Powder material of hydroxide or oxyhydroxide of one or more metal elements for preparing a positive electrode active material for a battery

Abstract

The present invention provides a powder material of hydroxide or oxyhydroxide of one or more metal elements for preparing a cathode active material for a battery, wherein the one or more metal elements include at least one of Ni, Co, and Mn, the powder material comprising particles having a core and a shell surrounding the core, wherein on a cross-section of the particle, the core has a total area (Ac) and the shell has a total area (As), the shell has a void area percentage of at least 20% and at most 99%, based on the total area (As) of the shell, as determined based on cross-sectional SEM image analysis, and the powder material has a void area percentage of at least 7.0 m 2 / g of BET specific surface area.

Description

[Technical Field]

[0001] The present invention relates to metal hydroxides that can be used as precursors for cathode active materials for secondary batteries. In particular, but not exclusively, the present invention relates to powder materials containing hydroxides or oxyhydroxides of at least one metal element, methods for producing the hydroxide or oxyhydroxide powder materials, and methods for producing cathode active materials for secondary batteries. [Background technology]

[0002] Lithium-ion secondary batteries typically include a negative electrode (anode), an electrolyte, and a positive electrode (cathode) containing a lithium transition metal oxide as an active material capable of intercalating and deintercalating lithium. Lithium transition metal oxides are typically prepared from transition metal hydroxides, oxides, or oxyhydroxides, commonly referred to as precursors, by a co-precipitation method that involves mixing a metal salt solution with an alkaline solution in the presence of a complexing agent. The cathode material manufacturing process generally involves mixing the precursor material with a lithium source, sintering, and optionally grinding.

[0003] Cathode materials are a key component of rechargeable batteries and have a significant impact on overall battery performance. Therefore, much research and development has been conducted in this field, including their precursors, in recent years. Some trends in cathode material development include, among others, improved capacity retention, higher energy density, improved stability and cycling performance, and lower cost. One approach to improving the properties of cathode materials is to optimize their microstructure, which is directly reflected by the microstructure of their precursors. And one approach to reducing costs is to produce these materials (cathode materials and / or their precursors) through more efficient processes.

[0004] In view of the above, there is a constant need for further improvements in precursors. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention aims to provide a powder material comprising hydroxides or oxyhydroxides of one or more metallic elements as a precursor to facilitate the manufacturing process of cathode active materials. [Means for solving the problem]

[0006] Viewed from a first aspect, the present invention provides a powder material of hydroxide or oxyhydroxide of one or more metal elements for preparing a positive electrode active material for a battery, the one or more metal elements including at least one of Ni, Co, and Mn, the powder material comprising particles having a core and a shell surrounding the core, the core having a total area A on a cross section of the particle. c and the shell has a total area A s and the shell has a total shell area A, as determined based on cross-sectional SEM image analysis. s Based on the above, the void area percentage is at least 20% and at most 99%.

[0007] For simplicity, such materials according to the present invention are also referred to herein simply as precursors. Precursors according to the present invention have the general formula: MO x (OH) 2-x where 0≦×≦2, and M represents an element(s), including at least one of Ni, Co, and Mn, and optionally at least one other element such as an impurity.

[0008] The shell of a particle is to be understood as the outer coating surrounding the particle, the shell being delimited by an outer interface and an inner interface, the inner interface being in contact with the core.

[0009] The void area percentage can be used to indicate the porosity of a material. Thus, the disclosed range of void area percentage of the article's shell indicates that the precursor according to the present invention has a porous shell zone. It has been found that the porous shell facilitates the manufacturing process of cathode materials. In particular, the powder material, i.e., precursor, according to the present invention, having a porous shell zone contributes to reducing particle agglomeration and / or avoiding over-sintering during the sintering process. Furthermore, a more porous shell results in less contact area between particles, which makes the grinding process much easier, e.g., less energy is required to grind the particles to a desired median particle size.

[0010] In a second aspect, the present invention provides a method for producing a cathode active material, the method comprising: mixing powder materials of hydroxides or oxyhydroxides of one or more metal elements according to the first aspect of the present invention, a lithium source, and an optional dopant source to obtain a mixture; and heating the mixture in an oxidizing atmosphere at a temperature of 650°C to 1000°C to obtain a positive electrode active material; and optionally, The method further comprises a step of heat treatment before mixing, wherein the powder material is heated at a temperature of 105°C to 750°C.

[0011] Various embodiments according to the present invention are disclosed in the claims and in this specification. The embodiments and examples listed in the claims and in this specification can be freely combined with each other unless otherwise expressly stated. Throughout this specification, when any numerical range is provided, the range also includes the endpoints unless otherwise expressly stated.

[0012] For reference, figures are attached to provide a better understanding of the teachings of the present invention. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 shows a scanning electron microscope (SEM) image of the particles obtained from Example 1. [Figure 2] 2a, 2b and 2c show SEM images based on void area analysis of the hydroxide particles obtained in Example 1. [Figure 3] FIG. 3 shows the average size D50 of the positive electrode active material of Example C and the positive electrode active material of Comparative Example C after 30 seconds of low-energy milling. [Figure 4] FIG. 4 shows the D50 of the positive cathode active material of Example C and the positive cathode active material of Comparative Example C, calcined at 820° C. after bead milling in water for 0, 3, 6, and 13 hours. DETAILED DESCRIPTION OF THE INVENTION

[0014] In the following detailed description, preferred embodiments are described in detail to enable the practice of the invention. Although the invention is described with reference to these specific preferred embodiments, it will be understood that the invention is not limited to these preferred embodiments. On the contrary, the invention includes numerous alternatives, modifications, and equivalents that will become apparent in light of the following detailed description and the accompanying drawings.

[0015] When used in the present specification and claims, the term "comprising" should not be interpreted as being limited to the means listed thereafter, nor does it exclude other elements or steps. It should be interpreted as specifying the presence of the mentioned and stated features, integers, steps, or components, but does not preclude the presence or addition of one or more other features, integers, steps, or components, or groups thereof. Thus, the scope of the expression "a composition comprising components A and B" should not be limited to a composition consisting only of components A and B. This means that, in the context of the present invention, the only relevant components in the composition are A and B. Thus, the terms "comprising" and "including" encompass the more restrictive terms "consisting essentially of" and "consisting of."

[0016] The term positive electrode active material (also known as cathode active material) as used herein and in the claims is defined as a material that is electrochemically active within the positive electrode or cathode. An active material should be understood to be a material that can capture and release Li-ions when subjected to a voltage change over a predetermined period of time.

[0017] As used in this disclosure, the term "cathode" is defined as a material that includes a cathode active material in addition to other components that are not electrochemically active, particularly a conductive agent such as a binder, such as carbon black or PVDF.

[0018] As used herein, the term "void area" refers to an empty area that is not occupied by a substance. Synonyms include empty area, hollow area, and the like.

[0019] The term "percent void area" is a measure of the amount of empty or unoccupied space in a given area, with higher values ​​indicating a higher proportion of void space, and may also be understood as the percentage of the area of ​​pores or the like.

[0020] As used herein, the term "porosity" refers to a measure of the void (i.e., "empty") space within a material, which is the ratio of the volume of the voids to the total volume.

[0021] As used herein, the term "total volume" refers to the volume of the solid matrix of a material as well as the volume of any voids or pores within the material.

[0022] In a first aspect, the present invention can provide a powder material of hydroxide or oxyhydroxide of one or more metal elements for preparing a positive electrode active material for a battery, the one or more metal elements including at least one of Ni, Co, and Mn, the powder material including particles having a core and a shell surrounding the core, the core having a total area (A c ) and the shell has a total area (A s) and the shell has a total shell area (A s As will be appreciated by those skilled in the art, the void area and void area percentage of the core and shell can be measured based on SEM images using suitable software, such as ImageJ software (ImageJ 1.52a, National Institutes of Health, USA).

[0023] For simplicity, such materials according to the present invention are also referred to herein simply as precursors. Precursors according to the present invention have the general formula: MO x (OH) 2-x where 0≦×≦2, and M represents an element(s), including at least one of Ni, Co, and Mn, and optionally at least one other element such as an impurity.

[0024] As mentioned above, the void area percentage can be used to indicate the porosity of a material. The powder material, i.e., precursor, according to the present invention, having a porous shell zone makes the grinding process much easier, as well as contributing to reducing particle agglomeration during sintering and / or avoiding over-sintering during the sintering process. In some embodiments, the void area percentage of the shell is at least 25%, preferably at least 30%, more preferably at least 50%.

[0025] In some embodiments, the shell has a percent void area of ​​at most 80%, or at most 70%, or at most 60%.

[0026] In some embodiments, the core of the particle has a void area percentage of up to 10%, more preferably up to 5%, and even more preferably up to 1%, as determined based on cross-sectional SEM image analysis. The disclosed core void area percentage ranges indicate a core zone with fewer pores, i.e., a denser core zone. Precursors with a denser core zone facilitate the cathode material manufacturing process in terms of throughput, for example, by allowing more precursor (or blend) to be loaded onto a tray in a single-step process. Furthermore, the denser cathode material, directly related to the precursor with a denser core zone, contributes to higher energy density due to a higher active material loading for the same electrode size.

[0027] In some embodiments, the particles have an average particle radius R1, an average core radius R2, and a ratio R between the average particle radius and the average core radius R1 / R2, where R≧1.00, preferably R≧1.50, and more preferably R≧2.00, where both R1 and R2 are obtained by averaging radius measurements of a representative number of particles and determined by SEM image analysis.

[0028] In some embodiments, the ratio R is R≦10, or R≦5, or R≦3. The larger the ratio R, the larger the porous shell zone in the precursor. The smaller the ratio R, the larger the dense core zone in the precursor. The disclosed ranges of R represent an optimized balance between the volume of the shell zone and the volume of the core zone occupied in the precursor, each of which provides advantages in different aspects as described above. The same idea can be presented as the percentage ratio between (R1-R2) and R1. Thus, in some embodiments, the percentage ratio between (R1-R2) and R1 is up to 90.0%, preferably up to 80.0%, and more preferably up to 60%.

[0029] In some embodiments, the powder material has a density of at least 7.0 m 2 / g, preferably at least 15.0m 2 / g, more preferably at least 20.0 m 2The precursor has a BET specific surface area of ​​1 / g. As will be understood by those skilled in the art, the specific surface area can be measured, for example, using the Brunauer-Emmett-Teller (BET) method, for example, by using Quantachrome Monosorb. The disclosed BET range makes the precursor according to the present invention particularly suitable for the production of monolithic cathode materials, since completely isolated particles can be obtained without mechanical damage and no fines form after grinding.

[0030] In the context of the present invention, a particle is considered to be single crystalline if it consists of only one grain or at most five grains, preferably at most three grains, as observed by scanning electron microscopy (SEM) or transmission electron microscopy (TEM), preferably by observing the grain boundaries of the particle. A grain boundary is defined as the interface between two grains within a particle, preferably where the atomic planes of the two grains are aligned in different orientations and meet as a crystalline discontinuity.

[0031] In certain preferred embodiments of the present invention, and in the context of the present invention, the single-crystal particles as defined herein are monolithic particles. As will be understood by those skilled in the art in these particular preferred embodiments, all embodiments relating to single-crystal particles apply equally to the monolithic particles as defined in the present invention.

[0032] In some embodiments, the particles have a median particle size D50, as determined by laser diffraction, of at least 2.0 μm and at most 10 μm, preferably at least 2.5 μm and at most 8 μm, and more preferably at least 3 μm and at most 5 μm. As will be understood by those skilled in the art, particle size distribution can be analyzed using a Malvern Mastersizer 3000 with a Hydro MV wet dispersion unit after dispersing sample particles in an aqueous medium. The disclosed median particle size ranges make the precursors according to the present invention particularly suitable for producing monolithic cathode materials, since the smaller the particle size of the precursor, the easier it is to obtain a monolithic cathode material.

[0033] In some embodiments, the powder material comprises: Ni with a content x, where x≧5.0 mol%, Mn having a content z, where 0≦y≦85.0 mol%, and Co having a content y, where 0≦z≦30.0 mol%, one or more additional elements in a content r from the list Al, B, Ba, Ca, Ce, Cr, Fe, La, Mg, Mo, Nb, Si, Sr, Ti, Y, V, W, Zn, and Zr, where 0≦r≦5.0 mol%, where x, y, z, and r are the contents expressed in mol% relative to the total molar content of the powder material, where x + y + z + r = 100.0 mol%. The values ​​x, y, z, and r are measured by inductively coupled plasma (ICP) method. It is understood that the formula ≧0 also includes the absence of an element.

[0034] In some embodiments, x≧60 mol%, or x≧70 mol%, or x≧80 mol%, or x≧90 mol%, and / or y≧20 mol%, and / or z≦25 mol%.

[0035] In some embodiments, the powder material has a span value (D90-D10) / D50 that is at most 1.00, preferably at most 0.80, more preferably at most 0.50, and even more preferably at most 0.30.

[0036] In some embodiments, the particles included in the powder material are secondary particles that include multiple primary particles.

[0037] The method for producing the precursor of the present invention generally includes, for example, providing an initiation solution comprising an aqueous slurry of seed particles to a reactor; feeding a stream of metal salt solution containing one or more metal elements into a reactor for a period of time (T1-T2); mixing the starting solution, the metal salt solution, and the aqueous solution containing one or more alkali hydroxides during a period T1-T2, thereby precipitating hydroxides of the one or more metal elements and forming an aqueous slurry containing hydroxides of the one or more metal elements; Here, during the period T1 to T2, in the reactor, a pH value which may vary or be kept constant within the range of 10.0 to 11.9, for example 10.0 to 11.0, preferably 10.2 to 10.7, measured on a sample of the aqueous slurry at 20°C; a concentration of NH3 of 1.0 g / l or more, preferably 15.0 g / l or less, preferably 1.5 g / l or more and 5 g / l or less; Optionally, maintaining a temperature of at least 60°C, preferably at least 70°C; and After the end of time period T2, the aqueous slurry in the reactor is further processed by separating the solid fraction from the liquid fraction and drying the solid fraction to obtain a powder material.

[0038] During the course of the manufacturing process, the precipitated hydroxides may be partially oxidized depending on the atmosphere of the manufacturing process. Thus, the aqueous slurry may contain oxyhydroxides. Also, during drying, the hydroxide or oxyhydroxide particles from the aqueous slurry may be further partially oxidized. Note that atmospheric conditions are not necessary to achieve the claimed invention.

[0039] As will be appreciated by those skilled in the art, the pH value can be measured by using a pH meter, for example, a 780 Metrohm meter. 3(aq) The concentration can be measured by using a commercially available titrator, for example, a Metrom 848 Titrino Plus.

[0040] In a second aspect, the present invention provides a method for producing a cathode active material, comprising: mixing powder materials of hydroxides or oxyhydroxides of one or more metal elements according to the first aspect of the present invention, a lithium source, and an optional dopant source to obtain a mixture; and heating the mixture in an oxidizing atmosphere at a temperature of 650°C to 1000°C to obtain a positive electrode active material; and optionally, The method further comprises a step of heat treatment before mixing, wherein the powder material is heated at a temperature of 105°C to 750°C.

[0041] In a third aspect, the present invention relates to the use of a hydroxide or oxyhydroxide powder material according to the first aspect of the invention in a positive electrode active material.

[0042] In a fourth aspect, the present invention relates to the use of a positive electrode active material produced according to the second aspect of the present invention in a secondary battery.

[0043] [Example] The present invention will be further illustrated with reference to some examples and comparative examples.In all examples, the pH value refers to the value measured at a temperature of 20°C.Furthermore, in all processes of the examples, unless otherwise indicated, a reducing atmosphere is ensured by applying a flow of nitrogen gas into the reactor during the precipitation reaction.

[0044] Measurement methods used in the examples A) pH analysis The pH values ​​of the samples were measured by a 780 Metrohm meter calibrated with standards pH 7 and pH 13. The pH was measured from the samples by cooling them to 20°C, placing a pH electrode into the sample, and waiting until the pH reading was constant.

[0045] B)NH 3(aq) Concentration analysis NH 3(aq)Concentrations were measured from reactor samples by endpoint titration using a Metrom 848 Titrino Plus instrument. One milliliter of sample solution was added to the titration vessel. 30-40 ml of deionized water and 1 ml of 1 M NaOH were added. The sample was titrated to the endpoint with 0.1 M HCl. As used herein, "NH 3(aq) "Concentration of" and the like terms refer to the concentration of ammonia in an aqueous solution.

[0046] C) Solid content analysis To measure the solids content of the precipitated hydroxide in the aqueous slurry, a sample taken from the aqueous slurry (referred to as "reaction mixture" in the examples) was mixed thoroughly, and 10-30 ml of the mixed sample was pipetted onto a filter paper, which was then washed and filtered onto a weighed 0.8 μm membrane. The filtered membrane was rinsed with DI water and then dried. The dried membrane was weighed, from which the solids content, expressed as the weight of dry hydroxide per liter of aqueous slurry in g / l, was calculated.

[0047] D) Surface area analysis The specific surface area (SA) of the exemplary samples was measured by the Brunauer-Emmett-Teller (BET) method by using Quantachrome Monosorb. Before the measurement, the powder sample was placed in a sample tube and heated at 90 °C for 2 h under nitrogen (N2) gas to remove adsorbed species. The sample was then degassed at room temperature for 5 min. The instrument performed nitrogen adsorption tests at 77 K. The SA was measured in units of m by obtaining the nitrogen adsorption / desorption isotherm. 2 The total specific surface area of ​​the sample in g was derived.

[0048] E) Particle size distribution (PSD) analysis PSD was measured using a Malvern Mastersizer 3000 with a Hydro MV wet dispersion unit after dispersing sample particles in aqueous media. Sufficient ultrasonic irradiation and agitation were applied and appropriate surfactants were introduced to improve the dispersion of metal hydroxide powders. The percentile values ​​D10, D50, and D90 are the particle size values ​​at 10%, 50%, and 90% of the cumulative distribution, respectively. The span value for hydroxides is (D90-D10) / D50.

[0049] F) Metal content analysis The metal content of the hydroxides was measured by inductively coupled plasma-optical emission spectroscopy (ICP-OES) using an Agilent ICP 720-OES instrument. One gram of powder sample from each example was dissolved in 50 mL of high-purity hydrochloric acid in an Erlenmeyer flask. The flask was covered with a watch glass and heated on a hot plate at 380 °C until the sample was completely dissolved. After cooling to room temperature, the solution and the Erlenmeyer flask's rinse water were transferred to a 250 mL volumetric flask. The volumetric flask was then filled to the 250 mL mark with deionized (DI) water, followed by thorough homogenization. An appropriate amount of the solution was pipetted and transferred to a 250 mL volumetric flask for a second dilution. The volumetric flask was then filled to the 250 mL mark with the internal standard and 10% hydrochloric acid, followed by homogenization. Finally, this solution was used for ICP-OES measurement. The contents of metals such as Ni, Mn, and Co are expressed as mol% of the total metal content in the measured hydroxide.

[0050] G) Void area analysis The void areas of the shell and core of the particles are calculated using ImageJ software (ImageJ 1.52a, US National Institutes of Health) according to the following steps.

[0051] Step 1) Open a file containing a well-contrasted SEM image of the positive electrode active material at 20,000x magnification. Figure 2a shows the SEM image of EX1. Step 2) Set the scale according to the SEM magnification. Step 3) Under "Select a measurement," check the box for "Area." Step 4) Select the polygon tool, select the outer edge of the particle shell, and then click "Analyze" - "Measure" to obtain the area (A1) of the entire particle. The equivalent radius (R1) of the particle is calculated by the following equation:

number

number

[0052] The void area of ​​the shell and core is calculated as follows:

[0053]

number

[0054] Example 1 An aqueous slurry of metal hydroxide was prepared according to the following process.

[0055] 0.75 L of DI water, 11 mL of 220 g / L NH3(aq), and Ni with a D50 of 1.2 μm 0.94 Mn 0.03 Co 0.03 The starting solution was prepared by adding 1000 mL of a 150 g / L aqueous slurry containing (OH)2 seed particles to a 3.6 L reactor and adjusting the temperature in the reactor to 85 °C, which was maintained throughout the process.

[0056] Next, a 120 g / L metal sulfate solution containing Ni, Mn, and Co (in a stoichiometric molar ratio of 94:3:3 Ni:Mn:Co), 55 g / L NH3(aq) and 220 g / L NaOH solution was heated to approximately 33 kW / m 3 The precipitation reaction was carried out by adding the metal sulfate solution while mixing at a stirring power of 182 mL / h. The feed rate of the metal sulfate solution was steadily increased from 182 mL / h to 900 mL / h throughout the precipitation. During the reaction, the feed rate of the NaOH solution was adjusted so that the pH value of the reaction mixture in the reactor was maintained constant at 10.5 ± 0.2, and the feed rate of NH3(aq) was adjusted so that the NH3(aq) concentration in the reaction mixture was maintained constant at 1.5 g / L at the start and increased to 5 g / L at the end. Reactor samples of the reaction mixture were taken every two hours, and the D50 was measured therefrom. The reaction was stopped when the D50 of the reactor sample reached the target value of approximately 3.5 μm. The process lasted for 16 hours. A portion of the liquid fraction of the reaction mixture was pumped out of the reactor during the process using an external concentrator. The solids content of the reaction mixture, which was an aqueous slurry containing hydroxide particles in the reactor, constantly increased and reached approximately 400 g / L at the end of the process.

[0057] The slurry was then filtered and washed with 220 g / L NaOH solution and DI water at 60° C. The filter cake was dried in an oven at 120° C. for 12 hours to obtain the dried product EX1.

[0058] Some of the properties of the dry powder hydroxide EX1 obtained in Example 1 are shown in Table 1.

[0059] Example 2 An aqueous slurry of metal hydroxide was prepared according to the following process.

[0060] 20 mL of 220 g / L NH3(aq) and Ni with a D50 of 1.3 μm 0.885 Mn 0.045 Co 0.07 The starting solution was prepared by adding 3000 mL of a 110 g / L aqueous slurry containing (OH)2 seed particles to a 3.6 L reactor and adjusting the temperature in the reactor to 85 °C, which was maintained throughout the process.

[0061] Next, a 120 g / L metal sulfate solution containing Ni, Mn, and Co (in a stoichiometric molar ratio of Ni:Mn:Co of 88.5:4.5:7), 55 g / L NH3(aq) and 220 g / L NaOH solution was added at approximately 33 kW / m 3The precipitation reaction was carried out by adding the metal sulfate solution while mixing at a stirring power of 1000 rpm. The feed rate of the metal sulfate solution was 180 mL / h for the first 4 hours, then increased to 500 mL / h for the next 8 hours, and then to 540 mL / h for the remainder of the precipitation. During the reaction, the feed rate of the NaOH solution was adjusted so that the pH value of the reaction mixture in the reactor was approximately 11.7 (at 20 °C) for the first 12 hours, then approximately 11.0 for the next 9 hours, and 10.5 for the remainder of the precipitation. The feed rate of the NH3(aq) was adjusted so that the g / l content of NH3 in the reactor was maintained at 1.5 g / l at the start and increased to 5 g / l at the end. Reactor samples of the reaction mixture were taken every 2 hours, and the D50 was measured from them. The reaction was stopped when the D50 of the reactor sample reached the target value of approximately 3.5 μm. The process duration was 32 hours. A portion of the liquid fraction of the reaction mixture was pumped out of the reactor during the process by using an external concentrator, and the solid content of the reaction mixture, which was an aqueous slurry containing hydroxide particles in the reactor, constantly increased and was about 800 g / L at the end of the process.

[0062] Some of the properties of the dry powder hydroxide EX2 obtained in EX2 are shown in Table 1.

[0063] The comparative dry hydroxide product CEX1 used in Example C is also shown in Table 1.

[0064] [Table 1]

[0065] Preparation of cathode active material Example C The positive electrode active material (EX1-C1) was prepared according to the following steps.

[0066] Step 1) Mixing: EX1 was mixed with ZrO2 and LiOH in an industrial blender to obtain a mixture with 0.125 mol% Zr and a lithium to metal (Ni, Mn, and Co) ratio of 1.00. Step 2) Heating: The mixture from step 1) was heated under flowing oxygen at a first temperature of 760°C for 10 hours and then at a second temperature of 710°C for 10 hours. Step 3) After treatment: The heated powder from step 2) was ground by a grinder for 30 seconds and then sieved to obtain a positive electrode active material designated as EX1-C1.

[0067] Additional positive electrode active materials (EX1-C2 and EX1-C3) were prepared according to the same method as EX1-C1, except that the first temperature in step 2) was 790°C for EX1-C2 and 820°C for EX1-C3, respectively.

[0068] Comparative example C A comparative positive electrode active material (CEX1-C1) was prepared according to the following steps.

[0069] Step 1) Mixing: CEX1 was mixed with ZrO2 and LiOH in an industrial blender to obtain a mixture with 0.125 mol% Zr and a lithium to metal (Ni, Mn, and Co) ratio of 1.00. Step 2) Heating: The mixture from step 1) was heated under flowing oxygen at a first temperature of 760°C for 10 hours and then at a second temperature of 710°C for 10 hours. Step 3) After treatment: The heated powder from step 2) was ground by a grinder for 30 seconds and then sieved to obtain a comparative cathode active material designated as CEX1-C1.

[0070] Further comparative positive electrode active materials (CEX1-C2 and CEX1-C3) were prepared according to the same method as CEX1-C1, except that the first temperature in step 2) was 790°C for CEX1-C2 and 820°C for CEX1-C3, respectively.

[0071] FIG. 3 shows the average size D50 of the positive electrode active material of Example C and the positive electrode active material of Comparative Example C after 30 seconds of low-energy milling. Low-energy milling is a common practice to break down powders that have hardened after heating for further processing. It is observed that the positive electrode active material obtained from EX1 achieves a smaller D50 after milling compared to the positive electrode active material of CEX1.

[0072] Figure 4 shows the D50 values ​​of EX1-C3 and CEX1-C3 after bead milling in water for 0, 3, 6, and 13 hours. Prior to bead milling, the cathode active material was continuously low-energy milled for 30 minutes. Bead milling is performed to obtain cathode active material containing single-crystal particles. Consistent with the observations from the low-energy milling in Figure 4, EX1-C3 achieves a smaller D50 value compared to CEX1-C3 after the same bead milling period. It can be concluded that the cathode active material obtained from CEX1 requires higher energy to achieve the same D50 value as the cathode active material obtained from EX1. The low energy requirement for EX1 is due to the metal hydroxide structure of the present invention. The porous shell structure, exhibiting a shell void area percentage of at least 20%, minimizes the contact area between particles and avoids agglomeration.

Claims

1. A powder material of hydroxide or oxyhydroxide of one or more metal elements for preparing a positive electrode active material for a battery, wherein the one or more metal elements include at least one of Ni, Co, and Mn, and the powder material includes particles having a core and a shell surrounding the core, and the core has a total area (A ｃ ), and the shell has a total area (A ｓ ) and the shell has a total area (A ｓ ) based on a void area percentage of at least 20% and up to 99%, and the powder material has a void area percentage of at least 7.0 m ２ / g of BET specific surface area.

2. The core has a total area (A ｃ 2. The powder material of claim 1, having a void area percentage of at most 10%, more preferably at most 5%, and even more preferably at most 1%, based on the powder area percentage (based on the total particle size).

3. 2. The powder material of claim 1, wherein the shell has a void area percentage of at least 25%, preferably at least 30%, more preferably at least 50%.

4. 2. The powder material of claim 1, wherein the particles have an average radius of the particles (R1), an average radius of the core (R2), and a ratio (R) between the average radius of the particles and the average radius of the core (R1 / R2), wherein R≧1.00, preferably R≧1.50, more preferably R≧2.00, and both R1 and R2 are obtained by taking an average of radius measurements of a representative number of particles by SEM image analysis.

5. 5. The powder material according to claim 4, wherein R≦10 or R≦5 or R≦3.

6. The powder material is at least 15.0 m ２ / g, preferably at least 20.0 m ２ 10. The powder material of claim 1, having a BET specific surface area of ​​0.1g / g.

7. 2. The powder material of claim 1, wherein the particles have a median particle size D50, determined by laser diffraction, of at least 2.0 μm and at most 10 μm, preferably at least 2.5 μm and at most 8 μm, more preferably at least 3 μm and at most 5 μm.

8. 2. The powder material according to claim 1, wherein the percentage ratio between (R1-R2) and R1 is at most 90.0%, preferably at most 80.0%, more preferably at most 60%.

9. Ni with a content x, where x≧5.0 mol%; Mn having a content z, where 0≦y≦85.0 mol%, and Co having a content y of Co, where 0≦z≦30.0 mol%; one or more additional elements in a content r from the list Al, B, Ba, Ca, Ce, Cr, Fe, La, Mg, Mo, Nb, Si, Sr, Ti, Y, V, W, Zn, and Zr, where 0≦r≦5.0 mol%, 2. The powder material according to claim 1, wherein x, y, z, and r are contents expressed in mol% relative to the total molar content of the powder material, and x + y + z + r = 100.0 mol%.

10. 10. The powder material according to claim 9, wherein x≧60 mol%, or x≧70 mol%, or x≧80 mol%, or x≧90 mol%, and / or y≧20 mol%, and / or z≦25 mol%.

11. 2. The powder material according to claim 1, wherein the span value (D90-D10) / D50 is at most 1.00, preferably at most 0.80, more preferably at most 0.50, even more preferably at most 0.

30.

12. The powder material of claim 1 , wherein the particles are secondary particles comprising a plurality of primary particles.

13. A method for producing a positive electrode active material, comprising: mixing a powder material of hydroxide or oxyhydroxide of one or more metal elements according to any one of claims 1 to 12, a lithium source, and an optional dopant source to obtain a mixture; and heating the mixture at a temperature of 650°C to 1000°C in an oxidizing atmosphere to obtain the positive electrode active material; and optionally, The method further comprises a step of heat treatment before mixing, wherein the powder material is heated at a temperature between 105°C and 750°C.

14. A method for producing the powder material according to any one of claims 1 to 12, comprising the steps of: providing an initiation solution comprising an aqueous slurry of seed particles to a reactor; feeding a stream of metal salt solution containing one or more metal elements into the reactor for a period of time (T1-T2); During the period T1 to T2, mixing the starting solution, the metal salt solution, and an aqueous solution containing one or more alkali hydroxides, thereby precipitating hydroxides of one or more metal elements and forming an aqueous slurry containing hydroxides of the one or more metal elements; Here, during the period T1 to T2, in the reactor, a pH value which may vary or be kept constant within the range of 10.0 to 11.9, for example 10.0 to 11.0, preferably 10.2 to 10.7, said pH value being measured on a sample of the aqueous slurry at 20°C; NH 3 of 1.0 g / l or more, preferably 15.0 g / l or less, preferably 1.5 g / l or more and 5 g / l or less ３ maintain a concentration of After the end of time period T2, the aqueous slurry in the reactor is further processed by separating a solid fraction from a liquid fraction and drying the solid fraction to obtain the powder material.

15. During the period T1 to T2, in the reactor, 15. The method of claim 14, wherein a temperature of at least 60°C, preferably at least 70°C, is maintained.

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