A high-nickel positive electrode material and a preparation method and application thereof

Abstract

The application discloses a high-nickel positive electrode material and a preparation method and application thereof, and belongs to the technical field of new energy sources. x Co y M z M´ w O2 and a porous base material and a gap-filling substance, wherein 0.80<=x<=0.98, 0.02<=y<=0.20, 0<=z<=0.06, 0<w<=0.02; x+y+z+w=1; M is at least one of Mn and Al, M´ is at least one of Y, Sr, La, B, Mg and Ti; the gap-filling substance exists in the inside of the pores and comprises a sintered product derived from an additive B, the additive B comprises a zirconium-containing compound and at least one of a tungsten-containing compound, an antimony-containing compound and a bismuth-containing compound. The high-nickel positive electrode material has excellent long cycle performance and rate performance. The application further provides a preparation method and application of the high-nickel positive electrode material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy, in particular to a high-nickel positive electrode material and a preparation method and application thereof. BACKGROUND

[0002] With the expansion and development of electric tools, unmanned aerial vehicles and other fields, the performance requirements of related equipment on lithium batteries are getting higher and higher, and lithium ion batteries need higher capacity and greater rate. Correspondingly, the positive electrode material is required to have higher capacity and better rate performance. Increasing the content of Ni is one of the effective methods to improve the capacity of the positive electrode material. When the molar amount of nickel in the layered metal oxide positive electrode material accounts for more than 80% of the molar amount of transition metals, it is called high-nickel material. On the basis of already having high capacity, it is particularly important to improve the cycle performance and rate performance of the high-nickel material.

[0003] In the industry, attempts have been made to use doping and coating modification, sintering and post-treatment optimization and other means to improve the stability of the high-nickel positive electrode material in order to improve its long cycle performance. However, the effect achieved by the traditional modification means is limited, and the cycle stability and high-rate performance of the high-nickel positive electrode material still need to be further improved. SUMMARY

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application provides a high-nickel positive electrode material, which has excellent structural stability and can effectively improve its long cycle performance and rate performance.

[0005] The present application also provides a preparation method of the high-nickel positive electrode material.

[0006] The present application also provides a lithium ion battery comprising the high-nickel positive electrode material.

[0007] According to an embodiment of the first aspect of the present application, a high-nickel positive electrode material is provided, which comprises:

[0008] a base material, the chemical general formula of the base material being LiNi x Co y M z M´ w O2, wherein 0.80≤x≤0.98, 0.02≤y≤0.20, 0≤z≤0.06, 0

[0009] a gap-filling substance, the gap-filling substance being present inside the pores, the gap-filling substance comprising a sintered product derived from an additive B,

[0010] The additive B includes a zirconium-containing compound, and at least one of a tungsten-containing compound, an antimony-containing compound, and a bismuth-containing compound.

[0011] The high-nickel positive electrode material according to the embodiments of the present application has at least the following beneficial effects:

[0012] Filling the interstitial substance in the pores of the base material is conducive to improving the mechanical properties and stability of the high-nickel positive electrode material.

[0013] The selection and combination of the additive B can synergistically improve the compaction degree of the interstitial substance, or can synergistically improve the uniformity of the interstitial substance, or can promote the penetration of each other into the pores; and overall, the comprehensive performance of the obtained high-nickel positive electrode material is improved.

[0014] In the selection of M´, Y is selected from Y 3+ -O 2 -Ni 4+ The electron cloud coupling mechanism inhibits the generation of oxygen defects and reduces the high-activity Ni 4+ concentration, thereby improving the structural stability and electrochemical performance of the high-nickel positive electrode material. Specifically, the rate capability, cycle performance, and high-temperature performance are significantly improved. The doping of Sr can effectively improve the structural stability of the high-nickel ternary positive electrode material. At the same time, the Sr-rich base material on the surface can effectively block the side reaction between the electrolyte and the internal part of the high-nickel positive electrode material, enhance the stability of the crystal structure on the surface of the primary particles, and prevent the degradation of the material crystal structure from the outside to the inside of the high-nickel positive electrode material. Mg, Ti, and the like can replace transition metals (Ni, Co, Mn) or Li sites, inhibit phase transition, reduce cation mixing, and enhance structural stability. The doping of B can partially replace O sites, enhance lattice stability, reduce oxygen release, and inhibit electrolyte decomposition. The doping of rare earth element La can effectively improve the thermal stability and cycle life of the material.

[0015] In summary, the high-nickel positive electrode material provided by the present application can effectively improve the structural stability, reduce the generation of surface side reactions, and improve the cycle performance. At the same time, due to the selection of the doping and interstitial substance, the lithium ion conductivity of the obtained high-nickel positive electrode material is significantly improved, and the rate capability is improved.

[0016] According to some embodiments of the present application, the base material LiNi x Co y M z M´ w O2, 0.80≤x≤0.98. For example, it can be 0.80, 0.82, 0.85, 0.88, 0.90, 0.92, 0.95, 0.98, or a range value composed of any two of the above point values.

[0017] According to some embodiments of the present application, the base material LiNi x Co y M z M´ w In LiNi0.8Co0.1M0.1O2, 0.02≤y≤0.15. For example, it can be specifically 0.02, 0.04, 0.06, 0.08, 0.09, 0.10, 0.12, 0.15, or a range value composed of any two of the above point values.

[0018] According to some embodiments of the present application, the base material LiNi x Co y M z M´ w In LiNi0.8Co0.1M0.1O2, 0.01≤z≤0.03. For example, it can be specifically 0.01, 0.02, 0.03, or a range value composed of any two of the above point values.

[0019] According to some embodiments of the present application, the base material LiNi x Co y M z M´ w In LiNi0.8Co0.1M0.1O2, 0≤w≤0.02, preferably 0≤w≤0.015, more preferably 0.001≤w≤0.01. For example, it can be specifically 0.002, 0.003, 0.004, 0.005, 0.008, 0.010, 0.015, or a range value composed of any two of the above point values.

[0020] When the doping amount of the doping element M´ is too small, it is not enough to stabilize the lattice and inhibit the side reaction; when the doping amount is too high, it is easy to cause slight deformation of the layered structure of the high-nickel positive electrode material, affecting the deintercalation path of lithium ions.

[0021] According to some embodiments of the present application, the base material LiNi x Co y M z M´ w In LiNi0.8Co0.1M0.1O2, M is Al.

[0022] According to some embodiments of the present application, the base material LiNi x Co y M z M´ w In LiNi0.8Co0.1M0.1O2, M´ is at least one of Y and Sr. Further specifically, M´ is a combination of Y and Sr; the molar ratio between Y and Sr is any molar ratio, for example, it can be specifically 0.1~0.9:0.1~0.9; further specifically, it can be 0.8~1.2:1.

[0023] According to some embodiments of the present application, the concentration of the target element introduced by the single additive B in the high-nickel positive electrode material is 0-5000 ppm; the concentration of the target element introduced by all additives B in the high-nickel positive electrode material is >0 ppm.

[0024] The target element is Zr, W, Sb, and Bi.

[0025] According to some embodiments of the present application, when the additive B includes a zirconium-containing compound, the concentration of the Zr element in the high-nickel positive electrode material derived from the additive B is 0-5000 ppm.

[0026] According to some embodiments of the present application, when the additive B includes a zirconium-containing compound, the concentration of the Zr element in the high-nickel positive electrode material derived from the additive B is 500-4000 ppm. For example, it can be specifically 500 ppm, 600 ppm, 800 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, 3500 ppm, 4000 ppm, or a range value composed of any two of the above point values.

[0027] According to some embodiments of the present application, when the additive B includes a tungsten-containing compound, the concentration of the W element in the high-nickel positive electrode material derived from the additive B is 0-5000 ppm.

[0028] According to some embodiments of the present application, when the additive B includes a tungsten-containing compound, the concentration of the W element in the high-nickel positive electrode material derived from the additive B is 500-5000 ppm. For example, it can be specifically 500 ppm, 600 ppm, 800 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, 3500 ppm, 4000 ppm, 4500 ppm, 5000 ppm, or a range value composed of any two of the above point values.

[0029] According to some embodiments of the present application, when the additive B includes a bismuth-containing compound, the concentration of the Bi element in the high-nickel positive electrode material derived from the additive B is 0-5000 ppm.

[0030] According to some embodiments of the present application, when the additive B includes a bismuth-containing compound, the concentration of the Bi element in the high-nickel positive electrode material derived from the additive B is 500-3000 ppm. For example, it can be specifically 500 ppm, 600 ppm, 800 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, or a range value composed of any two of the above point values.

[0031] According to some embodiments of the present application, when the additive B comprises the antimony-containing compound, the concentration of Sb element from the additive B in the high-nickel positive electrode material is 0-5000 ppm.

[0032] According to some embodiments of the present application, when the additive B comprises the antimony-containing compound, the concentration of Sb element from the additive B in the high-nickel positive electrode material is 500-3000 ppm. For example, it can be specifically 500 ppm, 600 ppm, 800 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, or a range value composed of any two of the above point values.

[0033] According to some embodiments of the present application, the base material is a secondary spherical material composed of primary particles arranged. Due to the interstitial substance and the subsequent coating substance, the overall morphology of the high-nickel positive electrode material will not be significantly affected, and therefore the high-nickel positive electrode material can also be regarded as a secondary spherical material (also known as a polycrystalline material).

[0034] According to some embodiments of the present application, the additive B is a combination of a zirconium-containing compound and a tungsten-containing compound.

[0035] According to some embodiments of the present application, the additive B is a combination of a zirconium-containing compound, a tungsten-containing compound, and an antimony-containing compound.

[0036] According to some embodiments of the present application, the additive B is a combination of a zirconium-containing compound, a tungsten-containing compound, and a bismuth-containing compound.

[0037] According to some embodiments of the present application, the zirconium-containing compound comprises at least one of zirconium oxide, zirconium hydroxide, zirconium fluoride, zirconium carbonate, zirconium chloride, and zirconium nitrate.

[0038] According to some embodiments of the present application, the tungsten-containing compound comprises at least one of tungstic acid, tungsten oxide (tungsten trioxide), tungsten hydroxide, tungsten hexafluoride, tungsten chloride, sodium tungstate, and potassium tungstate.

[0039] According to some embodiments of the present application, the antimony-containing compound comprises at least one of antimony trioxide, antimony pentoxide, antimony trichloride, and sodium antimonate.

[0040] According to some embodiments of the present application, the bismuth-containing compound comprises at least one of bismuth oxide, bismuth sulfate, and bismuth chloride.

[0041] According to some embodiments of the present application, the high-nickel positive electrode material further has a coating layer, and the coating layer comprises a sintered product derived from an additive C, and the additive C comprises an aluminum-containing compound and a titanium-containing compound.

[0042] According to some embodiments of the present application, the coating layer is wrapped on the surface of the high-nickel positive electrode material.

[0043] According to some embodiments of the present application, the aluminum-containing compound comprises at least one of aluminum oxide, aluminum hydroxide and aluminum fluoride.

[0044] According to some embodiments of the present application, the titanium-containing compound comprises at least one of titanium oxide and titanium chloride.

[0045] According to some embodiments of the present application, in the additive C, the mass ratio of the aluminum-containing compound and the titanium-containing compound is 1:0.5-4; for example, it can be specifically 1:0.8, 1:1, 1:2, 1:3, 1:4, or a range value composed of any two of the above point values.

[0046] According to some embodiments of the present application, the mass percentage of the coating layer in the high-nickel positive electrode material is greater than 0 and ≤4%; for example, it can be specifically 0.2%, 0.3%, 0.4%, 0.5%, 1%, 2%, 3%, 4%, or a range value composed of any two of the above point values.

[0047] According to some embodiments of the present application, the porosity inside the high-nickel positive electrode material is 0.2%-6%.

[0048] According to some embodiments of the present application, the porosity inside the high-nickel positive electrode material is 1%-5%; for example, it can be specifically 1%, 2%, 3%, 4%, 5%, or a range value composed of any two of the above point values.

[0049] According to some embodiments of the present application, the high-nickel positive electrode material has a hollow structure.

[0050] In the case of having a hollow structure, the active sites for electrochemical reaction between the high-nickel positive electrode material and the electrolyte are increased, which is beneficial to improve the discharge capacity and rate performance. In addition, the hollow structure provides a buffer structure for the anisotropic stress generated in the cycle process, reduces the generation of microcracks of the high-nickel positive electrode material, and the structure is more stable, and the cycle performance is better.

[0051] The test method of the percentage of porosity (including hollow structure) is to take 8 ion-cut cross-section pictures at a rate of 10K or more; for example, high-nickel positive electrode material particles with a second ball cross-section diameter of 5-9 μm after cutting can be selected for measurement, which is approximately the cross-section picture of the approximate middle position of the high-nickel positive electrode material particles. Specifically, MIPAR analysis software is used to automatically identify and calculate the porosity and hollow structure in the cross-section, and the proportion of these blank positions in the total area is read.

[0052] According to some embodiments of the present application, the average particle size (D50) of the high-nickel positive electrode material is 2-16 μm. For example, it can be specifically 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, or a range value formed by any two of the above point values. The average particle size (D50) of the high-nickel positive electrode material is preferably 5-9 μm.

[0053] According to some embodiments of the present application, the high-nickel positive electrode material is a polycrystalline material. That is, a plurality of primary particles are agglomerated to form secondary particles.

[0054] According to some embodiments of the present application, the particle size of the primary particles of the high-nickel positive electrode material is 100-500 nm.

[0055] According to some embodiments of the present application, the particle size of the primary particles of the high-nickel positive electrode material is 200-400 nm. For example, it can be specifically 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, or a range value formed by any two of the above point values.

[0056] According to some embodiments of the second aspect of the present application, a preparation method of the high-nickel positive electrode material provided by the embodiments of the first aspect of the present application is provided, and the preparation method comprises the following steps:

[0057] S1. mixing the precursor, the lithium source and the additive A, and then performing a first firing;

[0058] The first firing comprises a first holding platform and a second holding platform performed in sequence; the temperature of the first holding platform is 350-600 ℃; and the temperature of the second holding platform is 690-800 ℃.

[0059] The precursor contains Ni, Co and M;

[0060] The additive A contains M´;

[0061] S2. mixing the product obtained in step S1 and the additive B, and then performing a second firing;

[0062] The temperature of the second firing is 400-690 ℃.

[0063] The mechanism of the preparation method is as follows:

[0064] In step S1, the first holding platform realizes pre-lithiation, and the second holding platform realizes sufficient sintering, and the temperature controls the crystallinity and particle size of the primary particles; at the same time, in the first firing process, the lithium source and the precursor form a layered lithium metal oxide, and M´ in the additive A is doped in the layered lithium metal oxide, and the two combine to form the matrix material.

[0065] Since the preparation method adopts all the technical solutions of the high-nickel positive electrode material in the above embodiments, at least all the beneficial effects brought by the technical solutions of the above embodiments are possessed.

[0066] Further, in step S1, the particle size of the obtained high-nickel positive electrode material primary particles is small by adjusting the sintering mechanism, thereby improving the rate performance to a certain extent.

[0067] Further, in step S1, M' has occupied the sites of the transition metal layer by doping, so that the additive B in step S2 is more inclined to form interstitials rather than doping; at the same specific sintering temperature, the temperature of the additive B doping the matrix material cannot be reached. Specifically, when the additive B includes a tungsten-containing compound, the tungsten-containing compound generates Li x WO3 and the like compounds fill the pores in the matrix material.

[0068] Therefore, due to the effect of step S1 and the temperature regulation in step S2, the additive B is ensured to stay more in the interstices of the secondary particles rather than being doped in the crystal lattice of the matrix material.

[0069] Further, when M' includes Y or Sr in step S1, M' can improve the surface stability of the high-nickel positive electrode material, avoid defects, and ultimately facilitate the interstitial effect of the additive B in step S2.

[0070] Further, when the additive B includes the zirconium-containing compound and the tungsten-containing compound at the same time, due to the interface chemical bonding and high-temperature diffusion effect, both of them undergo phase change and may react to generate complex products in the sintering. Specifically, when the sintering of step S2 starts, the lithium salt on the surface of the material is converted and decomposed, and ZrO2 remains in the original crystal form without ionization; as the temperature continues to rise, the product Li2O of lithium salt decomposition reacts with the zirconium-containing compound and the tungsten-containing compound, and may generate Li x WO3 or Li x ZrO2 and the like compounds. As the temperature continues to rise, WO3 and ZrO2 further form Zr-O-W bonds, or generate a solid solution of (W, Zr)O2, enter the interstices of the primary particles of the matrix material, and fill the interstices as interstitial agents.

[0071] Further, when the additive B includes the antimony-containing compound or the bismuth-containing compound, the antimony-containing compound or the bismuth-containing compound has a fluxing effect, can promote other components of the additive B to achieve interstitial, and can reduce the sintering temperature to a certain extent to reduce energy consumption.

[0072] Further, through reasonable design of each step, the application creatively realizes the preparation process of high-nickel positive electrode material without water washing, and significantly saves the preparation cost.

[0073] According to some embodiments of the application, in step S1, the precursor is Ni a Co b M c (OH)2, and a+b+c=1.

[0074] According to some embodiments of the application, in step S1, the precursor is Ni a´ Co b´ (OH)2 and a compound containing M, and a´+b´=1. For example, the precursor is Ni a´ Co b´ (OH)2 and a compound containing Mn; or the precursor is Ni a´ Co b´ (OH)2 and a compound containing Al.

[0075] According to some embodiments of the application, in step S1, the precursor is Ni a´´ Co b´´ M c´´ (OH)2 and a compound containing M, and a´´+b´´+c´´=1. For example, the precursor is Ni a´´ Co b´´ Mn c´´ (OH)2 and a compound containing Al, or the precursor is Ni a´´ Co b´´ Mn c´´ (OH)2 and a compound containing Mn, or the precursor is Ni a´´ Co b´´ Al c´´ (OH)2 and a compound containing Mn, or the precursor is Ni a´´ Co b´´ Al c´´ (OH)2 and a compound containing Al.

[0076] At this time, the compound containing M is usually a compound containing aluminum, such as aluminum oxide, aluminum hydroxide or hydroxyl aluminum oxide.

[0077] The proportion of transition metal elements in the precursor and the high-nickel positive electrode material is basically consistent.

[0078] According to some embodiments of the application, Ni a Co b M c (OH)2, Ni a´ Co b´ (OH)2 and Nia´´ Co b´´ M c´´ D50 particle size of (OH)2is independently selected from any value ranging from 2 to 17 pm. For example, it can be independently selected from 6 pm, 13 pm, 8 pm, or about 10 pm. Since the matrix material will inherit the particle size of the precursor, and the subsequent gap filling, coating has little effect on the particle size, the particle size here can also be regarded as the particle size of the high-nickel positive electrode material.

[0079] According to some embodiments of the present application, Ni a Co b M c D50 particle size of (OH)2is independently selected from any value ranging from 2 to 17 pm. For example, it can be independently selected from 6 pm, 13 pm, 8 pm, or about 10 pm. Since the matrix material will inherit the particle size of the precursor, and the subsequent gap filling, coating has little effect on the particle size, the particle size here can also be regarded as the particle size of the high-nickel positive electrode material. a´ Co b´ D50 particle size of (OH)2is independently selected from any value ranging from 2 to 17 pm. For example, it can be independently selected from 6 pm, 13 pm, 8 pm, or about 10 pm. Since the matrix material will inherit the particle size of the precursor, and the subsequent gap filling, coating has little effect on the particle size, the particle size here can also be regarded as the particle size of the high-nickel positive electrode material. a´´ Co b´´ M c´´ D50 particle size of (OH)2is independently selected from any value ranging from 2 to 17 pm. For example, it can be independently selected from 6 pm, 13 pm, 8 pm, or about 10 pm. Since the matrix material will inherit the particle size of the precursor, and the subsequent gap filling, coating has little effect on the particle size, the particle size here can also be regarded as the particle size of the high-nickel positive electrode material.

[0080] In actual production, the type and amount of the additive A are determined according to the chemical formula of the matrix material, which is a routine operation. In other words, the chemical formula of the matrix material can be calculated from the raw materials and their feeding amounts.

[0081] According to some embodiments of the present application, in step S1, the additive A is at least one of oxides, hydroxides, and carbonates of M'. The additive A is preferably an oxide of M'.

[0082] According to some embodiments of the present application, in step S1, the lithium source includes at least one of lithium hydroxide, lithium carbonate, or a hydrate thereof.

[0083] According to some embodiments of the present application, in step S1, the lithium source is lithium hydroxide or lithium hydroxide monohydrate.

[0084] According to some embodiments of the present application, in step S1, the molar ratio of lithium in the lithium source to the metal in the precursor is 1-1.1:1. For example, it can be specifically 1.01:1, 1.02:1, 1.05:1, 1.1:1, or a range value composed of any two of the above point values.

[0085] According to some embodiments of the present application, in step S1, the heating rate to the first holding platform is 1-5°C / min. For example, it can be specifically 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, or a range value composed of any two of the above point values.

[0086] According to some embodiments of the present invention, in step S1, the temperature of the first heat preservation platform is 350~600℃; for example, it can be 350℃, 400℃, 450℃, 500℃, 550℃, 600℃; or a range of values ​​composed of any two of the above points.

[0087] According to some embodiments of the present invention, in step S1, the constant temperature duration of the first heat preservation platform is 2 to 6 hours. For example, it can be 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours; or a range of values ​​composed of any two of the above points.

[0088] According to some embodiments of the present invention, in step S1, the heating rate to the second heat preservation platform is 1~5℃ / min. For example, it can be 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, or a range of values ​​composed of any two of the above points.

[0089] According to some embodiments of the present invention, in step S1, the temperature of the second heat preservation platform is 690~760℃; for example, it can be 690℃, 700℃, 710℃, 720℃, 730℃, 740℃, 750℃, 760℃; or a range of values ​​composed of any two of the above points.

[0090] According to some embodiments of the present invention, in step S1, the constant temperature duration of the second heat preservation platform is 6 to 16 hours. For example, it can be 6 hours, 8 hours, 10 hours, 11 hours, 12 hours, 14 hours, or 16 hours; or a range of values ​​composed of any two of the above points.

[0091] By using a precursor with high porosity, structural shrinkage easily occurs during sintering, especially during the first sintering process, resulting in a hollow structure. Furthermore, the formation of the hollow structure is significantly related to the dopant element M' and the first sintering temperature, both of which directly affect the primary particle crystal growth process of the high-nickel cathode material. By changing the dopant element and the corresponding first sintering temperature, the hollow structure can be controlled.

[0092] According to some embodiments of the present invention, in step S2, the D50 particle size of the zirconium-containing compound in the additive B is 0.5~3 μm, preferably 0.9~2 μm, and more preferably 1~1.2 μm.

[0093] According to some embodiments of the present invention, in step S2, when the additive B includes a tungsten-containing compound, the D50 particle size of the tungsten-containing compound is 1~4 μm, preferably 1.5~3 μm, and more preferably 2~2.5 μm.

[0094] According to some embodiments of the present application, in step S2, the second firing rate is 1-5℃ / min. For example, it can be specifically 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, or a range value composed of any two of the above point values.

[0095] According to some embodiments of the present application, in step S2, the second firing temperature is 500-650℃. For example, it can be specifically 500℃, 550℃, 600℃, 650℃, or a range value composed of any two of the above point values.

[0096] According to some embodiments of the present application, in step S2, the second firing time is 5-12h. For example, it can be specifically 6h, 8h, 10h, 12h, or a range value composed of any two of the above point values.

[0097] In actual production, the amount of additive B is determined according to the design concentration of the target element in the high-nickel positive electrode material, or the porosity of the base material, or the required porosity of the high-nickel positive electrode material, etc.

[0098] According to some embodiments of the present application, the preparation method further comprises the following step after step S2:

[0099] S3. Mixing the product obtained in step S2 and additive C and then performing a third firing.

[0100] According to some embodiments of the present application, in step S3, the mass percentage of additive C in the product obtained in step S2 is greater than 0 and ≤4%. For example, it can be specifically 0.2%, 0.3%, 0.4%, 0.5%, 1%, 2%, 3%, 4%, or a range value composed of any two of the above point values.

[0101] In actual production, the loss on ignition of additive C is very small, and the total mass of additive C is also very small; therefore, the amount of additive C can also be determined according to the required mass percentage of the coating layer in the high-nickel positive electrode material.

[0102] According to some embodiments of the present application, in step S3, the third firing rate is 1-5℃ / min. For example, it can be specifically 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, or a range value composed of any two of the above point values.

[0103] According to some embodiments of the present application, in step S3, the third firing temperature is 300-600℃. For example, it can be specifically 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, 600℃, or a range value composed of any two of the above point values.

[0104] According to some embodiments of the present application, the duration of the third firing in step S3 is 5-12 hours. For example, it can be specifically 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, or a range value formed by any two of the above point values.

[0105] In the preparation method, the first firing, the second firing and the third firing are all carried out in an oxygen-containing atmosphere. In the oxygen-containing atmosphere, the oxygen concentration is ≥ 90%. For example, it can be specifically 92%, 95%, or a range value formed by any two of the above point values.

[0106] According to the embodiments of the second aspect of the present application, a lithium ion battery is provided, which comprises the high-nickel positive electrode material according to the embodiments of the first aspect of the present application, or comprises the high-nickel positive electrode material prepared by the preparation method according to the embodiments of the second aspect of the present application.

[0107] Since the lithium ion battery adopts the high-nickel positive electrode material or the preparation method according to the embodiments described above, it at least has all the beneficial effects brought by the technical solutions of the embodiments described above.

[0108] According to some embodiments of the present application, the lithium ion battery comprises at least one of a button cell, a soft-packaged cell, a prismatic cell and a cylindrical cell.

[0109] According to some embodiments of the present application, the lithium ion battery comprises at least one of a symmetric cell, a half cell and a full cell.

[0110] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent from the description, or can be learned by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0111] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the accompanying drawings, in which:

[0112] Fig. 1 is a cross-sectional SEM image of the high-nickel positive electrode material obtained in Example 1 of the present application.

[0113] Fig. 2 is a cross-sectional SEM image of the high-nickel positive electrode material obtained in Example 8 of the present application.

[0114] Fig. 3 is a cross-sectional SEM image of the high-nickel positive electrode material obtained in Comparative Example 1 of the present application.

[0115] Fig. 4 is a cycle result graph of the high-nickel positive electrode material obtained in Example 1 and Comparative Example 1 of the present application.

[0116] Fig. 5is a rate performance diagram of the high-nickel positive electrode material obtained in Example 1 and Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0117] The concept and technical effects of the present application will be described in detail below in combination with examples, so as to fully understand the purposes, features and effects of the present application. Obviously, the described examples are only some of the examples of the present application, but not all the examples. Based on the examples of the present application, other examples obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0118] In the description of the present application, the description of the terms “one embodiment”, “some embodiments”, “illustrative embodiment”, “example”, “specific example” or “some examples” means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are contained in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0119] Example 1

[0120] In this example, a high-nickel positive electrode material is prepared, and the specific steps are as follows:

[0121] S1. In an atmosphere with an oxygen concentration of 92%, a precursor, a lithium source and an additive A are mixed according to the chemical formula LiNi 0.888 Co 0.100 M 0.010 M´ 0.002 O2; the precursor, the lithium source and the additive A are mixed and then subjected to a first firing to form a base material;

[0122] wherein M´ = Sr 0.001 Y 0.001 , M is Al, and M´ is contained in the additive A;

[0123] The precursor is a mixture of Ni 0.90 Co 0.10 (OH)2 and Al2O3, the D50 particle size of Ni 0.90 Co 0.10 (OH)2 is about 8.0 μm; the porosity is 6.8%, and it is purchased from Jincheng Energy Company; the additive A is a mixture of strontium oxide and yttrium oxide; the lithium source is lithium hydroxide monohydrate, and the molar ratio of lithium element in the lithium salt to the precursor is 1.015:1;

[0124] One burning includes first holding platform and second holding platform in turn; specifically, first heating to first holding platform temperature 520℃ at 3℃ / min, holding for 4h; then heating to second holding platform temperature 730℃ at 2℃ / min, holding for 11h.

[0125] S2. After mixing the product obtained in step S1 and additive B, two burning is carried out in an atmosphere with an oxygen concentration of 92%, and after cooling, the product is sieved through a 325 mesh screen to obtain a matrix material and a gap filling material filled in the pores of the matrix material.

[0126] The additive B is a mixture of zirconium oxide and tungstic acid, and the addition amount is calculated according to the addition concentration shown in Table 1. The particle size D50 of the zirconium oxide is 1.07 μm, and the particle size D50 of the tungstic acid is 2.29 μm.

[0127] The second burning includes holding at 600℃ for 8h after heating at 3℃ / min.

[0128] S3. After mixing the product obtained in step S2 and additive C, three burning is carried out in an atmosphere with an oxygen concentration of 92%, and after three burning, the product is cooled and sieved through a 325 mesh screen to obtain a high-nickel positive electrode material with a coating layer; the particle size is 7.1 μm, and the porosity is 2.3%. The temperature of the three burning is 450℃, the time is 7h, and the heating rate is 3℃ / min; the additive C is a mixture of aluminum oxide and titanium oxide in a mass ratio of 1:1, and the addition amount is 0.3% relative to the mass of the product obtained in step S2.

[0129] Examples 2-8 each prepared a high-nickel positive electrode material, and the specific differences from Example 1 are shown in Table 1. The precursor used in Example 8 has a porosity of 8.9%, and is purchased from Jinchi Energy Company.

[0130] Table 1. Part of the parameters of Examples 1-8

[0131]

[0132] Comparative Example 1

[0133] This example prepared a high-nickel positive electrode material, and the specific difference from Example 1 is that:

[0134] In step S2, no additive B is added. As shown in Table 1, the cross-sectional porosity of the high-nickel positive electrode material particles is 3.2%. Fig. 3

[0135] Comparative Example 2

[0136] This example prepared a high-nickel positive electrode material, and the specific difference from Example 1 is that:

[0137] ​In step S2, the additive B is tungstic acid, and the additive amount of the tungstic acid is the same as that of the tungstic acid in Example 1.

[0138] Comparative Example 3

[0139] In this example, a high-nickel positive electrode material is prepared, and the difference from Example 1 is that:

[0140] In step S2, the additive B is zirconium oxide, and the additive amount of the zirconium oxide is the same as that of the zirconium oxide in Example 1.

[0141] Comparative Example 4

[0142] In this example, a high-nickel positive electrode material is prepared, and the difference from Example 1 is that:

[0143] In step S1, the first holding platform is not set, that is, the temperature is directly raised from room temperature to the constant temperature of the second holding platform, which is 730℃, and the temperature is maintained for 11h.

[0144] Comparative Example 5

[0145] In this example, a high-nickel positive electrode material is prepared, and the difference from Example 1 is that:

[0146] In step S1, no additive A is added.

[0147] Comparative Example 6

[0148] In this example, a high-nickel positive electrode material is prepared, and the difference from Example 1 is that:

[0149] In step S2, the temperature of the second firing is 750℃.

[0150] Comparative Example 7

[0151] In this example, a high-nickel positive electrode material is prepared, and the difference from Example 1 is that:

[0152] In step S2, the temperature of the second firing is 350℃.

[0153] Application Example

[0154] In this example, a lithium ion battery is prepared, and specifically:

[0155] The high-nickel positive electrode material prepared in the example or comparative example, the conductive agent SuperP, and the binder polyvinylidene fluoride (PVDF) are mixed and stirred uniformly at a mass ratio of 90:5:5 and N-methyl pyrrolidone (NMP) to prepare a positive electrode slurry (solid content about 40%), which is coated on a current collector aluminum foil, dried at 105℃, and then rolled at room temperature to a surface density of 2.8g / cm 3 to 3.3g / cm 3Then punching, cutting into φ14mm round sheet, made into positive plate.

[0156] The coin cell was assembled in the glove box. The coin cell was assembled in the order of "negative shell-foam nickel-lithium sheet (φ18mm)-8 drops of electrolyte-separator (φ22mm, 16μm thick)-8 drops of electrolyte-positive plate-positive shell", wherein the electrolyte was composed of ethylene carbonate (EC), methyl ethyl carbonate (EMC) and dimethyl carbonate (DMC) (EC: EMC: DMC volume ratio = 1:1:1) containing 1.0M LiPF6; the size of the battery shell (positive shell and negative shell) was 24mm. The assembled coin cell was placed in the mold groove of a hydraulic sealing machine (purchased from Shenzhen Kejing Zhida Technology Co., Ltd.), locked, and the pressure was >450kg / cm 2 Then unlocked, and the sealed coin cell was taken out as the lithium ion battery obtained in this example.

[0157] Test Example 1

[0158] In this example, the morphology of the high-nickel positive electrode material obtained in the examples and the comparative examples was tested, and the specific test results are shown in Table 1. Figs. 1-3 The general SEM test results show that the high-nickel positive electrode materials obtained in Example 1 and Comparative Example 1 are both secondary spherical, and the porosity of Example 1 is lower than that of Comparative Example 1 due to the addition of the interstitial material. In Example 8, the amount of the dopant is adjusted, the one-shot mechanism is adjusted, and a precursor with higher porosity is used, so that a hollow structure is generated in the high-nickel positive electrode material obtained in Example 8. Further, the particle size distribution of the primary particles of the high-nickel positive electrode material obtained in the examples is between 200-400nm.

[0159] Test Example 2

[0160] In this example, the rate performance and cycle performance of the lithium ion battery obtained in the application examples were tested.

[0161] The test method of the cycle performance is as follows: at 25℃, the charge-discharge cycle characteristics of the coin cell were detected by using a blue electric test cabinet, and 1C=195mA / g was set. The charge-discharge was carried out in the voltage range of 3.0V to 4.3V at 1C charge and 2C discharge, specifically, 1C constant current charging to 4.3V, then constant voltage charging to 0.02C cutoff current at 4.3V, standing for 5min, discharging to 3.0V at 2C, standing for 5min, and recording the charge-discharge capacity after the first cycle. As above, the cycle was carried out in turn, and after 50 cycles of charge / discharge, the charge-discharge capacity after the 50th cycle was recorded. Cycle capacity retention rate (%) = (50th cycle discharge capacity / 1st cycle discharge capacity) x 100%.

[0162] The test method of rate performance is as follows: at 25℃, the blue test cabinet button type battery test. Set 1C = 195mA / g, charge / discharge at 0.1C, in the voltage interval of 3.0V to 4.3V, specifically, charge at 0.1C to 4.3V, then charge at 4.3V voltage to the cutoff current 0.02C, stand for 5min, discharge at 0.1C to 3.0V, stand for 5min, record the charge and discharge capacity. Then continuously perform this test at 0.2C, 0.5C, 1C, 2C, record the charge and discharge capacity, and calculate the proportion of reversible capacity at 1C / 0.1C rate.

[0163] The test results of the above electrochemical performance are shown in Table 2 and Figs. 4-5

[0164] Table 2 Electrochemical performance results of high-nickel positive electrode materials obtained by examples and comparative examples

[0165]

[0166] The results in Table 2 show that within the range provided by the present application, changing parameters can obtain excellent effects of 50-week cycle retention rate ≥ 94% and 1C / 0.1C rate performance ≥ 90%. Due to the above excellent effects, the high-nickel positive electrode material provided by the present application, or the lithium ion battery comprising the above high-nickel positive electrode material, is expected to be widely used in the field of energy storage technology, the field of power battery or the field of communication electronics.

[0167] From the results of Comparative Example 1 and Comparative Examples 1-3, if additive B is not added, or the type of additive B is not within the range claimed in the present application, the overall performance of the obtained high-nickel positive electrode material will significantly decrease. Therefore, it can be known that the interstitial substance in the present application can indeed improve the cycle performance and rate performance to a certain extent, and there is a significant synergistic effect between the various additives B.

[0168] From Comparative Example 1 and Comparative Examples 4-7, if the one-shot mechanism and the two-shot mechanism are not within the range claimed in the present application, or additive A is not added, the overall performance of the obtained high-nickel positive electrode material will significantly decrease. Therefore, it can be known that in the preparation method in the present application, there is a significant synergistic effect between the conditions and the doping substances and the interstitial substances.

[0169] The embodiments of the present application are described in detail above in combination with the drawings, but the present application is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by a person skilled in the art without departing from the purpose of the present application. In addition, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.​

Claims

1. A high-nickel positive electrode material, characterized by, The high-nickel positive electrode material comprises: a base material having a chemical formula of LiNi x Co y M z M´ w O2, wherein 0.80≤x≤0.98, 0.02≤y≤0.20, 0≤z≤0.06, 0<w≤0.02; x+y+z+w=1; M is at least one of Mn and Al, M´ is at least one of Y, Sr, La, B, Mg and Ti; the base material has pores; a filler material, the filler material being present inside the pores, the filler material comprising a sintered product derived from an additive B, the additive B is one of the following combinations: a combination of a zirconium-containing compound and a tungsten-containing compound; a combination of a zirconium-containing compound, a tungsten-containing compound and an antimony-containing compound; a combination of a zirconium-containing compound, a tungsten-containing compound and a bismuth-containing compound. 2.The high-nickel cathode material of claim 1, wherein, The high-nickel positive electrode material further has a coating layer, the coating layer comprises a sintered product derived from an additive C, the additive C comprises an aluminum-containing compound and a titanium-containing compound. 3.The high-nickel cathode material of claim 1, wherein, The porosity inside the high-nickel positive electrode material is 0.2% to 6%; and / or, the average particle size of the high-nickel positive electrode material is 2 to 16 μm.

4. The high-nickel positive electrode material according to any one of claims 1 to 3, characterized by, The high-nickel positive electrode material has a hollow structure.

5. The high-nickel cathode material of any one of claims 1-3, wherein, The concentration of the target element introduced by a single additive B in the high-nickel positive electrode material is 0 to 5000 ppm; the concentration of the target element introduced by all additive B in the high-nickel positive electrode material is > 0 ppm; The target element is Zr, W, Sb and Bi.

6. A method for preparing the high-nickel positive electrode material according to any one of claims 1 to 5, characterized by, The preparation method comprises the following steps: S1. mixing a precursor, a lithium source and an additive A, and then performing a first firing; The first firing comprises a first holding platform and a second holding platform performed in sequence; the temperature of the first holding platform is 350 to 600°C; the temperature of the second holding platform is 690 to 800°C; The precursor contains Ni, Co and M; The additive A contains M´; S2. mixing the product obtained in step S1 and the additive B, and then performing a second firing; The temperature of the second firing is 400 to 690°C.

7. The production method according to claim 6, wherein In step S1, the precursor is one of the following combinations: (1) Ni a Co b M c (OH)2, and a+b+c = 1; (2) Ni a´ Co b´ (OH)2and the M-containing compound, and a' + b' = 1; (3) Ni a´´ Co b´´ M c´´ (OH)2and the M-containing compound, and a" + b" + c" = 1.

8. The preparation method according to claim 6, characterized in that, The preparation method further comprises the following step after step S2: S3. mixing the product obtained in step S2 and an additive C, and then performing a third firing.

9. The method of any one of claims 6 to 8, wherein the method further comprises the step of: The preparation method satisfies at least one of the following conditions: (a) the constant temperature time length of the first holding platform is 2 to 6 h; (b) the constant temperature time length of the second holding platform is 6 to 16 h; (c) the time length of the second firing is 5 to 12 h.

10. A lithium-ion battery, characterized by, The lithium ion battery comprises the high-nickel positive electrode material according to any one of claims 1 to 5, or the high-nickel positive electrode material prepared by the preparation method according to any one of claims 6 to 9.

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