Nickel-manganese binary precursor and its preparation method and application, cathode material, lithium-ion battery

Abstract

The present invention relates to the technical field of lithium-ion batteries, and specifically relates to a nickel-manganese binary precursor and its preparation method and application, a cathode material, and a lithium-ion battery. The precursor has the composition shown in Formula I, Ni x Mn y M z (OH)2 (I), where 0.8 ≤ x < 1, 0 < y ≤ 0.2, 0 ≤ z ≤ 0.1, and x + y + z = 1, and M is selected from at least one non-Co element; wherein, in the powder X-ray diffraction measurement of the precursor using CuKα radiation, characteristic double peaks of the 001 crystal plane are present in the range of 2θ from 19 ± 1.5°. The precursor provided by the present invention has XRD diffraction {001} double peaks, thereby improving the crystallinity of the particles, enabling the cathode material to have a high tap density while satisfying the structural stability, and thus improving the capacity, rate performance, and cycle performance of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion batteries, and particularly relates to a nickel-manganese binary precursor, a preparation method and application thereof, a cathode material containing the nickel-manganese binary precursor, and a lithium ion battery containing the cathode material. Background Art

[0002] While high-nickel materials have high energy density, their disadvantages are also relatively obvious. The particles on the surface are prone to irreversible phase transformation, and their structural stability and high-temperature stability are poor. Moreover, in recent years, the price of cobalt has risen, resulting in a substantial increase in the cost of nickel-cobalt-manganese ternary materials. In order to reduce costs, the trend of low-cobalt and cobalt-free ternary materials has become a research focus. However, the main role of cobalt in ternary materials is to improve crystal conductivity and structural stability. Therefore, optimizing the performance of cobalt-free binary materials is extremely important.

[0003] The indicators of the precursor have a decisive influence on the basic properties of the cathode material. The micro-spherical morphology of high-nickel electrode materials not only has a huge impact on their tap density, but also affects the contact between the cathode material and the electrolyte, thereby affecting the side reactions during charge and discharge and the material performance. The particle morphology of the precursor is determined by the morphology and arrangement of primary fibers. Currently, the main method for preparing the precursor is co-precipitation. During the process, parameters such as introducing protective gas or oxidizing gas, regulating pH, temperature, complexing agent concentration, liquid feeding rate, and stirring speed are controlled to effectively control the morphology and arrangement of primary fibers and achieve the purpose of controlling the precursor morphology. However, each parameter has a synergistic effect on the growth of the crystal plane of primary fibers, and it is not easy to achieve the goal. The {001} crystal plane of the ternary precursor is a low-energy plane, and during co-precipitation, the crystal is prone to grow along the a-axis and b-axis, resulting in an overly large size of the {001} closed crystal plane, and the Li + transmission path becomes longer, which is not conducive to exerting the output performance.

[0004] Therefore, there is an urgent need for a high-nickel cobalt-free cathode material with high capacity, high rate performance, and high cycle performance. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above technical problems and provide a nickel-manganese binary precursor, a preparation method thereof, a cathode material, and a lithium ion battery. The precursor has XRD diffraction {001} double peaks, which improves the crystallinity of the precursor particles, and further improves the capacity, rate performance, cycle performance, and safety performance of the lithium ion battery.

[0006] To achieve the above purpose, in the first aspect of the present invention, a nickel-manganese binary precursor is provided. The precursor has the composition shown in Formula I, Ni x Mn y M z (OH) 2(I), 0.8 ≤ x < 1, 0 < y ≤ 0.2, 0 ≤ z ≤ 0.1, and x + y + z = 1, where M is selected from at least one non-Co element;

[0007] Among them, in the powder X-ray diffraction measurement of the precursor using CuKα rays, the characteristic double peaks of the 001 crystal plane are within the range of 2θ at 19 ± 1.5°.

[0008] In the present invention, without special instructions, the nickel-manganese binary precursor is simply referred to as the precursor.

[0009] Preferably, in the powder X-ray diffraction measurement of the precursor using CuKα rays, the peak intensity ratio of the characteristic peak of the 101 crystal plane to the characteristic double peaks of the 001 crystal plane satisfies: I (101) / I (001) ≥ 1.5, where the characteristic peak of the 101 crystal plane has 2θ within the range of (37 - 41)°.

[0010] Preferably, the characteristic double peaks of the 001 crystal plane include single peak A and single peak B, and single peak A is located to the left of single peak B.

[0011] Preferably, the peak intensities of single peak A and single peak B satisfy: 500 ≤ I (A) ≤ 2000, 600 ≤ I (B) ≤ 2000, 0.35 ≤ I (A) / I (B) ≤ 2.4.

[0012] Preferably, the full width at half maximum (FWHM) of single peak A and single peak B satisfies: 0.4° ≤ FWHM (A) ≤ 0.7°, 0.4° ≤ FWHM (B) ≤ 0.6°, 0.7 ≤ FWHM (A) / FWHM (B) ≤ 1.5.

[0013] Preferably, the peak areas of single peak A and single peak B satisfy: 10000 ≤ A (A) ≤ 70000, 10000 ≤ A (B) ≤ 75000, 0.6 ≤ A (A) / A (B) ≤ 2.2.

[0014] The second aspect of the present invention provides a method for preparing a nickel-manganese binary precursor, the preparation method comprising: mixing a mixed salt solution, a complexing agent, and a precipitating agent and performing a coprecipitation reaction, controlling the oxygen content in the reaction system to be 0.5 - 10% by volume and the pH value to be 10 - 11.3, and successively washing and drying the obtained coprecipitation reaction product to obtain the precursor;

[0015] Among them, the mixed salt solution is selected from an aqueous solution containing a nickel salt, a manganese salt, and an optional M source, and M in the M source is selected from at least one non-Co element.

[0016] The third aspect of the present invention provides an application of the precursor provided in the first aspect, or the precursor prepared by the preparation method provided in the second aspect, in a cathode material.

[0017] The fourth aspect of the present invention provides a cathode material, which is prepared by sintering the precursor provided in the first aspect, or the precursor prepared by the preparation method provided in the second aspect.

[0018] Preferably, the cathode material is prepared by the following method: in an oxygen-containing atmosphere, when the precursor does not contain a doping element M, the precursor, a lithium source, and an M source are mixed and sintered to obtain the cathode material; or, when the precursor contains a doping element M, the precursor and a lithium source are mixed and sintered to obtain the cathode material; where M in the M source is selected from at least one non-Co element.

[0019] The fifth aspect of the present invention provides a lithium-ion battery, which contains the cathode material provided in the fourth aspect.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) For the precursor provided by the present invention, by defining that the precursor has characteristic double peaks on the 001 crystal plane of XRD diffraction, the crystallinity of the particles is improved. In particular, by defining I (101) / I (001) ≥1.5, the crystallinity of the precursor is further improved, so that the cathode material sintered from the precursor has a high tap density on the premise of meeting the structural stability.

[0022] (2) For the preparation method of the precursor provided by the present invention, the co-precipitation technical means is adopted, and the oxygen content in the reaction system is controlled to be 0.5-10% by volume and the pH value is 10-11.3, so that the precursor generates XRD diffraction double peaks; at the same time, this preparation method simplifies the process flow and has a relatively low cost, which is suitable for industrial production;

[0023] (3) Using the precursor provided by the present invention in a lithium-ion battery can effectively improve the capacity, rate performance, and capacity retention rate of the battery. Description of the Drawings

[0024] Figure 1 is an SEM image of the precursor S1 prepared in Example 1, where Figure 1a-1b is the SEM image of the primary particles of the precursor S1, Figure 1c-1d is the SEM image of the secondary particles of the precursor S1;

[0025] Figure 2 It is the XRD pattern of the precursor S1 prepared in Example 1;

[0026] Figure 3 is the SEM image of the precursor S2 prepared in Example 2, where Figure 3a-3b is the SEM image of the primary particles of the precursor S2, Figure 3c-3d is the SEM image of the secondary particles of the precursor S2;

[0027] Figure 4 is the XRD pattern of the precursor S2 prepared in Example 2;

[0028] Figure 5 is the SEM image of the precursor S3 prepared in Example 3, where Figure 5a-5b is the SEM image of the primary particles of the precursor S3, Figure 5c-5d is the SEM image of the secondary particles of the precursor S3;

[0029] Figure 6 is the XRD pattern of the precursor S3 prepared in Example 3;

[0030] Figure 7 is the SEM image of the precursor DS1 prepared in Comparative Example 1, where Figure 7a-7b is the SEM image of the primary particles of the precursor DS1, Figure 7c-7d is the SEM image of the secondary particles of the precursor DS1;

[0031] Figure 8 is the XRD pattern of the precursor DS1 prepared in Comparative Example 1. Detailed implementation mode

[0032] In the ranges disclosed herein, the endpoints and any values are not limited to the exact 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 each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0033] The first aspect of the present invention provides a nickel-manganese binary precursor, and the precursor has the composition shown in Formula I, Ni x Mn y M z (OH) 2 (I), 0.8 ≤ x < 1, 0 < y ≤ 0.2, 0 ≤ z ≤ 0.1, and x + y + z = 1, and M is selected from at least one non-Co element;

[0034] Among them, in the powder X-ray diffraction measurement of the precursor using CuKα radiation, characteristic double peaks of the 001 crystal plane are present in the range of 2θ of 19 ± 1.5°.

[0035] In the present invention, without special circumstances, in Formula I, M being selected from at least one non-Co element means that the precursor is a high-nickel cobalt-free binary material, that is, M is selected from elements other than Co.

[0036] In the present invention, without special circumstances, the precursor having characteristic double peaks of the 001 crystal plane in the range of 2θ at 19 ± 1.5° means that the XRD peak of the 001 crystal plane of the precursor is split into double peaks, that is, split into a single peak A on the left and a single peak B on the right.

[0037] In some embodiments of the present invention, in Formula I, 0.8 ≤ x < 1, 0 < y ≤ 0.2, 0 ≤ z ≤ 0.1, and x + y + z = 1, and M is selected from at least one non-Co element.

[0038] In some embodiments of the present invention, further preferably, in Formula I, 0.85 ≤ x ≤ 0.99, 0.01 ≤ y ≤ 0.15, 0.001 ≤ z ≤ 0.1, and x + y + z = 1, and M is selected from at least one element among La, Cr, Mo, Ca, Fe, Hf, Ti, Zn, Y, Zr, Si, W, Nb, Sm, V, Mg, B, Y, and Al.

[0039] In some embodiments of the present invention, more preferably, in Formula I, 0.9 ≤ x ≤ 0.98, 0.02 ≤ y ≤ 0.1, 0.001 ≤ z ≤ 0.01, and x + y + z = 1, and M is selected from at least one element among La, Cr, Mo, Hf, Ti, Zn, Y, Zr, W, Nb, V, Mg, B, Y, and Al.

[0040] In the present invention, by regulating the subscripts (x, y, z) of each metal element and the type of M element in Formula I, the tap density of the cathode material containing the precursor is further regulated, and then the electrochemical performance of the lithium-ion battery is regulated.

[0041] In some embodiments of the present invention, preferably, in the powder X-ray diffraction measurement of the precursor using CuKα radiation, the peak intensity ratio of the characteristic peak of the 101 crystal plane to the characteristic double peaks of the 001 crystal plane satisfies: I (101) / I (001) ≥ 1.5, for example, 1.5, 1.8, 2 / 2.2, 2.5, 2.8, 3, and any value in the range composed of any two numerical values, preferably satisfying: 1.5 ≤ I (101) / I (001) ≤ 3, wherein the characteristic peak of the 101 crystal plane is in the range of 2θ at (37 - 41)°.

[0042] In the present invention, when I (101) / I (001)When it meets the above range, the precursor has high crystallinity. After being sintered into a cathode material, it can inhibit excessive dissolution of lithium, especially inhibit the gas generation caused by the reaction of the electrolyte and the excessive lithium, improve the structural stability during lithium deintercalation and intercalation, and thus can become a lithium composite oxide with less oxygen deficiency, enabling the cathode material to have a high tap density, and enabling a lithium ion battery containing the cathode material to have a high initial charge-discharge capacity, initial efficiency, rate performance, and high capacity retention rate.

[0043] In some embodiments of the present invention, preferably, the peak intensity I of the characteristic double peaks of the 001 crystal plane (001) is 300 - 4000, preferably 500 - 3000; the full width at half maximum FWHM (001) is (0.5 - 2)°, preferably (0.6 - 1.8)°. In the present invention, it is known from Jade analysis that the reason for the appearance of the split peaks of the 001 crystal plane is the presence of nickel manganese oxide heterophase in the nickel manganese hydroxide crystal, and manganese mainly plays a role in stabilizing the structure and improving the safety performance of the material.

[0044] In some embodiments of the present invention, preferably, as Figure 2 , Figure 4 and Figure 6 shown, the characteristic double peaks of the 001 crystal plane include single peak A and single peak B, and the single peak A is located on the left side of the single peak B.

[0045] In some embodiments of the present invention, preferably, the peak intensities of the single peak A and the single peak B satisfy: 500 ≤ I (A) ≤ 2000, 600 ≤ I (B) ≤ 2000, 0.35 ≤ I (A) / I (B) ≤ 2.4.

[0046] In some embodiments of the present invention, preferably, the full widths at half maximum of the single peak A and the single peak B satisfy: 0.4° ≤ FWHM (A) ≤ 0.7°, 0.4° ≤ FWHM (B) ≤ 0.6°, 0.7 ≤ FWHM (A) / FWHM (B) ≤ 1.5.

[0047] In some embodiments of the present invention, preferably, the peak areas of the single peak A and the single peak B satisfy: 10000 ≤ A (A) ≤ 70000, 10000 ≤ A (B) ≤ 75000, 0.6 ≤ A (A) / A (B) ≤ 2.2.

[0048] In the present invention, by defining that the peak intensities, full-width at half-maximum, and peak areas of unimodal peak A and unimodal peak B satisfy the above ranges, the precursor has large BET, tap density, and narrow particle size distribution.

[0049] In some embodiments of the present invention, preferably, the precursor is a secondary particle composed of primary particles, and the primary particles have a wedge-shaped structure; more preferably, the precursor has a spherical structure.

[0050] In some embodiments of the present invention, preferably, the BET of the precursor is 3 - 25 m 2 / g, for example, 3 m 2 / g, 5 m 2 / g, 10 m 2 / g, 15 m 2 / g, 20 m 2 / g, 25 m 2 / g, and any value within the range composed of any two numerical values, preferably 5 - 20 m 2 / g; the tap density ≥ 1 g / cm 3 , for example, 1 g / cm 3 , 1.3 g / cm 3 , 1.5 g / cm 3 , 2 g / cm 3 , 2.5 g / cm 3 , and any value within the range composed of any two numerical values, preferably 1.3 - 2.5 g / cm 3 .

[0051] In some embodiments of the present invention, preferably, the particle size distribution K 90 of the precursor satisfies: 0.4 ≤ K 90 ≤ 0.8, for example, 0.4, 0.5, 0.6, 0.7, 0.8, and any value within the range composed of any two numerical values, where K 90 = (D 90 - D 10 ) / D 50 , and D 90 , D 10 and D 50 respectively refer to the particle diameters of the precursor at cumulative volume values of 90%, 10%, and 50% in the particle size distribution, and the unit is μm.

[0052] In some embodiments of the present invention, preferably, the D 50 of the precursor is 6 - 20 μm, preferably 8 - 14 μm.

[0053] The second aspect of the present invention provides a method for preparing a nickel-manganese binary precursor, the preparation method comprising: mixing a mixed salt solution, a complexing agent and a precipitating agent and carrying out a coprecipitation reaction, controlling the oxygen content in the reaction system to be 0.5-10% by volume and the pH value to be 10-11.3, and successively washing and drying the obtained coprecipitation reaction product to obtain a precursor;

[0054] Wherein, the mixed salt solution is selected from an aqueous solution containing a nickel salt, a manganese salt and an optional M source, and M in the M source is selected from at least one non-Co element.

[0055] In the present invention, by controlling the oxygen content in the reaction system to be 0.5-10% by volume, for example, 0.5% by volume, 1% by volume, 2% by volume, 5% by volume, 8% by volume, 10% by volume, and any value within the range composed of any two numerical values, an XRD diffraction split double peak is generated in the precursor. Preferably, the oxygen content in the reaction system is adjusted to 0.5-8% by volume. When the oxygen content is low, the precursor is in a hydroxide state and there is no splitting peak phenomenon in the 001 peak; when the oxygen content is high, most of the crystal is composed of oxides, the primary fibers are thinner, there is no splitting peak phenomenon in the 001 peak, and the half-peak width is narrower.

[0056] In some embodiments of the present invention, preferably, when the complexing agent is selected from a compound containing an ammonium ion, the ammonia concentration in the reaction system is controlled to be 1-12 g / L, for example, 1 g / L, 2 g / L, 5 g / L, 8 g / L, 10 g / L, 12 g / L, and any value within the range composed of any two numerical values, preferably 3-8 g / L.

[0057] In some embodiments of the present invention, preferably, the conditions of the coprecipitation reaction include: the temperature is 50-80 °C, the pH value is 10-11.3, preferably 10.3-11.1; the rotation speed is 250-750 rpm.

[0058] In the present invention, by controlling the time of the coprecipitation reaction, the particle size of the precursor is further controlled. As the time of the coprecipitation reaction prolongs, the particles of the coprecipitation reaction product gradually grow and the crystallinity is continuously improved; during the reaction process, the particle size of the slurry is tested with a laser particle size analyzer every 2 h, and by adjusting the pH value in the reaction kettle, the pH in the reaction kettle is maintained within the range of (10-11.3) ± 0.1.

[0059] In some embodiments of the present invention, preferably, in terms of metal elements, the nickel salt, manganese salt and M source satisfy n(Ni):n(Mn):n(M), where 0.8 ≤ n(Ni) < 1, 0 < n(Mn) ≤ 0.2, and 0 ≤ n(M) ≤ 0.1; more preferably, 0.85 ≤ n(Ni) ≤ 0.99, 0.01 ≤ n(Mn) ≤ 0.15, 0.001 ≤ n(M) ≤ 0.1; even more preferably, 0.9 ≤ n(Ni) ≤ 0.98, 0.02 ≤ n(Mn) ≤ 0.1, 0.001 ≤ n(M) ≤ 0.01.

[0060] In some embodiments of the present invention, preferably, M in the M source is selected from at least one element among La, Cr, Mo, Ca, Fe, Hf, Ti, Zn, Y, Zr, Si, W, Nb, Sm, V, Mg, B, Y, and Al; more preferably, M in the M source is selected from at least one element among La, Cr, Mo, Hf, Ti, Zn, Y, Zr, W, Nb, V, Mg, B, Y, and Al.

[0061] In some embodiments of the present invention, the nickel salt includes, but is not limited to, nickel sulfate, nickel nitrate, nickel chlorate, etc.; the manganese salt includes, but is not limited to, manganese sulfate, manganese nitrate, manganese chlorate, etc.; the M source includes, but is not limited to, at least one selected from oxides, sulfates, nitrates, and chlorates containing M.

[0062] In a specific embodiment of the present invention, the M source is selected from at least one of oxides, sulfates, nitrates, and chlorates containing La, Cr, Mo, Ca, Fe, Hf, Ti, Zn, Y, Zr, Si, W, Nb, Sm, V, Mg, B, Y, and Al, preferably selected from at least one of oxides, sulfates, nitrates, and chlorates containing La, Cr, Mo, Hf, Ti, Zn, Y, Zr, W, Nb, V, Mg, B, Y, and Al.

[0063] In some embodiments of the present invention, preferably, in terms of metal elements, the concentration of the mixed salt solution is 0.1 - 10 mol / L, and the nickel salt, manganese salt and M source satisfy n(Ni):n(Mn):n(M), where 0.8 ≤ n(Ni) < 1, 0 < n(Mn) ≤ 0.2, and 0 ≤ n(M) ≤ 0.1; more preferably, 0.85 ≤ n(Ni) ≤ 0.99, 0.01 ≤ n(Mn) ≤ 0.15, 0.001 ≤ n(M) ≤ 0.1; even more preferably, 0.9 ≤ n(Ni) ≤ 0.98, 0.02 ≤ n(Mn) ≤ 0.1, 0.001 ≤ n(M) ≤ 0.01.

[0064] In the present invention, the particle size range of the precursor is regulated by controlling the liquid feeding flow rate of the mixed salt. Preferably, the liquid feeding flow rate of the mixed metal salt is 50 - 300 mL / min, more preferably 150 - 250 mL / min.

[0065] In a specific embodiment of the present invention, the precipitant includes but is not limited to sodium hydroxide and / or potassium hydroxide; the complexing agent includes but is not limited to ammonia water, etc. In the present invention, both the precipitant and the complexing agent exist in the form of aqueous solutions, and the concentrations of the precipitant aqueous solution and the complexing agent aqueous solution are independently 5 - 13.3 mol / L.

[0066] In some embodiments of the present invention, preferably, the washing process includes: alternately subjecting the coprecipitation reaction product to alkali washing and water washing.

[0067] In a specific embodiment of the present invention, the washing process includes: subjecting the precipitation reaction product to alkali washing with an alkali solution to obtain an alkali-washed product, and then subjecting the obtained product to water washing with deionized water to obtain a water-washed product; repeating the above operations 1 - 5 times on the above water-washed product to obtain the precursor. In the present invention, the alkali solution includes but is not limited to a sodium hydroxide solution and / or a potassium hydroxide solution with a concentration of 0.1 - 2 mol / L.

[0068] In some embodiments of the present invention, preferably, the drying conditions include: a temperature of 80 - 150 °C and a time of 2 - 6 h.

[0069] The third aspect of the present invention provides an application of the precursor provided in the first aspect, or the precursor prepared by the preparation method provided in the second aspect, in a cathode material.

[0070] The fourth aspect of the present invention provides a cathode material, which is prepared by sintering the precursor provided in the first aspect, or the precursor prepared by the preparation method provided in the second aspect.

[0071] In the present invention, when the above precursor is used in a cathode material, the excessive dissolution of lithium can be inhibited, especially the gas generation caused by the reaction between the electrolyte and the excessive lithium can be inhibited, and the structural stability during lithium deintercalation and intercalation can be improved. Thus, it can become a lithium composite oxide with less oxygen deficiency, and the cathode material has a high tap density.

[0072] In some embodiments of the present invention, preferably, the cathode material is prepared by the following method: in an oxygen-containing atmosphere, when the precursor does not contain the doping element M, mixing the precursor, a lithium source and an M source and performing the sintering to obtain the cathode material; or when the precursor contains the doping element M, mixing the precursor and a lithium source and performing the sintering to obtain the cathode material; wherein, M in the M source is selected from at least one non-Co element.

[0073] In the present invention, the doping element M can be added during the preparation of the precursor or during the preparation of the cathode material. Preferably, when the doping element M is added during the preparation of the precursor, the M source is selected from soluble compounds; when the doping element M is added during the preparation of the cathode material, the M source is selected from oxides.

[0074] In a specific embodiment of the present invention, the lithium source includes, but is not limited to, lithium oxide, lithium hydroxide, etc.

[0075] In some embodiments of the present invention, preferably, the dosage ratio of the lithium source satisfies: 0.9 ≤ [n(Li)] / [n(Ni)+n(Mn)+n(M)] ≤ 1.2. For example, 0.9, 1, 1.01, 1.02, 1.05, 1.06, 1.1, 1.15, 1.2, and any value within the range composed of any two of these values. Further preferably, it satisfies: 1 ≤ [n(Li)] / [n(Ni)+n(Mn)+n(M)] ≤ 1.1, and more preferably satisfies: 1.01 ≤ [n(Li)] / [n(Ni)+n(Mn)+n(M)] ≤ 1.06.

[0076] In the present invention, without special instructions, the M source follows the above limitations, and the present invention will not elaborate here.

[0077] In some embodiments of the present invention, preferably, the dosage of the M source satisfies: 0 ≤ [n(M)] / [n(Ni)+n(Mn)+n(M)] ≤ 0.1. For example, 0, 0.001, 0.002, 0.005, 0.008, 0.01, 0.05, 0.1, and any value within the range composed of any two of these values. Further preferably, it satisfies: 0.001 ≤ [n(M)] / [n(Ni)+n(Mn)+n(M)] ≤ 0.1, and more preferably satisfies: 0.001 ≤ [n(M)] / [n(Ni)+n(Mn)+n(M)] ≤ 0.01.

[0078] In some embodiments of the present invention, preferably, M in the M source is selected from at least one element of Al, Fe, Mg, B, Ca, Sr, Ba, Zr, Ti, Ce, Y, W, La, Nb, Ta, Zn, Co, and Mo, and is preferably selected from at least one element of La, Cr, Mo, Hf, Ti, Zn, Y, Zr, W, Nb, V, Mg, B, Y, and Al.

[0079] In some embodiments of the present invention, preferably, the oxygen content in the oxygen-containing atmosphere is ≥ 80% by volume, preferably ≥ 95% by volume.

[0080] In some embodiments of the present invention, preferably, the sintering conditions include: temperature is 600 - 900 °C, preferably 700 - 800 °C; time is 0.1 - 20 h, preferably 0.1 - 15 h; heating rate is 1 - 20 °C / min, preferably 1 - 5 °C / min.

[0081] In some embodiments of the present invention, preferably, the positive electrode material has the composition shown in Formula II, Li 1+ a Ni α Mn β M γ O 2 (II);

[0082] wherein, -0.1 ≤ a ≤ 0.2, 0.8 ≤ α < 1, 0 < β ≤ 0.2, 0 ≤ γ ≤ 0.1, and α + β + γ = 1; M is at least one non-Co element.

[0083] In some embodiments of the present invention, further preferably, in Formula II, 0 ≤ a ≤ 0.1, 0.85 ≤ α ≤ 0.99, 0.01 ≤ β ≤ 0.15, 0.001 ≤ γ ≤ 0.1, and α + β + γ = 1; M is selected from at least one element of La, Cr, Mo, Ca, Fe, Hf, Ti, Zn, Y, Zr, Si, W, Nb, Sm, V, Mg, B, Y, and Al.

[0084] In some embodiments of the present invention, more preferably, in Formula II, 0.01 ≤ a ≤ 0.06, 0.9 ≤ α ≤ 0.98, 0.02 ≤ β ≤ 0.1, 0.001 ≤ γ ≤ 0.01, and α + β + γ = 1; M is selected from at least one element of La, Cr, Mo, Hf, Ti, Zn, Y, Zr, W, Nb, V, Mg, B, Y, and Al.

[0085] In some embodiments of the present invention, preferably, the tap density of the positive electrode material ≥ 2.5 g / cm 3 , for example, 2.5 g / cm 3 , 2.6 g / cm 3 , 2.7 g / cm 3 , 2.8 g / cm 3 , 2.9 g / cm 3 , 3 g / cm 3 , and any value within the range composed of any two numerical values, preferably 2.5 - 3 g / cm 3 .

[0086] In some embodiments of the present invention, preferably, the positive electrode material has a layered structure.

[0087] The fifth aspect of the present invention provides a lithium-ion battery, which contains the cathode material provided in the fourth aspect.

[0088] The present invention will be described in detail below through examples.

[0089] The process parameters for preparing the precursor and the cathode material in the examples and comparative examples are listed in Table 1, and the physical property parameters of the precursors and cathode materials prepared in the examples and comparative examples are listed in Table 2.

[0090] Example 1

[0091] (1) Based on the metal elements, NiSO 4 ·6H 2 O and MnSO 4 ·H 2 O were dissolved in water at a molar ratio of 95:5 to prepare a 2 mol / L mixed salt solution; an 8 mol / L sodium hydroxide solution was prepared as a precipitant, and a 10 mol / L ammonia water was prepared as a complexing agent;

[0092] (2) Deionized water was added to a 5 L reactor to submerge the upper stirring paddle. The temperature of the reactor was controlled at 65 °C, and the stirring speed was set at 770 rpm. The above ammonia water and sodium hydroxide solution were added to the reactor to adjust the bottom liquid, so that the ammonia concentration in the reactor was adjusted to 3 g / L and the pH value was adjusted to 11. Nitrogen was introduced into the reactor at a flow rate of 20 L / h, and the oxygen content in the reactor was 5 vol%.

[0093] (3) The above mixed salt solution, sodium hydroxide aqueous solution and ammonia water were added to the reactor by a metering pump. The inlet flow rate of the mixed salt solution was set at 190 mL / h, and the inlet flow rates of the sodium hydroxide solution and ammonia water were automatically adjusted according to the pH value and ammonia concentration for coprecipitation reaction. During the reaction process, the particle size of the slurry was measured with a laser particle size analyzer every 2 h, and the pH value in the reactor was adjusted to keep the pH in the range of 11 ± 0.1;

[0094] (4) After the particle size D 50 grew to 14 μm, the liquid feeding was stopped. The obtained coprecipitation reaction product was alternately washed with 0.2 mol / L sodium hydroxide solution and water at 75 °C, and then dried at 120 °C for 3 h to obtain a precursor S1 with the general formula Ni 0.95 Mn 0.05 (OH) 2 ;

[0095] (5) In an oxygen-containing atmosphere (oxygen content is 95 vol%), the above precursor S1, lithium source (lithium hydroxide) and M source (TiO 2 ) were mixed and heated to 800 °C at a rate of 3 °C / min for sintering for 12 h, and then cooled to room temperature to obtain a general formula of Li1.02 Ni 0.945 Mn 0.05 Ti 0.005 O 2 The positive electrode material P1 of

[0096] Among them, the dosage ratio of the lithium source satisfies: [n(Li)] / [n(Ni)+n(Mn)+n(M)] = 1.02; the dosage of the M source satisfies: [n(M)] / [n(Ni)+n(Mn)+n(M)] = 0.005;

[0097] Among them, the SEM diagram of the above-mentioned precursor S1 is shown in Figure 1. It can be seen from Figure 1 that the precursor S1 is a secondary particle composed of primary particles. The primary particle is an elongated wedge-shaped structure, and the secondary particle has a spherical structure;

[0098] Among them, the XRD diagram of the above-mentioned precursor S1 is as Figure 2 shown. It can be seen from Figure 2 that the precursor S1 has characteristic double peaks of the 001 crystal plane in the range of 2θ = 18.7 ± 1.5°.

[0099] Example 2

[0100] (1) Calculated by metal elements, dissolve NiSO 4 ·6H 2 O and MnSO 4 ·H 2 O in water at a molar ratio of 90:10 to prepare a 1.5 mol / L mixed salt solution; prepare a 4 mol / L sodium hydroxide solution as a precipitant and a 10 mol / L ammonia water as a complexing agent;

[0101] (2) Add deionized water to the 5 L reactor to submerge the upper stirring paddle. Control the temperature of the reactor at 55 °C and set the stirring speed to 500 rpm; add the above ammonia water and sodium hydroxide solution to the reactor to adjust the bottom liquid, so that the ammonia concentration in the reactor is adjusted to 7 g / L and the pH value is adjusted to 10.8. Nitrogen is introduced into the reactor at a nitrogen flow rate of 100 L / h, and the oxygen content in the reactor is 0.5 vol%;

[0102] (3) Use a metering pump to add the above mixed salt solution, sodium hydroxide aqueous solution and ammonia water to the reactor through the metering pump. Set the inlet flow rate of the mixed salt solution to 100 mL / h, and the inlet flow rates of the sodium hydroxide solution and ammonia water are automatically adjusted according to the pH value and ammonia concentration for coprecipitation reaction. During the reaction process, use a laser particle size analyzer to test the particle size of the slurry every 2 h. By adjusting the pH value in the reactor, keep the pH in the reactor within the range of 10.8 ± 0.1;

[0103] (4) Wait until the particle size D 50After the liquid feeding is stopped when it grows to 10 μm, the obtained coprecipitation reaction product is washed alternately with 0.2 mol / L sodium hydroxide solution at 75 °C and water, and then dried at 120 °C for 3 h to obtain a precursor S2 with the general formula Ni 0.9 Mn 0.1 (OH) 2 ;

[0104] (5) In an oxygen-containing atmosphere (oxygen content is 95% by volume), the above precursor S2, lithium source (lithium hydroxide), and M source (TiO 2 ) are mixed, and heated to 800 °C at a rate of 3 °C / min and sintered for 12 h, then cooled to room temperature to obtain a cathode material P1 with the general formula Li 1.02 Ni 0.896 Mn 0.099 Ti 0.005 O 2 ;

[0105] Among them, the dosage ratio of the lithium source satisfies: [n(Li)] / [n(Ni)+n(Mn)+n(M)] = 1.02; the dosage of the M source satisfies: [n(M)] / [n(Ni)+n(Mn)+n(M)] = 0.005.

[0106] Among them, the SEM image of the above precursor S2 is shown in Figure 3. It can be seen from Figure 3 that the precursor S2 is a secondary particle composed of primary particles. The primary particle is an elongated wedge-shaped structure, and the secondary particle has a spherical structure;

[0107] Among them, the XRD pattern of the above precursor S2 is as Figure 4 shown. It can be seen from Figure 4 that the precursor S2 has characteristic double peaks of the 001 crystal plane in the range of 2θ = 19.5 ± 1°.

[0108] Example 3

[0109] (1) Calculated based on metal elements, NiSO 4 ·6H 2 O and MnSO 4 ·H 2 O are dissolved in water at a molar ratio of 98:2 to prepare a 1.5 mol / L mixed salt solution; an 8 mol / L sodium hydroxide solution is prepared as a precipitant, and a 5 mol / L ammonia water is prepared as a complexing agent;

[0110] (2) Add deionized water to the 5 L reactor to submerge the upper stirring paddle. Control the temperature of the reactor at 75 °C and set the stirring speed to 700 rpm. Add the above ammonia water and sodium hydroxide solution to the reactor to adjust the bottom liquid, so that the ammonia concentration in the reactor is adjusted to 11 g / L and the pH value is adjusted to 10.3. Nitrogen is introduced into the reactor at a flow rate of 10 L / h, and the oxygen content in the reactor is 8 vol%.

[0111] (3) Use a metering pump to add the above mixed salt solution, aqueous sodium hydroxide solution and ammonia water to the reactor through the metering pump. Set the inlet flow rate of the mixed salt solution to 240 mL / h, and the inlet flow rates of the sodium hydroxide solution and ammonia water are automatically adjusted according to the pH value and ammonia concentration for coprecipitation reaction. During the reaction process, the particle size of the slurry is tested with a laser particle size analyzer every 2 h. By adjusting the pH value in the reactor, keep the pH in the reactor within the range of 10.3 ± 0.1.

[0112] (4) After the particle size D 50 grows to 12 μm, stop the inlet of the liquid. Wash the obtained coprecipitation reaction product alternately with 0.2 mol / L sodium hydroxide solution at 75 °C and water, and then dry it at 120 °C for 3 h to obtain the precursor S3 with the general formula Ni 0.98 Mn 0.02 (OH) 2 .

[0113] (5) In an oxygen-containing atmosphere (oxygen content is 95 vol%), mix the above precursor S3, lithium source (lithium hydroxide) and M source (TiO 2 ), and heat it to 800 °C at a rate of 3 °C / min for sintering for 12 h, and then cool it to room temperature to obtain the cathode material P3 with the general formula Li 1.02 Ni 0.975 Mn 0.02 Ti 0.005 O 2 .

[0114] Among them, the dosage ratio of the lithium source satisfies: [n(Li)] / [n(Ni)+n(Mn)+n(M)] = 1.02; the dosage of the M source satisfies: [n(M)] / [n(Ni)+n(Mn)+n(M)] = 0.005.

[0115] Among them, the SEM image of the above precursor S3 is shown in Figure 5. It can be seen from Figure 5 that the precursor S3 is a secondary particle composed of primary particles. The primary particle is an elongated wedge-shaped structure, and the secondary particle has a spherical structure.

[0116] Among them, the XRD pattern of the above precursor S3 is as shown in Figure 6 . It can be seen from Figure 6 that the precursor S3 has characteristic double peaks of the 001 crystal plane in the range of 2θ = 19.4 ± 1°.

[0117] Example 4

[0118] (1) Based on the metal element, NiSO 4 ·6H 2 O and MnSO 4 ·H 2 O were dissolved in water at a molar ratio of 95:5 to prepare a 1.5 mol / L mixed salt solution; 8 mol / L sodium hydroxide solution was prepared as a precipitant, and 5 mol / L ammonia water was prepared as a complexing agent;

[0119] (2) Deionized water was added to a 5 L reactor to submerge the upper stirring paddle. The temperature of the reactor was controlled at 75 °C, and the stirring speed was set at 700 rpm. The above ammonia water and sodium hydroxide solution were added to the reactor to adjust the bottom liquid, so that the ammonia concentration in the reactor was adjusted to 11 g / L and the pH value was adjusted to 10.5. Nitrogen was introduced into the reactor at a flow rate of 50 L / h, and the oxygen content in the reactor was 2.5 vol%;

[0120] (3) The above mixed salt solution, sodium hydroxide aqueous solution and ammonia water were added to the reactor by a metering pump. The inlet flow rate of the mixed salt solution was set at 240 mL / h, and the inlet flow rates of the sodium hydroxide solution and ammonia water were automatically adjusted according to the pH value and ammonia concentration for coprecipitation reaction. During the reaction process, the particle size of the slurry was measured every 2 h with a laser particle size analyzer. By adjusting the pH value in the reactor, the pH in the reactor was maintained within the range of 10.5 ± 0.1;

[0121] (4) After the particle size D 50 grew to 8 μm, the liquid feeding was stopped. The obtained coprecipitation reaction product was alternately washed with 0.2 mol / L sodium hydroxide solution at 75 °C and water, and then dried at 120 °C for 3 h to obtain a precursor S4 with the general formula Ni 0.95 Mn 0.5 (OH) 2 ;

[0122] Among them, the above precursor S4 is a secondary particle composed of primary particles. The primary particle is an elongated wedge-shaped structure, and the secondary particle has a spherical structure; among them, the above precursor S4 has characteristic double peaks of the 001 crystal plane in the range of 2θ at 18.7 ± 1°;

[0123] (5) In an oxygen-containing atmosphere (oxygen content is 95 vol%), the above precursor S4, lithium source (lithium hydroxide) and M source (TiO 2 ) were mixed and heated to 800 °C at a rate of 3 °C / min for sintering for 12 h, and then cooled to room temperature to obtain a product with the general formula Li 1.02 Ni 0.945 Mn 0.05 Ti0.005 O 2 The positive electrode material P4 of

[0124] Among them, the dosage ratio of the lithium source satisfies: [n(Li)] / [n(Ni)+n(Mn)+n(M)] = 1.02; the dosage of the M source satisfies: [n(M)] / [n(Ni)+n(Mn)+n(M)] = 0.005.

[0125] Example 5

[0126] (1) Based on metal elements, dissolve NiSO 4 ·6H 2 O, MnSO 4 ·H 2 O, and TiOSO 4 in water at a molar ratio of 90:9.5:0.5 to prepare a 1.7 mol / L mixed salt solution; prepare an 8 mol / L sodium hydroxide solution as a precipitant and a 5 mol / L ammonia water as a complexing agent;

[0127] (2) Add deionized water to a 5 L reactor to submerge the upper stirring paddle, control the reactor temperature at 75 °C, and set the stirring speed to 700 rpm; add the above ammonia water and sodium hydroxide solution to the reactor to adjust the bottom liquid, so that the ammonia concentration in the reactor is adjusted to 5 g / L and the pH value is adjusted to 10.8. Nitrogen is introduced into the reactor at a flow rate of 50 L / h, and the oxygen content in the reactor is 2.5 vol%;

[0128] (3) Use a metering pump to add the above mixed salt solution, sodium hydroxide aqueous solution and ammonia water to the reactor through the metering pump. The inlet flow rate of the mixed salt solution is set to 240 mL / h, and the inlet flow rates of the sodium hydroxide solution and ammonia water are automatically adjusted according to the pH value and ammonia concentration for coprecipitation reaction. During the reaction process, the particle size of the slurry is tested with a laser particle size analyzer every 2 h, and the pH value in the reactor is adjusted to keep the pH in the range of 10.8 ± 0.1;

[0129] (4) After the particle size D 50 grows to 10 μm, stop the liquid feeding. Wash the obtained coprecipitation reaction product alternately with 0.2 mol / L sodium hydroxide solution at 75 °C and water, and then dry it at 120 °C for 3 h to obtain a precursor S5 with the general formula Ni 0.9 Mn 0.095 Ti 0.005 (OH) 2 ;

[0130] Among them, the above precursor S5 is a secondary particle composed of primary particles. The primary particle is an elongated wedge-shaped structure, and the secondary particle has a spherical structure. Among them, the above precursor S5 has characteristic double peaks of the 001 crystal plane in the range of 2θ at 18.7 ± 1°.

[0131] (5) In an oxygen-containing atmosphere (oxygen content is 95% by volume), the above precursor S5 and a lithium source (lithium hydroxide) are mixed, and heated to 800 °C at a rate of 3 °C / min and sintered for 12 h, then cooled to room temperature to obtain a cathode material P5 with the general formula Li 1.02 Ni 0.9 Mn 0.095 Ti 0.005 O 2 ;

[0132] Among them, the dosage ratio of the lithium source satisfies: [n(Li)] / [n(Ni) + n(Mn) + n(M)] = 1.02.

[0133] Example 6

[0134] According to the method of Example 1, the difference is that

[0135] In step (1), an M source is added. Calculated as metal elements, the molar ratio of NiSO 4 ·6H 2 O, MnSO 4 ·H 2 O, and TiOSO 4 is replaced with 94.5:5:0.5, and the pH value is controlled within the range of 11 ± 0.1, and the remaining conditions are the same, to obtain a precursor S6 and a cathode material P6.

[0136] Example 7

[0137] According to the method of Example 1, the difference is that

[0138] In step (1), an M source is added. Calculated as metal elements, the molar ratio of NiSO 4 ·6H 2 O, MnSO 4 ·H 2 O, and Y 2 O 3 is replaced with 94.5:5:0.5, and the pH value is controlled within the range of 11 ± 0.1, and the remaining conditions are the same, to obtain a precursor S7 and a cathode material P7.

[0139] Comparative Example 1

[0140] According to the method of Example 1, the difference is that

[0141] In step (2), the nitrogen gas flow rate was adjusted to 100 L / h, so that the oxygen content in the reaction kettle was 0.5 vol%, the pH was controlled in the range of 11.6 ± 0.1, and the other conditions were the same, to obtain a precursor DS1 with the general formula Ni 0.95 Mn 0.5 (OH) 2 and a cathode material DP1 with the general formula Li 1.02 Ni 0.945 Mn 0.05 Ti 0.005 O 2 .

[0142] Among them, the SEM image of the above-mentioned precursor DS1 is shown in Figure 7. It can be seen from Figure 7 that the precursor DS1 is a secondary particle composed of primary particles. The primary particle is an elongated wedge-shaped structure, and the secondary particle has a spherical structure;

[0143] Among them, the XRD pattern of the above-mentioned precursor DS1 is as Figure 8 shown. It can be seen from Figure 8 that the diffraction peak of the precursor DS1 on the 001 crystal plane is a single peak.

[0144] Comparative Example 2

[0145] According to the method of Example 1, the difference is that

[0146] in step (2), compressed air was introduced, and the oxygen content in the reaction kettle was controlled to be 16 vol%, and the other conditions were the same, to obtain a precursor DS2 with the general formula Ni 0.95 Mn 0.5 (OH) 2 and a cathode material DP2 with the general formula Li 1.02 Ni 0.945 Mn 0.05 Ti 0.005 O 2 .

[0147] Comparative Example 3

[0148] According to the method of Example 1, the difference is that

[0149] in step (5), the type of M source was replaced with CoSO 4 , and the other conditions were the same, to obtain a cathode material DS3.

[0150] Table 1

[0151]

[0152]

[0153] Note: 1 - Inlet flow rate of the mixed salt solution, mL / h.

[0154] Continued Table 1

[0155]

[0156]

[0157] Table 2

[0158]

[0159] Note: * - 2θ has characteristic double peaks of the 001 crystal plane within the range of 19 ± 1.5°.

[0160] Continued Table 2

[0161]

[0162] Continued Table 2

[0163]

[0164] Note: 2 - K 90 =(D 90 - D 10 ) / D 50 , D 90 , D 10 and D 50 respectively refer to the particle sizes of the precursor with cumulative volume values of 90%, 10%, and 50% in the particle size distribution, and the unit is μm.

[0165] Continued Table 2

[0166]

[0167] From the data in Tables 1 - 2, it can be seen that compared with Comparative Examples 1 - 3, in Examples 1 - 7, by regulating the oxygen content in the reaction system to be 0.5 - 10 vol% and the pH value to be 10 - 11.3, the prepared precursors S1 - S7 all have XRD diffraction 001 double peaks and satisfy 1.5 ≤ I (101) / I (001) ≤ 3, improving the particle crystallinity, thereby enhancing the crystallinity of the precursor, so that the positive electrode material prepared by sintering the above - mentioned precursor has a higher tap density on the premise of meeting the structural stability.

[0168] At the same time, the precursors prepared in Examples 1 - 7 further define that the characteristic double peaks of the 001 crystal plane include single peak A and single peak B, and define the full - width at half - maximum, peak intensity, and peak area parameters of single peak A and single peak B, making the precursor have the characteristics of a large BET, a high tap density, and a narrow particle size distribution.

[0169] Test Example

[0170] The positive electrode materials prepared in the examples and comparative examples were subjected to electrochemical performance tests.

[0171] Battery assembly: The above positive electrode material, conductive carbon black, and polyvinylidene fluoride (PVDF) were weighed separately according to a mass ratio of 95:2.5:2.5 and mixed. NMP was added and stirred to form a homogeneous slurry. The slurry was coated on an aluminum foil, leveled, dried, and then rolled flat. It was stamped into a positive electrode sheet with a diameter of 12 mm and a thickness of 120 μm under a pressure of 100 MPa, and then placed in a vacuum oven and dried at 120 °C for 12 h to obtain the positive electrode sheet.

[0172] The coin cell assembly process was carried out in a glove box protected by Ar gas, where the water content and oxygen content were both less than 5 ppm; the positive electrode used the above-obtained electrode sheet, the negative electrode used a Li metal sheet with a diameter of 17 mm and a thickness of 1 mm; the separator used a polyethylene porous membrane with a thickness of 25 μm, the electrolyte used an equal mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) dissolved with 1 mol / L of LiPF6, and the battery case used a coin cell case of model 2025. After assembly, an unactivated battery was obtained.

[0173] The performance of the assembled lithium-ion battery was tested, and the test results are shown in Table 3 respectively. Among them, the charging capacity of the lithium-ion battery was measured by taking the coin cell after standing for 2 h after assembly and performing constant current charging at 0.1C (1C = 200 mA / g) to the cut-off voltage of 4.3V at room temperature, and then performing constant voltage charging for 30 min;

[0174] The discharge capacity was measured by discharging the above-charged coin cell at a constant current of 0.1C to 3.0V at room temperature;

[0175] The first efficiency was measured by dividing the 0.1C discharge capacity by the 0.1C charging capacity;

[0176] The rate performance of 1C / 0.1C was measured by, at room temperature, performing constant current charge and discharge on the above coin cell that had completed one 0.1C charge and discharge cycle successively at 0.2C, 0.33C, 0.5C, and 1C, with a voltage window of 4.3 - 3.0V, and then dividing the 1C discharge capacity by the 0.1C discharge capacity;

[0177] The 80-week cycle retention rate was measured by taking the coin cell that had completed one 0.1C charge and discharge cycle, performing constant current charge and discharge at 1C for 80 cycles at room temperature, with a voltage window of 4.3 - 3.0V, and dividing the discharge capacity of the 80th week by the discharge capacity of the 1st week.

[0178] Table 3

[0179]

[0180] It can be seen from the data in Table 3 that, compared with Comparative Examples 1-3, the lithium-ion batteries assembled with the cathode materials prepared in Examples 1-7 have higher capacity performance, rate performance and cycling performance.

[0181] 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 technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A nickel-manganese binary precursor, characterized in that, The precursor has a composition shown in Formula I, Ni x Mn y M z (OH) 2 (I), 0.8 ≤ x < 1, 0 < y ≤ 0.2, 0 ≤ z ≤ 0.1, and x + y + z = 1, M is selected from at least one non-Co element; the precursor is a secondary particle composed of primary particles, and the primary particle has a wedge-shaped structure; Among them, the precursor uses CuK α In the powder X-ray diffraction measurement using θ rays, there are characteristic double peaks of the 001 crystal plane within the range of 19 ± 1.5°; Among them, the precursor uses CuK α In the powder X-ray diffraction measurement using CuK (101) / I (001) ≥ 1.5, and the characteristic peak of the 101 crystal plane 2 θ is in the range of (37 - 41)°.

2. The precursor according to claim 1, wherein, In formula I, 0.85 ≤ x ≤ 0.99, 0.01 ≤ y ≤ 0.15, 0 ≤ z ≤ 0.1, and x + y + z = 1, and M is selected from at least one element among La, Cr, Mo, Ca, Fe, Hf, Ti, Zn, Y, Zr, Si, W, Nb, Sm, V, Mg, B, and Al.

3. The precursor according to claim 2, wherein, In formula I, 0.9 ≤ x ≤ 0.98, 0.02 ≤ y ≤ 0.1, 0 ≤ z ≤ 0.01, and x + y + z = 1, and M is selected from at least one element among La, Cr, Mo, Hf, Ti, Zn, Y, Zr, W, Nb, V, Mg, B, and Al.

4. The precursor according to claim 1, wherein, 1.5 ≤ I (101) / I (001) ≤ 3.

5. The precursor according to claim 1, wherein, The peak intensity I of the characteristic double peaks of the 001 crystal plane (001) is 300 - 4000, and the full width at half maximum FWHM (001) is (0.5 - 2)°.

6. The precursor according to claim 5, wherein, The peak intensity I of the characteristic double peaks of the 001 crystal plane (001) is 500 - 3000, and the full width at half maximum FWHM (001) is (0.6 - 1.8)°.

7. The precursor according to claim 1, wherein, The characteristic double peaks of the 001 crystal plane include single peak A and single peak B, and single peak A is located to the left of single peak B; The peak intensities of the unimodal peak A and the unimodal peak B satisfy: 500 ≤ I (A) ≤ 2000, 600 ≤ I (B) ≤ 2000, 0.35 ≤ I (A) / I (B) ≤ 2.4; The full width at half maximum (FWHM) of the single peak A and the single peak B satisfies: 0.4° ≤ FWHM (A) ≤ 0.7°, 0.4° ≤ FWHM (B) ≤ 0.6°, 0.7 ≤ FWHM (A) / FWHM (B) ≤ 1.5; The peak areas of the unimodal peak A and the unimodal peak B satisfy: 10000 ≤ A (A) ≤ 70000, 10000 ≤ A (B) ≤ 75000, 0.6 ≤ A (A) / A (B) ≤ 2.

2.

8. The precursor according to any one of claims 1-7, wherein, The precursor has a spherical structure; and / or, the BET of the precursor is 3-25 m 2 / g; the tapped density is ≥1 g / cm 3 ; and / or, the particle size distribution K of the precursor 90 satisfies: 0.4 ≤ K 90 ≤ 0.8, where K 90 = (D 90 - D 10 ) / D 50 , D 90 , D 10 and D 50 respectively refer to the particle diameters at which the cumulative volume fractions of the precursor in the particle size distribution are 90%, 10% and 50% respectively, and the unit is μm; and / or, D of the precursor 50 is 6 - 20 μm.

9. The precursor according to claim 8, wherein, The BET of the precursor is 5-20 m 2 / g; the tapped density is 1.3-2.5 g / cm 3 ; and / or, D of the precursor 50 is 8 - 14 μm.

10. A preparation method of the nickel-manganese binary precursor according to any one of claims 1-9, characterized in that, The preparation method includes: mixing a mixed salt solution, a complexing agent, and a precipitating agent and performing a coprecipitation reaction, controlling the oxygen content in the reaction system to be 0.5-10% by volume and the pH value to be 10-11.3, and successively washing and drying the obtained coprecipitation reaction product to obtain the precursor; wherein, the mixed salt solution is selected from an aqueous solution containing a nickel salt, a manganese salt, and an optional M source, and M in the M source is selected from at least one non-Co element.

11. The preparation method according to claim 10, wherein, Controlling the oxygen content in the reaction system to be 0.5-8% by volume; and / or, when the complexing agent is selected from a compound containing an ammonium ion, controlling the ammonia concentration in the reaction system to be 1-12 g / L; and / or, the conditions of the coprecipitation reaction include: temperature is 50-80 °C, pH value is 10-11.3; rotation speed is 250-750 rpm; and / or, based on the metal element, the nickel salt, the manganese salt, and the M source satisfy n(Ni):n(Mn):n(M), 0.8 ≤ n(Ni) < 1, 0 < n(Mn) ≤ 0.2, 0 ≤ n(M) ≤ 0.1; and / or, M in the M source is selected from at least one element among La, Cr, Mo, Ca, Fe, Hf, Ti, Zn, Y, Zr, Si, W, Nb, Sm, V, Mg, B, and Al; and / or, the feeding flow rate of the mixed salt solution is 50-300 mL / min; and / or, the washing process includes: alternately washing the coprecipitation reaction product with alkali and water; and / or, the drying conditions include: temperature is 80-150 °C, time is 2-6 h.

12. The preparation method according to claim 11, wherein, when the complexing agent is selected from compounds containing ammonium ions, the ammonia concentration in the reaction system is adjusted to 3 - 8 g / L; and / or, the conditions for the coprecipitation reaction include: the pH value is 10.3 - 11.1; and / or, based on metal elements, the nickel salt, manganese salt, and M source satisfy n(Ni):n(Mn):n(M), where 0.85 ≤ n(Ni) ≤ 0.99, 0.01 ≤ n(Mn) ≤ 0.15, and 0 ≤ n(M) ≤ 0.1; and / or, M in the M source is selected from at least one element among La, Cr, Mo, Hf, Ti, Zn, Y, Zr, W, Nb, V, Mg, B, and Al; and / or, the feeding flow rate of the mixed salt solution is 150 - 250 mL / min.

13. The preparation method according to claim 12, wherein, based on metal elements, the nickel salt, manganese salt, and M source satisfy n(Ni):n(Mn):n(M), where 0.9 ≤ n(Ni) ≤ 0.98, 0.02 ≤ n(Mn) ≤ 0.1, and 0 ≤ n(M) ≤ 0.

01.

14. Application of the precursor according to any one of claims 1 - 9 in a cathode material.

15. A cathode material, characterized in that, the cathode material is prepared by sintering the precursor according to any one of claims 1 - 9.

16. The cathode material according to claim 15, wherein, the cathode material is prepared by the following method: in an oxygen-containing atmosphere, when the precursor does not contain the doping element M, the precursor, lithium source, and M source are mixed and sintered to obtain the cathode material; or, when the precursor contains the doping element M, the precursor and lithium source are mixed and sintered to obtain the cathode material; wherein, M in the M source is selected from at least one non-Co element.

17. The cathode material according to claim 16, wherein, the dosage ratio of the lithium source satisfies: 0.9 ≤ [n(Li)] / [n(Ni)+n(Mn)+n(M)] ≤ 1.2; and / or, the dosage of the M source satisfies: 0 ≤ [n(M)] / [n(Ni)+n(Mn)+n(M)] ≤ 0.1; and / or, the M source is selected from at least one element among Al, Fe, Mg, B, Ca, Cr, Hf, Si, Sm, V, Zr, Ti, Y, W, La, Nb, Zn, and Mo.

18. The cathode material according to claim 17, wherein, the dosage ratio of the lithium source satisfies: 1 ≤ [n(Li)] / [n(Ni)+n(Mn)+n(M)] ≤ 1.1; and / or, the M source is selected from at least one element among La, Cr, Mo, Hf, Ti, Zn, Y, Zr, W, Nb, V, Mg, B, and Al.

19. The cathode material according to claim 18, wherein, the dosage ratio of the lithium source satisfies: 1.01 ≤ [n(Li)] / [n(Ni)+n(Mn)+n(M)] ≤ 1.06; And / or, the dosage of the M source satisfies: 0 ≤ [n(M)] / [n(Ni) + n(Mn) + n(M)] ≤ 0.

01.

20. The positive electrode material according to claim 16, wherein, the oxygen content in the oxygen-containing atmosphere is ≥ 80% by volume; and / or, the sintering conditions include: the temperature is 600 - 900 °C; the time is 0.1 - 20 h; the heating rate is 1 - 20 °C / min.

21. The positive electrode material according to claim 20, wherein, the oxygen content in the oxygen-containing atmosphere is ≥ 95% by volume; and / or, the sintering conditions include: the temperature is 700 - 800 °C; the time is 0.1 - 15 h; the heating rate is 1 - 5 °C / min.

22. The positive electrode material according to claim 15, wherein, The positive electrode material has a composition represented by Formula II, Li 1+ a Ni α Mn β M γ O 2 (II); where, -0.1 ≤ a ≤ 0.2, 0.8 ≤ α < 1, 0 < β ≤ 0.2, 0 ≤ γ ≤ 0.1, and α + β + γ = 1; M is selected from at least one non-Co element.

23. The positive electrode material according to claim 22, wherein, In formula II, 0 ≤ a ≤ 0.1, 0.85 ≤ α ≤ 0.99, 0.01 ≤ β ≤ 0.15, 0 ≤ γ ≤ 0.1, and α + β + γ = 1; M is selected from at least one element of La, Cr, Mo, Ca, Fe, Hf, Ti, Zn, Y, Zr, Si, W, Nb, Sm, V, Mg, B, and Al.

24. The positive electrode material according to claim 23, wherein, In formula II, 0.01 ≤ a ≤ 0.06, 0.9 ≤ α ≤ 0.98, 0.02 ≤ β ≤ 0.1, 0 ≤ γ ≤ 0.01, and α + β + γ = 1; M is selected from at least one element of La, Cr, Mo, Hf, Ti, Zn, Y, Zr, W, Nb, V, Mg, B, and Al.

25. The positive electrode material according to any one of claims 15 - 24, wherein, The tap density of the positive electrode material is ≥ 2.5 g / cm 3 ; and / or, the positive electrode material has a layered structure.

26. The positive electrode material according to claim 25, wherein, The tap density of the positive electrode material is 2.5 - 3 g / cm 3 .

27. A lithium-ion battery, characterized in that the lithium-ion battery contains the positive electrode material according to any one of claims 15 - 26.

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