High-nickel positive electrode material with active crystal face preferentially distributed, preparation method and battery

Abstract

The invention provides a high-nickel positive electrode material with preferentially distributed active crystal faces, a preparation method and a battery, and relates to the technical field of battery materials. The high-nickel positive electrode material comprises a plurality of secondary spherical particles of the high-nickel positive electrode material, the secondary spherical particles are formed by agglomeration of a plurality of primary crystal grains, and in the secondary spherical particles, the secondary spherical particles with (110) active crystal face preferential distribution account for more than or equal to 50%. Through element doping and specific preparation method control, growth regulation and control of primary crystal grains forming secondary spherical particles are realized, active crystal face development of the primary crystal grains is promoted, the characteristic of preferred distribution of the active crystal faces of the primary crystal grains is formed, the interface impedance of the positive electrode material is effectively reduced, and the service life of the positive electrode material is prolonged. Therefore, the first-circle charge-discharge efficiency and the discharge capacity of the positive electrode material are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to a high-nickel positive electrode material with preferential distribution of active crystal faces, a preparation method and a battery. Background Art

[0002] Lithium-ion batteries have been widely used in 3C digital, vehicle power, power station energy storage and other fields. The positive electrode material is an important component of lithium-ion batteries, and the nickel-cobalt-manganese ternary material is one of the most popular positive electrode materials. At present, most of the ternary materials are secondary spherical particles formed by the agglomeration of primary grains. There are grain interfaces between the primary grains. The lithium ion diffusion of polycrystalline materials is often affected by the grain boundary diffusion between the primary grains, affecting its capacity and rate performance. In the prior art, the performance optimization of polycrystalline materials often adopts doping with metal elements. The specific preparation process is: the ternary material precursor is mixed with a lithium source and a doped metal source for sintering. The polycrystalline material obtained in this way often has the characteristics of preferential distribution of inactive crystal planes in the orientation of the primary grains, which affects the diffusion of lithium ions in the secondary particles and has poor capacity and rate performance.

[0003] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a positive electrode material, a lithium ion battery and a preparation method.

[0005] According to the first aspect of the present invention, a high-nickel positive electrode material with a preferential distribution of active crystal planes is provided, comprising a plurality of secondary spherical particles, wherein the secondary spherical particles are formed by agglomeration of a plurality of primary crystal grains, and among the plurality of the secondary spherical particles, the proportion of secondary spherical particles with a preferential distribution of (110) active crystal planes is greater than or equal to 50%. Specifically, in a single secondary spherical particle, 30% or more of the primary crystal grains show a (110) active crystal plane orientation, and the secondary spherical particle has a (110) active crystal plane preferential distribution. In this embodiment, by performing EBSD on the cross section of the secondary spherical particle to test its crystal plane distribution, the proportion of the number of primary crystal grains with a (110) active crystal plane orientation can be obtained. Further preferably, among the secondary spherical particles with a preferential distribution of (110) active crystal planes, 50% or more of the primary crystal grains show a (110) active crystal plane orientation. It should be noted that in the present invention, the active crystal plane orientation is the crystal plane exposed in the cross-sectional direction of the secondary sphere by the primary particles agglomerated to form the secondary sphere, and is characterized by the crystal plane parameter. The (110) active crystal plane orientation means that the crystal plane exposed on the cross section of the secondary sphere is the (110) crystal plane. In this embodiment, the positive electrode material has a (110) active crystal plane orientation, the (110) crystal plane is perpendicular to the (001) crystal plane, and is composed of transition metal ions and lithium ions arranged alternately. Lithium ions can pass through this crystal plane into the electrolyte for transmission, which can greatly improve the electrochemical activity of the positive electrode material.

[0006] In an exemplary embodiment of the present invention, the primary crystal grain has a major axis and a minor axis, the minor axis is ≤300 nm, and the aspect ratio of the major axis to the minor axis is ≥1.5. The primary crystal grain is elongated, which can significantly improve the anti-cracking strength of the positive electrode material, thereby improving the cycle performance of the positive electrode material.

[0007] In an exemplary embodiment of the present invention, the chemical formula of the high nickel cathode material is Li a (Ni 1-x- y Co x Mn y M b N c )O2, wherein M is a first doping element having a valence greater than or equal to 5, N is a second doping element having a valence less than or equal to 4, 0.8≤a≤1.2, 0≤x≤0.1, 0≤y≤0.1, 0≤b≤1wt%, 0≤c≤0.2wt%.

[0008] In an exemplary embodiment of the present invention, the M is selected from one or more of W, Mo, Nb and Sb, and the N is selected from one or more of Zr, Ti, Y, Al, Sr and Ce.

[0009] By doping the positive electrode material with two metal elements of different valence states, the discharge capacity and cycle performance of the positive electrode material can be effectively improved.

[0010] According to a second aspect of the present invention, there is provided a method for preparing a high-nickel positive electrode material having preferential distribution of active crystal faces as described in any one of the above items, comprising:

[0011] S1, preparing a precursor, wherein the precursor is doped with a first doping element M, wherein M is selected from one or more of W, Mo, Nb and Sb; and the doping amount of M in the outer region of the precursor is greater than the doping amount in the inner region thereof;

[0012] S2, mixing a lithium source, the precursor, a compound containing the first doping element M and / or a compound containing the second doping element N to obtain a mixture, wherein the N is selected from one or more of Zr, Ti, Y, Al, Sr and Ce;

[0013] S3, heating the mixture to a low temperature platform, keeping it warm for a first time, then heating it to a high temperature platform, keeping it warm for a second time, and then cooling it to room temperature to obtain the high nickel positive electrode material, wherein the temperature of the low temperature platform is 50 to 400°C lower than the temperature of the high temperature platform, and the first time is greater than the second time.

[0014] In an exemplary embodiment of the present invention, in step S1, the precursor is prepared according to the following steps: preparing a reaction solution, the reaction solution comprising a metal salt solution, an M salt solution, a complexing agent solution and a precipitant solution; introducing the metal salt solution and an inert gas into a reactor in parallel, then introducing the M salt solution, the complexing agent solution and the precipitant solution, controlling the pH of the reaction system to be 9 to 13, performing a precipitation reaction, and obtaining a precursor after the reaction is completed. The metal salt solution contains nickel salt, cobalt salt and manganese salt, the M salt solution is an M salt containing a first doping element M, and the nickel salt, cobalt salt, manganese salt and M salt can be sulfate, phosphate, nitrate, chloride and the like. The concentration of the metal salt solution is 0.5 to 3.0 mol / L, preferably 2 to 2.5 mol / L.

[0015] Furthermore, the precipitant is a water-soluble base, preferably NaOH or KOH; the concentration of the precipitant solution is 5 to 20 mol / L, preferably 6 to 9 mol / L.

[0016] Furthermore, the complexing agent is selected from any one of ammonia water, urea, and soluble ammonium salts. The concentration of the complexing agent solution is 2 to 10 mol / L, preferably 4 to 8 mol / L.

[0017] Furthermore, during the preparation of the precursor, the reaction temperature is 30 to 70°C, preferably 40 to 60°C.

[0018] Furthermore, in the process of preparing the precursor, at the initial stage of the reaction, the introduction rate ratio of the M salt solution to the metal salt solution is A1, and in the middle and late stages of the reaction, the introduction rate ratio of the M salt solution to the metal salt solution is A2, and A2 is 2 to 4 times of A1. Specifically, in the process of preparing the precursor, the initial stage of the reaction is within 0 to 12 hours of the reaction, and the middle and late stages of the reaction are within 12 to 30 hours of the reaction; at the initial stage of the reaction, the introduction rate of the M salt solution is 80 to 100 mL / min, and the introduction rate of the metal salt solution is 180 to 220 L / h; in the middle and late stages of the reaction, the introduction rate of the M salt solution is 780 to 820 mL / min, and the introduction rate of the metal salt solution is 580 to 620 L / h. For example, in the initial stage of the reaction (0-12h), the injection rate of the M salt solution is set to 90mL / min, and the injection rate of the metal salt solution is 200L / h. At this time, the injection rate ratio of the M salt solution / metal salt solution is 0.027; as the precursor gradually grows, in the middle and late stages of the reaction (12-30h), the injection rate ratio of the two is increased to 0.081, that is, the M salt solution rate is 810mL / min, and the metal salt solution is 600L / h, until the precipitation reaction is completed.

[0019] By doping high-valent elements in the preparation process of the precursor, and regulating the injection rate of the M salt during the preparation process, the injection rate of the M salt is low in the early stage of the growth of the precursor, and as the growth proceeds, the injection rate of the M salt is accelerated, so as to achieve a content gradient distribution of the doping element M in the precursor. Specifically, the mass fraction of the M in the precursor is 0.2% to 0.6%. The outer region of the precursor is defined as a region extending 2 to 3 μm inward from the surface of the precursor; the inner region of the precursor is a region extending 2 to 3 μm outward from the center of the precursor. The ratio of the doping amount of M in the outer region of the precursor to the doping amount in its inner region is greater than or equal to 3. Since the doping amount of M on the outer side of the precursor is higher, it is easier to develop and grow primary particles than internal particles during sintering, so that the primary grains form slender features and are conducive to the realization of the preferred orientation of the (110) active crystal plane.

[0020] In an exemplary embodiment of the present invention, in step S2, the lithium source is selected from lithium hydroxide, lithium carbonate, lithium nitrate, lithium acetate, etc. The compound containing the first doping element M and the compound containing the second doping element N may be oxides or metal salts.

[0021] In an exemplary embodiment of the present invention, in step S3, the low temperature platform is 450-650°C, and the first time is 4-10h, preferably 4-6h. The high temperature platform is 700-850°C, and the second time is 0.3-1h, preferably 0.5h. The heating rate to the low temperature platform is greater than or equal to 3°C / min, and the heating rate to the high temperature platform is less than or equal to 2.5°C / min. Through the above-mentioned sintering process, the sintering temperature curve has a low temperature platform full reaction and pulse heating characteristics (what does the pulse heating characteristic mean, please explain), so that the active crystal plane of the primary grain can be fully developed and the proportion of active crystal planes is increased. And the high temperature platform time in the sintering curve is short, which can effectively avoid the development of inactive crystal planes in the primary grains, effectively reduce the material interface impedance, and improve the discharge capacity of the positive electrode material.

[0022] According to a third aspect of the present invention, a lithium ion battery is provided, comprising a high nickel positive electrode material with preferential distribution of active crystal faces as described in any one of the above, or a high nickel positive electrode material prepared according to any one of the preparation methods described in any one of the above. It is understood that the lithium ion battery can be prepared according to the method in the prior art, and this embodiment will not be repeated here.

[0023] The beneficial effects of the high-nickel positive electrode material with preferential distribution of active crystal faces, the preparation method and the battery of the embodiment of the present invention are:

[0024] Compared with the prior art, the high-nickel positive electrode material provided by the embodiment of the present invention has a primary crystal plane that constitutes the secondary spherical particles changed from a preferential distribution of inactive crystal planes to a preferential distribution of active crystal planes, thereby improving the rate discharge performance of the material and reducing the interface impedance.

[0025] The method for preparing the high-nickel positive electrode material of the embodiment of the present invention, by doping high-valent elements in the precursor preparation process, the high-valent elements will inhibit the growth and development of primary grains during the sintering process, so that the primary grains form slender morphological features. The primary grains on the surface of the secondary spherical particles are affected by direct contact with the lithium source, and are easier to develop and grow than the internal primary grains during the sintering process. Gradient doping is achieved through flow control during the precursor doping process, so that the surface part has a higher amount of doping elements, ensuring that both the internal and external primary particles have slender features.

[0026] In addition, during the sintering process, the temperature rise platform is controlled. After the sintering time of the low-temperature platform is extended, the lithium source and the precursor fully react at low temperature, promoting the development of active crystal faces of the positive electrode material; the process of reheating to the high-temperature platform can ensure that lithium is fully diffused in the secondary spherical precursor; the high-temperature platform greatly shortens the time, which can inhibit the development of inactive crystal faces and retain the characteristics of the preferential orientation distribution of the active crystal faces of the primary particles.

[0027] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 This is a SEM image of the positive electrode material obtained in Example 2 of the present invention.

[0030] Figure 2 This is the EBSD test image of the cross section of the secondary spherical particles of the positive electrode material obtained in Example 2 of the present invention.

[0031] Figure 3 It is a comparison diagram of discharge curves of Example 2 of the present invention and Comparative Example 3.

[0032] Figure 4 It is a comparison chart of the EIS test results of Example 2 of the present invention and Comparative Example 3. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the embodiments of the present disclosure clearer, the technical scheme in the embodiments of the present disclosure will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0034] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0035] Example 1

[0036] This embodiment provides a doping precursor, which is obtained by following the steps below:

[0037] (1) According to the chemical formula [Ni 0.95 Co 0.04 Mn 0.01 ](OH)2 in a stoichiometric ratio, nickel sulfate, cobalt sulfate and manganese sulfate are prepared into a 2mol / L metal salt solution, and impurities are removed by filtering; ammonia water is prepared into a 2mol / L complexing agent solution; NaOH is prepared into an 8mol / L precipitant solution, and ammonium metatungstate is prepared into a tungsten salt solution according to a doping amount of 0.3wt%; and the above four solutions are deoxygenated.

[0038] (2) Nitrogen is introduced into the reactor to maintain an inert atmosphere, the stirring speed is set to 1200 rpm, the metal salt solution and the inert gas are introduced into the reactor in parallel, and the tungsten salt solution, the complexing agent solution, and the precipitant solution are introduced into the reactor evenly at the same time. During this process, the pH of the system is controlled to be 11-12. In the initial stage of the precipitation reaction (0-12h), the injection rate of the tungsten salt solution is set to 90mL / min, and the injection rate of the metal salt M solution is set to 200L / h. In the middle and late stages of the precipitation reaction (12-30h), the injection rate of the tungsten salt solution is set to 810mL / min, and the injection rate of the metal salt solution is set to 600L / h until the precipitation reaction is completed.

[0039] (3) After the reaction is completed, the material is centrifuged, washed, and dried to obtain a doping precursor.

[0040] Embodiments 2 to 6

[0041] This embodiment provides a high-nickel positive electrode material, which is obtained by following the steps below:

[0042] (1) The doping precursor prepared in Example 1, lithium hydroxide, an oxide containing a doping element M, and an oxide containing a doping element N are mixed to obtain a mixture. The doping precursor and lithium hydroxide are prepared according to a molar ratio of Li to the sum of Ni, Co, and Mn of 1:1, and the materials and doping amounts of M and N are shown in Table 1 below.

[0043] (2) The mixture is sintered in a sintering furnace to obtain a positive electrode material. The sintering process is: heating to 500°C at a rate of 3°C / min, keeping at 500°C for a first time T1, then heating to 700°C at a rate of 2°C / min, keeping at 700°C for a second time T2, and then cooling to room temperature at a rate of 4°C / min to obtain a high-nickel positive electrode material. The first time T1 and the second time T2 are shown in Table 1.

[0044] The structure of the positive electrode material obtained in Example 2 is as follows Figure 1 As shown in the figure, the structure of the positive electrode material is a secondary spherical particle formed by the agglomeration of primary particles, and the primary particles inside it show slender characteristics. The cross-sectional EBSD test image of the secondary spherical particle is shown in Figure 2 As shown, the test results show that the primary particles mainly present a (110) crystal plane orientation.

[0045] Comparative Example 1

[0046] This embodiment provides a high-nickel positive electrode material, which is obtained by following the steps below:

[0047] (1) A precursor is obtained by coprecipitation method, and the chemical formula of the precursor is [Ni 0.95 Co 0.04 Mn 0.01](OH)2, the precursor does not contain any doping elements.

[0048] (2) The precursor, lithium hydroxide, WO3 and Al2O3 are mixed uniformly, wherein the ratio of lithium hydroxide to the precursor is Li:(Ni+Mn+Co) in a molar ratio of 1.0, and the doping amounts of W and Al are shown in Table 1. After uniform mixing, a mixture is obtained.

[0049] (3) The mixture is sintered in a sintering furnace. The sintering process is as follows: heating to 500°C at a rate of 3°C / min, keeping at 500°C for 6 hours, then heating to 700°C at a rate of 3°C / min, keeping at 700°C for 0.5 hours, and then cooling to room temperature at a cooling rate of 4°C / min.

[0050] Comparative Example 2

[0051] This comparative example provides a high-nickel positive electrode material, which differs from comparative example 1 in that WO3 is replaced by ZrO2.

[0052] Comparative Example 3

[0053] This comparative example provides a high-nickel positive electrode material, which is prepared in the manner of Example 1. The difference between this comparative example and Example 1 is that the first time T1 and the second time T2 are different, as shown in Table 1 for details.

[0054] Comparative Example 4

[0055] This comparative example provides a high-nickel positive electrode material, which is prepared in the manner of Example 1. The difference between this comparative example and Example 1 is that the doping element in the precursor is Al, and the doping amount remains unchanged.

[0056] The high nickel positive electrode materials, superconducting carbon black SP and polyvinylidene fluoride PVDF prepared in Examples 2 to 6 and Comparative Examples 1 to 4 were mixed in a mass ratio of 94:3:3, and the mixture was adjusted into a slurry with N-methyl-pyrrolidone (NMP); the slurry was evenly coated on the aluminum foil current collector to obtain a positive electrode film. A metal lithium sheet was used as the negative electrode, a polypropylene microporous membrane was used as the diaphragm, and 1 mol / LiPF6 (the solvent was a mixture of ethylene carbonate and dimethyl carbonate in a volume ratio of 1:1) was used as the electrolyte to assemble a button cell in an Ar gas protected glove box. The following tests were performed respectively:

[0057] a) The button cell prepared above was subjected to a discharge capacity test, under the test conditions of charging the button cell to 4.3V at a rate of 0.1C, then charging at a constant voltage of 4.3V until the current rate was reduced to 0.02C, and standing for 5 minutes; then discharging the button cell at a rate of 0.1C to 3.0V to obtain the discharge capacity;

[0058] b) After the above button cell capacity test, a cycle capacity test is performed. The test condition is that the button cell is cycled at a charge and discharge rate of 0.1C at 45°C, and the capacity retention rate is calculated by comparing the discharge capacity at the 20th cycle with the discharge capacity at the 1st cycle.

[0059] The test results are shown in Table 1:

[0060] Table 1

[0061]

[0062] a: (110) active crystal plane ratio refers to the ratio of the number of primary particles with (110) crystal plane orientation in the secondary spherical particles.

[0063] As can be seen from Table 1, compared with Comparative Examples 1 to 3, Examples 2 to 6 have a high proportion of (110) active crystal faces and a large average aspect ratio for the positive electrode materials obtained, and can obtain good discharge capacity and cycle performance. The precursors of Comparative Examples 1 and 2 were not doped, and the obtained positive electrode materials had a small aspect ratio and poor cycle performance. In Comparative Example 3, the sintering time of the low-temperature platform was short and the sintering time of the high-temperature platform was long, resulting in a low proportion of (110) active crystal faces, a reduced discharge capacity, and a higher interface impedance than that of Example 2, as shown in FIG. Figure 3 and Figure 4 The precursor of Comparative Example 4 is doped with low-valent Al, which is not conducive to the improvement of cycle performance.

[0064] The above description is not all embodiments. The detailed description of the embodiments of the present disclosure is not intended to limit the scope of the present disclosure for protection, but merely represents selected embodiments of the present disclosure. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present disclosure.

Claims

1. A high nickel cathode material with preferential distribution of active crystal faces, characterized in that: It includes a plurality of secondary spherical particles, wherein the secondary spherical particles are formed by agglomeration of a plurality of primary crystal grains, and among the plurality of secondary spherical particles, the proportion of secondary spherical particles having a preferential distribution of (110) active crystal planes is greater than or equal to 50%, wherein among the secondary spherical particles having a preferential distribution of (110) active crystal planes, 30% or more of the primary crystal grains show (110) active crystal plane orientation.

2. The high nickel positive electrode material with preferential distribution of active crystal faces according to claim 1, characterized in that: The primary grain has a major axis and a minor axis, the minor axis is ≤300 nm, and an aspect ratio of the major axis to the minor axis is ≥1.

5.

3. The high nickel positive electrode material with preferential distribution of active crystal faces according to claim 1, characterized in that: The chemical formula of the high nickel cathode material is Li a (Ni 1-x-y Co x Mn y M b N c )O2, wherein M is a first doping element having a valence greater than or equal to 5, N is a second doping element having a valence less than or equal to 4, 0.8≤a≤1.2, 0≤x≤0.1, 0≤y≤0.1, 0≤b≤1wt%, 0≤c≤0.2wt%.

4. The high nickel positive electrode material with preferential distribution of active crystal faces according to claim 3, characterized in that: The M is selected from one or more of W, Mo, Nb and Sb, and the N is selected from one or more of Zr, Ti, Y, Al, Sr and Ce.

5. A method for preparing a high-nickel positive electrode material with preferential distribution of active crystal faces as claimed in any one of claims 1 to 4, characterized in that: include: S1, preparing a precursor, wherein the precursor is doped with a first doping element M, wherein M is selected from one or more of W, Mo, Nb and Sb; and the doping amount of M in the outer region of the precursor is greater than the doping amount in the inner region thereof; S2, mixing a lithium source, the precursor, a compound containing the first doping element M and / or a compound containing the second doping element N to obtain a mixture, wherein the N is selected from one or more of Zr, Ti, Y, Al, Sr and Ce; S3, heating the mixture to a low temperature platform, keeping it warm for a first time, then heating it to a high temperature platform, keeping it warm for a second time, and then cooling it to room temperature to obtain the high nickel positive electrode material, wherein the temperature of the low temperature platform is 50 to 400°C lower than the temperature of the high temperature platform, and the first time is greater than the second time.

6. The preparation method according to claim 5, characterized in that: In step S1, the precursor is prepared according to the following steps: preparing a reaction solution, wherein the reaction solution includes a metal salt solution, an M salt solution, a complexing agent solution and a precipitant solution; introducing the metal salt solution and an inert gas into a reactor in parallel, and then introducing the M salt solution, the complexing agent solution and the precipitant solution, controlling the pH of the reaction system to be 9 to 13, and performing a precipitation reaction, wherein the metal salt solution contains nickel salt, cobalt salt and manganese salt, and in the initial stage of the reaction, the introduction rate ratio of the M salt solution to the metal salt solution is A1, and in the middle and late stages of the reaction, the introduction rate ratio of the M salt solution to the metal salt solution is A2, and A2 is 2 to 4 times that of A1.

7. The preparation method according to claim 6, characterized in that: During the preparation of the precursor, the initial reaction period is within 0 to 12 hours of the reaction, and the middle and late reaction period is within 12 to 30 hours of the reaction; in the initial reaction period, the introduction rate of the M salt solution is 80 to 100 mL / min, and the introduction rate of the metal salt solution is 180 to 220 L / h; in the middle and late reaction period, the introduction rate of the M salt solution is 780 to 820 mL / min, and the introduction rate of the metal salt solution is 580 to 620 L / h.

8. The preparation method according to claim 5, characterized in that: The mass fraction of M in the precursor is 0.2% to 0.6%; the outer region of the precursor is a region extending 2 to 3 μm inward from the surface of the precursor; the inner region of the precursor is a region extending 2 to 3 μm outward from the center of the precursor, and the ratio of the doping amount of M in the outer region of the precursor to the doping amount in its inner region is greater than or equal to 3.

9. The preparation method according to claim 5, characterized in that: The low temperature platform is 450-650°C, and the first time is 4-10 hours; the high temperature platform is 700-850°C, and the second time is 0.3-1 hour; the heating rate to the low temperature platform is greater than or equal to 3°C / min, and the heating rate to the high temperature platform is less than or equal to 2.5°C / min.

10. A lithium ion battery, characterized in that: The invention comprises a high-nickel positive electrode material with preferential distribution of active crystal faces as claimed in any one of claims 1 to 4, or a high-nickel positive electrode material prepared by a preparation method according to any one of claims 5 to 9.

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