4) SEM images at different magnifications of the morphology of the UC-NCMA precursor with uniform concentration produced using TFR, and (b1)~(b4) SEM images at different magnifications of the CG-NCM precursor with element concentration gradient produced using TFR. [Figure 6] (a) High-magnification SEM image of the CG-NCM precursor, (b) low-magnification SEM image of the CG-NCM precursor, (c) longitudinal cross section of the CG-NCM precursor cut with an FIB and its EDS line scan profile, (d) XRD diffraction pattern of the synthesized CG-NCM hydroxide precursor sample with a concentration gradient. [Figure 7] (a) High-magnification SEM image of a calcined UC-NCMA particle sample with a uniform concentration, (b) high-magnification SEM image of a CG-NCMA particle sample with a concentration gradient, (c) low-magnification SEM image of a UC-NCMA particle sample with a uniform concentration, (d) low-magnification SEM image of a CG-NCMA particle sample with a concentration gradient, (e) EDS elemental map of the UC-NCMA oxide, (f) EDS elemental map of the CG-NCMA oxide. [Figure 8] (a) Comparison of XRD diffraction patterns of UC-NCMA and CG-NCMA oxide powder samples, (b) XRD diffraction pattern of UC-NCMA oxide powder sample analyzed by the Rietveld method, (c) XRD diffraction pattern of CG-NCMA oxide powder sample analyzed by the Rietveld method. [Figure 9] TEM images, selected area electron diffraction (SAED) patterns, and EDS elemental maps of (a) UC-NCMA and (b) CG-NCMA particle samples. [Figure 10] XPS spectra of each elemental component in the UC-NCMA and CG-NCMA powder samples: (a) Ni 2p, (b) O 1s, (c) Co 2p, (d) Mn 2p, (e) Li 1s, and (f) C 1s. [Figure 11] Comparison of the electrochemical performance of two types of lithium-ion batteries, UC-NCMA / / Li and CG-NCMA / / Li: (a) initial charge-discharge curves at 0.1C and 25°C; (b) comparison of the electrical characteristics of the batteries at low and high rates (0.2C to 10C); (c) comparison of the electrical characteristics of the batteries after 100 cycles at 1C and 25°C; (d) histogram of the capacity retention rate of the batteries at different rates (0.2C to 10C); (e) comparison of the electrical characteristics of the batteries after 200 cycles at 1C and 25°C. [Figure 12] (a) Comparison of discharge curves at rate capabilities (0.2C~10C) of UC-NCMA / / Li batteries, (b) Comparison of discharge curves at rate capabilities (0.2C~10C) of CG-NCMA / / Li batteries. [Figure 13] Comparison of electrochemical properties of NCMA / / Li batteries: (a) Differential capacity-voltage curves (voltage range: 2.8-4.3 V) after three cycles at 0.1 C for a lithium-ion battery composed of a UC-NCMA oxide cathode and (b) a lithium-ion battery composed of a CG-NCMA oxide cathode, and discharge curves after 100 cycles at 1 C / 1 C for a lithium-ion battery composed of a UC-NCMA oxide cathode and (d) a lithium-ion battery composed of a CG-NCMA oxide cathode. [Figure 14] Cyclic voltammograms of (a) UC-NCMA / / Li battery and (b) CG-NCMA / / Li battery (at a rate of 0.1C / 0.1C, cycled three times, voltage range 2.8-4.3V), and electrochemical resistance change graphs of the UC-NCMA / / Li battery and CG-NCMA / / Li battery (at a charge / discharge rate of 1C / 1C) before (c) cycling and after (d) 100 cycles. [Figure 15] (a) In-situ XRD diffraction pattern of UC-NCMA cathode material during charge-discharge cycling. (b) In-situ XRD diffraction pattern of CG-NCMA cathode material during charge-discharge cycling. [Figure 16]In a single charge-discharge cycle, isoplots of the main characteristic peaks in the in-situ XRD diffraction patterns of (a) UC-NCMA cathode material and (b) CG-NCMA cathode material within the range of 10 to 80° are plotted against the time-voltage graph during the charge-discharge process, and the changes in lattice constants calculated from the in-situ XRD diffraction patterns during the charge-discharge cycle ((c) change in the a-axis lattice constant in the (101) crystal plane, (d) change in the c-axis lattice constant in the (003) crystal plane, (e) change in lattice volume). [Figure 17] (a) Comparison of XRD diffraction patterns after 100 cycles at a charge / discharge rate of 1C / 1C between a battery made of UC-NCMA and a battery made of CG-NCMA positive electrode material, (b) comparison of the displacement of the (003) characteristic peak of the electrode after cycling between a battery made of UC-NCMA and a battery made of CG-NCMA positive electrode material, and (c) comparison of SEM images after 100 cycles at a charge / discharge rate of 1C / 1C between a UC-NCMA positive electrode electrode and (d) a CG-NCMA positive electrode electrode. [Figure 18] Comparison of longitudinal cross sections of active material particles of electrodes after 100 cycles at a charge / discharge rate of 1C / 1C: SEM images of the positive electrodes after 100 cycles at a charge / discharge rate of 1C / 1C for (a) (b) UC-NCMA oxide positive electrode active material particles and (c) (d) CG-NCMA oxide positive electrode active material particles, and TEM images of (e) UC-NCMA positive electrode active material particles and (f) CG-NCMA positive electrode active material particles with selected-area electron diffraction patterns corresponding to the marked areas I and II. DETAILED DESCRIPTION OF THE INVENTION

[0027] The methods for producing nickel-rich hydroxide precursor materials and nickel-rich oxide cathode materials according to the present invention are described below by way of exemplary embodiments. It should be noted that the following exemplary embodiments are only for the purpose of illustrating the present invention and are not intended to limit the scope of the present invention.

[0028] [Method of manufacturing nickel-rich hydroxide precursor material] First, a nickel-rich hydroxide precursor with an element concentration gradient was synthesized by coprecipitation using a continuous Taylor vortex reactor (TFR, 1 L, Laminar Co., Korea), as shown in Figure 1.

[0029] As shown in FIG. 2(a), the method for producing a nickel-rich hydroxide precursor according to the present invention includes the following steps. S11: The metal ion raw material is uniformly mixed with deionized water to prepare a metal ion mixed solution (aqueous solution A); S12: Dissolve the manganese source in deionized water to prepare aqueous solution B; S13: Pour the aqueous solution A, the precipitant aqueous solution (aqueous solution C), and the chelating agent aqueous solution (aqueous solution D) into a continuous Taylor vortex reactor filled with deionized water to carry out a first coprecipitation reaction; S14: Pour aqueous solution B into a continuous Taylor vortex reactor to carry out the second coprecipitation reaction; S15: The precipitate from the second co-precipitation reaction is collected, washed with ethanol and deionized water to remove residual ions, and then dried in an oven to obtain a nickel-rich hydroxide precursor.

[0030] Specifically, the methods for preparing each solution are as follows.

[0031] Preparation of metal ion mixed solution (aqueous solution A): A metal ion source is uniformly dissolved and mixed in deionized water to prepare a metal ion mixed solution (aqueous solution A). In one embodiment, the metal ion source is a nickel source and a cobalt source. In one embodiment, the nickel source as the metal ion source is at least one selected from the group consisting of nickel sulfate, nickel oxalate, nickel acetate, nickel nitrate, nickel chloride, and nickel hydroxide. The cobalt source as the metal ion source is at least one selected from the group consisting of cobalt sulfate, cobalt oxalate, cobalt carbonate, cobalt acetate, cobalt nitrate, cobalt chloride, and cobalt hydroxide. In one embodiment, the concentration of aqueous solution A is 1.6 M to 1.92 M, preferably 1.7 M to 1.92 M, more preferably 1.8 M to 1.92 M, and even more preferably 1.92 M.

[0032] Preparation of aqueous solution B: A manganese source is dissolved in deionized water to prepare aqueous solution B. In one embodiment, the manganese source is at least one selected from the group consisting of manganese sulfate, manganese oxalate, manganese carbonate, manganese citrate, manganese acetate, manganese nitrate, manganese phosphate, electrolytic manganese dioxide, and manganese oxide (e.g., α-MnO2, β-MnO2, γ-MnO2, Mn2O3, and Mn3O4). In one embodiment, the concentration of aqueous solution B is 0.08 M to 0.4 M, preferably 0.08 M to 0.2 M, more preferably 0.08 M to 0.1 M, and even more preferably 0.08 M.

[0033] Preparation of precipitant aqueous solution (aqueous solution C): A precipitant is uniformly dissolved and mixed in deionized water to prepare a precipitant aqueous solution for the subsequent coprecipitation reaction. In one embodiment, the precipitant is sodium hydroxide. In one embodiment, the concentration of aqueous solution C is 2.0 M to 6.0 M, preferably 2.5 M to 5.0 M, more preferably 3.0 M to 4.5 M, and even more preferably 4 M. In one embodiment, the weight molar concentration ratio of aqueous solution A to aqueous solution C is 1:1 to 1:5, preferably 1:1 to 1:4, more preferably 1:1 to 1:3, and even more preferably 1:2.

[0034] Preparation of chelating agent aqueous solution (aqueous solution D): A chelating agent is uniformly dissolved and mixed in deionized water to prepare a chelating agent aqueous solution for the subsequent coprecipitation reaction. In one embodiment, the chelating agent is aqueous ammonia. In one embodiment, the concentration of aqueous solution D is 2.5 M to 9.0 M, preferably 4.0 M to 9.0 M, more preferably 6.0 M to 8.0 M, and even more preferably 7.2 M. In one embodiment, the weight molar concentration ratio of aqueous solution A to aqueous solution D is 1:1 to 1:5, preferably 1:1 to 1:4, more preferably 1:1 to 1:3, and even more preferably 1:3.

[0035] In one embodiment, all of the aqueous solutions are pre-filtered to remove unwanted impurities before carrying out the co-precipitation reaction.

[0036] A schematic diagram of producing a nickel-rich hydroxide precursor using a TFR is shown in Figure 1. As the inner cylinder of the TFR rotates, aqueous solutions A, C, and D are poured into the front inlet of the cylindrical chamber of the TFR, which is filled with deionized water. After a first coprecipitation reaction, aqueous solution B is poured into the upper inlet of the TFR, and a second coprecipitation reaction is carried out with a mixed solution of aqueous solutions A, C, and D in the cylindrical chamber of the TFR. In one embodiment, the first coprecipitation reaction lasts for 2 to 7 hours, preferably 3 to 6 hours, and more preferably 5 hours. In one embodiment, the second coprecipitation reaction lasts for 5 to 70 hours, preferably 15 to 55 hours, and more preferably 20 to 30 hours. In one embodiment, the temperature of the second coprecipitation reaction can be 30°C to 80°C, preferably 45°C to 70°C, and more preferably 60°C. Among these, a coprecipitation reaction at 60°C is most complete, producing spherical secondary particles composed of needle-like primary particles, achieving favorable regular arrangement and denseness. The environmental pH value can be 9.5 to 12.5, preferably 10.0 to 12.0, and more preferably 11.2. The reaction can be stably controlled by controlling the flow rate of aqueous solution C. At a pH of 11.2, the coprecipitation reaction reaches a steady state, achieving an optimal particle size distribution. In one embodiment, the rotation speed of the inner cylinder of the TFR can be 200 rpm to 1500 rpm, preferably 400 rpm to 1000 rpm, more preferably 500 rpm to 800 rpm, and even more preferably 600 rpm. A rotation speed of 600 rpm is most preferable for polycrystalline positive electrode materials, as it contributes most to the generation of secondary particles with a particle size of approximately 8 to 12 μm. The supply rates of aqueous solutions A and B are 1.0 ml / min to 3.0 ml / min, preferably 1.5 ml / min to 2.0 ml / min, and more preferably 1.703 ml / min. This allows for continuous production.

[0037] It should be further explained that the present invention uses a TFR to produce hydroxide precursors. Compared to a batch reactor used in a conventional continuous stirred tank reactor (CSTR), TFR production has the following advantages:

[0038] Controllability and uniformity: The TFR can achieve various fluid flow patterns by controlling the rotation speed of the reactor's inner cylinder. In this embodiment, a fluid mixing pattern called Taylor vortex flow, which belongs to micro-scale mixing, can create an environment in which the coprecipitation reaction occurs that is more favorable for producing a more uniform nickel-rich hydroxide precursor. In contrast, conventional batch reactors perform mixing using a flow pattern called turbulent flow, which belongs to macro-scale mixing. This can cause differences or variations in particle size and material composition, which can easily affect material uniformity and production efficiency, especially in large-scale production applications.

[0039] Scalability: Generally, the production of nickel-rich hydroxide precursors can be scaled up from laboratory level to industrial production, meaning the required reactor volume ranges from 1L to 1000L. The TFR's continuous operation and scalability ensure consistent quality in mass production. Meanwhile, traditional batch reactors are suitable for small-scale research and development, and it is difficult to maintain consistent reaction conditions and product quality in mass production.

[0040] Reaction time and production efficiency: In the manufacturing process of nickel-rich hydroxide precursor, the continuous production and microscale mixing characteristics of TFR can effectively shorten the manufacturing time of the material, thereby improving production efficiency. On the other hand, mixing using a conventional batch reactor belongs to macroscale mixing, which requires a longer reaction time, making it less efficient for continuous or large-scale manufacturing processes.

[0041] It should be further explained that the reaction parameters in the TFR, such as the reaction environment temperature, pH value, rotation speed of the inner cylinder, and supply rates of aqueous solutions A and B, have a significant effect on the properties of the produced nickel-rich hydroxide precursor, and therefore it is extremely important to set and control these conditions. (1) Reaction temperature: The temperature in the reaction environment has a significant effect on the shape of the nickel-rich hydroxide precursor particles. If the temperature is too low, the particle formation will be incomplete, and if the temperature is too high, the shape of the formed primary particles may be different from what was expected. (2) Rotational Speed ​​of the Inner Cylinder: The rotational speed of the inner cylinder of the TFR directly affects the particle size of the precursor. Increasing the rotational speed creates smaller vortex flows, resulting in a smaller particle core, which in turn produces a larger amount of small particles. Particles that are too small (particle size < approximately 1-3 μm) result in a larger surface area and higher solid electrolyte interface (SEI) resistance, which can adversely affect the electrochemical performance of the cathode in subsequent cathode material fabrication. On the other hand, particles that are too large (particle size > approximately 20-30 μm) have longer lithium ion migration paths, which slows the lithium ion diffusion rate and reduces the overall electrochemical performance of the cathode material. To achieve optimal electrochemical performance in the cathode material, the particle size of the material produced by the method of the present invention is preferably 8-12 μm. (3) Supply rate and pH value of aqueous solution A and aqueous solution B: If the supply rate is too fast or the pH value is too high, a large amount of hydroxide particle cores will be produced, resulting in incomplete particle formation and a loose structure. Such particles are prone to disintegration and powdering during the subsequent manufacturing process. On the other hand, if the supply rate is too slow, the particles will remain in the reaction chamber for a long time, reducing manufacturing efficiency. Also, if the pH value is too low, it will directly affect the particle shape.

[0042] This allows the mixed solution in the cylindrical chamber of the TFR to react sufficiently under the above conditions. Next, the precipitate from the coprecipitation reaction is collected at the outlet end of the cylindrical chamber, and the remaining Na is removed using ethanol and deionized water. + , SO4 2- The nickel-rich hydroxide precursor Ni is then washed and removed, and placed in an oven for drying. In one embodiment, the oven temperature can be set to 60°C to 120°C, preferably 60°C to 100°C, more preferably 60°C to 80°C, and even more preferably 60°C. The drying time can be set to 6 to 24 hours, preferably 8 to 20 hours, more preferably 10 to 15 hours, and even more preferably 12 hours. After the drying treatment, the nickel-rich hydroxide precursor Ni x Co y Mn 1-x-y (OH)2 is obtained.

[0043] [Method of manufacturing nickel-rich oxide cathode material] As shown in FIG. 2(b), the method for producing a nickel-rich oxide according to the present invention is as follows. S21: Disperse an aluminum source in ethanol, add a nickel-rich hydroxide precursor and mix to obtain a mixture, and heat the mixture until it is completely dry to obtain mixture a; S22: Using a ball mill, the lithium source and the mixture a in S21 are pulverized and mixed with grinding balls to obtain mixture b; S23: Mixture b in S22 is subjected to three-stage calcination heat treatment in a high-temperature furnace.

[0044] An aluminum source is dispersed in an appropriate amount of ethanol, the prepared nickel-rich hydroxide precursor powder is added, and the mixture is thoroughly mixed and heated at a constant temperature until completely dried, to obtain mixture a. In one embodiment, the aluminum source is Al(OH). In one embodiment, the constant temperature is 70°C to 90°C, preferably 80°C.

[0045] Next, a lithium source is added to the mixture a. In one embodiment, the lithium source is a lithium salt, LiOH·HO. In one embodiment, the molar ratio of the mixture a to the lithium source is 1:1.01 to 1:1.25, preferably 1:1.01 to 1:1.20, more preferably 1:1.01 to 1:1.10, and even more preferably 1:1.05.

[0046] Next, the mixture is milled and mixed using a ball mill with PU balls or agate balls to obtain mixture b. The rotation speed of the ball mill is 50 rpm to 200 rpm, preferably 70 rpm to 150 rpm, more preferably 80 rpm to 125 rpm, and even more preferably 100 rpm. The milling time is 2 to 10 hours, preferably 3 to 8 hours, more preferably 4 to 6 hours, and even more preferably 5 hours. The ratio of the PU balls or agate balls to the sample obtained by mixing the mixture and the lithium source is 1:1 to 1:20, preferably 1:1 to 1:10, more preferably 1:1 to 1:5, and even more preferably 1:1.

[0047] Next, mixture b is subjected to a three-stage calcination heat treatment in a high-temperature furnace in an air or pure oxygen atmosphere, with a pure oxygen atmosphere being preferred. The temperature in the first stage of the three-stage calcination heat treatment is 100°C to 200°C, preferably 120°C to 180°C, more preferably 140°C to 160°C, and even more preferably 150°C. The calcination time is 1 to 3 hours, preferably 1.5 to 2.5 hours, and more preferably 2 hours. The temperature in the second stage is 500°C to 600°C, preferably 520°C to 580°C, more preferably 540°C to 560°C, and even more preferably 550°C. The calcination time is 4 to 8 hours, preferably 5 to 7 hours, and more preferably 6 hours. The temperature in the third stage is 700°C to 800°C, preferably 710°C to 775°C, more preferably 720°C to 750°C, and even more preferably 730°C. The calcination time is 10 to 40 hours, preferably 15 to 30 hours, and more preferably 20 hours. The temperature rise rate in each of these three calcination heat treatment stages is 0.1 to 20°C / min, preferably 0.5 to 10°C / min, more preferably 1 to 5°C / min, and even more preferably 2°C / min.

[0048] This results in a nickel-rich oxide cathode material having a homogeneous structure with an element concentration gradient distribution.

[0049] The nickel-rich oxide cathode material prepared in this embodiment has significant differences in its electrochemical performance due to the varying ratios of nickel, cobalt, manganese, and aluminum ions. The higher the nickel content, the higher the discharge capacity of the oxide cathode material. The higher the aluminum or manganese content, the better the structural stability of the material.

[0050] In the following examples, a nickel-rich hydroxide precursor material and a nickel-rich oxide positive electrode material are synthesized by the above-described methods for producing a nickel-rich hydroxide precursor material and a nickel-rich oxide positive electrode material, respectively, and the related material properties are measured and the electrical properties of the battery are evaluated.

[0051] [Example 1] Nickel-rich hydroxide precursor material [Ni 0.91 Co 0.05 Mn 0.04 ](OH)2

[0052] Aqueous solution A was prepared by dissolving 1.82 M NiSO4·6H2O and 0.1 M CoSO4·7H2O in deionized water as metal ion sources. Aqueous solution B was prepared by dissolving 0.08 M MnSO4·H2O in deionized water. Aqueous solution C was prepared by dissolving sodium hydroxide as a precipitant in deionized water to prepare a 4 M solution. Aqueous solution D was prepared by dissolving aqueous ammonia in deionized water as a chelating agent to prepare a 7.2 M solution. All of the solutions were filtered to remove impurities before the coprecipitation reaction. The weight molar concentration ratio of Aqueous Solution A to Aqueous Solution C was 1:2, and the weight molar concentration ratio of Aqueous Solution A to Aqueous Solution D was 1:3.

[0053] Aqueous solutions A, C, and D were poured into a continuous Taylor vortex reactor and the first coprecipitation reaction was carried out for 5 hours. Then, aqueous solution B was poured into the reactor and the second coprecipitation reaction with aqueous solution A was carried out for 25 hours. The second coprecipitation reaction was carried out at a reaction temperature of 60°C, a pH of 11.2, and a stable reaction was achieved by controlling the NaOH flow rate. The continuous Taylor vortex reactor was operated at an inner cylinder rotation speed of 600 rpm and a feed rate of 1.703 ml / min for aqueous solutions A and B. The precipitate from the second coprecipitation reaction was collected at the outlet end of the cylindrical chamber, washed multiple times with ethanol and deionized water to remove residual ions, and then dried in an oven at 60°C for 12 hours. This resulted in the formation of a [Ni] solution with an elemental concentration gradient. 0.91 Co 0.05 Mn 0.04 ](OH) hydroxide precursor was obtained, which is referred to as CG-NCM precursor in this example.

[0054] [Example 2] Nickel-rich oxide cathode material Li[Ni 0.90 Co 0.04 Mn 0.03 Al 0.03 ]O2

[0055] 0.15 g of Al(OH)3 was dispersed in 20 ml of ethanol, and 5 g of CG-NCM precursor powder was added and thoroughly mixed to form a mixture. The mixture was then heated to 80 °C until completely dry, yielding mixture a. Next, LiOH·H2O and mixture a were milled and mixed in a ball mill at a molar ratio of 1:1.05 at 100 rpm for 5 hours to obtain mixture b. In this example, the milling and mixing was performed using PU balls or agate balls (sample to ball ratio: 1:1). Finally, mixture b was subjected to a three-stage calcination heat treatment in a pure oxygen atmosphere. The first stage was at 150 °C for 2 hours, the second stage was at 550 °C for 6 hours, and the third stage was at 730 °C for 20 hours. The heating rate for all three stages was set at 2 °C / min. This resulted in the formation of Li[Ni]O, which has a homogeneous structure with element concentration gradient distribution. 0.90 Co0.04 Mn 0.03 Al 0.03 ]O2 oxide cathode material was obtained, which is referred to as CG-NCMA oxide in this example.

[0056] To compare the effects of two oxide cathode materials with different concentration distributions, a nickel-rich hydroxide precursor material with a uniform concentration distribution was prepared using the same manufacturing method and parameters. Specifically, the metal ion sources of nickel, cobalt, manganese, and aluminum were all dissolved in a single solution, which was then directly poured into a TFR for coprecipitation reaction, resulting in a nickel hydroxide precursor with a uniform concentration. 0.90 Co 0.04 Mn 0.03 Al 0.03 The (OH)2 precursor was prepared and finally subjected to calcination heat treatment under the same conditions as above. This resulted in the formation of Li[Ni 0.90 Co 0.04 Mn 0.03 Al 0.03 ]O2 oxide cathode material was obtained, which is referred to here as UC-NCMA oxide.

[0057] [Comparative Example 1] A hydroxide precursor with a uniform concentration distribution was prepared using TFR in the same manner as in Example 1. Metal ion sources of nickel, cobalt, manganese, and aluminum were dissolved in a single solution and then directly poured into TFR to carry out coprecipitation. This resulted in a hydroxide precursor with a uniform concentration of [Ni 0.90 Co 0.04 Mn 0.03 Al 0.03 ](OH)2 hydroxide precursor was obtained, which is designated as UC-NCMA precursor.

[0058] Comparative Example 2 The dried UC-NCMA precursor powder was subjected to a calcination heat treatment under the same conditions as in Example 2. This resulted in a Li[Ni 0.90 Co 0.04 Mn 0.03 Al 0.03]O2 oxide sample was obtained, which is designated as UC-NCMA oxide.

[0059] Below, examples of the present invention and comparative examples will be compared based on the analysis and measurement of each material.

[0060] [Crystal plane intensity ratio analysis] The crystal plane intensity ratios of the two hydroxide precursors, CG-NCM and UC-NCMA, were analyzed using an X-ray diffractometer (XRD). As shown in Figure 3, the preferred crystal orientation of the UC-NCMA precursor prepared using TFR was the (001) crystal plane (2θ = 19.2°), while the preferred crystal orientation of the CG-NCM precursor prepared using TFR in the present invention was the (101) crystal plane (2θ = 38.6°). Therefore, the intensity ratio (I) of the (101) crystal plane to the (001) crystal plane of the CG-NCM precursor prepared using TFR was (101) / I (001) ) is 1.45, and the I of the UC-NCMA precursor prepared by TFR (101) / I (001) = 0.82.

[0061] [Particle size analysis] Dynamic light scattering (DLS) was used to analyze the particle size of the two hydroxide precursors, CG-NCM and UC-NCMA, prepared by TFR. As shown in Figure 4, the particle size distribution of the UC-NCMA precursor had two peaks at 0.24 μm and 6.76 μm, respectively, while the particle size distribution of the CG-NCM precursor had two peaks at 0.26 μm and 8.15 μm, respectively. This indicates that the particles of the CG-NCM precursor were relatively larger and more uniformly aggregated.

[0062] [Surface morphology analysis] The surface morphology of the two hydroxide precursors, CG-NCM and UC-NCMA, prepared by TFR was observed using a scanning electron microscope (SEM). Figures 5(a1)–5(a4) show SEM images of the UC-NCMA precursor at different magnifications. Figures 5(b1)–5(b4) show SEM images of the CG-NCM precursor at different magnifications. As shown in Figures 5(a3) and 5(a4), the primary particles of the UC-NCMA precursor with a uniform concentration had a granular distribution, which led to the formation of secondary particles, as shown in Figures 5(a1) and 5(a2). Furthermore, the primary particles of the CG-NCM precursor had a needle-like shape, as shown in Figures 5(b3) and 5(b4), which led to the formation of secondary particles, as shown in Figures 5(b1) and 5(b2). The one-dimensional structure of the needle-like primary particles of the CG-NCM precursor can resist microcracks caused by tensile and compressive stresses due to expansion and contraction resulting from the long-term charge-discharge process.

[0063] From the above, the method of the present invention for producing CG-NCM hydroxide precursor using TFR not only improves the continuity and efficiency of large-scale production, but also produces nickel-rich hydroxide precursor particles with uniform and concentrated particle size, and a special one-dimensional acicular primary particle morphology.

[0064] [Observation of distribution of metal elements in nickel-rich oxides] [Analysis equipment and methods] Diffraction patterns of the CG-NCM precursor and CG-NCMA oxide powders were obtained using a Bruker D2 PHASER (Cu Kα5, λ = 0.1534753 nm, 30 kV; Germany). Quantitative analysis was performed using the Rietveld refinement method with the software TOPAS (v.4.0). The microstructure, surface morphology, and longitudinal cross-section of the prepared powder samples were observed using a scanning electron microscope (SEM; JOEL, JSM-IT200 InTouch Scope™, 15 kV; Japan), followed by energy-dispersive X-ray spectroscopy (EDS). To elucidate the elemental distribution within the particle structure of the CG-NCM precursor and CG-NCMA oxide powders, cross-section analysis of the particle samples was performed using a focused ion beam (FIB; FEI Helios G4 UX). A high-resolution transmission electron microscope (HR-TEM; JEOL JEM-2100F; Japan) was used to characterize the microstructure of the crystals. An X-ray photoelectron spectroscopy (XPS; PHI5600, PerkinElmer; USA) was used to analyze the oxidation states of transition metal elements, C, and O atoms. Data fitting and analysis were performed using an Al Kα (1486.6 eV) excitation source and XPSPEAK 4.1.

[0065] [FIB / SEM EDS scanning analysis] The CG-NCM precursor of Example 1 of the present invention was produced in a TFR at an ideal rotation speed (600 rpm) and pH value (11.2). The resulting microspherical particle structure exhibited a concentrated particle size distribution and excellent sphericity. Furthermore, by thoroughly mixing the resulting CG-NCM precursor with a manganese concentration gradient and an aluminum source and performing a calcination heat treatment under ideal conditions, a CG-NCMA oxide cathode material containing a large amount of manganese in the outer layer and aluminum in the surface layer was obtained. Figures 6(a) and 6(b) are high- and low-magnification SEM images, respectively, of the CG-NCM precursor produced using the method of the present invention. The high-magnification SEM image showed the nano-level acicular morphology of the primary particles, while the low-magnification SEM image showed the spherical secondary particles (diameter approximately 8–12 μm). Furthermore, the CG-NCM precursor particles were cut using FIB, and the distribution of metal elements on the cut surface was analyzed by line scanning. Figure 6(c) shows the distribution of each element along the longitudinal cross section (arrow) of the CG-NCM precursor. The nickel concentration in the inner layer is higher than that in the outer layers near the left and right sides, and the manganese concentration exhibits a concentration gradient distribution that gradually increases from the inner layer to the outer layer. Figure 6(d) also reveals that the XRD diffraction pattern of the CG-NCM precursor has no extraneous impurity phases and a clear characteristic peak. In other words, although the outer layer of the particle contains a large amount of manganese, because the manganese cations are already integrated into the CG-NCM precursor structure, the CG-NCM precursor does not consist of a single manganese hydroxide crystalline phase, but rather has a homogeneous structure with a gradient element concentration distribution from the inner layer to the outer layer.

[0066] As shown in Figures 7(a) to 7(d), the spherical morphology of the secondary particles of UC-NCMA oxide and CG-NCMA oxide was maintained after calcination. Furthermore, the primary particles of CG-NCMA oxide, which had a nano-level needle-like morphology, formed a rod-like particle distribution with excellent crystallinity. Furthermore, the EDS elemental maps in Figures 7(e) and 7(f) revealed that the surface of a single spherical secondary particle was composed of four elements: nickel, cobalt, manganese, and aluminum, and all metal element components were uniformly distributed.

[0067] [Analysis of XRD diffraction patterns using the Rietveld method] Figure 8(a) shows a comparison of the XRD diffraction patterns of powder samples of UC-NCMA oxide and CG-NCMA oxide prepared using the method of the present invention. It can be seen that all diffraction peaks accurately correspond to the hexagonal α-NaFeO2 structure of the R-3m space group, which has high crystallinity. Furthermore, the (006) / (012) and (018) / (110) characteristic peaks were found to be significantly split, indicating that the analyzed materials are crystalline with a regular structure. Furthermore, the (003) / (104) peak ratio R of the UC-NCMA oxide prepared by the method of the present invention is 1.68, while the (003) / (104) peak ratio R of the CG-NCMA oxide is 1.55, both of which are significantly greater than 1.2. Therefore, the UC-NCMA oxide and CG-NCMA oxide powder samples were prepared under conditions of minimal cation mixing, suggesting that these NCMA-based cathode materials have excellent crystalline structures. Next, as shown in Figure 8(b) and Figure 8(c), the Rietveld refinement was performed on the XRD diffraction patterns, and the lattice constants of the two powder samples were compared with the refinement results. The relevant data are shown in Table 1.

[0068] [Table 1]

[0069] [TEM image analysis] As shown in Figures 9(a) and 9(b), TEM images were used to observe the microstructures of the UC-NCMA oxide and CG-NCMA oxide samples, respectively. The primary particle samples of UC-NCMA oxide and CG-NCMA oxide prepared by the method of the present invention possess a distinct layered crystalline structure. Using microscope image analysis software, the lattice fringes of the two primary particle samples were aligned with the hexagonal (003) crystal plane, revealing that the interplanar spacing was approximately 0.47 nm. Selected area electron diffraction (SAED) patterns also demonstrated excellent crystallinity and a perfect layered structure. TEM-EDS analysis (Figure 9(b)) showed the concentration gradient distribution of the CG-NCMA oxide primary particle sample. The analysis results indicated that all metal elements were uniformly distributed throughout the primary particles, with manganese and aluminum concentrations significantly higher than nickel concentrations on the particle surface, consistent with the FIB / SEM EDS line scan results. When the surface of the particles at the grain boundaries has a relatively high concentration of manganese and aluminum elements, it is possible to reduce side reactions between the positive electrode material and the surrounding electrolyte and improve the structural stability of the positive electrode material, thereby improving the charge-discharge cycle performance of the lithium-ion battery.

[0070] [XPS Spectral Measurement and Analysis] To analyze the elemental composition and valence of the transition metals, samples of CG-NCMA oxide and UC-NCMA oxide were measured using an X-ray photoelectron spectrometer. As shown in Figure 10(a), the Ni 2p spectrum showed two distinct peaks at approximately 855 eV (Ni 2p3 / 2) and approximately 872 eV (Ni 2p1 / 2), along with two satellite peaks. The peak near 855 eV was due to Ni coexisting on the surface of the cathode material. 3+ and Ni 2+ The peaks of Ni, which can easily move from the TM layer to the lithium layer, are overlapped and fitted. 2+ The ion is Li +Occupation of ionic sites can lead to permanent site exchange (cation mixing), resulting in battery capacity degradation.

[0071] From the results of the semi-quantitative analysis and Figure 10(a), it is clear that Ni in the CG-NCMA oxide 2+ The ratio of Mn ions was found to be significantly lower than that of the UC-NCMA oxide (CG-NCMA: 6%, UC-NCMA: 46%). 4+ The concentration gradient distribution of ions is Ni in the surface region of the cathode material. 3+ Ni 2+ This can reduce the amount of Ni ions in the surface region, thereby changing the valence of Ni ions. 3+ The cation ratio is such that after high-temperature calcination, such materials will have a high oxidation number, which can effectively reduce cation mixing.

[0072] Figure 10(b) shows the O 1s spectrum, which is a graph fitting the characteristic peaks of the O element in the lattice and surface. The characteristic peaks are located at approximately 529 eV and 532 eV, respectively. The low intensity of the C=O oxygen signal in the CG-NCMA oxide indicates that the amount of Li2CO3 residue on the surface is small. Figures 10(c) and 10(d) show XPS spectra fitting the Co 2p and Mn 2p, respectively. The valence of cobalt is +3 (Co 3+ ), and the valence of manganese is +4 (Mn 4+ ) Figures 10(c) and 10(d) show that the Co 2p signal intensity of the CG-NCMA oxide is lower and the Mn 2p signal intensity is higher than that of the UC-NCMA oxide. This means that the surface region of the CG-NCMA oxide has a higher concentration of manganese element.

[0073] The XPS spectra of Li 1s in Fig. 10(e) and C 1s in Fig. 10(f) reveal that the signal intensities of Li and C=O carbon atoms on the surface of CG-NCMA oxide are weaker than those of UC-NCMA oxide, which means that the amount of impurities containing lithium components (e.g., Li2CO3 and LiOH) on the surface of CG-NCMA oxide is smaller.

[0074] [Electrochemical measurements] NCMA-based positive electrodes (including UC-NCMA oxide positive electrodes and CG-NCMA oxide positive electrodes) were constructed by coating the electrode paste onto aluminum foil. The electrode paste formulation included 80% NCMA-based active material, 10% conductive carbon black (Super P®), 10% polyvinylidene fluoride (PVDF) adhesive, and N-methylpyrrolidone (NMP) as a solvent. The positive electrodes were then dried in a vacuum oven at 120°C for 12 hours and pressed into 13 mm diameter disc-shaped electrodes (mass loading: 2.5 mg / cm). 2 The lithium metal foil was used as the negative electrode, and the electrolyte was a 1M LiPF6 solution containing ethylene carbonate (EC) and diethyl carbonate (DEC) in a 1:1 volume ratio. The battery was then assembled into a CR-2032 button cell.

[0075] All electrochemical measurements in this invention were performed using a BCS-805 workstation (BioLogic, France) to carry out charge-discharge tests. The lithium-ion batteries fabricated by the above method were subjected to a charge-discharge test at 2.8 to 4.3 V (Li / Li +Constant-current charge-discharge tests were performed within a voltage range (relative to the voltage of the battery). Cycle life tests were performed at a charge-discharge rate of 1 C / 1 C (1 C = 200 mA / g) for 100 and 200 charge-discharge cycles. Rate capability tests were performed at low and high current rates of 0.2 C to 10 C. Cyclic voltammetry experiments were performed at a voltage range of 2.5 to 4.3 V with a sweep rate of 0.01 mV / s. Electrochemical impedance spectroscopy (EIS) analysis was performed using a MetrOhm AutoLab® system with a frequency range of 100 kHz to 0.01 Hz and an AC amplitude of 5 mV.

[0076] Figure 11(a) shows the initial charge-discharge curves for the UC-NCMA and CG-NCMA cathodes in an NCMA / / Li half cell tested at a voltage range of 2.8 to 4.3 V and a charge-discharge rate of 0.1 C. The initial discharge capacity of the UC-NCMA oxide cathode was approximately 213 mAh / g, while that of the CG-NCMA oxide cathode was approximately 209 mAh / g, slightly lower than that of the UC-NCMA oxide cathode. This is due to the relatively low content of nickel in the outer layer, which has a concentration gradient distribution in the CG-NCMA oxide, and the presence of aluminum in the surface layer.

[0077] As shown in Figures 11(b) and 11(d), the rate performance of the two cathodes was measured at low and high discharge rates of 0.2, 0.5, 1, 3, 5, and 10 C under a maximum voltage of 4.3 V. The results showed that the discharge capacity of the CG-NCMA oxide cathode was higher than that of the UC-NCMA oxide cathode. At high discharge rates of 5 C and 10 C, the discharge capacities of the CG-NCMA oxide cathode were 168.7 and 159.5 mAh / g, respectively, while those of the UC-NCMA oxide cathode were only 146.8 and 127.7 mAh / g, respectively. The low and high discharge curves of the two cathodes are shown in Figure 12. Furthermore, Figure 11(d) shows that at a high discharge rate of 10 C, the CG-NCMA oxide cathode had a capacity retention rate of approximately 83% of the 0.2 C discharge capacity (100%), while the UC-NCMA oxide cathode had a capacity retention rate of only approximately 67%.

[0078] These results suggest that the use of CG-NCMA oxide cathodes can improve the electrochemical performance of lithium-ion batteries. This is due to their perfect and stable crystalline structure and their resistance to distortion during charge-discharge processes. In contrast, UC-NCMA oxide cathodes are prone to degradation of discharge capacity at high discharge rates. This is likely due to microcracks already present in the cathode material and a phase transition occurring in the oxide structure.

[0079] Figure 11(c) compares the electrochemical performance of the UC-NCMA and CG-NCMA oxide cathodes after 100 charge-discharge cycles at a charge-discharge rate of 1 C / 1 C, a cutoff voltage of 2.8–4.3 V, and an ambient temperature of 25°C. The results show that the CG-NCMA oxide cathode retains 91.5% of its initial discharge capacity and exhibits excellent cycle stability, while the UC-NCMA oxide cathode retains only 83.4% of its initial discharge capacity. Furthermore, as shown in Figure 11(e), after 200 charge-discharge cycles under the same conditions, the CG-NCMA oxide cathode retains 80.2% of its initial discharge capacity, while the UC-NCMA oxide cathode retains only 64.1% of its initial discharge capacity.

[0080] Table 2 compares the electrochemical performance of NCMA / / Li batteries constructed with the cathode material having the elemental concentration gradient produced by the method of the present invention with several prior art lithium-ion batteries. Table 2 reveals that the CG-NCMA oxide cathode of the present invention has excellent cycle stability. This is because the CG-NCMA oxide has a relatively high concentration of manganese in the outer layer and aluminum in the surface layer, resulting in excellent material structural stability. Furthermore, this elemental concentration gradient distribution effectively suppresses side reactions caused by contact between the cathode and the electrolyte during long-term cycling.

[0081] [Table 2]

[0082] Prior art documents in Table 2: 1. Y. Zhang, H. Li, J. Liu, J. Zhang, F. Cheng, J. Chen, LiNi 0.90 Co 0.07 Mg 0.03 O2 cathode materials with Mg-concentration gradient for rechargeable lithium-ion batteries, Journal of Materials Chemistry A 7 (36) (2019) 20958-20964. 2. C.-L. Xu, W. Xiang, Z.-G. Wu, Y.-D. Xu, Y.-C. Li, M.-Z. Chen, G. Xiao Dong, G.-P. Lv, J. Zhang, B.-H. Zhong, Constructing a Protective Pillaring Layer by Incorporating Gradient Mn 4+ to Stabilize the Surface / Interfacial Structure of LiNi 0.815 Co 0.15 Al 0.035 O2 Cathode, ACS Applied Materials & Interfaces 10 (33) (2018) 27821-27830. 3. U.-H. Kim, S.-T. Myung, C. S. Yoon, Y.-K. Sun, Extending the Battery Life Using an Al- Doped Li[Ni 0.76 Co 0.09 Mn 0.15 O2 Cathode with Concentration Gradients for Lithium Ion Batteries, ACS Energy Letters 2 (8) (2017) 1848-1854. 4. P. Hou, F. Li, Y. Sun, H. Li, X. Xu, T. Zhai, Multishell Precursors Facilitated Synthesis of Concentration-Gradient Nickel-Rich Cathodes for Long-Life and High-Rate Lithium- Ion Batteries, ACS Applied Materials and Interfaces 10 (29) (2018) 24508-24515. 5. K. Du, C. Hua, C. Tan, Z. Peng, Y. Cao, G. Hu, A high-powered concentration-gradient Li(Ni 0.85 Co 0.12 Mn 0.03 )O2cathode material for lithium ion batteries, Journal of Power Sources 263 (2014) 203-208.

[0083] Figures 13(a) and 13(b) show differential capacity analysis (DCA) curves (dQ / dV vs. V) after three cycles at a charge-discharge rate of 0.1C. In these figures, the polarization phenomena during subsequent cycles caused the negative and positive peaks to shift, respectively, resulting in three typical interconversions between the hexagonal and monoclinic phases. The curves for the three cycles shown in Figures 13(a) and 13(b) overlap well, indicating that both the UC-NCMA and CG-NCMA oxide cathodes exhibit high stability and electrochemical reversibility at low charge-discharge rates.

[0084] However, as shown in Figure 13(c), the UC-NCMA oxide cathode showed significant polarization after 100 charge-discharge cycles at a 1C charge-discharge rate. The positive electrode peak near 4.2 V is a criterion for determining the reversibility of the H⇔H⇔ phase transition. In contrast, as shown in Figure 13(d), the CG-NCMA oxide cathode showed nearly identical dQ / dV curves after 100 charge-discharge cycles at a 1C charge-discharge rate. Thus, the CG-NCMA oxide cathode fabricated by the method of the present invention possesses excellent internal structural stability and can effectively improve the electrochemical performance of lithium-ion batteries.

[0085] The reversibility of electrochemical reactions at the positive electrodes of lithium-ion batteries was analyzed by cyclic voltammetry (CV). The results of the first three cycles of the UC-NCMA oxide positive electrode and the CG-NCMA oxide positive electrode are shown in Figure 14(a) and Figure 14(b), respectively. Qualitative analysis was performed on the voltages at which the electrochemical reactions and electron transfer occurred at the electrodes. A typical CV curve has three pairs of oxidation and reduction peaks, and the Li + The H1⇔M⇔H2 phase transition due to ion intercalation and deintercalation is shown. The delayed dynamic response of the H1→M phase transition during the initial delithiation process resulted in a slightly higher oxidation potential. Furthermore, after activation by the first cycle, the symmetric redox peaks in the second and third cycles nearly overlapped, indicating the excellent electrochemical reversibility of the cathode material.

[0086] The polarization voltage is defined as the difference (ΔV) between the first negative and positive peaks (H1⇔M) during the first activation cycle, which are approximately 3.7–4.0 V. It is a measure of the reversibility of the cathode material. The ΔV values ​​for the first negative and positive peaks (H1⇔M) of the CG-NCMA oxide cathode and the UC-NCMA oxide cathode are 192.7 mV and 211.6 mV, respectively. The lower polarization voltage of the CG-NCMA oxide cathode indicates its higher structural stability and therefore its superior reversible kinetics.

[0087] Figure 14(c) and Figure 14(d) show the electrochemical impedance spectra of the UC-NCMA oxide cathode and the CG-NCMA oxide cathode, respectively, at the initial cycle and after 100 cycles at a charge-discharge rate of 1 C. All the curves have a curved region at high frequency (and medium frequency) and a linear region at low frequency. The EIS curves were fitted using the proposed equivalent circuit model. b is the bulk resistance and R sei is the solid electrolyte interphase (SEI) resistance, and R ct is the charge transfer resistance, CPE (Constant phase element) is the constant phase element, and Z W is the Li at the solid electrode + This is the Warburg impedance value that represents the ion diffusion resistance.

[0088] The electrochemical impedance spectra of the UC-NCMA and CG-NCMA oxide cathodes were fitted to their equivalent circuit models using the software ZView, and the obtained values ​​are shown in Table 3. The results in Table 3 show the initial R ct = 263.1 Ω is the initial R of the UC-NCMA oxide cathode ct = 355.6 Ω, which is much lower than the UC-NCMA oxide cathode. This means that when nickel-rich UC-NCMA-based cathodes are exposed to electrolytes, NiO-like inactive regions are likely to form on their surfaces, increasing the charge transfer resistance. Furthermore, as shown in Figure 14(d), after 100 cycles at a charge / discharge rate of 1 C / 1 C for the UC-NCMA oxide cathode and the CG-NCMA oxide cathode, both EIS curves are curved lines. Fitting these curves to an equivalent circuit model (inset in Figure 14(d)) revealed that the R ct In addition to the lower R sei = 66.7Ω, the R of the UC-NCMA oxide cathode sei = 95.4Ω, which is consistent with the experimental results above.

[0089] [Table 3]

[0090] During long-term cycling, active secondary particles are susceptible to impurities such as hydrofluoric fluoride (HF) generated in the electrolyte or unavoidable impurities resulting from side reactions. Therefore, the CG-NCMA oxide cathode with elemental concentration gradient prepared by the method of the present invention contains large amounts of manganese and aluminum elements in the outer and surface layers, respectively, which effectively suppresses side reactions at the interface between the cathode material and the electrolyte, prevents destruction of the electrode structure, and ultimately improves the electrochemical performance and cycling stability of the entire lithium-ion battery.

[0091] [In-situ X-ray diffraction analysis] One of the most important effects of the concentration gradient is to maximize the discharge capacity by confining the nickel-rich phase in the inner layer of the active material particles. However, the improvement in the cycle stability of the battery and the structural stability of the electrode cannot be entirely attributed to the concentration gradient. This is because the CG-NCMA oxide contains a large amount of nickel (Ni content 90%). Also, the volume change of the battery during charge-discharge cycles puts enormous pressure on the positive electrode structure. And since most of the expansion and contraction occurs in the c-axis direction, the distortion is anisotropic. Generally, Li + The anisotropic strain generated in the process of deintercalation (ie, charging) and subsequent intercalation (ie, discharging) of ions into the positive electrode is accommodated through the relative directions of the plane formed by the a-axis and b-axis.

[0092] To clarify the mechanism and cause of the battery capacity degradation, the change in lattice constant during the second charge-discharge cycle was measured using in-situ XRD. Figures 15(a) and 15(b) show the XRD patterns of the UC-NCMA and CG-NCMA oxide cathodes during the charge-discharge process, respectively. Contours were extracted from Figures 15(a) and 15(b) and compared for different characteristic peaks, as shown in Figures 16(a) and 16(b). During the charge process, the electrostatic repulsion between adjacent O layers causes the Li + As the ions desorbed from the positive electrode, the (003) characteristic peak continued to shift to the left (i.e., the lattice expanded along the c-axis). Furthermore, as shown in Figures 13(a)-(d) and 14(a)(b), the (003) characteristic peak rapidly decreased near 4.1 V due to the transition from the H2 phase to the H3 phase, and the diffraction angle shifted to a higher angle. This is called lattice contraction.

[0093] Furthermore, during the charging process, the ionic radius of the TM layer decreased, causing the (101) characteristic peak to shift to the right, i.e., the a-axis contracted. During the discharging process, the same process was repeated in the opposite direction. Upon completion of the discharge process, all peaks finally returned to their original Bragg positions. This demonstrated the structural reversibility of the NCMA-based cathode. Other peaks also followed the same shifting process, resulting in lattice expansion or contraction, respectively. Although both cathodes underwent the same charge-discharge cycle and underwent the same level of strain, the CG-NCMA oxide cathode showed less expansion and contraction during cycling, which contributes to the extended cycle life of lithium-ion batteries, as shown in Figure 16(b).

[0094] Table 4 and Figures 16(c) to 16(e) show the results of Li +These are the results of the lattice constant changes during the ion intercalation and deintercalation process. This revealed that the H⇔H⇔ phase transition was the largest. Specifically, the lattice change Δc = 1.92% in the (003) crystal plane of the CG-NCMA oxide cathode was much smaller than the Δc = 3.38% in the UC-NCMA oxide cathode. Furthermore, the lattice change Δa = 1.64% and lattice volume change Δvol = 3.78% in the (101) crystal plane of the CG-NCMA oxide cathode were much smaller than the Δa = 2.36% and Δvol = 7.80% in the UC-NCMA oxide cathode. Thus, the changes in the three lattice constants (Δa, Δc, and Δvol) showed the same trend.

[0095] [Table 4]

[0096] The in-situ X-ray diffraction analysis revealed that the primary particles of the CG-NCMA oxide cathode possess a unique one-dimensional needle-like spatial structure distribution and strong outward ductility, which effectively reduces the volume change of the CG-NCMA oxide cathode during deep charging and improves its cycle stability. Furthermore, anisotropic contraction and expansion of the randomly arranged primary particles leads to localized tensile and compressive stresses, resulting in microcracks and ultimately structural failure. On the other hand, when using a CG-NCMA oxide cathode, the manganese-rich regions and partial aluminum regions in the outer and surface layers of the active material particles suppress the high volume change that can occur in the structure during the charge and discharge process, significantly and effectively improving the electrochemical performance and stability of the CG-NCMA cathode material.

[0097] [Failure analysis] To clarify the effect of the concentration gradient on the structure and mechanical strength of the NCMA-based cathode, the NCMA-based / Li half-cell was disassembled after charge-discharge cycling, and the NCMA-based electrode after cycling was observed by XRD and SEM.

[0098] The lack of significant differences in the position, shape, and relative intensity of the characteristic peaks between the UC-NCMA and CG-NCMA oxide cathodes in the XRD patterns (Figure 17(a)) suggests that the capacity degradation of lithium-ion batteries is not solely due to the destruction or irreversible phase transformation of the electrode structure. However, as shown in the enlarged XRD pattern (Figure 17(b)), the (003) characteristic peak in the UC-NCMA oxide cathode is significantly shifted to lower angles compared to the CG-NCMA oxide cathode, with a Δ2θ difference of 0.54° from the (003) characteristic peak in the CG-NCMA oxide cathode. This suggests that long-term cycling leads to irreversible destruction of the active material particle structure in the UC-NCMA oxide, whereas the CG-NCMA oxide cathode is more resistant to mechanical stress during long-term cycling.

[0099] Figures 17(c) and 17(d) are SEM images of the UC-NCMA and CG-NCMA oxide cathodes, respectively, after 100 cycles at a high charge-discharge rate of 1C / 1C. + As ions repeatedly intercalate and deintercalate into the lattice, they generate mechanical stress, which leads to cracks along the grain boundaries of the primary particles and eventually to collapse. Figure 17(c) shows that the secondary particles of the UC-NCMA oxide cathode break down into a large number of primary particles after long-term cycling, meaning that the particle structure is not strong enough to withstand long-term charge-discharge cycling. In contrast, Figure 17(d) shows that the CG-NCMA oxide cathode remains structurally intact even after 100 cycles at high charge-discharge rates, although there are slight cracks in the secondary particles. This means that the structure of the CG-NCMA oxide cathode material is sufficiently reinforced to withstand the mechanical stress induced by long-term cycling at high charge-discharge rates. In addition, the manganese-rich distribution and aluminum element-containing distribution in the outer layer and surface layer of the CG-NCMA oxide cathode contribute to the stabilization of the structure of the CG-NCMA oxide cathode under conditions of high voltage (≧4.3V) and high charge / discharge rate (≧1C).

[0100] Next, we used focused ion beam (FIB) technology to section secondary particles of NCMA-based electrodes that had undergone charge-discharge cycling, and then used SEM to observe the internal structure of the longitudinal cross-sections of the sectioned particles. This allowed us to further investigate the extent of microcracks in the internal structure of secondary particles formed during long-term charge-discharge cycling in lithium-ion batteries. As shown in Figures 18(a) and 18(b), the UC-NCMA oxide cathode had more obvious cracks along the grain boundaries of the primary particles within the secondary particles. After repeated charge-discharge cycling, the primary particles began to separate, resulting in structural damage. In contrast, as shown in Figures 18(c) and 18(d), the CG-NCMA oxide cathode maintained perfect primary particle alignment and showed almost no cracks along the grain boundaries of the primary particles, even after repeated charge-discharge cycling.

[0101] Experimental results from FIB cutting of longitudinal sections demonstrated that UC-NCMA oxide cathodes are prone to microcracks at the grain boundaries of primary particles in their secondary particles after long-term charge-discharge cycling, leading to the extension and expansion of the cracks. Furthermore, subsequent electrolyte penetration and reaction accelerate the loss of mechanical integrity of the structure. Furthermore, as the surface area of ​​particles exposed to the electrolyte increases with extended battery cycling, the microstructure on the particle surface is severely damaged, resulting in particle fracture of the UC-NCMA oxide cathode. In contrast, the stable structure of the CG-NCMA oxide cathode, consisting of a manganese-rich outer layer and an aluminum-containing surface layer, effectively suppresses the initiation and expansion of microcracks and prevents the secondary particles from collapsing and pulverizing due to the formation of microcracks during long-term cycling.

[0102] After 100 charge-discharge cycles at a high charge-discharge rate of 1C / 1C, the surface structure of the active material particles of the UC-NCMA oxide cathode and the CG-NCMA oxide cathode were observed using TEM to observe the different degrees of phase change that continuously occurred during the charge-discharge cycle process. As shown in Figure 18(e), the primary particles of the UC-NCMA oxide cathode after long-term charge-discharge cycles showed frequent Li + During the intercalation and deintercalation of , a remarkable phase transition occurred. Among them, the selected area electron diffraction (SAED) pattern of region I showed a perfect R-3m layered structure with alternating layers of TM and Li ions, and the active Ni ions were observed at the edge of the particle. 4+ (This is a common phenomenon in nickel-rich oxide cathodes during charge-discharge cycling.) Therefore, a NiO-like Fm-3m surface layer was detected in region II. On the other hand, as shown in Figure 18(f), the NiO-like damage layer found in the CG-NCMA oxide cathode was limited to a region of approximately 1 nm at the edge of the particle, and therefore could not be distinguished by electron diffraction from the selected regions I and II.

[0103] Therefore, the present invention aims to provide a method for producing a nickel-rich cathode material for lithium-ion batteries, which can improve the electrochemical performance of lithium-ion batteries and the mechanical stability of the cathode material. In this method, a continuous Taylor vortex reactor is used to produce a CG-NCM precursor with an elemental concentration gradient by coprecipitation under suitable conditions, such as ambient temperature, pH, heating time, and supply rates of Aqueous Solution A and Aqueous Solution B. This precursor then produces a CG-NCMA oxide with high concentrations of manganese and aluminum distributed on its surface. EDS line scans demonstrated that the CG-NCMA oxide cathode material has a homogeneous structure with an elemental concentration gradient distribution (i.e., the nickel concentration gradually decreases from the inner layer to the outer layer, and the manganese concentration gradually increases from the inner layer to the outer layer), and that the surface layer also has a quaternary NCMA structure with a homogeneous aluminum distribution.

[0104] The CG-NCMA oxide cathode prepared by the method of the present invention has excellent electrochemical performance. At a charge / discharge rate of 20 mA / g, its initial discharge capacity is Q sp,dchg,ini = 209mAh / g, and its initial coulombic efficiency (ICE) was 89.4%, which was higher than the CE of the UC-NCMA oxide cathode (82.9%). After the CG-NCMA oxide cathode was subjected to 100 charge-discharge cycles at a charge-discharge rate of 1C / 1C, its capacity retention rate was CR 1-100 = 91.5%, and the capacity retention rate after 200 charge / discharge cycles was CR 1-200 =80.2%, both of which are far higher than those of the UC-NCMA oxide cathode (CR 1-100 =83.4% and CR 1-200 =64.1%).

[0105] Furthermore, cyclic voltammetry and differential capacitance-voltage analysis revealed a significant decrease in the voltage polarization of the CG-NCMA oxide cathode. In-situ X-ray diffraction analysis revealed the mechanical stress experienced by the electrode during the charge-discharge process and its impact on battery performance. The CG-NCMA oxide cathode experienced relatively little stress change, making its structure less susceptible to destruction. Furthermore, failure analysis using XRD and SEM on electrodes subjected to long-term charge-discharge cycles confirmed these experimental results. The analysis revealed that the secondary particles of the UC-NCMA oxide cathode material had already disintegrated into a large number of primary particles, while the secondary particles of the CG-NCMA oxide cathode material maintained a more intact structure.

[0106] From the above, the nickel-rich hydroxide precursor obtained by combining the continuous Taylor vortex reactor with the coprecipitation reaction has a homogeneous structure with a nickel-rich inner layer and a manganese-rich outer layer with an element concentration gradient distribution, which reduces interfacial impedance during lithium ion migration and increases the number of lithium ion migration paths. Furthermore, the nickel-rich oxide positive electrode material with an element concentration gradient distribution produced from the nickel-rich hydroxide precursor can improve the electrochemical performance of lithium ion batteries, such as charge / discharge speed and long-term cycle stability, as well as the structural stability of the nickel-rich positive electrode material.

[0107] The above examples are merely specific examples for explaining the present invention, and are intended to illustrate the features of the present invention, but are not intended to enumerate all forms of the technical concepts of the present invention, nor are they intended to limit the present invention to the forms of the technical concepts disclosed in the examples. Various modifications and variations within the scope of the present invention will be readily apparent to those skilled in the art. The selected and described embodiments are intended to provide a suitable interpretation of the principles and practical applications of the present invention, and those skilled in the art will understand that the present invention has various modifications and variations suitable for specific applications. [Explanation of symbols]

[0108] S11: The metal ion raw material is uniformly mixed with deionized water to prepare a metal ion mixed solution (aqueous solution A). S12: Dissolve the manganese source in deionized water to prepare aqueous solution B S13: Aqueous solution A, precipitant solution (aqueous solution C), and chelating agent solution (aqueous solution D) are poured into a continuous Taylor vortex reactor filled with deionized water to carry out the first coprecipitation reaction. S14: Pour aqueous solution B into a continuous Taylor vortex reactor to carry out the second coprecipitation reaction. S15: The precipitate from the second coprecipitation reaction is collected, washed with ethanol and deionized water to remove residual ions, and then dried in an oven to obtain a nickel-rich hydroxide precursor. S21: Disperse an aluminum source in ethanol, add a nickel-rich hydroxide precursor material, and mix to obtain a mixture. Heat the mixture until it is completely dry to obtain a mixture a. S22: Using a ball mill, the lithium source and mixture a in S21 are crushed and mixed with crushing balls to obtain mixture b. S23: Mixture b in S22 is subjected to three-stage calcination heat treatment in a high-temperature furnace.

Claims

1. A method for producing a nickel-rich hydroxide precursor material, which is a nickel-cobalt-manganese hydroxide, in which the molar ratio of nickel content to the entire precursor material is 50% or more, each layer has a layered structure containing nickel, cobalt, and manganese, and the nickel concentration is higher in the inner layer than in the outer layer, and the manganese concentration is lower in the inner layer than in the outer layer, (1) preparing an aqueous solution A in which a metal ion source is dissolved; preparing an aqueous solution B in which a manganese source is dissolved; An aqueous solution C in which a precipitant is dissolved is prepared, An aqueous solution D containing a chelating agent dissolved therein is prepared. pouring the aqueous solution A, the aqueous solution C, and the aqueous solution D into a continuous Taylor vortex reactor to carry out a first co-precipitation reaction for 2 to 7 hours; the metal ion source is a nickel source and a cobalt source; the nickel source is at least one selected from the group consisting of nickel sulfate, nickel oxalate, nickel acetate, nickel nitrate, nickel chloride, and nickel hydroxide; the cobalt source is at least one selected from the group consisting of cobalt sulfate, cobalt oxalate, cobalt carbonate, cobalt acetate, cobalt nitrate, cobalt chloride, and cobalt hydroxide; the manganese source is at least one selected from the group consisting of manganese sulfate, manganese oxalate, manganese carbonate, manganese citrate, manganese acetate, manganese nitrate, manganese phosphate, electrolytic manganese dioxide, and manganese oxide; (2) pouring the aqueous solution B into the continuous Taylor vortex reactor and carrying out a second coprecipitation reaction for 5 to 70 hours, the reaction temperature of the second coprecipitation reaction is 30°C to 80°C, the pH value of the reaction environment is 9.5 to 12.5, and the rotation speed of the inner cylinder of the continuous Taylor vortex reactor is 200 rpm to 1500 rpm; (3) washing the precipitate obtained through the second coprecipitation reaction and drying it in an oven to obtain the nickel-rich hydroxide precursor material; 1. A method for producing a nickel-rich hydroxide precursor material, comprising:

2. 2. The method for producing a nickel-rich hydroxide precursor material according to claim 1, wherein the concentration of the aqueous solution A is 1.6M to 1.92M.

3. 2. The method for producing a nickel-rich hydroxide precursor material according to claim 1, wherein the concentration of the aqueous solution B is 0.08M to 0.4M.

4. 2. The method for producing a nickel-rich hydroxide precursor material according to claim 1, wherein the concentration of the aqueous solution C is 2.0 M to 6.0 M, and the weight molar concentration ratio of the aqueous solution A to the aqueous solution C is 1:1 to 1:

5.

5. 2. The method for producing a nickel-rich hydroxide precursor material according to claim 1, wherein the concentration of said aqueous solution D is 2.5 M to 9.0 M, and the weight molar concentration ratio of said aqueous solution A to said aqueous solution D is 1:1 to 1:

5.

6. 2. The method for producing a nickel-rich hydroxide precursor material according to claim 1, wherein the drying temperature in the oven is 60 to 120°C, and the drying time is 6 to 24 hours.

7. 2. The method for producing a nickel-rich hydroxide precursor material according to claim 1, wherein the supply rates of the aqueous solution A and the aqueous solution B are 1.0 to 3.0 ml / min.

8. A method for producing a nickel-rich oxide positive electrode material using the method for producing a nickel-rich hydroxide precursor material according to claim 1, comprising: (a) dispersing an aluminum source in ethanol, adding and mixing the nickel-rich hydroxide precursor material to obtain a mixture, and heating the mixture at a temperature of 80°C until it is completely dried to obtain a mixture a, the aluminum source is at least one selected from the group consisting of aluminum hydroxide, aluminum oxalate, aluminum carbonate, aluminum sulfate, aluminum acetate, aluminum nitrate, and aluminum phosphate; (b) a step of grinding and mixing a lithium source and the mixture a in the step (a) in a molar ratio of 1:1.01 to 1:1.25 to obtain a mixture b, the lithium source is at least one selected from the group consisting of lithium hydroxide, lithium nitrate, lithium acetate, lithium chloride, lithium hydrogen phosphate, lithium phosphate, and lithium carbonate; (c) performing a three-stage calcination heat treatment on the mixture b in the step (b) to obtain the nickel-rich oxide positive electrode material; A method for producing a nickel-rich oxide cathode material, comprising:

9. 9. The method for producing a nickel-rich oxide positive electrode material according to claim 8, wherein the pulverization conditions are a ball mill rotation speed of 50 to 200 rpm and a pulverization time of 2 to 10 hours.

10. The method for producing a nickel-rich oxide positive electrode material according to claim 8, wherein the temperatures and times of the three-stage calcination heat treatment are respectively as follows: the temperature of the first stage is 100°C to 200°C and the time is 1 to 3 hours; the temperature of the second stage is 500°C to 600°C and the time is 4 to 8 hours; and the temperature of the third stage is 700°C to 800°C and the time is 10 to 40 hours, and the temperature rising rates of the three-stage calcination heat treatment are all 0.1 to 20°C / min.

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