Multi-element positive electrode material, preparation method and application thereof, positive electrode sheet and lithium ion battery

Abstract

This invention relates to the field of lithium-ion battery technology, specifically to a multi-element cathode material, its preparation method and application, a cathode sheet, and a lithium-ion battery; the multi-element cathode material comprises: cathode material A having the composition shown in Formula I and cathode material B having the composition shown in Formula III, wherein the electron microscopy particle size P of cathode material A is... A50 The electron microscopy particle size P of the cathode material B is 10-18 μm. B50 2-6.5 μm; Li a1 Ni x1 Co y1 Mn z1 M 1 b1 J 1 c1 O2(I), M 1 Satisfy: Li a2 Ni x2 Co y2 Mn z2 M 2 b2 J 2 c2 O2(Ⅲ). The multi-element cathode material provided by this invention has excellent capacity, rate performance and cycle performance; at the same time, the multi-element cathode material has a high compaction relative density, which improves the battery performance of the cathode sheet.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to a multi-element cathode material, its preparation method and application, a cathode sheet containing the multi-element cathode material, and a lithium-ion battery containing the cathode sheet. Background Technology

[0002] With the rapid development of society, economy, and technology, excessive energy consumption has led to energy depletion and increasingly serious environmental pollution. The world is advocating energy conservation and emission reduction. Green and environmentally friendly practices have become the main focus of society today. The automotive industry has now become one of the world's largest energy consumers and polluters. Therefore, solving the problems of energy consumption and environmental pollution should begin with the automotive industry, reducing energy consumption and pollution.

[0003] Electric vehicles have developed rapidly in recent years. Traditional vehicles consume non-renewable energy sources such as petroleum, resulting in energy consumption and environmental pollution. Electricity, on the other hand, can be obtained from renewable energy sources such as nuclear power, hydropower, and wind power without pollution. Therefore, the demand for lithium-ion batteries has increased significantly.

[0004] Lithium-ion battery cathode materials are an integral part of lithium-ion batteries, directly affecting their performance and accounting for a significant proportion. Improving the performance of lithium-ion battery cathode materials can effectively promote the development and use of electric vehicles. Currently, common cathode materials are mainly classified into three types based on particle size: large particles (particle size greater than 10μm), small particles (particle size less than 5μm), and blends of large and small particles. Large particles have good cycle performance but poor rate performance; small particles have good rate performance but poor cycle performance; although blended materials can effectively improve the electrode compaction density, the problems of both large and small particle sizes are not resolved, and the various electrical properties of the cathode material cannot be effectively balanced after blending. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical problems and provide a new multi-element cathode material, its preparation method and application, a cathode sheet containing the multi-element cathode material, and a lithium-ion battery containing the cathode sheet. The multi-element cathode material has excellent capacity, rate performance and cycle performance. At the same time, the multi-element cathode material has a high compaction relative density, thereby improving the battery performance of the cathode sheet.

[0006] To achieve the above objectives, a first aspect of the present invention provides a multi-element cathode material, the multi-element cathode material comprising: cathode material A having the composition shown in Formula I and cathode material B having the composition shown in Formula III, wherein the electron microscopy particle size P of cathode material A is... A50 The electron microscopy particle size P of the cathode material B is 10-18 μm. B50 Its thickness is 2-6.5 μm;

[0007] Li a1 Ni x1 Co y1 Mn z1 M 1 b1 J 1 c1 O2(I), where 0.9≤a1≤1.1, 0.5≤x1<1, 0

[0008] <y1<0.5, 0<z1<0.5, 0<b1≤0.02, 0≤c1≤0.02, and x1+y1+z1=1; M 1 satisfy: R M 1 For M 1 The ionic radius, in nm; R Ni For Ni 3+ The ionic radius is 0.056 nm; C M 1 M in the positive electrode material A 1 Relative to the molar ratio of (Ni+Co+Mn);

[0009] Li a2 Ni x2 Co y2 Mn z2 M 2 b2 J 2 c2 O2(Ⅲ), where 0.9≤a2≤1.1, 0.5≤x2<1,

[0010] 0<y2<0.5, 0<z2<0.5, 0<b2≤0.03, 0≤c2≤0.03, and x2+y2+z2=1; M 2 Selected from those that can form M with O 2 Elements with -O bonds and bond energies ≥ 395 kJ / mol;

[0011] J 1 and J 2 Each element is independently selected from at least one of W, Mo, Zr, Al, V, Ti, B, Co, Nb, La, Y, Ce, and Mg.

[0012] Preferably, c1 in formula I is less than c2 in formula III.

[0013] Preferably, in formula II, the element M 1 ionic radius R M 1 ≥0.058nm, preferably 0.058-0.075nm.

[0014] Preferably, the element M 1 It also satisfies: 0.05≤C M 1 ×R M 1 ×1000≤1(Ⅳ).

[0015] Preferably, the element M 2 satisfy: Where, n Ni 1 The molar ratio of Ni to (Ni+Co+Mn) in the cathode material A; n Ni 2 The molar ratio of Ni to (Ni+Co+Mn) in the cathode material B; C M 2 M in the positive electrode material B 2 The molar ratio relative to (Ni+Co+Mn).

[0016] A second aspect of the present invention provides a method for preparing a multi-element cathode material, the method comprising: mixing cathode material A with the composition shown in Formula I and cathode material B with the composition shown in Formula III to obtain a multi-element cathode material;

[0017] Among them, the electron microscopy particle size P of the positive electrode material A A50 The electron microscopy particle size P of the cathode material B is 10-18 μm. B50 Its thickness is 2-6.5 μm;

[0018] Li a1 Ni x1 Co y1 Mn z1 M 1 b1 J 1 c1 O2(I), where 0.9≤a1≤1.1, 0.5≤x1<1, 0

[0019] <y1<0.5, 0<z1<0.5, 0<b1≤0.02, 0≤c1≤0.02, and x1+y1+z1=1; M 1 satisfy: R M 1 For M 1 The ionic radius, in nm; R Ni For Ni 3+ The ionic radius is 0.056 nm; C M 1 M in the positive electrode material A 1 Relative to the molar ratio of (Ni+Co+Mn);

[0020] Li a2 Ni x2 Co y2 Mn z2 M 2 b2 J 2 c2 O2(Ⅲ), where 0.9≤a2≤1.1, 0.5≤x2<1,

[0021] 0<y2<0.5, 0<z2<0.5, 0<b2≤0.03, 0≤c2≤0.03, and x2+y2+z2=1; M 2 Selected from those that can form M with O 2 Elements with -O bonds and bond energies ≥ 395 kJ / mol;

[0022] J 1 and J 2 Each element is independently selected from at least one of W, Mo, Zr, Al, V, Ti, B, Co, Nb, La, Y, Ce, and Mg.

[0023] Preferably, the mass ratio of the positive electrode material A to the positive electrode material B is 6-9:4-1, and more preferably (lg P) A50 )-P A50 :(lg P B50 )-P B50 .

[0024] The third aspect of this invention provides a multi-element cathode material provided in the first aspect, or the application of a multi-element cathode material prepared by the preparation method provided in the third aspect in a lithium-ion battery.

[0025] A fourth aspect of the present invention provides a positive electrode sheet, the positive electrode sheet comprising: a positive current collector and a positive additional layer disposed on at least one surface of the positive current collector;

[0026] The positive electrode additional layer is composed of a binder and a multi-element positive electrode material provided in the first aspect, or a multi-element positive electrode material prepared by the preparation method provided in the third aspect.

[0027] The fifth aspect of the present invention provides a lithium-ion battery, the lithium-ion battery comprising the positive electrode sheet provided in the fourth aspect.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] (1) The multi-element cathode material provided by this invention not only includes large-particle cathode material A and small-particle cathode material B, but also further performs M-processing on cathode material A and cathode material B respectively. 1 and M 2Element doping improves the rate performance of cathode material A and the cycle performance of cathode material B, respectively, resulting in multi-element cathode materials with excellent capacity, rate performance, and cycle performance; especially by controlling M 1 and M 2 The type and amount of element doping can further regulate the performance of multi-element cathode materials;

[0030] (2) The multi-element cathode material provided by the present invention uses large-particle cathode material A to build the framework and small-particle cathode material B to fill the gaps, thereby improving the compaction relative density of the multi-element cathode material, which is beneficial to battery preparation; in particular, by controlling the mass ratio of cathode material A and cathode material B with electron microscope particle size difference in the multi-element cathode material, the compaction relative density ≥70% can improve the volumetric energy density of the battery and achieve the optimal battery level;

[0031] (3) The preparation method provided by the present invention is simple and pollution-free, the introduction of dopant elements is simple and the process is controllable, making it suitable for industrial production. Attached Figure Description

[0032] Figure 1 Here is a SEM image of the multi-element cathode material P1 prepared in Example 1;

[0033] Figure 2 The graphs show the cycling performance of the multi-element cathode materials prepared in Example 1 and Comparative Example 1 at a 1C rate, where the test temperature is 45°C and the voltage range is 3.0-4.3V. Detailed Implementation

[0034] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0035] In this invention, unless otherwise specified, the terms "first," "second," "third," and "fourth" do not indicate a sequential order, nor do they limit the specific materials or steps; they are merely used to distinguish or indicate that these are not the same material or step. For example, "first" and "second" in "first nickel salt" and "second nickel salt" are only used to indicate that these are not the same nickel salt; similarly, "first," "second," "third," and "fourth" in "first sintering," "second sintering," "third sintering," and "fourth sintering" are only used to indicate that these are not the same sintering process.

[0036] The first aspect of this invention provides a multi-element cathode material, the multi-element cathode material comprising: cathode material A having the composition shown in Formula I and cathode material B having the composition shown in Formula III, wherein the electron microscopy particle size P of cathode material A is... A50 The electron microscopy particle size P of the cathode material B is 10-18 μm. B50 Its thickness is 2-6.5 μm;

[0037] Li a1 Ni x1 Co y1 Mn z1 M 1 b1 J 1 c1 O2(I), where 0.9≤a1≤1.1, 0.5≤x1<1, 0

[0038] <y1<0.5, 0<z1<0.5, 0<b1≤0.02, 0≤c1≤0.02, and x1+y1+z1=1; M 1 satisfy: R M 1 For M 1 The ionic radius, in nm; R Ni For Ni 3+ The ionic radius is 0.056 nm; C M 1 M in the positive electrode material A 1 Relative to the molar ratio of (Ni+Co+Mn);

[0039] Li a2 Ni x2 Co y2 Mn z2 M 2 b2 J 2 c2 O2(Ⅲ), where 0.9≤a2≤1.1, 0.5≤x2<1,

[0040] 0<y2<0.5, 0<z2<0.5, 0<b2≤0.03, 0≤c2≤0.03, and x2+y2+z2=1; M 2 Selected from those that can form M with O 2 Elements with -O bonds and bond energies ≥ 395 kJ / mol;

[0041] J 1 and J 2 Each element is independently selected from at least one of W, Mo, Zr, Al, V, Ti, B, Co, Nb, La, Y, Ce, and Mg.

[0042] The inventors of this invention discovered that both large-particle and small-particle cathode materials have their own drawbacks. Large-particle cathode materials have good cycle performance but poor rate performance, while small-particle cathode materials have good rate performance but poor cycle performance. If the capacity, rate, and cycle performance of the two blended cathode materials differ significantly, the electrical performance will be poor, and the capacity, rate, and cycle performance will be close to that of the worse of the two materials. Therefore, this invention prioritizes improving the performance of large-particle cathode material A and small-particle cathode material B, making their electrical properties similar. This allows for increased compaction density and electrode loading rate while maintaining electrical performance, thereby improving battery performance.

[0043] Specifically, element M is doped into cathode material A. 1 By regulating M 1 ionic radius R M 1 >Ni 3+ ionic radius R Ni (0.056nm), and ensure the doping of M 1 Ionic radius and mixing amount C M 1 Satisfy Equation II so that M 1 The optimal doping was achieved in cathode material A, while selecting a suitable M 1 The ionic radius of M makes 1 Increasing the interlayer spacing by extending into the metal layer enhances lithium-ion transport efficiency, which can further improve rate performance, especially by further limiting the primary particle size D of the cathode material A. PSx Smaller size shortens the lithium-ion transport path, effectively improving rate performance; doping element M in cathode material B 2 By regulating M 2 Forming M with O 2 -O bonds with bond energies ≥395kJ / mol improve the stability of the material's bulk structure; high-doped M 2 It can more effectively stabilize the material structure, prevent electrolyte corrosion from damaging the material structure, and further improve cycle performance.

[0044] Meanwhile, this invention also effectively improves the compaction relative density of the multi-element cathode material by controlling the electron microscopic particle size of cathode material A and cathode material B, as well as their mass ratio, especially by controlling the compaction relative density λ≥70%, thereby achieving the optimal level of the battery while facilitating battery fabrication.

[0045] In this invention, unless otherwise specified, the electron microscopy particle size parameter (P) A50 P B50 P MA50 P MB50The secondary particle diameter was obtained by randomly selecting 200 particles under an electron microscope and statistically analyzing them; the electron microscope particle size parameter (D) was obtained. PSx The diameter of 200 positive electrode material A particles were randomly selected under an electron microscope and counted once.

[0046] In this invention, unless otherwise specified, the doping content (C) M 1 C M 2 The results were obtained through cross-sectional electron probe microanalysis. Fifty particles were selected from cathode material A and cathode material B respectively for electron probe surface scanning tests, and the average value was obtained. Specifically, the test range for cathode material A was the interior of the material at a distance greater than 1 μm from the surface, and the test range for cathode material B was the interior of the material at a distance greater than 0.5 μm from the surface. If there was dopant enrichment in the interior or at the grain boundary, it was deducted, and only the uniformly doped part was taken.

[0047] In this invention, in formula II, based on (R) M 1 -R Ni Since M > 0, we know that M 1 ionic radius R M 1 Greater than Ni(Ni 3+ =0.056nm), Co(Co) 3+ =0.0545nm), Mn(Mn 4+ =0.053nm), therefore, element M is doped in cathode material A. 1 This allows lithium ions to enter the crystal lattice, thereby increasing the interlayer spacing and making it easier for lithium ions to insert and extract, effectively improving the rate performance of cathode material A; while if M 1 The larger the ionic radius, the more difficult it is to uniformly dope in the crystal lattice. In this invention, satisfying Equation II describes the M-type doping of large-particle lattice in multi-element cathode materials. 1 More of these can increase the multiplier.

[0048] Meanwhile, in cathode material B, the bonding forces between the main elements Ni and Co and O are generally weak. For example, the bond energy of the Ni-O bond is 391 kJ / mol, the Co-O bond energy is 368 kJ / mol, and the Mn-O bond energy is 402 kJ / mol. Therefore, during battery cycling, unmodified cathode material B, especially cathode material B with good rate performance, is prone to structural phase transitions, releasing lattice O. Once O release occurs, this process is irreversible, which affects the cycling performance of the multi-element cathode material. Therefore, in order to stabilize the lattice O of cathode material B and prevent the release of lattice O, this invention uses Mn doping... 2 Metallic elements M with -O bonds and bond energies ≥395 kJ / mol 2(The lowest bond energy is greater than Ni-O and Co-O, and second only to Mn-O, which is used to increase structural stability among the main elements.) Introducing elements with strong bonding with O stabilizes the O atom, thereby improving structural stability and enhancing cycle and safety performance.

[0049] In summary, this invention reduces the difference in electrochemical performance between different materials in the blend by limiting the difference in electron microscopy particle size between cathode material A and cathode material B, and selectively doping cathode material A and cathode material B. This avoids the "weakest link" effect and achieves convergent electrochemical performance even with significant particle size differences. Consequently, it simultaneously improves the capacity, rate capability, cycle performance, and compaction density of the blend, further increasing the loading rate of the cathode electrode and enhancing battery performance.

[0050] In this invention, unless otherwise specified, in Formulas I and III, a1 and a2 may be the same or different; x1 and x2 may be the same or different; y1 and y2 may be the same or different; z1 and z2 may be the same or different.

[0051] In this invention, unless otherwise specified, in formula II, C M 1 The results were obtained through cross-sectional electron probe microanalysis. In the cathode material A, the same amount of dopant element M was added in different ways. 1 Although M in the composition formula I of cathode material A 1 The subscript b1 (amount added) is the same, but C M 1 The different values ​​of (doping amount) are mainly due to the presence of some doping elements M. 1 Residual material, C, remains at the grain boundaries or surface of cathode material A. In other words, C M 1 ≤b1.

[0052] In some embodiments of the present invention, the electron microscopy particle size P of the positive electrode material A is... A50 The particle size is 10-18 μm, for example, 10 μm, 11 μm, 13 μm, 15 μm, 17 μm, 18 μm, or any value within the range of any two values, preferably 11-17 μm; the electron microscopy particle size P of the positive electrode material B is... B50 The micrometer value is 2-6.5 μm, for example, 2 μm, 2.5 μm, 3.5 μm, 4 μm, 4.5 μm, 6.5 μm, or any value within the range of any two values, preferably 2.5-4.5 μm. Satisfying the above range is more conducive to improving the capacity, rate performance, and cycle performance of the multi-element cathode material.

[0053] In this invention, generally speaking, the P of the positive electrode material A is...A50 ≠D A50 P of cathode material B B50 ≠D B50 In the preferred case, the P of the cathode material A A50 =D A50 P of cathode material B B50 =D B50 Based on the definition of equivalent particle size: when a particle has a physical property (such as volume, weight, settling velocity, etc.) that is the same as or similar to that of a homogeneous spherical particle, we use the diameter of the spherical particle to represent the diameter of the non-spherical particle. The particle size measured by the laser method is the equivalent volume diameter, that is, the diameter of a homogeneous spherical particle with the same volume as the measured particle, corresponding to the D of this invention. A50 / D B50 The particle size measured by the microscopic imaging method is the equivalent projected area diameter, that is, the diameter of a spherical particle with the same projected area as the measured particle, corresponding to P in this invention. A50 / P B50 The two detection mechanisms are different, which is reflected in the deviation of the data measured in this invention.

[0054] In some embodiments of the present invention, preferably, in formula I, 0.9≤a1≤1.05, 0.7≤x1<1, 0.03≤y1≤0.3, 0.01≤z1≤0.25, 0.001≤b1≤0.015, 0.001≤c1≤0.015, and x1+y1+z1=1; more preferably, in formula I, 1.01≤a1≤1.05, 0.8≤x1≤0.95, 0.05≤y1≤0.2, 0.02≤z1≤0.2, and x1+y1+z1=1.

[0055] In some embodiments of the present invention, preferably, in formula I, the element M 1 At least one element selected from Mg, Nb, W, La, Ce, Zr, Y, and Ti; more preferably, the element M 1 At least one element selected from Mg, Nb, W, Zr, and Ti. The doping element M satisfies the above requirements. 1 By effectively increasing the interlayer spacing, the rate performance of cathode material A can be improved.

[0056] In this invention, Mg(Mg) 2+ =0.072nm), Nb(Nb 5+ =0.064nm), W(W 6+ =0.06nm), La (La 3+ =0.1032nm), Ce(Ce 4+ =0.087nm), Zr(Zr 4+=0.072nm), Y(Y 3+ =0.09nm), Ti(Ti 4+ =0.0605nm).

[0057] In some embodiments of the present invention, preferably, in formula III, 0.9≤a2≤1.05, 0.7≤x2<1, 0.02≤y2≤0.25, 0.01≤z2≤0.3, and x2+y2+z2=1, 0.001≤b2≤0.03, 0.001≤c2≤0.02; more preferably, in formula III, 1.01≤a2≤1.05, 0.8≤x2≤0.95, 0.05≤y2≤0.2, 0.05≤z2≤0.2, and x2+y2+z2=1, 0.002≤b2≤0.02.

[0058] In some embodiments of the present invention, preferably, in formula III, the element M 2 At least one element selected from Al, V, Si, La, Y, Ti, and Zr. The doping element M satisfies the above requirements. 2 It can interact strongly with oxygen ions to maintain relative structural stability. Compared with the main elements (Ni, Co, Mn), it is easier to enhance structural stability, thus giving the cathode material B better cycle performance.

[0059] In this invention, when M 1 With M 2 When each element is independently selected from the same element, such as Zr, Ti, Y, etc., the inventors, through numerous creative studies, discovered that, taking Zr as an example, when Zr is selected in a limited amount of C... M 1 When Zr is doped into cathode material A, it contributes more to increasing the interlayer spacing, thereby improving the rate performance of cathode material A. When Zr is doped into cathode material B, it contributes more to increasing the bond energy between Zr and O, thereby improving the cycle performance of cathode material B. When cathode material A and cathode material B are mixed to form a multi-element cathode material, the electrical properties of the two can be effectively balanced, thereby improving the capacity, rate performance and cycle performance of the multi-element cathode material.

[0060] In some embodiments of the present invention, more preferably, in Formula III, the element M 2 The doping element M is selected from Al and non-Al elements, and the non-Al elements are selected from at least one element selected from V, Si, La, Y, Ti, and Zr. The doping element M satisfies the above requirements. 2 This is more conducive to improving the cycle performance of cathode material B.

[0061] In some embodiments of the present invention, preferably, c1 in Formula I < c2 in Formula III. That is, more coating agent (J) is coated onto the cathode material B with a larger specific surface area. 2 This can achieve the same coating effect as cathode material A, further balancing the differences in electrical performance between the two; at the same time, since cathode material B is made of small particles and has poor cycling performance, a larger dose of coating agent can further improve the cycling performance of the blended material.

[0062] In this invention, unless otherwise specified, the surface coating element (J) 1 J 2 It can be tested using a surface electron probe.

[0063] In some embodiments of the present invention, preferably, in formula II, the element M 1 ionic radius R M 1 ≥0.058 nm, for example, 0.058 nm, 0.06 nm, 0.064 nm, 0.07 nm, 0.075 nm, 0.09 nm, 0.1 nm, 0.15 nm, and any value within the range of any two values, more preferably 0.058-0.075 nm. The doping element M satisfies the above-defined requirements. 1 This allows cathode material A to possess both excellent capacity and rate performance.

[0064] In some embodiments of the present invention, preferably, the element M 1 It also satisfies: 0.05≤C M 1 ×R M 1 ×1000≤1(Ⅳ). In this invention, in formula Ⅳ, C M 1 ×R M 1 The larger the value of element M, the better the capacity of cathode material A. However, excessively large values ​​will reduce the capacity of cathode material A. Therefore, when the element M... 1 When Equation IV is satisfied, the rate capability and capacity of cathode material A can be balanced.

[0065] In some embodiments of the present invention, preferably, the element M 2 satisfy: Where, n Ni 1 The molar ratio of Ni to (Ni+Co+Mn) in the cathode material A; n Ni 2 The molar ratio of Ni to (Ni+Co+Mn) in the cathode material B; C M 2M in the positive electrode material B 2 The molar ratio relative to (Ni+Co+Mn).

[0066] In this invention, unless otherwise specified, in formula V, n Ni 1 x1 is the subscript of Ni in the cathode material A composed of formula I; n Ni 2 x2 is the subscript of Ni in the cathode material B composed of formula III.

[0067] In this invention, unless otherwise specified, in formula V, C M 2 The results were obtained through cross-sectional electron probe microanalysis. In the cathode material B, the same amount of dopant element M was added in different ways. 2 Although M in formula III of cathode material B 2 The subscript b2 (amount added) is the same, but C M 2 The different values ​​of (doping amount) are mainly due to the presence of some doping elements M. 2 Residual material C remains at the grain boundaries or surface of cathode material B. M 2 ≤b2.

[0068] In this invention, when the doping element M 2 For specific doping elements, and C M 2 The optimal doping amount of cathode material B satisfies the V range and can achieve the effect of stabilizing the small particle structure.

[0069] In some embodiments of the present invention, preferably, the grain size D of the multi-element cathode material obtained by XRD testing is... XRD Satisfaction VI:

[0070] 1550×D PSx ×W A +750×(1-W A )≤D XRD ≤1750×D PSx ×W A +850×(1-W A ) (VI),

[0071] Among them, D PSx W represents the primary particle size of the cathode material A, in μm. A It represents the mass percentage of cathode material A in the multi-element cathode material.

[0072] In this invention, when the grain size D of the multi-element cathode material... XRDWhen equation VI above is satisfied, the primary particle size D of the cathode material A is... PSx Suitable, with good rate-cycle performance. If D... XRD If the size is too large, it indicates that the primary particle size D of the cathode material A is too large. PSx Smaller, poorer cycle; if D XRD If the size is too small, it indicates that the primary particle size D of the cathode material A is too small. PSx Larger values ​​result in a worse magnification.

[0073] In some embodiments of the present invention, preferably, the grain size D of the multi-element cathode material is... XRD for Preferred Grain size D that meets the above range XRD This indicates that the mixing ratio of cathode material A and cathode material B is appropriate. If D XRD If D is too large, it indicates that there is too much positive electrode material B. XRD If it is too small, it means that there is too much positive electrode material A.

[0074] In some embodiments of the present invention, preferably, the primary particle size D of the positive electrode material A is... PSx The primary particle size D is 0.2-0.5 μm. PSx This indicates that the multi-element cathode material has excellent cycle performance and rate performance.

[0075] In some embodiments of the present invention, preferably, in the multi-element cathode material, the mass ratio of cathode material A to cathode material B is 6-9:4-1, for example, 6:4, 7:3, 8:2, 9:1, and any value within the range of any two values, preferably (lg P A50 )-P A50 :(lg P B50 )-P B50 For example, (lg P) A50 ):(lg P B50 ), P A50 :P B50 Meeting the above-mentioned mass ratio limits is more conducive to increasing the compaction density of the multi-element cathode material, thereby improving its volumetric energy density.

[0076] In some embodiments of the present invention, preferably, the compacted relative density λ of the multi-element cathode material is ≥70%, more preferably ≥74%, where λ=ρ P / ρ S , ρ P The density of the multi-element cathode material under a pressure of 20 kN is expressed in g / cm³. 3 ;ρ S The true density of the multi-element cathode material is expressed in g / cm³.3 A smaller λ results in lower compaction density, making electrode fabrication more prone to unevenness and lower volumetric energy density.

[0077] A second aspect of the present invention provides a method for preparing a multi-element cathode material, the method comprising: mixing cathode material A with the composition shown in Formula I and cathode material B with the composition shown in Formula III to obtain a multi-element cathode material;

[0078] Among them, the electron microscopy particle size P of the positive electrode material A A50 The electron microscopy particle size P of the cathode material B is 10-18 μm. B50 Its thickness is 2-6.5 μm;

[0079] Li a1 Ni x1 Co y1 Mn z1 M 1 b1 J 1 c1 O2(I), where 0.9≤a1≤1.1, 0.5≤x1<1, 0

[0080] <y1<0.5, 0<z1<0.5, 0<b1≤0.02, 0≤c1≤0.02, and x1+y1+z1=1; M 1 satisfy: R M 1 For M 1 The ionic radius, in nm; R Ni For Ni 3+ The ionic radius is 0.056 nm; C M 1 M in the positive electrode material A 1 Relative to the molar ratio of (Ni+Co+Mn);

[0081] Li a2 Ni x2 Co y2 Mn z2 M 2 b2 J 2 c2 O2(Ⅲ), where 0.9≤a2≤1.1, 0.5≤x2<1,

[0082] 0<y2<0.5, 0<z2<0.5, 0<b2≤0.03, 0≤c2≤0.03, and x2+y2+z2=1; M 2 Selected from those that can form M with O 2 Elements with -O bonds and bond energies ≥ 395 kJ / mol;

[0083] J 1 and J 2 Each element is independently selected from at least one of W, Mo, Zr, Al, V, Ti, B, Co, Nb, La, Y, Ce, and Mg.

[0084] In this invention, the limitations of the positive electrode material A and the positive electrode material B are as described above, and will not be repeated here.

[0085] In some embodiments of the present invention, preferably, the mass ratio of the positive electrode material A to the positive electrode material B is 6-9:4-1, for example, 6:4, 7:3, 8:2, 9:1, and any value within the range of any two values, preferably (lgP) A50 )-P A50 :(lg P B50 )-P B50 For example, (lg P) A50 ):(lg P B50 ), (lg P A50 ):P B50 P A50 :(lg P B50 ), P A50 :P B50 Meeting the above-mentioned mass ratio limits is more conducive to increasing the compaction density of the multi-element cathode material, thereby improving its volumetric energy density.

[0086] In some embodiments of the present invention, preferably, the mixing conditions include: a temperature of 20-60°C and a time of 0.5-10h.

[0087] In this invention, the source of the positive electrode material A has a wide range of choices; it can be obtained by purchasing or by self-production. Preferably, the preparation method further includes: obtaining the positive electrode material A through the following steps:

[0088] (I-1) In the presence of a first solvent, the components in component C are mixed and subjected to a first coprecipitation reaction to obtain a precursor of material A, wherein component C contains a first nickel salt, a first cobalt salt, a first manganese salt, a first precipitant and a first complexing agent;

[0089] (I-2) The precursor of material A is mixed with each component in component D and subjected to a first sintering to obtain an intermediate of material A, wherein component D contains a first lithium salt;

[0090] (I-3) The intermediate material A and an optional first coating agent are mixed and subjected to a second sintering to obtain a second sintered product, wherein the first coating agent contains the element J. 1 ;

[0091] Component C and / or component D further contain a first dopant, wherein the first dopant contains element M. 1 ;

[0092] The intermediate material A or the second sintered product is used as the positive electrode material A.

[0093] In this invention, in formula (I), when c1 = 0, the intermediate material A obtained in step (I-2) is directly used as the positive electrode material A; when c1 ≠ 0, step (I-3) is performed, and the second sintered product obtained is used as the positive electrode material A.

[0094] In some embodiments of the present invention, preferably, in step (I-1), the first solvent includes, but is not limited to, water; the first nickel salt is selected from at least one of nickel sulfate, nickel chlorate, nickel nitrate, and nickel acetate; the first cobalt salt is selected from at least one of cobalt sulfate, cobalt chlorate, cobalt nitrate, and cobalt acetate; the first manganese salt is selected from at least one of manganese sulfate, manganese chlorate, manganese nitrate, and manganese acetate; the first precipitant is selected from sodium hydroxide and / or potassium hydroxide; and the first complexing agent is selected from at least one of ammonia, disodium ethylenediaminetetraacetate, ammonium nitrate, ammonium chloride, and ammonium sulfate.

[0095] In some embodiments of the present invention, preferably, the amounts of the first nickel salt, the first cobalt salt, and the first manganese salt satisfy the following: n(Ni1):n(Co1):n(Mn1), wherein 0.5≤n(Ni1)<1, 0<n(Co1)<0.5, 0<n(Mn1)<0.5; more preferably, 0.7≤n(Ni1)<1, 0.03≤n(Co1)≤0.3, 0.01≤n(Mn1)≤0.25; more preferably, 0.8≤n(Ni1)≤0.95, 0.05≤n(Co1)≤0.2, 0.02≤n(Mn1)≤0.2.

[0096] In some embodiments of the present invention, preferably, the conditions for the first coprecipitation reaction include: a temperature of 40-80°C, a time of 5-40 h, a rotation speed of 40-80 rpm, and a pH value of 10-12.5. In the present invention, using a smaller rotation speed and a smaller pH value is more conducive to obtaining a precursor material A with a small BET and a dense particle structure, and is also conducive to obtaining a cathode material A of a specific size.

[0097] In some embodiments of the present invention, preferably, the electron microscopy particle size P of the precursor of material A is... MA50 The thickness is 10-18 μm, and the BET thickness is 4-15 μm. 2 / g.

[0098] In some embodiments of the present invention, preferably, in step (I-2), the first lithium salt is selected from at least one of lithium carbonate, lithium hydroxide, lithium oxide and lithium acetate.

[0099] In some embodiments of the present invention, preferably, the amount of the first lithium salt satisfies: 0.9≤[n(Li1)] / [n(Ni1)+n(Co1)+n(Mn1)]≤1.1; more preferably, the amount of the first lithium salt satisfies: 0.9≤[n(Li1)] / [n(Ni1)+n(Co1)+n(Mn1)]≤1.05; more preferably, the amount of the first lithium salt satisfies: 1.01≤[n(Li1)] / [n(Ni1)+n(Co1)+n(Mn1)]≤1.05.

[0100] In this invention, unless otherwise specified, the presence of a first dopant in component C and / or component D means that the first dopant can be in component C, component D, or even simultaneously in both components C and D.

[0101] In some embodiments of the present invention, preferably, component C contains at least a portion of the first dopant. That is, component C may contain all or part of the first dopant. This arrangement avoids the presence of dopant elements M with excessively large ionic radii. 1 Unable to effectively dope into the metal layer, thus increasing the dopant element M 1 doping amount C M 1 This also helps to obtain a cathode material A with more uniform doping.

[0102] In this invention, when conditions permit, it is preferable to use dopant element M. 1 Added during the preparation of precursor material A, even if component C contains all of the first dopant, it can allow the dopant element M with a larger ionic radius to be added. 1 Completely doped in, without appearing at grain boundaries or surfaces, avoiding element M 1 The electrical performance of cathode material A is affected because the ionic radius is too large to be doped.

[0103] In some embodiments of the present invention, preferably, the element M 1 ionic radius R M 1 ≥0.058μm, more preferably 0.058-0.075μm.

[0104] In some embodiments of the present invention, preferably, the first dopant is selected from those containing element M. 1At least one of oxides, fluorides, carbonates, hydroxides and acetates, preferably selected from at least one of oxides, fluorides, carbonates, hydroxides, oxalates and acetates containing Mg, Nb, W, La, Ce, Zr, Y and Ti, more preferably selected from at least one of oxides, fluorides, carbonates, hydroxides, oxalates and acetates containing Mg, Nb, W, Zr and Ti.

[0105] In some specific embodiments of the present invention, when the first dopant is added in step (I-1), that is, added to the precursor of material A, the first dopant is preferably selected from those containing M. 1 A soluble salt; when the first dopant is added in step (I-2), that is, when intermediate material A is added, the first dopant is preferably selected from those containing M. 1 Oxides.

[0106] In some embodiments of the present invention, preferably, the amount of the first dopant satisfies: 0 < [n(M 1 )] / [n(Ni1)+n(Co1)+n(Mn1)]≤0.02; More preferably, the amount of the first dopant satisfies: 0.001≤[n(Mn1) / [n(Ni1)+n(Co1)+n(Mn1)]≤0.02; 1 )] / [n(Ni1)+n(Co1)+n(Mn1)]≤0.015.

[0107] In some embodiments of the present invention, preferably, in step (I-2), the temperature T1 of the first sintering satisfies equation VII:

[0108]

[0109] Where, n Ni 1 The molar ratio of the first nickel salt in the mixture of the first nickel salt, the first cobalt salt, and the first manganese salt, calculated by metal element; n Mn 1 P represents the molar ratio of the first manganese salt in the mixture of the first nickel salt, the first cobalt salt, and the first manganese salt, calculated by metal element. MA50 The electron microscopic particle size of the precursor material A is denoted as μm.

[0110] In this invention, unless otherwise specified, in equation VII, n Ni 1 x1 is the subscript of Ni in the cathode material A composed of formula I; n Mn 1 z1 is the subscript of Mn in the cathode material A composed of formula I.

[0111] In some embodiments of the present invention, more preferably, the conditions for the first sintering include: being carried out in an oxygen-containing atmosphere at a temperature of 600-1200°C for 10-30 hours. In the present invention, the oxygen-containing atmosphere includes, but is not limited to, an oxygen atmosphere or an air atmosphere.

[0112] In this invention, when the temperature of the first sintering meets the specified range, a cathode material A with small primary particles and large secondary particles can be obtained, thereby improving the rate performance of cathode material A.

[0113] In some embodiments of the present invention, preferably, in step (I-3), the first coating agent is selected from those containing element J. 1 At least one of carbonates, phosphates, fluorides, hydroxides, oxides, and acetates, preferably selected from at least one of carbonates, phosphates, fluorides, hydroxides, oxides, and acetates containing W, Mo, Zr, Al, V, Ti, B, Co, Nb, La, Y, Ce, and Mg.

[0114] In some embodiments of the present invention, preferably, the amount of the first coating agent satisfies: 0 ≤ [n(J 1 )] / [n(Ni1)+n(Co1)+n(Mn1)]≤0.02; More preferably, the amount of the first coating agent satisfies: 0.001≤[n(J) / [n(Ni1)+n(Co1)+n(Mn1)]≤0.02; 1 )] / [n(Ni1)+n(Co1)+n(Mn1)]≤0.015.

[0115] In some embodiments of the present invention, preferably, in step (I-3), the conditions for the second sintering include: being carried out in an oxygen-containing atmosphere at a temperature of 200-1000°C for 5-20 hours. In the present invention, the oxygen-containing atmosphere includes, but is not limited to, an oxygen atmosphere, an air atmosphere, etc.

[0116] In this invention, the source of the positive electrode material B has a wide range of options; it can be obtained by purchasing or by self-production. Preferably, the preparation method further includes: obtaining the positive electrode material B through the following steps:

[0117] (II-1) In the presence of a second solvent, the components in component E are mixed and subjected to a second coprecipitation reaction to obtain a precursor of material B, wherein component E contains a second nickel salt, a second cobalt salt, a second manganese salt, a second precipitant, and a second complexing agent.

[0118] (II-2) The precursor of material B is mixed with each component in component F and subjected to a third sintering to obtain intermediate material B, wherein component F contains a second lithium salt;

[0119] (II-3) The intermediate material B is mixed with an optional second coating agent and subjected to a fourth sintering to obtain a fourth sintered product, wherein the second coating agent contains the element J. 2 ;

[0120] The component E and / or the component F further contain a second dopant, the second dopant containing the element M. 2 ;

[0121] The intermediate material B or the fourth sintering product is used as the positive electrode material B.

[0122] In this invention, in formula (II), when c2 = 0, the intermediate material B obtained in step (II-2) is directly used as the positive electrode material B; when c2 ≠ 0, step (II-3) is performed, and the fourth sintered product obtained is used as the positive electrode material B.

[0123] In some embodiments of the present invention, preferably, in step (II-1), the second solvent includes, but is not limited to, water; the second nickel salt is selected from at least one of nickel sulfate, nickel chlorate, nickel nitrate, and nickel acetate; the second cobalt salt is selected from at least one of cobalt sulfate, cobalt chlorate, cobalt nitrate, and cobalt acetate; the second manganese salt is selected from at least one of manganese sulfate, manganese chlorate, manganese nitrate, and manganese acetate; the second precipitant is selected from sodium hydroxide and / or potassium hydroxide; and the second complexing agent is selected from at least one of ammonia, disodium ethylenediaminetetraacetate, ammonium nitrate, ammonium chloride, and ammonium sulfate.

[0124] In some embodiments of the present invention, preferably, the amounts of the second nickel salt, the second cobalt salt, and the second manganese salt satisfy the following: n(Ni2):n(Co2):n(Mn2), wherein 0.5≤n(Ni2)<1, 0<n(Co2)<0.5, 0<n(Mn2)<0.5; more preferably, 0.7≤n(Ni2)<1, 0.02≤n(Co2)≤0.25, 0.01≤n(Mn2)≤0.3; more preferably, 0.8≤n(Ni2)≤0.95, 0.05≤n(Co2)≤0.2, 0.05≤n(Mn2)≤0.2.

[0125] In some embodiments of the present invention, preferably, the rotation speed of the second precipitation reaction is greater than that of the first precipitation reaction, and the pH value of the second precipitation reaction is greater than that of the first precipitation reaction. Meeting the above limitations results in a material B precursor with a large BET, a loose structure, good sintering activity, and easy shrinkage to form dense small particles during subsequent sintering.

[0126] In some embodiments of the present invention, preferably, the conditions for the second coprecipitation reaction include: a temperature of 40-80°C, a time of 5-40 hours, a rotation speed of 50-90 rpm, and a pH value of 10.5-13. Meeting the above-defined conditions yields a product with specific P... MB50 The precursor material B for BET.

[0127] In some embodiments of the present invention, preferably, the electron microscopy particle size P of the precursor of material B is... MB50 The range is 2-6.5 μm, and the BET range is 10-30 μm. 2 / g.

[0128] In some embodiments of the present invention, preferably, in step (II-2), the second lithium salt is selected from at least one of lithium carbonate, lithium hydroxide, lithium oxide and lithium acetate.

[0129] In some embodiments of the present invention, preferably, the amount of the second lithium salt satisfies: 0.9≤[n(Li2)] / [n(Ni2)+n(Co2)+n(Mn2)]≤1.1; more preferably, the amount of the second lithium salt satisfies: 0.9≤[n(Li2)] / [n(Ni2)+n(Co2)+n(Mn2)]≤1.05; more preferably, the amount of the second lithium salt satisfies: 1.01≤[n(Li2)] / [n(Ni2)+n(Co2)+n(Mn2)]≤1.05.

[0130] In this invention, unless otherwise specified, the presence of a second dopant in component E and / or component F means that the second dopant can be in component E, component F, or even simultaneously in both components E and F.

[0131] In some embodiments of the present invention, preferably, component E contains at least a portion of the second dopant. That is, component E may contain all or part of the second dopant. This configuration is advantageous for obtaining a cathode material B with more uniform doping.

[0132] In this invention, when conditions permit, it is preferable to use dopant element M. 2 Added during the preparation of precursor material B, even if component E contains all of the second dopant, thus enabling M to... 2 Dopant element M with -O bond and bond energy ≥ 395 kJ / mol 2 Completely doped in, without appearing at grain boundaries or surfaces, avoiding element M 2 The electrical properties of cathode material B are affected because it cannot be doped in.

[0133] In some embodiments of the present invention, preferably, the second dopant is selected from those containing element M. 2 It is selected from at least one of oxides, fluorides, carbonates, hydroxides and acetates containing Al, V, Si, La, Y, Ti, Zr, more preferably from at least one of oxides, fluorides, carbonates, hydroxides and acetates containing Al and non-Al elements, wherein the non-Al elements are selected from at least one of V, Si, La, Y, Ti, Zr.

[0134] In some specific embodiments of the present invention, when the second dopant is added in step (II-1), that is, added to the precursor of material B, the second dopant is preferably selected from those containing M. 2 A soluble salt; when the second dopant is added in step (II-2), i.e., when the intermediate for preparing material B is added, the second dopant is preferably selected from those containing M. 2 Oxides.

[0135] In this invention, when the second dopant is selected from at least one of oxides, fluorides, carbonates, hydroxides and acetates containing Al and non-Al elements, the molar ratio of Al and non-Al elements is not limited based on the metal element.

[0136] In some embodiments of the present invention, preferably, the amount of the second dopant satisfies: 0 < [n(M 2 The ratio of the second dopant to the content of the dopant is 0.001 ≤ [n(Ni2) + n(Co2) + n(Mn2)] ≤ 0.03; more preferably, the amount of the second dopant satisfies: 0.001 ≤ [n(Mn2) + n(Co2) + n(Mn2)] ≤ 0.03; 2 The content of the second dopant is less than or equal to 0.03; more preferably, the amount of the second dopant satisfies: 0.002 ≤ [n(Ni2) + n(Co2) + n(Mn2)] / [n(Ni2) + n(Co2) + n(Mn2)] ≤ 0.03; 2 )] / [n(Ni2)+n(Co2)+n(Mn2)]≤0.02.

[0137] In some embodiments of the present invention, preferably, the conditions for the third sintering include: being carried out in an oxygen-containing atmosphere at a temperature of 600-1200°C for 10-30 hours. In the present invention, the oxygen-containing atmosphere includes, but is not limited to, an oxygen atmosphere or an air atmosphere.

[0138] In some embodiments of the present invention, preferably, in step (II-3), the second coating agent is selected from those containing element J. 2At least one of carbonates, phosphates, fluorides, hydroxides, oxides, and acetates, preferably selected from at least one of carbonates, phosphates, fluorides, hydroxides, oxides, and acetates containing W, Mo, Zr, Al, V, Ti, B, Co, Nb, La, Y, Ce, and Mg.

[0139] In some embodiments of the present invention, preferably, the amount of the second coating agent satisfies: 0 ≤ [n(J 2 )] / [n(Ni2)+n(Co2)+n(Mn2)]≤0.03; More preferably, the amount of the second coating agent satisfies: 0.001≤[n(J 2 )] / [n(Ni2)+n(Co2)+n(Mn2)]≤0.02.

[0140] In some embodiments of the present invention, preferably, the amounts of the first coating agent and the second coating agent satisfy: [n(J 1 )] / [n(Ni1)+n(Co1)+n(Mn1)]<[n(J 2 )] / [n(Ni2)+n(Co2)+n(Mn2)].

[0141] In some embodiments of the present invention, preferably, the conditions for the fourth sintering include: being carried out in an oxygen-containing atmosphere at a temperature of 200-1000°C for 5-20 hours. In the present invention, the oxygen-containing atmosphere includes, but is not limited to, an oxygen atmosphere or an air atmosphere.

[0142] The third aspect of this invention provides a multi-element cathode material provided in the first aspect, or the application of a multi-element cathode material prepared by the preparation method provided in the third aspect in a lithium-ion battery.

[0143] A fourth aspect of the present invention provides a positive electrode sheet, the positive electrode sheet comprising: a positive current collector and a positive additional layer disposed on at least one surface of the positive current collector;

[0144] The positive electrode additional layer is composed of a binder and a multi-element positive electrode material provided in the first aspect, or a multi-element positive electrode material prepared by the preparation method provided in the third aspect.

[0145] In some embodiments of the present invention, preferably, the loading of the multi-element cathode material is 14.5-16.5 mg / cm³. 2 For example, 14.5 mg / cm 2 15mg / cm 2 15.5 mg / cm 2 16mg / cm 2 16.5 mg / cm 2And any value within the range of any two values, preferably 15-16 mg / cm³. 2 .

[0146] The fifth aspect of the present invention provides a lithium-ion battery, the lithium-ion battery comprising the positive electrode sheet provided in the fourth aspect.

[0147] The present invention will be described in detail below through embodiments.

[0148] Unless otherwise specified, the room temperature referred to in this invention is 25±2℃.

[0149] In the following examples, the performance figures were obtained in the following ways:

[0150] (1) Particle size testing: laser particle size analyzer;

[0151] (2) Morphology test: obtained by scanning electron microscope of model S-4800 of Hitachi, Japan;

[0152] (3) Element content test: Measured by Shimadzu EPMA-8050G field emission electron probe microanalyzer;

[0153] (4) Specific surface area test: obtained by using a Tristar II3020 specific surface area tester from Micromertics, USA;

[0154] (5) XRD test: The results were obtained using a Smart Lab 9KW X-ray diffractometer from Rigaku Corporation, Japan; the grain size was obtained using SmartLab Studio II software.

[0155] (6) Compacted density test: The compacted density was obtained by using a BT-30 compacted density tester from Baxter Corporation;

[0156] (7) True density test: The true density was obtained by using the AccuPycⅡ1345 true density tester from Shanghai McMurray Instruments Co., Ltd.

[0157] (8) Electrochemical performance testing:

[0158] In the following examples and comparative examples, the electrochemical performance of the multi-element cathode material was tested using a 2025 coin cell.

[0159] The manufacturing process of the 2032 coin cell is as follows:

[0160] Electrode preparation: A homogeneous slurry is formed by thoroughly mixing a multi-element positive electrode material, acetylene black, and polyvinylidene fluoride (PVDF) at a mass ratio of 95:3:2 with an appropriate amount of N-methylpyrrolidone (NMP). The slurry is coated onto aluminum foil and dried at 120°C for 12 hours. Then, it is pressed into a positive electrode sheet with a diameter of 12 mm and a thickness of 120 μm using a pressure of 100 MPa. The loading of the multi-element positive electrode material is 15 mg / cm³. 2 .

[0161] Battery Assembly: In an argon-filled glove box with both water and oxygen content less than 5 ppm, the positive electrode, separator, negative electrode, and electrolyte were assembled into a 2025 coin cell and then left to stand for 6 hours. The negative electrode used a 17 mm diameter, 1 mm thick lithium metal sheet; the separator used a 25 μm thick polyethylene porous membrane (Celgard 2325); and the electrolyte was a mixture of equal parts ethylene carbonate (EC) and diethyl carbonate (DEC) containing 1 mol / L LiPF6.

[0162] Electrochemical performance testing:

[0163] The electrochemical performance of coin cells was tested at 25°C using the Newway battery testing system. The charge / discharge current density at 0.1C was 200 mA / g.

[0164] a. The prepared coin cells were subjected to charge-discharge tests at 25℃, 3.0-4.3V, and 0.1C to evaluate the initial charge-discharge specific capacity and initial charge-discharge efficiency of the materials;

[0165] b. The prepared coin cells were cycled twice at 45°C, 3.0-4.3V, and 0.1C, and then cycled 80 times at 1C to evaluate the high-temperature capacity retention of the material.

[0166] c. The prepared coin cells were cycled twice at 25°C, 3.0-4.3V, and 0.1C, and then cycled once each at 0.2C, 0.33C, 0.5C, and 1C. The rate performance of the multi-element cathode material was evaluated by the ratio of the initial discharge specific capacity at 0.1C to the discharge specific capacity at 1C. The initial discharge specific capacity at 0.1C is the discharge specific capacity of the coin cell in the first cycle, and the discharge specific capacity at 1C is the discharge specific capacity of the coin cell in the sixth cycle.

[0167] The physical properties of the precursor material A and the cathode material A obtained from preparation examples A1-A9 and preparation examples DA1-DA3, as well as the temperature T1 of the first sintering, are listed in Table 1.

[0168] Preparation Example A1

[0169] (I-1) The first nickel salt (nickel sulfate), the first cobalt salt (cobalt sulfate), the first manganese salt (manganese sulfate), and the first dopant (C) are added. 10 H5NbO 20 A mixed salt solution with a concentration of 2 mol / L was prepared; sodium hydroxide was dissolved to prepare a precipitant solution with a concentration of 8 mol / L; and 25 wt% ammonia water was used as a complexing agent solution. Nickel, cobalt, manganese, and niobium were introduced into the reactor in a co-current flow at a molar ratio of 90:7:3:0.2. The first co-precipitation reaction was carried out for 20 hours at a temperature of 60℃, a pH of 12.1, and a stirring speed of 60 rpm. Then, under a nitrogen atmosphere, the precursor slurry was filtered, washed, dried, and sieved to obtain material A1 precursor.

[0170] The amount of the first dopant mentioned above satisfies: [n(Nb)] / [n(Ni1)+n(Co1)+n(Mn1)]=0.002;

[0171] (I-2) After uniformly mixing the above-mentioned material A1 precursor and the first lithium salt (lithium hydroxide), the first sintering was carried out at 770°C for 18 hours under an oxygen atmosphere, and then naturally cooled to room temperature to obtain material A1 intermediate.

[0172] The amount of the first lithium salt used satisfies: [n(Li1)] / [n(Ni1)+n(Co1)+n(Mn1)]=1.04;

[0173] (I-3) The above-mentioned material A1 intermediate and the first coating agent (WO3) are uniformly mixed, and a second sintering is carried out at 600°C for 8 hours under an oxygen atmosphere. After natural cooling to room temperature, the mixture is sieved to obtain the positive electrode material A1, with the general formula Li. 1.04 Ni 0.9 Co 0.07 Mn 0.03 Nb 0.002 W 0.0015 O2.

[0174] The amount of the first coating agent mentioned above satisfies: n(W) / [n(Ni1)+n(Co1)+n(Mn1)]=0.0015.

[0175] Preparation Example A2

[0176] The method used in preparation example A1 is different,

[0177] In step (I-2), a first dopant is added and the type of the first dopant is replaced with Nb2O5. All other conditions remain the same, and the cathode material A2 is obtained.

[0178] Preparation Example A3

[0179] The method used in preparation example A1 is different,

[0180] The first dopant (containing niobium compound) consists of a first dopant and a second dopant, wherein the molar ratio of the first dopant to the second dopant is 2:1 based on metallic elements. The first dopant is C. 10 H5NbO 20 The second dopant, Nb2O5, was added in step (I-1) and added in step (I-2) under the same conditions to obtain cathode material A3.

[0181] Preparation Example A4

[0182] The method used in preparation example A1 is different,

[0183] Step (I-3) is omitted; the intermediate material A1 obtained in step (I-2) is directly used as the positive electrode material A4, with the general formula Li. 1.04 Ni 0.9 Co 0.07 Mn 0.03 Nb 0.002 O2.

[0184] Preparation Example A5

[0185] The method used in preparation example A1 is different,

[0186] In step (I-1), the pH was adjusted to 12.5 and the stirring speed was adjusted to 70 rpm. All other conditions remained the same, and the positive electrode material A5 was obtained.

[0187] Preparation Example A6

[0188] The method used in preparation example A1 is different,

[0189] In step (I-1), the first dopant is replaced with La(NO3)3, and the other conditions remain the same, to obtain the cathode material A6.

[0190] Preparation Example A7

[0191] The method used in preparation example A1 is different,

[0192] In step (I-1),

[0193] The amount of the first dopant mentioned above satisfies: [n(Nb)] / [n(Ni1)+n(Co1)+n(Mn1)]=0.02, and the other conditions are the same, thus obtaining the cathode material A7.

[0194] Preparation Example A8

[0195] The method used in preparation example A1 is different,

[0196] In step (I-2), the temperature of the first sintering is replaced with 870℃, and the other conditions are the same, to obtain the cathode material A8.

[0197] Preparation Example A9

[0198] The method used in preparation example A1 is different,

[0199] In step (I-1), the first nickel salt (nickel sulfate), the first cobalt salt (cobalt sulfate), and the first manganese salt (manganese sulfate) are replaced with nickel, cobalt, and manganese in a molar ratio of 70:20:10.

[0200] In step (I-2), the temperature of the first sintering is changed to 860℃ depending on the Ni content, while the other conditions remain the same, to obtain the cathode material A9.

[0201] Preparation example DA1

[0202] The method used in preparation example A1 is different,

[0203] In step (I-1), the first dopant is replaced with Al(NO3)3, and the other conditions remain the same, to obtain the cathode material DA1.

[0204] Preparation example DA2

[0205] The method used in preparation example A1 is different,

[0206] In step (I-1), the first dopant is not added, and the intermediate material A obtained in step (I-2) is directly used as the positive electrode material DA2.

[0207] Preparation example DA3

[0208] The method used in preparation example A1 is different,

[0209] In step (I-1), the amount of the first dopant is replaced with...

[0210] [n(Nb)] / [n(Ni1)+n(Co1)+n(Mn1)]=0.0005, and with all other conditions remaining the same, the cathode material DA3 is obtained.

[0211] Table 1

[0212]

[0213] Continued from Table 1

[0214]

[0215] Note: Equation VII is:

[0216] Taking Example 1 as an example,

[0217] 2- The temperature of the first sintering is T1, ℃.

[0218] As shown in Table 1, by adjusting the rotation speed and pH value of the first coprecipitation reaction, a specific electron microscopy particle size P can be obtained. MA50 A precursor material A with specific BET; simultaneously, by combining the first sintering temperature with Equation VII, it is possible to obtain a particle size P with a specific electron microscopy diameter. A50 And primary particle size D PSx The positive electrode material A.

[0219] The physical properties of the precursor material B and the cathode material B prepared in preparation examples B1-B10 and DB1-DB4 are listed in Table 2.

[0220] Preparation Example B1

[0221] (II-1) Prepare mixed salt solutions with a concentration of 2 mol / L for the second nickel salt (nickel sulfate), the second cobalt salt (cobalt sulfate), the second manganese salt (manganese sulfate), and the second dopant (aluminum nitrate); dissolve sodium hydroxide to prepare a precipitant solution with a concentration of 8 mol / L; and use 25 wt% ammonia water as a complexing agent solution. The above solutions are fed into the reactor in a parallel flow manner according to the molar ratio of nickel, cobalt, manganese, and aluminum of 90:7:3:0.3. The first co-precipitation reaction is carried out for 20 h at a temperature of 60℃, a pH of 12.8, and a stirring speed of 80 rpm. Then, under a nitrogen atmosphere, the precursor slurry is filtered, washed, dried, and sieved to obtain material B1 precursor.

[0222] The amount of the second dopant mentioned above satisfies: [n(Al)] / [n(Ni2)+n(Co2)+n(Mn2)]=0.003;

[0223] (II-2) After uniformly mixing the above-mentioned material B1 precursor and the second lithium salt (lithium hydroxide), the third sintering was carried out at 820°C for 18 hours in an oxygen atmosphere and then naturally cooled to room temperature to obtain material B1 intermediate.

[0224] The amount of the second lithium salt used satisfies: [n(Li2)] / [n(Ni2)+n(Co2)+n(Mn2)]=1.04;

[0225] (II-3) The above-mentioned material B1 intermediate and the second coating agent (Nb2O5) were uniformly mixed and subjected to a fourth sintering at 700°C for 8 hours under an oxygen atmosphere. After natural cooling to room temperature, the mixture was sieved to obtain the positive electrode material B1, with the general formula Li. 1.04 Ni 0.9 Co 0.07 Mn0.03 Al 0.003 Nb 0.002 O2.

[0226] The amount of the second coating agent mentioned above satisfies: n(Nb) / [n(Ni2)+n(Co2)+n(Mn2)]=0.002.

[0227] Preparation Example B2

[0228] The method used in preparation example B1 is different,

[0229] In step (II-2), a second dopant is added and replaced with Al2O3, while the other conditions remain the same, to obtain the cathode material B2.

[0230] Preparation Example B3

[0231] The method used in preparation example B1 is different,

[0232] Step (II-3) is omitted; the intermediate material B1 obtained in step (II-2) is directly used as the positive electrode material B3, with the general formula Li. 1.04 Ni 0.9 Co 0.07 Mn 0.03 Al 0.003 O2.

[0233] Preparation Example B4

[0234] The method used in preparation example B1 is different,

[0235] In step (II-1), the pH was adjusted to 12.1 and the stirring speed was adjusted to 60 rpm. All other conditions remained the same, and the positive electrode material B4 was obtained.

[0236] Preparation Example B5

[0237] The method used in preparation example B1 is different,

[0238] The second dopant was replaced with aluminum oxide and tungsten oxide in a molar ratio of 3:1, while all other conditions remained the same, to obtain cathode material B5.

[0239] Preparation Example B6

[0240] The method used in preparation example B1 is different,

[0241] By replacing the second dopant with tungsten oxide and keeping all other conditions the same, cathode material B6 was obtained.

[0242] Preparation Example B7

[0243] The method used in preparation example B1 is different,

[0244] In step (II-1),

[0245] The amount of the second dopant mentioned above satisfies: [n(Al)] / [n(Ni2)+n(Co2)+n(Mn2)]=0.03, and the other conditions are the same, thus obtaining the cathode material B7.

[0246] Preparation Example B8

[0247] The method used in preparation example B1 is different,

[0248] In step (II-1),

[0249] The amount of the second dopant mentioned above satisfies: [n(Al)] / [n(Ni2)+n(Co2)+n(Mn2)]=0.001, and the other conditions are the same, thus obtaining the cathode material B8.

[0250] Preparation Example B9

[0251] The method used in preparation example B1 is different,

[0252] In step (II-1), the second nickel salt (nickel sulfate), the second cobalt salt (cobalt sulfate), and the second manganese salt (manganese sulfate) are replaced with nickel, cobalt, and manganese in a molar ratio of 85:5:10.

[0253] In step (II-2), the sintering temperature was changed to 860℃, while the other conditions remained the same, and the cathode material B9 was obtained.

[0254] Preparation Example B10

[0255] The method used in preparation example B1 is different,

[0256] In step (II-3), the amount of the second coating agent described above satisfies the following:

[0257] With n(Nb) / [n(Ni2)+n(Co2)+n(Mn2)]=0.015 and all other conditions remaining the same, the cathode material B10 is obtained.

[0258] Preparation example DB1

[0259] The method used in preparation example B1 is different,

[0260] In step (II-1), without adding a second dopant, and with all other conditions remaining the same, the cathode material DB1 is obtained.

[0261] Preparation example DB2

[0262] The method used in preparation example B1 is different,

[0263] In step (II-1), no second dopant is added, and the intermediate material B obtained in step (II-2) is directly used as the positive electrode material DB2.

[0264] Preparation example DB3

[0265] The method used in preparation example B1 is different,

[0266] In step (II-1), the second dopant is replaced with Mg(NO3)2, where the bond energy of the Mg-O bond is 356 kJ / mol. Under the same conditions, the cathode material DB3 is obtained.

[0267] Preparation example DB4

[0268] The method used in preparation example B1 is different,

[0269] In step (II-1), the pH was adjusted to 13.1, the stirring speed was adjusted to 100 rpm to increase the crushing intensity, and the other conditions remained the same, resulting in D. B50 DB4 is a cathode material with a thickness of 3.4 μm.

[0270] Table 2

[0271] Composition of cathode material B Preparation Example B1 <![CDATA[Li 1.04 Ni 0.9 Co 0.07 Mr 0.03 Al 0.003 No 0.002 O2]]> Preparation Example B2 <![CDATA[Li 1.04 Ni 0.9 Co 0.07 Mr 0.03 Al 0.003 No 0.002 O2]]> Preparation Example B3 <![CDATA[Li 1.04 Ni 0.9 Co 0.07 Mr 0.03 Al 0.003 O2]]> Preparation Example B4 <![CDATA[Li 1.04 Ni 0.9 Co 0.07 Mr 0.03 Al 0.003 No 0.002 O2]]> Preparation Example B5 <![CDATA[Li 1.04 Ni 0.9 Co 0.07 Mr 0.03 Al 0.00225 W 0.00075 No 0.002 O2<!-- 17 --> ]]> Preparation Example B6 <![CDATA[Li 1.04 Ni 0.9 Co 0.07 Mr 0.03 W 0.003 No 0.002 O2]]> Preparation Example B7 <![CDATA[Li 1.04 Ni 0.9 Co 0.07 Mr 0.03 Al 0.03 No 0.002 O2]]> Preparation Example B8 <![CDATA[Li 1.04 Ni 0.9 Co 0.07 Mr 0.03 Al 0.0001 No 0.002 O2]]> Preparation Example B9 <![CDATA[Li 1.04 Ni 0.85 Co 0.05 Mr 0.1 Al 0.003 No 0.002 O2]]> Preparation Example B10 <![CDATA[Li 1.04 Ni 0.9 Co 0.07 Mr 0.03 Al 0.003 No 0.0015 O2]]> Preparation example DB1 <![CDATA[Li 1.04 Ni 0.9 Co 0.07 Mr 0.03 No 0.002 O2]]> Preparation example DB2 <![CDATA[Li 1.04 Ni 0.9 Co 0.07 Mr 0.03 O2]]> Preparation example DB3 <![CDATA[Li 1.04 Ni 0.9 Co 0.07 Mr 0.03 Mg 0.003 No 0.002 O2]]> Preparation example DB4 <![CDATA[Li 1.04 Ni 0.9 Co 0.07 Mr 0.03 Al 0.003 No 0.002 O2]]>

[0272] Continued from Table 2

[0273]

[0274]

[0275] As shown in Table 2, by adjusting the rotation speed and pH value of the second coprecipitation reaction, a specific electron microscopy particle size P can be obtained. MB50 And a specific BET material precursor B, thereby obtaining P with a suitable electron microscopy particle size. B50 The positive electrode material B.

[0276] The physical properties of the multi-element cathode materials prepared in Examples 1-20 and Comparative Examples 1-7 are listed in Table 3.

[0277] Example 1

[0278] The above-mentioned cathode material A1 and cathode material B1 were mixed at a mass ratio of 7:3 at room temperature for 5 hours to obtain a multi-element cathode material P1. The structural parameters of the above-mentioned multi-element cathode material P1 are shown in Table 3.

[0279] Among them, the scanning electron microscope (SEM) image of the aforementioned multi-element cathode material P1 is as follows: Figure 1 As shown. By Figure 1It can be seen that in the multi-component cathode material P1, the mixing of large-particle cathode material A1 and small-particle cathode material B1 can achieve a uniform distribution of large and small particles in the multi-component cathode material P1.

[0280] Examples 2-20 and Comparative Examples 1-7

[0281] The method of Example 1 is different except that the specific types and mixing ratios of large particle cathode material A and small particle cathode material B are different, as shown in Table 3. The multi-element cathode materials P2-P20 and DP1-DP7 are obtained respectively. The structural parameters of the multi-element cathode materials P2-P20 and DP1-DP7 are shown in Table 3.

[0282] Table 3

[0283]

[0284] Note: The mass ratio of cathode material A to cathode material B in a 3-component cathode material.

[0285] Continued from Table 3

[0286]

[0287]

[0288] Note: Equation II of 4- is: Taking Example 1 as an example, R Ni / [5000×(R M 1 -R Ni )]=0.056 / [5000×(0.064-0.056)]=0.0014; Equation IV is: 0.05≤C M 1 ×R M 1 ×1000≤1,

[0289] Taking Example 1 as an example, C M 1 ×R M 1 ×1000=0.002×0.064×1000=0.128;

[0290] Equation 6-V is: Taking Example 1 as an example, C M 1 ×[R M 1 / R Ni ]×[n Ni 1 / n Ni 2= 0.002 × [0.064 / 0.056] × [0.9 / 0.9] = 0.0023.

[0291] Continued from Table 3

[0292]

[0293]

[0294] Note: Equation VI is: 1550 × D PSx ×W A +750×(1-W A )≤D XRD ≤1750×D PSx ×W A +850×(1-W A );

[0295] Taking Example 1 as an example, 1550×D PSX ×W A +750×(1-W A )=1550×0.32×0.7+750×(1-0.7)=572;1750×D PSx ×W A +850×(1-W A =1750×0.32×0.7+850×(1-0.7)=647.

[0296] As shown in Table 3, by adjusting the electron microscopy particle size P of cathode material A... A50 Electron microscopy particle size P of cathode material B B50 The mass ratio of cathode material A to cathode material B, along with the resulting multi-element cathode material, gives it a higher compaction relative density, thereby increasing the volumetric energy density of the cathode sheet.

[0297] Furthermore, by controlling the primary particle size D of cathode material A in the multi-element cathode material... PSx And a scheme where the mass ratio of cathode material A is within a preferred range, such that the grain size D of the multi-element cathode material is... XRD satisfy

[0298] Electrochemical performance testing

[0299] The present invention tested the electrochemical performance of the multi-element cathode materials prepared in Examples 1-20 and Comparative Examples 1-7, including the 0.1C initial discharge specific capacity, 1C discharge specific capacity, rate performance and cycle performance; wherein, the 1C rate in Table 4 is the capacity tested at room temperature of 25℃, and the specific test results are shown in Table 4.

[0300] Among them, the cycling performance of the multi-element cathode materials prepared in Example 1 and Comparative Example 1 at 1C rate is as follows: Figure 2 As shown, the test temperature was 45℃, and the voltage range was 3.0-4.3V. Figure 2 It can be seen that, compared with Comparative Example 1, the multi-element cathode material P1 prepared in Example 1 has excellent cycle performance and capacity performance.

[0301] Table 4

[0302]

[0303]

[0304] Note: The mass ratio of cathode material A to cathode material B in a 3-component cathode material.

[0305] As shown in Table 4, when element M is doped into cathode material A... 1 Ionic radius R M 1 At ≥0.058nm, the rate performance of the multi-element cathode material is improved. Examples 2-3 illustrate the effect of the mixing ratio of cathode material A and cathode material B. The number of large particles affects the compaction relative density, resulting in slightly poorer electrode preparation and a slight decrease in capacity and rate cycling. Examples 4-5 and Example 12 show that liquid-phase doping of the precursor of material A or the precursor of material B is more uniform than solid-phase doping by sintering, and has a better effect on improving rate and cycling performance. Examples 6, 13, and 20 show that the loss of coating elements or a reduction in the coating amount of cathode material A or cathode material B will lead to a decrease in cycling performance. Examples 7 and 14 show that the precursor preparation method affects the structure of the multi-element cathode material, and the electron microscopy particle size P of cathode material A is also affected. A50 The electron microscopy particle size P of the cathode material B is too small. B50 Excessive values ​​will affect the compaction relative density of the material, impacting electrode fabrication and leading to decreased rate capability or cycle life. Example 8 illustrates the ionic radius R in cathode material A. M 1 Larger dopant element M 1 Fewer elements can be doped into the crystal lattice, making it difficult to enter the lattice, but a small amount of doping can achieve the same effect, requiring less dopant; Examples 15-16 illustrate the dopant element M. 2 Besides Al, the other doping elements are M 2 Satisfy M 2 The bond energy of -O meets the requirements and can achieve the effect of improving cycle life, but it is slightly worse than Al doping. Examples 9 and 17 illustrate that excessive doping elements will affect the material's capacity, leading to a decrease in capacity, and excessive presence in the crystal lattice will affect lithium-ion transport, resulting in a decrease in rate capability. Example 10 illustrates that the sintering temperature of cathode material A is too high, and the primary particle size D...PSx If the doping level is too high, the capacity of the multi-element cathode material decreases, and the rate capability deteriorates; Example 18 illustrates the doping element M in cathode material B. 2 Insufficient doping does not conform to formula (V), resulting in poor cycle performance of the multi-element cathode material; Examples 11 and 19 illustrate that cathode material A and cathode material B have significant differences in composition, resulting in capacity mismatch and low material capacity.

[0306] In Comparative Example 1, both cathode materials A and B are undoped, resulting in poor rate capability and cycle life of the multi-element cathode material; in Comparative Example 2, cathode material A is undoped, leading to poor rate capability of the multi-element cathode material; in Comparative Example 3, cathode material B is undoped, resulting in poor cycle life of the multi-element cathode material; in Comparative Example 4, both cathode materials A and B are undoped and uncoated, resulting in even worse rate capability and cycle life of the multi-element cathode material; in Comparative Example 5, cathode material A has relatively little doping, failing to meet equation (II) and thus not achieving a good doping effect, resulting in poor rate capability improvement; in Comparative Example 6, the doped element in cathode material B has weak bonding with O, resulting in poor cycle life improvement; Comparative Example 7 illustrates that the P of the cathode material... 50 (P A50 and P B50 ) and D 50 (D A50 and D B50 ) different, D 50 It can be controlled through the breakage situation, but P 50 Primarily controlled through sintering and precursor processes, this invention requires control of P. 50 Optimal results can only be achieved within a reasonable range.

[0307] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A multi-element cathode material, characterized in that, The multi-element cathode material includes: cathode material A having the composition shown in Formula I and cathode material B having the composition shown in Formula III, wherein the electron microscopy particle size P of cathode material A is... A50 The electron microscopy particle size P of the cathode material B is 10-18 μm. B50 Its thickness is 2-6.5 μm; Li a1 Ni x1 Co y1 Mn z1 M 1 b1 J 1 c1 O2(I), where 0.9≤ a 1≤1.1, 0.5≤x1<1, 0< y 1 < 0.5, 0 < z 1 < 0.5, 0 < b 1≤0.02, 0≤ c 1≤0.02, and x 1+ y 1+ z 1=1; M 1 satisfy: (II), R M 1 For M 1 The ionic radius, in nm; R Ni For Ni 3+ The ionic radius is 0.056 nm; C M 1 M in the positive electrode material A 1 Relative to the molar ratio of (Ni+Co+Mn); C M 1 The average value was obtained by cross-sectional electron probe microanalysis. Fifty particles were selected from cathode material A for electron probe surface scanning test. The test range of cathode material A is the interior greater than 1 μm from the surface. If there is doping element enrichment in the interior or at the grain boundary, it needs to be deducted. Only the uniformly doped part is taken. Li a2 Ni x2 Co y2 Mn z2 M 2 b2 J 2 c2 O2(Ⅲ), where 0.9≤ a 2≤1.1, 0.5≤ x 2 < 1, 0 < y 2 < 0.5, 0 < z 2 < 0.5, 0 < b 2≤0.03, 0≤ c 2≤0.03, and x 2+ y 2+ z 2=1; M 2 Selected from those that can form M with O 2 Elements with -O bonds and bond energies ≥ 395 kJ / mol; J 1 and J 2 Each element is independently selected from at least one of W, Mo, Zr, Al, V, Ti, B, Co, Nb, La, Y, Ce, and Mg; The grain size D of the multi-element cathode material was obtained by XRD testing. XRD Satisfaction VI: 1550×D PSx ×W A +750×(1-W A )≤D XRD ≤1750×D PSx ×W A +850×(1-W A ) (VI), where D PSx W represents the primary particle size of the cathode material A, in μm. A The mass percentage of cathode material A in the multi-element cathode material; Wherein, the primary particle size D of the positive electrode material A PSx It is 0.2-0.5μm.

2. The multi-element cathode material according to claim 1, wherein, The positive electrode material A has P A50 The P-value of the cathode material B is 11-17 μm. B50 Its thickness is 2.5-4.5 μm; And / or, in Equation I, 0.9 ≤ a 1≤1.05, 0.7≤ x 1 < 1, 0.03 ≤ y 1≤0.3, 0.01≤ z 1≤0.25, 0.001≤ b 1≤0.015, 0.001≤ c 1≤0.015, and x 1+ y 1+ z 1 = 1; And / or, in Formula I, the element M 1 It is selected from at least one element from Mg, Nb, W, La, Ce, Zr, Y and Ti; And / or, in Equation III, 0.9 ≤ a 2≤1.05, 0.7≤ x 2 < 1, 0.02 ≤ y 2≤0.25, 0.01≤ z 2≤0.3, and x 2+ y 2+ z 2 = 1, 0.001 ≤ b 2≤0.03, 0.001≤ c 2≤0.02; And / or, in Formula III, the element M 2 It is selected from at least one element from Al, V, Si, La, Y, Ti, and Zr.

3. The multi-element cathode material according to claim 2, wherein, In Equation I, 1.01 ≤ a 1≤1.05, 0.8≤ x 1≤0.95, 0.05≤ y 1≤0.2, 0.02≤ z 1≤0.2, and x 1+ y 1+ z 1 = 1; In formula I, the element M 1 At least one element selected from Mg, Nb, W, Zr, and Ti; And / or, in Equation III, 1.01 ≤ a 2≤1.05, 0.8≤ x 2≤0.95, 0.05≤ y 2≤0.2, 0.05≤ z 2≤0.2, and x 2+ y 2+ z 2 = 1, 0.002 ≤ b 2≤0.02; And / or, in Formula III, the element M 2 The elements are selected from Al and non-Al elements, and the non-Al elements are selected from at least one element selected from V, Si, La, Y, Ti, and Zr.

4. The multi-element cathode material according to claim 2, wherein, In Formula I c 1 < Equation III c 2.

5. The multi-element cathode material according to claim 1, wherein, In Formula II, the element M 1 ionic radius R M 1 ≥0.058nm; And / or, the element M 1 It also satisfies: 0.05≤C M 1 ×R M 1 ×1000≤1(Ⅳ) And / or, the element M 2 satisfy: (V); where n Ni 1 The molar ratio of Ni to (Ni+Co+Mn) in the cathode material A; n Ni 2 The molar ratio of Ni to (Ni+Co+Mn) in the cathode material B; C M 2 M in the positive electrode material B 2 Relative to the molar ratio of (Ni+Co+Mn); C M 2 The average value was obtained by cross-sectional electron probe microanalysis. Fifty particles were selected from cathode material B for electron probe surface scanning. The test range of cathode material B was the interior greater than 0.5 μm from the surface. If there was dopant enrichment in the interior or at the grain boundary, it was deducted. Only the uniformly doped part was taken.

6. The multi-element cathode material according to claim 5, wherein, In Formula II, the element M 1 ionic radius R M 1 The wavelength ranges from 0.058 to 0.075 nm.

7. The multi-element cathode material according to claim 1, wherein, The grain size D of the multi-element cathode material XRD 500-750 Å; And / or, in the multi-element cathode material, the mass ratio of cathode material A to cathode material B is 6-9:4-1; And / or, the compacted relative density of the multi-element cathode material λ ≥70%, of which, λ=ρ P / ρ S , ρ P The density of the multi-element cathode material under a pressure of 20 kN is expressed in g / cm³. 3 ; ρ S The true density of the multi-element cathode material is expressed in g / cm³. 3 .

8. The multi-element cathode material according to claim 7, wherein, The grain size D of the multi-element cathode material XRD 500-750 Å; And / or, in the multi-element cathode material, the mass ratio of cathode material A to cathode material B is (lg P) A50 )-P A50 :(lg P B50 )-P B50 ; And / or, the compacted relative density of the multi-element cathode material λ ≥74%.

9. A method for preparing a multi-element cathode material, characterized in that, The preparation method includes: mixing cathode material A with the composition shown in Formula I and cathode material B with the composition shown in Formula III to obtain a multi-element cathode material; Among them, the electron microscopy particle size P of the positive electrode material A A50 The electron microscopy particle size P of the cathode material B is 10-18 μm. B50 Its thickness is 2-6.5 μm; Li a1 Ni x1 Co y1 Mn z1 M 1 b1 J 1 c1 O2(I), where 0.9≤ a 1≤1.1, 0.5≤x1<1, 0< y 1 < 0.5, 0 < z 1 < 0.5, 0 < b 1≤0.02, 0≤ c 1≤0.02, and x 1+ y 1+ z 1=1; M 1 satisfy: (II), R M 1 For M 1 The ionic radius, in nm; R Ni For Ni 3+ The ionic radius is 0.056 nm; C M 1 M in the positive electrode material A 1 Relative to the molar ratio of (Ni+Co+Mn); C M 1 The average value was obtained by cross-sectional electron probe microanalysis. Fifty particles were selected from cathode material A for electron probe surface scanning test. The test range of cathode material A is the interior greater than 1 μm from the surface. If there is doping element enrichment in the interior or at the grain boundary, it needs to be deducted. Only the uniformly doped part is taken. Li a2 Ni x2 Co y2 Mn z2 M 2 b2 J 2 c2 O2(Ⅲ), where 0.9≤ a 2≤1.1, 0.5≤ x 2 < 1, 0 < y 2 < 0.5, 0 < z 2 < 0.5, 0 < b 2≤0.03, 0≤ c 2≤0.03, and x 2+ y 2+ z 2=1; M 2 Selected from those that can form M with O 2 Elements with -O bonds and bond energies ≥ 395 kJ / mol; J 1 and J 2 Each element is independently selected from at least one of W, Mo, Zr, Al, V, Ti, B, Co, Nb, La, Y, Ce, and Mg; The grain size D of the multi-element cathode material was obtained by XRD testing. XRD Satisfaction VI: 1550×D PSx ×W A +750×(1-W A )≤D XRD ≤1750×D PSx ×W A +850×(1-W A ) (VI), where D PSx W represents the primary particle size of the cathode material A, in μm. A The mass percentage of cathode material A in the multi-element cathode material; Wherein, the primary particle size D of the positive electrode material A PSx It is 0.2-0.5μm.

10. The preparation method according to claim 9, wherein, The mass ratio of the positive electrode material A to the positive electrode material B is 6-9:4-1; And / or, the mixing conditions include: a temperature of 20-60°C and a time of 0.5-10h.

11. The preparation method according to claim 10, wherein, The mass ratio of the positive electrode material A to the positive electrode material B is (lg P) A50 )-P A50 :(lg P B50 )-P B50 .

12. The preparation method according to claim 9, wherein, The preparation method further includes: obtaining the cathode material A through the following steps: (I-1) In the presence of a first solvent, the components in component C are mixed and subjected to a first coprecipitation reaction to obtain a precursor of material A, wherein component C contains a first nickel salt, a first cobalt salt, a first manganese salt, a first precipitant and a first complexing agent; (I-2) The precursor of material A is mixed with each component in component D and subjected to a first sintering to obtain an intermediate of material A, wherein component D contains a first lithium salt; (I-3) The intermediate material A and the first coating agent are mixed and subjected to a second sintering to obtain a second sintered product, wherein the first coating agent contains the element J. 1 ; Component C and / or component D further contain a first dopant, wherein the first dopant contains element M. 1 ; The intermediate material A or the second sintered product is used as the positive electrode material A.

13. The preparation method according to claim 12, wherein, The conditions for the first coprecipitation reaction include: temperature 40-80℃, time 5-40h, rotation speed 40-80rpm, and pH value 10-12.5; And / or, the electron microscopic grain size P of the precursor of material A. MA50 The thickness is 10-18 μm, and the BET thickness is 4-15 μm. 2 / g; And / or, the amount of the first lithium salt satisfies: 0.9≤[n(Li1)] / [n(Ni1)+n(Co1)+n(Mn1)]≤1.1; And / or, the component C contains at least a portion of the first dopant; And / or, the element M 1 ionic radius R M 1 ≥0.058μm; And / or, the first dopant is selected from those containing the element M. 1 At least one of the following: oxides, fluorides, carbonates, hydroxides, and acetates; And / or, the amount of the first dopant satisfies: 0 < [n(M 1 )] / [n(Ni1)+n(Co1)+n(Mn1)]≤0.02; And / or, the first coating agent is selected from those containing the element J. 1 At least one of the following: carbonate, phosphate, fluoride, hydroxide, oxide, and acetate; And / or, the amount of the first coating agent satisfies: 0 ≤ [n(J 1 )] / [n(Ni1)+n(Co1)+n(Mn1)]≤0.

02.

14. The preparation method according to claim 13, wherein, The amount of the first lithium salt satisfies: 0.9≤[n(Li1)] / [n(Ni1)+n(Co1)+n(Mn1)]≤1.05; And / or, the element M 1 ionic radius R M 1 Its thickness ranges from 0.058 to 0.075 μm. And / or, the first dopant is selected from at least one of oxides, fluorides, carbonates, hydroxides and acetates containing Mg, Nb, W, La, Ce, Zr, Y and Ti; And / or, the amount of the first dopant satisfies: 0.001≤[n(M 1 )] / [n(Ni1)+n(Co1)+n(Mn1)]≤0.015; And / or, the first coating agent is selected from at least one of carbonates, phosphates, fluorides, hydroxides, oxides, and acetates containing W, Mo, Zr, Al, V, Ti, B, Co, Nb, La, Y, Ce, and Mg; And / or, the amount of the first coating agent satisfies 0.001 ≤ [n(J 1 )] / [n(Ni1)+n(Co1)+n(Mn1)]≤0.

015.

15. The preparation method according to claim 14, wherein, The amount of the first lithium salt satisfies: 1.01≤[n(Li1)] / [n(Ni1)+n(Co1)+n(Mn1)]≤1.

05.

16. The preparation method according to claim 12, wherein, In step (I-2), the temperature T1 of the first sintering satisfies equation VII: （Ⅶ）； Where, n Ni 1 The molar ratio of the first nickel salt in the mixture of the first nickel salt, the first cobalt salt, and the first manganese salt, calculated by metal element; n Mn 1 P represents the molar ratio of the first manganese salt in the mixture of the first nickel salt, the first cobalt salt, and the first manganese salt, calculated by metal element. MA50 The electron microscopic particle size of the precursor material A is denoted as μm.

17. The preparation method according to claim 16, wherein, In step (I-2), the conditions for the first sintering include: being carried out in an oxygen-containing atmosphere at a temperature of 600-1200℃ for 10-30 hours; And / or, in step (I-3), the conditions for the second sintering include: being carried out in an oxygen-containing atmosphere at a temperature of 200-1000℃ for 5-20h.

18. The preparation method according to claim 12, wherein, The preparation method further includes: obtaining the cathode material B through the following steps: (II-1) In the presence of a second solvent, the components in component E are mixed and subjected to a second coprecipitation reaction to obtain a precursor of material B, wherein component E contains a second nickel salt, a second cobalt salt, a second manganese salt, a second precipitant, and a second complexing agent. (II-2) The precursor of material B is mixed with each component in component F and subjected to a third sintering to obtain intermediate material B, wherein component F contains a second lithium salt; (II-3) The intermediate material B is mixed with the second coating agent and subjected to a fourth sintering to obtain a fourth sintered product, wherein the second coating agent contains the element J. 2 ; The component E and / or the component F further contain a second dopant, the second dopant containing the element M. 2 ; The intermediate material B or the fourth sintering product is used as the positive electrode material B.

19. The preparation method according to claim 18, wherein, The rotation speed of the second coprecipitation reaction is greater than that of the first coprecipitation reaction, and the pH value of the second coprecipitation reaction is greater than that of the first coprecipitation reaction; And / or, the conditions for the second coprecipitation reaction include: temperature 40-80℃, time 5-40h, rotation speed 50-90rpm, and pH value 10.5-13; And / or, the electron microscopic grain size P of the precursor of material B. MB50 The range is 2-6.5 μm, and the BET range is 10-30 μm. 2 / g; And / or, the amount of the second lithium salt used satisfies: 0.9≤[n(Li2)] / [n(Ni2)+n(Co2)+n(Mn2)]≤1.1; And / or, the component E contains at least a portion of the second dopant; And / or, the second dopant is selected from those containing the element M. 2 At least one of the following: oxides, fluorides, carbonates, hydroxides, and acetates; And / or, the amount of the second dopant satisfies: 0 < [n(M 2 )] / [n(Ni2)+n(Co2)+n(Mn2)]≤0.03; And / or, the second coating agent is selected from those containing element J. 2 At least one of the following: carbonate, phosphate, fluoride, hydroxide, oxide, and acetate; And / or, the amount of the second coating agent satisfies: 0 ≤ [n(J 2 )] / [n(Ni2)+n(Co2)+n(Mn2)]≤0.03; And / or, the conditions for the third sintering include: being carried out in an oxygen-containing atmosphere at a temperature of 600-1200℃ for 10-30 hours; And / or, the conditions for the fourth sintering include: being carried out in an oxygen-containing atmosphere at a temperature of 200-1000℃ for 5-20 hours.

20. The preparation method according to claim 19, wherein, The amount of the second lithium salt used satisfies: 0.9≤[n(Li2)] / [n(Ni2)+n(Co2)+n(Mn2)]≤1.05; And / or, the second dopant is selected from at least one of oxides, fluorides, carbonates, hydroxides and acetates containing Al, V, Si, La, Y, Ti, Zr; And / or, the amount of the second dopant satisfies: 0.001≤[n(M 2 )] / [n(Ni2)+n(Co2)+n(Mn2)]≤0.03; And / or, the second coating agent is selected from at least one of carbonates, phosphates, fluorides, hydroxides, oxides, and acetates containing W, Mo, Zr, Al, V, Ti, B, Co, Nb, La, Y, Ce, and Mg; And / or, the amount of the second coating agent satisfies: 0.001≤[n(J 2 )] / [n(Ni2)+n(Co2)+n(Mn2)]≤0.02。 21. The preparation method according to claim 20, wherein, The amount of the second lithium salt used satisfies: 1.01≤[n(Li2)] / [n(Ni2)+n(Co2)+n(Mn2)]≤1.05; And / or, the second dopant is selected from at least one of oxides, fluorides, carbonates, hydroxides and acetates containing Al and non-Al elements, and the non-Al element is selected from at least one of V, Si, La, Y, Ti and Zr; And / or, the amount of the second dopant satisfies: 0.002≤[n(M 2 )] / [n(Ni2)+n(Co2)+n(Mn2)]≤0.02。 22. The preparation method according to claim 21, wherein, The amounts of the first coating agent and the second coating agent satisfy the following: [n(J 1 )] / [n(Ni1)+n(Co1)+n(Mn1)]<[n(J) 2 )] / [n(Ni2)+n(Co2)+n(Mn2)]。 23. The application of the multi-element cathode material according to any one of claims 1-8, or the multi-element cathode material prepared by the preparation method according to any one of claims 9-22, in lithium-ion batteries.

24. A positive electrode plate, characterized in that, The positive electrode sheet includes: a positive current collector and a positive additional layer disposed on at least one surface of the positive current collector; The positive electrode additional layer is composed of a binder and a multi-element positive electrode material as described in any one of claims 1-8, or a multi-element positive electrode material prepared by the preparation method described in any one of claims 9-22.

25. The positive electrode sheet according to claim 24, wherein, The loading of the multi-element cathode material is 14.5-16.5 mg / cm³. 2 .

26. The positive electrode sheet according to claim 25, wherein, The loading of the multi-element cathode material is 15-16 mg / cm³. 2 .

27. A lithium-ion battery, characterized in that, The lithium-ion battery includes: the positive electrode sheet as described in any one of claims 24-26.

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