Modified high-nickel positive electrode material, preparation method and application thereof, and lithium ion battery

Abstract

The application relates to the technical field of lithium ion batteries, in particular to a modified high-nickel positive electrode material and a preparation method and application thereof, and a lithium ion battery, the modified high-nickel positive electrode material comprising a base and a composite coating layer loaded on the base, the general formula of the base being; wherein the composite coating layer contains and generated in situ from residual lithium on the surface of the base and an additive with the general formula. The modified high-nickel positive electrode material not only effectively reduces the residual lithium on the surface of high-nickel positive electrode material particles, but also significantly improves the electrochemical stability and chemical stability of the modified high-nickel positive electrode material; meanwhile, the modified high-nickel positive electrode material is used in the lithium ion battery, and the electrochemical performance of the lithium ion battery can be effectively improved.

Description

Technical Field

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

[0002] In recent years, the global electric vehicle market has developed rapidly. However, the insufficient driving range and slow charging speed have hindered the popularization of electric vehicles, which has also placed higher demands on the energy density and power density of lithium-ion power batteries.

[0003] High-nickel ternary cathode materials are considered the most promising cathode materials for power batteries due to their high energy density, thus possessing significant commercial value. However, in practical applications, high-nickel ternary cathode materials still face many challenges, such as poor storage performance due to high residual lithium on the material surface; poor processability due to water absorption and gelation during slurry preparation; and the presence of high-valence transition metal ions (Ni) on the particle surface during charging. 4+ It exhibits strong oxidizing properties and readily undergoes severe side reactions with the electrolyte, leading to increased battery polarization and rapid capacity decay. Therefore, modification of high-nickel multi-element cathode materials is essential.

[0004] In China, the common practice is to wash high-nickel ternary materials with water and then sinter them at a lower temperature. This method effectively reduces the residual lithium content on the material surface, but it also significantly reduces the material's rate performance and cycle life. In recent years, an integrated wet process combining water washing and secondary sintering has been developed. This process reduces the residual lithium content on the material surface through water washing, while simultaneously forming a coating layer on the material particles through secondary sintering. Although this method is a highly efficient improvement on the original water washing approach, reducing the residual lithium content without sacrificing electrical performance, its drawbacks are still significant. These include issues such as the comprehensive utilization of circulating water during the water washing and coating process, and the handling of scale buildup during the drying process, leading to higher process costs. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of high residual lithium on the surface of high-nickel cathode materials, as well as the poor electrochemical performance, complex processes, and high costs of existing modified high-nickel cathode materials. This invention provides a modified high-nickel cathode material, its preparation method and application, and a lithium-ion battery. This modified high-nickel cathode material not only effectively reduces residual lithium on the surface of cathode material particles but also significantly improves the material's performance. Furthermore, the lithium-ion battery containing this modified high-nickel cathode material exhibits excellent electrochemical performance.

[0006] To achieve the above objectives, a first aspect of the present invention provides a modified high-nickel cathode material, the modified high-nickel cathode material comprising a matrix and a composite coating layer supported on the matrix, wherein the matrix has the general formula Li. (1+a) Ni x L y M z O2, L is selected from at least one of Co, Mn and Al, M is selected from at least one of Mg, Al, Ti, Zr, W, Mo, La, Y, Nb and Sr, x+y+z=1, 0.6≤x<1, 0.1≤y≤0.4, 0≤z≤0.2, 0≤a<0.5;

[0007] The composite coating layer contains residual lithium from the substrate surface and a general formula DF. b Li generated in situ by additives p DO (m+1) / 2 and Li n F and D are selected from at least one of Mg, Al, Ti, Zr, W, Mo, La, Y, Nb and Sr, 0.95≤p≤2.05, 0.98≤n≤1.02, and m and b are both natural numbers from 1 to 5.

[0008] Preferably, based on the total weight of the modified high-nickel cathode material, the content of the matrix is ​​90-99.9 wt%, preferably 95-98.5 wt%, more preferably 97-99.5 wt%; and the content of the composite coating layer is 0.1-10 wt%, preferably 0.2-5 wt%, more preferably 0.5-3 wt%.

[0009] Preferably, the Li in the composite coating layer p DO (m+1) / 2 and Li n The molar ratio of F is 1:(0.3-1)b, preferably 1:(0.8-0.9)b.

[0010] Preferably, based on the total weight of the substrate, the concentrations of lithium hydroxide and lithium carbonate on the substrate surface are set to m1 and m2, respectively, and the concentrations of lithium hydroxide and lithium carbonate on the surface of the modified high-nickel cathode material are set to m3 and m4, respectively, satisfying: The units for m1, m2, m3, and m4 are all ppm.

[0011] Preferably, Preferred

[0012] Preferably, Preferred

[0013] Preferably, in the XRD diffraction pattern of the modified high-nickel cathode material under CuKa radiation, 2θ shows obvious diffraction peaks at 38-38.8°, 44.5-45.5° and 64.8-66°, respectively.

[0014] Preferably, in the XRD diffraction pattern of the modified high-nickel cathode material obtained under CuKa radiation, the ratio β of the peak intensity of the (111) crystal plane to the peak intensity of the (003) crystal plane satisfies: 0.003≤β≤0.02, preferably 0.005≤β≤0.015, and more preferably 0.006≤β≤0.01.

[0015] A second aspect of this invention provides a method for preparing a modified high-nickel cathode material, the method comprising the following steps:

[0016] (1) Provide a general formula Ni γ L δ M ε (OH)2 high nickel precursor, wherein L is selected from at least one of Co, Mn and Al, M is selected from at least one of Mg, Al, Ti, Zr, W, Mo, La, Y, Nb and Sr, γ+δ+ε=1, 0.6≤γ<1, 0.1≤δ≤0.4, 0≤ε≤0.2;

[0017] (2) The high-nickel precursor and lithium source are mixed, and the resulting first mixture is calcined in a first oxygen-containing atmosphere to obtain a product with the general formula Li. (1+a) Ni x L y M z O2 high-nickel cathode material, wherein x+y+z=1, 0.6≤x<1, 0.1≤y≤0.4, 0≤z≤0.2, 0≤a<0.5;

[0018] (3) The high-nickel cathode material and the general formula DF b The additives are mixed, and the resulting second mixture is sintered in a second oxygen-containing atmosphere, allowing the additives to react in situ with residual lithium on the surface of the high-nickel cathode material to form a Li-containing compound on the surface of the high-nickel cathode material. p DO (m+1) / 2 and Li n A composite coating of F is used to obtain a modified high-nickel cathode material;

[0019] Wherein, D is selected from at least one of Mg, Al, Ti, Zr, W, Mo, La, Y, Nb and Sr, 0.95≤p≤2.05, 0.98≤n≤1.02, and m and b are both natural numbers from 1 to 5.

[0020] Preferably, in step (1), the high-nickel precursor is prepared by the following method:

[0021] (1-i) Provide a mixed metal salt solution containing Ni source, L source and M source; provide a precipitant solution and a complexing agent solution;

[0022] (1-ii) Under a non-oxidizing atmosphere, the mixed metal salt solution, precipitant solution and complexing agent solution are mixed and co-precipitated. The resulting precursor slurry is then filtered, washed and dried to obtain the high-nickel precursor.

[0023] The third aspect of this invention provides a modified high-nickel cathode material provided in the first aspect, or the modified high-nickel cathode material prepared by the preparation method provided in the second aspect, for use in lithium-ion batteries.

[0024] The fourth aspect of the present invention provides a lithium-ion battery, wherein the lithium-ion battery contains a modified high-nickel cathode material provided in the first aspect, or a modified high-nickel cathode material prepared by the preparation method provided in the second aspect.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) The modified high-nickel cathode material provided by the present invention includes a matrix and a composite coating layer, and the composite coating layer is defined to contain Li generated in situ from residual lithium on the surface of the matrix and additives. p DO (m+1) / 2 and Li n F not only effectively reduces residual lithium on the surface of high-nickel cathode material particles, but also significantly improves the electrochemical and chemical stability of modified high-nickel cathode materials.

[0027] Specifically, Li p DO (m+1) / 2 It is a typical lithium-ion conductor with good chemical stability, which can improve the lithium-ion transport rate across the particle surface, enhance rate performance, and effectively isolate the electrolyte from corrosion of the particle surface; Li n F exhibits good electrochemical and chemical stability, effectively protecting the particle surface and resisting high voltage.

[0028] (2) In the preparation method provided by the present invention, a dry coating process is adopted, that is, after the additive and the high nickel cathode material are sintered, they react in situ with the residual lithium on the surface to form a composite coating layer. This not only effectively reduces the residual lithium on the surface of the cathode material particles, but also improves the performance of the material. At the same time, the preparation method has the characteristics of simple process, easy process control, and low production cost, and is suitable for large-scale industrial production.

[0029] (3) The preparation method provided by the present invention, especially the wet precipitation method, uniformly distributes the doping element (i.e., M source) in the interior of the high nickel precursor, which is more conducive to the stability of the internal structure of the material, thereby improving the electrical performance of the modified high nickel cathode material.

[0030] (4) The preparation method provided by the present invention, especially by limiting a specific sintering temperature and a specific amount of additives, not only has a good lithium reduction effect, but also improves the capacity retention rate of the modified high-nickel cathode material;

[0031] (5) Using the modified high-nickel cathode material provided by the present invention in lithium-ion batteries can effectively improve the electrochemical performance of lithium-ion batteries, especially the energy density and power density. Attached Figure Description

[0032] Figure 1 These are XRD patterns of the modified high-nickel cathode materials prepared in Examples 1, 3, and 6;

[0033] Figure 2 This is an SEM image of the cross-section of the modified high-nickel cathode material S4 prepared in Example 4;

[0034] Figure 3 The graph shows the cycle performance of coin cells assembled from the modified high-nickel cathode materials provided in Examples 1-9 and Comparative Examples 1-2 at 45°C and 1C rate. Detailed Implementation

[0035] 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.

[0036] In this invention, unless otherwise specified, "first" and "second" do not indicate a sequence or 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 mixture" and "second mixture" are only used to indicate that these are not the same mixture.

[0037] The first aspect of this invention provides a modified high-nickel cathode material, the modified high-nickel cathode material comprising a matrix and a composite coating layer supported on the matrix, wherein the matrix has the general formula Li. (1+a) Ni x L y M zO2, L is selected from at least one of Co, Mn and Al, M is selected from at least one of Mg, Al, Ti, Zr, W, Mo, La, Y, Nb and Sr, x+y+z=1, 0.6≤x<1, 0.1≤y≤0.4, 0≤z≤0.2, 0≤a<0.5;

[0038] The composite coating layer contains residual lithium from the substrate surface and a general formula DF. b Li generated in situ by additives p DO (m+1) / 2 and Li n F and S are selected from at least one of Mg, Al, Ti, Zr, W, Mo, La, Y, Nb and Sr, 0.95≤p≤2.05, 0.98≤n≤1.02, and m and b are both natural numbers from 1 to 5.

[0039] In this invention, unless otherwise specified, the composite coating layer contains Li. p DO (m+1) / 2 and Li n F refers to the composite coating layer excluding Li. p DO (m+1) / 2 and Li n In addition to F, it may contain other components, or the composite coating layer may contain only Li. p DO (m+1) / 2 and Li n F.

[0040] In this invention, unless otherwise specified, L and M in the general formula of the matrix can be the same or different. Preferably, L and M are different, that is, L and M are selected from different metal types.

[0041] The inventors of this invention have discovered that loading Li-containing materials onto the surface of a substrate... p DO (m+1) / 2 and Li n The composite coating of F can effectively reduce residual lithium on the substrate surface, and on the other hand, Li p DO (m+1) / 2 and Li n F directly coats the surface of the substrate to form a composite coating layer, which can avoid side reactions between the substrate and the electrolyte; at the same time, Li p DO (m+1) / 2 It is a typical lithium-ion conductor. When coated on the substrate surface, it can increase the lithium-ion transport rate through the particle surface, improve rate performance, and effectively isolate the electrolyte from corrosion of the particle surface; Li n F exhibits good electrochemical and chemical stability, effectively protecting the particle surface and resisting high voltage.

[0042] In some embodiments of the present invention, preferably, based on the total weight of the modified high-nickel cathode material, the content of the matrix is ​​90-99.9 wt%, for example, 90 wt%, 93.5 wt%, 95 wt%, 95.5 wt%, 97.1 wt%, 98.5 wt%, 99.5 wt%, 99.9 wt%, and any value within any range of any two values, preferably 95-98.5 wt%, more preferably 97-99.5 wt%; the content of the composite coating layer is 0.1-10 wt%, for example, 0.1 wt%, 0.2 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 3 wt%, 5 wt%, 7 wt%, 10 wt%, and any value within any range of any two values, preferably 0.2-5 wt%, more preferably 0.5-3 wt%.

[0043] In some embodiments of the present invention, preferably, the thickness of the composite coating layer is 1 nm, for example, 1 nm, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 40 nm, 50 nm, and any value in the range of any two values, preferably 5-30 nm.

[0044] In this invention, unless otherwise specified, the thickness parameter of the composite coating layer is tested using conventional methods, including: first, preparing a sample by ion milling the test material (i.e., the modified high-nickel cathode material); then, observing the position of the composite coating layer using a scanning electron microscope; and finally, determining the thickness of the composite coating layer by line scanning using energy dispersive spectroscopy. Specifically, the particle thickness is determined by randomly selecting 20 regions along the circumference of the particle for testing and averaging the measurements. To improve measurement accuracy, in this invention, 60-80 particles are selected for testing each time.

[0045] In some embodiments of the present invention, preferably, the Li in the composite coating layer p DO (m+1) / 2 and Li n The molar ratio of F is 1:(0.3-1)b, for example, 1:0.3b, 1:0.4b, 1:0.5b, 1:0.8b, 1:0.85b, 1:0.9b, 1:b, and any value within the range of any two values, preferably 1:(0.8-0.9)b. In this invention, the sintering temperature causes some lithium fluoride to volatilize; if the sintering temperature is too high, a large amount of LiF generated in the reaction will volatilize. Even at low temperatures, some LiF will volatilize. Therefore, within the specific sintering temperature range defined in this invention, a good coating effect can be maintained.

[0046] In this invention, unless otherwise specified, the Li in the composite coating layer... p DO(m+1) / 2 and Li n The method for testing the molar ratio parameter of F is to use XRD to characterize the particles when a certain additive containing doped elements is used for coating, and the ratio can be calculated by the peak area or peak intensity of the two.

[0047] In some embodiments of the present invention, preferably, the additive is selected from nanoscale, as nanoscale additives have a higher contact area, which is more conducive to their reaction with the material surface, thereby generating products that can improve the material properties.

[0048] In some embodiments of the present invention, preferably, the particle size of the additive is 0.01-100 nm, more preferably 20-50 nm; and the specific surface area is ≥150 m². 2 / g, preferably 180-300m 2 / g. In this invention, additives with grain size and specific surface area within the above range have smaller size and larger specific surface area, enabling them to react fully with the surface of high-nickel cathode materials.

[0049] In this invention, unless otherwise specified, the grain size parameter is calculated using the Scherrer formula; the specific surface area parameter is measured using the nitrogen adsorption method.

[0050] In this invention, there is a wide range of choices for the types of additives, as long as the additives satisfy the general formula DF. b Specifically, D is selected from at least one of Mg, Al, Ti, Zr, W, Mo, La, Y, Nb, and Sr, and b is selected from natural numbers from 1 to 5. In other words, the additive provided by this invention is a metal fluoride.

[0051] In some preferred embodiments of the present invention, the additive is preferably selected from at least one of ZrF4, AlF3 and YF3.

[0052] In some embodiments of the present invention, preferably, the amount of the additive relative to 100 parts by weight of the matrix is ​​0.01-10 parts by weight, for example, 0.01 parts by weight, 0.1 parts by weight, 0.2 parts by weight, 0.5 parts by weight, 1 part by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 5 parts by weight, 7 parts by weight, 10 parts by weight, and any value within any range of any two values, preferably 0.1-5 parts by weight, more preferably 0.5-3 parts by weight. If the amount is insufficient, the alkali-reducing effect will be insignificant, and the improvement effect on electrical properties will be poor; if the amount is too high, the capacity utilization of the matrix will be reduced.

[0053] In some embodiments of the present invention, preferably, in the general formula of the matrix, L is selected from Co and / or Mn; M is selected from at least one of Mg, Al, La, Nb and Sr; 0.6≤x≤0.8, for example, x is selected from at least one of 0.6, 0.7, 0.8, and any two of the following values; 0.1≤y≤0.3, for example, y is selected from at least one of 0.1, 0.15, 0.18, 0.2, 0.25, 0.3, and any two of the following values; 0.01≤z≤0.1, for example, z is selected from at least one of 0.01, 0.02, 0.05, 0.08, 0.1, and any two of the following values; a=0.

[0054] In some specific embodiments of the present invention, the matrix has the general formula Li. (1+a) Ni x L y M z O2, wherein L is selected from Co and Mn, M is selected from Mg, Al, and La, 0.6≤x≤0.8, 0.1≤y≤0.3, 0.01≤z≤0.1, and a=0. In this invention, the matrix includes, but is not limited to, LiNi. 0.8 Co 0.1 Mn 0.08 La 0.02 O2, LiNi 0.8 Co 0.1 Mn 0.05 La 0.05 O2, LiNi 0.8 Co 0.1 Mn 0.05 Al 0.05 O2, LiNi 0.7 Co 0.1 Mn 0.15 Mg 0.05 O2, etc.

[0055] In some embodiments of the present invention, preferably, in the composite coating layer, D is selected from at least one of Zr, Al, Y, La and Nb; 1≤p≤2, for example, p is selected from at least one of 1, 1.5, 2, and any two values; 0.99≤n≤1.01, for example, n is selected from at least one of 0.99, 1, 1.01, and any two values; 3≤m≤5, for example, m is selected from 3, 4, 5.

[0056] In some embodiments of the present invention, preferably, the Li nThe molar ratio α of fluorine in F to fluorine in the additive satisfies: 0.3 ≤ α ≤ 1. For example, α is selected from 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.82, 0.85, 0.88, 0.9, 1, and any value within any range of two such values. Preferably, it satisfies: 0.8 ≤ α ≤ 0.9. Using this preferred molar ratio range not only effectively reduces residual lithium on the surface of the high-nickel cathode material but also effectively improves the performance of the modified high-nickel cathode material.

[0057] In this invention, when α < 0.3, preferably α < 0.8, the following situations exist: 1) The sintering temperature is too high, leading to the formation of Li... n 1) A large amount of F volatilizes, resulting in a slight decrease in cycle performance; 2) The sintering temperature is too low, and Li n F did not react sufficiently with the residual lithium on the substrate surface, resulting in poor lithium reduction effect.

[0058] In this invention, when α > 1, preferably α > 0.9, there is an issue of excessive additive dosage, DF b It not only reacts completely with residual lithium on the substrate surface, but also with LiOH and other substances within the substrate. While this effectively reduces residual lithium, it also lowers the lithium content of the substrate, leading to an excess of non-conductive LiOH. n The presence of residual F on the matrix surface reduces the capacity. Therefore, whether α < 0.3 or α > 1, and preferably whether α < 0.8 or α > 0.9, it is detrimental to the overall performance of the material.

[0059] In some embodiments of the present invention, preferably, the residual lithium is selected from lithium hydroxide and / or lithium carbonate, etc. That is, the residual lithium on the substrate surface can be lithium hydroxide or lithium carbonate, or it can be both lithium hydroxide and lithium carbonate.

[0060] In some embodiments of the present invention, preferably, based on the total weight of the substrate, the concentrations of lithium hydroxide and lithium carbonate on the surface of the substrate are set to m1 and m2, respectively, and the concentrations of lithium hydroxide and lithium carbonate on the surface of the modified high-nickel cathode material are set to m3 and m4, respectively, satisfying: Wherein, m1, m2, m3, and m4 are all in ppm, that is, parts per million. When the above conditions are met, the additive is more likely to consume residual lithium on the surface of the matrix and react accordingly, while it is less likely to react with residual lithium (e.g., LiOH) inside the matrix, thus reducing the lithium content of the matrix and consequently the capacity.

[0061] In some embodiments of the present invention, preferably... For example, 6.7%, 9%, 10%, 13%, 15%, 20%, 25%, 30%, 32%, 35%, 40%, 45%, 50%, 55%, 59.5%, and any value within a range of any two values, preferably...

[0062] In some embodiments of the present invention, preferably... For example, 9.8%, 10%, 12%, 15.4%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 68%, 70%, 72.7%, and any value within a range of any two values, are preferred.

[0063] In some embodiments of the present invention, preferably, in the XRD diffraction pattern obtained by the modified high-nickel cathode material under CuKa radiation, 2θ shows obvious diffraction peaks at 38-38.8°, 44.5-45.5°, and 64.8-66°, respectively. When the modified high-nickel cathode material exhibits three strong peaks at the above positions, it indicates that the modified high-nickel cathode material has a good lithium reduction effect.

[0064] In some embodiments of the present invention, preferably, in the XRD diffraction pattern of the modified high-nickel cathode material obtained under CuKa radiation, the ratio β of the peak intensity of the (111) crystal plane to the peak intensity of the (003) crystal plane satisfies: 0.003≤β≤0.02, for example, 0.003, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.012, 0.015, 0.018, 0.02, and any value within the range of any two values, preferably 0.005≤β≤0.015, more preferably 0.006≤β≤0.01. When β satisfies the above conditions, not only is the lithium reduction effect good, but the capacity retention rate is also high. In the present invention, unless otherwise specified, β=1 (111) / I (003) .

[0065] In this invention, when β < 0.003, the alkali reduction effect is not obvious, and the improvement effect on electrical properties is poor; when β > 0.02, although a better alkali reduction effect can be achieved, the capacity utilization of the matrix will be reduced. In this invention, when the sintering temperature is too low or the amount of additive is insufficient, i.e., the sintering temperature is < 400°C or the amount of additive is < 0.01 parts by weight relative to 100 parts by weight of the matrix, then β < 0.003; when the sintering temperature is too high or the amount of additive is too large, i.e., the sintering temperature is > 850°C or the amount of additive is > 10 parts by weight relative to 100 parts by weight of the matrix, then β > 0.02.

[0066] In this invention, when the sintering temperature is 600-750℃, or when the amount of additive is 0.5-3 parts by weight relative to 100 parts by weight of matrix, then 0.006≤β≤0.01, the overall performance of the modified high-nickel cathode material is optimal.

[0067] A second aspect of this invention provides a method for preparing a modified high-nickel cathode material, the method comprising the following steps:

[0068] (1) Provide a general formula Ni γ L δ M ε (OH)2 high nickel precursor, wherein L is selected from at least one of Co, Mn and Al, M is selected from at least one of Mg, Al, Ti, Zr, W, Mo, La, Y, Nb and Sr, γ+δ+ε=1, 0.6≤γ<1, 0.1≤δ≤0.4, 0≤ε≤0.2;

[0069] (2) The high-nickel precursor and lithium source are mixed, and the resulting first mixture is calcined in a first oxygen-containing atmosphere to obtain a product with the general formula Li. (1+a) Ni x L y M z O2 high-nickel cathode material, wherein x+y+z=1, 0.6≤x<1, 0.1≤y≤0.4, 0≤z≤0.2, 0≤a<0.5;

[0070] (3) The high-nickel cathode material and the general formula DF b The additives are mixed, and the resulting second mixture is sintered in a second oxygen-containing atmosphere, allowing the additives to react in situ with residual lithium on the surface of the high-nickel cathode material to form a Li-containing compound on the surface of the high-nickel cathode material. p DO (m+1) / 2 and Li n A composite coating of F is used to obtain a modified high-nickel cathode material;

[0071] Wherein, D is selected from at least one of Mg, Al, Ti, Zr, W, Mo, La, Y, Nb and Sr, 0.95≤p≤2.05, 0.98≤n≤1.02, and m and b are both natural numbers from 1 to 5.

[0072] In this invention, in step (1), the high-nickel precursor is a hydroxy oxide containing Ni, L and M, which is prepared by co-precipitation using water-soluble metal salts as raw materials, thereby solving the problem of uneven metal distribution mentioned above.

[0073] In this invention, the source of the high-nickel precursor has a wide range of selection, as long as the high-nickel precursor satisfies the above general formula. Preferably, in step (1), the high-nickel precursor is obtained by the following method:

[0074] (1-i) Provide a mixed metal salt solution containing Ni source, L source and M source; provide a precipitant solution and a complexing agent solution;

[0075] (1-ii) Under a non-oxidizing atmosphere, the mixed metal salt solution, precipitant solution and complexing agent solution are mixed and co-precipitated. The resulting precursor slurry is then filtered, washed and dried to obtain the high-nickel precursor.

[0076] In some embodiments of the present invention, preferably, in step (1-i), in the general formula of the high-nickel precursor, L is selected from Co and / or Mn, M is selected from at least one of Mg, La, Al, Nb and Sr, γ+δ+ε=1, 0.6≤γ≤0.8, for example, γ is selected from at least one of 0.6, 0.7, 0.8, and any two of the following values; 0.1≤δ≤0.3, for example, δ is selected from at least one of 0.1, 0.15, 0.18, 0.2, 0.25, 0.3, and any two of the following values; 0.01≤ε≤0.1, for example, ε is selected from at least one of 0.01, 0.02, 0.05, 0.08, 0.1, and any two of the following values.

[0077] In some specific embodiments of the present invention, in step (1-i), the general formula of the high-nickel precursor is Ni. γ L δ M ε (OH)₂, wherein L is selected from Co and Mn, M is selected from Mg, Al, and La, 0.6 ≤ γ ≤ 0.8, 0.1 ≤ δ ≤ 0.3, and 0.01 ≤ ε ≤ 0.1. In this invention, the high-nickel precursor includes, but is not limited to, Ni. 0.8 Co 0.1 Mn 0.08 La 0.02 (OH)2, Ni 0.8 Co 0.1 Mn 0.05 La 0.05 (OH)2, Ni 0.8 Co 0.1 Mn 0.05 Al 0.05 (OH)2, Ni 0.7 Co 0.1 Mn 0.15 Mg 0.05 (OH)2, etc.

[0078] In some embodiments of the present invention, preferably, in step (1-i), the Ni source calculated in Ni, the L source calculated in L, and the M source calculated in M ​​satisfy: n(Ni):n(L):n(M), where 0.6≤n(Ni)<1, 0.1≤0.6≤0.4, 0≤n(M)≤0.2; more preferably, 0.6≤n(Ni)≤0.8, 0.1≤n(L)≤0.3, 0.01≤n(M)≤0.1.

[0079] In some embodiments of the present invention, preferably, the Ni source, L source and M source are each independently selected from at least one of sulfates, nitrates, chlorates and acetates containing Ni, L and M.

[0080] In some specific embodiments of the present invention, the Ni source is selected from at least one of nickel sulfate, nickel nitrate, nickel chlorate, and nickel acetate.

[0081] In some specific embodiments of the present invention, the L source is selected from at least one of sulfates, nitrates, chlorates, and acetates containing Co, Mn, and Al, preferably from at least one of sulfates, nitrates, chlorates, and acetates containing Co and / or Mn, and more preferably from at least one of sulfates, nitrates, chlorates, and acetates containing Co and Mn. In the present invention, the L source includes, but is not limited to, cobalt sulfate, cobalt nitrate, cobalt chlorate, cobalt acetate, manganese sulfate, manganese nitrate, manganese chlorate, and manganese acetate.

[0082] In some specific embodiments of the present invention, the M source is selected from at least one of sulfates, nitrates, chlorates, and acetates containing Mg, Al, Ti, Zr, W, Mo, La, Y, Nb, and Sr, preferably from at least one of sulfates, nitrates, chlorates, and acetates containing Mg, Al, La, Nb, and Sr, and more preferably from at least one of sulfates, nitrates, chlorates, and acetates containing Mg, Al, and La. In the present invention, the M source includes, but is not limited to, magnesium sulfate, manganese nitrate, aluminum nitrate, zirconium sulfate, zirconium nitrate, lanthanum nitrate, strontium sulfate, etc.

[0083] In some embodiments of the present invention, preferably, the concentration of total metal ions in the mixed metal salt solution is 0.1-5 mol / L, for example, 0.1 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, or any value within a range of any two values. The concentration of total metal ions is the sum of the concentrations of Ni ions in the Ni source, L ions in the L source, and M ions in the M source.

[0084] In some embodiments of the present invention, preferably, the concentration of the precipitant in the precipitant solution is 1-10 mol / L, for example, 1 mol / L, 2 mol / L, 5 mol / L, 8 mol / L, 10 mol / L, or any value within a range of any two values. In the present invention, the precipitant in the precipitant solution is selected from sodium hydroxide and / or potassium hydroxide.

[0085] In some embodiments of the present invention, preferably, the concentration of the complexing agent in the complexing agent solution is 0.5-5 mol / L, for example, 0.5 mol / L, 0.8 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, or any value within any range of two such values. In the present invention, the complexing agent in the complexing agent solution is selected from at least one of ammonia, disodium ethylenediaminetetraacetate, ammonium nitrate, ammonium chloride, and ammonium sulfate.

[0086] In some embodiments of the present invention, the mixed metal salt solution, precipitant solution, and complexing agent solution are introduced into the reactor in a co-precipitation reaction in a parallel flow manner.

[0087] In this invention, particle growth is controlled by adjusting the pH, temperature, and time of the co-precipitation reaction to obtain a high-nickel precursor with uniform size. Preferably, in step (1-ii), the conditions for the co-precipitation reaction include: pH 10-12; temperature 50-80°C; and time 5-20 h. In this invention, the pH of the co-precipitation reaction is controlled to be 10-12 (the pH error can be ±0.5) by controlling the addition rate of the complexing agent solution.

[0088] In some embodiments of the present invention, preferably, in step (1-ii), the non-oxidizing atmosphere is selected from at least one of nitrogen, helium, argon and neon; more preferably, the non-oxidizing atmosphere is selected from nitrogen.

[0089] In this invention, the filtration method in step (1-ii) has a wide range of options. As long as the precursor slurry is subjected to solid-liquid separation, it can be a prior art known to those skilled in the art, such as positive pressure filtration, negative pressure filtration, centrifugation, vacuum filtration, etc., to obtain the filtration product.

[0090] In some embodiments of the present invention, the washing method is not particularly limited, and conventional washing methods in the art are applicable to the present invention. Preferably, the filtered product is washed with water to remove residual slurry from the filtered product, resulting in a washed product.

[0091] In some embodiments of the present invention, preferably, the drying conditions include: a temperature of 110-130°C, more preferably 115-125°C; and a time of 5-10 hours, more preferably 6-9 hours.

[0092] In some embodiments of the present invention, preferably, in step (2), the molar ratio of the high-nickel precursor (calculated as Ni) to the lithium source (calculated as Li) satisfies: n(Ni):n(Li), where 0.6≤n(Ni)<1, 1≤n(Li)<1.5; more preferably, 0.6≤n(Ni)≤0.8, n(Li)=1.

[0093] In this invention, a wide range of lithium sources can be selected. Preferably, the lithium source is selected from lithium-containing compounds, more preferably from at least one of lithium oxide, lithium hydroxide, lithium chloride, lithium nitrate, lithium nitrite, lithium formate, lithium acetate, lithium oxalate, lithium carbonate, lithium phosphate, dilithium hydrogen phosphate, lithium dihydrogen phosphate, and lithium citrate, and more preferably from at least one of lithium carbonate, lithium hydroxide, and lithium chloride.

[0094] In some embodiments of the present invention, preferably, the calcination conditions include: a temperature of 700-1000℃, for example, 700℃, 800℃, 850℃, 900℃, 1000℃, and any value within the range of any two values, preferably 800-900℃; and a time of 5-20h, for example, 5h, 6h, 8h, 10h, 12h, 15h, 20h, and any value within the range of any two values, preferably 6-12h.

[0095] In some embodiments of the present invention, preferably, the oxygen content in the first oxygen-containing atmosphere is 20-100% by volume, for example, 20%, 50%, 80%, 100%, or any value within a range of any two of these values. In the present invention, the first oxygen-containing atmosphere includes, but is not limited to, an oxygen atmosphere, air, etc.

[0096] In some embodiments of the present invention, preferably, in step (2), in the general formula of the high-nickel cathode material, L is selected from Co and / or Mn, M is selected from at least one of Mg, La, Al, Nb and Sr, 0.6≤x≤0.8, for example, x is selected from at least one of 0.6, 0.7, 0.8, and any two of the above values; 0.1≤y≤0.3, for example, y is selected from at least one of 0.1, 0.15, 0.18, 0.2, 0.25, 0.3, and any two of the above values; 0.01≤z≤0.1, for example, z is selected from at least one of 0.01, 0.02, 0.05, 0.08, 0.1, and any two of the above values; a=0.

[0097] In some specific embodiments of the present invention, the high-nickel cathode material has the general formula Li. (1+a) Ni x L y M z O2, wherein L is selected from Co and Mn, M is selected from Mg, Al, and La, 0.6≤x≤0.8, 0.1≤y≤0.3, 0.01≤z≤0.1, and a=0. In this invention, the matrix includes, but is not limited to, LiNi. 0.8 Co 0.1 Mn 0.08 La 0.02 O2, LiNi 0.8 Co 0.1 Mn 0.05 La 0.05 O2, LiNi 0.8 Co 0.1 Mn 0.05 La 0.05 O2, LiNi 0.7 Co 0.1 Mn 0.15 Mg 0.05 O2, etc.

[0098] In some embodiments of the present invention, preferably, in step (3), in the general formula of the additive, D is selected from at least one of Zr, Al, Y, La and Nb, and b is selected from natural numbers from 3 to 5; more preferably, D is selected from Zr, Al, Y, and b is selected from natural numbers from 3 to 4.

[0099] In some specific embodiments of the present invention, the additives include, but are not limited to, ZrF4, AlF3 and YF3.

[0100] In some embodiments of the present invention, preferably, in step (3), the weight ratio of the high-nickel cathode material to the additive is 100:0.01-10, for example, 100:0.01, 100:0.1, 100:0.2, 100:0.5, 100:1, 100:1.5, 100:2, 100:2.5, 100:3, 100:5, 100:7, 100:10, and any value within any range of any two values, preferably 100:0.1-5, preferably 100:0.5-3. Using the preferred protection range not only results in good lithium reduction but also high capacity retention.

[0101] In some embodiments of the present invention, preferably, in step (3), the sintering conditions include: a temperature of 400-850℃, for example, 400℃, 600℃, 650℃, 700℃, 730℃, 750℃, 800℃, 850℃, and any value within the range of any two values, preferably 600-750℃; and a time of 5-10h, for example, 5h, 6h, 7h, 8h, 10h, 15h, 20h, and any value within the range of any two values, preferably 5-8h. Using sintering temperatures within the above range can effectively balance the lithium reduction effect and capacity retention; if the sintering temperature is >850℃, it will lead to the formation of Li... n A significant amount of F volatilizes, resulting in a slight decrease in cycle performance; if the sintering temperature is <400℃, then Li n F cannot fully react with the residual lithium on the substrate surface, resulting in poor lithium reduction effect.

[0102] In some embodiments of the present invention, preferably, in step (3), the residual lithium is selected from lithium hydroxide and / or lithium carbonate.

[0103] In some embodiments of the present invention, preferably, in step (3), the oxygen content in the second oxygen-containing atmosphere is 20-100% by volume, for example, 20%, 50%, 80%, 100%, and any value within a range of any two values. In the present invention, the second oxygen-containing atmosphere includes, but is not limited to, air atmosphere, oxygen atmosphere, etc.

[0104] In this invention, unless otherwise specified, the composite coating layer, i.e., Li p DO (m+1) / 2 and Li n F, given by the general formula DF b It is prepared by in-situ reaction of additives and residual lithium (i.e., lithium hydroxide, lithium carbonate) on the surface of the positive electrode material.

[0105] In one specific embodiment of the present invention, when the additive is selected from ZrF4, the composite coating layer is Li2ZrO3 and LiF; when the additive is selected from AlF3, the composite coating layer is Li2AlO3 and LiF; when the additive is selected from YF3, the composite coating layer is LiYO2 and LiF.

[0106] The third aspect of this invention provides a modified high-nickel cathode material provided in the first aspect, or the modified high-nickel cathode material prepared by the preparation method provided in the second aspect, for use in lithium-ion batteries.

[0107] The fourth aspect of the present invention provides a lithium-ion battery, wherein the lithium-ion battery contains a modified high-nickel cathode material provided in the first aspect, or a modified high-nickel cathode material prepared by the preparation method provided in the second aspect.

[0108] In one specific embodiment of the present invention, the lithium-ion battery includes an electrode assembly and an electrolyte, the electrode assembly and the electrolyte are sealed in a battery casing, the electrode assembly includes a positive electrode, a negative electrode and a separator, the separator is located between the positive electrode and the negative electrode, and the positive electrode contains a modified high-nickel positive electrode material provided by the present invention.

[0109] The present invention will be described in detail below through embodiments.

[0110] XRD is used to obtain information such as the composition of materials and the structure or morphology of atoms or molecules inside the materials. The XRD diffractometer used is an XRD-6000 X-ray powder diffractometer (Shimadzu, Japan). The XRD test conditions are: Cu target, Kα rays (wavelength λ = 0.154 nm), tube voltage of 40 kV, tube current of 200 mA, and scanning speed of 10° (2θ) / min.

[0111] In the expressions for the high-nickel precursor and the cathode material, the elements and their contents were obtained by inductively coupled plasma spectrometry (ICP) using a PerkinElmer PE-7000DV instrument purchased from PerkinElmer Instruments Ltd.

[0112] Preparation Examples 1-4 were used to prepare high-nickel precursors Z1-Z4.

[0113] Preparation Example 1

[0114] (1-i) Nickel sulfate, cobalt sulfate, manganese sulfate, and lanthanum nitrate (all calculated as metal elements) were dissolved in water in a molar ratio of 80:10:8:2 to obtain 50 L of a mixed metal salt solution with a total metal ion concentration of 2 mol / L; sodium hydroxide was dissolved in water as a precipitant to obtain a precipitant solution with a concentration of 5 mol / L; ammonia was dissolved in water as a complexing agent to obtain a complexing agent solution with a concentration of 2 mol / L.

[0115] (1-ii) Under a nitrogen atmosphere, the above-mentioned mixed metal salt solution, precipitant solution, and complexing agent solution were introduced into the reactor in parallel at flow rates of 4 L / h, 1.5 L / h, and 100 mL / h, respectively, for co-precipitation reaction. The reaction temperature was controlled at 60 °C, the pH at 11.5, and the reaction time at 5 h. The resulting precursor slurry was subjected to solid-liquid separation and washing by centrifugation. The filter cake was dried at 120 °C for 6 h to obtain Ni 0.8 Co 0.1 Mn 0.08 La 0.02 Z1, a high-nickel precursor of (OH)2.

[0116] Preparation Example 2

[0117] (1-i) Nickel sulfate, cobalt sulfate, manganese sulfate, and lanthanum nitrate (all calculated as metal elements) were dissolved in water in a molar ratio of 80:10:5:5 to obtain 100 L of a mixed metal salt solution with a total metal ion concentration of 4 mol / L; sodium hydroxide was dissolved in water as a precipitant to obtain a precipitant solution with a concentration of 8 mol / L; ammonia was dissolved in water as a complexing agent to obtain a complexing agent solution with a concentration of 0.8 mol / L.

[0118] (1-ii) Under a nitrogen atmosphere, the above-mentioned mixed metal salt solution, precipitant solution, and complexing agent solution were introduced into the reactor in parallel at flow rates of 4 L / h, 2 L / h, and 150 mL / h, respectively, for co-precipitation reaction. The reaction temperature was controlled at 50 °C, pH at 12, and the reaction time at 5 h. The resulting precursor slurry was subjected to solid-liquid separation and washing by centrifugation. The filter cake was dried at 120 °C for 6 h to obtain Ni 0.8 Co 0.1 Mn 0.05 La 0.05 Z2, a high-nickel precursor of (OH)2.

[0119] Preparation Example 3

[0120] (1-i) Nickel sulfate, cobalt sulfate, manganese sulfate, and aluminum nitrate (all calculated as metal elements) were dissolved in water in a molar ratio of 80:10:5:5 to obtain 100 L of a mixed metal salt solution with a total metal ion concentration of 4 mol / L; sodium hydroxide was dissolved in water as a precipitant to obtain a precipitant solution with a concentration of 8 mol / L; ammonia was dissolved in water as a complexing agent to obtain a complexing agent solution with a concentration of 1.0 mol / L.

[0121] (1-ii) Under a nitrogen atmosphere, the above-mentioned mixed metal salt solution, precipitant solution, and complexing agent solution were introduced into the reactor in parallel at flow rates of 5 L / h, 2 L / h, and 150 mL / h, respectively, for co-precipitation reaction. The reaction temperature was controlled at 50 °C, pH at 12, and the reaction time at 5 h. The resulting precursor slurry was subjected to solid-liquid separation and washing by centrifugation. The filter cake was dried at 120 °C for 6 h to obtain Ni 0.8 Co 0.1 Mn 0.05 Al 0.05 Z3, a high-nickel precursor of (OH)2.

[0122] Preparation Example 4

[0123] (1-i) Nickel sulfate, cobalt sulfate, manganese sulfate, and magnesium nitrate (all calculated as metal elements) were dissolved in water in a molar ratio of 70:10:15:5 to obtain 100 L of a mixed metal salt solution with a total metal ion concentration of 2 mol / L; sodium hydroxide was dissolved in water as a precipitant to obtain a precipitant solution with a concentration of 5 mol / L; ammonia was dissolved in water as a complexing agent to obtain a complexing agent solution with a concentration of 1.0 mol / L.

[0124] (1-ii) Under a nitrogen atmosphere, the above-mentioned mixed metal salt solution, precipitant solution, and complexing agent solution were introduced into the reactor in parallel at flow rates of 4.5 L / j, 1.8 L / h, and 150 mL / h, respectively, for co-precipitation reaction. The reaction temperature was controlled at 65 °C, pH at 11, and the reaction time at 5 h. The resulting precursor slurry was subjected to solid-liquid separation and washing by centrifugation. The filter cake was dried at 120 °C for 6 h to obtain Ni 0.7 Co 0.1 Mn 0.15 Mg 0.05 Z4, a high-nickel precursor of (OH)2.

[0125] As can be seen from the preparation examples 1-4, the present invention uses wet precipitation to uniformly distribute the dopant element (i.e., the M source) inside the high-nickel precursor, obtaining the general formula Ni. γ L δ M ε The high-nickel precursor of (OH)2, wherein L is selected from at least one of Co, Mn and Al, M is selected from at least one of Mg, Al, Ti, Zr, W, Mo, La, Y, Nb and Sr, γ+δ+ε=1, 0.6≤γ<1, 0.1≤δ≤0.4, 0≤ε≤0.2, is more conducive to the stability of the internal structure of the material, thereby improving the electrical performance of the modified high-nickel cathode material.

[0126] Examples 1-12 and Comparative Examples 1-2 were used to prepare modified high-nickel cathode materials (S1-S12 and DS1-DS2).

[0127] Example 1

[0128] (1) The general formula Ni provided in Preparation Example 1 was used. 0.8 Co 0.1 Mn 0.08 L 0.02 Z1, a high-nickel precursor of (OH)2;

[0129] (2) In an oxygen atmosphere, the above-mentioned high-nickel precursor Z1 (calculated as Ni) and lithium hydroxide (calculated as Li) were mixed at a molar ratio of 0.8:1. The first mixture was sintered at 800°C for 10 h, and then subjected to natural cooling, crushing, and sieving to obtain the general formula LiNi. 0.8 Co 0.1 Mn0.08 La 0.02 O2 high-nickel cathode material Q1;

[0130] (3) In an air atmosphere, 10 kg of the above-mentioned high-nickel cathode material Q1 and 0.02 kg of additive (nano-sized ZrF4, with a grain size of 20 nm and a specific surface area of ​​210 m²) are placed together. 2 The mixture of / g) is sintered at 730°C for 6 hours to allow the additive to react in situ with the residual lithium on the surface of the high-nickel cathode material Q1, thereby forming a composite coating layer containing Li2ZrO3 and LiF on the surface of the high-nickel cathode material Q1, thus obtaining the modified high-nickel cathode material S1.

[0131] The composition and process parameters of the modified high-nickel cathode material S1 are listed in Table 1, and the physical properties of the modified high-nickel cathode material S1 are listed in Table 2.

[0132] The XRD pattern of the modified high-nickel cathode material S1 is shown below. Figure 1 As shown, by Figure 1 It can be seen that 2θ has three strong characteristic peaks of Li2ZrO3 at 20.3° / 26.6° / 42.5°, and three strong characteristic peaks of LiF at 38.7° / 45° / 65°. However, the modified high-nickel cathode material S1 does not have obvious characteristic peaks of Li2ZrO3 and LiF, mainly because the amount of additives used is low.

[0133] Example 2

[0134] The method is the same as in Example 1, except that...

[0135] In step (3), the amount of additive used is replaced with 0.05 kg.

[0136] Under the same conditions, a composite coating layer containing Li2ZrO3 and LiF is formed on the surface of the above-mentioned high-nickel cathode material Q1 to obtain the modified high-nickel cathode material S2.

[0137] The composition and process parameters of the modified high-nickel cathode material S2 are listed in Table 1, and the physical properties of the modified high-nickel cathode material S2 are listed in Table 2.

[0138] Example 3

[0139] The method is the same as in Example 1, except that...

[0140] In step (3), the amount of additive is replaced with 0.15 kg.

[0141] Under the same conditions, a composite coating layer containing Li2ZrO3 and LiF was formed on the surface of the above-mentioned high-nickel cathode material Q1 to obtain the modified high-nickel cathode material S3.

[0142] The composition and process parameters of the modified high-nickel cathode material S3 are listed in Table 1, and the physical properties of the modified high-nickel cathode material S3 are listed in Table 2.

[0143] The XRD pattern of the modified high-nickel cathode material S3 is shown below. Figure 1 As shown, by Figure 1 It can be seen that, with the increase of additive dosage, compared with modified high-nickel cathode material S1, modified high-nickel cathode material S3 has obvious characteristic peaks of Li2ZrO3 and LiF on its surface.

[0144] Example 4

[0145] The method is the same as in Example 1, except that...

[0146] In step (3), the amount of additive is replaced with 0.3 kg.

[0147] Under the same conditions, a composite coating layer containing Li2ZrO3 and LiF was formed on the surface of the above-mentioned high-nickel cathode material Q1 to obtain the modified high-nickel cathode material S4.

[0148] The composition and process parameters of the modified high-nickel cathode material S4 are listed in Table 1, and the physical properties of the modified high-nickel cathode material S4 are listed in Table 2.

[0149] The SEM image of the S4 cross-section of the aforementioned modified high-nickel cathode material is shown below. Figure 2 As shown, by Figure 2 It can be seen that the modified high-nickel cathode material S4 profile has a clear interface between the matrix and the composite coating layer, wherein the thickness of the composite coating layer is 23.47 nm.

[0150] Example 5

[0151] The method is the same as in Example 1, except that...

[0152] In step (3), the amount of additive is replaced with 0.5 kg.

[0153] Under the same conditions, a composite coating layer containing Li2ZrO3 and LiF is formed on the surface of the above-mentioned high-nickel cathode material Q1 to obtain the modified high-nickel cathode material S5.

[0154] The composition and process parameters of the modified high-nickel cathode material S5 are listed in Table 1, and the physical properties of the modified high-nickel cathode material S5 are listed in Table 2.

[0155] Example 6

[0156] The method is the same as in Example 1, except that...

[0157] In step (3), the amount of additive used is replaced with 0.7 kg.

[0158] Under the same conditions, a composite coating layer containing Li2ZrO3 and LiF was formed on the surface of the above-mentioned high-nickel cathode material Q1 to obtain the modified high-nickel cathode material S6.

[0159] The composition and process parameters of the modified high-nickel cathode material S6 are listed in Table 1, and the physical properties of the modified high-nickel cathode material S6 are listed in Table 2.

[0160] The XRD pattern of the modified high-nickel cathode material S6 is shown below. Figure 1 As shown, by Figure 1 It can be seen that, with the increase of additive dosage, compared with modified high-nickel cathode material S1, modified high-nickel cathode material S6 has obvious characteristic peaks of Li2ZrO3 and LiF on its surface.

[0161] Example 7

[0162] The method is the same as in Example 3, except that...

[0163] In step (3), the sintering temperature is replaced with 850℃.

[0164] Under the same conditions, a composite coating layer containing Li2ZrO3 and LiF was formed on the surface of the above-mentioned high-nickel cathode material Q1 to obtain the modified high-nickel cathode material S7.

[0165] The composition and process parameters of the modified high-nickel cathode material S7 are listed in Table 1, and the physical properties of the modified high-nickel cathode material S7 are listed in Table 2.

[0166] Example 8

[0167] The method is the same as in Example 3, except that...

[0168] In step (3), the sintering temperature is replaced with 400℃.

[0169] Under the same conditions, a composite coating layer containing Li2ZrO3 and LiF was formed on the surface of the above-mentioned high-nickel cathode material Q1 to obtain the modified high-nickel cathode material S8.

[0170] The composition and process parameters of the modified high-nickel cathode material S8 are listed in Table 1, and the physical properties of the modified high-nickel cathode material S8 are listed in Table 2.

[0171] Example 9

[0172] The method is the same as in Example 3, except that...

[0173] In step (3), the additive ZrF4 is non-nano-sized.

[0174] Under the same conditions, a composite coating layer containing Li2ZrO3 and LiF was formed on the surface of the above-mentioned high-nickel cathode material Q1 to obtain the modified high-nickel cathode material S9.

[0175] The composition and process parameters of the modified high-nickel cathode material S9 are listed in Table 1, and the physical properties of the modified high-nickel cathode material S9 are listed in Table 2.

[0176] Example 10

[0177] (1) The general formula Ni provided in Preparation Example 2 was used. 0.8 Co 0.1 Mn 0.05 La 0.05 Z2, a high-nickel precursor of (OH)2;

[0178] (2) In an oxygen atmosphere, the above-mentioned high-nickel precursor Z2 (calculated as Ni) and lithium hydroxide (calculated as Li) were mixed at a molar ratio of 0.8:1. The first mixture was sintered at 850°C for 10 h, and then subjected to natural cooling, crushing, and sieving to obtain the general formula LiNi. 0.8 Co 0.1 Mn 0.05 La 0.05 Q2, a high-nickel cathode material containing O2;

[0179] (3) In an air atmosphere, 10 kg of the above-mentioned high-nickel cathode material Q2 and 0.1 kg of additive (nano-sized AlF3, with a grain size of 25 nm and a specific surface area of ​​257 m²) are placed together. 2 The mixture of / g) is sintered at 700°C for 9 hours to allow the additive to react in situ with the residual lithium on the surface of the high-nickel cathode material Q2, thereby forming a composite coating layer containing Li2AlO3 and LiF on the surface of the high-nickel cathode material Q2, and obtaining the modified high-nickel cathode material S10.

[0180] The composition and process parameters of the modified high-nickel cathode material S10 are listed in Table 1, and the physical properties of the modified high-nickel cathode material S10 are listed in Table 2.

[0181] Example 11

[0182] (1) The general formula Ni provided in Preparation Example 3 was used. 0.8 Co 0.1 Mn 0.05 Al 0.05 Z3, a high-nickel precursor of (OH)2;

[0183] (2) In an oxygen atmosphere, the above-mentioned high-nickel precursor Z3 (calculated as Ni) and lithium hydroxide (calculated as Li) were mixed at a molar ratio of 0.8:1. The resulting first mixture was sintered at 850°C for 10 hours, and then subjected to natural cooling, crushing, and sieving to obtain the general formula LiNi. 0.8 Co 0.1 Mn 0.05 Al 0.05 Q3, a high-nickel cathode material with O2;

[0184] (3) In an air atmosphere, 10 kg of the above-mentioned high-nickel cathode material Q3 and 0.1 kg of additive (nano-sized YF3, with a grain size of 30 nm and a specific surface area of ​​201 m²) are placed together. 2 The mixture of / g) was sintered at 780°C for 9 hours to allow the additive to react in situ with the residual lithium on the surface of the high-nickel cathode material Q3, thereby forming a composite coating layer containing LiYO2 and LiF on the surface of the high-nickel cathode material Q3, thus obtaining the modified high-nickel cathode material S11.

[0185] The composition and process parameters of the modified high-nickel cathode material S11 are listed in Table 1, and the physical properties of the modified high-nickel cathode material S11 are listed in Table 2.

[0186] Example 12

[0187] (1) The general formula Ni provided in Preparation Example 4 was adopted. 0.7 Co 0.1 Mn 0.15 Mg 0.05 Z4, a high-nickel precursor of (OH)2;

[0188] (2) In an oxygen atmosphere, the above-mentioned high-nickel precursor Z4 (calculated as Ni) and lithium hydroxide (calculated as Li) were mixed at a molar ratio of 0.7:1. The first mixture was sintered at 850°C for 10 h, and then subjected to natural cooling, crushing, and sieving to obtain the general formula LiNi. 0.7 Co 0.1 Mn 0.15 Mg 0.05 O2 high-nickel cathode material Q4;

[0189] (3) In an air atmosphere, 10 kg of the above-mentioned high-nickel cathode material Q4 and 0.1 kg of additive (nano-sized AlF3, with a grain size of 15 nm and a specific surface area of ​​298 m²) are placed together. 2 The mixture of / g) is sintered at 850°C for 9 hours to allow the additive to react in situ with the residual lithium on the surface of the high-nickel cathode material Q4, thereby forming a composite coating layer containing LiAlO2 and LiF on the surface of the high-nickel cathode material Q4, thus obtaining the modified high-nickel cathode material S12.

[0190] The composition and process parameters of the modified high-nickel cathode material S12 are listed in Table 1, and the physical properties of the modified high-nickel cathode material S12 are listed in Table 2.

[0191] Comparative Example 1

[0192] The method is the same as in Example 1, except that step (3) is omitted, i.e.

[0193] In an air atmosphere, 10 kg of the above-mentioned high-nickel cathode material Q1 was directly sintered at 730℃ for 6 hours. After crushing and sieving, a secondary sintered material with the general formula LinI was obtained. 0.8 Co 0.1 Mn 0.08 Ka 0.02 DS1, a high-nickel cathode material modified with O2.

[0194] The composition and process parameters of the modified high-nickel cathode material DS1 are listed in Table 1, and the physical properties of the modified high-nickel cathode material DS1 are listed in Table 2.

[0195] Comparative Example 2

[0196] The method is the same as in Example 1, except that in step (3), the additive is selected from organofluorine compounds, i.e.,

[0197] In an air atmosphere, 10 kg of the above high-nickel cathode material Q1 and 0.2 kg of additive (PVDF) were mixed, and the resulting second mixture was sintered at 300°C for 2 h, so that the additive reacted in situ with the residual lithium on the surface of the above high-nickel cathode material Q1 to form a coating layer containing LiF on the surface of the above high-nickel cathode material Q1, thereby obtaining the modified high-nickel cathode material DS2.

[0198] The composition and process parameters of the modified high-nickel cathode material DS2 are listed in Table 1, and the physical properties of the modified high-nickel cathode material DS2 are listed in Table 2.

[0199] Table 1

[0200]

[0201] Continued from Table 1

[0202]

[0203]

[0204] Note: 1 - refers to the weight ratio of high-nickel cathode material and additives; 2 - Li in the composite coating layer p DO (m+1) / 2 and Li n The molar ratio of F.

[0205] As shown in Table 1, compared to Comparative Examples 1-2, the modified high-nickel cathode materials prepared using the methods provided in Examples 1-12 include those with the general formula Li. (1+a) Ni x L y M z The matrix of O2 and the composite coating layer, wherein the composite coating layer is Li p DO (m+1) / 2 and Li n F. In particular, by controlling the amount of additives and sintering conditions, the content and thickness of the composite coating layer of the modified high-nickel cathode material, as well as the Li content in the composite coating layer, can be further controlled. p DO (m+1) / 2 and Li n The molar ratio of F.

[0206] Table 2

[0207]

[0208] Note: α-Li n The molar ratio of fluorine in F to fluorine in the additive; β-I (111) / I (003) That is, the ratio of the peak intensity of the (111) crystal plane to the peak intensity of the (003) crystal plane in the XRD diffraction pattern of the modified high-nickel cathode material under CuKa radiation.

[0209] Continued from Table 2

[0210]

[0211] Note:

[0212] As can be seen from the data in Table 2, compared with Comparative Examples 1-2, the dry treatment method used in Examples 1-12 resulted in a significant reduction in residual lithium and pH value on the surface of the modified high-nickel cathode material.

[0213] Comparing the data from Examples 1-6, it can be seen that as the amount of additives increases, the residual lithium on the surface of the modified high-nickel cathode material continues to decrease, indicating that the additives not only react with the residual lithium on the substrate surface, but also react with the lithium hydroxide inside the substrate, thereby consuming too much residual lithium on the surface; at the same time, the ratio β of the LiF characteristic peak (111) to the high-nickel multi-element characteristic peak (003) gradually increases.

[0214] Compared to Examples 1 and 8, Example 9 showed better lithium reduction performance. This was mainly because the amount of additive used in Example 1 was relatively low, resulting in an insignificant effect on removing residual lithium. Example 8 involved low-temperature treatment (i.e., a low sintering temperature), which meant that the additive participated in the reaction very little, thus also resulting in poor performance. Although Example 9 used non-nano additives, the impact was smaller compared to the amount of additive and the sintering temperature. However, compared to Example 3, it still suffered from insufficient reaction, leading to poor performance.

[0215] Test case

[0216] The modified high-nickel cathode materials (S1-S12 and DS1-DS2) prepared in Examples 1-12 and Comparative Examples 1-2 were assembled into coin cells for electrochemical performance testing. The test results are listed in Table 3.

[0217] Prepare a coin cell according to the following steps:

[0218] 9.2g of positive electrode material, 0.4g of acetylene black and 0.4g of polyvinylidene fluoride (PVDF) were mixed, coated on aluminum foil and dried. The mixture was then stamped with a pressure of 100MPa to obtain a positive electrode sheet with a diameter of 12mm and a thickness of 120μm. The positive electrode sheet was then placed in a vacuum drying oven and dried at 120℃ for 12h.

[0219] The negative electrode uses a Li metal sheet with a diameter of 17 mm and a thickness of 1 mm; the separator uses a polyethylene porous membrane with a thickness of 25 μm; the electrolyte uses an equal mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) with 1 mol / L LiPF6 as the electrolyte.

[0220] The positive electrode, separator, negative electrode, and electrolyte are assembled into a 2025 type button cell in an Ar gas glove box with a water content and oxygen content of less than 5 ppm.

[0221] The cycling performance of the coin cells assembled from the modified high-nickel cathode materials provided in Examples 1-9 and Comparative Examples 1-2 at 45°C and 1C rate is shown in the figure below. Figure 3 As shown.

[0222] Depend on Figure 3 It can be seen that in Example 7, the high secondary calcination temperature caused a large amount of LiF generated in the reaction to volatilize, resulting in a slight decrease in cycle performance.

[0223] Example 8 mainly suffers from an excessively low secondary firing temperature, which results in the surface additives not reacting completely and failing to achieve the expected effect.

[0224] Compared to Example 3, Example 9 uses non-nano additives, which are less likely to react with the material surface under the same treatment conditions due to their lower activity.

[0225] Comparative Example 1 showed no significant improvement in lithium reduction and capacity cycling after direct secondary sintering without any treatment.

[0226] Comparative Example 2 uses PVDF as an additive for comparison. Under low-temperature sintering treatment, the modification effect on the material is not obvious, which may be due to the large amount of PVDF volatilization caused by the second sintering, resulting in the failure to generate LiF.

[0227] Table 3

[0228]

[0229] As shown in Table 3, compared with Comparative Examples 1-2, the coin cells assembled from the modified high-nickel cathode materials prepared in Examples 1-12 have higher electrochemical performance, especially better rate performance.

[0230] Comparing Examples 1-6, it can be seen that as the amount of additive increases, the half-cell capacity and initial efficiency first increase and then decrease. This is mainly because the amount of additive is too high, so some additives do not participate in the reaction with the residual lithium on the surface, resulting in a low capacity. When the amount of additive reaches a certain level, the high-temperature cycling no longer improves the capacity, and further increasing the amount does not result in a significant change.

[0231] 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 modified high-nickel cathode material, characterized in that, It includes a matrix and a composite coating layer loaded on the matrix, wherein the matrix has the general formula Li (1+a) Ni x L y M z O2, L is selected from at least one of Co, Mn and Al, M is selected from at least one of Mg, Al, Ti, Zr, W, Mo, La, Y, Nb and Sr, x+y+z=1, 0.6≤x<1, 0.1≤y≤0.4, 0.01≤z≤0.2, 0≤a<0.5; The composite coating layer contains residual lithium from the substrate surface and a general formula DF. b Li generated in situ by additives p DO (m+1) / 2 and Li n F, Li p DO (m+1) / 2 and Li n The molar ratio of F is 1:(0.8-1)b, D is selected from at least one of Mg, Al, Ti, Zr, W, Mo, La, Y, Nb and Sr, 0.95≤p≤2.05, 0.98≤n≤1.02, and m and b are both natural numbers from 1 to 5.

2. The modified high-nickel cathode material according to claim 1, wherein, Based on the total weight of the modified high-nickel cathode material, the content of the matrix is ​​90-99.9 wt%, and the content of the composite coating layer is 0.1-10 wt%. And / or, the thickness of the composite coating layer is 1-50 nm; And / or, the Li in the composite coating layer p DO (m+1) / 2 and Li n The molar ratio of F is 1:(0.8-0.9)b.

3. The modified high-nickel cathode material according to claim 2, wherein, Based on the total weight of the modified high-nickel cathode material, the content of the matrix is ​​95-98.5 wt%, and the content of the composite coating layer is 0.2-5 wt%. And / or, the thickness of the composite coating layer is 5-30 nm.

4. The modified high-nickel cathode material according to claim 3, wherein, Based on the total weight of the modified high-nickel cathode material, the content of the matrix is ​​97-99.5 wt%, and the content of the composite coating layer is 0.5-3 wt%.

5. The modified high-nickel cathode material according to claim 1, wherein, The additives are selected from nanoscale; And / or, the additive has a grain size of 0.01-100 nm and a specific surface area ≥150 m². 2 / g; And / or, the additive is selected from at least one of ZrF4, AlF3 and YF3; And / or, relative to 100 parts by weight of the matrix, the amount of the additive is 0.01-10 parts by weight.

6. The modified high-nickel cathode material according to claim 5, wherein, The additive has a grain size of 20-50 nm and a specific surface area of ​​180-300 m². 2 / g; And / or, relative to 100 parts by weight of the matrix, the amount of the additive is 0.1-5 parts by weight.

7. The modified high-nickel cathode material according to claim 6, wherein, The amount of the additive is 0.5-3 parts by weight relative to 100 parts by weight of the matrix.

8. The modified high-nickel cathode material according to claim 1, wherein, In the general formula of the matrix, L is selected from Co and / or Mn, M is selected from at least one of Mg, La, Al, Nb and Sr, 0.6≤x≤0.8, 0.1≤y≤0.3, 0.01≤z≤0.1, and a=0; And / or, in the composite coating layer, D is selected from at least one of Zr, Al, Y, La and Nb, 1≤p≤2, 0.99≤n≤1.01, 3≤m≤5.

9. The modified high-nickel cathode material according to claim 1, wherein, The Li n The molar ratio α of fluorine in F to fluorine in the additive satisfies: 0.3 ≤ α ≤ 1; And / or, the residual lithium is selected from lithium hydroxide and / or lithium carbonate; And / or, based on the total weight of the substrate, the concentrations of lithium hydroxide and lithium carbonate on the substrate surface are set to m1 and m2, respectively, and the concentrations of lithium hydroxide and lithium carbonate on the modified high-nickel cathode material surface are set to m3 and m4, respectively, satisfying: < The units for m1, m2, m3 and m4 are all ppm; And / or, ≥6.7%; And / or, ≥9.8%.

10. The modified high-nickel cathode material according to claim 9, wherein, The Li n The molar ratio α of fluorine in F to fluorine in the additive satisfies: 0.8 ≤ α ≤ 0.9; And / or, 13% ≤ ≤59.5%; And / or, 15.4% ≤ ≤72.7%.

11. The modified high-nickel cathode material according to claim 1, wherein, In the XRD diffraction pattern of the modified high-nickel cathode material under CuKa radiation, obvious diffraction peaks of 2θ appear at 38-38.8°, 44.5-45.5° and 64.8-66°, respectively. And / or, in the XRD diffraction pattern of the modified high-nickel cathode material obtained under CuKa radiation, the ratio β of the peak intensity of the (111) crystal plane and the peak intensity of the (003) crystal plane satisfies: 0.003≤β≤0.

02.

12. The modified high-nickel cathode material according to claim 11, wherein, In the XRD diffraction pattern of the modified high-nickel cathode material obtained under CuKa radiation, the ratio β of the peak intensity of the (111) crystal plane and the peak intensity of the (003) crystal plane satisfies: 0.005≤β≤0.

015.

13. The modified high-nickel cathode material according to claim 12, wherein, In the XRD diffraction pattern of the modified high-nickel cathode material obtained under CuKa radiation, the ratio β of the peak intensity of the (111) crystal plane and the peak intensity of the (003) crystal plane satisfies: 0.006≤β≤0.

01.

14. A method for preparing the modified high-nickel cathode material according to claims 1-13, characterized in that, The preparation method includes the following steps: (1) Provide a general formula Ni γ L δ M ε (OH)2 high nickel precursor, wherein L is selected from at least one of Co, Mn and Al, M is selected from at least one of Mg, Al, Ti, Zr, W, Mo, La, Y, Nb and Sr, γ+δ+ε=1, 0.6≤γ<1, 0.1≤δ≤0.4, 0≤ε≤0.2; (2) The high-nickel precursor and lithium source are mixed, and the resulting first mixture is calcined in a first oxygen-containing atmosphere to obtain Li (1+a) Ni x L y M z O2 high-nickel cathode material, wherein x+y+z=1, 0.6≤x<1, 0.1≤y≤0.4, 0≤z≤0.2, 0≤a<0.5; (3) The high-nickel cathode material and the general formula DF b The additives are mixed, and the resulting second mixture is sintered in a second oxygen-containing atmosphere, allowing the additives to react in situ with residual lithium on the surface of the high-nickel cathode material to form a Li-containing compound on the surface of the high-nickel cathode material. p DO (m+1) / 2 and Li n A composite coating of F is used to obtain a modified high-nickel cathode material; Wherein, D is selected from at least one of Mg, Al, Ti, Zr, W, Mo, La, Y, Nb and Sr, 0.95≤p≤2.05, 0.98≤n≤1.02, and m and b are both natural numbers from 1 to 5.

15. The preparation method according to claim 14, wherein, In step (1), the high-nickel precursor is prepared by the following method: (1-i) Provide a mixed metal salt solution containing Ni source, L source and M source; provide a precipitant solution and a complexing agent solvent; (1-ii) Under a non-oxidizing atmosphere, the mixed metal salt solution, precipitant solution and complexing agent solution are mixed and co-precipitated. The resulting precursor slurry is then filtered, washed and dried to obtain the high-nickel precursor. And / or, in step (1-i), the Ni source in terms of Ni, the L source in terms of L, and the M source in terms of M satisfy: n(Ni):n(L):n(M), where 0.6≤n(Ni)<1, 0.1≤n(L)≤0.4, and 0≤n(M)≤0.2; And / or, the Ni source, L source and M source are each independently selected from at least one of sulfate, nitrate, chlorate and acetate containing Ni, L and M; And / or, the concentration of total metal ions in the mixed metal salt solution is 0.1-5 mol / L; And / or, the concentration of the precipitant in the precipitant solution is 1-10 mol / L, and the precipitant in the precipitant solution is selected from sodium hydroxide and / or potassium hydroxide; And / or, the concentration of the complexing agent in the complexing agent solution is 0.5-5 mol / L, and the complexing agent in the complexing agent solution is selected from at least one of ammonia, disodium ethylenediaminetetraacetate, ammonium nitrate, ammonium chloride, and ammonium sulfate; And / or, in step (1-ii), the conditions for the coprecipitation reaction include: pH 10-12; temperature 50-80°C; time 5-20 h; And / or, the drying conditions include: a temperature of 110-130°C and a time of 5-10 hours.

16. The preparation method according to claim 15, wherein, In step (1-i), the Ni source, the L source, and the M source satisfy the following condition: n(Ni):n(L):n(M), where 0.6≤n(Ni)≤0.8, 0.1≤n(L)≤0.3, and 0.01≤n(M)≤0.

1.

17. The preparation method according to claim 14, wherein, In step (2), the molar ratio of the high-nickel precursor (calculated as Ni) to the lithium source (calculated as Li) satisfies: n(Ni):n(Li), where 0.6≤n(Ni)<1, 1≤n(Li)<1.5; And / or, the lithium source is selected from lithium-containing compounds; And / or, the calcination conditions include: a temperature of 700-1000℃ and a time of 5-20h.

18. The preparation method according to claim 17, wherein, In step (2), the molar ratio of the high-nickel precursor (calculated as Ni) to the lithium source (calculated as Li) satisfies: n(Ni):n(Li), where 0.6≤n(Ni)≤0.8, n(Li)=1; And / or, the lithium source is selected from at least one of lithium oxide, lithium hydroxide, lithium chloride, lithium nitrate, lithium nitrite, lithium formate, lithium acetate, lithium oxalate, lithium carbonate, lithium phosphate, dilithium hydrogen phosphate, lithium dihydrogen phosphate, and lithium citrate. And / or, the calcination conditions include: a temperature of 800-900℃ and a time of 6-12h.

19. The preparation method according to claim 18, wherein, The lithium source is selected from at least one of lithium carbonate, lithium hydroxide, and lithium chloride.

20. The preparation method according to claim 14, wherein, In step (3), the weight ratio of the high-nickel cathode material to the additive is 100:0.01-10; And / or, the sintering conditions include: a temperature of 400-850℃ and a time of 5-20h.

21. The preparation method according to claim 20, wherein, In step (3), the weight ratio of the high-nickel cathode material to the additive is 100:0.1-5; And / or, the sintering conditions include: a temperature of 600-750°C and a time of 5-8 hours.

22. The preparation method according to claim 21, wherein, In step (3), the weight ratio of the high-nickel cathode material to the additive is 100:0.5-3.

23. The modified high-nickel cathode material according to any one of claims 1-13, or the modified high-nickel cathode material prepared by the preparation method according to any one of claims 14-22, in lithium-ion batteries.

24. A lithium-ion battery, characterized in that, The lithium-ion battery comprises: the modified high-nickel cathode material according to any one of claims 1-13, or the modified high-nickel cathode material prepared by the preparation method according to any one of claims 14-22.

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