High-nickel positive electrode material, secondary battery and electric device

Abstract

A high-nickel positive electrode material, a secondary battery and an electric device. The positive electrode material satisfies: 20≤A*B≤50, wherein A is a mixed occupancy ratio of lithium atoms and nickel atoms in the positive electrode material, and B is the average number of primary particles per square micron cross-section of secondary particles with a particle diameter of 5-15 μm in the positive electrode material. In a product to which the positive electrode material is applied, primary particles in secondary particles are protected from the risk of squeezing breakage caused by an excessively dense arrangement thereof, and a sufficient transmission space for lithium ion deintercalation can also be provided; in addition, the problem of lithium deposition caused by mixed arrangement of lithium and nickel is avoided during charging and discharging. Thus, the product has ideal charging and discharging activity and cycling stability.

Description

High-nickel positive electrode material, secondary battery and power-consuming device Technical Field

[0001] The present invention relates to the field of energy storage, and in particular to a high-nickel positive electrode material, a secondary battery and an electrical device. Background Art

[0002] Among the new generation of energy storage devices, lithium-ion batteries are gradually becoming the market leader due to their high energy density, high economic benefits, and high environmental protection. As the core component of lithium-ion batteries, the positive electrode has a significant impact on the charge and discharge capacity and service life of the entire device. This is especially true for the mainstream positive electrode ternary electrode. Research has found that various physical and chemical parameters, including the compaction density of the electrode itself and the type and ratio of the ternary elements in the active ingredients, can significantly affect the electrochemical performance of the final electrode when used in lithium-ion batteries.

[0003] Since most ternary materials are prepared by calcination, the crystal phase of the product changes during the calcination process. Especially in the preparation of nickel-containing materials, as the calcination temperature is adjusted, the mixed ratio of lithium atoms and nickel atoms in the product (mainly obtained by performing XRD detection on the product and then modifying and fitting the spectrum) will also change accordingly. Existing research theory believes that the smaller the mixed ratio of lithium atoms and nickel atoms, the better the electrochemical performance of the ternary material. Therefore, when exploring the preparation conditions for a specific ternary material, the calcination temperature corresponding to the lower Li / Ni mixed ratio of the product is mainly used as the preferred condition.

[0004] However, in actual applications, the ternary material products prepared under optimal conditions did not show the expected electrochemical properties, and even had huge deviations. If this problem is not solved, the initial R&D costs of the products will remain high, and the electrochemical performance of the products still needs to be improved.

[0005] Summary of the Invention

[0006] Based on the defects of the existing technology, the purpose of the present invention is to provide a high-nickel positive electrode material. By limiting the parameters A and B of the product to a specific range, the product can achieve a higher charge and discharge capacity and ideal cycle stability.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A positive electrode material comprising lithium and nickel, the positive electrode material comprising primary particles and secondary particles formed by stacking the primary particles, the positive electrode material satisfying: 20≤A*B≤50;

[0009] Wherein A is the mixed occupancy ratio of lithium atoms and nickel atoms in the positive electrode material, and B is the average number of primary particles per square micrometer cross section in secondary particles with a particle diameter of 5 to 15 μm in the positive electrode material.

[0010] The mixed occupancy ratio of lithium atoms and nickel atoms in the positive electrode material of the present invention refers to the molar ratio of lithium atoms and nickel atoms in the layered structure of the positive electrode material. The specific definition that can be obtained is: the mixed occupancy ratio of lithium and nickel (Li / Ni) obtained by calculating the XRD diffraction peak of the positive electrode material powder in the XRD pattern of the positive electrode material by commonly used structure refinement software (TOPAS, Fullproof, GSAS), and the specific steps include software import of original spectrum data, correction of scale, unit cell parameters and instrument zero point, adjustment of scale factor (W, U, V, etc.), Occ correction, and refinement and fitting of corresponding atomic coordinate data. The fitted data is only data within the range of 10 to 90° of the XRD pattern.

[0011] The inventors found that in nickel-containing positive electrode materials, the well-known Li / Ni mixed ratio (commonly known as lithium-nickel mixed ratio) is not the only parameter that affects the electrochemical performance of the product. Since the doping elements in the positive electrode material are not actually distributed in a gradient concentration, during the calcination process, when the calcination conditions change, the Li / Ni mixed ratio changes, and the material particle morphology also changes. In particular, the gradual increase in the calcination temperature will lead to an increase in the size of the primary particles in the material (at this time, the size of the secondary particles may not change significantly, while the large-sized primary particles will change during the charge and discharge cycle). The large extrusion stress will cause small cracks in the active material on the surface of the electrode, which will eventually lead to a significant reduction in the cycle stability of the product; however, if the calcination temperature is too low and the size of the primary particles is too small, the contact interface between the particles will be too large, which will inhibit the conduction of lithium ions during the charge and discharge process and thus show unsatisfactory electrochemical performance. Similarly, the length of calcination time will also cause a certain change in the size of the primary particles. At the same time, the particle distribution of the positive electrode material is usually basically 2 to 30μm, but in the process of lithium ion deintercalation, the main function of small-sized particles is to enhance the overall vibration. The actual density and the reduction of the diffusion path of lithium ions, while the embedding stability of lithium ions (that is, the decisive factor affecting the energy density and charge-discharge stability of the final material) mainly comes from larger particles with a larger size, that is, particles in the range of 5 to 15 μm. Therefore, in the technical solution of the present invention, the positive electrode material uses the product of the number of primary particles per unit area in the secondary particles with a particle size range of 5 to 15 μm (that is, the size of the primary particles in the secondary particles) and the Li / Ni mixing ratio of the material as a limiting parameter. When the product of the two parameters is in the range of 20 to 50, the Li / Ni mixing ratio in the product can be in a suitable range (the Li / Ni mixing ratio and the preparation conditions of the product do not have an obvious correlation trend after analysis). At the same time, during the charge and discharge process, the charge and discharge capacity of the product will not be low or the cycle stability will be poor due to the problem of the primary particle size in the secondary particles. The product can achieve ideal electrochemical performance. After inspection, the calcination conditions corresponding to the products within the range are not the same as the optimal calcination conditions determined based on the known Li / Ni mixing ratio and the research theory of the change in the size of the primary particles of the positive electrode material.

[0012] For ease of description and explanation, the present invention will hereinafter refer to A*B as PPD (primary particle distribution). Those skilled in the art should be aware that the definition of PPD does not lead to different interpretations or explanations of parameter A, parameter B, or their product.

[0013] It should be noted that the method for obtaining the mixed occupancy ratio of lithium atoms and nickel atoms in the positive electrode material of the present invention can be: performing XRD detection on the positive electrode material powder to obtain an XRD spectrum, and then using conventional software such as TOPAS (Coelho Software), GSAS, Fullproof, etc. to fit the XRD spectrum analysis software of the positive electrode powder to obtain a relevant value (refinement accuracy parameter R wp and R p less than 10%).

[0014] The method for determining the average number of primary particles per square micrometer of cross section in the secondary particles with a particle diameter of 5 to 15 μm in the positive electrode material of the present invention can be:

[0015] A positive electrode material sample of secondary particles with a diameter of 5 to 15 μm is taken and then cut, such as using a focused ion beam (FIB) or an ion beam cross section polisher (CP). The cut sample cross section is examined by scanning electron microscopy (SEM) to obtain a cross-sectional SEM image of the sample.

[0016] In the cross-sectional SEM images of the samples, use pattern recognition software such as Dragonfly (Object Research Systems) or Avizo (Thermo Fisher Scientific) to count the number of primary particles and the area of ​​each primary particle. Alternatively, manually calculate the area and number of particles to obtain the number of primary particles per square micron = the number of all primary particles / the sum of the areas of all primary particles.

[0017] The sum of the areas of all primary particles can be directly determined using software, or the cross-sectional area of ​​the sample and the interstitial areas between the primary particles in the sample cross-section can be pre-determined, and then the sum can be calculated by taking the difference between the cross-sectional area of ​​the sample and the interstitial areas between the primary particles in the sample cross-section. However, when calculating the sum using the difference, it is important to ensure that the interstitial area accounts for less than 1% of the sample cross-sectional area, otherwise the error will be large and the final calculation accuracy will be reduced.

[0018] In the present invention, the number of samples of the secondary particles is at least greater than 30, and the calculated data is the statistical average value of the batch of samples.

[0019] Preferably, the mixed site ratio of lithium atoms and nickel atoms in the positive electrode material is 1.2-5.

[0020] More preferably, the mixed site ratio of lithium atoms and nickel atoms in the positive electrode material is 1.5 to 4.2.

[0021] More preferably, the mixed occupancy ratio of lithium atoms and nickel atoms in the positive electrode material is any one of 1.5, 1.6, 1.7, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2 or a range between two of them.

[0022] It is generally known that as the calcination temperature increases, the overall change trend of the Li / Ni mixed ratio in the product is first increased and then decreased. However, based on the different doping elements in the positive electrode material, especially the nickel element, as the calcination temperature of the product changes during the preparation process, the mixed occupancy ratio of lithium atoms and nickel atoms also varies. The inventors have preferred that the positive electrode material performance is better when the mixed occupancy ratio of lithium atoms and nickel atoms is 1.5 to 4.2.

[0023] Preferably, in the positive electrode material, the average number of primary particles per square micrometer of cross section in the secondary particles with a particle diameter of 5 to 15 μm is 4 to 25.

[0024] More preferably, the average number of primary particles per square micrometer of cross section in the secondary particles with a particle diameter of 5 to 15 μm in the positive electrode material is 6 to 19.

[0025] More preferably, the average number of primary particles per square micrometer of cross section in the secondary particles with a particle diameter of 5 to 15 μm in the positive electrode material is any one of 6, 7, 8, 9, 10, 11, 12, 14, 16, 17, 18, 19 or a range between two of them.

[0026] Generally speaking, the fewer the number of primary particles at the interface per unit area of ​​the secondary particles, the larger the size of the primary particles in the secondary particles. Under normal circumstances, during the charge and discharge process, the expansion and contraction volume of the primary particles is basically 2-4%. After optimization by the inventors, when the average number of primary particles per square micrometer cross-section in the secondary particles with a particle diameter of 5-15 μm in the positive electrode material is within the above range, the size of most of the primary particles in the positive electrode material will not be too small, and they will basically not be squeezed against each other and broken during the charge and discharge process, and the electrochemical performance will be better.

[0027] Preferably, A*B satisfies: 25≤A*B≤40.

[0028] The inventors have verified that when the primary particle distribution characteristic parameter PPD of the positive electrode material meets the above preferred range, the product can have both better discharge specific capacity and cycle stability.

[0029] Preferably, the positive electrode material comprises LiNi x M 1-x O2 or LiNi y Coz M' 1-y-z O2;

[0030] The M is any one of Co, Mn, and Mg, and 0.7≤x≤0.98;

[0031] The M' is any one of Mn, Mg, and Al, 0.7≤y≤0.98, 0.05≤z≤0.3, and y+z<1.

[0032] More preferably, the positive electrode material further includes a doping element, and the doping element is at least one of niobium, tungsten, molybdenum, tantalum, titanium, zirconium, boron, aluminum, and magnesium.

[0033] Preferably, the positive electrode material is LiNi 0.9 M 0.1 O2; the mixed occupancy ratio of lithium atoms and nickel atoms in the positive electrode material is 2.2 to 3.7, and the average number of primary particles per square micron cross section in the secondary particles with a particle diameter of 5 to 15 μm in the positive electrode material is 5 to 18.

[0034] Preferably, the positive electrode material is LiNi 0.95 M 0.05 O2; the mixed occupancy ratio of lithium atoms and nickel atoms in the positive electrode material is 3 to 4.5, and the average number of primary particles per square micron cross section in the secondary particles with a particle diameter of 5 to 15 μm in the positive electrode material is 4 to 14.

[0035] Preferably, the positive electrode material is LiNi 0.98 M 0.02 O2; the mixed occupancy ratio of lithium atoms and nickel atoms in the positive electrode material is 2 to 3.6, and the average number of primary particles per square micron cross section in the secondary particles with a particle diameter of 5 to 15 μm in the positive electrode material is 9 to 17.

[0036] Preferably, the positive electrode material is LiNi 0.8 Co 0.1 M' 0.1 O2; the mixed occupancy ratio of lithium atoms and nickel atoms in the positive electrode material is 1.5 to 2.2, and the average number of primary particles per square micron cross section in the secondary particles with a particle diameter of 5 to 15 μm in the positive electrode material is 14 to 24.

[0037] Preferably, the positive electrode material is LiNi 0.9 Co 0.05 M' 0.05 O2; the mixed occupancy ratio of lithium atoms and nickel atoms in the positive electrode material is 1.5 to 2.3, and the average number of primary particles per square micron cross section in the secondary particles with a particle diameter of 5 to 15 μm in the positive electrode material is 12 to 22.

[0038] Preferably, the positive electrode material is LiNi 0.95 Co 0.025 M' 0.025 O2; the mixed occupancy ratio of lithium atoms and nickel atoms in the positive electrode material is 2 to 2.6, and the average number of primary particles per square micron cross section in the secondary particles with a particle diameter of 5 to 15 μm in the positive electrode material is 12 to 22.

[0039] Preferably, the positive electrode material comprises LiNi x M 1-x O2 and niobium, 0.9≤x≤0.98, the mixed occupancy ratio of lithium atoms and nickel atoms in the positive electrode material is 3-4.5, and the average number of primary particles per square micrometer cross section in the secondary particles with a particle diameter of 5-15 μm in the positive electrode material is 6-15.

[0040] Preferably, the positive electrode material comprises LiNi y Co z M' 1-y-z O2 and niobium, 0.8≤y≤0.95, the mixed occupancy ratio of lithium atoms and nickel atoms in the positive electrode material is 1.2-3.5, and the average number of primary particles per square micrometer cross section in the secondary particles with a particle diameter of 5-15 μm in the positive electrode material is 11-22.

[0041] The chemical composition of the positive electrode material of the present invention can be similar to that of existing general positive electrode materials, and additional doping elements can be introduced according to actual needs to improve the overall structural stability and expand the lithium ion deintercalation channel. However, compared with these existing non-doped and doped materials, the positive electrode material of the present invention will not have the electrochemical performance degradation caused by the extrusion and crushing of primary particles in the secondary particles, or the low lithium ion transmission rate due to excessive interface contact between particles during the charge and discharge process, nor will it cause lithium precipitation due to lithium-nickel mixing. The electrochemical activity and cycle stability can be guaranteed as long as the PDD is maintained within a specific range, and the electrochemical performance of the doped positive electrode material will be better (for example, the electrochemical cycle stability of the positive electrode material doped with niobium will be improved).

[0042] Preferably, the mass content of particles with a diameter of 5 to 15 μm in the positive electrode material accounts for ≥50%.

[0043] Preferably, the specific surface area of ​​the positive electrode material is 5 to 15 m 2 / g.

[0044] After controlling the particle size, specific surface area and pore size of the positive electrode material, the particles are more evenly arranged after being prepared into a lithium electrode sheet, and the contact effect with the electrolyte is better.

[0045] Another object of the present invention is to provide a secondary battery comprising a positive electrode plate, a separator and a negative electrode plate; the positive electrode plate comprises the positive electrode material of the present invention.

[0046] When the positive electrode material of the present invention is applied to the positive electrode sheet in a secondary battery, its particle distribution as an active material is ideal, without extrusion or excessive inter-particle interface, and has high charge and discharge stability. There is no significant increase in lithium-nickel mixing, the probability of lithium precipitation is low, and the electrochemical performance is excellent. Furthermore, after being prepared into a positive electrode sheet, the PPD of the positive electrode material, the mixed site occupancy ratio of lithium atoms and nickel atoms, and the average number of primary particles per square micrometer of cross-section in secondary particles with a particle diameter of 5 to 15 μm do not change significantly. Based on this property, those skilled in the art can make relatively accurate predictions of the electrochemical performance of secondary batteries.

[0047] It should be noted that the negative electrode sheet and the separator in the secondary battery can be made of conventional materials in the art; the secondary battery can be prepared by conventional methods in the art.

[0048] Another object of the present invention is to provide an electrical device comprising the secondary battery of the present invention, wherein the secondary battery serves as a power supply for the electrical device.

[0049] Preferably, the electrical devices include cars, battery vehicles, ships and lighting lamps.

[0050] The beneficial effect of the present invention is that the present invention provides a high-nickel positive electrode material. By limiting the product of parameter A and parameter B of the product to a specific range, the primary particles in the secondary particles in the product will not be arranged too tightly to cause the risk of extrusion and crushing, and at the same time, sufficient transmission space can be provided for lithium ion intercalation and deintercalation; the product will not cause lithium precipitation problems due to lithium and nickel mixing during the charge and discharge process, and therefore has ideal charge and discharge activity and cycle stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is a scanning electron microscope image of the overall material of the positive electrode material obtained in Example 1a-1 of the present invention (left), a scanning electron microscope image of the secondary particles of 5 to 15 μm in the material (middle), and a scanning electron microscope image of the primary particles in the secondary particles of 5 to 15 μm in the material (right).

[0052] FIG2 is a spectrum of the fitting and modification results of the positive electrode material obtained in Example 1a-1 of the present invention obtained by fitting and modification by analysis software after XRD test.

[0053] Figure 3 is a scanning electron microscope image of the overall material of the positive electrode material obtained in Example 1a-2 of the present invention (left), a scanning electron microscope image of the secondary particles of 5 to 15 μm in the material (middle), and a scanning electron microscope image of the primary particles in the secondary particles of 5 to 15 μm in the material (right).

[0054] Figure 4 is a scanning electron microscope image of the overall material of the positive electrode material obtained in Example 1a-4 of the present invention (left), a scanning electron microscope image of the secondary particles of 5 to 15 μm in the material (middle), and a scanning electron microscope image of the primary particles in the secondary particles of 5 to 15 μm in the material (right).

[0055] FIG5 is a spectrum of analysis software fitting and modification results obtained by fitting and modification by analysis software after XRD test of the positive electrode material obtained in Example 1a-4 of the present invention.

[0056] Figure 6 is a scanning electron microscope image of the overall material of the positive electrode material obtained in Example 1a-6 of the present invention (left), a scanning electron microscope image of the secondary particles of 5 to 15 μm in the material (middle), and a scanning electron microscope image of the primary particles in the secondary particles of 5 to 15 μm in the material (right).

[0057] Figure 7 is a scanning electron microscope image of the overall material of the positive electrode material obtained in Example 1a-7 of the present invention (left), a scanning electron microscope image of the secondary particles of 5 to 15 μm in the material (middle), and a scanning electron microscope image of the primary particles in the secondary particles of 5 to 15 μm in the material (right).

[0058] Figure 8 is a scanning electron microscope image of the overall material of the positive electrode material obtained in Examples 1a-10 of the present invention (left), a scanning electron microscope image of the secondary particles of 5 to 15 μm in the material (middle), and a scanning electron microscope image of the primary particles in the secondary particles of 5 to 15 μm in the material (right).

[0059] Figure 9 is a scanning electron microscope image of the overall material of the positive electrode material obtained in Examples 1a-12 of the present invention (left), a scanning electron microscope image of the secondary particles of 5 to 15 μm in the material (middle), and a scanning electron microscope image of the primary particles in the secondary particles of 5 to 15 μm in the material (right).

[0060] Figure 10 is a scanning electron microscope image of the overall material of the positive electrode material obtained in Examples 1a-13 of the present invention (left), a scanning electron microscope image of the secondary particles of 5 to 15 μm in the material (middle), and a scanning electron microscope image of the primary particles in the secondary particles of 5 to 15 μm in the material (right).

[0061] FIG11 is a spectrum of analysis software fitting and modification results obtained by fitting and modification by analysis software after XRD test of the positive electrode materials obtained in Examples 1a-13 of the present invention.

[0062] Figure 12 is a scanning electron microscope image of the secondary particles of 5 to 15 μm in the positive electrode material obtained in Example 1a-1 of the present invention (left), a cross-sectional fitting diagram of the particles after cutting (middle), and a primary particle distribution diagram fitted by software (right).

[0063] Figure 13 is a scanning electron microscope image of the secondary particles of 5 to 15 μm in the positive electrode material obtained in Examples 1a-4 of the present invention (left), a cross-sectional fitting diagram of the particles after cutting (middle), and a primary particle distribution diagram fitted by software (right).

[0064] Figure 14 is a scanning electron microscope image of the secondary particles of 5 to 15 μm in the positive electrode materials obtained in Examples 1a-13 of the present invention (left), a cross-sectional fitting diagram of the particles after cutting (middle), and a primary particle distribution diagram fitted by software (right).

[0065] FIG15 is a statistical spherical graph of the data of the positive electrode material obtained in Example 1 of the present invention after charge and discharge tests. DETAILED DESCRIPTION

[0066] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments and comparative examples. Its purpose is to understand the content of the present invention in detail, rather than to limit the present invention. All other embodiments obtained by those of ordinary skill in the art without making creative work premise belong to the protection scope of the present invention. The experimental reagents, raw materials and instruments designed for the implementation of the present invention and the comparative examples are all conventional common reagents, raw materials and instruments unless otherwise specified.

[0067] It should be noted that the terms "include", "comprising" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units that are not listed, or may optionally include other steps or units that are inherent to these processes, methods, products or devices. In the claims, specifications and drawings of the present invention, relational terms such as "first" and "second" are merely used to distinguish one entity / operation / object from another entity / operation / object, and do not necessarily require or imply any actual relationship or order between these entities / operations / objects.

[0068] In the present invention, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0069] In the present invention, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Furthermore, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0070] The present invention provides a high nickel cathode material, comprising nickel and lithium elements, wherein the cathode material comprises primary particles and secondary particles formed by stacking the primary particles, and the cathode material satisfies: 20≤A*B≤50

[0071] Wherein A is the mixed occupancy ratio of lithium atoms and nickel atoms in the positive electrode material, and B is the average number of primary particles per square micrometer cross section in secondary particles with a particle diameter of 5 to 15 μm in the positive electrode material.

[0072] Specifically, A*B can be a range value of one or any two of 20, 25, 30, 35, 40, 45, 50.

[0073] In one preferred embodiment, the mixed site ratio of lithium atoms and nickel atoms in the positive electrode material is 1.2-5.

[0074] Specifically, the mixed site ratio of lithium atoms and nickel atoms in the positive electrode material can be in the range of one or any two of 1.2, 1.5, 1.8, 2, 2.5, 3, 3.5, 4, 4.5, 5.

[0075] In one preferred embodiment, the average number of primary particles per square micrometer of cross section in the secondary particles with a particle diameter of 5 to 15 μm in the positive electrode material is 4 to 25.

[0076] Specifically, the average number of primary particles per square micrometer of cross section in the secondary particles with a particle diameter of 5 to 15 μm in the positive electrode material can be in the range of one or any two of 4, 8, 10, 12, 15, 18, 20, 22, and 25.

[0077] In the embodiments, the values ​​of A and B are rounded to two decimal places, and A*B is rounded to two decimal places for the convenience of statistics and calculations. Those skilled in the art should be aware that if other values ​​or calculation methods are used for calculation, there will inevitably be certain numerical deviations, but such deviations are predictable to those skilled in the art and will not affect the reliability of the limited value range of PPD described in the present invention.

[0078] In one preferred embodiment, the mass content of particles with a diameter of 5 to 15 μm in the positive electrode material accounts for ≥50%.

[0079] In one preferred embodiment, the specific surface area of ​​the positive electrode material is 5 to 15 m 2 / g.

[0080] An embodiment of the present invention provides a secondary battery, comprising a positive electrode plate, a separator, and a negative electrode plate; the positive electrode plate comprises the positive electrode material of the present invention.

[0081] An embodiment of the present invention provides an electric device, comprising the secondary battery of the present invention, wherein the secondary battery serves as a power supply for the electric device.

[0082] Specifically, in an embodiment of the present invention, the positive electrode material includes LiNi x M 1-x O2 or LiNi y Co z M' 1-y-z O2;

[0083] The M is any one of Co, Mn, and Mg, and 0.7≤x≤0.98;

[0084] The M' is any one of Mn, Mg, and Al, 0.7≤y≤0.98, 0.05≤z≤0.3, and y+z<1.

[0085] Further preferably, the LiNi x M 1-x In O2, 0.9≤x≤0.98;

[0086] Further preferably, the LiNi y Co z M' 1-y-z In O2, 0.8≤y≤0.95;

[0087] Further preferably, the LiNi y Co z M' 1-y-z In O2, 0.9≤y≤0.95;

[0088] The positive electrode material is LiNi 0.9 M 0.1 O2、LiNi 0.95 M 0.05 O2、LiNi 0.98 M 0.02 O2、LiNi 0.8 Co z N 0.2-z O2、LiNi0.9 Co z N 0.1-z O2 or LiNi 0.95 Co z N 0.05-z O2;

[0089] Further preferably, the positive electrode material further includes a doping element, and the doping element is at least one of niobium, tungsten, molybdenum, tantalum, titanium, zirconium, boron, aluminum, and magnesium.

[0090] Further preferably, the doping element is niobium.

[0091] In one embodiment, the positive electrode material is LiNi 0.9 M 0.1 O2.

[0092] In one embodiment, the positive electrode material includes doping elements niobium and LiNi 0.9 M 0.1 O2, the doping amount of the doping element niobium is 0.5-5%.

[0093] In one embodiment, the positive electrode material is LiNi 0.95 M 0.05 O2.

[0094] In one embodiment, the positive electrode material includes doping elements niobium and LiNi 0.95 M 0.05 O2, the doping amount of the doping element niobium is 0.5-5%.

[0095] In one embodiment, the positive electrode material is LiNi 0.98 M 0.02 O2.

[0096] In one embodiment, the positive electrode material includes doping elements niobium and LiNi 0.98 M 0.02 O2, the doping amount of the doping element niobium is 0.5-5%. Specifically, the doping amount of the doping element niobium can be in the range of one or any two of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, and 5%.

[0097] In one embodiment, the positive electrode material is LiNi 0.8 Co 0.1 M' 0.1 O2.

[0098] In one embodiment, the positive electrode material includes doping elements niobium and LiNi 0.8 Co 0.1 M' 0.1O2, the doping amount of the doping element niobium is 0.5-5%.

[0099] In one embodiment, the positive electrode material is LiNi 0.9 Co 0.05 M' 0.05 O2.

[0100] In one embodiment, the positive electrode material includes doping elements niobium and LiNi 0.9 Co 0.05 M 0.05 O2, the doping amount of the doping element niobium is 0.5-5%.

[0101] In one embodiment, the positive electrode material is LiNi 0.95 Co 0.025 M' 0.025 O2.

[0102] In one embodiment, the positive electrode material includes doping elements niobium and LiNi 0.95 Co 0.025 M' 0.025 O2, the doping amount of the doping element niobium is 0.5-5%.

[0103] Specifically, the doping amount of the doping element niobium can be within the range of one or any two of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, and 5%.

[0104] The specific surface area of ​​the positive electrode materials prepared in each embodiment was detected to be 5 to 15 m 2 / g range.

[0105] The present invention is further described below with specific embodiments:

[0106] Example 1

[0107] A positive electrode material, the preparation method comprising the following steps:

[0108] (1) NiSO4·6H2O, CoSO4·H2O, and MnSO4·H2O were weighed and dissolved in deionized water at a molar ratio of 9:0.5:0.5 to prepare a 1.5-2.5 mol / L solution. At the same time, 3-5 mol / L NaOH solution and 3-5 mol / L ammonia solution were prepared.

[0109] (2) The solutions prepared in step (1) were dripped into the reactor through a peristaltic pump for coprecipitation reaction, and the pH of the mixed solution was accurately controlled to be 11-12 by regulating the flow rate of the NaOH solution. The reaction temperature was controlled to be 50° C. by heating in a water bath, and the reaction was stirred at a rate of 800 rpm. Nitrogen was introduced for protection, and the reaction was continued for 5-6 hours, followed by aging for 12 hours, washing, and drying to obtain a coprecipitation precursor;

[0110] (3) The coprecipitated precursor and LiOH·H2O were mixed and ground evenly in a molar ratio of 1:(1.06-1.1), and then placed in a tube furnace under a normal pressure oxygen atmosphere (1 atm) and preheated to 500°C for 4-6 hours, then heated to X°C for 14-16 hours, and cooled to obtain the positive electrode material LiNi 0.9 Co 0.05 Mn 0.05 O2.

[0111] Among them, according to the different temperatures X℃ of the second-stage insulation, Examples 1a-1 to 1a-13 are set in parallel. In these examples, X℃ is 700℃, 710℃, 720℃, 725℃, 730℃, 740℃, 750℃, 760℃, 770℃, 775℃, 780℃, 790℃ and 800℃, respectively.

[0112] The mixed occupancy ratio A of lithium atoms and nickel atoms of the positive electrode materials prepared in Examples 1a-1 to 1a-13 was statistically analyzed: the positive electrode materials were subjected to XRD detection to obtain a spectrum, and then the spectrum was fitted and modified using TOPAS XRD spectrum analysis software to obtain relevant values.

[0113] The average number B of primary particles per square micrometer of cross-section in secondary particles with a particle diameter of 5 to 15 μm prepared in the positive electrode materials of Examples 1-1 to 1-13 was calculated: 50 samples of the positive electrode material containing secondary particles with a diameter of 5 to 15 μm were taken, and then the samples were sectioned using a focused ion beam. The sectioned sample was then examined by scanning electron microscope (SEM) to obtain a cross-sectional SEM image of the sample. In the cross-sectional SEM image of the sample, the number of primary particles and the area of ​​each primary particle were counted using the pattern recognition software Dragonfly, and the average value was finally calculated.

[0114] The A and B of the products obtained in each example were used for the statistics of A*B, i.e., PPD.

[0115] The positive electrode materials prepared in Examples 1a-1 to 1a-13 were prepared in parallel into positive electrode sheets for lithium-ion batteries. The preparation process was as follows: the positive electrode material, PVDF (polyvinylidene fluoride), and commercial conductive carbon black were mixed in a mass ratio of 8:1:1 and slurried with NMP (N-methylpyrrolidone). The mixture was then coated, dried, rolled, and punched to obtain positive electrode sheets.

[0116] Lithium-ion button cells were assembled using a positive electrode sheet, a lithium metal sheet, a commercial separator, and an electrolyte. Electrochemical performance tests were then conducted at a voltage of 2.75 to 4.3 V and a temperature of 45°C. Initially, the cells were cycled three times at 0.1C with a nominal specific capacity of 180 mAh / g. The initial discharge specific capacity was recorded. The rate was then increased to 1C for 200 cycles, and the capacity retention at the final cycle was calculated. The test results are shown in Table 1a.

[0117] Table 1a

[0118] As can be seen from Table 1a, as the temperature of the second-stage insulation is continuously increased from 700°C to 800°C, the mixed occupancy ratio A of lithium atoms and nickel atoms in the prepared positive electrode material gradually decreases while the chemical composition remains basically unchanged. The secondary particle size with a particle diameter of 5 to 15 μm in the material remains basically unchanged, but the primary particle size in the secondary particles gradually increases. As shown in Figures 1 to 11, the average number B of primary particles per square micron cross section is basically gradually decreasing, as shown in Figures 12 to 14. According to existing well-known theories, the electrochemical performance of the positive electrode material should be best when the mixed occupancy ratio A of lithium atoms and nickel atoms is smaller. However, in Examples 1a-1 to 1a-13, the first discharge specific capacity of the product of Example 1a-13, which has the smallest mixed occupancy ratio A of lithium atoms and nickel atoms, is maintained at a level that can reach the contact area. It is nearly 230mAh / g, but not the highest among all the products. At the same time, the capacity retention rate after 200 cycles at a 1C rate is only 35.1%, which is obviously inconsistent with theoretical teachings. This is because in the charge and discharge process, in addition to the mixed occupancy ratio of lithium atoms and nickel atoms, the material particle size and particle distribution also have a significant impact on the electrochemical activity of the positive electrode material. When the PPD of the positive electrode material is in the range of 20 to 50, the corresponding first discharge specific capacity of the products of Example 1a-3 to Example 1a-6 can be maintained at more than 200mAh / g. The most important thing is that the capacity retention rate of these products after 200 cycles can reach more than 86%, which is a huge gap with Example 1a-7 (PPD is less than 20). Especially when the PPD is in the range of 25 to 40, the discharge specific capacity and cycle stability of the product are at a high level. While the capacity retention of the products in Examples 1a-1 and 1a-2 is further improved compared to Examples 1a-3 through 1a-6, due to the large A and B ratios, the PPD exceeds 50, resulting in poor lithium-ion deintercalation and deintercalation activity in the cathode material and an initial discharge capacity of less than 200 mAh / g. The test results in Table 1a are plotted as a spherical line graph 15. Figure 15 more intuitively illustrates that the performance trends of the cathode materials described herein differ from those observed in conventional processing techniques and lithium-nickel mixing patterns.

[0119] Subsequently, the same coprecipitation precursor was prepared according to the above method, and the coprecipitation precursor and LiOH·H2O were mixed and ground evenly according to a molar ratio of 1: (1.06-1.1), and then placed in a high-pressure tube furnace under an oxygen atmosphere (50 atm) and preheated to 500 ° C for 4-6 hours, then heated to the second stage and cooled to obtain the positive electrode material LiNi 0.9 Co 0.05 Mn 0.05 O2.

[0120] Among them, Examples 1b-1 to 1b-6 were set up in parallel. In these examples, the difference in the preparation process was that the conditions of the two-stage insulation were 700°C (4 to 6h), 700°C (14 to 16h), 725°C (14 to 16h), 750°C (14 to 16h), 775°C (14 to 16h), and 800°C (14 to 16h), respectively.

[0121] The positive electrode materials were statistically analyzed and tested according to the above method, and the results are shown in Table 1b.

[0122] Table 1b

[0123] As can be seen from Table 1b, although the same raw materials are used, if the calcination conditions are adjusted, for example, the calcination treatment of the material in a high-pressure environment as described above, the physical properties of the positive electrode material obtained under different conditions will be different. Therefore, the optimal calcination temperature corresponding to the optimal electrochemical performance of the positive electrode material is also different from that under normal pressure. However, when the PPD of the product is within the range of 20 to 50, the product can still achieve ideal discharge specific capacity and cycle stability.

[0124] Example 2

[0125] A positive electrode material, the preparation method comprising the following steps:

[0126] (1) NiSO4·6H2O, CoSO4·H2O, and MnSO4·H2O were weighed and dissolved in deionized water at a molar ratio of 9.5:0.25:0.25 to prepare a 1.5-2.5 mol / L solution. At the same time, 3-5 mol / L NaOH solution and 3-5 mol / L ammonia solution were prepared.

[0127] (2) The solutions prepared in step (1) were dripped into the reactor through a peristaltic pump for coprecipitation reaction, and the pH of the mixed solution was accurately controlled to be 11-12 by regulating the flow rate of the NaOH solution. The reaction temperature was controlled to be 50° C. by heating in a water bath, and the reaction was stirred at a rate of 800 rpm. Nitrogen was introduced for protection, and the reaction was continued for 5-6 hours, followed by aging for 12 hours, washing, and drying to obtain a coprecipitation precursor;

[0128] (3) The coprecipitated precursor and LiOH·H2O were mixed and ground evenly in a molar ratio of 1: (1.06-1.1), and then placed in a tube furnace under a normal pressure oxygen atmosphere (1 atm) and preheated to 500°C for 4-6 hours, then heated for a second stage of insulation, and cooled to obtain the positive electrode material LiNi 0.95 Co 0.025 Mn 0.025 O2.

[0129] Among them, Examples 2a-1 to 2a-7 are set up in parallel. In these examples, the difference in the preparation process is that the conditions during the second-stage insulation are 700°C (14 to 16h), 700°C (74 to 76h), 700°C (149 to 151h), 725°C (14 to 16h), 750°C (14 to 16h), 775°C (14 to 16h), and 800°C (14 to 16h).

[0130] The positive electrode material was statistically analyzed and tested according to the method described in Example 1, with a nominal specific capacity of 180 mAh / g. The results are shown in Table 2a.

[0131] Table 2a

[0132] Subsequently, the same coprecipitation precursor was prepared according to the above method, and the coprecipitation precursor and LiOH·H2O were mixed and ground evenly according to a molar ratio of 1: (1.06-1.1), and then placed in a high-pressure tube furnace under an oxygen atmosphere (50 atm) and preheated to 500 ° C for 4-6 hours, then heated for two stages and cooled to obtain the positive electrode material LiNi 0.95 Co 0.025 Mn 0.025 O2.

[0133] Among them, Examples 2b-1 to 2b-6 were set up in parallel. In these examples, the difference in the preparation process was that the conditions of the two-stage insulation were 700°C (14 to 16h), 725°C (14 to 16h), 750°C (14 to 16h), 775°C (14 to 16h), 800°C (14 to 16h), and 850°C (14 to 16h), respectively.

[0134] The positive electrode material was statistically analyzed and tested according to the above method. The results are shown in Table 2b. It can be seen from the records in Table 2a and Table 2b that, compared with the example product, when the doping conditions are changed, the discharge specific capacity and cycle capacity retention rate of the product are changed, but the relationship between its performance and the PPD of the product is similar to that of the product in Example 1.

[0135] Table 2b

[0136] Example 3

[0137] A positive electrode material, the preparation method comprising the following steps:

[0138] (1) NiSO4·6H2O and MnSO4·H2O were weighed and dissolved in deionized water at a molar ratio of 9:1 to prepare a 1.5-2.5 mol / L solution. At the same time, 3-5 mol / L NaOH solution and 3-5 mol / L ammonia solution were prepared.

[0139] (2) adding each solution prepared in step (1) into a reactor through a peristaltic pump to carry out a coprecipitation reaction, and precisely controlling the pH of the mixed solution to 8-10 by regulating the flow rate of the NaOH solution, controlling the reaction temperature to 50°C by heating in a water bath, stirring the reaction at a rate of 800 rpm, introducing nitrogen for protection, and continuously reacting for 5-6 hours, followed by aging for 12 hours, washing, and drying to obtain a coprecipitation precursor;

[0140] (3) The coprecipitated precursor and Li2CO3 are mixed and ground evenly in a molar ratio of 1: (0.5-0.55), and then placed in a tube furnace under a normal pressure oxygen atmosphere (1 atm) and preheated to 500 ° C for 4-6 hours, then heated for a second stage of insulation and cooled to obtain the positive electrode material LiNi 0.9 Mn 0.1 O2.

[0141] Among them, Examples 3-1 to 3-6 were set up in parallel. In these examples, the only difference in the preparation process was that the conditions of the second-stage insulation were 725°C (14 to 16h), 750°C (14 to 16h), 750°C (74 to 76h), 775°C (14 to 16h), 800°C (14 to 16h), and 825°C (14 to 16h).

[0142] The positive electrode material was statistically analyzed and tested according to the method described in Example 1, with a nominal specific capacity of 180 mAh / g. The results are shown in Table 3. Unlike Examples 1 and 2, the product prepared in this example is a binary material. However, similar to Examples 1 and 2, the product can only achieve high discharge specific capacity and cycle capacity retention when the PPD is maintained in the range of 20 to 50.

[0143] Table 3

[0144] Example 4

[0145] A positive electrode material, the preparation method comprising the following steps:

[0146] (1) NiSO4·6H2O and MgSO4·7H2O were weighed and dissolved in deionized water at a molar ratio of 9.5:0.5 to prepare a 1.5-2.5 mol / L solution. At the same time, 3-5 mol / L NaOH solution and 4 mol / L ammonia solution were prepared.

[0147] (2) adding each solution prepared in step (1) into a reactor through a peristaltic pump to carry out a coprecipitation reaction, and precisely controlling the pH of the mixed solution to 8-10 by regulating the flow rate of the NaOH solution, controlling the reaction temperature to 50°C by heating in a water bath, stirring the reaction at a rate of 800 rpm, introducing nitrogen for protection, and continuously reacting for 5-6 hours, followed by aging for 12 hours, washing, and drying to obtain a coprecipitation precursor;

[0148] (3) The coprecipitated precursor and Li2CO3 are mixed and ground evenly in a molar ratio of 1: (0.5-0.55), and then placed in a tube furnace under a normal pressure oxygen atmosphere (1 atm) and preheated to 500 ° C for 4-6 hours, then heated for a second stage of insulation and cooled to obtain the positive electrode material LiNi 0.95 Mn 0.05 O2.

[0149] Among them, Examples 4a-1 to 4a-7 were set up in parallel. In these examples, the only difference in the preparation process was that the conditions of the two-stage insulation were 700°C (14 to 16h), 725°C (14 to 16h), 750°C (14 to 16h), 750°C (74 to 76h), 775°C (14 to 16h), 800°C (14 to 16h), and 825°C (14 to 16h).

[0150] The positive electrode material was statistically analyzed and tested according to the method described in Example 1, with a nominal specific capacity of 180 mAh / g. The results are shown in Table 4a.

[0151] Table 4a

[0152] Subsequently, the same coprecipitation precursor was prepared according to the above method, and the coprecipitation precursor and Li2CO3 were mixed and ground evenly according to a molar ratio of 1: (0.5-0.55), and then placed in a high-pressure tube furnace under an oxygen atmosphere (50 atm) and preheated to 500 ° C for 4-6 hours, and then heated for two stages of insulation and cooled to obtain the positive electrode material LiNi 0.95 Mn 0.05 O2.

[0153] Among them, Examples 4b-1 to 4b-8 were set up in parallel. In these examples, the only difference in the preparation process was that the conditions of the two-stage insulation were 700°C (14 to 16h), 725°C (14 to 16h), 750°C (14 to 16h), 750°C (74 to 76h), 775°C (14 to 16h), 800°C (14 to 16h), 825°C (14 to 16h), and 850°C (14 to 16h).

[0154] The positive electrode material was statistically analyzed and tested according to the method described in Example 1. The results are shown in Table 4b.

[0155] Table 4b

[0156] It can be seen from Tables 4a and 4b that when the composition of the positive electrode material is different from that of Example 1, as the calcination temperature conditions increase and the pressure conditions change, the initial size and change range of the mixed occupancy ratio A of lithium atoms and nickel atoms in the positive electrode material and the average number B of primary particles per square micron cross-section in secondary particles with a particle diameter of 5 to 15 μm also vary. However, only when the PPD is in the range of 20 to 50 can the obtained positive electrode material have both ideal discharge specific capacity and cycle stability.

[0157] Example 5

[0158] A positive electrode material, the preparation method comprising the following steps:

[0159] (1) NiSO4·6H2O and MgSO4·7H2O were weighed and dissolved in deionized water at a molar ratio of 9.8:0.2 to prepare a 1.5-2.5 mol / L solution. At the same time, 3-5 mol / L NaOH solution and 3-5 mol / L ammonia solution were prepared.

[0160] (2) The solutions prepared in step (1) were dripped into the reactor through a peristaltic pump for coprecipitation reaction. The pH of the mixed solution was accurately controlled to be 8-10 by regulating the flow rate of the NaOH solution. The reaction temperature was controlled to be 50° C. by heating in a water bath. The reaction was stirred and the speed was controlled to be 800 rpm. Nitrogen was introduced for protection. The reaction was continued for 6 h, followed by aging for 12 h, washing, and drying to obtain a coprecipitation precursor.

[0161] (3) The coprecipitated precursor and Li2CO3 are mixed and ground evenly in a molar ratio of 1: (0.5-0.55), and then placed in a tube furnace under a normal pressure oxygen atmosphere (1 atm) and preheated to 500 ° C for 4-6 hours, then heated for a second stage of insulation and cooled to obtain the positive electrode material LiNi 0.98 Mn 0.02 O2. Among them, Examples 5a-1 to 5a-7 were respectively prepared in parallel, and the only difference in the preparation processes among these examples was that the conditions of the second-stage insulation were 700°C (14-16h), 725°C (14-16h), 750°C (14-16h), 750°C (74-76h), 750°C (149-151h), 775°C (14-16h), and 800°C (14-16h), respectively.

[0162] The positive electrode material was statistically analyzed and tested according to the method described in Example 1, with a nominal specific capacity of 180 mAh / g. The results are shown in Table 5a.

[0163] Table 5a

[0164] Subsequently, the same coprecipitation precursor was prepared according to the above method, and the coprecipitation precursor and Li2CO3 were mixed and ground evenly according to a molar ratio of 1: (0.5-0.55), and then placed in a high-pressure tube furnace under an oxygen atmosphere (50 atm) and preheated to 500 ° C for 4-6 hours, and then heated for two stages of insulation and cooled to obtain the positive electrode material LiNi 0.98 Mn 0.02 O2.

[0165] Among them, Examples 5b-1 to 5b-8 were set up in parallel. In these examples, the only difference in the preparation process was that the conditions of the two-stage insulation were 700°C (14 to 16h), 725°C (14 to 16h), 750°C (14 to 16h), 775°C (14 to 16h), 775°C (74 to 76h), 800°C (14 to 16h), 825°C (14 to 16h), and 800°C (14 to 16h).

[0166] The positive electrode material was statistically analyzed and tested according to the method described in Example 1. The results are shown in Table 5b.

[0167] Table 5b

[0168] Example 6

[0169] A positive electrode material, the preparation method comprising the following steps:

[0170] (1) NiSO4·6H2O, CoSO4·H2O, and MnSO4·H2O were weighed and dissolved in deionized water at a molar ratio of 9:0.5:0.5 to prepare a 1.5-2.5 mol / L solution. At the same time, 3-5 mol / L NaOH solution and 3-5 mol / L ammonia solution were prepared.

[0171] (2) The solutions prepared in step (1) were dripped into the reactor through a peristaltic pump for coprecipitation reaction, and the pH of the mixed solution was accurately controlled to be 11-12 by regulating the flow rate of the NaOH solution. The reaction temperature was controlled to be 50° C. by heating in a water bath, and the reaction was stirred at a rate of 800 rpm. Nitrogen was introduced for protection, and the reaction was continued for 5-6 hours, followed by aging for 12 hours, washing, and drying to obtain a coprecipitation precursor;

[0172] (3) The coprecipitated precursor and LiOH·H2O were mixed in a molar ratio of 1:(1.06-1.1), and then niobium pentoxide was added and ground evenly. The mixture was then placed in a tube furnace under a normal pressure oxygen atmosphere (1 atm) and preheated to 500°C for 4-6 hours, then heated for a second stage of heat preservation, and cooled to obtain the niobium-doped positive electrode material LiNi 0.9 Co 0.05 Mn 0.05 O2, the niobium doping amount in the niobium-doped positive electrode material is 0.5% by mole percentage.

[0173] Among them, Examples 6-1 to 6-8 are set up in parallel. Among these examples, the only difference is that the conditions of the second-stage insulation are 700℃ (14~16h), 725℃ (14~16h), 750℃ (14~16h), 725℃ (49~51h), 725℃ (74~76h), 725℃ (149~151h), 775℃ (14~16h), and 800℃ (14~16h).

[0174] The niobium-doped positive electrode material was statistically analyzed and tested according to the method described in Example 1, with a nominal specific capacity of 180 mAh / g. The results are shown in Table 6.

[0175] Table 6

[0176] It can be seen that in this embodiment, the changes in parameters A and B are not positively correlated with the holding temperature of the product. When maintained at 725°C, as the holding time increases, the values ​​of parameters A and B may be higher than those at 750°C. At the same time, it can be seen from Table 6 that the positive electrode material of the present invention may also contain doping elements, such as the doping element niobium in this embodiment, which effectively penetrates into the material lattice and has a certain impact on the various physical properties of the material. However, in each embodiment, only products whose PPD meets the defined range of the present invention can have ideal electrochemical performance. Due to the doping of niobium, the above-mentioned embodiment products that meet the definition of the present invention can still maintain a considerable discharge specific capacity after further long-term cycling. For example, after further cycling to 500 times, the cycle capacity retention rate of the product of Example 6-5 can still reach 95%.

[0177] Example 7

[0178] A positive electrode material, the preparation method comprising the following steps:

[0179] (1) NiSO4·6H2O, CoSO4·H2O, and MnSO4·H2O were weighed and dissolved in deionized water at a molar ratio of 9:0.5:0.5 to prepare a 1.5-2.5 mol / L solution. At the same time, 3-5 mol / L NaOH solution and 3-5 mol / L ammonia solution were prepared.

[0180] (2) The solutions prepared in step (1) were dripped into the reactor through a peristaltic pump for coprecipitation reaction, and the pH of the mixed solution was accurately controlled to be 11-12 by regulating the flow rate of the NaOH solution. The reaction temperature was controlled to be 50° C. by heating in a water bath, and the reaction was stirred at a rate of 800 rpm. Nitrogen was introduced for protection, and the reaction was continued for 5-6 hours, followed by aging for 12 hours, washing, and drying to obtain a coprecipitation precursor;

[0181] (3) The coprecipitated precursor and LiOH·H2O were mixed in a molar ratio of 1:(1.06-1.1), and then niobium pentoxide was added and ground evenly. The mixture was then placed in a tube furnace under a normal pressure oxygen atmosphere (1 atm) and preheated to 500°C for 4-6 hours, then heated for a second stage of heat preservation, and cooled to obtain the niobium-doped positive electrode material LiNi 0.9 Co 0.05 Mn 0.05 O2, the niobium doping amount in the niobium-doped positive electrode material is 1% by mole percentage.

[0182] Among them, according to the different conditions of the second-stage insulation, Examples 7-1 to 7-8 are set in parallel. In these examples, the conditions of the second-stage insulation are 700℃ (14~16h), 725℃ (14~16h), 750℃ (14~16h), 750℃ (49~51h), 750℃ (74~76h), 750℃ (149~151h), 775℃ (14~16h), and 800℃ (14~16h).

[0183] The niobium-doped positive electrode material was statistically analyzed and tested according to the method described in Example 1, with a nominal specific capacity of 180 mAh / g. The results are shown in Table 7.

[0184] Table 7

[0185] By comparing the products of Example 6 and Example 7, it can be seen that as the doping elements increase, the mixed occupancy ratio A of lithium atoms and nickel atoms in the positive electrode material after treatment at the same calcination temperature and the average number B of primary particles per square micrometer cross-section in secondary particles with a particle diameter of 5 to 15 μm are greatly different, indicating that the physical properties of the positive electrode material are also affected by the doping amount of the doping elements, and the corresponding calcination conditions when the primary particle distribution characteristic parameter PPD meets the limited range are also different.

[0186] Example 8

[0187] A positive electrode material, the preparation method comprising the following steps:

[0188] (1) NiSO4·6H2O, CoSO4·H2O, and MnSO4·H2O were weighed and dissolved in deionized water at a molar ratio of 9.5:0.25:0.25 to prepare a 1.5-2.5 mol / L solution. At the same time, 3-5 mol / L NaOH solution and 3-5 mol / L ammonia solution were prepared.

[0189] (2) The solutions prepared in step (1) were dripped into the reactor through a peristaltic pump for coprecipitation reaction, and the pH of the mixed solution was accurately controlled to be 11-12 by regulating the flow rate of the NaOH solution. The reaction temperature was controlled to be 50° C. by heating in a water bath, and the reaction was stirred at a rate of 800 rpm. Nitrogen was introduced for protection, and the reaction was continued for 5-6 hours, followed by aging for 12 hours, washing, and drying to obtain a coprecipitation precursor;

[0190] (3) The coprecipitated precursor and LiOH·H2O were mixed in a molar ratio of 1:(1.06-1.1), and then niobium pentoxide was added and ground evenly. The mixture was then placed in a tube furnace under a normal pressure oxygen atmosphere (1 atm) and preheated to 500°C for 4-6 hours, then heated for a second stage of heat preservation, and cooled to obtain the niobium-doped positive electrode material LiNi 0.95 Co 0.025 Mn 0.025 O2, the niobium doping amount in the niobium-doped positive electrode material is 0.5% by mole percentage.

[0191] Among them, according to the different conditions of the second-stage insulation, Examples 8-1 to 8-7 are set in parallel. In these examples, the conditions of the second-stage insulation are 700℃ (14~16h), 725℃ (14~16h), 750℃ (14~16h), 750℃ (49~51h), 775℃ (14~16h), 800℃ (14~16h), and 825℃ (14~16h).

[0192] The niobium-doped positive electrode material was statistically analyzed and tested according to the method described in Example 1, with a nominal specific capacity of 180 mAh / g. The results are shown in Table 8.

[0193] Table 8

[0194] Example 9

[0195] A positive electrode material, the preparation method comprising the following steps:

[0196] (1) NiSO4·6H2O, CoSO4·H2O, and MnSO4·H2O were weighed and dissolved in deionized water at a molar ratio of 9.5:0.25:0.25 to prepare a 1.5-2.5 mol / L solution. At the same time, 3-5 mol / L NaOH solution and 3-5 mol / L ammonia solution were prepared.

[0197] (2) The solutions prepared in step (1) were dripped into the reactor through a peristaltic pump for coprecipitation reaction, and the pH of the mixed solution was accurately controlled to be 11-12 by regulating the flow rate of the NaOH solution. The reaction temperature was controlled to be 50° C. by heating in a water bath, and the reaction was stirred at a rate of 800 rpm. Nitrogen was introduced for protection, and the reaction was continued for 5-6 hours, followed by aging for 12 hours, washing, and drying to obtain a coprecipitation precursor;

[0198] (3) The coprecipitated precursor and LiOH·H2O were mixed in a molar ratio of 1:(1.06-1.1), and then niobium pentoxide was added and ground evenly. The mixture was then placed in a tube furnace under a normal pressure oxygen atmosphere (1 atm) and preheated to 500°C for 4-6 hours, then heated for a second stage of heat preservation, and cooled to obtain the niobium-doped positive electrode material LiNi 0.95 Co 0.025 Mn 0.025 O2, the niobium doping amount in the niobium-doped positive electrode material is 1% by mole percentage.

[0199] Among them, according to the different conditions of the second-stage insulation, Examples 9-1 to 9-6 are set in parallel. In these examples, X℃ is 700℃ (14~16h), 725℃ (14~16h), 725℃ (49~51h), 750℃ (14~16h), 775℃ (14~16h) and 800℃ (14~16h).

[0200] The niobium-doped positive electrode material was statistically analyzed and tested according to the method described in Example 1, with a nominal specific capacity of 180 mAh / g. The results are shown in Table 9.

[0201] Table 9

[0202] Example 10

[0203] A positive electrode material, the preparation method comprising the following steps:

[0204] (1) NiSO4·6H2O and MnSO4·H2O were weighed and dissolved in deionized water at a molar ratio of 9:1 to prepare a 1.5-2.5 mol / L solution. At the same time, 3-5 mol / L NaOH solution and 3-5 mol / L ammonia solution were prepared.

[0205] (2) adding each solution prepared in step (1) into a reactor through a peristaltic pump to carry out a coprecipitation reaction, and precisely controlling the pH of the mixed solution to 8-10 by regulating the flow rate of the NaOH solution, controlling the reaction temperature to 50°C by heating in a water bath, stirring the reaction at a rate of 800 rpm, introducing nitrogen for protection, and continuously reacting for 5-6 hours, followed by aging for 12 hours, washing, and drying to obtain a coprecipitation precursor;

[0206] (3) The coprecipitated precursor and Li2CO3 were mixed and ground in a molar ratio of 1: (0.5-0.55), and then niobium pentoxide was added and ground evenly. The mixture was then placed in a high-pressure tube furnace under an oxygen atmosphere (50 atm) and preheated to 500 ° C. for 4-6 hours, and then heated for two stages of heat preservation and cooled to obtain the niobium-doped positive electrode material LiNi 0.9 Mn 0.1 O2, the niobium doping amount in the niobium-doped positive electrode material is 0.5% by mole percentage.

[0207] Among them, Examples 10-1 to 10-7 were set up in parallel. In these examples, the only difference in the preparation process was that the conditions of the second-stage insulation were 725°C (14 to 16h), 750°C (14 to 16h), 775°C (14 to 16h), 800°C (14 to 16h), 800°C (49 to 51h), 825°C (14 to 16h), and 850°C (14 to 16h).

[0208] The niobium-doped positive electrode material was statistically analyzed and tested according to the method described in Example 1, with a nominal specific capacity of 180 mAh / g. The results are shown in Table 10.

[0209] Table 10

[0210] Comparing the products obtained in Example 3 and Example 10, it can be seen that compared with the undoped positive electrode material LiNi 0.9 Mn 0.1 O2 is similar to the doped cathode material LiNi 0.9 Mg 0.1 When the calcination conditions of O2 are different, the mixed occupancy ratio A of lithium atoms and nickel atoms in the product at the same calcination temperature and the average number B of primary particles per square micron cross-section in secondary particles with a particle diameter of 5 to 15 μm will also change. Only the products of Examples 10-4 to 10-6 that meet the requirements of the present invention have better performance.

[0211] Example 11

[0212] A positive electrode material, the preparation method comprising the following steps:

[0213] (1) NiSO4·6H2O and MnSO4·H2O were weighed and dissolved in deionized water at a molar ratio of 9.5:0.5 to prepare a 1.5-2.5 mol / L solution. At the same time, 3-5 mol / L NaOH solution and 3-5 mol / L ammonia solution were prepared.

[0214] (2) adding each solution prepared in step (1) into a reactor through a peristaltic pump to carry out a coprecipitation reaction, and precisely controlling the pH of the mixed solution to 8-10 by regulating the flow rate of the NaOH solution, controlling the reaction temperature to 50° C. by heating in a water bath, stirring the reaction at a rate of 800 rpm, introducing nitrogen for protection, and continuously reacting for 4-6 hours, followed by aging for 12 hours, washing, and drying to obtain a coprecipitation precursor;

[0215] (3) The coprecipitated precursor and Li2CO3 were mixed and ground in a molar ratio of 1: (0.5-0.55), and then niobium pentoxide was added and ground evenly. The mixture was then placed in a high-pressure tube furnace under an oxygen atmosphere (50 atm) and preheated to 500 ° C. for 4-6 hours, and then heated for two stages of heat preservation and cooled to obtain the niobium-doped positive electrode material LiNi 0.95 Mn 0.05 O2, the niobium doping amount in the niobium-doped positive electrode material is 0.5% by mole percentage.

[0216] Among them, Examples 11-1 to 11-8 were set up in parallel. In these examples, the only difference in the preparation process was that the conditions of the second-stage insulation were 725°C (14-16h), 750°C (14-16h), 775°C (14-16h), 800°C (14-16h), 800°C (74-76h), 800°C (149-151h), 825°C (14-16h), and 850°C (14-16h).

[0217] The niobium-doped positive electrode material was statistically analyzed and tested according to the method described in Example 1, with a nominal specific capacity of 180 mAh / g. The results are shown in Table 11.

[0218] Table 11

[0219] Example 12

[0220] A positive electrode material, the preparation method comprising the following steps:

[0221] (1) NiSO4·6H2O and CoSO4·H2O were weighed and dissolved in deionized water at a molar ratio of 9:1 to prepare a 1.5-2.5 mol / L solution. At the same time, 3-5 mol / L NaOH solution and 3-5 mol / L ammonia solution were prepared.

[0222] (2) adding each solution prepared in step (1) into a reactor through a peristaltic pump to carry out a coprecipitation reaction, and precisely controlling the pH of the mixed solution to 8-10 by regulating the flow rate of the NaOH solution, controlling the reaction temperature to 50° C. by heating in a water bath, stirring the reaction at a rate of 800 rpm, introducing nitrogen for protection, and continuously reacting for 4-6 hours, followed by aging for 12 hours, washing, and drying to obtain a coprecipitation precursor;

[0223] (3) The coprecipitated precursor and LiOH·H2O were mixed and ground evenly in a molar ratio of 1: (1.05-1.1), and then placed in a tube furnace under a normal pressure oxygen atmosphere (1 atm) and preheated to 500 ° C. for 4-6 hours, then heated for a second stage of heat preservation and cooled to obtain the positive electrode material LiNi 0.9 Co 0.1 O2.

[0224] Among them, Examples 12-1 to 12-6 were set up in parallel. In these examples, the only difference in the preparation process was that the conditions of the two-stage insulation were 700°C (14 to 16h), 725°C (14 to 16h), 725°C (49 to 51h), 750°C (14 to 16h), 775°C (14 to 16h), and 800°C (14 to 16h).

[0225] The positive electrode material was statistically analyzed and tested according to the method described in Example 1, with a nominal specific capacity of 180 mAh / g. The results are shown in Table 12.

[0226] Table 12

[0227] Example 13

[0228] A positive electrode material, the preparation method comprising the following steps:

[0229] (1) NiSO4·6H2O, CoSO4·H2O, and MnSO4·H2O were weighed and dissolved in deionized water at a molar ratio of 8:1:1 to prepare a 1.5-2.5 mol / L solution. A 3-5 mol / L NaOH solution and a 3-5 mol / L ammonia solution were also prepared.

[0230] (2) The solutions prepared in step (1) were dripped into the reactor through a peristaltic pump for coprecipitation reaction, and the pH of the mixed solution was accurately controlled to be 11-12 by regulating the flow rate of the NaOH solution. The reaction temperature was controlled to be 50° C. by heating in a water bath, and the reaction was stirred at a rate of 800 rpm. Nitrogen was introduced for protection, and the reaction was continued for 5-6 hours, followed by aging for 12 hours, washing, and drying to obtain a coprecipitation precursor;

[0231] (3) The coprecipitated precursor and LiOH·H2O were mixed and ground evenly in a molar ratio of 1: (1.06-1.1), and then placed in a tube furnace under a normal pressure oxygen atmosphere (1 atm) and preheated to 500°C for 4-6 hours, then heated for a second stage of insulation, and cooled to obtain the positive electrode material LiNi 0.8 Co 0.1 Mn 0.1 O2.

[0232] Among them, Examples 13a-1 to 13a-6 were set up in parallel. Among these examples, the only difference in the preparation process was that the conditions of the second-stage insulation were 725°C (14 to 16h), 750°C (14 to 16h), 750°C (74 to 76h), 775°C (14 to 16h), 800°C (14 to 16h), and 825°C (14 to 16h), respectively.

[0233] The positive electrode material was statistically analyzed and tested according to the method described in Example 1, with a nominal specific capacity of 180 mAh / g. The results are shown in Table 13a.

[0234] Table 13a

[0235] Subsequently, the same coprecipitation precursor was prepared according to the above method, and the coprecipitation precursor and LiOH·H2O were mixed and ground evenly according to a molar ratio of 1: (1.06-1.1), and then placed in a high-pressure tube furnace under an oxygen atmosphere (50 atm) and preheated to 500 ° C for 4-6 hours, then heated for two stages and cooled to obtain the positive electrode material LiNi 0.8 Co 0.1 Mn 0.1 O2.

[0236] Among them, Examples 13b-1 to 13b-8 were set up in parallel. In these examples, the only difference in the preparation process was that the conditions of the two-stage insulation were 725°C (14 to 16h), 750°C (14 to 16h), 750°C (74 to 76h), 775°C (14 to 16h), 775°C (74 to 76h), 800°C (14 to 16h), 825°C (14 to 16h), and 850°C (14 to 16h).

[0237] The positive electrode materials were statistically analyzed and tested according to the above method, and the results are shown in Table 13b.

[0238] Table 13b

[0239] Example 14

[0240] A positive electrode material, the preparation method comprising the following steps:

[0241] (1) NiSO4·6H2O, CoSO4·H2O, and MnSO4·H2O were weighed and dissolved in deionized water at a molar ratio of 8:1:1 to prepare a 1.5-2.5 mol / L solution. A 3-5 mol / L NaOH solution and a 3-5 mol / L ammonia solution were also prepared.

[0242] (2) The solutions prepared in step (1) were dripped into the reactor through a peristaltic pump for coprecipitation reaction, and the pH of the mixed solution was accurately controlled to be 11-12 by regulating the flow rate of the NaOH solution. The reaction temperature was controlled to be 50° C. by heating in a water bath, and the reaction was stirred at a rate of 800 rpm. Nitrogen was introduced for protection, and the reaction was continued for 4-6 hours, followed by aging for 12 hours, washing, and drying to obtain a coprecipitation precursor;

[0243] (3) The coprecipitated precursor and LiOH·H2O were mixed in a molar ratio of 1:(1.06-1.1), and then niobium pentoxide was added and ground evenly. The mixture was then placed in a tube furnace under a normal pressure oxygen atmosphere (1 atm) and preheated to 500°C for 4-6 hours, then heated for a second stage of heat preservation, and cooled to obtain the niobium-doped positive electrode material LiNi 0.8 Co 0.1 Mn 0.1 O2, the niobium doping amount in the niobium-doped positive electrode material is 2% by mole percentage.

[0244] Among them, Examples 14-1 to 14-8 were set up in parallel. In these examples, the only difference in the preparation process was that the conditions of the second-stage insulation were 725°C (14-16h), 750°C (14-16h), 775°C (14-16h), 800°C (14-16h), 800°C (74-76h), 800°C (149-151h), 825°C (14-16h), and 850°C (14-16h).

[0245] Table 14

[0246] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A cathode material, characterized in that, It contains lithium and nickel elements. The positive electrode material includes primary particles and secondary particles formed by stacking the primary particles, and the positive electrode material satisfies: 20 ≤ A * B ≤ 50; where A is the mixed occupation ratio of lithium atoms and nickel atoms in the positive electrode material, and B is the average number of primary particles per square micron of cross-section in secondary particles with a particle diameter of 5 - 15 μm in the positive electrode material.

2. The cathode material according to claim 1, wherein The mixed occupation ratio of lithium atoms and nickel atoms in the positive electrode material is 1.2 - 5.

3. The cathode material according to claim 1, wherein The average number of primary particles per square micron of cross-section in secondary particles with a particle diameter of 5 - 15 μm in the positive electrode material is 4 - 25.

4. The cathode material according to claim 1, wherein The positive electrode material satisfies: 25 ≤ A * B ≤ 40.

5. The cathode material according to claim 1, wherein The positive electrode material includes LiNi x M 1-x O2; The M is any one of Co, Mn, and Mg, and 0.7 ≤ x ≤ 0.

98.

6. The cathode material according to claim 5, wherein The positive electrode material is LiNi x M 1-x O2; where 0.9 ≤ x ≤ 0.

98.

7. The cathode material according to claim 6, wherein The positive electrode material is LiNi 0.9 M 0.1 O2; The mixed occupation ratio of lithium atoms and nickel atoms in the positive electrode material is 2.2 - 3.7, and the average number of primary particles per square micron of cross-section in secondary particles with a particle diameter of 5 - 15 μm in the positive electrode material is 5 - 18.

8. The cathode material according to claim 6, wherein The positive electrode material is LiNi 0.95 M 0.05 O2; the mixing occupancy ratio of lithium atoms and nickel atoms in the positive electrode material is 3 to 4.5, and the average number of primary particles per square micron of cross-section in secondary particles with a particle diameter of 5 to 15 μm in the positive electrode material is 4 to 14.

9. The cathode material according to claim 6, characterized in that, The positive electrode material is LiNi 0.98 M 0.02 O2; in the positive electrode material, the mixed occupancy ratio of lithium atoms and nickel atoms is 2 to 3.6, and the average number of primary particles per square micron cross-section in secondary particles with a particle diameter of 5 to 15 μm in the positive electrode material is 9 to 17.

10. The cathode material according to claim 1, characterized in that, The positive electrode material includes LiNi y Co z M' 1-y-z O2; M' is any one of Mn, Mg, and Al, 0.7 ≤ y ≤ 0.98, 0.05 ≤ z ≤ 0.3 and y + z < 1.

11. The cathode material according to claim 10, characterized in that, The positive electrode material is LiNi y Co z M’ 1-y-z O2; where 0.8 ≤ y ≤ 0.

95.

12. The cathode material according to claim 11, wherein, The positive electrode material is LiNi 0.8 Co 0.1 M’ 0.1 O2; the mixing occupancy ratio of lithium atoms and nickel atoms in the positive electrode material is 1.5 to 2.2, and the average number of primary particles per square micron cross-section in secondary particles with a particle diameter of 5 to 15 μm in the positive electrode material is 14 to 24.

13. The cathode material according to claim 11, wherein The positive electrode material is LiNi 0.9 Co 0.05 M’ 0.05 O2; the mixing occupancy ratio of lithium atoms and nickel atoms in the positive electrode material is 1.5 to 2.3, and the average number of primary particles per square micrometer cross-section in secondary particles with a particle diameter of 5 to 15 μm in the positive electrode material is 12 to 22.

14. The cathode material according to claim 11, wherein The positive electrode material is LiNi 0.95 Co 0.025 M’ 0.025 O2; the mixing occupancy ratio of lithium atoms and nickel atoms in the positive electrode material is 2 to 2.6, and the average number of primary particles per square micrometer cross-section in secondary particles with a particle diameter of 5 to 15 μm in the positive electrode material is 12 to 22.

15. The cathode material according to claim 5 or 10, characterized in that, The positive electrode material further includes a doping element, and the doping element is at least one of niobium, tungsten, molybdenum, tantalum, titanium, zirconium, boron, aluminum, and magnesium.

16. The cathode material according to claim 15, wherein The positive electrode material further includes a doping element, and the doping amount of the doping element in the positive electrode material is 0.5 - 5% in terms of molar percentage.

17. The cathode material according to claim 16, characterized in that, The positive electrode material includes LiNi x M 1-x O2 and niobium, where 0.9 ≤ x ≤ 0.

98. The mixing occupancy ratio of lithium atoms and nickel atoms in the positive electrode material is 3 to 4.

5. The average number of primary particles per square micrometer of cross-section in secondary particles with a particle diameter of 5 to 15 μm in the positive electrode material is 6 to 15.

18. The cathode material according to claim 16, wherein The positive electrode material includes LiNi y Co z M’ 1-y-z O2 and niobium, where 0.8 ≤ y ≤ 0.

95. The mixing occupancy ratio of lithium atoms and nickel atoms in the positive electrode material is 1.2 to 3.

5. The average number of primary particles per square micron of cross-section in secondary particles with a particle diameter of 5 to 15 μm in the positive electrode material is 11 to 22.

19. The cathode material according to claim 1, wherein The mass content ratio of particles with a diameter of 5 - 15 μm in the positive electrode material is ≥ 50%.

20. The cathode material according to claim 1, wherein The specific surface area of the positive electrode material is 5 to 15 m 2 / g.

21. A secondary battery, characterized in that, It includes a positive electrode plate, a separator, and a negative electrode plate; the positive electrode plate includes the positive electrode material according to any one of claims 1 - 20.

22. An electrical device, characterized in that, It includes the secondary battery according to claim 21, and the secondary battery serves as the power supply for the electrical device.

23. The electrical device according to claim 22, wherein It includes automobiles, battery cars, boats, and lighting lamps.

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