Positive electrode material precursor for lithium batteries, its preparation method and application

Abstract

The present invention discloses a lithium battery positive electrode material precursor, its preparation method and its application. The positive electrode material precursor has the chemical formula Ni x Co y M z T p (OH) q The cathode material precursor comprises secondary particles in the form of microspheres formed by aggregation of primary particles, and the microspheres have a three-layer structure from the inside to the outside, i.e., an inner core layer, an intermediate layer and an outermost layer. The ratio of the intensity of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak, expressed by the peak height in the XRD diffraction pattern of the inner core layer of the microspheres, is 1.0-8.0. The cathode material prepared using the cathode material precursor has a high discharge specific capacity and good cycle stability, and can be used in high-performance lithium batteries.

Description

Detailed Description of the Invention

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to Chinese Patent Application No. 202110545464.0, filed on May 19, 2021, entitled "Positive Electrode Material Precursor and Its Preparation Method and Application," the contents of which are incorporated herein by reference in their entirety.

[0002] [Technical Field] The present application relates to the field of lithium batteries, and in particular to lithium battery positive electrode material precursors and methods for preparing and applications thereof.

[0003] [Background technology] With the spread of electric vehicles and mobile devices, the shipment volume of lithium-ion batteries is steadily increasing. Lithium-ion batteries are mainly composed of major materials such as positive electrodes, negative electrodes, separators, and electrolytes. In particular, the positive electrode material determines important indicators of lithium-ion batteries, such as energy density, cycle life, safety, and cost, and is a material that is attracting attention in the research field.

[0004] Currently available cathode materials include olivine-structured LiFePO4, spinel-structured LiMn2O4, layered-structured LiCoO2, and layered-structured ternary cathode materials. Among these, ternary cathode materials offer comprehensive advantages, such as high charge / discharge specific capacity and low cost, demonstrating enormous market demand and potential. The main drawbacks of ternary cathode materials are the need for further improvement in specific capacity and the problem of rapid capacity fade during cycling. Improving the specific capacity and cycling stability of ternary cathode materials is crucial for their commercial adoption. Currently, material performance is primarily improved through ion doping and surface coating modification. From the structural perspective of ternary materials, relatively little research has been done on improving their cycling stability.

[0005] Methods for synthesizing ternary positive electrode materials include high-temperature solid-state methods, coprecipitation, sol-gel methods, spray-drying, and combustion. Among these, the most common method for producing ternary positive electrode materials involves preparing a precursor material by coprecipitation and then reacting it with a lithium salt via a high-temperature solid-state reaction. The precursor material prepared by coprecipitation determines the electrical properties of the positive electrode material, including specific charge / discharge capacity, charge / discharge efficiency, and cycle stability, and is therefore key to the production of ternary positive electrode materials. CN107915263A discloses a method for preparing a ternary positive electrode material precursor using a coprecipitation method. Using a metal mixture solution of nickel, cobalt, and manganese as raw materials, a metal source solution, a complexing agent, aqueous ammonia, and a precipitating agent, sodium hydroxide, are co-flowed into a reactor in a stoichiometric ratio. The temperature is controlled to 20°C to 60°C, the pH to 11 to 12, and the rotation speed to 200 rpm to 500 rpm. The entire reaction is carried out under N2 protection, and precursor materials with sizes of 3.5 μm to 4.0 μm are obtained.

[0006] Coprecipitation can produce secondary microspheres formed by the aggregation of primary particles by controlling process parameters. However, controlling the morphology of the primary particles and the aggregate morphology to improve the performance of the material has always been a problem and a challenge.

[0007] Summary of the Invention The purpose of this application is to provide a cathode material precursor and its preparation and application. This cathode material precursor has a novel structure and morphology, and its aggregation morphology can be well controlled. The cathode material prepared therefrom has excellent electrochemical properties, high discharge specific capacity, and good cycle stability.

[0008] In order to achieve the above object, one aspect of the present application is a compound having the chemical formula Ni x Co y M z T p (OH) qProvided is a lithium battery cathode material precursor, where M is selected from Fe, Cr, Cu, Nd, Ge, Ti, Mg, W, Mo, Nb, Ca, Zn, Sn, Zr, Ga, Mn, Al, V, Sr, Ba, Hf, Ta, Y, La, Ce or combinations thereof, T is selected from F, P, B, N, S or combinations thereof, 0 < x ≤ 1, 0 ≤ y < 1, 0 ≤ z < 1, 0 ≤ p ≤ 0.5, and the value of q is such that the above chemical formula satisfies the principle of electrical neutrality. The cathode material precursor includes secondary particles in the form of microspheres formed by aggregation of primary particles. The microspheres have a three-layer structure from the inside to the outside, namely, an inner core layer, an intermediate layer, and an outermost layer. In the XRD diffraction pattern of the inner core layer of the microspheres, the ratio of the intensity of the diffraction peak of the (110) crystal plane to the diffraction peak of the (102) crystal plane represented by the peak height is 1.0 - 8.0.

[0009] In another aspect, the present application provides a method for preparing a lithium battery cathode material precursor. The cathode material precursor has the chemical formula Ni x Co y M z T p (OH) q where M is selected from Fe, Cr, Cu, Nd, Ge, Ti, Mg, W, Mo, Nb, Ca, Zn, Sn, Zr, Ga, Mn, Al, V, Sr, Ba, Hf, Ta, Y, La, Ce or combinations thereof, T is selected from F, P, B, N, S or combinations thereof, 0 < x ≤ 1, 0 ≤ y < 1, 0 ≤ z < 1, 0 ≤ p ≤ 0.5, and the value of q is such that the above chemical formula satisfies the principle of electrical neutrality. The method includes mixing a metal source solution, a precipitant solution, and a complexing agent solution in a reaction vessel and reacting them. The metal source includes a Ni source, an optional Co source, and an optional M source. The metal source solution optionally includes a T source. During the reaction step, the concentration of the complexing agent in the reaction system in the reaction vessel has an increasing trend, and the rate of change of the concentration of the complexing agent has a decreasing trend.

[0010] Preferably, during the reaction step, the concentration of the complexing agent in the reaction system continues to increase at a rate of change of more than 0 mol / L·h to 1 mol / L·h or less, preferably 0.001 mol / L·h to 1 mol / L·h, more preferably 0.001 mol / L·h to 0.5 mol / L·h, while the rate of change of the concentration of the complexing agent continues to decrease.

[0011] In another aspect, a positive electrode material precursor made by the method of the present application is provided.

[0012] In another aspect, the present application provides a lithium battery cathode material obtained by solid-state reaction of the cathode material precursor of the present application with a lithium source.

[0013] In another aspect, the present application provides a lithium battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator, wherein the positive electrode comprises the lithium battery positive electrode material of the present application.

[0014] The secondary particles of the cathode material precursor of the present application have a three-layer structure from the inside to the outside, and the inner core layer has a specific diffraction peak structure, i.e., the ratio of the intensity of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak is 1.0 to 8.0, preferably 1.2 to 4.0, and more preferably 1.5 to 3.5. This diffraction peak structure promotes lithium ion insertion and extraction in the inner core layer, effectively solving the problem of difficult utilization of the internal cathode active material and improving the specific discharge capacity and cycle stability of the cathode material. In a preferred embodiment, the secondary particles of the cathode material precursor have a specific diffraction peak structure different from that of the inner core layer, i.e., the ratio of the intensity of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak is 0.1 to 1.5, preferably 0.5 to 1.5, and more preferably 0.7 to 1.3. This diffraction peak structure has low activity, which is beneficial for stabilizing the interface of the positive electrode material and reducing side reactions between the interface and the electrolyte, further improving the cycling stability of the positive electrode material. When the positive electrode material prepared using the positive electrode material precursor was applied to lithium-ion batteries, the resulting lithium-ion batteries exhibited high discharge capacity, good rate performance, and excellent cycling stability. For example, in Example 1, the lithium battery using the resulting positive electrode material achieved an initial discharge specific capacity of 215.3 mAh / g at a 0.1 C rate, a coulombic efficiency of 91.2% during the first week, a discharge specific capacity of 190.3 mAh / g at a 1 C rate, and a capacity retention rate of 107.6% after 100 cycles at a 1 C rate, demonstrating the overall performance of high discharge specific capacity and good cycling stability.

[0015] The method for producing a positive electrode material precursor of the present application produces secondary particles having a three-layer structure by precisely controlling the concentration of a complexing agent in a reaction system and its rate of change, and the secondary particles and / or their inner core layer have a specific positive electrode material precursor with a diffraction peak structure. A lithium-ion battery using a positive electrode material produced from the positive electrode material precursor has high discharge capacity, good rate performance, and good cycle stability.

[0016] [Figure description] The following figures are used to provide a further understanding of the present application and constitute a part of this specification. They are used to explain the present application together with the following specific embodiments, but they are not intended to limit the present application. FIG. 1 is a schematic structural diagram of a cathode material precursor provided by the present application; FIG. 2 is an SEM image of the positive electrode material precursor prepared in Example 1 of the present application; FIG. 3 is an SEM image of a particle cross section of the positive electrode material precursor prepared in Example 1 of the present application; FIG. 4 is an XRD pattern of the inner core layer of the positive electrode material precursor prepared in Example 1 of the present application; FIG. 5 is an XRD pattern of the positive electrode material precursor prepared in Example 1 of the present application; FIG. 6 is a first cycle charge-discharge curve at 0.1 C rate of a lithium battery assembled from the cathode material prepared in Example 1 of the present application; FIG. 7 shows the cycle results of a lithium battery assembled from the cathode material prepared in Example 1 of the present application; FIG. 8 is a graph showing the change in the concentration of the complexing agent in the reaction system of Example 1 of the present application as a function of reaction time; FIG. 9 is a graph showing the concentration of complexing agent in the reaction system of Example 7 of the present application as a function of reaction time; FIG. 10 is a graph showing the concentration of complexing agent in the reaction system of Example 8 of the present application as a function of reaction time; FIG. 11 is an SEM image of the positive electrode material precursor prepared in Comparative Example 1 of the present application; FIG. 12 shows the cycle results of a lithium battery assembled from the cathode material prepared in Comparative Example 1 of the present application.

[0017] Detailed Description of the Invention The present application will be described in more detail below through specific embodiments. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not intended to limit the present application in any way.

[0018] Any specific numerical value disclosed herein, including the endpoints of a range, is understood to be not limited to that exact value, but to encompass values ​​approaching that exact value. Furthermore, for any disclosed range, any combination of the endpoints, the endpoints and any particular point within the range, and any particular point within the range, can yield one or more new numerical ranges, and these new ranges should also be considered to be specifically disclosed herein.

[0019] Unless otherwise explained, terms used herein have the same meaning as commonly understood by those skilled in the art. Where a term is defined herein and that definition differs from the common understanding in the art, the definition herein shall prevail.

[0020] In this application, the expression "satisfying the principle of electroneutrality" means that the algebraic sum of the valences of all elements in the corresponding chemical formula is zero.

[0021] In this application, secondary particles in the form of microspheres (also referred to herein as "secondary particle microspheres," "secondary microspheres," or "microspheres") may be spherical or spherical-like, e.g., ellipsoidal, but this application is not strictly limited thereto. Microspheres can be broadly classified into three-layer structures from the inside to the outside based on their porosity. A schematic diagram is shown in Figure 1. The "inner core layer" refers to the first segment region extending from the center of the microsphere to its outer surface, and its porosity is typically in the range of more than 5% and not more than 15%. The "intermediate layer" refers to the second segment region surrounding the inner core layer and extending from its outer surface to the outer surface of the microsphere, and its porosity is typically in the range of 0.01% to 5%. The "outermost layer" refers to the third segment region surrounding the intermediate layer and extending from its outer surface to the outer surface of the microsphere, and its porosity is typically in the range of 6% to 30%.

[0022] In this application, the porosity of the inner core layer, middle layer, and outermost layer of the microspheres is measured by the following method: precursor particles are attached to a conductive adhesive and mounted on a ThermoFisher focused ion beam scanning microscope (FIB-SEM) to perform three-dimensional reconstruction slice imaging. Three-dimensional reconstruction and void segmentation of the particles are then performed using Avizo software, and the porosity of the inner core layer, middle layer, and outermost layer is statistically calculated. The porosity is then determined by dividing the segmented void volume by the total volume of the corresponding region.

[0023] In this application, the XRD diffraction pattern of the secondary particles / microspheres of the positive electrode material precursor is measured by the following method: at the end of the reaction step, the positive electrode material precursor product is taken out, washed three times with deionized water, and dried and dehydrated in a vacuum drying oven at 120°C for 6 hours, and the dried product is measured by a D8 Advance SS model X-ray diffractometer manufactured by Bruker GmbH, Germany.

[0024] In this application, the XRD diffraction pattern of the inner core layer of the secondary particles / microspheres of the positive electrode material precursor is measured by the following method: 10 g of the obtained positive electrode material precursor product is added to 400 mL of a 0.4 mol / L hydrochloric acid solution, stirred for 15 minutes, filtered, washed three times with deionized water, and dried and dehydrated in a reduced pressure drying oven at 120°C for 6 hours to obtain an inner core layer product, which is measured using a D8 Advance SS model X-ray diffractometer manufactured by Bruker GmbH, Germany.

[0025] According to the present application, in the XRD spectra of the secondary particles / microspheres of the positive electrode material precursor and their inner core layer, the 2θ diffraction peaks located at 56° to 61° and 48° to 54° correspond to the (110) crystal plane and the (102) crystal plane, respectively. The intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak refers to the ratio of the peak height of the (110) crystal plane diffraction peak to the peak height of the (102) crystal plane diffraction peak.

[0026] In this application, the particle size of the secondary particles of the positive electrode material precursor refers to the median particle size D50 of the secondary microspheres, which can be measured through a dynamic light scattering technique, for example, a Mastersizer 3000 Laser Particle Size Analyzer from Malvern Panalytical, UK.

[0027] In the present application, when a lithium battery positive electrode material precursor is produced, the reaction can be terminated when the particle diameter D50 of the secondary particles of the precursor reaches a target particle diameter (usually 1 μm to 30 μm, preferably 1 μm to 20 μm, and more preferably 1 μm to 15 μm), and the moment when the reaction is terminated is referred to herein as the moment when the "reaction step is terminated." Accordingly, the "reaction step time" (or "total reaction time") in this specification refers to the time elapsed from the start of the reaction (i.e., the moment when the metal source solution, precipitant solution, and complexing agent solution start to be mixed in the reaction vessel) to the end of the reaction step.

[0028] In this application, the "rate of change" of the concentration of a complexing agent in a reaction system means the change in the concentration of the complexing agent in the reaction system per unit time, and is expressed in units of mol / L·h.

[0029] In the present application, when preparing a lithium battery positive electrode material precursor, the time from the moment T0 when the reaction starts to the moment T0 when the reaction step ends is N Divide the time period (i.e., the duration of the reaction step Tt) equally into N periods, record the end moment of the first period as T1, the end moment of the second period as T2, and so on, T0, T1, T2, T3, ...... and T N The concentrations of the complexing agent in the reaction system measured at the moment are C0, C1, C2, C3, ...... and C N The measured rates of change of the concentration of the complexing agent in the reaction system are recorded as R0, R1, R2, R3, ...... and R NDuring the reaction step, for at least one integer N of 4 or greater (e.g., one, two, or more integers between 4 and 100, between 5 and 50, or between 10 and 20), the concentration of complexing agent in the reaction system is recorded as C0 <C1<C2<C3<......<C N is satisfied, the concentration of the complexing agent in the reaction system is considered to be "trending to increase." Preferably, in the method for producing a positive electrode material precursor of the present application, the concentration of the complexing agent in the reaction system continues to increase throughout the reaction steps, and at this time, for any integer N equal to or greater than 4, the concentration of the complexing agent in the reaction system, excluding unavoidable disturbances, is considered to be "trending to increase." <C1<C2<C3<......<C N Similarly, during the reaction step, for at least one integer N equal to or greater than 4 (e.g., one, two, or more integers between 4 and 100, between 5 and 50, or between 10 and 20), the rate of change of the concentration of the complexing agent in the reaction system satisfies the following relationship: R0>R1>R2>R3>......>R N If the above condition is satisfied, the rate of change of the concentration of the complexing agent in the reaction system is considered to be "trending downward." Preferably, in the method for producing a positive electrode material precursor of the present application, the rate of change of the concentration of the complexing agent in the reaction system continues to decrease throughout the reaction steps, and in this case, for any integer N equal to or greater than 4, excluding unavoidable disturbances, the rate of change of the concentration of the complexing agent in the reaction system is in the following order: R0>R1>R2>R3>......>R N Meet the following.

[0030] In this application, unless expressly stated otherwise, any undescribed matter or item shall be directly applied to what is known in the art without any changes. Furthermore, any embodiment described herein can be freely combined with one or more other embodiments described herein, and the technical solutions or technical ideas formed thereby shall be considered part of the original disclosure or original record of this application, and shall not be considered as new matter not disclosed or anticipated in this specification, unless a person skilled in the art considers the combination to be obviously unreasonable.

[0031] All patent documents and non-patent documents (including, but not limited to, textbooks and journal articles) mentioned in this specification are incorporated herein by reference in their entirety.

[0032] In a first aspect, the present application provides a cathode material precursor having the chemical formula Ni x Co y M z T p (OH) q where M is selected from Fe, Cr, Cu, Nd, Ge, Ti, Mg, W, Mo, Nb, Ca, Zn, Sn, Zr, Ga, Mn, Al, V, Sr, Ba, Hf, Ta, Y, La, Ce or combinations thereof, T is selected from F, P, B, N, S or combinations thereof, 0 < x ≦ 1, 0 ≦ y < 1, 0 ≦ z < 1, 0 ≦ p ≦ 0.5, and the value of q is such that the above chemical formula satisfies the principle of electrical neutrality. The cathode material precursor includes secondary particles in the form of microspheres formed by aggregation of primary particles. These microspheres have a three-layer structure from the inside to the outside, namely, a core layer, an intermediate layer, and an outermost layer. In the XRD diffraction pattern of the core layer of the microspheres of the cathode material precursor of the present application, the ratio of the intensity of the diffraction peak of the (110) crystal plane to the diffraction peak of the (102) crystal plane, represented by the peak height, is 1.0 to 8.0, preferably 1.2 to 4.0, more preferably 1.5 to 3.5, for example 1.5, 2.0, 2.5, 3.0, 3.5, and any value within the range ending with any two of these values.

[0033] The inventors of the present application have found in the process of research that the specific diffraction peak structure of the core layer of the secondary particle microspheres of the cathode material precursor of the present application promotes the insertion and extraction of lithium ions in the core layer, effectively solves the problem that the utilization of the internal cathode active material is difficult, improves the discharge specific capacity and rate performance of the cathode material, and thereby improves the energy density and dynamic performance of the lithium ion battery.

[0034] In a preferred embodiment, the ratio of the intensity of the (110) crystal plane diffraction peak to the intensity of the (102) crystal plane diffraction peak, expressed as peak height in the XRD diffraction pattern of the secondary particle microspheres of the positive electrode material precursor, is 0.1 to 1.5, preferably 0.5 to 1.5, more preferably 0.7 to 1.3, for example, 0.8, 0.85, 0.9, 0.95, 1.0, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, or any value within a range formed by any two of these values ​​as endpoints.

[0035] During research, the inventors of the present application found that when the secondary particle microspheres of the cathode material precursor of the present application have the above-mentioned specific diffraction peak structure, the activity of the diffraction peak structure is low, which is effective in stabilizing the interface of the cathode material and further improving the cycle stability of the cathode material.

[0036] In a preferred embodiment, the shape of the primary particles of the precursor is at least one selected from the group consisting of a sheet, a lath, a needle, and a spindle, and more preferably, the shape of the primary particles of the precursor is a sheet, and the thickness thereof is 1 nm to 200 nm.

[0037] In this application, the morphology of the positive electrode material precursor is characterized by scanning electron microscopy (SEM). The scanning electron microscope used is a ZEISS Merlin (ZEISS GmbH, Germany). Through the SEM images of the positive electrode material precursor (shown in FIGS. 2 and 3), it can be observed that the positive electrode material precursor provided in this application has the morphology of microspheres. The microspheres are formed by the aggregation of flaky primary particles and have a three-layer structure from the inside to the outside, i.e., an inner core layer, a middle layer, and an outermost layer.

[0038] Furthermore, through SEM images of the positive electrode material precursor (shown in Figures 2 and 3), the aggregation density of the primary particles in the inner core layer, middle layer, and outermost layer of the microspheres can also be observed. This density can be characterized by the porosity of each layer (the lower the porosity, the higher the density). The thicknesses of the inner core layer, middle layer, and outermost layer can then be measured.

[0039] In a preferred embodiment, the porosity of the inner core layer is in the range of more than 5% but not more than 15%, the porosity of the intermediate layer is in the range of 0.01% to 5%, and the porosity of the outermost layer is in the range of 6% to 30%. More preferably, the porosities of the inner core layer, intermediate layer, and outermost layer of the microspheres satisfy the relationship intermediate layer<inner core layer≦outermost layer.

[0040] In a more preferred embodiment, the thickness of the inner core layer, the intermediate layer, and the outermost layer of the microspheres, when the total thickness of the three-layer structure is 100%, are 0.1% to 50%, 40% to 95%, and 0.1% to 20%, respectively. Preferably, the thickness of the inner core layer, the intermediate layer, and the outermost layer are 5% to 40%, 50% to 85%, and 1% to 15%, respectively.

[0041] For example, as can be seen from the SEM images of the cathode material precursor shown in Figures 2 and 3, the inner core layer of the precursor's microspherical secondary particles is formed by the aggregation of flaky primary particles, with a relatively loose aggregation, and is approximately 1.2 μm thick. The outermost layer is also formed by the aggregation of flaky primary particles, with a looser aggregation than the inner core layer, and is approximately 0.25 μm thick. The intermediate layer between the inner core layer and the outermost layer is very densely aggregated, with a thickness of approximately 3.7 μm.

[0042] The inventors of this application have found that the inner core layer has a low density (i.e., a high porosity), which further reduces the resistance to lithium ion insertion and extraction in the core layer and, at the same time, effectively buffers the volumetric changes of the positive electrode active material during charge and discharge, thereby suppressing the problems of cracking and scattering caused by the volumetric expansion and contraction of the positive electrode active material during charge and discharge. The intermediate layer has the highest density and effectively encapsulates the highly active core layer structure, improving not only the cycle stability of the positive electrode active material but also the tap density of the positive electrode active material. The outermost layer has the lowest density and can quickly embed external lithium ions into the aggregate phase of the positive electrode material, effectively reducing the interfacial resistance of the positive electrode material and improving the rate performance of the positive electrode active material.

[0043] In a preferred embodiment, the particle size D50 of the secondary particles of the precursor is 1 μm to 30 μm, preferably 1 μm to 20 μm, more preferably 1 μm to 15 μm.

[0044] In a preferred embodiment, in the chemical formula of the cathode material precursor, M is selected from Fe, Cr, Cu, Ti, Mg, W, Mo, Nb, Ce, Nd, Ca, Zn, Sn, Zr, Ga, Hf, Mn, Al, or a combination thereof, preferably selected from Mn, Al, Ti, Mg, Cr, Hf, Nb, Ce, Nd, or a combination thereof, more preferably a combination of at least one of Mn, Al, or a combination of Mn and Al and at least one selected from Ti, Mg, Cr, Hf, Nb, Ce, and Nd.

[0045] In a preferred embodiment, in the chemical formula of the cathode material precursor, T is selected from F, P, B, or a combination thereof, more preferably B or F.

[0046] In a preferred embodiment, in the chemical formula of the cathode material precursor, x satisfies 0 < x < 1, preferably 0.2 < x < 1, more preferably 0.5 < x < 0.95.

[0047] In a preferred embodiment, in the chemical formula of the cathode material precursor, y satisfies 0 < y < 1, preferably 0 < y < 0.5, more preferably 0 < y < 0.25.

[0048] In a preferred embodiment, in the chemical formula of the cathode material precursor, z satisfies 0 < z < 1, preferably 0 < z < 0.5, more preferably 0 < z < 0.25.

[0049] In a preferred embodiment, in the chemical formula of the cathode material precursor, p satisfies 0 ≤ p ≤ 0.5, preferably 0 ≤ p ≤ 0.3, more preferably 0 ≤ p ≤ 0.1.

[0050] In a specific and more preferred embodiment, M is selected from Mn and / or Al. Particularly preferably, the chemical formula of the cathode material precursor is Ni x Co y Mn z (OH)2 or Ni x Co y Al z (OH)2, where 0.5 < x < 0.95, 0 < y < 0.25, 0 < z < 0.25, and x + y + z = 1.

[0051] In a second aspect, the present application provides a method for preparing a lithium battery cathode material precursor, and the cathode material precursor is Ni x Co y M z T p (OH) q having the chemical formula, M is selected from Fe, Cr, Cu, Nd, Ge, Ti, Mg, W, Mo, Nb, Ca, Zn, Sn, Zr, Ga, Mn, Al, V, Sr, Ba, Hf, Ta, Y, La, Ce or combinations thereof, T is selected from F, P, B, N, S or combinations thereof, 0 < x ≤ 1, 0 ≤ y < 1, 0 ≤ z < 1, 0 ≤ p ≤ 0.5, and the value of q is such that the above chemical formula satisfies the principle of electrical neutrality.

[0052] The method includes the step of mixing and reacting a metal source solution, a precipitating agent solution and a complexing agent solution in a reaction vessel, and the metal source includes a Ni source, an optional Co source and an optional M source. The metal source solution optionally includes a T source, and during the reaction step, the concentration of the complexing agent in the reaction system in the reaction vessel has an increasing trend, and the rate of change of the concentration of the complexing agent has a decreasing trend.

[0053] In a preferred embodiment, during the reaction step, the concentration of the complexing agent in the reaction system continues to increase at a rate of change greater than 0 mol / L·h and less than or equal to 1 mol / L·h, preferably 0.001 mol / L·h to 1 mol / L·h, more preferably 0.001 mol / L·h to 0.5 mol / L·h, and at the same time the rate of change of the concentration of the complexing agent continues to decrease.

[0054] In a more preferred embodiment, during the reaction step, the rate of change of the concentration of the complexing agent and the reaction time t generally satisfy a monotonically decreasing functional relationship. This application can satisfy this functional relationship such that the rate of change decreases as the reaction time t increases, and as long as its value is within the required range (that is, greater than 0 mol / L·h and less than or equal to 1 mol / L·h, preferably 0.001 mol / L·h to 1 mol / L·h, more preferably 0.001 mol / L·h to 0.5 mol / L·h), the specific form of this functional relationship is not strictly limited.

[0055] In a certain particularly preferred embodiment, during the reaction step, the functional relationship f(t) between the rate of change of the concentration of the complexing agent and the reaction time t is

Number

Number

Number

[0056] In a preferred embodiment, the concentration of the complexing agent at the end of the reaction step is controlled to be in the range of 0.05 mol / L to 2.0 mol / L, preferably in the range of 0.2 mol / L to 1.4 mol / L, more preferably in the range of 0.5 mol / L to 1.2 mol / L.

[0057] In a more preferred embodiment, the duration of the reaction step (i.e., the total reaction time) is recorded as Tt, and the concentration of the complexing agent in the reaction system is controlled to reach 80% of the concentration of the complexing agent at the end of the reaction step within a period of 0 to 1 / 4 Tt.

[0058] In a more preferred embodiment, the duration of the reaction step is recorded as Tt. During the first 1 / 8 Tt of the reaction (i.e., within the period from 0 to 1 / 8 Tt), the rate of change of the complexing agent concentration in the reaction system is controlled to be 0.021 mol / L·h or greater, preferably 0.021 mol / L·h to 1 mol / L·h, more preferably 0.021 mol / L·h to 0.5 mol / L·h, such as 0.021 mol / L·h, 0.026 mol / L·h, 0.031 mol / L·h, 0.036 mol / L·h, 0.041 mol / L·h, 0.046 mol / L·h, 0.5 mol / L·h, or any value within the range ending with any two of these values. Using this preferred embodiment, the discharge capacity, rate capability, and cycle stability of the prepared cathode material precursor can be significantly improved.

[0059] In a more preferred embodiment, the duration of the reaction step is recorded as Tt. The complexing agent in the reaction system is controlled within 1 / 12 Tt immediately before the end of the reaction step (i.e., within the period from 1 / 12 Tt to Tt), and the concentration change rate is less than 0.005 mol / L·h, preferably 0.001 mol / L·h to 0.005 mol / L·h, such as 0.001 mol / L·h, 0.0015 mol / L·h, 0.002 mol / L·h, 0.0025 mol / L·h, 0.003 mol / L·h, 0.0035 mol / L·h, 0.004 mol / L·h, 0.0045 mol / L·h, 0.005 mol / L·h, or any value within a range containing any two of these values. This preferred embodiment significantly improves the cycle stability of the resulting cathode material precursor.

[0060] The present inventors have conducted detailed studies on the precipitation reaction process used to prepare a positive electrode material precursor, and have found that by controlling the concentration of a complexing agent in the reaction system and the rate of change of the complexing agent concentration, precursor secondary particles in the form of microspheres formed by aggregation of primary particles can be obtained. At the same time, the aggregation morphology of the primary particles can be controlled so that the inner core layer of the secondary particle microspheres is relatively loosely aggregated, the middle layer is very densely aggregated, and the outermost layer is relatively loosely aggregated. It is also possible to control the secondary particle microspheres and / or their inner core layer to exhibit a specific diffraction peak structure. As a result, the positive electrode material precursor obtained by this control can have a higher specific discharge capacity and better cycle stability.

[0061] In a preferred embodiment, the metal source solution contains a T source, or the method further comprises adding a T source to the reaction system during the reaction step. More preferably, the molar ratio of the nickel source calculated on a metal element basis, the cobalt source calculated on a metal element basis, the M source calculated on a metal element basis, and the T source calculated as the T element is (0-1):(0-1):(0-1):(0-0.5) (provided that the molar amount of the nickel source is not 0), preferably (0.2-1):(0-0.5):(0-0.5):(0-0.3), and more preferably (0.5-0.95):(0-0.25):(0-0.25):(0-0.1).

[0062] In a preferred embodiment, in the chemical formula of the positive electrode material precursor, M is selected from Fe, Cr, Cu, Ti, Mg, W, Mo, Nb, Ce, Nd, Ca, Zn, Sn, Zr, Ga, Hf, Mn, Al, or a combination thereof, preferably selected from Mn, Al, Ti, Mg, Cr, Hf, Nb, Ce, Nd, or a combination thereof, and more preferably a combination of at least one selected from Mn, Al, or Mn and Al with at least one selected from Ti, Mg, Cr, Hf, Nb, Ce, and Nd.

[0063] In a preferred embodiment, in the chemical formula of the cathode material precursor, T is selected from F, P, B, or a combination thereof, more preferably B or F.

[0064] In a preferred embodiment, in the chemical formula of the cathode material precursor, x satisfies 0 < x < 1, preferably 0.2 < x < 1, more preferably 0.5 < x < 0.95.

[0065] In a preferred embodiment, in the chemical formula of the cathode material precursor, y satisfies 0 < y < 1, preferably 0 < y < 0.5, more preferably 0 < y < 0.25.

[0066] In a preferred embodiment, in the chemical formula of the cathode material precursor, z satisfies 0 < z < 1, preferably 0 < z < 0.5, more preferably 0 < z < 0.25.

[0067] In a preferred embodiment, in the chemical formula of the cathode material precursor, p satisfies 0 ≤ p ≤ 0.5, preferably 0 ≤ p ≤ 0.3, more preferably 0 ≤ p ≤ 0.1.

[0068] In a particularly more preferred embodiment, M is selected from Mn and / or Al. Particularly preferably, the chemical formula of the cathode material precursor is Ni x Co y Mn z (OH)2, or Ni x Co y Al z (OH)2, where 0.5 < x < 0.95, 0 < y < 0.25, 0 < z < 0.25, and x + y + z = 1.

[0069] In the present application, there is no particular limitation on the type of the metal source, and specific examples thereof include sulfates, nitrates, acetates, oxalates, hydrochlorides of the corresponding metals, or combinations thereof, but are not limited thereto.

[0070] In the present application, the type of nickel source (i.e., Ni source) is not particularly limited. Preferably, the nickel source is at least one selected from nickel sulfate, nickel nitrate, nickel acetate, nickel oxalate, and nickel chloride, and more preferably, the nickel source is at least one selected from nickel sulfate, nickel nitrate, nickel acetate, nickel oxalate, and nickel chloride.

[0071] In the present application, the type of cobalt source (i.e., Co source) is not particularly limited. Preferably, the cobalt source is at least one selected from the group consisting of cobalt sulfate, cobalt nitrate, cobalt acetate, cobalt oxalate, and cobalt hydrochloride, and more preferably, the cobalt source is at least one selected from the group consisting of cobalt sulfate, cobalt nitrate, cobalt acetate, and cobalt chloride.

[0072] In the present application, there are no particular limitations on the type of M source. Preferably, the M source is at least one selected from sulfate, nitrate, acetate, oxalate, and hydrochloride of M, and more preferably at least one of manganese sulfate, manganese nitrate, manganese acetate, manganese chloride, aluminum nitrate, chromium nitrate, magnesium nitrate, hafnium nitrate, niobium nitrate, cerium nitrate, neodymium nitrate, aluminum chloride, aluminum acetate, aluminum sulfate, zinc sulfate, magnesium sulfate, and titanium sulfate.

[0073] In a preferred embodiment, the molar concentration of the metal source solution, calculated on a metal element basis, is 0.01 mol / L to 5.0 mol / L, for example, 0.01 mol / L, 0.1 mol / L, 0.5 mol / L, 1.0 mol / L, 2.0 mol / L, 3.0 mol / L, 4.0 mol / L, 5.0 mol / L, or any value within a range formed by any two of these values ​​as endpoints, more preferably 0.01 mol / L to 4.0 mol / L, and even more preferably 0.5 mol / L to 4.0 mol / L.

[0074] In the present application, there is no particular limitation on the type of precipitant, as long as the metal source can carry out a precipitation reaction. Preferably, the precipitant is selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, and alkali metal bicarbonates, or a combination thereof, and the alkali metal is preferably selected from Na, K, and Li, or a combination thereof. More preferably, the precipitant is selected from sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, potassium carbonate, potassium bicarbonate, lithium hydroxide, lithium carbonate, lithium bicarbonate, or a combination thereof. In the examples of the present application, sodium hydroxide is used as an example for illustrative purposes, and the present application is not limited thereto.

[0075] In the present application, the concentration of the precipitant solution is not particularly limited. Preferably, the concentration of the precipitant solution is 0.01 mol / L to 16.0 mol / L, for example, 0.01 mol / L, 0.02 mol / L, 0.1 mol / L, 0.5 mol / L, 1.0 mol / L, 2.0 mol / L, 3.0 mol / L, 4.0 mol / L, 5.0 mol / L, 6.0 mol / L, 7.0 mol / L, 8.0 mol / L, 9.0 mol / L, 10.0 mol / L, 11.0 mol / L, 12.0 mol / L, 13.0 mol / L, 14.0 mol / L, 15.0 mol / L, 16.0 mol / L, and any value within a range formed by any two of these values ​​as endpoints, preferably 2 mol / L to 12.0 mol / L.

[0076] In the present application, the type of complexing agent is not particularly limited as long as it can form a complex with Ni, Co, and M in an aqueous solution, and is preferably selected from ammonium ion donors, alcoholamine complexing agents, aminocarboxylic acid complexing agents, hydroxylaminocarboxylic acid complexing agents, carboxylic acid complexing agents, thiocyanate complexing agents, or combinations thereof, with an ammonium ion donor being preferred.

[0077] In a preferred embodiment, the ammonium ion donor is selected from aqueous ammonia, ammonium oxalate, ammonium carbonate, ammonium hydroxide, or a combination thereof. In the examples of the present application, aqueous ammonia is taken as an example for illustrative purposes, and the present application is not limited thereto.

[0078] In a preferred embodiment, the alcohol amine complexing agent is selected from ethanolamine, diethanolamine, 2-dibutylaminoethanol, 2-diethylaminoethanol, N,N-diethylethanolamine, or a combination thereof.

[0079] In preferred embodiments, the aminocarboxylic acid complexing agent is selected from sodium nitrilotriacetate (NTA), potassium nitrilotriacetate, ethylenediaminetetraacetic acid and its salts (EDTA), diethylenetriaminepentaacetic acid (DTPA), or combinations thereof.

[0080] In a preferred embodiment, the hydroxylaminocarboxylic acid complexing agent is selected from hydroxyethylenediaminetetraacetic acid (HEDTA) and its salts, ethylene glycol bis(β-diaminoethyl)ethyl ether-N,N,N'N'-tetraacetic acid (EGTA) and its salts, dihydroxyglycine and its salts, or combinations thereof.

[0081] In a preferred embodiment, the carboxylic acid complexing agent is selected from the group consisting of oxalic acid and its salts, tartaric acid and its salts, citric acid and its salts, gluconic acid and its salts, carboxymethylhydroxymalonic acid (CMOM) and its salts, carboxymethylhydroxysuccinic acid (CMOS) and its salts, hydroxyethylaminoacetic acid (DHEG) and its salts, or combinations thereof.

[0082] In a preferred embodiment, the thiocyanate complexing agent is selected from sodium thiocyanate, potassium thiocyanate, ammonium thiocyanate, calcium thiocyanide, zinc thiocyanide, or combinations thereof.

[0083] In the present application, the concentration of the complexing agent solution is not particularly limited. Preferably, the concentration of the complexing agent solution is 0.01 mol / L to 16.0 mol / L, for example, 0.01 mol / L, 0.1 mol / L, 0.5 mol / L, 1.0 mol / L, 2.0 mol / L, 3.0 mol / L, 4.0 mol / L, 5.0 mol / L, 6.0 mol / L, 7.0 mol / L, 8.0 mol / L, 9.0 mol / L, 10.0 mol / L, 11.0 mol / L, 12.0 mol / L, 13.0 mol / L, 14.0 mol / L, 15.0 mol / L, 16.0 mol / L, or any value within a range formed by any two of these values ​​as endpoints, more preferably 2.0 mol / L to 15.0 mol / L.

[0084] In a preferred embodiment, a bottom liquid is added to the reaction vessel before the metal source solution, precipitant solution, and complexing agent solution are added to the reaction vessel. Preferably, the bottom liquid is water or an aqueous solution containing a complexing agent, and the volume of the bottom liquid is 0% to 100%, preferably 0% to 80%, and more preferably 10% to 60% of the volume of the reaction vessel. The concentration of the complexing agent in the bottom liquid is 0 mol / L to 1.8 mol / L, preferably 0.05 mol / L to 1.5 mol / L, and more preferably 0.1 mol / L to 1.0 mol / L.

[0085] In a further preferred embodiment, the concentration of the complexing agent in the bottom solution is at least 0.05 mol / L, preferably at least 0.1 mol / L, for example 0.1 mol / L to 0.7 mol / L lower than the concentration of the complexing agent in the reaction system at the end of the reaction step.

[0086] In the present application, the precipitation reaction conditions for promoting complete reaction of the metal source solution, precipitant solution, and complexing agent solution may include the following: a temperature of 20°C to 70°C, preferably 45°C to 60°C; a pH of 8 to 14, preferably 10 to 12; a total reaction time (Tt) of 10 hours or more, preferably 12 to 96 hours, and more preferably 12 to 48 hours; and the precipitation reaction is carried out under stirring conditions, with a stirring speed of 50 rpm to 1200 rpm, for example, 50 rpm, 80 rpm, 100 rpm, 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, or 1200 rpm, preferably 600 rpm to 1200 rpm.

[0087] According to the present application, the pH of the reaction system can be controlled to remain constant during the reaction step, or can be controlled to vary within the above range depending on the product target. In a preferred embodiment, the pH of the reaction system remains constant during the reaction step.

[0088] In a particularly preferred embodiment, the method of the present application comprises the following steps: (1) Add the bottom solution to the reaction vessel. (2) Adding a metal source solution optionally containing a T source, a precipitant solution, and a complexing agent solution to a reaction vessel, and mixing and reacting; The duration of reaction step (2) is defined as Tt, and the concentration of the complexing agent in the reaction system is controlled to be 80% or more of the concentration of the complexing agent at the end of the reaction step within a time range of 0 to 1 / 4Tt. The concentration of the complexing agent in the reaction system is controlled to continuously increase throughout the reaction step, with the rate of change of the concentration of the complexing agent continuously decreasing, the rate of change of the concentration of the complexing agent being greater than 0 mol / L·h and not more than 1 mol / L·h, preferably in the range of 0.001 mol / L·h to 1 mol / L·h, more preferably in the range of 0.001 mol / L·h to 0.50 mol / L·h, and even more preferably in the range of 0.001 mol / L·h to 0.20 mol / L·h. (3) The product obtained in (2) is subjected to solid-liquid separation and drying to obtain a cathode material precursor.

[0089] In the present application, the solid-liquid separation in step (3) is not particularly limited as long as it can separate the reaction product obtained after the precipitation reaction, and for example, filtration or centrifugation can be used.

[0090] In the present application, preferably, the product obtained by the solid-liquid separation in step (3) is washed, and the washing solvent is preferably water, more preferably hot water at a temperature of 30°C to 90°C.

[0091] In the present application, the drying method in step (3) can be a method commonly used in this field, such as vacuum drying, freeze drying, air drying, oven drying, etc., and vacuum-heat drying is preferred. The drying temperature and drying time are not particularly limited as long as the washed material can be dried. For example, the vacuum-heat drying temperature is 50°C to 150°C, and the drying time is 4 hours to 24 hours.

[0092] In a third aspect, the present application provides a positive electrode material precursor made by the method of the second aspect. The properties of the positive electrode material precursor were described in detail in the first aspect and will not be repeated here.

[0093] In a fourth aspect, the present application provides a cathode material comprising the solid-state reaction product of a lithium source and a cathode material precursor according to the first or third aspect.

[0094] In a preferred embodiment, the positive electrode material is obtained by mixing a positive electrode material precursor with a lithium source and performing a sintering process.

[0095] In the present application, the manner of mixing the positive electrode material precursor and the lithium source is not particularly limited as long as it ensures uniform mixing. Preferably, mixing can be performed using a high-speed mixer, a ball mill, or the like. The mixed materials are sintered in an atmospheric furnace, and the sintering atmosphere can be at least one of an inert atmosphere such as air, oxygen, and nitrogen.

[0096] In a preferred embodiment, the molar ratio of the lithium source to the battery cathode material precursor, calculated on an elemental metal basis, is 0.9 to 1.3:1, such as 0.9, 0.95, 1.00, 1.05, 1.10, 1.15, 1.20, 1.30, and any value in the range ending with any two of these values.

[0097] In the present application, the lithium source may be present in the form of a lithium salt, and the lithium salt is preferably at least one selected from lithium nitrate (LiNO), lithium chloride (LiCl), lithium carbonate (LiCO), and lithium hydroxide (LiOH), lithium oxide (LiO), lithium phosphate (LiPO), lithium dihydrogen phosphate (LiHPO), and lithium acetate (CHCOOLi).

[0098] In a fifth aspect, the present application provides a lithium-ion battery (also referred to herein as a "lithium battery") comprising the positive electrode material described in the fourth aspect.

[0099] During research, the inventors of the present application have found that by using the positive electrode material provided by the present application in a lithium ion battery, the specific discharge capacity, rate performance, and cycle stability of the lithium ion battery can be improved.

[0100] The lithium ion battery provided in this application may have a structure known to those skilled in the art. Generally, a lithium ion battery includes a positive electrode, a negative electrode, an electrolyte, and a separator. The positive electrode and the negative electrode can be fabricated by applying a positive electrode compound containing a positive electrode material or a negative electrode compound containing a negative electrode material onto a current collector, respectively, and drying the applied compound.

[0101] In the present application, a positive electrode compound can be prepared using a positive electrode material, a conductive agent, a binder, and a solvent.

[0102] In the present application, the conductive agent used in the positive electrode compound is not particularly limited as long as it has conductivity and is stable during charge and discharge. Preferably, the conductive agent is at least one selected from acetylene black, ketjen black, artificial graphite, natural graphite, carbon tubes, graphene, superconducting carbon, carbon nanofibers, carbon dots, aluminum powder, nickel powder, titanium oxide, and conductive polymers.

[0103] In the present application, the binder used in the positive electrode compound is not particularly limited as long as it can exert a binding effect between the positive electrode material, the conductive agent, and the current collector. Preferably, the binder is at least one selected from polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), aqueous acrylic resin, polytetrafluoroethylene (PTFE), polyvinyl butyral (PVB), ethylene-vinyl acetate (EVA), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoroethylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylic resin.

[0104] In the present application, the positive electrode current collector is not particularly limited as long as it has appropriate conductivity. Preferably, the material of the positive electrode current collector may be aluminum, nickel, copper, titanium, silver, stainless steel, or a carbon material. The positive electrode current collector can be processed into a foil, sheet, film, mesh, perforated, nonwoven fabric, or the like.

[0105] In a preferred embodiment, the solvent used for the cathode compound may be N-methylpyrrolidone.

[0106] In the present application, a negative electrode compound can be prepared using a negative electrode material, a conductive agent, a binder, and a solvent.

[0107] In this application, there is no particular limitation on the type of negative electrode material, and those skilled in the art can select it according to actual needs. Preferably, the negative electrode material is at least one selected from artificial graphite, natural graphite, soft carbon, hard carbon, mesophase microspheres (MCMB), carbon fiber, lithium metal, silicon, silicon oxide, lithium metal alloy, and lithium titanate.

[0108] In the present application, the conductive agent and binder used in the negative electrode compound are not particularly limited. Preferably, the types and amounts of the conductive agent and binder used in the negative electrode compound can be the same as those used in preparing the positive electrode compound.

[0109] In a preferred embodiment, the solvent used in the negative electrode compound may be water.

[0110] In the present application, the negative electrode current collector is not particularly limited as long as it has appropriate conductivity. Preferably, the material of the negative electrode current collector may be aluminum, nickel, copper, titanium, silver, stainless steel, or a carbon material, and the negative electrode current collector can be processed into a foil, sheet, film, mesh, perforated, nonwoven fabric, or the like.

[0111] In the present application, the electrolyte may be a solid electrolyte such as a polymer electrolyte or an inorganic solid electrolyte, or the electrolyte may be a liquid electrolyte.

[0112] In a preferred embodiment, the polymer electrolyte is at least one selected from polyvinyl alcohol, phosphate ester polymers, polyvinylidene fluoride, polyoxyethylene derivatives, polyoxypropylene derivatives, polyethylene derivatives, and polyester sulfides.

[0113] In a preferred embodiment, the inorganic solid electrolyte is selected from LiS, LiS-P2S5, LiI, Li-La-Zr-O, Li-Ge-VO, LiN, Li4SiO4, LiPON, LISION, Li-Al-Ti-P, Li3PO4-Li2S-SiS2, LiBH4, LiBH4-LiX (X = Cl, Br or I), LiBH4-LiNH2, LiNH2, Li3AlH6, Li2NH or Li2O-B2O3-P2O5.

[0114] In the present application, the liquid electrolyte is a solution of a lithium salt in a solvent. The solvent may be a non-aqueous solvent, and is preferably at least one selected from ethylene carbonate (EC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), propylene carbonate (PC), ethyl propyl carbonate (EPC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), methyl formate (MF), ethyl formate (Eft), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), and propyl butyrate (BP).

[0115] In a preferred embodiment, the lithium salt in the liquid electrolyte is at least one selected from lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium hexafluoroarsenate (LiAsF), lithium bisfluorosulfonimide (LiFSI), lithium bistrifluoromethanesulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium bisoxalatoborate (LiBOB), lithium difluorophosphate (LiPOF), lithium difluorooxalatophosphate (LiDFOP), and lithium tetrafluorooxalatoborate (LiTFOP).

[0116] In the present application, additives can be selectively added to the liquid electrolyte to improve the performance of the lithium-ion battery. The additives are preferably at least one selected from vinylene carbonate (VC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), tris(trimethylsilane)phosphate (TMSP), sulfonate cyclic quaternary ammonium salts, ethylene sulfite (DTO), dimethyl sulfite (DMS), 1-propene-1,3-sultone (PST), 4-propylethylene sulfate (PEGLST), diethyl sulfite (DES), adiponitrile (ADN), succinonitrile (SN), 1,3-propane sultone (1,3-PS), vinyl sulfate (DTD), and ethylene 4-methyl sulfate (PCS).

[0117] In this application, a separator is disposed between the positive electrode and the negative electrode to separate them. The separator may be any separator commonly used in this field, and preferably, the separator may be a polyolefin such as polyethylene, polypropylene, or a polyethylene-polypropylene composite material, or a glass fiber sheet or nonwoven fabric. When a solid electrolyte is used, the solid electrolyte may also be used as the separator.

[0118] The present application does not have any particular limitations on the method for fabricating the lithium ion battery, and the lithium ion battery can be fabricated by a conventional method in the art. Preferably, the method for fabricating the lithium ion battery includes: uniformly mixing a positive electrode material, a conductive agent, a binder, and a solvent, then coating the mixture on at least one surface of a positive electrode current collector, drying, rolling, slicing, and using the mixture as a positive electrode; uniformly mixing a negative electrode material, a conductive agent, a binder, and a solvent, then coating the mixture on at least one surface of a negative electrode current collector, drying, rolling, slicing, and using the mixture as a negative electrode; assembling the positive electrode, separator, and negative electrode into a battery core by laminating or winding, putting the battery core into a frame, injecting a liquid electrolyte, and then sealing it to obtain a lithium ion battery.

[0119] In the present application, the amounts of the positive electrode material / negative electrode material, conductive agent, and binder are not particularly limited. Preferably, based on the weight of the solid components of the positive electrode compound or negative electrode compound, the mass content of the positive electrode material or negative electrode material is 50 wt% to 99 wt%, the mass content of the conductive agent is 0.5 wt% to 25 wt%, and the mass content of the binder is 0.5 wt% to 25 wt%.

[0120] [Example] The present application will be further explained below with reference to examples, but the present application is not limited thereto. In the following examples and comparative examples, The molar ratio of each element in the positive electrode material precursor was measured using an inductively coupled plasma spectrometer (ICP-OES) from Agilent, USA, Varian 725 ES model. Scanning electron microscope (SEM) images were obtained using a ZEISS Merlin model scanning electron microscope (ZEISS, Germany). X-ray diffraction patterns (XRD) were measured using a Bruker D8 Advance SS model X-ray diffractometer in the scanning range of 10° to 70° and at a scanning speed of 5° / min. The median particle size D50 was obtained using a Mastersizer 3000 Laser Particle Size Analyzer (Malvern Panalytical, UK). In the particle size measurement process, water was used as the dispersion medium, and the precursor product was added under stirring. The resulting slurry opacity was approximately 9%. Particle size was measured three times and the average value was taken.

[0121] In the following examples and comparative examples, all raw materials involved are commercially available unless otherwise stated.

[0122] Example 1 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0123] (1) Preparation of cathode material precursor Calculated based on the metal elements, a metal source solution with a concentration of 2 mol / L was prepared, and the molar ratio of nickel, cobalt, and manganese in the metal source solution was 8:1:1. In the preparation method, nickel sulfate, cobalt sulfate, and manganese sulfate were used to prepare a NaOH solution with a concentration of 6 mol / L, and a complexing agent ammonia solution with an ammonia concentration of 6 mol / L was prepared.

[0124] The prepared metal source solution, NaOH solution, and complexing agent solution were simultaneously added to the reaction vessel under stirring to carry out the precipitation reaction. Ammonia solution was added to the reaction vessel in advance, occupying 30% of the vessel's volume, with an ammonia concentration of 0.5 mol / L. The initial volumetric flow ratio of the metal source solution to the complexing agent solution was controlled to 3, and then the supply flow rate of the complexing agent was controlled without changing the flow rate of the metal source solution. As a result, the complexing agent concentration in the system continued to increase, while the rate of change of the complexing agent concentration continued to decrease. Figure 8 shows the change in the complexing agent concentration in the system over reaction time, and the rate of change of the complexing agent concentration follows the functional relationship f(t) = 4 / (6 + t) 2The reaction temperature was 55°C, the total reaction time was 48 hours, the stirring speed during the reaction was 800 rpm, and the flow rate of the NaOH solution was controlled so that the pH value of the reaction system was maintained around 11.2 throughout the reaction. At the start of the reaction, the ammonia concentration in the reaction system was 0.5 mol / L, and the rate of change was 0.111 mol / L·h. After 6 hours, the ammonia concentration in the reaction system was 0.85 mol / L, and the rate of change was 0.028 mol / L·h. After 12 hours, the ammonia concentration in the reaction system was 0.97 mol / L, and the rate of change was 0.012 mol / L·h. After 24 hours, the ammonia concentration in the reaction system was 1.07 mol / L, and the rate of change was 0.0044 mol / L·h. After 36 hours, the ammonia concentration in the reaction system was 1.11 mol / L, and the rate of change was 0.0023 mol / L·h. At the end of the reaction, the ammonia concentration in the reaction system was approximately 1.13 mol / L, and the rate of change was 0.0014 mol / L·h. After the precipitation reaction was completed, the slurry was naturally cooled, filtered under reduced pressure, washed three times with deionized water, and then dried and dehydrated in a reduced pressure drying oven at 120° C. for 12 hours to obtain a positive electrode material precursor.

[0125] (2) Evaluation of cathode material precursors The resulting positive electrode material precursor had a molar ratio of Ni:Co:Mn of 0.798:0.101:0.101. The positive electrode material precursor prepared above was characterized using an SEM, as shown in Figure 2. As can be seen from Figure 2, the preparation method provided by the present application allows for the preparation of a positive electrode material precursor with good sphericity, and the positive electrode material precursor has secondary particles in the form of microspheres formed by aggregation of flaky primary particles.

[0126] To further analyze the aggregate morphology of the flaky primary particles, the cathode material precursor was sectioned using an ion beam and characterized using an SEM. Figure 3 shows an SEM image of the cross section of the cathode material precursor. From Figure 3, it can be seen that the cathode material precursor obtained using the preparation method provided herein has a three-layer structure from inside to outside: an inner core layer, an intermediate layer, and an outermost layer. The inner core layer is formed by the aggregation of flaky primary particles, while the inner core layer is relatively loosely aggregated. The inner core layer is approximately 1.2 μm thick and has a porosity of approximately 7.24%. The outermost layer is also formed by the aggregation of flaky primary particles and is more loosely aggregated than the inner core layer. The outermost layer is approximately 0.25 μm thick and has a porosity of approximately 9.65%. The intermediate layer between the inner core layer and the outermost layer is very densely aggregated. The intermediate layer is approximately 3.7 μm thick and has a porosity of approximately 3.31%.

[0127] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 1 was measured and found to be 10.3 μm.

[0128] 10 g of the cathode material precursor prepared above was added to 400 mL of 0.4 mol / L hydrochloric acid solution and stirred for 15 minutes. After filtration and washing with deionized water three times, the mixture was dried and dehydrated in a vacuum oven at 120°C for 6 hours to obtain the core layer product. The XRD spectrum of the inner core layer was measured. The results are shown in Figure 4. From Figure 4, the (110) crystal plane diffraction peak and the (102) crystal plane diffraction peak of the inner core layer can be confirmed, with the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak being 2.93.

[0129] The positive electrode material precursor prepared in Example 1 was subjected to X-ray diffraction analysis, and the results are shown in Figure 5. From Figure 5, the (110) crystal plane diffraction peak and the (102) crystal plane diffraction peak of the precursor can be confirmed, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak is 0.86.

[0130] (3) Preparation and evaluation of positive electrode materials The cathode material precursor prepared above was taken and thoroughly mixed with the lithium source LiOH·HO in a ball mill for 30 minutes, then the molar ratio of Li:(Ni+Co+Mn) was controlled to 1.05:1 and pre-baked in an oxygen atmosphere at 500°C for 4 hours. After that, it was baked at 900°C for 12 hours to carry out a solid-state reaction, yielding the cathode material.

[0131] The cathode material, conductive agent, and binder prepared above were uniformly mixed in an 8:1:1 mass ratio, then coated on aluminum foil. After drying, the mixture was sliced ​​and used as the cathode. Acetylene black was used as the conductive agent, a 10% polyvinylidene fluoride solution was used as the binder, metallic lithium was used as the anode, and American Celgard 2400 polypropylene separator was used as the separator. The electrolyte was a liquid electrolyte, a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) in a 1:1 volume ratio, and the solute was lithium hexafluorophosphate (LiPF6) with a molar concentration of 1 mol / L. The 2032-type button cells were assembled in an inert atmosphere glove box with moisture and oxygen concentrations below 0.1 ppm.

[0132] The electrochemical characteristics of the cathode material were measured over a charge / discharge voltage range of 2.5 V to 4.3 V. The initial discharge specific capacity at a 0.1 C rate was 215.3 mAh / g, the coulombic efficiency during the first week was 91.2%, the discharge specific capacity at a 1 C rate was 190.3 mAh / g, and the capacity retention after 100 cycles at a 1 C rate reached 107.6%, demonstrating high discharge specific capacity and excellent cycle stability. Specific electrochemical test results are shown in Figures 6 and 7.

[0133] Example 2 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0134] (1) Preparation of cathode material precursor Calculated based on the metal elements, a metal source solution with a concentration of 2 mol / L was prepared, and the molar ratio of nickel, cobalt, and aluminum in the metal source solution was 8:1.5:0.5. In the preparation method, nickel sulfate, cobalt sulfate, and manganese sulfate were used to prepare a NaOH solution with a concentration of 6 mol / L, and a complexing agent ammonia solution with an ammonia concentration of 6 mol / L was prepared.

[0135] The prepared metal source solution, NaOH solution, and complexing agent solution were simultaneously added to a reaction vessel under stirring to conduct a precipitation reaction. Ammonia solution, occupying 30% of the vessel volume, was added to the reaction vessel in advance, resulting in an ammonia concentration of 0.5 mol / L. The initial volumetric flow ratio of the metal source solution to the complexing agent solution was controlled at 5. Subsequently, the supply flow rate of the complexing agent was controlled without changing the flow rate of the metal source solution. As a result, the complexing agent concentration in the system continued to increase, while the rate of change in the complexing agent concentration continued to decrease. The change in the complexing agent concentration in the system with reaction time was essentially the same as in Example 1. The reaction temperature was 50°C, the total reaction time was 48 hours, the stirring speed during the reaction was 800 rpm, and the flow rate of the NaOH solution was controlled so that the pH value of the reaction system was maintained around 11.4 throughout the reaction. The ammonia concentration in the system at the end of the reaction was approximately 1.13 mol / L. After the precipitation reaction was completed, the slurry was naturally cooled, filtered under reduced pressure, washed three times with deionized water, and then dried and dehydrated in a reduced pressure drying oven at 120° C. for 12 hours to obtain a positive electrode material precursor.

[0136] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Al in the resulting positive electrode material precursor was 0.803:0.151:0.046. The fabricated positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The thickness of the inner core layer of the resulting positive electrode material precursor was approximately 1.16 μm, the porosity of the inner core layer was approximately 7.16%, the thickness of the outermost layer was approximately 0.27 μm, and the porosity of the outermost layer was approximately 8.98%. The thickness of the intermediate layer between the inner core layer and the outermost layer was approximately 3.82 μm, and the porosity of the intermediate layer was approximately 3.16%.

[0137] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 2 was measured and found to be 10.7 μm.

[0138] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 2.79, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 0.89.

[0139] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0140] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0141] Example 3 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0142] (1) Preparation of cathode material precursor A metal source solution with a concentration of 2 mol / L was prepared, calculated based on the metal elements, with a molar ratio of nickel, cobalt, and manganese in the metal source solution of 9:0.5:0.5. Nickel sulfate, cobalt sulfate, and manganese sulfate were used in the preparation method. A NaOH solution with a concentration of 6 mol / L was prepared, and a complexing agent ammonia solution with an ammonia concentration of 6 mol / L was prepared.

[0143] The procedure was carried out according to the method described in Example 1 to obtain a positive electrode material precursor.

[0144] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn in the resulting positive electrode material precursor was 0.901:0.050:0.049. The fabricated positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The resulting positive electrode material precursor had an inner core layer thickness of approximately 1.54 μm, a porosity of approximately 6.98%, an outermost layer thickness of approximately 0.59 μm, and a porosity of approximately 8.63%. The intermediate layer between the inner core layer and the outermost layer was approximately 3.92 μm thick, and a porosity of approximately 3.04%.

[0145] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 3 was measured and found to be 12.5 μm.

[0146] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 2.82, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 0.97.

[0147] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0148] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0149] Example 4 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0150] (1) Preparation of cathode material precursor A metal source solution with a concentration of 3 mol / L was prepared, calculated on a metal element basis. The molar ratio of nickel, cobalt, and manganese in the metal source solution was 6:2:2. Nickel sulfate, cobalt sulfate, and manganese sulfate were used to prepare a 5 mol / L NaOH solution, and a 5 mol / L ammonia solution as a complexing agent.

[0151] The procedure was carried out according to the method described in Example 1 to obtain a positive electrode material precursor.

[0152] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn in the resulting positive electrode material precursor was 0.603:0.198:0.199. The resulting positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The resulting positive electrode material precursor had an inner core layer thickness of approximately 1.17 μm, a porosity of approximately 6.35%, an outermost layer thickness of approximately 0.31 μm, and a porosity of approximately 9.32%. The intermediate layer between the inner core layer and the outermost layer was approximately 3.27 μm thick, and a porosity of approximately 3.28%.

[0153] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 4 was measured and found to be 9.7 μm.

[0154] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 2.53, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 0.87.

[0155] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0156] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0157] Example 5 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0158] (1) Preparation of cathode material precursor A metal source solution with a concentration of 5 mol / L was prepared, calculated based on the metal elements, and the molar ratio of nickel, cobalt, and manganese elements in the metal source solution was 8:1:1. In the preparation method, nickel sulfate, cobalt sulfate, and manganese sulfate were used to prepare a NaOH solution with a concentration of 15 mol / L, and a complexing agent ammonia solution with an ammonia concentration of 15 mol / L.

[0159] The procedure was carried out according to the method described in Example 1 to obtain a positive electrode material precursor.

[0160] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn in the resulting positive electrode material precursor was 0.797:0.101:0.102. The fabricated positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The resulting positive electrode material precursor had an inner core layer thickness of approximately 0.52 μm, a porosity of approximately 5.68%, an outermost layer thickness of approximately 0.22 μm, and a porosity of approximately 7.16%. The intermediate layer between the outermost layers was approximately 4.66 μm thick, and a porosity of approximately 2.36%.

[0161] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 5 was measured and found to be 10.8 μm.

[0162] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 2.08, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 0.96.

[0163] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0164] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0165] Example 6 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0166] (1) Preparation of cathode material precursor A metal source solution with a concentration of 0.5 mol / L was prepared, calculated on a metal element basis, and the molar ratio of nickel, cobalt, and manganese elements in the metal source solution was 8:1:1. In the preparation method, nickel sulfate, cobalt sulfate, and manganese sulfate were used to prepare an NaOH solution with a concentration of 2 mol / L, and a complexing agent ammonia solution with an ammonia concentration of 3 mol / L.

[0167] The procedure was carried out according to the method described in Example 1 to obtain a positive electrode material precursor.

[0168] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn in the resulting positive electrode material precursor was 0.803:0.101:0.096. The resulting positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The resulting positive electrode material precursor had an inner core layer thickness of approximately 1.85 μm, a porosity of approximately 12.4%, an outermost layer thickness of approximately 0.59 μm, and a porosity of approximately 23.2%. The intermediate layer between the inner core layer and the outermost layer was approximately 2.46 μm thick, and a porosity of approximately 4.80%.

[0169] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 6 was measured and found to be 9.8 μm.

[0170] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 1.94, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 1.04.

[0171] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0172] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0173] Example 7 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0174] (1) Preparation of cathode material precursor A metal source solution with a concentration of 2 mol / L was prepared, calculated based on the metal elements. The molar ratio of nickel, cobalt, and manganese in the metal source solution was 8:1:1. In the preparation method, nickel sulfate, cobalt sulfate, and manganese sulfate were used to prepare a NaOH solution with a concentration of 6 mol / L, and a complexing agent ammonia solution with an ammonia concentration of 6 mol / L.

[0175] The prepared metal source solution, NaOH solution, and complexing agent solution were simultaneously added to a reaction vessel under stirring to cause a precipitation reaction. Water occupying 40% of the vessel volume was added to the reaction vessel in advance. After controlling the initial volumetric flow ratio of the metal source solution to the complexing agent solution to 4, the supply flow rate of the complexing agent was controlled without changing the flow rate of the metal source solution. As a result, the concentration of the complexing agent in the system continued to increase, and the rate of change of the complexing agent concentration continued to decrease. Figure 9 shows the change in the complexing agent concentration in the system over reaction time. The rate of change of the complexing agent concentration is expressed by the functional relationship f(t) = 3.61 / (3.17 + t) 2 The reaction was carried out at a stirring speed of 800 rpm, a reaction temperature of 55°C, and a total reaction time of 48 hours. The flow rate of the NaOH solution was controlled so that the pH of the reaction system remained near 11.3 throughout the reaction. At the start of the reaction, the ammonia concentration in the reaction system was 0 mol / L·h, and the rate of change was 0.359 mol / L·h. At 12 hours, the ammonia concentration in the reaction system was 0.91 mol / L, and the rate of change was 0.016 mol / L·h. At 24 hours, the ammonia concentration in the reaction system was 1.01 mol / L, and the rate of change was 0.0049 mol / L·h. At 36 hours, the ammonia concentration in the reaction system was 1.05 mol / L, and the rate of change was 0.0024 mol / L·h. At the end of the reaction, the ammonia concentration in the reaction system was approximately 1.07 mol / L, and the rate of change was 0.0014 mol / L·h. After the precipitation reaction was completed, the slurry was naturally cooled, filtered under reduced pressure, washed three times with deionized water, and then dried and dehydrated in a reduced pressure drying oven at 120° C. for 12 hours to obtain a positive electrode material precursor.

[0176] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn in the resulting positive electrode material precursor was 0.796:0.103:0.101. The resulting positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The thickness of the inner core layer of the resulting positive electrode material precursor was approximately 1.38 μm, the porosity of the inner core layer was approximately 6.87%, the thickness of the outermost layer was approximately 0.28 μm, and the porosity of the outermost layer was approximately 8.74%. The thickness of the intermediate layer between the inner core layer and the outermost layer was approximately 3.54 μm, and the porosity of the intermediate layer was approximately 3.12%.

[0177] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 7 was measured and found to be 10.2 μm.

[0178] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 2.51, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 1.02.

[0179] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0180] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0181] Example 8 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0182] (1) Preparation of cathode material precursor A metal source solution with a concentration of 2 mol / L was prepared, calculated based on the metal elements, and the molar ratio of nickel, cobalt, and manganese in the metal source solution was 8:1:1. In the preparation method, nickel sulfate, cobalt sulfate, and manganese sulfate were used to prepare a NaOH solution with a concentration of 6 mol / L, and a complexing agent ammonia solution with an ammonia concentration of 6 mol / L.

[0183] The prepared metal source solution, NaOH solution, and complexing agent solution were simultaneously added to a reaction vessel under stirring to cause a precipitation reaction. An ammonia solution was added to the reaction vessel in advance, occupying 30% of the vessel's volume, with an ammonia concentration of 0.5 mol / L. After controlling the initial volumetric flow ratio of the metal source solution to the complexing agent solution to 3, the supply flow rate of the complexing agent was controlled without changing the flow rate of the metal source solution. As a result, the complexing agent concentration in the system continued to increase, while the rate of change of the complexing agent concentration continued to decrease. Figure 10 shows the change in the complexing agent concentration in the system over reaction time. The rate of change of the complexing agent concentration is expressed by the functional relationship f(t) = 2.1 / (6.78 + t) 2 The reaction was carried out at a stirring speed of 800 rpm, a reaction temperature of 55°C, and a total reaction time of 24 hours. The flow rate of the NaOH solution was controlled so that the pH of the reaction system remained near 11.6 throughout the reaction. The ammonia concentration in the reaction system at the start of the reaction was 0.5 mol / L, with a rate of change of 0.046 mol / L·h. At 6 hours, the ammonia concentration in the reaction system was 0.65 mol / L, with a rate of change of 0.013 mol / L·h. At 12 hours, the ammonia concentration in the reaction system was 0.7 mol / L, with a rate of change of 0.006 mol / L·h. At 18 hours, the ammonia concentration in the reaction system was 0.73 mol / L, with a rate of change of 0.0034 mol / L·h. At the end of the reaction, the ammonia concentration in the reaction system was approximately 0.74 mol / L, with a rate of change of 0.0022 mol / L·h. After the precipitation reaction was completed, the slurry was naturally cooled, filtered under reduced pressure, washed three times with deionized water, and then dried and dehydrated in a reduced pressure drying oven at 120° C. for 12 hours to obtain a positive electrode material precursor.

[0184] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn in the resulting positive electrode material precursor was 0.795:0.102:0.103. The fabricated positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The resulting positive electrode material precursor had an inner core layer thickness of approximately 0.83 μm, a porosity of approximately 7.04%, an outermost layer thickness of approximately 0.18 μm, and a porosity of approximately 8.83%. The intermediate layer between the first and outermost layers was approximately 2.39 μm thick, and a porosity of approximately 3.22%.

[0185] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 8 was measured and found to be 6.5 μm.

[0186] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 2.25, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 0.91.

[0187] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0188] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0189] Example 9 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0190] (1) Preparation of cathode material precursor The procedure was carried out in accordance with the method described in Example 1, except that the pH value of the system was controlled to 14, to obtain a positive electrode material precursor.

[0191] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn in the resulting positive electrode material precursor was 0.802:0.101:0.097. SEM testing of the resulting positive electrode material precursor yielded SEM images similar to those shown in Figures 2 and 3. The thickness of the inner core layer of the resulting positive electrode material precursor was approximately 1.76 μm, the porosity of the inner core layer was approximately 10.3%, the thickness of the outermost layer was approximately 0.98 μm, and the porosity of the outermost layer was approximately 18.4%. The thickness of the intermediate layer between the inner core layer and the outermost layer was approximately 2.56 μm, and the porosity of the intermediate layer was approximately 4.72%.

[0192] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 9 was measured and found to be 10.3 μm.

[0193] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 1.62, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 1.23.

[0194] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0195] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0196] Example 10 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0197] (1) Preparation of cathode material precursor The procedure was carried out in accordance with the method described in Example 1, except that the pH value of the system was controlled at 8, to obtain a positive electrode material precursor.

[0198] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn in the resulting positive electrode material precursor was 0.791:0.102:0.107. The resulting positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The resulting positive electrode material precursor had an inner core layer thickness of approximately 0.36 μm, a porosity of approximately 5.90%, an outermost layer thickness of approximately 0.14 μm, a porosity of approximately 6.73%, and an intermediate layer between the inner core layer and the outermost layer thickness of approximately 5.3 μm, with a porosity of approximately 1.26%.

[0199] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 10 was measured and found to be 11.9 μm.

[0200] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 1.41, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 1.31.

[0201] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0202] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0203] Example 11 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0204] (1) Preparation of cathode material precursor The procedure was carried out in accordance with the method described in Example 1, except that the reaction temperature of the system was controlled at 70° C., to obtain a positive electrode material precursor.

[0205] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn in the resulting positive electrode material precursor was 0.796:0.096:0.108. The resulting positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The resulting positive electrode material precursor had an inner core layer thickness of approximately 0.61 μm, a porosity of approximately 6.22%, an outermost layer thickness of approximately 0.42 μm, and a porosity of approximately 7.12%. The intermediate layer between the first and outermost layers was approximately 4.07 μm thick, and a porosity of approximately 1.78%.

[0206] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 11 was measured and found to be 9.8 μm.

[0207] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 1.83. The intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 1.07.

[0208] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0209] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0210] Example 12 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0211] (1) Preparation of cathode material precursor The procedure was carried out in accordance with the method described in Example 1, except that the reaction temperature of the system was controlled at 20° C., to obtain a positive electrode material precursor.

[0212] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn in the resulting positive electrode material precursor was 0.801:0.102:0.097. The resulting positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The thickness of the inner core layer of the resulting positive electrode material precursor was approximately 1.45 μm, the porosity of the inner core layer was approximately 8.66%, the thickness of the outermost layer was approximately 0.62 μm, and the porosity of the outermost layer was approximately 13.79%. The thickness of the intermediate layer between the inner core layer and the outermost layer was approximately 3.33 μm, and the porosity of the intermediate layer was approximately 3.94%.

[0213] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 12 was measured and found to be 10.1 μm.

[0214] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 1.72, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 1.11.

[0215] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0216] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0217] Example 13 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0218] (1) Preparation of cathode material precursor The procedure was carried out in accordance with the method described in Example 1, except that the stirring speed of the system was controlled to 50 rpm, to obtain a positive electrode material precursor.

[0219] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn in the resulting positive electrode material precursor was 0.797:0.101:0.102. The resulting positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The resulting positive electrode material precursor had an inner core layer thickness of approximately 1.73 μm, a porosity of approximately 9.31%, an outermost layer thickness of approximately 0.52 μm, and a porosity of approximately 15.52%. The intermediate layer between the inner core layer and the outermost layer was approximately 3 μm thick, and a porosity of approximately 4.64%.

[0220] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 13 was measured and found to be 10.5 μm.

[0221] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 1.67, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 1.06.

[0222] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0223] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0224] Example 14 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0225] (1) Preparation of cathode material precursor The procedure was carried out in accordance with the method described in Example 1, except that the stirring speed of the system was controlled to 1200 rpm, to obtain a positive electrode material precursor.

[0226] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn in the resulting positive electrode material precursor was 0.801:0.102:0.097. The resulting positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The thickness of the inner core layer of the resulting positive electrode material precursor was approximately 1.15 μm, the porosity of the inner core layer was approximately 7.21%, the thickness of the outermost layer was approximately 0.27 μm, and the porosity of the outermost layer was approximately 9.46%. The thickness of the intermediate layer between the inner core layer and the outermost layer was approximately 3.68 μm, and the porosity of the intermediate layer was approximately 3.22%.

[0227] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 14 was measured and found to be 10.2 μm.

[0228] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 2.76, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 0.88.

[0229] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0230] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0231] Example 15 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0232] (1) Preparation of cathode material precursor A positive electrode material precursor was obtained by the same procedure as in Example 1, except that TiSO4 was added to the metal source solution to make Ti / (Ni+Co+Mn)=1 mol %.

[0233] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn:Ti in the resulting positive electrode material precursor was 0.798:0.101:0.101:0.0099. The fabricated positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The thickness of the inner core layer of the resulting positive electrode material precursor was approximately 1.32 μm, the porosity of the inner core layer was approximately 7.09%, the thickness of the outermost layer was approximately 0.24 μm, and the porosity of the outermost layer was approximately 9.03%. The thickness of the intermediate layer between the inner core layer and the outermost layer was approximately 3.64 μm, and the porosity of the intermediate layer was approximately 3.45%.

[0234] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 15 was measured and found to be 10.5 μm.

[0235] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 2.85, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 0.89.

[0236] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0237] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0238] Example 16 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0239] (1) Preparation of cathode material precursor A positive electrode material precursor was obtained by the same procedure as in Example 1, except that Mg(NO3)2 was added to the metal source solution to make Mg / (Ni+Co+Mn)=1 mol%.

[0240] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn:Mg in the resulting positive electrode material precursor was 0.801:0.102:0.097:0.0098. The fabricated positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The thickness of the inner core layer of the resulting positive electrode material precursor was approximately 1.47 μm, the porosity of the inner core layer was approximately 7.18%, the thickness of the outermost layer was approximately 0.28 μm, and the porosity of the outermost layer was approximately 9.32%. The thickness of the intermediate layer between the inner core layer and the outermost layer was approximately 3.5 μm, and the porosity of the intermediate layer was approximately 3.33%.

[0241] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 16 was measured and found to be 10.9 μm.

[0242] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 2.82, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 0.91.

[0243] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0244] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0245] Example 17 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0246] (1) Preparation of cathode material precursor A positive electrode material precursor was obtained by the same procedure as in Example 1, except that B2O3 was added to the metal source solution to make B / (Ni+Co+Mn)=1 mol %.

[0247] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn:B in the resulting positive electrode material precursor was 0.802:0.101:0.097:0.0095. The fabricated positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The thickness of the inner core layer of the resulting positive electrode material precursor was approximately 1.33 μm, the porosity of the inner core layer was approximately 7.06%, the thickness of the outermost layer was approximately 0.33 μm, and the porosity of the outermost layer was approximately 9.12%. The thickness of the intermediate layer between the inner core layer and the outermost layer was approximately 3.74 μm, and the porosity of the intermediate layer was approximately 3.38%.

[0248] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 17 was measured and found to be 10.4 μm.

[0249] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 2.83, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 0.88.

[0250] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0251] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0252] Example 18 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0253] (1) Preparation of cathode material precursor A positive electrode material precursor was obtained by the same procedure as in Example 1, except that Cr(NO3)3 was added to the metal source solution to make Cr / (Ni+Co+Mn)=1 mol%.

[0254] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn:Cr in the resulting positive electrode material precursor was 0.803:0.101:0.096:0.0097. The resulting positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The resulting positive electrode material precursor had an inner core layer thickness of approximately 1.44 μm, a porosity of approximately 6.69%, an outermost layer thickness of approximately 0.44 μm, and a porosity of approximately 8.25%. The intermediate layer between the inner core layer and the outermost layer was approximately 4.43 μm thick, and a porosity of approximately 2.96%.

[0255] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 18 was measured and found to be 12.5 μm.

[0256] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 3.37, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 1.14.

[0257] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0258] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0259] Example 19 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0260] (1) Preparation of cathode material precursor A positive electrode material precursor was obtained by the same procedure as in Example 1, except that Hf(NO3)4 was added to the metal source solution to make Hf / (Ni+Co+Mn)=1 mol %.

[0261] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn:Hf in the resulting positive electrode material precursor was 0.801:0.104:0.095:0.0099. The resulting positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The thickness of the inner core layer of the resulting positive electrode material precursor was approximately 1.51 μm, the porosity of the inner core layer was approximately 6.25%, the thickness of the outermost layer was approximately 0.39 μm, and the porosity of the outermost layer was approximately 8.36%. The thickness of the intermediate layer between the inner core layer and the outermost layer was approximately 5 μm, and the porosity of the intermediate layer was approximately 3.02%.

[0262] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 19 was measured and found to be 14 μm.

[0263] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 2.98, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 1.06.

[0264] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0265] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0266] Example 20 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0267] (1) Preparation of cathode material precursor A positive electrode material precursor was obtained by the same procedure as in Example 2, except that Nb(NO3)5 was added to the metal source solution to make Nb / (Ni+Co+Al)=1 mol%.

[0268] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Al:Nb in the resulting positive electrode material precursor was 0.802:0.151:0.047:0.0098. The resulting positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The resulting positive electrode material precursor had an inner core layer thickness of approximately 1.18 μm, a porosity of approximately 6.93%, an outermost layer thickness of approximately 0.31 μm, and a porosity of approximately 8.96%. The intermediate layer between the inner core layer and the outermost layer was approximately 2.8 μm thick, and a porosity of approximately 3.32%.

[0269] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 20 was measured and found to be 8.3 μm.

[0270] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 2.76. The intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 0.92.

[0271] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0272] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0273] Example 21 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0274] (1) Preparation of cathode material precursor A positive electrode material precursor was obtained by the same procedure as in Example 2, except that Ce(NO3)4 was added to the metal source solution to make Ce / (Ni+Co+Al)=1 mol%.

[0275] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Al:Ce in the resulting positive electrode material precursor was 0.801:0.149:0.05:0.0097. The resulting positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The thickness of the inner core layer of the resulting positive electrode material precursor was approximately 1.23 μm, the porosity of the inner core layer was approximately 6.73%, the thickness of the outermost layer was approximately 0.37 μm, and the porosity of the outermost layer was approximately 8.87%. The thickness of the intermediate layer between the inner core layer and the outermost layer was approximately 3.1 μm, and the porosity of the intermediate layer was approximately 3.16%.

[0276] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 21 was measured and found to be 9.5 μm.

[0277] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 2.77. The intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 0.93.

[0278] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0279] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0280] Example 22 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0281] (1) Preparation of cathode material precursor A positive electrode material precursor was obtained by the same procedure as in Example 2, except that Nd(NO3)3 was added to the metal source solution and Nd / (Ni+Co+Al)=1 mol%.

[0282] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Al:Nd in the resulting positive electrode material precursor was 0.798:0.151:0.051:0.0095. The fabricated positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The thickness of the inner core layer of the resulting positive electrode material precursor was approximately 1.00 μm, the porosity of the inner core layer was approximately 6.58%, the thickness of the outermost layer was approximately 0.26 μm, and the porosity of the outermost layer was approximately 8.55%. The thickness of the intermediate layer between the inner core layer and the outermost layer was approximately 3.64 μm, and the porosity of the intermediate layer was approximately 3.08%.

[0283] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 22 was measured and found to be 9.7 μm.

[0284] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 2.88. The intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 0.98.

[0285] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0286] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0287] Example 23 This example is used to illustrate the methods for making and evaluating the cathode material precursors and cathode materials described in this application.

[0288] (1) Preparation of cathode material precursor A positive electrode material precursor was obtained by the same procedure as in Example 2, except that NH4F was added to the metal source solution to make F / (Ni+Co+Al)=1 mol %.

[0289] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Al:F in the resulting positive electrode material precursor was 0.803:0.146:0.051:0.0087. The fabricated positive electrode material precursor was subjected to SEM testing, resulting in SEM images similar to those shown in Figures 2 and 3. The thickness of the inner core layer of the resulting positive electrode material precursor was approximately 1.14 μm, the porosity of the inner core layer was approximately 7.14%, the thickness of the outermost layer was approximately 0.42 μm, and the porosity of the outermost layer was approximately 9.02%. The thickness of the intermediate layer between the inner core layer and the outermost layer was approximately 3.54 μm, and the porosity of the intermediate layer was approximately 3.41%.

[0290] The median particle diameter D50 of the secondary microspheres of the positive electrode material precursor prepared in Example 23 was measured and found to be 10.2 μm.

[0291] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 2.73, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 0.88.

[0292] (3) Preparation and evaluation of positive electrode materials The cathode material and lithium-ion battery were fabricated according to the method described in Example 1.

[0293] The electrochemical characteristics of the positive electrode material were measured in the charge / discharge voltage range of 2.5 V to 4.3 V. Table 2 shows the specific results of the obtained discharge specific capacity, coulombic efficiency in the first week, and capacity retention rate after 100 cycles.

[0294] Comparative Example 1 (1) Preparation of cathode material precursor The operation was carried out according to the method described in Example 1, and a metal source solution with a concentration of 2 mol / L was prepared, calculated on a metal element basis, and the molar ratio of nickel, cobalt, and manganese elements in the metal source solution was 8:1:1. In the preparation method, nickel sulfate, cobalt sulfate, and manganese sulfate were used to prepare an NaOH solution with a concentration of 6 mol / L, and a complexing agent ammonia solution with an ammonia concentration of 6 mol / L.

[0295] The prepared metal source solution and NaOH solution were simultaneously dropped into a reaction vessel under stirring to induce a precipitation reaction. Ammonia solution was added to the reaction vessel in advance, amounting to 30% of the vessel's volume, with an ammonia concentration of 0.5 mol / L. The drop rate of the metal source solution was the same as in Example 1, and the drop rate of the NaOH solution was controlled so that the pH value of the reaction system was 11.2. Ammonia water (the total amount of ammonia used was the same as in Example 1) was divided into three equal portions and added to the reaction system 1 hour, 10 hours, and 30 hours after the start of the reaction. During the reaction, the stirring speed was controlled at 800 rpm, the reaction temperature was 55°C, and the total reaction time was 48 hours. After natural cooling, the precipitation reaction was terminated. The above slurry was filtered under reduced pressure, washed three times with deionized water, and then dried and dehydrated in a vacuum drying oven at 120°C for 12 hours to obtain a cathode material precursor.

[0296] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn in the obtained positive electrode material precursor was 0.802:0.101:0.097.

[0297] An SEM image of the prepared cathode material precursor is shown in Figure 11. This precursor is an irregular aggregate formed by loose aggregation of nanoparticles, and the sphericity of the particles is very low.

[0298] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 0.64, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 0.66.

[0299] (3) Preparation and evaluation of positive electrode materials The positive electrode material and lithium-ion battery were fabricated according to the method described in Example 1. The electrochemical properties of the positive electrode material were measured over a charge / discharge voltage range of 2.5 V to 4.3 V. The results showed that the initial discharge specific capacity at a 0.1 C rate was 172.3 mAh / g, the coulombic efficiency during the first week was 83.4%, the discharge specific capacity at a 1 C rate was 160.1 mAh / g, and the capacity retention after 100 cycles at a 1 C rate was 35.9% (shown in FIG. 12).

[0300] Comparative Example 2 (1) Preparation of cathode material precursor The operation was carried out according to the method described in Example 1, and a metal source solution with a concentration of 2 mol / L was prepared, calculated on a metal element basis, and the molar ratio of nickel, cobalt, and manganese elements in the metal source solution was 8:1:1. In the preparation method, nickel sulfate, cobalt sulfate, and manganese sulfate were used to prepare an NaOH solution with a concentration of 6 mol / L, and a complexing agent ammonia solution with an ammonia concentration of 6 mol / L.

[0301] The prepared metal source solution, NaOH solution, and complexing agent solution were simultaneously added to a reactor under stirring to initiate the precipitation reaction. Ammonia solution, occupying 30% of the reactor volume, was added to the reactor in advance, with an ammonia concentration of 0.5 mol / L. The initial volumetric flow ratio of the metal source solution to the complexing agent solution was controlled at 3. Subsequently, the flow rate of the metal source solution was not changed, and the complexing agent supply flow rate was controlled so that the complexing agent concentration in the system remained stable at approximately 0.5 mol / L until the reaction was completed. The flow rate of the NaOH solution was controlled so that the pH value of the reaction system remained near 11.2 throughout the reaction. The stirring speed during the reaction was 800 rpm, the reaction temperature was 55°C, and the total reaction time was 48 hours. After the precipitation reaction was completed, the mixture was naturally cooled, the slurry was filtered under reduced pressure, washed three times with deionized water, and then dried and dehydrated in a vacuum oven at 120°C for 12 hours to obtain a cathode material precursor.

[0302] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn in the obtained positive electrode material precursor was 0.801:0.103:0.096.

[0303] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 0.85, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 0.89.

[0304] (3) Preparation and evaluation of positive electrode materials The positive electrode material and lithium-ion battery were fabricated according to the method described in Example 1. The electrochemical properties of the positive electrode material were measured over a charge / discharge voltage range of 2.5 V to 4.3 V. The results showed that the initial discharge specific capacity at a 0.1 C rate was 198.4 mAh / g, the coulombic efficiency during the first week was 87.6%, the discharge specific capacity at a 1 C rate was 174.6 mAh / g, and the capacity retention after 100 cycles at a 1 C rate was 86.9%.

[0305] Comparative Example 3 (1) Preparation of cathode material precursor The operation was carried out according to the method described in Example 1, and a metal source solution with a concentration of 2 mol / L was prepared, calculated on a metal element basis, and the molar ratio of nickel, cobalt, and manganese elements in the metal source solution was 8:1:1. In the preparation method, nickel sulfate, cobalt sulfate, and manganese sulfate were used to prepare a NaOH solution with a concentration of 6 mol / L, and a complexing agent ammonia solution with an ammonia concentration of 6 mol / L.

[0306] The prepared metal source solution, NaOH solution, and complexing agent solution were simultaneously added to the reactor while stirring to initiate the precipitation reaction. Ammonia solution, occupying 30% of the reactor volume, was added to the reactor in advance, with an ammonia concentration of 0.5 mol / L. The initial volumetric flow ratio of the metal source solution to the complexing agent solution was controlled to 3. The flow rate of the complexing agent was then controlled so that the complexing agent concentration in the system increased linearly at a rate of 0.01 mol / L / h until the reaction was complete, without changing the flow rate of the metal source solution. The flow rate of the NaOH solution was controlled so that the pH of the reaction system remained near 11.2 throughout the reaction. The stirring speed during the reaction was 800 rpm, the reaction temperature was 55°C, and the total reaction time was 48 hours. After the precipitation reaction was complete, the mixture was naturally cooled, the slurry was filtered under reduced pressure, washed three times with deionized water, and then dried and dehydrated in a vacuum oven at 120°C for 12 hours to obtain a cathode material precursor.

[0307] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn in the obtained positive electrode material precursor was 0.797:0.101:0.102.

[0308] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 0.91, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 0.96.

[0309] (3) Preparation and evaluation of positive electrode materials The positive electrode material and lithium-ion battery were fabricated according to the method described in Example 1. The electrochemical properties of the positive electrode material were measured over a charge / discharge voltage range of 2.5 V to 4.3 V. The results showed that the initial discharge specific capacity at a 0.1 C rate was 203.4 mAh / g, the coulombic efficiency during the first week was 90.1%, the discharge specific capacity at a 1 C rate was 180.1 mAh / g, and the capacity retention after 100 cycles at a 1 C rate was 91.1%.

[0310] Comparative Example 4 (1) Preparation of cathode material precursor The operation was carried out according to the method described in Example 1. A metal source solution with a concentration of 2 mol / L, calculated on a metal element basis, was prepared, and the molar ratio of nickel, cobalt, and manganese elements in the metal source solution was 8:1:1. In the preparation method, nickel sulfate, cobalt sulfate, and manganese sulfate were used to prepare an NaOH solution with a concentration of 6 mol / L, and a complexing agent ammonia solution with an ammonia concentration of 6 mol / L.

[0311] The prepared metal source solution, NaOH solution, and complexing agent solution were simultaneously added to the reactor under stirring to initiate the precipitation reaction. Ammonia solution, occupying 30% of the reactor volume, was added to the reactor in advance, with an ammonia concentration of 0.5 mol / L. The initial volumetric flow ratio of the metal source solution to the complexing agent solution was controlled at 3. Subsequently, without changing the flow rate of the metal source solution, the complexing agent concentration in the system was controlled so that it remained stable at approximately 0.5 mol / L for the first 16 hours after the start of the reaction, approximately 0.8 mol / L from 16 to 32 hours, and approximately 1.1 mol / L from 32 to 48 hours. The flow rate of the NaOH solution was controlled so that the pH of the reaction system remained constant at approximately 11.2 throughout the entire reaction. During the reaction, the stirring speed was 800 rpm, the reaction temperature was 55°C, and the total reaction time was 48 hours. After the precipitation reaction was completed, the slurry was naturally cooled, filtered under reduced pressure, washed three times with deionized water, and then dried and dehydrated in a reduced pressure drying oven at 120° C. for 12 hours to obtain a positive electrode material precursor.

[0312] (2) Evaluation of cathode material precursors The molar ratio of Ni:Co:Mn in the obtained positive electrode material precursor was 0.798:0.102:0.100.

[0313] The prepared positive electrode material precursor and its inner core layer were subjected to XRD testing according to the method of Example 1. As a result, the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the inner core layer was 0.88, and the intensity ratio of the (110) crystal plane diffraction peak to the (102) crystal plane diffraction peak in the XRD spectrum of the precursor was 0.93.

[0314] (3) Preparation and evaluation of positive electrode materials The positive electrode material and lithium-ion battery were fabricated according to the method described in Example 1. The electrochemical properties of the positive electrode material were measured over a charge / discharge voltage range of 2.5 V to 4.3 V. The results showed that the initial discharge specific capacity at a 0.1 C rate was 200.2 mAh / g, the coulombic efficiency during the first week was 88.9%, the discharge specific capacity at a 1 C rate was 178.6 mAh / g, and the capacity retention after 100 cycles at a 1 C rate was 89.7%.

[0315] [Table 1]

[0316] [Table 2]

[0317] The above results demonstrate that the cathode material precursor of the present application differs from precursors in the prior art. The particles are secondary microspheres formed by the aggregation of flaky primary particles, and the microspheres have a three-layer structure from inside to outside: an inner core layer, a middle layer, and an outermost layer. The precursor and its inner core layer have a specific diffraction peak structure. This special structure endows the precursor with excellent electrochemical properties, such as high discharge specific capacity and excellent cycling stability, making it suitable for high-performance lithium batteries.

[0318] Although the preferred embodiments of the present application have been described in detail above, the present application is not limited to the specific contents of the above embodiments. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, and all of these simple modifications fall within the protection scope of the present application.

[0319] Furthermore, it should be noted that each of the specific technical features described in the above-mentioned specific embodiments can be combined in any suitable manner without contradiction, and in order to avoid unnecessary repetition, the various possible combinations will not be further described in this application.

[0320] Furthermore, it is possible to implement various embodiments of the present application in any combination, and as long as it does not contradict the concept of the present application, it should also be considered as the content disclosed in the present application. [Brief explanation of the drawings]

[0321] [Figure 1] 1 is a schematic structural diagram of a cathode material precursor provided by the present application. [Figure 2] 1 is an SEM image of the positive electrode material precursor prepared in Example 1 of the present application. [Figure 3] 1 is an SEM image of a particle cross section of a positive electrode material precursor prepared in Example 1 of the present application. [Figure 4] 1 is an XRD pattern of an inner core layer of a positive electrode material precursor prepared in Example 1 of the present application. [Figure 5] 1 is an XRD pattern of the positive electrode material precursor prepared in Example 1 of the present application. [Figure 6] 1 is a first cycle charge-discharge curve at 0.1 C rate of a lithium battery assembled from the positive electrode material prepared in Example 1 of the present application. [Figure 7] 1 shows the cycle results of a lithium battery assembled from the positive electrode material prepared in Example 1 of the present application. [Figure 8] FIG. 1 shows the change in the concentration of the complexing agent in the reaction system of Example 1 of the present application as a function of reaction time. [Figure 9] 1 is a graph showing the concentration of complexing agent as a function of reaction time in the reaction system of Example 7 of the present application. [Figure 10] 1 is a graph showing the concentration of complexing agent as a function of reaction time in the reaction system of Example 8 of the present application. [Figure 11] 1 is an SEM image of a positive electrode material precursor prepared in Comparative Example 1 of the present application. [Figure 12] 1 shows the cycle results of a lithium battery assembled from the positive electrode material prepared in Comparative Example 1 of the present application.

Claims

1. Chemical formula Ni ｘ Co ｙ M ｚ T ｐ (OH) ｑ wherein M is selected from Fe, Cr, Cu, Nd, Ge, Ti, Mg, W, Mo, Nb, Ca, Zn, Sn, Zr, Ga, Mn, Al, V, Sr, Ba, Hf, Ta, Y, La, Ce, or a combination thereof; and T is selected from F, P, B, N, S, or a combination thereof; a positive electrode material precursor, wherein 0<x≦1, 0≦y<1, 0≦z<1, 0≦p≦0.5, and the chemical formula satisfies the principle of electroneutrality depending on the value of q; the positive electrode material precursor comprises secondary particles in the form of microspheres formed by aggregation of primary particles, the microspheres having a three-layer structure from inside to outside, i.e., an inner core layer, a middle layer, and an outermost layer; and in an XRD diffraction pattern of the inner core layer of the microspheres, the ratio of the intensity of the diffraction peak of a (110) crystal plane to the diffraction peak of a (102) crystal plane, expressed in peak height, is 1.0 to 8.

0.

2. 2. The cathode material precursor according to claim 1, wherein the ratio of the intensity of the (110) crystal plane diffraction peak to the intensity of the (102) crystal plane diffraction peak, expressed as peak heights in an XRD diffraction pattern of the microspheres, is 0.1 to 1.

5.

3. In the above formula of the cathode material precursor: M is selected from Fe, Cr, Cu, Ti, Mg, W, Mo, Nb, Ce, Nd, Ca, Zn, Sn, Zr, Ga, Hf, Mn, Al, or combinations thereof; T is selected from F, P, B, or a combination thereof; x satisfies 0<x<1, y satisfies 0<y<1, z satisfies 0<z<1, p satisfies 0≦p≦0.5, The positive electrode material precursor according to any one of claims 1 to 2, wherein the chemical formula satisfies the principle of electroneutrality depending on the value of q.

4. The porosity of the inner core layer is in the range of more than 5% and not more than 15%, the porosity of the intermediate layer is in the range of 0.01% to 5%, and the porosity of the outermost layer is in the range of 6% to 30%; and 3. The cathode material precursor according to claim 1, wherein, of the total thickness of a three-layer structure of the microspheres, the thickness of the inner core layer accounts for 0.1% to 50%, the thickness of the intermediate layer accounts for 40% to 95%, and the thickness of the outermost layer accounts for 0.1% to 20%, respectively.

5. 3. The cathode material precursor according to claim 1, wherein the primary particles of the cathode material precursor have at least one shape selected from the group consisting of a sheet shape, a lath shape, a needle shape, and a spindle shape.

6. 3. The positive electrode material precursor according to claim 1, wherein the particle diameter D50 of the secondary particles of the positive electrode material precursor is 1 μm to 30 μm.

7. In an XRD diffraction pattern of the inner core layer of the microsphere, the ratio of the intensity of the (110) crystal plane diffraction peak to the intensity of the (102) crystal plane diffraction peak, expressed by peak height, is 1.5 to 3.5, and in an XRD diffraction pattern of the microsphere, the ratio of the intensity of the (110) crystal plane diffraction peak to the intensity of the (102) crystal plane diffraction peak, expressed by peak height, is 0.7 to 1.3; M is Mn, Al, or a combination of at least one of Mn and Al with at least one selected from Ti, Mg, Cr, Hf, Nb, Ce, and Nd; T is selected from B and F; x satisfies 0.5<x<0.95, y satisfies 0<y<0.25, z satisfies 0<z<0.25, p satisfies 0≦p≦0.1, the porosities of the inner core layer, the intermediate layer, and the outermost layer of the microspheres satisfy the relationship: porosity of the intermediate layer < porosity of the inner core layer ≦ porosity of the outermost layer; 3. The cathode material precursor according to claim 1, wherein, of the total thickness of a three-layer structure of the microspheres, the thickness of the inner core layer accounts for 5% to 40%, the thickness of the intermediate layer accounts for 50% to 85%, and the thickness of the outermost layer accounts for 1% to 15%, assuming that the total thickness of the three-layer structure is 100%.

8. The method for preparing a lithium battery cathode material precursor according to claim 1, wherein the cathode material precursor has the chemical formula Ni ｘ Co ｙ M ｚ T ｐ (OH) ｑ wherein M is selected from Fe, Cr, Cu, Nd, Ge, Ti, Mg, W, Mo, Nb, Ca, Zn, Sn, Zr, Ga, Mn, Al, V, Sr, Ba, Hf, Ta, Y, La, Ce or a combination thereof, and T is selected from F, P, B, N, S or a combination thereof; 0<x≦1, 0≦y<1, 0≦z<1, 0≦p≦0.5, and depending on the value of q, the chemical formula satisfies the principle of electroneutrality; The method includes a step of mixing and reacting a metal source solution, a precipitant solution, and a complexing agent solution in a reaction vessel, wherein the metal source includes a Ni source, an optional Co source, and an optional M source, and the metal source solution optionally includes a T source, and during the reaction step, the concentration of the complexing agent in the reaction system in the reaction vessel shows an increasing trend, while the rate of change of the concentration of the complexing agent shows a decreasing trend.

9. During the reaction step, the rate of change of the concentration of the complexing agent and the reaction time t satisfy a generally monotonically decreasing functional relationship; The functional relationship f(t) between the rate of change of the concentration of the complexing agent and the reaction time t is: [Equation 1] where a>0, b>0, c>1, and the values ​​of a, b, and c are [Equation 2] 9. The method of claim 8, wherein the rate of change of the concentration of the complexing agent f(t) is in units of mol / L h and the reaction time t is in units of h.

10. 10. The method according to claim 8 or 9, wherein the concentration of the complexing agent at the end of the reaction step is controlled in the range of 0.05 mol / L to 2.0 mol / L.

11. The rate of change of the concentration of the complexing agent in the reaction system is controlled to be 0.021 mol / L h or more during the period from 0 to 1 / 8 Tt, and / or 9. The method of claim 8, wherein the rate of change of the concentration of the complexing agent in the reaction system is controlled to be lower than 0.005 mol / L h during the period from 11 / 12 Tt to Tt, where Tt is the duration of the reaction step.

12. adding water or an aqueous solution containing a complexing agent as a bottom solution to the reaction vessel before adding the metal source solution, the precipitating agent solution, and the complexing agent solution to the reaction vessel; the concentration of the complexing agent in the bottom solution is 0 mol / L to 1.8 mol / L, and the concentration of the complexing agent in the bottom solution is at least 0.05 mol / L lower than the concentration of the complexing agent in the reaction system at the end of the reaction step; and / or The method according to any one of claims 8 to 9, wherein the volume of the bottom liquid is 0% to 100% of the volume of the reaction vessel.

13. In the formula of the positive electrode material precursor: M is selected from Fe, Cr, Cu, Ti, Mg, W, Mo, Nb, Ce, Nd, Ca, Zn, Sn, Zr, Ga, Hf, Mn, Al, or combinations thereof; T is selected from F, P, B, or a combination thereof; x satisfies 0<x<1, y satisfies 0<y<1, z satisfies 0<z<1, p satisfies 0≦p≦0.5, The method according to any one of claims 8 to 9, wherein the value of q causes the chemical formula to satisfy the principle of electroneutrality.

14. the metal source is selected from the group consisting of sulfates, nitrates, acetates, oxalates, hydrochlorides of the corresponding metals, or combinations thereof; the precipitating agent is selected from hydroxides, carbonates, bicarbonates of Na, K, Li, or combinations thereof; and / or 10. The method of any one of claims 8 to 9, wherein the complexing agent is selected from an ammonium ion donor, an alcoholamine complexing agent, an aminocarboxylic acid complexing agent, a hydroxylaminocarboxylic acid, a carboxylate salt, a thiocyanate complexing agent, or a combination thereof.

15. The method according to any one of claims 8 to 9, wherein the conditions of the reaction step include a temperature of 20°C to 70°C, a pH value of 8 to 14, a stirring speed of 50 rpm to 1200 rpm, and a duration Tt of the reaction step of 10 hours or more.

16. The concentration of the metal source solution is 0.01 mol / L to 5 mol / L, calculated on a metal element basis; The concentration of the precipitant solution is 0.01 mol / L to 16 mol / L; and The method according to any one of claims 8 to 9, wherein the concentration of the complexing agent solution is 0.01 mol / L to 16 mol / L.

17. The metal source solution includes a T source, or the method further includes adding a T source to the reaction system during the reaction step; The molar ratios of the nickel source, the cobalt source, the M source, calculated on a metal element basis, and the T source, calculated on a T element basis, are: The method according to any one of claims 8 to 9, wherein the molar amount of the nickel source is (0-1):(0-1):(0-1):(0-0.5) (provided that the molar amount of the nickel source is not 0).

18. 10. The method according to claim 8, wherein during the reaction step, a rate of change of the concentration of the complexing agent in the reaction system continues to increase at a rate of 0.001 mol / L h to 0.5 mol / L h, the concentration of the complexing agent at the end of the reaction step is controlled to be in the range of 0.5 mol / L to 1.2 mol / L, and the concentration of the complexing agent in the reaction system is controlled to reach 80% of the concentration of the complexing agent at the end of the reaction step within a period of 0 to ¼ Tt, where Tt is the duration of the reaction step, and the molar ratio of the nickel source, the cobalt source, the M source, calculated on a metal element basis, and the T source calculated on a T element basis is (0.5-0.95):(0-0.25):(0-0.25):(0-0.1).

19. A method for producing a lithium battery cathode material, comprising reacting the cathode material precursor according to any one of claims 1 to 2 in a solid state with a lithium source.

20. The lithium source is lithium nitrate (LiNO ３ ), lithium chloride (LiCl), lithium carbonate (Li ２ CO ３ ), lithium hydroxide (LiOH), lithium oxide (Li ２ O), lithium phosphate (Li ３ P.O. ４ ), lithium dihydrogen phosphate (LiH ２ P.O. ４ ), lithium acetate (CH ３ 20. The method of claim 19, wherein the ion exchange is selected from the group consisting of ion exchange, ion exchange (e.g., ion exchange), ...

21. 20. A method of making a lithium battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator, the method comprising making a lithium battery positive electrode material by the method of claim 19, wherein the positive electrode comprises the lithium battery positive electrode material.

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