Cathode material, its manufacturing method, and applications

Abstract

A positive electrode material, a method for manufacturing the same, and its applications are described, wherein the value of Dv50 of the positive electrode material is α, the unit is μm, the lithium-rich content of the positive electrode material is γ, the average porosity of the positive electrode material is β% as a percentage, and α, β, and γ satisfy δ = β - [2α + 75γ] / 3, with 0 ≤ δ ≤ 4.0. By limiting the relationship between Dv50, average porosity, and lithium-rich content of the positive electrode material, lithium-ion batteries manufactured with this positive electrode material can combine excellent specific capacity, energy density, rate performance, and cycle performance, and can maintain excellent electrochemical performance, especially at high voltages.

Description

[Technical Field]

[0001] This application relates to positive electrode materials, their manufacturing methods, and applications, and belongs to the field of lithium-ion battery technology. [Background technology]

[0002] The performance of the cathode material directly determines the performance of the lithium-ion battery. The specific capacity, cycle performance, and rate characteristics of the cathode material directly affect the energy density, lifespan, and fast-charging performance of the lithium-ion battery. Lithium-rich cathode materials (e.g., layered lithium-rich cathode material Li[Li 1-x-y-z Ni x Co y Mn z Although lithium-rich cathode materials (O2) are attracting attention due to their high specific capacity and cost advantages, their rate performance is inferior to ternary cathode materials. Against the backdrop of increasingly high industrial demands for rapid charging, improving the rate performance of lithium-rich cathode materials has become a research focus in this field.

[0003] The high specific capacity of lithium-rich cathode materials is primarily due to the reversible redox process of doped anions and the localized electron vacancies formed on oxygen atoms. In actual use, to avoid a series of problems caused by extremely high voltages, appropriately reducing the operating voltage window can provide excellent cycle stability at slightly lower capacity levels, but the rate performance remains insufficient, failing to meet the requirements of high power density and limiting rapid charging performance. This is because anionic redox has a greater impact on the stability of the crystal structure and its response is slower compared to cationic redox, while layered ternary systems... material Dynamic performance Compared , Layered ternary materials are Capacity is provided solely through cationic oxidation-reduction. deathCompared to ternary cathode materials, lithium-rich cathode materials have problems such as a high unit cell volume change rate, severe lattice distortion, and limited dynamic performance. As a result, lithium ion movement becomes difficult, polarization increases, voltage delay occurs, and the efficiency of charge and discharge energy of the cathode material decreases, making it impossible to achieve high rate performance.

[0004] At present, the goal is often to improve the rate performance of lithium-rich cathode materials by adjusting the structure, particle size, and particle size distribution of secondary particles, thereby improving the dispersibility of lithium-rich cathode materials in cathode slurries and shortening the lithium ion transmission distance. Examples include patent documents CN106340638A, US9478808B2, and US10978709B2. While the above methods have provided several directions for improving rate performance, there is a need to further improve the rate performance of lithium-rich cathode materials. [Overview of the project] [Problems that the invention aims to solve]

[0005] The positive electrode material according to this invention limits the relationship between the Dv50 of the positive electrode material, the average porosity, and the lithium-rich content. As a result, lithium-ion batteries manufactured with this positive electrode material possess excellent specific capacity, energy density, rate performance, and cycle performance, and can maintain particularly excellent electrochemical performance even at high voltages.

[0006] This invention further provides a method for manufacturing a positive electrode material, the positive electrode material manufactured by this method being applied to a lithium-ion battery, the lithium-ion battery having excellent specific capacity, rate performance and cycle performance.

[0007] The present invention further provides a positive electrode plate which includes the above-mentioned positive electrode material, and a lithium-ion battery assembled with this positive electrode plate possesses excellent specific capacity, energy density, rate performance, and cycle performance.

[0008] The present application further provides a lithium-ion battery. Since the lithium-ion battery includes the above positive electrode plate, the lithium-ion battery assembled with the positive electrode plate has excellent specific capacity, rate performance, and cycle performance.

Means for Solving the Problems

[0009] In a first aspect, the present application provides a positive electrode material. The value of Dv50 of the positive electrode material is α, with the unit of μm. The lithium-rich amount of the positive electrode material is γ. The average porosity of the positive electrode material is β% in percentage. α, β, and γ satisfy δ = β - [2α + 75γ] / 3, and 0 ≤ δ ≤ 4.0.

[0010] According to the positive electrode material as described above, the positive electrode material includes secondary particles and a coating layer covering at least a part of the surface of the secondary particles.

[0011] According to the positive electrode material as described above, the total molar amount of the elements distributed in the cation form in the secondary particles is A, and the total molar amount of the elements distributed in the anion form in the secondary particles is B. A and B satisfy 0.985 ≤ A / B ≤ 1.0.

[0012] According to the positive electrode material as described above, the secondary particles include a doped metal element distributed in the cation form and a doped non-metal element distributed in the anion form. The molar ratio of the doped metal element to the other elements distributed in the cation form other than lithium ions in the secondary particles is 5% or less, and / or The molar ratio of the doped non-metal element to the total of the elements distributed in the anion form in the secondary particles is 10% or less.

[0013] According to the positive electrode material as described above, the chemical formula of the secondary particles is Li 1+x-2y M z M’ 1-x-z O 2-y-t R t where M is Ni a Co b Mn cLet a+b+c=1.0, 0≦b≦0.10, a≧2b, 1.5≦c / (a+b)≦3.0, x=(ca) / (2+ca), 0.985≦(2-2y) / (2-y)≦1.0, (19-19x) / 20≦z≦(1-x), 0≦t≦(2-y) / 10. M' is a doped metallic element, and R is a doped nonmetallic element.

[0014] According to the positive electrode material described above, M' includes at least one of Cr, Mo, W, Ta, Nb, P, Sb, Te, Hf, Ce, Ti, Zr, Sn, La, Al, Mg, Fe, K, Na, and / or R includes at least one of F and S.

[0015] According to the positive electrode material described above, the Dv50 of the positive electrode material is 2.5 to 10.6 μm, and / or The minimum particle size Dv of the positive electrode material min is 0.6 μm or larger, and / or The aforementioned secondary particles are formed by the aggregation of primary particles, and the average thickness of the primary particles is 80 to 250 nm, and / or The specific surface area of ​​the secondary particles is 0.5 m². 2 / g or more 1.5m 2 / g or less, and / or β is 7-13, and / or The lithium-rich amount γ is between 0.09 and 0.21.

[0016] According to the positive electrode material described above, the ratio of the molar amount of the coating layer material to the total molar amount of the positive electrode material is (0.2~1.0):100, and / or, The coating layer material is a phosphate and / or an inert oxide, wherein the phosphate includes at least one of AlPO4 and LaPO4, and the inert oxide includes at least one of Al2O3, TiO2, ZrO2, and La2O3.

[0017] In a second aspect, the present application provides a method for manufacturing a positive electrode material as described in the first aspect, the method being: The process involves a step of mixing a metal salt solution, an alkaline solution, and an oxidizing agent to obtain a reaction system, and then precipitating the reaction system to obtain a precursor, wherein the oxidizing agent contains sodium hypochlorite, and the concentration of the oxidizing agent in the reaction system is 0.2 to 2 g / L. The method includes the steps of: mixing a precursor, a lithium salt, and a pore-forming agent to obtain a first mixed material; and performing a first sintering treatment on the first mixed material to obtain a positive electrode material.

[0018] According to the manufacturing method described above, the first mixture further contains a doped element-containing compound, and / or The method further includes the steps of: mixing the product of the first sintering process with a coating layer material after the first sintering process to obtain a second mixture; and performing a second sintering process on the second mixture to obtain a positive electrode material.

[0019] According to the manufacturing method described above, the conditions for the precipitation reaction are a stirring speed of 700-800 rpm, a temperature of 50-70°C, and a pH of 9.5-11.5. The temperature of the first sintering process is 800-950°C, and the holding time is 10-15 hours. 、 and / or, The coating layer material contains an inert oxide, the temperature of the second sintering treatment is 500-800°C, the heating rate is 5-10°C / min, the time is 5-10h, and / or The coating layer material contains phosphate, the temperature of the second sintering treatment is 700-900°C, the heating rate is 5-10°C / min, and the duration is 5-10 hours.

[0020] According to the manufacturing method described above, the mass of the pore-forming agent is 0.1 to 1.0 wt% of the mass of the precursor. The porosity-forming agent comprises at least one of ammonium carbonate, ammonium sulfate, ammonium persulfate, ammonium nitrate, and ammonium chloride.

[0021] In a third aspect, the present application provides a positive electrode plate comprising a positive electrode material manufactured by the positive electrode material described in the first aspect or the manufacturing method described in the second aspect.

[0022] According to the positive electrode plate described above, the positive electrode plate includes a current collector and a positive electrode active material layer on at least one functional surface of the current collector. The positive electrode active material layer includes the positive electrode material, a conductive agent, and a binder. The mass of the positive electrode material accounts for 94 wt% or more of the total mass of the positive electrode active material layer.

[0023] In a fourth aspect, the present application provides a lithium-ion battery, the lithium-ion battery comprising a positive electrode plate according to the third aspect.

[0024] According to the lithium-ion battery described above, the lithium-ion battery further comprises a separator, a negative electrode plate, and an electrolyte. The negative electrode plate includes at least one of lithium foil, graphite, and silicon carbon negative electrode.

[0025] According to the lithium-ion battery described above, after 200 cycles under charge-discharge conditions of 2.5 to 4.5V and 0.5C / 1.0C, the increase rate of the average cross-sectional porosity of the positive electrode material on the positive electrode plate is less than 2%.

[0026] In a fifth aspect, the present application provides a power consumption device including a lithium-ion battery as described in the fourth aspect, preferably the power consumption device including an electric vehicle, a manned electric aircraft, and an unmanned aircraft. [Effects of the Invention]

[0027] Implementing this invention will have at least the following beneficial effects. The positive electrode material for lithium-ion batteries according to this invention controls the Dv50 value α, lithium-rich content γ, and average porosity β% of the positive electrode material so that δ = β - [2α + 75γ] / 3 is satisfied and 0 ≤ δ ≤ 4.0, thereby ensuring that the average particle size and lithium-rich content of the positive electrode material match the average porosity, and thereby maximizing the specific capacity, rate performance, and cycle performance of lithium-ion batteries manufactured with this positive electrode material, especially the electrochemical performance under high voltage conditions.

[0028] The method for manufacturing a positive electrode material according to this invention is advantageous for adjusting the Dv50 value and average porosity of the positive electrode material by introducing an oxidizing agent and a porosity-forming agent and limiting the concentration of the oxidizing agent. A positive electrode material satisfying the relational equation δ = β - [2α + 75γ] / 3 is produced, and when this positive electrode material is applied to a lithium-ion battery, the lithium-ion battery exhibits excellent specific capacity, rate performance, and cycle performance. [Brief explanation of the drawing]

[0029] [Figure 1] This is a first-magnification cross-sectional SEM view of the positive electrode material in Example 1. [Figure 2] This is a second-magnification cross-sectional SEM view of the positive electrode material in Example 1. [Figure 3] These are cross-sectional and region division diagrams showing the porosity measurement of a single secondary particle of the cathode material in Example 1. [Figure 4] This is a cross-sectional SEM view of the cathode material in Comparative Example 1 at the first magnification. [Figure 5] This is a cross-sectional SEM view of the cathode material in Comparative Example 1 at a second magnification. [Figure 6] This shows the porosity measurement cross-section and region division diagram of a single secondary particle of the cathode material in Comparative Example 1. [Figure 7] This is a first-magnification cross-sectional SEM view of the cathode material in Example 2. [Figure 8] This is a second-magnification cross-sectional SEM view of the cathode material in Example 2. [Figure 9] This shows the porosity measurement cross-section and region division diagram of a single secondary particle of the cathode material in Example 2. [Figure 10] This is a cross-sectional SEM view of the cathode material in Comparative Example 2 at the first magnification. [Figure 11] This is a cross-sectional SEM view of the cathode material in Comparative Example 2 at a second magnification. [Figure 12] This shows the porosity measurement cross-section and region division diagram of a single secondary particle of the cathode material in Comparative Example 2. [Figure 13] This is a cross-sectional SEM view of the cathode material in Comparative Example 3 at the first magnification. [Figure 14] This is a cross-sectional SEM view of the cathode material in Comparative Example 3 at a second magnification. [Figure 15] This shows the porosity measurement cross-section and region division diagram of a single secondary particle of the cathode material in Comparative Example 3. [Figure 16] This is a first-magnification cross-sectional SEM view of the positive electrode plate after 200 cycles of the entire battery assembled with the positive electrode material in Example 2. [Figure 17] This is a second-magnification cross-sectional SEM view of the positive electrode plate after 200 cycles of the entire battery assembled with the positive electrode material in Example 2. [Figure 18] These are cross-sectional and region division diagrams showing the porosity measurement of a single secondary particle in the cathode material after 200 cycles of the entire battery assembled with the cathode material in Example 2. [Figure 19] This is a first-magnification cross-sectional SEM view of the positive electrode plate of a battery assembled with the positive electrode material of Comparative Example 3 after 200 cycles. [Figure 20] This is a second-magnification cross-sectional SEM view of the positive electrode plate of a battery assembled with the positive electrode material of Comparative Example 3 after 200 cycles. [Figure 21] These are cross-sectional and region division diagrams showing the porosity measurement of a single secondary particle in the cathode material after 200 cycles of the entire battery assembled with the cathode material of Comparative Example 3. [Modes for carrying out the invention]

[0030] To further clarify the purpose, technical solution, and advantages of this application, the technical solution will be clearly and completely described below using embodiments of this application. Naturally, the embodiments described are not all embodiments of this application, but only a selection of them. All other embodiments obtained by those skilled in the art without creative work based on the embodiments of this application are also covered by this application.

[0031] In the first aspect, the present invention provides a positive electrode material, wherein the Dv50 value of the positive electrode material is α, the unit is μm, the lithium-rich amount of the positive electrode material is γ, the average porosity of the positive electrode material is β% as a percentage, and α, β, and γ satisfy δ = β - [2α + 75γ] / 3, and 0 ≤ δ ≤ 4.0.

[0032] In this application, Dv50 of the positive electrode material refers to the particle size where the volume distribution of the particles constituting the positive electrode material corresponds to 50%, and may also be called the average particle size. The lithium-rich amount is for positive electrode materials where the lithium:transition metal ratio > 1; that is, for positive electrode materials with a specific chemical formula, the numerical value where the subscript of lithium exceeds 1 is the lithium-rich amount. The average porosity of the positive electrode material is the percentage of the volume of internal pores of the particles constituting the positive electrode material relative to the volume of the positive electrode material. If the positive electrode material consists of secondary particles, the average porosity of the positive electrode material is measured by calculating the porosity of a single secondary particle of the positive electrode material, selecting 20 or more secondary particles in the positive electrode material, measuring their porosity, and calculating their average value to obtain the average porosity of the positive electrode material.

[0033] This application does not limit the specific types of cathode materials, but lithium-rich cathode materials are an example. In lithium-ion batteries manufactured with lithium-rich cathode materials, a portion of the battery's specific capacity is provided by an anion oxidation-reduction process.

[0034] The inventors' research has confirmed that the average porosity of the cathode material has a significant impact on the rate performance of the cathode material (especially lithium-rich cathode materials), and that an appropriate average porosity is a crucial factor for lithium-rich materials to exhibit excellent rate performance, and that the average porosity should be controlled within a reasonable range. If the average porosity of the cathode material is too high, the structural strength and compressive density of the cathode material decrease. Furthermore, in the early stages of the cathode material cycle, if the electrolyte does not completely penetrate into the interior of the cathode material, excessively high porosity tends to form localized "islands" inside the cathode material, which is detrimental to power performance and capacity. Moreover, as the cycle progresses, more electrolyte comes into contact with the cathode material, resulting in serious side reactions, decreased battery stability, increased gas generation, and disadvantages for industrial application. If the average porosity of the cathode material is too low, the meandering of the lithium ion transfer pathway is high, the electrolyte penetration effect is poor, and it seriously affects the rate performance.

[0035] Conventional ternary cathode materials have excellent rate performance, eliminating the need to adjust the porosity of the cathode material according to particle size and transition metal ratio. However, considering particle strength and volumetric energy density, it is usually necessary to control the porosity of secondary particles in ternary cathode materials to within 3%. In the relational equation δ=β-[2α+75γ] / 3 of this application, the average porosity of the cathode material shows a positive correlation with the lithium-rich content and the Dv50 value. That is, the higher the lithium-rich content of the cathode material, the higher the corresponding average porosity of the cathode material, and the higher the Dv50 of the cathode material, the higher the corresponding average porosity of the cathode material.

[0036] Furthermore, with conventional technology, there are significant differences in the porosity of lithium-rich cathode materials, making it difficult to comprehensively consider and design power characteristics (rate performance), capacity, structural stability, and energy density. This results in situations where capacity is high but porosity is too high, leading to no particular problem with power performance but failing to meet the standard for compressive density, or conversely, where compressive density is high and porosity is low, but capacity does not meet the standard and power performance is poor. On the other hand, this invention can improve the rate performance, capacity, structural stability, and energy density of batteries containing the above cathode material by limiting the relationship between the average porosity value, the lithium-rich content, and the Dv50 value. The reason for this is as follows.

[0037] On the other hand, the lithium-rich content in the cathode material is directly correlated with the nickel-manganese transition metal element blending ratio in the cathode material. Therefore, the lithium-rich content in the cathode material can indicate the ratio of the lithium-rich phase, i.e., the ratio of anions that provide capacity through oxidation-reduction in the cathode material. The higher the lithium-rich content, the higher the contribution of capacity due to anion oxidation-reduction in the cathode material. Correspondingly, the range of variation in the unit cell parameters increases, and the dynamic performance tends to decrease. In this case, the average porosity value of the cathode material limited by this application is positively correlated with the lithium-rich content. In other words, the cathode material of this application has a large average porosity value so that the cathode material is in sufficient contact with the electrolyte, the lithium ion transfer path is optimized, the loss of dynamic performance of the cathode material due to the intensification of anion oxidation-reduction is offset, and dynamic performance is maintained at a high level. This ensures the energy density of the cathode plate and the specific capacity and rate performance of the lithium-ion battery.

[0038] On the other hand, the Dv50 of the positive electrode material directly affects the dynamic performance of the positive electrode material. The larger the Dv50, the longer the lithium ion transfer distance. Furthermore, during the charge and discharge process, the volume contraction and expansion of the particles in the positive electrode material cause the particles to be compressed against each other, leading to a tendency to form greater internal stress and more grain boundaries, which is unfavorable for the continuous movement of lithium ions. In this case, the average porosity value and the Dv50 value of the positive electrode material limited by this application exhibit the positive correlation described above. That is, the positive electrode material according to this application has a relatively large average porosity value, which reduces internal stress, avoids fracture of secondary particles, protects lithium ions from difficulty in movement due to increased stress, and can offset the increase in polarization of the positive electrode material due to the increase in lithium ion transfer distance. This ensures the cycle performance and rate performance of the lithium-ion battery.

[0039] When the positive electrode material according to this application is a layered lithium-rich positive electrode material, the positive electrode material has a layered structure, and in some embodiments, the positive electrode material includes secondary particles and a coating layer covering at least a portion of the surface of the secondary particles. The secondary particles are obtained by aggregating a plurality of primary particles, and the secondary particles have a spherical or substantially spherical shape, for example, an ellipsoid shape. The coating layer reduces side reactions between the positive electrode material and the electrolyte, suppresses decay of the surface structure of the positive electrode material, dissolution of transition metals in the secondary particles, and deactivation of the electrolyte, thereby improving the stability of the positive electrode material and ensuring the stability of the positive electrode material, especially in high-voltage systems.

[0040] In conventional technology, the ratio of the total anions to the total cations in ternary cathode materials is 1. However, in the case of lithium-rich cathode materials, the surface structure may change during the coating process. Due to the corrosive action of some acidic substances, Li2O may be desorbed from the surface of secondary particles, causing the ratio of the total anions to the total cations to fall below 1. However, if the desorption of Li2O is excessive, the structure of the cathode material will collapse, and the battery capacity and stability will decrease significantly. For this reason, in some examples, the total molar amount of elements distributed in cationic form in secondary particles is A, and the total molar amount of elements distributed in anionic form in secondary particles is B, and A and B satisfy 0.985 ≤ A / B ≤ 1.0, that is, the desorption ratio of lithium ions is limited to 6% or less, thereby ensuring that the coating layer improves the interfacial stability of the cathode material without impairing the stability of the bulk structure of the secondary particles.

[0041] Taking layered lithium-rich cathode materials as an example, by doping them with other metal elements distributed in cationic form, and nonmetal elements distributed in cationic form, in addition to Li, Ni, Co, and Mn, diverse performance needs for industrialization can be met. In some examples, secondary particles contain doped metal elements distributed in cationic form and doped nonmetal elements distributed in anionic form, and the molar ratio of doped metal elements to other elements distributed in cationic form other than lithium ions in the secondary particles is 5% or less. The other elements distributed in cationic form other than lithium ions in the secondary particles include Ni, Co, Mn, and doped metal elements, in which case the molar amount of doped metal elements / total molar amount of Ni, Co, Mn, and doped metal elements × 100% ≤ 5%. Subsequently, taking layered lithium-rich cathode materials as an example, in some examples, the molar ratio of doped nonmetal elements to the total of elements distributed in anionic form in the secondary particles is 10% or less. The total amount of elements distributed in anionic form within secondary particles includes O and doped nonmetallic elements, where the molar amount of doped nonmetallic elements / total molar amount of O and doped nonmetallic elements × 100% ≤ 10%. By limiting the amounts of doped metallic and doped nonmetallic elements, it is possible to improve specific performance characteristics of the cathode material to different degrees, as well as avoid imbalances in product performance due to excessive doping.

[0042] In this application, the chemical formula of the secondary particle is Li 1+x-2y M z M' 1-x-z O 2-y-t R t And M is Ni a Co b Mn c Let a+b+c=1.0, 0≦b≦0.10, a≧2b, 1.5≦c / (a+b)≦3.0, x=(ca) / (2+ca), 0.985≦(2-2y) / (2-y)≦1.0, (19-19x) / 20≦z≦(1-x), 0≦t≦(2-y) / 10, where M' is a doped metallic element and R is a doped nonmetallic element.

[0043] By limiting it to 0.985≦(2-2y) / (2-y)≦1.0, it is advantageous to ensure that the ratio of the total molar amount A of elements distributed in cationic form to the total molar amount B of elements distributed in anionic form in the secondary particles satisfies 0.985≦A / B≦1.0. By limiting it to (19-19x) / 20≦z≦(1-x), it is advantageous to ensure that the molar ratio of doped metal elements to other elements distributed in cationic form other than lithium ions in the secondary particles is 5% or less. By limiting it to 0≦t≦(2-y) / 10, it is advantageous to ensure that the molar amount of doped nonmetal elements / O and the total molar amount of doped nonmetal elements × 100%≦10%.

[0044] In the chemical formula of the secondary particles described above, the lithium-rich amount γ of the positive electrode material may be x-2y. By limiting x=(ca) / (2+ca), the lithium-rich amount directly correlates with the molar proportion of nickel-manganese elements. In other words, the lithium content of the positive electrode material directly correlates with the proportion of transition metal elements, and an appropriate lithium content ensures that the material exhibits its electrochemical performance to the maximum. Specifically, by adjusting the lithium content according to the relative molar amount of nickel-manganese elements, the valence of all elements distributed in cation form is stabilized, and in particular, the valence state of Mn elements is brought closer to +4, thereby minimizing the influence of the Jahn-Teller effect on structural stability, and thus the performance of the positive electrode material is within the optimal range. If the lithium content is too high, the particles of the positive electrode material grow excessively, the activity of Li2MnO3 in the positive electrode material decreases severely, and the valence of nickel elements increases, resulting in decreased power performance and limited capacity. On the other hand, the cathode material according to the present invention satisfies the above relational expression, has a reasonable lithium-rich content, and can integrally maintain the rate performance, capacity output, and cycle stability of the cathode material at the maximum level.

[0045] The nickel content increases the energy density of lithium-ion batteries, the cobalt content stabilizes the layered structure of the cathode material, improving the cycle life and rate performance of the manufactured lithium-ion batteries while simultaneously reducing their impact on specific capacity, and the manganese content not only enhances the structural stability of the cathode material and the safety of the manufactured lithium-ion batteries, but also reduces the material cost of the lithium-ion batteries while simultaneously decreasing their impact on specific capacity. Therefore, by selecting the composition ratio of nickel, cobalt, and manganese in the secondary particles of the cathode material, it is possible to achieve optimal energy density, cycle performance, and rate performance of lithium-ion batteries manufactured with that cathode material.

[0046] When 0≦b≦0.10 and a≧2b are satisfied, the molar ratio of nickel is greater than twice the molar ratio of cobalt, and the molar ratio of cobalt is 10% or less. While material costs can be reduced by controlling the proportion of cobalt, increasing the cobalt content relative to nickel slightly increases the capacity of the cathode material. At the same time, layered lithium-rich cathode materials have a higher upper limit of the operating voltage window than ternary cathode materials. Cobalt is the main cause of capacity improvement in layered lithium-rich cathode materials because it catalyzes and improves the activity of the lithium-rich phase. Therefore, as the cobalt content increases, the structural stability of the layered lithium-rich cathode material decreases slightly due to more advanced anionic redox, and similarly, the power performance also decreases slightly. While cobalt-free layered lithium-rich cathode materials do not exhibit inferior cycle stability compared to cobalt-containing layered lithium-rich cathode materials, the absence of cobalt's catalytic activation results in significant initial polarization of the cathode material. Li2MnO3 exhibits sustained activation in the early stages of the cycle, leading to a continuous increase in the overall capacity of the cathode material, which presents challenges in cell BMS design. However, this invention avoids this phenomenon by controlling the cobalt content, thereby reducing late-stage design costs. Consequently, the cathode material according to this invention effectively balances the aforementioned advantages and disadvantages. By limiting the proportion of transition metals, it balances important indicators such as cost, rate performance, capacity output, and structural stability of the cathode material, ensuring superior overall performance and enabling this cathode material to better meet the performance requirements of industrial applications.

[0047] When 1.5 ≤ c / (a+b) ≤ 3.0 is satisfied, the molar proportion of manganese is 1.5 times that of nickel. cobalt By ensuring that the molar proportions of the elements are greater than or equal to the sum of the molar proportions of the elements, the cathode material has a lower watt-hour cost than other ternary cathode materials, while simultaneously reducing the molar amount of manganese by nickel. cobaltIt is possible to ensure that the sum of the molar amounts of the elements is less than or equal to three times the upper limit of the proportion of lithium-rich phase in the positive electrode material. In actual application, capacity is not proportional to the proportion of lithium-rich phase. When the proportion of lithium-rich phase increases to a certain limit, and then increases further, the increase in capacity slows down significantly due to the increase in polarization of the material, and consequently, a phenomenon occurs where the capacity decreases in high-density systems. Furthermore, manganese is prone to disproportionation reactions during long cycle processes, dissolves in the electrolyte, moves to the negative electrode under the action of an electric field, and causes deactivation of the negative electrode. Also, if the molar proportion of manganese is too high, i.e., the proportion of lithium-rich phase is too high, the structural stability of the positive electrode material decreases, and batteries assembled with such a positive electrode material experience a rapid decay of cell energy, leading to the drawback of not being able to meet the needs of industrialization. For this reason, when 1.5 ≤ c / (a+b) ≤ 3.0 is satisfied, the battery system can achieve high cost performance.

[0048] The specific types of the doped metallic element M' and doped nonmetallic element R described above are not limited to this application and can be adjusted according to actual needs. For example, in some embodiments, M' includes at least one of Cr, Mo, W, Ta, Nb, P, Sb, Te, Hf, Ce, Ti, Zr, Sn, La, Al, Mg, Fe, K, and Na, and / or R includes at least one of F and S.

[0049] Specifically, the doped metal elements mentioned above are Cr 6+ Mo 6+ , W 6+ Ta 5+ Nb 5+ , P 5+ Sb 5+ Te 4+ , Hf 4+ Ce 4+ Ti 4+ , Zr 4+ Sn 4+ , La 3+ , Al 3+ Mg 2+ Fe 2+ , K + kaNa +It can be distributed in secondary particles in the form of F - S 2- It can be distributed to secondary particles in this form.

[0050] When the doped metal elements are Mo, W, Ta, Nb, and Sb, Mo 6+ , W 6+ Ta 5+ Nb 5+ Sb 5+ When distributed in the form of high-value cations, it is useful for adjusting the particle size of the primary particles of the cathode material. As the concentration of the doped element in the form of high-value cations increases, under the same sintering conditions, the smaller the particle size of the primary particles of the cathode material, the lower the internal stress, the better the capacity performance, the less likely secondary particle fragmentation will occur as the cycle progresses, and this contributes to improved cycle performance and safety performance. When the doped metal element is P, 5+ It tends to form phosphate roots on the subsurface layer (i.e., the surface of secondary particles) of the cathode material, which improves the stability of the anion framework and extends the service life of the cathode material. When the doped metal element is Cr, Te, Hf, Ti, Zr, Sn, La, Al, Mg, Fe, K, Na, Cr 6+ Te 4+ , Hf 4+ Ti 4+ , Zr 4+ Sn 4+ , La 3+ , Al 3+ Mg 2+ Fe 2+ , K + kaNa + This increases the stability of alkali metal layers (i.e., lithium layers) or transition metal layers (i.e., nickel-cobalt-manganese layers), suppresses irreversible cation migration, stabilizes the bulk structure, and when the doped nonmetallic element is F, then F - It has stronger electronegativity, forms stronger covalent bonds with cations, improves the structural stability of the cathode material, and when the doped nonmetal element is S, 2- Doping can stabilize the anion framework, S 2-To some extent, it functions as a buffer site for oxygen anion oxidation-reduction, increasing the reversibility of oxygen anion oxidation-reduction and contributing to improved capacity and rate performance.

[0051] In some examples, the Dv50 of the positive electrode material is 2.5 to 10.6 μm, and / or the minimum particle size Dv of the positive electrode material. min The particle size is 0.6 μm or larger. This suppresses the generation of fine particles in the positive electrode material, avoids serious interfacial side reactions and gas generation during cycling, and is advantageous for improving the cycle performance and safety performance of batteries assembled with this positive electrode plate. To further improve the safety performance of the battery, in some embodiments, the secondary particles are formed by the aggregation of primary particles, the average thickness of the primary particles is 80 to 250 nm, and the specific surface area of ​​the secondary particles is 0.5 m². 2 It is 1.5m or more and is 1.5g or more. 2 The value is less than / g. By limiting the average thickness of the primary particles and the specific surface area of ​​the secondary particles, it is possible to ensure that the contact area between the positive electrode material and the electrolyte is limited, while also allowing the power performance to be fully realized.

[0052] Conventional technologies tend to increase the capacity and initial Coulomb efficiency of lithium-rich cathode materials by means of acid corrosion on the surface. For example, one method is to form a spinel-type structure on the surface of the cathode material to increase the conductivity of surface lithium ions. However, cathode materials that have undergone such treatment have many fresh interfaces formed and the interparticle gaps increase significantly, so the specific surface area is usually 2.0 m². 2 / g or more, and consequently 3.0m 2 The concentration is greater than / g, and the increase in specific surface area and fresh interface inevitably leads to an intensification of side reactions at the interface. The specific surface area of ​​the secondary particles according to this application is 0.5 m². 2 It is 1.5m or more and is 1.5g or more. 2 By ensuring that the value is less than / g and that the positive electrode material has specific pores, and by ensuring the power performance and capacitance of the positive electrode material, it is possible to fully utilize the performance of the positive electrode material.

[0053] In conventional technologies, compared to ternary cathode materials, lithium-rich cathode materials exhibit higher lattice stress during the electrochemical reaction process, resulting in a tendency for slightly lower dynamic performance. In the cathode material of this application, the average thickness of primary particles is 80-250 nm, which ensures low internal stress in individual particles, allowing lithium ions to be smoothly intercalated and released, and enabling the cathode material to fully demonstrate its performance. If the average thickness of primary particles is greater than 250 nm, it leads to dynamic problems due to excessive thickness, affecting power performance and capacity. If the average thickness of primary particles is less than 80 nm, it is too thin, causing a rapid decrease in compressive density and particle strength, while the specific surface area increases significantly.

[0054] This application does not limit the specific values ​​of the lithium-rich amount γ and average porosity β% of the cathode material, as long as the above relationship is satisfied. For example, in some embodiments, β is 7 to 13 and / or the lithium-rich amount γ is 0.09 to 0.21.

[0055] This application does not limit the specific material and size of the coating layer. For example, in some embodiments, the thickness of the coating layer is 2 to 10 nm, and / or the ratio of the total molar amount of the coating layer material to the total molar amount of the cathode material is (0.2 to 1.0):100, and / or the coating layer material is a phosphate and / or an inert oxide, wherein the phosphate includes at least one of AlPO4 and LiNiPO4, and the inert oxide includes at least one of Al2O3, TiO2, ZrO2, and La2O3. By coating with the above inert oxide and / or phosphate coating layer, the cathode material can be adapted to a high voltage window, and compared to ternary cathode materials, the cathode material of this application can maintain high stability in a higher voltage window to meet the requirements of industrialization.

[0056] In a second aspect, the present application provides a method for manufacturing a positive electrode material according to the first aspect, the manufacturing method being: The process involves mixing a metal salt solution, an alkaline solution, and an oxidizing agent to obtain a reaction system, and then allowing a precipitate to form in the reaction system to obtain a precursor, wherein the oxidizing agent contains sodium hypochlorite, and the concentration of sodium hypochlorite in the reaction system is 0.2 to 2 g / L. The method includes the steps of: mixing a precursor, a lithium salt, and a pore-forming agent to obtain a first mixture; and performing a first sintering treatment on the first mixture to obtain a cathode material.

[0057] The metal salt solution may also be a metal sulfate solution, with a concentration of 2-3 mol / L, and the alkaline solution may be sodium hydroxide, with a concentration of 5-10 mol / L.

[0058] In conventional techniques, the oxygen content is required to be extremely low during the synthesis process of ternary cathode material precursors. Otherwise, the shape of the precursor becomes irregular, aggregation occurs, the crystal structure changes, and a different phase may be generated. The inventors' research has confirmed that the concentration of the oxidizing agent directly affects the density of the precursor, which in turn affects the porosity of the cathode material. This is because the concentration of the oxidizing agent affects the kinetic characteristics of the precipitation reaction. This invention adjusts the concentration of the oxidizing agent to oxygenate some elements in the reaction system, nucleate and grow some elements individually, and allow transition metals to bond and grow on the surface of existing primary particles. This suppresses the primary particle thickness from becoming too thick, adjusts the density of the precursor, and controls the particle size and porosity of the subsequently formed secondary particles, which is advantageous for adjusting the Dv50 value and average porosity of the final cathode material.

[0059] Furthermore, the concentration of sodium hypochlorite shows a negative correlation with the particle size of the target secondary particles; that is, the higher the concentration of sodium hypochlorite, the smaller the particle size of the target secondary particles, and the lower the concentration of sodium hypochlorite, the larger the particle size of the target secondary particles. The concentration of sodium hypochlorite and the proportion of manganese atoms in the precursor show a positive correlation. This is because the higher the proportion of manganese, the higher the proportion of manganese-rich phase in the cathode material, requiring an improvement in porosity, which in turn requires a corresponding increase in the amount of sodium hypochlorite used. Therefore, the concentration of sodium hypochlorite and the proportion of manganese atoms show a positive correlation. In other words, as the proportion of manganese atoms in nickel-cobalt-manganese increases, the amount of sodium hypochlorite used needs to be increased accordingly.

[0060] This invention further adjusts the average porosity of a target cathode material using a porosity-forming agent. After thoroughly mixing the precursor, lithium salt, doped element-containing compound, and porosity-forming agent, a first sintering treatment is performed. During the first sintering treatment, the porosity-forming agent begins to decompose when the temperature drops below 400°C, generating gas. This occurs prior to, or simultaneously with, the lithification of the oxide produced by the decomposition of the hydroxide precursor into an ordered, layered lithium-rich cathode material. Therefore, during the process of lithification of the transition metal oxide into a lithium-rich cathode material, the porosity-forming agent continuously releases a certain amount of gas, achieving the objective of producing a cathode material with a specific average porosity. The above method according to this invention enables high-level control of the average porosity of the cathode material, thereby maximizing its power performance. At the same time, sufficient "breathing" space in the unit cell improves the stability of the crystal structure, ensures the structural strength of secondary particles, reduces the volume change rate and porosity change rate of secondary particles, extends the long cycle life of the cathode material in batteries, and provides assurance for stable use in large-scale cells.

[0061] In some embodiments, the first mixture further contains a doped element-containing compound to form a coating layer during the second sintering process, and the doped element-containing compound includes a doped metal element-containing compound and a doped non-metal element-containing compound. and / or, after the first sintering process, the invention further includes the steps of mixing the product of the first sintering process with the coating layer material to obtain a second mixture, and performing a second sintering process on the second mixture to obtain a positive electrode material. The second sintering process forms a coating layer on the surface of the secondary particles, reduces side reactions between the positive electrode material and the electrolyte, and improves the stability of the battery system.

[0062] This application does not overly limit the parameters of the above manufacturing process, but for example, in some examples, the conditions for the precipitation reaction are a stirring speed of 700-800 rpm, a temperature of 50-70°C, and a pH of 9.5-11.5, while the temperature for the first sintering treatment is 800-950°C and the holding time is 10-15 hours.

[0063] When the coating material contains only inert oxides, the temperature of the second sintering treatment is 500-800°C, the heating rate is 5-10°C / min, and the time is 5-10h. When the coating material contains only phosphates, the temperature of the second sintering treatment is 700-900°C, the heating rate is 5-10°C / min, and the time is 5-10h. The first sintering treatment is performed in an air atmosphere. When the coating material contains both inert oxides and phosphates, the temperature of the second sintering treatment is 700-800°C, the heating rate is 5-10°C / min, and the time is 5-10h.

[0064] This application does not limit the specific type or amount of porosity-forming agent, but the porosity-forming agent may be an ammonium salt whose coordinating polyanion can be gasified by heat. For example, in some examples, the mass of the porosity-forming agent is 0.1 to 1.0 wt% of the mass of the precursor, and the porosity-forming agent includes at least one of ammonium carbonate, ammonium sulfate, ammonium persulfate, ammonium nitrate, and ammonium chloride.

[0065] In addition, the above manufacturing process usually requires the addition of an excess of lithium; that is, in addition to satisfying the molar ratio of lithium in the chemical formula, an additional 3-5 at% of lithium needs to be added to prevent lithium loss during the manufacturing process. In the specific implementation process of this application, the actual molar amount of lithium salt / theoretical molar amount of lithium = 1.03-1.05, and the theoretical molar amount of lithium satisfies the amount of lithium salt added in the chemical formula.

[0066] In a third aspect, the present invention provides a positive electrode plate comprising a positive electrode material manufactured by a manufacturing method according to the first aspect or the second aspect.

[0067] In some embodiments, the positive electrode plate includes a current collector and a positive electrode active material layer on at least one functional surface of the current collector, the positive electrode active material layer including a positive electrode material, a conductive agent, and a binder. The mass of the positive electrode material accounts for 94 wt% or more of the total mass of the positive electrode active material layer.

[0068] The positive electrode plate of the present invention may be manufactured by conventional means in the art. Specifically, the positive electrode material, conductive agent, and binder are uniformly dispersed in a solvent to obtain a positive electrode active layer slurry. Then, the positive electrode active layer slurry is applied to at least one functional surface of a positive electrode current collector, dried, and the positive electrode plate of the present invention can be obtained.

[0069] In this application, there are no particular limitations on the specific types of conductive agents and binders. Conventional materials in the art can be selected as components of conductive agents, binders, etc. For example, the conductive agent can be selected from one or more of conductive carbon black, carbon nanotubes, conductive graphite, and graphene, and the binder can be selected from one or more of polyvinylidene fluoride (PVDF), acrylic acid-modified PVDF, polyacrylate polymers, polyimide, styrene-butadiene rubber, and styrene-acrylic rubber.

[0070] This application does not specifically limit the coating method, and the cathode active layer slurry can be coated using any coating method such as gravure coating, extrusion coating, spray coating, or screen printing.

[0071] In a fourth aspect, the present invention provides a lithium-ion battery, the lithium-ion battery including a positive electrode plate according to the third aspect.

[0072] In some embodiments, the lithium-ion battery of this application further comprises a separator, a negative electrode plate, and an electrolyte, in addition to the positive electrode plate. The composition of the negative electrode plate may refer to conventional negative electrode plates in the art, and the separator may be a separator conventionally used in the art, such as a PP film or a PE film. The negative electrode plate is selected from at least one of lithium foil, graphite, or silicon carbon negative electrode.

[0073] The lithium-ion battery of this application can be manufactured by conventional methods in this field. Specifically, a positive electrode plate, a separator, and a negative electrode plate are sequentially stacked and installed, a cell is obtained by lamination or winding, and then the lithium-ion battery can be obtained by processes such as firing, liquid injection, molding, and packaging.

[0074] With the negative electrode plate exemplified as metallic lithium foil, in several embodiments, the lithium-ion battery, after 200 cycles at 2.5-4.55V under charge / discharge conditions of 0.5C / 1.0C, showed an increase in the average cross-sectional porosity of the positive electrode material on the positive electrode plate of less than 2%.

[0075] In a fifth aspect, the present application provides a power consumption device including a lithium-ion battery according to a fourth aspect, preferably the power consumption device including an electric vehicle, a manned electric aircraft, and an unmanned aircraft.

[0076] The present application will be further explained below through specific examples and comparative examples.

[0077] Example 1

[0078] (1) A metal salt solution was injected into a reaction vessel at a rate of 10 mL / min, a sodium hydroxide solution at a rate of 8.0 ± 0.2 mL / min, and sodium hypochlorite at a rate of 0.009 g / min. The stirring speed was 800 rpm, the temperature was 50°C, and the pH was 10.6. The reaction was allowed to proceed for a certain period of time to obtain a precursor with a suitable particle size of 6-8 μm. The metal salt solution was a sulfate solution containing nickel and manganese (with a molar ratio of nickel to manganese of 35:65), the metal salt concentration was 2 mol / L, the sodium hydroxide concentration in the sodium hydroxide solution was 5 mol / L, and the concentration of sodium hypochlorite in the reaction system was adjusted to 0.5 g / L. (2) Precursor Ni 0.35 Mn 0.65 (OH)2 and lithium salt Li2CO3 were added in amounts of 1.0 mol and 0.67 mol respectively (3 at% excess relative to 0.65 mol), and ammonium sulfate (the mass of ammonium sulfate was 0.6% of the mass of the precursor) was added and thoroughly mixed to obtain the first mixture. The first mixture was subjected to the first sintering treatment in an air atmosphere at a temperature of 900°C for a holding time of 12 hours, and then allowed to cool naturally to room temperature, and the positive electrode material Li 1.13 Ni 0.305 Mn 0.565 O2 was obtained.

[0079] Example 2

[0080] The manufacturing process is almost identical to that of Example 1, but with the following differences: Except for replacing "the concentration of sodium hypochlorite in the reaction system was set to 0.5 g / L" in step (1) with "the concentration of sodium hypochlorite in the reaction system was set to 0.8 g / L", all other conditions remain unchanged to obtain the precursor. Except for replacing the precursor of Example 1 with the precursor of this example in step (2), replacing "ammonium sulfate" with "ammonium carbonate", and replacing "the mass of ammonium sulfate is 0.6% of the mass of the precursor" with "the mass of ammonium carbonate is 0.2% of the mass of the precursor", all other conditions remain unchanged to obtain the cathode material Li 1.131 Ni 0.302 Mn 0.567 O2 was obtained.

[0081] Example 3

[0082] The manufacturing process is almost identical to that of Example 1, but with the following differences: Except for replacing "the concentration of sodium hypochlorite in the reaction system was set to 0.5 g / L" in step (1) with "the concentration of sodium hypochlorite in the reaction system was set to 1.5 g / L", all other conditions remain unchanged to obtain the precursor. Except for replacing the precursor of Example 1 with the precursor of this example in step (2), replacing "ammonium sulfate" with "ammonium nitrate", and replacing "the mass of ammonium sulfate is 0.6% of the mass of the precursor" with "the mass of ammonium nitrate is 0.5% of the mass of the precursor", all other conditions remain unchanged to obtain the cathode material Li 1.13 Ni 0.308 Mn 0.562 O2 was obtained.

[0083] Example 4

[0084] The manufacturing process is almost identical to that of Example 1, but with the following differences: In step (1), replace "the metal salt solution is a sulfate solution containing nickel and manganese (with a molar ratio of nickel to manganese of 35:65)" with "the metal salt solution is a sulfate solution containing nickel and manganese (with a molar ratio of nickel to manganese of 25:75)", and replace "the concentration of sodium hypochlorite in the reaction system was set to 0.5 g / L" with "the concentration of sodium hypochlorite in the reaction system was set to 1.5 g / L". Other conditions remain unchanged to obtain the precursor. In step (2), replace the precursor of Example 1 with the precursor of this example, replace "ammonium sulfate" with "ammonium carbonate", and replace "the mass of ammonium sulfate is 0.6% of the mass of the precursor" with "the mass of ammonium carbonate is 0.8% of the mass of the precursor". Other conditions remain unchanged to obtain the cathode material Li 1.203 Ni 0.2 Mn 0.597 O2 was obtained.

[0085] Example 5

[0086] It is almost the same as the manufacturing process of Example 1, but there are the following differences. Except for replacing "The metal salt solution is a sulfate solution containing nickel and manganese (the molar ratio of nickel to manganese is 35:65)" in step (1) with "The metal salt solution is a sulfate solution containing nickel, manganese (the molar ratio of nickel to manganese is 40:60)", and replacing "The concentration of sodium hypochlorite in the reaction system was made 0.5 g / L" with "The concentration of sodium hypochlorite in the reaction system was made 1.3 g / L", other conditions are not changed to obtain a precursor. In step (2), except for replacing the precursor of Example 1 with the precursor of this example, replacing "ammonium sulfate" with "ammonium chloride", and replacing "The mass of ammonium sulfate is 0.6% of the mass of the precursor" with "The mass of ammonium chloride is 0.8% of the mass of the precursor", other conditions are not changed, and the cathode material Li 1.091 Ni 0.365 Mn 0.544 O2 was obtained.

[0087] Example 6

[0088] It is almost the same as the manufacturing process of Example 1, but there are the following differences. Except for replacing "The metal salt solution is a sulfate solution containing nickel and manganese (the molar ratio of nickel to manganese is 35:65)" in step (1) with "The metal salt solution is a sulfate solution containing nickel, cobalt, and manganese (the molar ratio of nickel, cobalt, and manganese is 30:10:60)", and replacing "The concentration of sodium hypochlorite in the reaction system was made 0.5 g / L" with "The concentration of sodium hypochlorite in the reaction system was made 1.2 g / L", other conditions are not changed to obtain a precursor. In step (2), except for replacing the precursor of Example 1 with the precursor of this example, replacing "ammonium sulfate" with "ammonium persulfate", and replacing "The mass of ammonium sulfate is 0.6% of the mass of the precursor" with "The mass of ammonium persulfate is 0.3% of the mass of the precursor", other conditions are not changed, and the cathode material Li 1.313 Ni 0.262 Co 0.087 Mn 0.52 O2 was obtained.

[0089] Example 7

[0090] It is almost the same as the manufacturing process of Example 1, but there are the following differences. Except for replacing "the concentration of sodium hypochlorite in the reaction system was set to 0.5 g / L" in step (1) with "the concentration of sodium hypochlorite in the reaction system was set to 1.0 g / L", other conditions remain unchanged to obtain a precursor. In step (2), replace the precursor of Example 1 with the precursor of this example, replace "ammonium sulfate" with "ammonium chloride", replace "the mass of ammonium sulfate is 0.6% of the mass of the precursor" with "the mass of ammonium chloride is 0.5% of the mass of the precursor", increase the doping element-containing compounds WO3, Nb2O5, Al2O3, and NH4H2PO4 in the first mixture, and the ratios of the atomic weights of W, Nb, Al, and P elements to the atomic weight of the nickel element in the precursor are 1:29.2, 1:29.2, 1:29.2, and 1:29.2 respectively. Except for this, other conditions remain unchanged, and the cathode material Li 1.13 Ni 0.292 Mn 0.548 W 0.01 Nb 0.01 Al 0.01 P 0.01 O2 was obtained.

[0091] Example 8

[0092] The manufacturing process is almost identical to that of Example 1, but with the following differences: Except for replacing "the concentration of sodium hypochlorite in the reaction system was set to 0.5 g / L" in step (1) with "the concentration of sodium hypochlorite in the reaction system was set to 0.9 g / L", all other conditions remain unchanged to obtain the precursor. In step (2), the precursor of Example 1 is replaced with the precursor of this example, "ammonium sulfate" is replaced with "ammonium nitrate", and "the mass of ammonium sulfate is 0.6% of the mass of the precursor" is replaced with "the mass of ammonium nitrate is 0.5% of the mass of the precursor". The doped element-containing compounds WO3, Nb2O5, Al2O3, and NH4H2PO4 are increased in the first mixture, and the ratios of the atomic weights of W, Nb, Al, and P elements to the atomic weight of nickel element in the precursor are 1:29.2, 1:29.2, 1:29.2, and 1:29.2, respectively, all other conditions remain unchanged to obtain the first sintered product Li 1.13 Ni 0.292 Mn 0.548 W 0.01 Nb 0.01 Al 0.01 P 0.01 O2 is obtained, Step (3) is increased, and in step (3), the product of the first sintering treatment is 0.03 mol% Al2O3 and 0.02 mol% TiO 2と Mixing with the other to obtain a second mixture, and performing a second sintering treatment on the second mixture, sintering at 550°C for 10 hours in an air atmosphere, to obtain a lithium-rich cathode material 0.03Al2O3·0.02TiO2·Li ​​with a composite coating of Al2O3 and TiO2. 1.13 Ni 0.292 Mn 0.548 W 0.01 Nb 0.01 Al 0.01 P 0.01 O2 was obtained.

[0093] Example 9

[0094] The manufacturing process is almost identical to that of Example 1, but with the following differences: Except for changing "the concentration of sodium hypochlorite in the reaction system was set to 0.5 g / L" in step (1) to "the concentration of sodium hypochlorite in the reaction system was set to 0.9 g / L", all other conditions remain unchanged to obtain the precursor, and in step (2), the precursor of Example 1 is replaced with the precursor of this example, "ammonium sulfate" is replaced with "ammonium carbonate", and "the mass of ammonium sulfate is 0.6% of the mass of the precursor" is replaced with "the mass of ammonium carbonate is 0.6% of the mass of the precursor", and Li2C The amount of O3 used was reduced from 0.67 mol (3 at% excess compared to 0.65 mol) to 0.492 mol (3 at% excess compared to 0.477 mol), and the amount of doped element-containing compounds WO3, Nb2O5, Al2O3, NH4H2PO4, LiF, and Li2S was increased in the first mixture. The ratios of the atomic weights of W, Nb, Al, P, F, and S elements to the atomic weight of nickel element in the precursor were 1:29.4, 1:29.4, 1:29.4, 1:29.4, and 1:2.94, respectively. Other conditions remained unchanged, except for the cathode material Li 1.129 Ni 0.294 Mn 0.547 W 0.01 Nb 0.01 Al 0.01 P 0.01 O 1.8 F 0.1 S 0.1 I obtained it.

[0095] Example 10

[0096] The manufacturing process is almost identical to that of Example 1, but with the following differences: Except for changing "the concentration of sodium hypochlorite in the reaction system to 0.5 g / L" in step (1) to "the concentration of sodium hypochlorite in the reaction system to 0.9 g / L", all other conditions remain unchanged to obtain the precursor. In step (2), the precursor of Example 1 is replaced with the precursor of this example, "ammonium sulfate" is replaced with "ammonium carbonate", and "the mass of ammonium sulfate is 0.6% of the mass of the precursor" is replaced with "the mass of ammonium carbonate is 0.7% of the mass of the precursor", and Li2CO3 The amount used was reduced from 0.67 mol (3 at% excess compared to 0.65 mol) to 0.492 mol (3 at% excess compared to 0.477 mol), and the amount of doped element-containing compounds WO3, Nb2O5, Al2O3, NH4H2PO4, LiF, and Li2S was increased in the first mixture. The ratios of the atomic weights of elements W, Nb, Al, P, F, and S to the atomic weight of nickel in the precursor were 1:29.4, 1:29.4, 1:29.4, 1:29.4, 1:2.94, and 1:2.94, respectively. Other conditions remained unchanged, and the first sintered product Li 1.129 Ni 0.294 Mn 0.547 W 0.01 Nb 0.01 Al 0.01 P 0.01 O 1.8 F 0.1 S 0.1 Obtained, Step (3) is increased, in which the product of the first sintering treatment is mixed with 0.03 mol% Al2O3 and 0.03 mol% AlPO4 to obtain a second mixture, the second mixture is subjected to a second sintering treatment, the sintering temperature is 550°C, the sintering time is 10h, and the positive electrode material is (0.03Al2O3·0.03AlPO4·Li 1.13 Ni 0.292 Mn 0.548 W 0.01 Nb 0.01 Al 0.01 P 0.01 O2 was obtained.

[0097] Comparative Example 1

[0098] The manufacturing process is almost identical to that of Example 1, but with the following differences: Except for changing "the concentration of sodium hypochlorite in the reaction system to 0.5 g / L" in step (1) to "the concentration of sodium hypochlorite in the reaction system to 2.5 g / L", all other conditions remain unchanged to obtain the precursor. Except for changing "the precursor of Example 1 to the precursor of this comparative example" in step (2) and changing "the mass of ammonium sulfate is 0.6% of the mass of the precursor" to "the mass of ammonium bicarbonate is 3.0% of the mass of the precursor", all other conditions remain unchanged to obtain the cathode material Li 1.13 Ni 0.304 Mn 0.566 O2 was obtained.

[0099] Comparative Example 2

[0100] The manufacturing process is almost identical to that of Example 1, but with the following differences: Except for replacing "the concentration of sodium hypochlorite in the reaction system was set to 0.5 g / L" in step (1) with "the concentration of sodium hypochlorite in the reaction system was set to 2.2 g / L", all other conditions remain unchanged to obtain the precursor, and in step (2), replace the precursor of Example 1 with the precursor of this comparative example, and replace "the mass of ammonium sulfate is 0.6% of the mass of the precursor" with "the mass of ammonium bisulfate is 1.6% of the mass of the precursor", all other conditions remain unchanged to obtain the cathode material Li 1.131 Ni 0.304 Mn 0.565 O2 was obtained.

[0101] Comparative Example 3

[0102] The manufacturing process is almost identical to that of Example 1, but with the following differences: Except for not adding sodium hypochlorite to the reaction system in step (1), all other conditions remain unchanged to obtain the precursor, and in step (2), the precursor of Example 1 is replaced with the precursor of this comparative example, and except for not adding ammonium sulfate, all other conditions remain unchanged to obtain the cathode material Li 1.129 Ni 0.307 Mn 0.563 O2 was obtained.

[0103] Comparative Example 4

[0104] The manufacturing process is almost identical to that of Example 1, but with the following differences: In step (1), the phrase "the metal salt solution is a sulfate solution containing nickel and manganese (with a molar ratio of nickel to manganese of 35:65)" is replaced with "the metal salt solution is a sulfate solution containing nickel, cobalt, and manganese (with a molar ratio of nickel, cobalt, and manganese of 30:10:60)", and the phrase "the concentration of sodium hypochlorite in the reaction system is 0.5 g / L" is replaced with "the concentration of sodium hypochlorite in the reaction system is 2.4 g / L". Other conditions remain unchanged to obtain the precursor. In step (2), the precursor of Example 1 is replaced with the precursor of this comparative example, "ammonium sulfate" is replaced with "ammonium carbonate", and the phrase "the mass of ammonium sulfate is 0.6% of the mass of the precursor" is replaced with "the mass of ammonium carbonate is 2.3% of the mass of the precursor". Other conditions remain unchanged to obtain the cathode material Li 1.130 Ni 0.26 Co 0.089 Mn 0.521 O2 was obtained.

[0105] Comparative Example 5

[0106] The manufacturing process is almost identical to that of Example 1, but with the following differences: In step (1), the phrase "the metal salt solution is a sulfate solution containing nickel and manganese (with a molar ratio of nickel to manganese of 35:65)" is replaced with "the metal salt solution is a sulfate solution containing nickel, cobalt, and manganese (with a molar ratio of nickel, cobalt, and manganese of 30:10:60)", and no sodium hypochlorite is added to the reaction system. Other conditions remain unchanged to obtain the precursor. In step (2), the precursor of Example 1 is replaced with the precursor of this comparative example, and no ammonium sulfate is added. Other conditions remain unchanged to obtain the positive electrode material Li 1.129 Ni 0.261 Co 0.088 Mn 0.523 O2 was obtained.

[0107] Test example

[0108] 1. Measurement of porosity The cathode material is polished using a cross-sectional polishing device, photographed with a scanning electron microscope, and then the grayscale of the cathode material cross-section is quantitatively analyzed using ImageJ software. Specifically, the RGB threshold is first set to 90, and the percentage of the area in the RGB range 0 to 90 in the cathode material photograph is calculated and designated as X1. Similarly, the percentage of the area in the RGB range 0 to 252 in the cathode material photograph is recorded and designated as X2. Then, the cross-sectional porosity of the cathode material is calculated as X1 / X2 × 100%. The average porosity of the cathode material is obtained by measuring the porosity of 20 or more secondary particles from the sample and calculating the average value.

[0109] 2. Particle size measurement D min In a volume-based particle size distribution, the particle size at which the volume accumulation reaches 0% from the smallest particle size side of the cathode material is D. min This indicates that D 50 In a volume-based particle size distribution, the particle size when the volume accumulation reaches 50% from the smallest particle size side of the positive electrode material particles is D 50 This indicates that...

[0110] 3. Energy density The energy density recorded in Table 1 is the volumetric energy density of the positive electrode material itself coated on the positive electrode plate, i.e., average discharge voltage × specific capacitance × plate compression density.

[0111] 4. Electrochemical performance test The above positive electrode material, conductive agent Super-P, and binder PVDF were mixed in a mass ratio of 92:4:4, and an appropriate amount of NMP solution was added to form a slurry. The slurry was applied to aluminum foil, dried, and then baked in a vacuum oven at 150°C for 12 hours. After that, the secondary battery was assembled in a glove box under an Ar gas atmosphere. A coin-type CR2032 battery was assembled using metallic lithium as the negative electrode and a solution of 1 mol / L LiPF6 dissolved in a mixed organic solvent with a volume ratio of EC:EMC = 3:7 as the electrolyte. (1) 0.1C specific capacity, discharge voltage: 0.1C = 23mAg-1 The battery is discharged at a current density of 4.55V, and discharged from a full charge to a voltage of 2.5V. The corresponding capacity obtained is the specific discharge capacity at 0.1C, and the average discharge voltage for 0.1C discharge is obtained by calculating the specific energy / specific capacity of 0.1C discharge. (2)2.0C specific capacity: 2.0C=460mAg -1 The battery was discharged at a current density of 4.55V, and discharged from a full charge to a voltage of 2.5V. The resulting capacity is a discharge ratio capacity of 2.0C. (3) 2C / 0.1C capacity retention rate: The value obtained by dividing the 2.0C discharge ratio capacity of (2) by the 0.1C discharge ratio capacity of (1) is the 2C / 0.1C capacity retention rate. (4) Energy retention rate after 200 cycles: After 200 cycles using a 0.5C / 1.0C charge / discharge method, the ratio of the discharge energy at the 200th cycle to the discharge energy at the first cycle is the energy retention rate after 200 cycles. (5) Cycle later If the average porosity of the cross-sectional area is increased by 0.5C / 1.0C in 200 cycles, and the average porosity of the cross-sectional area of ​​the material before the cycle is P and the average porosity of the cross-sectional area of ​​the material after the cycle is Q, then (QP) / P × 100% is the number of cycles. later This is the rate of increase in the average cross-sectional porosity.

[0112] Refer to Figures 1 to 21 for the SEM test, and the test results are shown in Table 1.

[0113] [Table 1]

[0114] As can be seen from Table 1, all of the examples satisfy δ = β - [2α + 75γ] / 3 and 0 ≤ δ ≤ 4.0. The 2C / 0.1C capacity retention rate of the examples is 84% ​​or higher, and the energy retention rate after 200 cycles is 94% or higher, both of which are higher than those of the comparative example. The increase in average porosity of the positive electrode material in the examples after 200 cycles is less than 2%, which is much lower than that of the comparative example. Furthermore, the compressive density, specific capacity, discharge voltage, and energy density of the positive electrode plate in the examples are equivalent to those of the comparative example. ,child As can be seen from the above, the cathode material according to the present invention can maximize the specific capacity, rate performance, cycle performance, and long-period life of lithium-ion batteries manufactured with the cathode material by matching the average particle size, lithium-rich content, and average porosity with each other, and can particularly enhance the electrochemical performance under high voltage conditions.

[0115] The preferred specific embodiments and experimental verifications of the present application have been described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present application without requiring any creative effort. For this reason, all technical solutions that a person skilled in the art can obtain by logical analysis, reasoning, or limited experimentation based on the prior art in accordance with the concept of the present application should fall within the scope of protection determined by the claims.

[0116] <Cross-reference of related applications> This application claims priority to the Chinese patent application filed with the China National Patent Office on September 13, 2023, with application number 202311186638.4 and title "Cathode Material, Method for Manufacturing the Same, and Applications," all of which are incorporated herein by reference.

Claims

1. A positive electrode material, wherein the value of Dv50 of the positive electrode material is α, and the unit is μm. The lithium-rich amount of the positive electrode material is γ. The average porosity of the cathode material is β% as a percentage. α, β, and γ are positive electrode materials that satisfy δ = β - [2α + 75γ] / 3 and 0 ≤ δ ≤ 4.

0.

2. The positive electrode material according to claim 1, wherein the positive electrode material includes secondary particles and a coating layer that covers the surface of at least a portion of the secondary particles.

3. The positive electrode material according to claim 2, wherein the total molar amount of elements distributed in cationic form in the secondary particles is A, and the total molar amount of elements distributed in anionic form in the secondary particles is B, and A and B satisfy 0.985 ≤ A / B ≤ 1.

0.

4. The secondary particles include doped metal elements distributed in cationic form and doped nonmetal elements distributed in anionic form. However, the molar ratio of the doped metal element to other elements distributed in the secondary particles in the form of cations other than lithium ions is 5% or less, and / or The positive electrode material according to claim 3, wherein the molar ratio of the doped nonmetallic element to the total amount of elements distributed in anionic form in the secondary particles is 10% or less.

5. The chemical formula of the secondary particle is Li １＋ｘ－２ｙ M ｚ M' １－ｘ－ｚ O ２－ｙ－ｔ R ｔ And M is Ni ａ Co ｂ Mn ｃ Let a + b + c = 1.0, 0 ≤ b ≤ 0.10, a ≥ 2b, 1.5 ≤ c / (a + b) ≤ 3.0, x = (c - a) / (2 + c - a), 0.985 ≤ (2 - 2y) / (2 - y) ≤ 1.0, (19 - 19x) / 20 ≤ z ≤ (1 - x), 0 ≤ t ≤ (2 - y) / 10. The positive electrode material according to any one of claims 2 to 4, wherein M' is a doped metallic element and R is a doped nonmetallic element.

6. The aforementioned M' includes at least one of Cr, Mo, W, Ta, Nb, P, Sb, Te, Hf, Ce, Ti, Zr, Sn, La, Al, Mg, Fe, K, Na, and / or The positive electrode material according to claim 5, wherein R includes at least one of F and S.

7. The Dv50 of the positive electrode material is 2.5 to 10.6 μm, and / or The minimum particle size Dv of the positive electrode material ｍｉｎ is 0.6 μm or more, and / or The secondary particles are formed by the aggregation of primary particles, and the average thickness of the primary particles is 80 to 250 nm, and / or The specific surface area of ​​the aforementioned secondary particle is 0.5 m². ２ It is 1.5 m or more and ２ / g or less, and / or β is 7 to 13, and / or The positive electrode material according to any one of claims 2 to 6, wherein the lithium-rich amount γ is 0.09 to 0.

21.

8. The ratio of the molar amount of the coating layer material to the total molar amount of the positive electrode material is (0.2 to 1.0):100, and / or, The coating layer material is a phosphate and / or an inert oxide, and the phosphate is AlPO ４ LaPO ４ It includes at least one of the following, and the inert oxide is Al ２ O ３ , TiO ２ , ZrO ２ La ２ O ３ A positive electrode material according to any one of claims 2 to 7, comprising at least one of the following.

9. A method for manufacturing a positive electrode material according to any one of claims 1 to 8, The process involves a step of mixing a metal salt solution, an alkaline solution, and an oxidizing agent to obtain a reaction system, and then allowing a precipitation reaction to occur in the reaction system to obtain a precursor, wherein the oxidizing agent contains sodium hypochlorite, and the concentration of the oxidizing agent in the reaction system is 0.2 to 2 g / L. A manufacturing method comprising the steps of: mixing a precursor, a lithium salt, and a pore-forming agent to obtain a first mixed material; and performing a first sintering treatment on the first mixed material to obtain a positive electrode material.

10. The first mixture further contains a doped element-containing compound, and / or The manufacturing method according to claim 9, further comprising the steps of: mixing the product of the first sintering process with a coating layer material after the first sintering process to obtain a second mixture; and performing a second sintering process on the second mixture to obtain a positive electrode material.

11. The conditions for the aforementioned precipitation reaction are a stirring speed of 700-800 rpm, a temperature of 50-70°C, and a pH of 9.5-11.

5. The temperature of the first sintering process is 800 to 950°C, the holding time is 10 to 15 hours, and / or The coating layer material contains an inert oxide, the temperature of the second sintering treatment is 500 to 800°C, the heating rate is 5 to 10°C / min, the time is 5 to 10 hours, and / or The manufacturing method according to claim 10, wherein the coating layer material contains a phosphate, the temperature of the second sintering treatment is 700 to 900°C, the heating rate is 5 to 10°C / min, and the time is 5 to 10 hours.

12. The mass of the pore-forming agent is 0.1 to 1.0 wt% of the mass of the precursor. The method for producing a pore-forming agent according to any one of claims 9 to 10, wherein the pore-forming agent comprises at least one of ammonium carbonate, ammonium sulfate, ammonium persulfate, ammonium nitrate, and ammonium chloride.

13. A positive electrode plate comprising a positive electrode material according to any one of claims 1 to 8 or a positive electrode material manufactured by a manufacturing method according to any one of claims 9 to 12.

14. The positive electrode plate includes a current collector and a positive electrode active material layer on at least one functional surface of the current collector. The positive electrode plate according to claim 13, wherein the positive electrode active material layer comprises the positive electrode material, conductive agent, and binder described in any one of claims 1 to 8, and the mass of the positive electrode material accounts for 94 wt% or more of the total mass of the positive electrode active material layer.

15. A lithium-ion battery comprising the positive electrode plate described in claim 13.

16. The lithium-ion battery further comprises a separator, a negative electrode plate, and an electrolyte. The lithium-ion battery according to claim 15, wherein the negative electrode plate is selected from at least one of lithium foil, graphite, and silicon carbon negative electrode.

17. The lithium-ion battery according to claim 15 or 16, wherein after 200 cycles under charge-discharge conditions of 2.5 to 4.55 V and 0.5 C / 1.0 C, the increase rate of the average cross-sectional porosity of the positive electrode material on the positive electrode plate is less than 2%.

18. A power consumption device comprising a lithium-ion battery according to any one of claims 15 to 17, wherein the power consumption device includes an electric vehicle, a manned electric aircraft, and an unmanned aircraft.

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