Positive electrode active material, positive electrode sheet, secondary battery and power-consuming device

Abstract

Positive electrode active material, characterized in that the chemical formula of the positive electrode active material is Li a Ni x Co y M 1-x-y O2 is defined as follows, where M comprises one or more of Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg and Nb, where 0.55 ≤ x ≤ 1.0, 0 ≤ y ≤ 0.45, 0.8 ≤ a ≤ 1.2, and where the positive electrode active material has a hollow structure, wherein the inner diameter d1 of the hollow structure is 0.3 µm to 5 µm.

Description

Technical field

[0001] The present application relates to the technical field of secondary batteries, in particular a positive electrode active material and a method for its production, a positive electrode sheet, a secondary battery and a power-consuming device. State of the art

[0002] Secondary batteries are characterized by high capacity, long lifespan, and other advantages, and are therefore frequently used in electronic devices such as mobile phones, laptops, e-bikes, electric vehicles, electric aircraft, electric boats, electric toy cars, electric toy ships, electric toy airplanes, and power tools. As secondary battery technology has advanced significantly, higher demands are being placed on their performance. To improve performance, the materials used in secondary batteries, such as the positive electrode active material, are typically optimized and improved. Acting as a carrier for metal ions and electrons in the secondary battery, the positive electrode active material is responsible for storing and releasing energy and thus has a significant impact on the battery's performance.However, even with the currently improved positive electrode active material, the secondary battery still exhibits insufficient cycle and rate performance. Disclosure of the invention

[0003] In light of the above-mentioned topic, the present application aims to provide a positive electrode active material, wherein the positive electrode active material has a hollow structure with an inner diameter of 0.3 µm to 5 µm. This effectively increases the cycle life of the battery while simultaneously providing excellent rate performance.

[0004] A first aspect of the present application provides a positive electrode active material, wherein the chemical formula of the positive electrode active material is Li a Ni x Co y M 1-x-y O2 is called, where M comprises one or more of Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg and Nb, where 0.55 ≤ x ≤ 1.0, 0 ≤ y ≤ 0.45, 0.8 ≤ a ≤ 1.2, and where the positive electrode active material has a hollow structure, wherein the inner diameter d1 of the hollow structure is 0.3 µm to 5 µm.

[0005] On the one hand, the hollow structure buffers the volume changes of the positive electrode active material during charging and discharging, thus stabilizing the structure and improving cycle performance. On the other hand, the hollow positive electrode active material features more three-dimensional channels, increasing the contact area between the material and the electrolyte solution, shortening the migration distance of the lithium ions, and reducing the battery's internal resistance, resulting in excellent rate performance. Furthermore, the hollow positive electrode active material simultaneously provides more active sites for lithium ions, increasing the capacity per gram of material and improving both the discharge capacity and energy density.

[0006] In any embodiment, the chemical formula Li applies a Ni x Co y M 1-x-yO2: 0.9 ≤ x ≤ 1.0, 0 ≤ y ≤ 0.1, 0.8 ≤ a ≤ 1.2, optional 0.95 ≤ x ≤ 0.995, 0 ≤ y ≤ 0.05, 0.8 ≤ a ≤ 1.2.

[0007] In any embodiment, the inner diameter d1 of the hollow structure is 1.5 µm to 5 µm, which further reduces the migration distance of the lithium ions and improves the rate performance of the battery.

[0008] In any embodiment, the positive electrode active material satisfies the following relationship: 1 ≤ Dv50 / (d1 + d2) ≤ 4,

[0009] where d1 in µm denotes the inner diameter of the hollow structure, d2 in µm denotes the outer wall thickness of the hollow structure, and Dv50 in µm denotes the Dv50 value of the positive electrode active material.

[0010] By controlling the Dv50 value of the positive electrode active material, the inner diameter d1 and the outer wall thickness d2 of the hollow structure such that 1 ≤ Dv50 / (d1 + d2) ≤ 4, the energy density and rate performance of the battery can be improved.

[0011] In any embodiment, the outer wall thickness d2 of the hollow structure is 3 µm to 10 µm, optionally 3 µm to 7 µm.

[0012] By controlling the outer wall thickness d2 of the hollow structure in a suitable area, the structural stability of the material can be increased, and the battery thus exhibits a high discharge capacity and energy density as well as excellent rate and cycle performance, which comprehensively improves the electrochemical performance of the battery.

[0013] In any embodiment, the Dv50 value of the positive electrode active material is 5 µm to 15 µm, optionally 8 µm to 10 µm.

[0014] By controlling the Dv50 value of the positive electrode active material within a suitable range, the energy density and rate performance of the battery can be increased.

[0015] In any embodiment, the porosity of the positive electrode active material is 0 to 20%, optionally 2% to 15%.

[0016] By controlling the porosity of the positive electrode active material within a suitable range, the battery exhibits high discharge capacity and energy density, as well as excellent rate and cycle performance, thereby comprehensively improving the electrochemical performance of the battery.

[0017] In any embodiment, the specific surface area of ​​the positive electrode active material is 0.4 m². 2 / g up to 1.4 m 2 / G.

[0018] By controlling the specific surface area of ​​the positive electrode active material in a suitable area, the battery exhibits a high discharge capacity and energy density, as well as excellent rate and cycle performance, thereby comprehensively improving the electrochemical performance of the battery.

[0019] In any embodiment, the SPAN value of the positive electrode active material is 1 to 1.5, optionally 1.2 to 1.4.

[0020] By controlling the SPAN value of the positive electrode active material within a suitable range, the discharge capacity of the battery can be increased.

[0021] In any embodiment, the area of ​​the (010) crystal plane of the positive electrode active material is greater than or equal to 6 µm². 2 .

[0022] By controlling the area of ​​the (010) crystal plane of the positive electrode active material to be greater than or equal to 6 µm 2The battery exhibits a high discharge capacity and energy density, as well as excellent rate and cycle performance, thereby comprehensively improving the electrochemical performance of the battery.

[0023] In any embodiment, the primary particle size of the positive electrode active material is 0.1 µm to 0.8 µm, optionally 0.15 µm to 0.3 µm.

[0024] By controlling the primary particle size of the positive electrode active material within a suitable range, the discharge capacity and energy density of the battery can be increased, and the battery's rate performance can be improved.

[0025] A second aspect of the present application provides a method for producing a positive electrode active material, comprising step (1) and step (2): Step (1): Mixing a mixture source containing a nickel source and a cobalt source with a hard template agent, a complexing agent and a precipitating agent and carrying out a co-precipitation reaction to obtain a precursor, wherein the mixture source optionally contains an M source, Step (2): Calcining the precursor with a lithium source to preserve the positive electrode active material, where the chemical formula of the positive electrode active material Li a Ni x Co y M 1-x-y O2 is called, where M comprises one or more of Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg and Nb, where 0.55 ≤ x ≤ 1.0, 0 ≤ y ≤ 0.45, 0.8 ≤ a ≤ 1.2, and where the positive electrode active material has a hollow structure, wherein the inner diameter of the hollow structure is 0.3 µm to 5 µm.

[0026] Through a co-precipitation reaction, the surface of a hard template is coated with a dense layer of nickel-cobalt hydroxide, forming a compact core-shell structure. The hard template is then removed by calcination to obtain the hollow positive electrode active material. The aforementioned method for producing the positive electrode active material is simple and has low manufacturing costs. The resulting positive electrode active material has a hollow structure with an inner diameter of 0.3 µm to 5 µm, which is advantageous for the intercalation and deintercalation of lithium ions. Simultaneously, the hollow structure buffers the volume changes of the positive electrode active material during charging and discharging, thereby stabilizing the structure and improving cycle performance.

[0027] In any embodiment, the chemical formula Li appliesa Ni x Co y M 1-x-y O2: 0.9 ≤ x ≤ 1.0, 0 ≤ y ≤ 0.1, 0.8 ≤ a ≤ 1.2, optional 0.95 ≤ x ≤ 0.995, 0 ≤ y ≤ 0.05, 0.8 ≤ a ≤ 1.2.

[0028] In any embodiment, the mean diameter of the hard template medium is 0.2 µm to 3 µm, optionally 1 µm to 3 µm.

[0029] By controlling the mean diameter of the hard template medium within a suitable range, and thus controlling the inner diameter of the hollow structure of the positive electrode active material within a suitable range, both the diffusion path of the lithium ions and the stability of the hollow structure can be ensured, thereby comprehensively improving the cycle performance and rate performance of the battery.

[0030] In any embodiment, the hard template material comprises one or more carbon-nitrogen composite spheres, carbon spheres, phenolic resin microspheres and melamine resin microspheres, optionally phenolic resin spheres.

[0031] In any embodiment, in step (1) the ratio of the weight of the added hard template medium to the total weight of the elements nickel and cobalt in the mixing source is 1:20 to 3:4, or in step (1) the ratio of the weight of the added hard template medium to the total weight of the elements nickel, cobalt and M in the mixing source is 1:20 to 3:4.

[0032] By controlling the total weight of the hard template material and the elements nickel, cobalt, and magnesium in the mixing source within a suitable range, a stable and uniform coating of the hard template material's surface with the nickel-cobalt hydroxide layer is achieved. This ensures that the hollow structure has a suitable inner diameter and outer wall thickness. The positive electrode active material thus exhibits excellent structural properties, thereby improving the battery's cycle life and rate performance.

[0033] In any embodiment, the pH value of the co-precipitation reaction in step (1) is 9 to 13.

[0034] A suitable pH value for the co-precipitation reaction makes the reaction more stable and efficient, resulting in a stable and uniform coating of the hard template material's surface with the nickel-cobalt hydroxide layer. This ensures that the hollow structure has a suitable inner diameter and outer wall thickness. The positive electrode active material thus exhibits excellent structural properties, improving the battery's cycle life and rate performance.

[0035] In any embodiment, the reaction temperature of the co-precipitation reaction in step (1) is 60 °C to 85 °C.

[0036] A suitable reaction temperature for the co-precipitation reaction makes it more stable and efficient, resulting in a stable and uniform coating of the hard template material's surface with the nickel-cobalt hydroxide layer. This ensures that the hollow structure has a suitable inner diameter and outer wall thickness. The positive electrode active material thus exhibits excellent structural properties, improving the battery's cycle life and rate performance.

[0037] In any embodiment, the reaction time of the co-precipitation reaction in step (1) is 5 hours to 20 hours.

[0038] A suitable reaction time for the co-precipitation reaction makes the reaction more stable and efficient, resulting in a stable and uniform coating of the hard template material's surface with the nickel-cobalt hydroxide layer. This ensures that the hollow structure has a suitable inner diameter and outer wall thickness. The positive electrode active material thus exhibits excellent structural properties, improving the battery's cycle life and rate performance.

[0039] In any embodiment, the stirring speed of the co-precipitation reaction in step (1) is 200 rpm to 900 rpm.

[0040] A suitable stirring speed for the co-precipitation reaction makes the reaction more stable and efficient, resulting in a stable and uniform coating of the hard template material's surface with the nickel-cobalt hydroxide layer. This ensures that the hollow structure has a suitable inner diameter and outer wall thickness. The positive electrode active material thus exhibits excellent structural properties, improving the battery's cycle life and rate performance.

[0041] In any embodiment, step (1) specifically comprises the following: Preparation of a hard template solution with a mass concentration of 1 g / L to 10 g / L, a precipitating agent solution with a molar concentration of 1 mol / L to 2 mol / L, a complexing agent solution with a molar concentration of 4 mol / L to 8 mol / L and a mixed salt solution containing the element nickel and the element cobalt with a total molar concentration of 1 mol / L to 2 mol / L, wherein the mixed salt solution optionally also contains an element M; Combine and add the precipitating agent solution, the complexing agent solution, and the mixed salt solution to the hard template solution; Performing the co-precipitation reaction to preserve the precursor.

[0042] By controlling the hard template material, precipitating agent, complexing agent, and mixed salt solution within a suitable range, the co-precipitation reaction becomes more stable and efficient. During the co-precipitation reaction, the nickel-cobalt hydroxide can precipitate more slowly, stably, and densely on the surface of the hard template material, resulting in a more uniform shell layer structure. This ensures that the hollow structure has a suitable inner diameter, outer wall thickness, and Dv50 value. The positive electrode active material thus exhibits excellent structural properties, thereby increasing the battery's cycle life and rate performance.

[0043] In any embodiment, the calcination temperature in step (2) is 700 °C to 900 °C; In step (2) the calcination time is 6 hours to 18 hours.

[0044] Controlling the calcination temperature and time within a suitable range ensures that the hard template material is completely removed and a hollow structure is formed. Simultaneously, the structural stability of the positive electrode active material must be guaranteed, so that the positive electrode active material exhibits a stable hollow structure, thereby increasing the cycle life and rate performance of the battery.

[0045] A third aspect of the present application provides a positive electrode sheet, wherein the positive electrode sheet comprises the positive electrode active material according to the first aspect or the positive electrode active material produced by the method according to the second aspect.

[0046] A fourth aspect of the present application provides a secondary battery comprising the positive electrode sheet according to the third aspect.

[0047] A fifth aspect of the present application provides a power-consuming device comprising the secondary battery according to the fourth aspect. Brief description of the drawings Fig. 1 is a scanning electron microscope image of a positive electrode active material according to embodiment 4 of the present application; Fig. Figure 2 is a schematic representation of a secondary battery according to an embodiment of the present application; Fig. 3 is an exploded view of the in Fig. 2 secondary battery shown according to the embodiment of the present application; Fig. Figure 4 is a schematic representation of a battery module according to an embodiment of the present application; Fig. Figure 5 is a schematic representation of a battery pack according to an embodiment of the present application; Fig.6 is an exploded view of the in Fig. 5 battery packs shown according to the embodiment of the present application; Fig. Figure 7 is a schematic representation of a power-consuming device that uses the secondary battery as a power source according to the embodiment of the present application; Reference symbol list:

[0048] 1. Battery pack; 2. Upper housing body; 3. Lower housing body; 4. Battery module; 5. Secondary battery; 51. Housing body; 52. Electrode assembly; 53. Cover plate. Detailed descriptions

[0049] The following describes in detail embodiments of a positive electrode active material, a method for its production, a secondary battery, and a current-consuming device, which are specifically disclosed in the present application, possibly with reference to the drawings. However, an unnecessarily detailed description can be omitted. For example, a detailed description of known facts and a repeated description of essentially the same structure can be avoided. This is to prevent the following description from becoming unnecessarily lengthy, thus facilitating understanding by those skilled in the art. Furthermore, the drawings and the following description serve to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0050] The “range” disclosed in the present application is defined in terms of a lower bound and an upper bound. A given range is defined by selecting a lower bound and an upper bound. The selected lower bound and upper bound define the limits of the specific range. The ranges thus defined may or may not include the end values ​​and may be specified in any combination; that is, any lower bound can be combined with any upper bound to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, then ranges of 60 to 110 and 80 to 120 are also conceivable. Furthermore, if minimum range values ​​of 1 and 2 and maximum range values ​​of 3, 4, and 5 are listed, then all of the following ranges are conceivable: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5.In the present application, unless otherwise specified, a range of numbers "a to b" represents an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the range "0 to 5" means that all real numbers between "0 to 5" are listed therein, and "0 to 5" is simply an abbreviation for these number combinations. Furthermore, if a particular parameter is specified as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0051] Unless otherwise stated, all embodiments and optional embodiments of the present application may be combined to form a new technical solution.

[0052] Unless otherwise stated, all technical features and optional technical features of the present application may be combined to form a new technical solution.

[0053] Unless otherwise stated, all steps of the present application may be carried out sequentially or in any order, but preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out sequentially, or that it may include steps (b) and (a) carried out sequentially. Similarly, when it is mentioned that the method may further include step (c), this means that step (c) may be added in any order. For example, the method may include steps (a), (b), and (c), or steps (a), (c), and (b), or steps (c), (a), and (b), etc.

[0054] Unless otherwise stated, the terms “comprise” and “contain” used in this application may be interpreted as either open or closed. For example, the terms “comprise” and “contain” may mean that they may also include or contain other, unlisted components, or that they may only include or contain the listed components.

[0055] Unless otherwise specified, the term "or" in this application means an inclusive "or". For example, the expression "A or B" means "A, B, or both A and B". More precisely, the condition "A or B" is satisfied if any of the following conditions are true: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0056] In the prior art, a nickel-rich ternary material is among the most promising positive electrode active materials for secondary batteries due to its high theoretical specific capacity, high discharge plateau, and cost-effective availability. However, the similar ionic radii of Ni and Ni cause problems with this ternary material. +2 and Li +A serious phenomenon of cation disorder occurs, leading to a deterioration of the material's electrochemical performance. The tendency towards cation disorder increases particularly in systems with high nickel content, thus worsening the battery's cycle performance. Furthermore, interfacial side reactions during charging and discharging in lithium-ion batteries can lead to continuous decomposition of the electrolyte solution at the interface between the positive and negative electrodes, as well as phase transitions at the interface of the positive electrode active material. This causes a loss of active lithium and an increase in the lithium-ion battery's impedance, reducing the material's rate performance.Therefore, there is a need to develop a positive electrode active material with high specific capacity and excellent cycle and rate performance to meet the application requirements of next-generation electrochemical systems. [Positive electrode active material]

[0057] Against this background, the present application provides a positive electrode active material, wherein the chemical formula of the positive electrode active material is Li a Ni x Co y M 1-x-y O2 is called, where M comprises one or more of Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg and Nb, where 0.55 ≤ x ≤ 1.0, 0 ≤ y ≤ 0.45, 0.8 ≤ a ≤ 1.2, and where the positive electrode active material has a hollow structure, wherein the inner diameter d1 of the hollow structure is 0.3 µm to 5 µm.

[0058] In this document, the term "hollow structure" refers to a solid structure with an internal cavity enclosed by a distinct shell layer.

[0059] In this document, the term “inner diameter of the hollow structure” refers to the largest diameter of a circular or nearly circular cross-section of the inner cavity of the positive electrode active material.

[0060] The inner diameter of the hollow structure can be examined using any known technical method. For example, a conductive adhesive is applied to a sample stage, and a powdered sample of the positive electrode active material is evenly distributed on the conductive adhesive. The non-adherent powder is blown away with a rubber suction bulb, a gold coating is applied, and the particles of the powdered sample are sectioned using argon plasma. Scanning electron microscope images of the powdered sample are obtained using an accelerating voltage of 10 kV and an emission current of 10 mA. The inner diameter of the hollow structure is then measured according to these scanning electron microscope images. At least three samples, each with at least 50 data points, are measured.The arithmetic mean is used as a measurement of the inner diameter of the hollow structure of the sample.

[0061] In some embodiments, the value a in the chemical formula Li a Ni x Co y M 1-x-y O2 is any value from 0.8, 0.9, 1.0, 1.1, 1.2 or lies within a range consisting of any two of the above values.

[0062] In some embodiments, the value x in the chemical formula Li a Ni x Co y M 1-x-y O2 is any value from 0.55, 0.6, 0.7, 0.8, 0.9, 0.95, 0.995 or lies within a range consisting of any two of the above values.

[0063] In some embodiments, the value y in the chemical formula Li a Ni x Co y M 1-x-yO2 is any value from 0, 0.1, 0.2, 0.3, 0.4, 0.45 or lies in a range consisting of any two of the above values.

[0064] In some embodiments, the chemical formula Li applies a Ni x Co y M 1-x-y O2: 0.90 ≤ x ≤ 1.0, 0 ≤ y ≤ 0.1 and 0.8 ≤ a ≤ 1.2.

[0065] In some embodiments, the chemical formula Li applies a Ni x Co y M 1-x-y O2: 0.95 ≤ x ≤ 0.995, 0 ≤ y ≤ 0.05 and 0.8 ≤ a ≤ 1.2.

[0066] In some embodiments, the chemical formula of the positive electrode active material is Li a Ni x Co y Mn 1-x-y O2, where 0.95 ≤ x ≤ 0.995, 0 ≤ y ≤ 0.05 and 0.8 ≤ a ≤ 1.2.

[0067] In some embodiments, the chemical formula of the positive electrode active material is Li a Ni x Co y Sb 1-x-yO2, where 0.95 ≤ x ≤ 0.995, 0 ≤ y ≤ 0.05 and 0.8 ≤ a ≤ 1.2.

[0068] In some embodiments, the chemical formula of the positive electrode active material is Li a Ni x Co y O2, where 0.95 ≤ x ≤ 0.995, 0.005 ≤ y ≤ 0.05, x + y = 1 and 0.8 ≤ a ≤ 1.2.

[0069] By using the above-mentioned materials, it can be ensured that the positive electrode active material has a high capacity per gram, so that the battery has a high discharge capacity and energy density.

[0070] In some embodiments, the inner diameter d1 of the hollow structure is optionally within any of the following ranges: 0.3 µm to 0.5 µm, 0.3 µm to 0.9 µm, 0.3 µm to 1 µm, 0.3 µm to 2 µm, 0.3 µm to 3 µm, 0.3 µm to 4 µm, 0.3 µm to 5 µm, 1 µm to 2 µm, 1 µm to 3 µm, 1 µm to 4 µm, 1 µm to 5 µm, 2 µm to 3 µm, 2 µm to 4 µm, 2 µm to 5 µm, 3 µm to 4 µm, 3 µm to 5 µm or 4 µm to 5 µm.

[0071] On the one hand, the hollow structure buffers the volume changes of the positive electrode active material during charging and discharging, thus stabilizing the structure and improving cycle performance. On the other hand, the hollow positive electrode active material features more three-dimensional channels, increasing the contact area between the material and the electrolyte solution, shortening the migration distance of the lithium ions, and reducing the battery's internal resistance, resulting in excellent rate performance. Furthermore, the hollow positive electrode active material simultaneously provides more active sites for lithium ions, increasing the capacity per gram of material and improving both the discharge capacity and energy density.

[0072] In some embodiments, the inner diameter d1 of the hollow structure is 1.5 µm to 5 µm. In some embodiments, the inner diameter d1 of the hollow structure is optionally in any of the following ranges: 1.5 µm to 3 µm, 2 µm to 4 µm, 2 µm to 5 µm, 3 µm to 4 µm, 3 µm to 5 µm, or 4 µm to 5 µm.

[0073] If the inner diameter d1 of the hollow structure is within a suitable range, the migration distance of the lithium ions can be further reduced and the rate performance of the battery improved.

[0074] In some embodiments, the positive electrode active material satisfies the following relationship: 1 ≤ Dv50 / (d1 + d2) ≤ 4, where d1 in µm denotes the inner diameter of the hollow structure, d2 in µm denotes the outer wall thickness of the hollow structure, and Dv50 in µm denotes the Dv50 value of the positive electrode active material.

[0075] In some embodiments, the positive electrode active material satisfies any one of the following relationships: 1 ≤ Dv50 / (d1 + d2) ≤ 2, 1 ≤ Dv50 / (d1 + d2) ≤ 3, 1 ≤ Dv50 / (d1 + d2) ≤ 4, 2 ≤ Dv50 / (d1 + d2) ≤ 3, 2 ≤ Dv50 / (d1 + d2) ≤ 4 or 3 ≤ Dv50 / (d1 + d2) ≤ 4, where d1 in µm denotes the inner diameter of the hollow structure, d2 in µm denotes the outer wall thickness of the hollow structure, and Dv50 in µm denotes the Dv50 value of the positive electrode active material.

[0076] In this document, the term "outer wall thickness of the hollow structure" refers to the thickness of the outer shell layer of the hollow structure.

[0077] The outer wall thickness of the hollow structure can be tested using any known technical method. For example, a conductive adhesive is applied to a sample stage, and a powdered sample of the positive electrode active material is evenly distributed on the adhesive. The non-adherent powder is blown away with a rubber suction bulb, a gold coating is applied, and the powdered sample particles are sectioned using argon plasma. Scanning electron microscope images of the powdered sample are obtained using an accelerating voltage of 10 kV and an emission current of 10 mA. The outer wall thickness of the hollow structure is then measured based on these scanning electron microscope images. At least three samples, each with at least 50 data points, are measured.The arithmetic mean is used as a measurement of the outer wall thickness of the hollow structure of the sample.

[0078] In this document, the term "Dv50" refers to the mean particle size of the positive electrode active material. More precisely, Dv50 represents the particle size of the positive electrode active material at which the cumulative volume reaches 50% in a volume-based particle size distribution, starting from the side of the small particle size.

[0079] The Dv50 value of the positive electrode active material can be tested using any method known in the art. For example, the Dv50 value of the positive electrode active material can be measured according to the method specified in GB / T19077-2016.

[0080] The Dv50 value of the positive electrode active material, the inner diameter d1 of the hollow structure, and the outer wall thickness d2 are essential parameters for the structure of the positive electrode active material and influence its structural properties. If the Dv50 value of the positive electrode active material, the inner diameter d1 of the hollow structure, and the outer wall thickness d2 are within a suitable range, the material exhibits a high number of active sites for lithium ions, which improves the capacity per gram of the material. This increases the energy density of the material and simultaneously improves its structural stability. The phenomenon of lithium-nickel disorder is effectively reduced, and the migration rates of lithium ions and electrons are significantly increased, thus improving the rate performance of the material.

[0081] By controlling the Dv50 value of the positive electrode active material, the inner diameter d1 and the outer wall thickness d2 of the hollow structure such that 1 ≤ Dv50 / (d1 + d2) ≤ 4, the energy density and rate performance of the battery can be improved.

[0082] In some embodiments, the outer wall thickness d2 of the hollow structure is 3 µm to 10 µm. In some embodiments, the outer wall thickness d2 of the hollow structure optionally lies within any of the following ranges: 3 µm to 4 µm, 3 µm to 5 µm, 3 µm to 6 µm, 3 µm to 7 µm, 3 µm to 8 µm, 3 µm to 9 µm, 3 µm to 10 µm, 4 µm to 5 µm, 4 µm to 6 µm, 4 µm to 7 µm, 4 µm to 8 µm, 4 µm to 9 µm, 4 µm to 10 µm, 5 µm to 6 µm, 5 µm to 7 µm, 5 µm to 8 µm, 5 µm to 9 µm, 5 µm to 10 µm, 6 µm to 7 µm, 6 µm to 8 µm, 6 µm to 9 µm, 6 µm to 10 µm, 7 µm to 8 µm, 7 µm to 9 µm, 7 µm to 10 µm, 8 µm to 9 µm, 8 µm to 10 µm or 9 µm to 10 µm.

[0083] By controlling the outer wall thickness d2 of the hollow structure in a suitable area, the structural stability of the material can be increased, and the battery thus exhibits a high discharge capacity and energy density as well as excellent rate and cycle performance, which comprehensively improves the electrochemical performance of the battery.

[0084] In some embodiments, the outer wall thickness d2 of the hollow structure is 3 µm to 7 µm. In some embodiments, the outer wall thickness d2 of the hollow structure is optionally in any of the following ranges: 3 µm to 4 µm, 3 µm to 5 µm, 3 µm to 6 µm, 3 µm to 7 µm, 4 µm to 5 µm, 4 µm to 6 µm, 4 µm to 7 µm, 5 µm to 6 µm, 5 µm to 7 µm, or 6 µm to 7 µm.

[0085] If the outer wall thickness of the hollow structure is within a suitable range, the cycle performance and rate performance of the battery can be further increased.

[0086] In some embodiments, the Dv50 value of the positive electrode active material is 5 µm to 15 µm. In some embodiments, the Dv50 value of the positive electrode active material is optionally in any of the following ranges: 5 µm to 9 µm, 5 µm to 10 µm, 5 µm to 15 µm, 9 µm to 10 µm, 9 µm to 15 µm, or 10 µm to 15 µm.

[0087] Particles of different sizes have different surface areas and therefore a different number of reactive sites. Consequently, particle size influences the rate of deintercalation and intercalation of ions, and thus the capacity per gram of material. By controlling the Dv50 value of the positive electrode active material within a suitable range, the energy density and rate of power of the battery can be increased.

[0088] In some embodiments, the Dv50 value of the positive electrode active material is 8 µm to 10 µm. In some embodiments, the Dv50 value of the positive electrode active material lies in any of the following ranges: 8 µm to 9 µm, 8 µm to 10 µm, or 9 µm to 10 µm.

[0089] By controlling the Dv50 value of the positive electrode active material within a suitable range, the energy density and rate performance of the battery can be further increased.

[0090] In some embodiments, the porosity of the positive electrode active material is 0 to 20%. In some embodiments, the porosity of the positive electrode active material is optionally in any of the following ranges: 0 to 5%, 0 to 10%, 0 to 15%, 0 to 20%, 5% to 10%, 5% to 15%, 5% to 20%, 10% to 15%, 10% to 20%, or 15% to 20%.

[0091] In this document, the term “porosity” refers to the ratio of the pore volume in the positive electrode active material to the total volume of the positive electrode active material.

[0092] The porosity of the positive electrode active material can be tested using any method known in the industry. As an example, measurement is carried out using the gas displacement method according to GB / T24586. The porosity = (VI - V2) / V1 * 100%, where V1 is the apparent volume of the sample and V2 is the actual volume of the sample.

[0093] By controlling the porosity of the positive electrode active material within a suitable range, wetting by the electrolyte solution is promoted, thus enabling sufficient contact between the positive electrode active material and the electrolyte solution and shortening the transport path of the lithium ions. This results in the battery exhibiting high discharge capacity and energy density, as well as excellent rate and cycle performance, thereby comprehensively improving the battery's electrochemical performance.

[0094] In some embodiments, the porosity of the positive electrode active material is 2% to 15%. In some embodiments, the porosity of the positive electrode active material is optionally in any of the following ranges: 2% to 5%, 2% to 10%, 2% to 15%, 5% to 10%, 5% to 15%, or 10% to 15%.

[0095] By controlling the porosity of the positive electrode active material within a suitable range, the discharge capacity and energy density of the battery can be further increased, as well as the cycle performance and rate performance of the battery.

[0096] In some embodiments, the specific surface area of ​​the positive electrode active material is 0.4 m². 2 / g up to 1.4 m 2 / g. In some embodiments, the specific surface area of ​​the positive electrode active material is optionally located in any of the following ranges: 0.4 m² 2 / g up to 0.7 m 2 / g, 0.4 m 2 / g up to 0.9 m 2 / g, 0.5 m 2 / g up to 0.7 m 2 / g, 0.5 m 2 / g up to 0.9 m 2 / g, 0.5 m 2 / g up to 1.1 m 2 / g, 0.7 m 2 / g up to 0.9 m 2 / g, 0.7 m 2 / g up to 1.1 m 2 / g or 0.9 m 2 / g up to 1.1 m 2 / G.

[0097] The specific surface area of ​​the positive electrode active material can be determined using any method known in the industry. For example, reference can be made to GB / T 19587-2017 "Determination of the specific surface area of ​​solids by gas adsorption according to the BET method". The determination is carried out using the TriStar II 3020 instrument. The positive electrode active material is dispersed in a dispersant (ethanol), treated with ultrasound for 30 minutes, the resulting material is dried in a vacuum drying oven, and finally, the specific surface area of ​​the positive electrode active material is measured using a specific surface area measuring device.

[0098] The larger the specific surface area of ​​the positive electrode active material, the more active sites it has, the faster the exchange between the positive electrode active material and the electrons occurs, and the better the battery's kinetic performance. However, too many active sites increase side reactions between the positive electrode active material and the electrolyte solution, thus reducing the battery's cycle life. Conversely, too few active sites lead to a reduction in chemical reactions within the battery system, resulting in lower battery capacity and poorer cycle life.

[0099] By controlling the specific surface area of ​​the positive electrode active material in a suitable area, the battery exhibits a high discharge capacity and energy density, as well as excellent rate and cycle performance, thereby comprehensively improving the electrochemical performance of the battery.

[0100] In some embodiments, the SPAN value of the positive electrode active material is 1 to 1.5. In some embodiments, the SPAN value of the positive electrode active material is optionally in any of the following ranges: 1 to 1.1, 1 to 1.2, 1 to 1.3, 1 to 1.4, 1 to 1.5, 1.1 to 1.2, 1.1 to 1.3, 1.1 to 1.4, 1.1 to 1.5, 1.2 to 1.3, 1.2 to 1.4, 1.2 to 1.5, 1.3 to 1.4, 1.3 to 1.5, or 1.4 to 1.5.

[0101] In this document, the term "SPAN" refers to the distribution range. SPAN is calculated using the formula (Dv90 - Dv10) / Dv50 and represents the particle distribution of the positive electrode active material. Here, Dv50 represents the particle size of the positive electrode active material at which the cumulative volume reaches 50% in a volume-based particle size distribution, starting from the side of the smallest particle size; Dv10 represents the particle size of the positive electrode active material at which the cumulative volume reaches 10% in a volume-based particle size distribution, starting from the side of the smallest particle size; and Dv90 represents the particle size of the positive electrode active material at which the cumulative volume reaches 90% in a volume-based particle size distribution, starting from the side of the smallest particle size.

[0102] The values ​​Dv50, Dv10 and Dv90 of the positive electrode active material are measured according to the method specified in GB / T 19077-2016, from which the SPAN value of the positive electrode active material is then calculated.

[0103] If SPAN is kept within a relatively wide range, the compaction density of the material as well as the discharge capacity of the battery can be increased.

[0104] In some embodiments, the SPAN value of the positive electrode active material is 1.2 to 1.4. In some embodiments, the SPAN value of the positive electrode active material is optionally in any of the following ranges: 1.2 to 1.3, 1.2 to 1.4, or 1.3 to 1.4.

[0105] When SPAN is kept within a relatively wide range, particles of varying sizes are present, thus preventing particle cracking during the battery cycle process, resulting in excellent cycle performance; the synthesized precursor particles are of a non-uniform size, and the particles are in close contact with each other, improving the transport rate of lithium ions, resulting in excellent rate performance.

[0106] By controlling the SPAN value of the positive electrode active material within a suitable range, the cycle performance and rate performance of the battery can be ensured, thereby comprehensively improving the electrochemical performance of the battery.

[0107] In some embodiments, the area of ​​the (010) crystal plane of the positive electrode active material is greater than or equal to 6 µm². 2 .

[0108] In some embodiments, the area of ​​the (010) crystal plane of the positive electrode active material is greater than or equal to any of the following values: 6 µm 2 , 20 µm 2 , 50 µm 2 , 100 µm 2 , 150 µm 2 , 200 µm 2 , 240 µm 2 or 250 µm 2 .

[0109] The area of ​​the (010) crystal plane of the positive electrode active material can be tested using any method known in the art. As an example, the area of ​​the (010) crystal plane is measured using an X-ray powder diffractometer (XRD, instrument type: Bruker D8 ADVANCE) with Cu Kα as the target material; the voltage is 40 kV and the current is 40 mA, the scan angle range is between 5° and 80°, the step size is 0.00836° and the time per step is 0.3 seconds.

[0110] The (010) crystal plane is the preferred plane for lithium ion transport. If the positive electrode active material has a large area of ​​the (010) crystal plane, it has many reactive sites for lithium ions, resulting in excellent kinetic performance of the battery.

[0111] By controlling the area of ​​the (010) crystal plane of the positive electrode active material to be greater than or equal to 6 µm 2 The battery exhibits a high discharge capacity and energy density, as well as excellent rate and cycle performance, thereby comprehensively improving the electrochemical performance of the battery.

[0112] In some embodiments, the primary particle size of the positive electrode active material is 0.1 µm to 0.8 µm. In some embodiments, the primary particle size of the positive electrode active material is optionally within any of the following ranges: 0.1 µm to 0.2 µm, 0.1 µm to 0.3 µm, 0.1 µm to 0.4 µm, 0.1 µm to 0.5 µm, 0.1 µm to 0.6 µm, 0.1 µm to 0.7 µm, 0.1 µm to 0.8 µm, 0.2 µm to 0.3 µm, 0.2 µm to 0.4 µm, 0.2 µm to 0.5 µm, 0.2 µm to 0.6 µm, 0.2 µm to 0.7 µm, 0.2 µm to 0.8 µm, 0.3 µm to 0.4 µm, 0.3 µm to 0.5 µm, 0.3 µm to 0.6 µm, 0.3 µm to 0.7 µm, 0.3 µm to 0.8 µm, 0.4 µm to 0.5 µm, 0.4 µm to 0.6 µm, 0.4 µm to 0.7 µm, 0.4 µm to 0.8 µm, 0.5 µm to 0.6 µm, 0.5 µm to 0.7 µm, 0.5 µm to 0.8 µm, 0.6 µm to 0.7 µm, 0.6 µm to 0.8 µm or 0.7 µm to 0.8 µm.

[0113] In this document, the term "primary particles" refers to the particles of the positive electrode active material prior to agglomeration.

[0114] The primary particle size of the positive electrode active material can be checked using any method known in the art. As an example, after 500x scanning electron microscopy, 200 to 600 fully formed and unobstructed primary particles of the positive electrode active material are randomly selected from the electron micrograph, and the mean of the largest diameter of the primary particles in the microscopic image is recorded as the average particle size.

[0115] By controlling the primary particle size of the positive electrode active material within a suitable range, the diffusion path of the lithium ions is shortened and the intercalation and deintercalation rate of the lithium ions is accelerated, thereby improving the discharge capacity and energy density of the battery as well as the rate performance of the battery.

[0116] In some embodiments, the primary particle size of the positive electrode active material is 0.15 µm to 0.3 µm. In some embodiments, the primary particle size of the positive electrode active material is optionally in any of the following ranges: 0.15 µm to 0.2 µm, 0.15 µm to 0.3 µm, or 0.2 µm to 0.3 µm.

[0117] By controlling the primary particle size of the positive electrode active material within a suitable range, the primary particles exhibit excellent structural stability. During the cyclic charging and discharging process, the primary particles can maintain their complete structure despite repeated deintercalation and intercalation of lithium ions. This reduces the phenomenon of transition metals leaching from the primary particles and dissolving into the electrolyte solution, thus improving the battery's cycle stability.

[0118] In some embodiments, the capacity per gram of the positive electrode active material is 238 mAh / g to 250 mAh / g.

[0119] The capacitance per gram of positive electrode active material can be tested using any method known in engineering. For example, a button cell is charged at 25 °C and normal pressure with a constant current of 0.02 C-rate to a voltage of 3.5 V, then with a constant current of 0.1 C-rate to a voltage of 4.3 V, and then with a constant voltage of 4.3 V until the current drops to 0.05 C. The specific charge capacitance recorded at this point corresponds to the first lithiation capacitance. The cell is then discharged with a constant current of 0.1 C-rate to a voltage of 2.5 V, and the specific discharge capacitance recorded at this point corresponds to the first lithiation capacitance. The capacitance per gram of positive electrode active material corresponds to the first lithiation capacitance.

[0120] The present application further provides a method for producing a positive electrode active material, comprising step (1) and step (2): Step (1): Mixing a mixture source containing a nickel source and a cobalt source with a hard template agent, a complexing agent and a precipitating agent and carrying out a co-precipitation reaction to obtain a precursor, wherein the mixture source optionally contains an M source, Step (2): Calcining the precursor with a lithium source to preserve the positive electrode active material, where the chemical formula of the positive electrode active material Li a Ni x Co y M 1-x-y O2 is called, where M comprises one or more of Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg and Nb, where 0.55 ≤ x ≤ 1.0, 0 ≤ y ≤ 0.45, 0.8 ≤ a ≤ 1.2, and where the positive electrode active material has a hollow structure, wherein the inner diameter of the hollow structure is 0.3 µm to 5 µm.

[0121] In this document, the term "co-precipitation reaction" refers to a precipitation reaction in which a metal solution, a precipitating agent and a complexing agent react together at a specific temperature.

[0122] In some embodiments, the M source is a manganese source or an antimony source.

[0123] In some embodiments, the process for producing the positive electrode active material comprises step (1) and step (2): Step (1): Mixing a mixture source containing a nickel source and a cobalt source with a hard template agent, a complexing agent and a precipitating agent, and carrying out a co-precipitation reaction to obtain a precursor. Step (2): Calcining the precursor with a lithium source to preserve the positive electrode active material.

[0124] In some embodiments, the nickel source comprises one or more of nickel sulfate, nickel chloride, nickel nitrate or nickel acetate.

[0125] In some embodiments, the cobalt source comprises one or more of cobalt sulfate, cobalt chloride, cobalt nitrate or cobalt acetate.

[0126] In some embodiments, the manganese source comprises one or more of manganese sulfate, manganese chloride, manganese nitrate, or manganese acetate.

[0127] In some embodiments, the antimony source comprises one or more of antimony sulfate, antimony chloride, antimony nitrate, or antimony acetate.

[0128] Through a co-precipitation reaction, the surface of a hard template is coated with a dense layer of nickel-cobalt hydroxide, forming a compact core-shell structure. The hard template is then removed by calcination to obtain the hollow positive electrode active material. The aforementioned method for producing the positive electrode active material is simple and has low manufacturing costs. The resulting positive electrode active material has a hollow structure with an inner diameter of 0.3 µm to 5 µm, which is advantageous for the intercalation and deintercalation of lithium ions. Simultaneously, the hollow structure buffers the volume changes of the positive electrode active material during charging and discharging, thereby stabilizing the structure and improving cycle performance.

[0129] In some embodiments, the chemical formula Li applies aNi x Co y M 1-x-y O2: 0.9 ≤ x ≤ 1.0, 0 ≤ y ≤ 0.1 and 0.8 ≤ a ≤ 1.2.

[0130] In some embodiments, the chemical formula Li applies a Ni x Co y M 1-x-y O2: 0.95 ≤ x ≤ 0.995, 0 ≤ y ≤ 0.05 and 0.8 ≤ a ≤ 1.2.

[0131] In some embodiments, the mean diameter of the hard template medium is 0.2 µm to 3 µm. In some embodiments, the mean diameter of the hard template medium is optionally in any of the following ranges: 0.2 µm to 1 µm, 0.2 µm to 2 µm, 0.2 µm to 3 µm, 1 µm to 2 µm, 1 µm to 3 µm, or 2 µm to 3 µm.

[0132] In some embodiments, the mean diameter of the hard template medium is 1 µm to 3 µm. In some embodiments, the mean diameter of the hard template medium is optionally in any of the following ranges: 1 µm to 2 µm, 1 µm to 3 µm, or 2 µm to 3 µm.

[0133] By controlling the mean diameter of the hard template medium within a suitable range, and thus controlling the inner diameter of the hollow structure of the positive electrode active material within a suitable range, both the diffusion path of the lithium ions and the stability of the hollow structure can be ensured, thereby comprehensively improving the cycle performance and rate performance of the battery.

[0134] In some embodiments, the hard template material comprises one or more carbon-nitrogen composite spheres, carbon spheres, phenolic resin microspheres, or melamine resin microspheres.

[0135] In some embodiments, the hard template material comprises phenolic resin spheres.

[0136] A suitable hard template material exhibits excellent adsorption capacity, allowing a dense layer of nickel-cobalt hydroxide to form on its surface during the co-precipitation reaction. This results in the positive electrode active material possessing excellent structural properties, thereby improving the battery's cycle life and rate performance.

[0137] In some embodiments, in step (1) the ratio of the weight of the added hard template medium to the total weight of the elements nickel and cobalt in the mixing source is 1:20 to 3:4,

[0138] In some embodiments, in step (1) the ratio of the weight of the added hard template medium to the total weight of the elements nickel, cobalt and M in the mixing source is 1:20 to 3:4.

[0139] In some embodiments, in step (1) the ratio of the weight of the added hard template medium to the total weight of the elements nickel and cobalt in the mixing source is any value from 1:20, 1:15, 1:10, 1:5, 1:4, 2:4, 3:4 or lies in a range consisting of any two of the above values.

[0140] In some embodiments, in step (1) the ratio of the weight of the added hard template medium to the total weight of the elements nickel, cobalt and M in the mixing source is any value from 1:20, 1:15, 1:10, 1:5, 1:4, 2:4, 3:4 or lies in a range consisting of any two of the above values.

[0141] In some embodiments, in step (1) the ratio of the weight of the added hard template medium to the total weight of the elements nickel, cobalt and manganese in the mixing source is any value from 1:20, 1:15, 1:10, 1:5, 1:4, 2:4, 3:4 or lies in a range consisting of any two of the above values.

[0142] By controlling the total weight of the hard template material and the elements nickel, cobalt, and magnesium in the mixing source within a suitable range, a stable and uniform coating of the hard template material's surface with the nickel-cobalt hydroxide layer is achieved. This ensures that the hollow structure has a suitable inner diameter and outer wall thickness. The positive electrode active material thus exhibits excellent structural properties, thereby improving the battery's cycle life and rate performance.

[0143] In some embodiments, the pH value of the co-precipitation reaction in step (1) is 9 to 13.

[0144] In some embodiments, the pH value is any value from 9, 10, 11, 12, 13, or lies within a range consisting of any two of the above values.

[0145] A suitable pH value for the co-precipitation reaction makes the reaction more stable and efficient, resulting in a stable and uniform coating of the hard template material's surface with the nickel-cobalt hydroxide layer. This ensures that the hollow structure has a suitable inner diameter and outer wall thickness. The positive electrode active material thus exhibits excellent structural properties, improving the battery's cycle life and rate performance.

[0146] In some embodiments, the reaction temperature of the co-precipitation reaction in step (1) is 60 °C to 85 °C.

[0147] In some embodiments, the reaction temperature is any value from 60 °C, 70 °C, 80 °C, 85 °C or lies in a range consisting of any two of the above values.

[0148] A suitable reaction temperature for the co-precipitation reaction makes it more stable and efficient, resulting in a stable and uniform coating of the hard template material's surface with the nickel-cobalt hydroxide layer. This ensures that the hollow structure has a suitable inner diameter and outer wall thickness. The positive electrode active material thus exhibits excellent structural properties, improving the battery's cycle life and rate performance.

[0149] In some embodiments, the reaction time of the co-precipitation reaction in step (1) is 5 hours to 20 hours.

[0150] In some embodiments, the reaction time is any value from 5 hours, 10 hours, 15 hours, 20 hours, or lies in a range consisting of any two of the above values.

[0151] A suitable reaction time for the co-precipitation reaction makes the reaction more stable and efficient, resulting in a stable and uniform coating of the hard template material's surface with the nickel-cobalt hydroxide layer. This ensures that the hollow structure has a suitable inner diameter and outer wall thickness. The positive electrode active material thus exhibits excellent structural properties, improving the battery's cycle life and rate performance.

[0152] In some embodiments, the stirring speed of the co-precipitation reaction in step (1) is 200 rpm to 900 rpm.

[0153] In some embodiments, the stirring speed of the reaction is any value from 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, or lies in a range consisting of any two of the above values.

[0154] A suitable stirring speed for the co-precipitation reaction makes the reaction more stable and efficient, resulting in a stable and uniform coating of the hard template material's surface with the nickel-cobalt hydroxide layer. This ensures that the hollow structure has a suitable inner diameter and outer wall thickness. The positive electrode active material thus exhibits excellent structural properties, improving the battery's cycle life and rate performance.

[0155] In some embodiments, step (1) specifically includes the following:

[0156] Preparation of a hard template solution with a mass concentration of 1 g / L to 10 g / L, a precipitating agent solution with a molar concentration of 1 mol / L to 2 mol / L, a complexing agent solution with a molar concentration of 4 mol / L to 8 mol / L and a mixed salt solution containing the element nickel and the element cobalt with a total molar concentration of 1 mol / L to 2 mol / L, wherein the mixed salt solution optionally also contains an element M;

[0157] Combine and add the precipitating agent solution, the complexing agent solution, and the mixed salt solution to the hard template solution;

[0158] Performing the co-precipitation reaction to preserve the precursor.

[0159] In some embodiments, the precipitating agent comprises one or more of sodium hydroxide, sodium carbonate, sodium hydrogen carbonate and ammonium hydrogen carbonate, optionally ammonium hydrogen carbonate.

[0160] In some embodiments, the complexing agent comprises one or more of ammonia water, lactic acid and polyvinylpyrrolidone, optionally ammonia water.

[0161] In some embodiments, the mass concentration of the hard template agent solution is any value from 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L, 10 g / L or lies in a range consisting of any two of the above values.

[0162] In some embodiments, the molar concentration of the precipitating agent solution is any value from 1 mol / L, 1.5 mol / L, 2 mol / L or lies in a range consisting of any two of the above values.

[0163] In some embodiments, the molar concentration of the complexing agent solution is any value from 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L or lies in a range consisting of any two of the above values.

[0164] In some embodiments, the molar concentration of the mixed salt is any value from 1 mol / L, 1.5 mol / L, 2 mol / L or lies in a range consisting of any two of the above values.

[0165] By controlling the hard template material, precipitating agent, complexing agent, and mixed salt solution within a suitable range, the co-precipitation reaction becomes more stable and efficient. During the co-precipitation reaction, the nickel-cobalt hydroxide can precipitate more slowly, stably, and densely on the surface of the hard template material, resulting in a more uniform shell layer structure. This ensures that the hollow structure has a suitable inner diameter, outer wall thickness, and Dv50 value. The positive electrode active material thus exhibits excellent structural properties, thereby increasing the battery's cycle life and rate performance.

[0166] In some embodiments, the calcination temperature in step (2) is 700 °C to 900 °C;

[0167] In step (2) the calcination time is 6 hours to 18 hours.

[0168] In some embodiments, in step (2) the calcination temperature is any value from 700 °C, 800 °C, 900 °C or is in a range consisting of any two of the above values.

[0169] In some embodiments, in step (2) the calcination time is any value from 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours or lies in a range consisting of any two of the above values.

[0170] Controlling the calcination temperature and time within a suitable range ensures that the hard template material is completely removed and a hollow structure is formed. Simultaneously, the structural stability of the positive electrode active material must be guaranteed, so that the positive electrode active material exhibits a stable hollow structure, thereby increasing the cycle life and rate performance of the battery. [Positive electrode sheet]

[0171] The positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer formed on at least a part of the surface of the positive electrode current collector, and the positive electrode film layer comprises the positive electrode active material in some embodiments.

[0172] In some embodiments, the areal density of the positive electrode film layer is 24 mg / cm². 2up to 46 mg / cm² 2 .

[0173] The coating area density of the positive electrode film layer is determined by measuring the coating weight (in g) of the one-sided positive electrode film layer and the coating area (in cm²). 2 ) of the one-sided positive electrode film layer (number of measuring points > 14). Specifically: Coating area density of the positive electrode film layer = Coating weight (in g) of the one-sided positive electrode film layer / Coating area (in cm²). 2 ) of the one-sided positive electrode film layer.

[0174] The positive electrode film layer can further comprise a conductive material to improve the conductivity of the positive electrode. Optionally, the conductive material is one or more of the following: Super P, acetylene carbon black, carbon black, Ketjen carbon black, carbon dots, carbon nanotubes, graphite, graphene, and carbon nanofibers.

[0175] The positive electrode film layer may further comprise a binder to firmly bind the positive electrode active material and, optionally, the conductive medium to the positive electrode current collector. Optionally, the binder is at least one of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), polyvinyl alcohol (PVA), ethylene-vinyl acetate copolymer (EVA), styrene-butadiene rubber (SBR), carboxymethylcellulose (CMC), sodium alginate (SA), polymethacrylic acid (PMA), and carboxymethyl chitosan (CMCS).

[0176] The positive electrode current collector can be a conductive carbon sheet, a metal foil, a carbon-coated metal foil, a porous metal plate, or a composite current collector. Optionally, the conductive carbon material of the conductive carbon sheet can be one or more of Super P, carbon black, Ketjen carbon black, carbon dots, carbon nanotubes, graphite, graphene, and carbon nanofibers. The metal material of the metal foil, the carbon-coated metal foil, and the porous metal plate is each independently selected from at least one of copper, aluminum, nickel, and stainless steel. The composite current collector can be formed by combining a metal foil with a polymer base film.

[0177] In some embodiments, the positive electrode sheet can be produced as follows: The above-mentioned components for producing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder, and any other components, are dispersed in a solvent (such as N-methyl-2-pyrrolidone) to form a positive electrode paste; the positive electrode current collector is coated with the positive electrode paste, and after drying, cold pressing, and other processes, the positive electrode sheet can be obtained. [Negative electrode sheet]

[0178] The negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector. The negative electrode film layer comprises a negative electrode active material.

[0179] As an example, the negative electrode current collector has two opposing surfaces in its own thickness direction, with the negative electrode film layer being arranged on one or both of these opposing surfaces of the negative electrode current collector.

[0180] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. For example, copper foil can be used as the metal foil. The composite current collector can comprise a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on the polymer material substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0181] In some embodiments, the negative electrode active material can be a negative electrode material known in the art for a battery. For example, the negative electrode active material can comprise at least one of synthetic graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, and the like. The silicon-based material can be selected from at least one of elemental silicon, silicon oxide compound, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material can be selected from at least one of elemental tin, tin oxide compound, and tin alloy. However, the present application is not limited to these materials, and other conventional materials suitable for use as a negative electrode material for a battery can also be used.These negative electrode materials can be used alone or in combination with two or more.

[0182] In some embodiments, the capacity per gram of the negative electrode active material is 600 mAh / g to 2500 mAh / g.

[0183] In some embodiments, the negative electrode active material comprises silicon monoxide.

[0184] In some embodiments, the mass fraction of silicon monoxide, based on the total mass of the negative electrode active material, is 20% to 100%, optionally 50% to 100%.

[0185] In some embodiments, the negative electrode film layer optionally comprises a binder. The binder can be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0186] In some embodiments, the negative electrode film layer optionally comprises a conductive material. The conductive material can be selected from at least one of superconducting carbon, carbon black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0187] In some embodiments, the negative electrode film layer optionally also includes other auxiliary materials, such as a thickening agent (such as sodium carboxymethylcellulose (CMC-Na)).

[0188] In some embodiments, the negative electrode sheet can be produced as follows: The above-mentioned components for producing the negative electrode film layer, such as the negative electrode material, the conductive agent, the binder, and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode paste; the negative electrode current collector is coated with the negative electrode paste, and after drying, cold pressing, and other processes, the negative electrode sheet can be obtained. [Electrolyte]

[0189] The electrolyte serves to conduct ions between the positive and negative electrode sheets. This application does not impose any specific restrictions regarding the type of electrolyte, and the type can be selected according to the requirements. For example, the electrolyte can be liquid, gel-like, or completely solid.

[0190] In some embodiments, the electrolyte is in the form of an electrolyte solution. The electrolyte solution comprises an electrolyte salt and a solvent.

[0191] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorobisoxalatophosphate and lithium tetrafluoro(oxalato)phosphate.

[0192] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0193] In some embodiments, the electrolyte solution optionally includes an additive. For example, the additive may include a negative electrode film-forming additive, a positive electrode film-forming additive, and an additive that can improve certain battery performance characteristics, such as an additive that improves the battery's overcharge behavior, an additive that improves the battery's high-temperature performance, and an additive that improves the battery's low-temperature performance. [Separator]

[0194] In some embodiments, the secondary battery also includes a separator. The present application does not impose any specific restrictions on the type of separator, and any known separator with good chemical and mechanical stability and a porous structure can be used.

[0195] In some embodiments, the separator material can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film without any particular restriction. If the separator is a multi-layer composite film, the materials of each layer can be the same or different without any particular restriction.

[0196] In some embodiments, the positive electrode sheet, the negative electrode sheet and the separator can be formed into an electrode arrangement by a winding or stacking process.

[0197] In some embodiments, the secondary battery may include an outer casing. This outer casing may be used to encapsulate the aforementioned electrode arrangement and the electrolyte.

[0198] In some embodiments, the outer packaging of the secondary battery can be a rigid casing, such as a hard plastic casing, an aluminum casing, a steel casing, etc. The outer packaging of the secondary battery can also be a soft casing, such as a bag-like soft casing. The material of the soft casing can be plastic. Examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0199] The present application does not impose any special restrictions regarding the shape of the secondary battery; it may be cylindrical, rectangular, or any other shape. For example, shows Fig. 2 as an example a secondary battery 5 with a square structure.

[0200] In some embodiments, the energy density of the secondary battery is 380 Wh / kg to 500 Wh / kg.

[0201] In some embodiments, the outer packaging, referring to Fig.3, comprising a housing body 51 and a cover plate 53. The housing body 51 may comprise a base plate and a side plate connected to the base plate, the base plate and the side plate forming a receiving chamber. The housing body 51 has an opening that communicates with the receiving chamber, and the cover plate 53 may cover the opening to close the receiving chamber. The positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly 52 by a winding or stacking process. The electrode assembly 52 is encapsulated in the receiving chamber. The electrolyte solution is impregnated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the secondary battery 5 may be one or more; the person skilled in the art may choose according to specific actual requirements.

[0202] In some embodiments, secondary batteries can be assembled into a battery module. The number of secondary batteries contained in the battery module can be one or more. The exact number can be selected by a person skilled in the art depending on the application and capacity of the battery module.

[0203] Fig. Figure 4 shows, as an example, a battery module 4. Referring to Fig. 4. Several secondary batteries 5 can be arranged in series along the length of the battery module 4. Of course, other arrangements are also possible. Furthermore, the multiple secondary batteries 5 can be secured by fastening elements.

[0204] Optionally, the battery module 4 can also include a housing with a receiving space, in which the multiple secondary batteries 5 are received.

[0205] In some embodiments, the above-mentioned battery module can also be assembled into a battery pack, wherein the number of battery modules contained in the battery pack can be one or more; the person skilled in the art can select a specific number depending on the application and capacity of the battery pack.

[0206] The Fig. 5 and Fig. Figure 6 shows a battery pack as an example. 1. Referring to the Fig. 5 and Fig. 6. The battery pack 1 can comprise a battery box and several battery modules 4 arranged therein. The battery box comprises an upper box body 2 and a lower box body 3; the upper box body 2 can cover the lower box body 3 and form an enclosed space for receiving the battery modules 4. The several battery modules 4 can be arranged in any way within the battery box.

[0207] Furthermore, the present application provides a power-consuming device comprising at least one of the secondary battery, battery module, and battery pack provided by the present application. The secondary battery, battery module, or battery pack can be used as a power source for the power-consuming device or as an energy storage device for the power-consuming device. The power-consuming devices may include, but are not limited to, mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0208] Depending on its usage requirements, the secondary battery, battery module or battery pack can be selected as the power-consuming device.

[0209] Fig. Figure 7 shows an example of a power-consuming device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the power-consuming device's requirements for high performance and high energy density of the secondary battery, a battery pack or battery module can be used.

[0210] As another example, the device could be a mobile phone, a tablet, a laptop, etc. The device typically needs to be lightweight and thin and can use a secondary battery as a power source. Example of implementation

[0211] The following are exemplary embodiments of the present application. These embodiments are for illustrative purposes only and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the technical literature or product instructions must be followed. All reagents and instruments used without manufacturer information are commercially available products. I. Manufacturing Method Example 11) Production of a positive electrode active material

[0212] A nickel-cobalt-manganese solution with a molar ratio of nickel, cobalt, and manganese of 97:2:1 was prepared, with the concentration adjusted to 2 mol / L. Nickel sulfate, cobalt sulfate, and manganese sulfate, respectively, were used as soluble nickel, cobalt sulfate, and manganese raw materials. A sodium hydroxide solution with a concentration of 2 mol / L was prepared. An ammonia solution with a concentration of 6 mol / L was prepared. A carbon sphere dispersion with a mass concentration of 10 g / L was prepared, placed in a reaction vessel, and stirred at 800 rpm for 120 minutes until a uniform dispersion was achieved. Carbon sphere specifications: diameter of 0.25 µm.

[0213] The aforementioned nickel-cobalt-manganese solution, sodium hydroxide solution, and ammonia solution were simultaneously added to the reaction vessel to carry out a co-precipitation reaction. The rotational speed was controlled at 800 rpm, the temperature at 60 °C, and the reaction time at 6 hours. The flow rates of the three solutions were regulated so that the sodium hydroxide solution flowed at 0.5 L / min, the ammonia solution at 0.7 L / min, and the nickel-cobalt-manganese solution at 0.2 L / min. The pH of the system was controlled at 10.8. The ratio of the weight of the carbon spheres to the total weight of nickel, cobalt, and manganese in the nickel-cobalt-manganese solution was 1:19.

[0214] After completion of the co-precipitation reaction, the reaction material was transferred to an aging vessel, and a specific amount of washing additives was added. After stirring for one hour, the material was dewatered, washed, dewatered again, dried, sieved, and demagnetized to obtain a precursor of the positive electrode active material with carbon spheres at its center.

[0215] The precursor of the positive electrode active material and lithium carbonate were uniformly mixed in a specific ratio, where the molar ratio of Li / Me was 1.02; and Me denoted the total molar content of the elements nickel, cobalt and manganese.

[0216] The uniformly mixed material was placed in an oxygen atmosphere furnace. The heating rate was set to 5 °C / min, and the temperature was maintained at 705 °C for 6 hours. The atmospheric conditions required an oxygen content ≥ 98%. The material was then cooled in the furnace.

[0217] The material obtained after calcination was crushed by roller crushing and ultracentrifugal milling and then sieved through a 400-mesh sieve to obtain the positive electrode active material. 2) Production of a positive electrode sheet

[0218] The aforementioned positive electrode active material, the conductive agent carbon black, and the binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 97:1:2, then N-methyl-2-pyrrolidone was added, and the mixture was mixed and stirred for 3 hours to obtain the positive electrode paste; the aluminum foil of the positive electrode current collector was uniformly coated with the positive electrode paste, and after drying, cold pressing, and cutting, the positive electrode sheet was obtained. 3) Production of a negative electrode sheet

[0219] Artificial graphite doped with silicon monoxide, the conductive agent carbon black, carbon nanotubes (CNTs), the binder styrene-butadiene rubber (SBR), and the thickening agent sodium carboxymethylcellulose (CMC) were added to deionized water in a weight ratio of 94.5:1:0.375:2.8:1.325 and mixed and stirred for 0.5 to 6 hours to produce a negative electrode paste, with the mass fraction of silicon monoxide being 70% based on the mass of artificial graphite and silicon monoxide. The copper foil of the negative electrode current collector was then uniformly coated layer by layer with the negative electrode paste. After drying, cold pressing, and cutting, the negative electrode sheet was obtained. 4) Electrolyte solution

[0220] In an argon atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), the lithium salt LiPF6 / LIFSI was dissolved in an organic solvent mixture of ethylene carbonate / ethyl methyl carbonate / diethyl carbonate / fluoroethylene carbonate (volume ratio of 1:1:1:1) and stirred uniformly to obtain an electrolyte solution with a lithium salt concentration of 1 mol / L. 5) Separator

[0221] A polypropylene film was used as the base film, and 1 micrometer of aluminum oxide and 1 micrometer of polyvinylidene fluoride were applied to the base film. 6) Manufacturing a battery

[0222] The positive electrode sheet, the separator, and the negative electrode sheet were stacked sequentially. The separator was positioned between the positive and negative electrode sheets to provide insulation, and a bare cell was produced by winding. Electrode tabs were welded to the bare cell, which was then inserted into an aluminum casing. After drying at 80 °C to remove water, the electrolyte solution was added, and the casing was sealed to obtain an uncharged battery. The uncharged battery then sequentially underwent the following process steps, including resting, hot-cold pressing, formation, shaping, and capacity testing, to produce the lithium battery product of embodiment 1. Examples 2 to 24

[0223] The manufacturing process of the battery of embodiments 2 to 24 is similar to that of the battery of embodiment 1, however, the composition of the positive electrode active material and the process for its manufacture have been adapted, with the specific parameters shown in Table 1. Comparative example 1

[0224] The manufacturing process of the battery of Comparative Example 1 is similar to that of the battery of Exemplary Example 1, however, no hard template medium of carbon spheres was added during the co-precipitation reaction process, and the manufacturing process is specifically as follows: Comparative examples 2 to 3

[0225] The manufacturing process of the battery of comparative examples 2 to 3 is similar to that of the battery of embodiment 1, however, the parameters of the manufacturing process of the positive electrode active material have been adapted, with the specific parameters shown in Table 1. Comparative example 4

[0226] The manufacturing process for the battery in Comparative Example 4 was similar to that of Exemplary Example 21; however, no hard template material made of carbon spheres was added during the reaction process. The specific parameters are listed in Table 1. Comparative examples 5 to 6

[0227] The manufacturing process of the battery of comparative examples 5 to 6 is similar to that of the battery of embodiment 21, however, the parameters of the manufacturing process of the positive electrode active material have been adapted, with the specific parameters shown in Table 1. II. Performance Tests 1. Performance test of the positive electrode active material 1) Test of the inner diameter of the hollow structure

[0228] A conductive adhesive was applied to a sample stage, and the powdered samples of the positive electrode active material from the respective embodiments and comparative examples were evenly distributed on the conductive adhesive. The non-adherent powder was blown away with a rubber suction bulb, a gold coating was applied, and the particles of the powdered samples were sectioned using argon plasma. Scanning electron microscope images of the powdered sample were obtained using a scanning electron microscope (e.g., ZEISS Sigma 300) at an accelerating voltage of 10 kV and an emission current of 10 mA. The inner diameter of the hollow structure was measured according to the SEM images. At least three samples, each with at least 50 data points, were measured. The arithmetic mean was used as the inner diameter of the hollow structure of the sample. 2) Porosity test

[0229] The porosity of the positive electrode active material could be tested using any method known in the art. As an example, the measurement was performed using the gas displacement method according to GB / T24586. The porosity = (V1 - V2) / V1 * 100%, where V1 was the apparent volume of the sample and V2 was the actual volume of the sample. 3) Outer wall thickness of the hollow structure

[0230] A conductive adhesive was applied to a sample stage, and the powdered samples of the positive electrode active material from the respective embodiments and comparative examples were evenly distributed on the conductive adhesive. The non-adherent powder was blown away with a rubber suction bulb, a gold coating was applied, and the particles of the powdered samples were sectioned using argon plasma. Scanning electron microscope images of the powdered sample were obtained using a scanning electron microscope (e.g., ZEISS Sigma 300) at an accelerating voltage of 10 kV and an emission current of 10 mA. The outer wall thickness of the hollow structure was measured according to the SEM images. At least three samples, each with at least 50 data points, were measured. The arithmetic mean was used as the outer wall thickness of the hollow structure in the sample. 4) Specific surface area test

[0231] Reference was made to GBIT 19587-2017 "Determination of the specific surface area of ​​solids by gas adsorption using the BET method". The determination was carried out using the TriStar II 3020 instrument. The positive electrode active material was dispersed in a dispersing agent (ethanol), treated with ultrasound for 30 minutes, the resulting material was dried in a vacuum drying oven, and finally the specific surface area of ​​the positive electrode active material was measured using a specific surface area measuring device. 4) Dv50 Test

[0232] According to GB / T 19077-2016 "Particle size distribution - Laser diffraction method", 0.1 g to 0.13 g of the positive electrode active material sample to be tested was weighed into a 50 mL beaker, 5 g of anhydrous ethanol was added, a stirring rod of approximately 2.5 mm was added, and the beaker was sealed with cling film. After a 5-minute ultrasonic treatment, the sample was placed on a magnetic stirrer and stirred at 500 rpm for at least 20 minutes. Two samples were taken from each product batch for testing. The test was performed using a Mastersizer 2000E laser particle size analyzer from Malvern Instruments Ltd., UK. Here, Dv50 is the particle size at which the cumulative volume distribution percentage of secondary particles of the positive electrode active material reaches 50%. 5) SPAN Test

[0233] According to GB / T 19077-2016 "Particle size distribution - Laser diffraction method", 0.1 g to 0.13 g of the positive electrode active material sample to be tested was weighed into a 50 mL beaker, 5 g of anhydrous ethanol was added, a stirring rod of approximately 2.5 mm was added, and the container was sealed with cling film. After a 5-minute ultrasonic treatment, the sample was placed on a magnetic stirrer and stirred at 500 rpm for at least 20 minutes. Two samples were taken from each product batch for testing. The test was performed using a Mastersizer 2000E laser particle size analyzer from Malvern Instruments Ltd., UK.SPAN = (Dv90 - Dv10) / Dv50, where Dv90 of the secondary particles was the particle size at which the cumulative volume distribution percentage of the secondary particles of the positive electrode active material reached 90%, Dv50 of the secondary particles was the particle size at which the cumulative volume distribution percentage of the secondary particles of the positive electrode active material reached 50%, and Dv10 of the secondary particles was the particle size at which the cumulative volume distribution percentage of the secondary particles of the positive electrode active material reached 10%. 6) Area of ​​the (010) crystal plane

[0234] The area of ​​the (010) crystal plane was measured using an X-ray powder diffractometer (XRD, instrument type: Bruker D8 ADVANCE) using Cu Kα as the target material; the voltage was 40 kV and the current was 40 mA, the scan angle range was between 5° and 80°, the step size was 0.00836° and the time per step was 0.3 seconds. 7) Test method for primary particle size

[0235] After 500x imaging using a scanning electron microscope (ZEISS Sigma-02-33, Germany), 200 to 600 fully formed and unobscured primary particles of the positive electrode active material were randomly selected from the electron microscopic image, and the mean of the largest diameter of the primary particles in the microscopic image was recorded as the average particle size. 2. Battery performance test 1) Discharge capacity test

[0236] The battery cell was left to rest at 25 °C for 2 hours to ensure its temperature was 25 °C. At 25 °C, the battery cell was charged at 0.1 C to the final charging voltage of 4.3 V and continued charging at constant voltage until the current reached 0.02 C, at which point charging was terminated (where C represented the nominal capacity of the battery cell). The battery cell was then left to rest at 25 °C for 0.5 hours. Finally, the battery cell was discharged at 0.1 C at 25 °C to the final discharge voltage of 2.5 V, and the total discharge capacity C0 was recorded. 2. Energy density test

[0237] Battery cell capacity test: The battery cell was left to rest at 25 °C for 2 hours to ensure the temperature remained at 25 °C. At 25 °C, the battery cell was charged at 0.1 C to the final charging voltage and continued charging at constant voltage until the current reached 0.05 C, at which point charging was terminated (where C represented the nominal capacity of the battery cell). The battery cell was then left to rest at 25 °C for 1 hour. Finally, the battery cell was discharged at 0.1 C at 25 °C to the final discharge voltage, and the total discharge capacity C0 was recorded. The total discharge energy was denoted E0.

[0238] Weight measurement of the battery cell: The battery cell was placed on an electronic scale until the weight was stable, and the weight value M0 of the battery cell was read.

[0239] Calculation of energy density: The discharge energy E0 of the battery cell divided by the weight M0 of the battery cell yielded the energy density of the battery cell. 3) Testing the charging time from 10% to 80% SOC

[0240] Voltage calibration: A stacked battery with three electrodes of the same battery design was left to rest for 30 minutes at 25 °C; the battery cell was charged at 25 °C at 0.33 C to the final charge voltage and continued charging at the final charge voltage at constant voltage until the current reached 0.05 C and the charge was terminated (where C represented the nominal capacity of the battery cell); the battery cell was left to rest for 1 hour at 25 °C; the battery cell was discharged at 0.33 C at 25 °C to the discharge cut-off voltage and the total discharge capacity C1 from the battery cell was recorded; the battery cell was left to rest for 1 hour at 25 °C.

[0241] Charging test: The stacked three-electrode cell was left to rest at 25 °C for 30 minutes; discharged to the discharge cut-off voltage with 0.33 C1 DC; left to rest for 5 minutes; charged to the charging cut-off voltage with x C1 CC (the anode potential was monitored using three electrodes; as soon as the anode potential reached 0 V, the next step was initiated; this process was repeated 9 times, with x successively assuming the values ​​5, 4, 4.5, 3, 2, 1, 0.8, 0.5 and 0.33; the x-value and the charging capacity Cx corresponding to the anode potential of 0 V were determined). 4) Testing the battery's cyclic capacity retention rate

[0242] The secondary batteries produced in the individual embodiments and comparative examples were charged at a constant rate of 0.5 C to a final charging voltage of 4.25 V, then charged at a constant voltage to a current ≤ 0.05 C, left to rest for 5 minutes, and finally discharged at a constant rate of 0.33 C to a final discharge voltage of 2 V and left to rest for 5 minutes. This corresponded to one charge-discharge cycle. Following this procedure, the battery was subjected to a cyclic charge-discharge test until the battery capacity decreased to 80%. The number of cycles at this point corresponded to the battery's cycle life at 25 °C. III. Analysis of the test results of the respective implementation examples and comparison examples

[0243] Batteries according to the individual embodiments and comparative examples were manufactured using the above-mentioned method, and their performance parameters were measured. The results are listed in Tables 1, 2, and 3 below. Table 1 Serial number Co-felling Calcination Diameter of the hard template medium (in µm) Ratio of the weight of the hard template medium to the total weight of the elements nickel, cobalt and M pH Temperature (in °C) Time (in hours) Stirring speed (in rpm) Temperature (in °C) Time (in hours) Example 1 0,25 1:19 10,8 60 6 800 705 6 Example 2 1,75 5:15 11,2 65 12 750 720 7 Example 3 2,2 6:14 11,4 70 14 700 730 8 Example 4 2,35 8:12 11,8 75 18 650 750 10 Example 5 0,6 8:12 10,8 60 6 800 705 6 Example 6 0,9 3:17 11 63 10 760 715 7,5 Example 7 2,35 8:12 11,8 75 18 650 750 10 Example 8 2,5 4:16 12,4 78 19 670 735 11 Example 9 2,35 8:12 11,2 68 12 610 720 10 Example 10 2,35 8:12 11,4 70 14 620 730 10 Example 11 2,35 8:12 11,6 73 15 630 740 10 Example 12 2,35 8:12 11,2 75 18 650 750 10 Example 13 2,35 8:12 11,3 76 18 680 753 10 Example 14 2,35 8:12 11,2 78 18 670 755 10 Example 15 2,35 8:12 11,5 79 18 660 758 10 Example 16 2,35 8:12 11,6 81 18 690 761 10 Example 17 2,35 8:12 11,8 82 18 750 763 10 Example 18 2,35 8:12 11,9 80 18 720 765 10 Example 19 2,35 8:12 11,7 83 18 710 768 10 Example 20 2,35 8:12 12 82 18 705 769 10 Example 21 2,35 8:12 11,8 75 18 650 750 10 Example 22 2,35 8:12 12,8 75 16 680 750 10 Example 23 2,35 8:12 12,2 75 15 690 750 10 Example 24 2,35 8:12 11,8 75 18 650 750 10 Comparative example 1 / / 10,8 60 6 800 705 6 Comparative example 2 0,15 0,5:19,5 10,9 62 6 850 705 6 Comparative example 3 7 8:12 11,8 75 18 650 750 10 Comparative example 4 / / 11,8 75 18 650 750 10 Comparative example 5 0,1 1:19 12,2 70 16 680 750 10 Comparative example 6 7 2:18 11,8 74 18 640 750 10 Table 2 Serial number Positive electrode active material Chemical formula Inner diameter d1 (µm) Dv50 / (d1+ d2) Outer wall thickness d2 (µm) Dv50 value (µm) porosity Specific surface area (m²) 2 / G) SPAN Area of ​​the (010) crystal plane ne (µm²) 2 ) Primary particle size (µm) Example 1 LiNi 0,97 Co 0,02 Mr 0,01 O2 0,3 1,08 8 9 1% 0,4 1,23 20 0,8 Example 2 LiNi 0,97 Co 0,02 Mr 0,01 O2 2 1,13 6 9 6% 0,9 1,23 180 0,5 Example 3 LiNi 0,97 Co 0,02 Mr 0,01 O2 2,5 1,13 5,5 9 8% 1,1 1,23 200 0,4 Example 4 LiNi 0,97 Co 0,02 Mr 0,01 O2 3 1,29 4 9 10 % 1,4 1,23 240 0,2 Example 5 LiNi 0,97 Co 0,02 Mr 0,01 O2 0,5 1,06 8 9 0,50 % 0,5 1,23 30 0,25 Example 6 LiNi 0,97 Co 0,02 Mr 0,01 O2 1,6 1,07 6,8 9 3 % 1,26 1,23 234 0,35 Example 7 LiNi 0,97 Co 0,02 Mr 0,01 O2 3 1,29 4 9 9% 1,4 1,23 240 0,2 Example 8 LiNi 0,97 Co 0,02 Mr 0,01 O2 5 1,13 3 9 15 % 1,8 1,23 252 0,24 Example 9 LiNi 0,97 Co 0,02 Mr 0,001 O2 3 0,43 4 3 10 % 0,7 0,78 210 0,2 Example 10 LiNi 0,97 Co 0,02 Mr 0,001 O2 3 0,71 4 5 10 % 0,9 0,9 220 0,2 Example 11 LiNi 0,97 Co 0,02 Mr 0,001 O2 3 1,43 4 10 10 % 1,25 1,12 230 0,2 Example 12 LiNi 0,97 Co 0,02 Mr 0,001 O2 3 2,14 4 15 10 % 1,4 1,23 240 0,2 Example 13 LiNi 0,97 Co 0,02 Mr 0,001 O2 3 1,29 4 9 10 % 1,4 0,4 220 0,2 Example 14 LiNi 0,97 Co 0,02 Mr 0,001 O2 3 1,29 4 9 10 % 1,4 0,7 227 0,2 Example 15 LiNi 0,97 Co 0,02 Mr 0,01 O2 3 1,29 4 9 10 % 1,4 1,4 235 0,2 Example 16 LiNi 0,97 Co 0,02 Mr 0,01 O2 3 1,29 4 9 10 % 1,4 2 240 0,2 Example 17 LiNi 0,97 Co 0,02 Mr 0,01 O2 3 1,29 4 9 10 % 1,4 1,2 242 0,1 Example 18 LiNi 0,97 Co 0,02 Mr 0,01 O2 3 1,29 4 9 10 % 1,4 1,2 242 0,15 Example 19 LiNi 0,97 Co 0,02 Mr 0,01 O2 3 1,29 4 9 10 % 1,4 1,2 242 0,5 Example 20 LiNi 0,97 Co 0,02 Mr 0,001 O2 3 1,29 4 9 10 % 1,4 1,2 242 0,9 Example 21 LiNi 0,97 Co 0,03 O2 3 1,29 4 9 10 % 1,4 1,25 240 0,22 Example 22 LiNi 0.995 Co 0.00 4Mn 0,001 O2 3 1,29 4 9 10 % 1,6 1,25 241 0,18 Example 23 LiNi 0,95 Co 0,04 Mr 0,001 O2 3 1,29 4 9 10 % 1,4 1,25 241 0,2 Example 24 LiNi 0,97 Co 0,02 Sb 0,01 O2 3 1,29 4 9 10 % 1,4 1,2 242 0,2 Comparative example 1 LiNi 0,97 Co 0,02 Mr 0,01 O2 / / / 9 / 1,4 1,23 220 0,2 Comparative example 2 LiNi 0,97 Co 0,02 Mr 0,01 O2 0,1 1,11 8 9 0,30 % 0,45 1,23 18 0,8 Comparative example 3 LiNi 0,97 Co 0,02 Mr 0,001 O2 6 0,9 4 9 10 % 1,4 1,23 240 0,2 Comparative example 4 LiNi 0,97 Co 0,03 O2 / / / 9 / 0,4 1,23 240 0,2 Comparative example 5 LiNi 0,97 Co 0,03 O2 0,1 2,20 4 9 0,50 % 1,4 1,23 32 0,2 Comparative example 6 LiNi 0,97 Co 0,03 O2 6 0,9 4 9 0,7% 1,4 1,23 60 0,2 Table 3 Serial number Battery power Discharge capacity (mAh) Energy density (Wh / kg) Charging time (minutes) Cycle count Example 1 241 413 18 800 Example 2 247 421 15 1000 Example 3 249 423 10 1500 Example 4 251 428 9 1200 Example 5 243 420 16 950 Example 6 250 426 10 1480 Example 7 251 428 9 1500 Example 8 252 429 9 1000 Example 9 248 425 12 1350 Example 10 249 426 11 1400 Example 11 250 427 10 1550 Example 12 251 428 9 1500 Example 13 246 427 10 1250 Example 14 247 427 10 1350 Example 15 250 427 10 1500 Example 16 250 427 10 1250 Example 17 251 421 9 1050 Example 18 251 421 10 1500 Example 19 250 420 11 1480 Example 20 249 419 12 1150 Example 21 250 420 10 1000 Example 22 252 425 16 1100 Example 23 243 416 15 1250 Example 24 247 418 14 1100 Comparative example 1 232 400 25 500 Comparative example 2 236 405 22 550 Comparative example 3 251 426 9,5 700 Comparative example 4 230 396 28 395 Comparative example 5 228 397 26 300 Comparative example 6 229 399 24 380

[0244] According to the results mentioned above, the positive electrode active material in embodiments 1 to 24 has an arbitrary chemical formula of LiNi. 0,97 Co 0,02 Mn 0,01 C2, LiNi 0,97 Co 0,03 O2, LiNi 0,995 Co 0,004 Mn 0,001 O2, LiNi 0,95 Co 0,04 Mn 0,01 O2 or LiNi 0,97 Co 0,02 Sb 0,01 O2 on.

[0245] The morphology of the positive electrode active material in embodiment 4 is tested using a scanning electron microscope (SEM). The test result is shown in Fig. Figure 1 shows that the positive electrode active material has a hollow structure. The positive electrode active material in embodiments 1 to 24 each has a hollow structure, wherein the inner diameter d1 of the hollow structure is 0.3 µm to 5 µm.

[0246] From the comparison of embodiments 1 to 20 with comparative example 1 and embodiment 21 with comparative example 4, it can be seen that the positive electrode active material with hollow structure can increase the discharge capacity and energy density of the battery, shorten the charging time of the battery, improve the rate performance of the battery and increase the cycle performance of the battery.

[0247] A comparison of embodiments 1 to 20 with those 2 to 3, and of embodiment 21 with those 5 to 6, shows that an inner diameter d1 of the hollow structure of 0.3 µm to 5 µm can improve the battery's cycle performance. At the same time, the battery exhibits a high discharge capacity and energy density, as well as excellent rate performance, which comprehensively improves the battery's electrochemical performance.

[0248] A comparison of embodiments 2 to 4 and 6 to 20 with embodiments 1 and 5 shows that an inner diameter d1 of the hollow structure of 1.5 µm to 5 µm can further increase the cycle performance and rate performance of the battery.

[0249] From the comparison of embodiments 4, 7, 11 to 16 with embodiments 9 to 10, it can be seen that the energy density and the rate performance of the battery can be improved by controlling the Dv50 value of the positive electrode active material, the inner diameter d1 and the outer wall thickness d2 of the hollow structure such that 1 ≤ Dv50 / (d1 + d2) ≤ 4.

[0250] From embodiments 1 to 24, it is evident that with an outer wall thickness d2 of the hollow structure of 3 µm to 10 µm, the battery exhibits a high discharge capacity and energy density as well as excellent rate and cycle performance, which comprehensively improves the electrochemical performance of the battery. A comparison of embodiments 2 to 4 and 6 to 20 with embodiments 1 and 5 shows that an outer wall thickness d2 of the hollow structure of 3 µm to 7 µm can further increase the cycle and rate performance of the battery.

[0251] A comparison of embodiments 4, 7, and 10 to 16 with embodiment 9 shows that a Dv50 value of the positive electrode active material of 5 µm to 15 µm can increase the energy density and rate performance of the battery. A comparison of embodiments 4, 7, and 11 to 16 with embodiments 9 to 10 shows that a Dv50 value of the positive electrode active material of 8 µm to 10 µm can further improve the energy density and rate performance of the battery.

[0252] As shown in embodiments 1 to 24, a positive electrode active material porosity of 0 to 20% results in a battery with high discharge capacity and energy density, as well as excellent rate and cycle performance, thereby comprehensively improving the battery's electrochemical performance. A comparison of embodiments 2 to 4, 6 to 8, and 13 to 16 with embodiments 1 and 5 shows that a positive electrode active material porosity of 2% to 15% can increase the battery's discharge capacity and energy density, as well as improve its rate and cycle performance.

[0253] Exemplary embodiments 1 to 24 show that with a specific surface area of ​​the positive electrode active material of 0.4 m² 2 / g up to 1.4 m 2 / g the battery has a high discharge capacity and energy density as well as excellent rate and cycle performance, thereby comprehensively improving the electrochemical performance of the battery.

[0254] A comparison of embodiments 4 and 15 to 16 with embodiments 13 to 14 shows that a SPAN value of the positive electrode active material of 1 to 1.5 can increase the discharge capacity of the battery. A comparison of embodiments 4 and 15 with embodiments 13 to 14 and 16 shows that a SPAN value of the positive electrode active material of 1.2 to 1.4 can ensure both the cycle life and the rate performance of the battery and can comprehensively improve the electrochemical performance of the battery.

[0255] From embodiments 1 to 24 it can be seen that with an area of ​​the (010) crystal plane of the positive electrode active material of greater than or equal to 6 µm 2The battery has a high discharge capacity and energy density, as well as excellent rate and cycle performance, which comprehensively improves the electrochemical performance of the battery.

[0256] A comparison of embodiments 17 to 19 with embodiment 20 shows that with a primary particle size of the positive electrode active material of 0.1 µm to 0.8 µm, the discharge capacity and energy density of the battery can be increased and the rate performance of the battery improved. A comparison of embodiments 18 to 19 with embodiments 17 and 20 shows that a primary particle size of the positive electrode active material of 0.15 µm to 0.3 µm can improve the cycle performance of the battery. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited non-patent literature

[0000] GB / T 19587-2017

[0097] GB / T 19077-2016

[0232]

Claims

[1] Positive electrode active material, characterized by that the chemical formula of the positive electrode active material Li a Ni x Co y M 1-x-y O2 is defined as follows, where M comprises one or more of Mn, Al, B, Zr, Sr, Y, Sb, W, Ti, Mg and Nb, where 0.55 ≤ x ≤ 1.0, 0 ≤ y ≤ 0.45, 0.8 ≤ a ≤ 1.2, and where the positive electrode active material has a hollow structure, wherein the inner diameter d1 of the hollow structure is 0.3 µm to 5 µm. [2] Positive electrode active material according to claim 1, characterized by , that in the chemical formula Li a Ni x Co y M 1-x-y O2 applies: 0.6 ≤ x ≤ 1.0, optional 0.8 ≤ x ≤ 1.0, or 0.9 ≤ x ≤ 1.0, 0 ≤ y ≤ 0.1, 0.8 ≤ a ≤ 1.2, optional 0.95 ≤ x ≤ 0.995, 0 ≤ y ≤ 0.05, 0.8 ≤ a ≤ 1.

2. [3] Positive electrode active material according to claim 1 or 2, characterized by , that the inner diameter d1 of the hollow structure is 1.5 µm to 5 µm. [4] Positive electrode active material according to any one of claims 1 to 3, characterized by , that the positive electrode active material satisfies the following relationship: 1 ≤ Dv50 / (d1 + d2) ≤ 4, where d1 in µm denotes the inner diameter of the hollow structure, d2 in µm denotes the outer wall thickness of the hollow structure, and Dv50 in µm denotes the Dv50 value of the positive electrode active material. [5] Positive electrode active material according to any one of claims 1 to 4, characterized by , that the outer wall thickness d2 of the hollow structure is 3 µm to 10 µm, optionally 3 µm to 7 µm. [6] Positive electrode active material according to any one of claims 1 to 5, characterized by , that the Dv50 value of the positive electrode active material is 5 µm to 15 µm, optionally 5 µm to 10 µm, or 8 µm to 10 µm. [7] Positive electrode active material according to any one of claims 1 to 6, characterized bythat the porosity of the positive electrode active material is 0 to 20%, optionally 2% to 15%. [8] Positive electrode active material according to any one of claims 1 to 7, characterized by , that the specific surface area of ​​the positive electrode active material is 0.4 m² 2 / g up to 1.4 m 2 / g. [9] Positive electrode active material according to any one of claims 1 to 8, characterized by , that the SPAN value of the positive electrode active material is 1 to 1.5, optionally 1.2 to 1.

4. [10] Positive electrode active material according to any one of claims 1 to 9, characterized by , that the area of ​​the (010) crystal plane of the positive electrode active material is greater than or equal to 6 µm 2 is. [11] Positive electrode active material according to any one of claims 1 to 10, characterized by , that the primary particle size of the positive electrode active material is 0.1 µm to 0.8 µm, optionally 0.15 µm to 0.3 µm. [12] Positive electrode sheet, characterized by , that the positive electrode sheet comprises the positive electrode active material according to any one of claims 1 to 10. [13] Secondary battery, characterized by , that it comprises a positive electrode sheet according to claim 12. [14] Power-consuming device, characterized by that it comprises a secondary battery according to claim 13.

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