High-nickel positive electrode material as well as preparation method and application thereof

Abstract

The invention discloses a high-nickel positive electrode material and a preparation method and application thereof, and belongs to the technical field of new energy. The high-nickel positive electrode material provided by the invention comprises a porous matrix material and a gap filling substance, the chemical general formula of the matrix material is LiNixCoyMzMwO2, x is more than or equal to 0.80 and less than or equal to 0.98, y is more than or equal to 0.02 and less than or equal to 0.20, z is more than or equal to 0 and less than or equal to 0.06, and w is more than 0 and less than or equal to 0.02; x + y + z + w = 1; m is at least one of Mn and Al, and M is at least one of Y, Sr, La, B, Mg and Ti; the interstitial substance is present inside the pores and includes a sinter derived from an additive B including 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 provided by the invention has excellent long cycle performance and rate capability. The invention also provides a preparation method and application of the high-nickel positive electrode material.

Description

Technical Field

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

[0002] With the expansion and development of fields such as power tools and drones, the performance requirements of related equipment for lithium batteries are getting higher and higher, and lithium-ion batteries require higher capacity and greater rate. Correspondingly, the positive electrode material is required to have higher capacity and better rate performance. Increasing the Ni content is one of the effective methods to increase 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 the transition metal, it is called a high-nickel material. On the basis of already having a higher capacity, it is particularly important to improve the cycle performance and rate performance of the high-nickel material.

[0003] Industry is attempting to improve the stability of high-nickel cathode materials and enhance their long-cycle performance through methods such as doping and coating modification, sintering, and post-processing optimization. However, traditional modification methods have achieved limited results, and the cycling stability and high-rate performance of high-nickel cathode materials still need to be further improved. Summary of the Invention

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

[0005] The present invention also provides a method for preparing the high-nickel positive electrode material.

[0006] The present invention 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 invention, a high-nickel positive electrode material is provided, wherein the high-nickel positive electrode material comprises: Matrix material, the chemical formula of the matrix material is 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, and M' is at least one of Y, Sr, La, B, Mg and Ti; and the matrix material has pores; a filling substance present inside the pores, the filling substance comprising a sintered substance derived from the additive B, 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.

[0008] The high-nickel positive electrode material according to the embodiment of the present invention has at least the following beneficial effects: Filling the pores of the base material with the filling material is beneficial to improving the mechanical properties of the high-nickel positive electrode material and enhancing the stability.

[0009] The selection and combination of the additives B can either synergistically improve the density of the filling, or synergistically improve the uniformity of the filling, or promote each other's penetration into the pores; overall, the comprehensive performance of the obtained high-nickel positive electrode material is improved.

[0010] In M's choice, Y's 3+ -O 2 -Ni 4+ Electron cloud coupling mechanism, suppressing oxygen vacancy generation and reducing the high-activity Ni 4+ concentration, thereby improving the structural stability and electrochemical performance of the high-nickel positive electrode material. Specifically, the rate, cycle, and high-temperature performance are significantly improved. Sr doping can effectively improve the structural stability of the high-nickel ternary positive electrode material. At the same time, the matrix material with a surface rich in Sr can effectively block the side reactions between the electrolyte and the interior of the high-nickel positive electrode material, enhance the stability of the crystal structure of its primary particle surface, and prevent the degradation of the crystal structure of the high-nickel positive electrode material from the outside to the inside. Mg, Ti, etc. can replace transition metals (Ni, Co, Mn) or Li positions, inhibit phase changes, reduce cation mixing, and enhance structural stability. B doping can partially replace O positions, enhance lattice stability, reduce oxygen release, and inhibit electrolyte decomposition. Doping with the rare earth element La can effectively improve the thermal stability and cycle life of the material.

[0011] In summary, the high-nickel cathode material provided by the present invention can effectively improve its structural stability and reduce the occurrence of surface side reactions through specific types of doping (M') and specific types of filling, thereby improving its cycling performance. At the same time, due to the selection of doping and filling materials, the lithium ion conductivity of the obtained high-nickel cathode material is significantly improved, thereby improving its rate performance.

[0012] According to some embodiments of the present invention, the matrix material LiNi x Co y M z M´ w In O2, 0.80≤x≤0.98. For example, x can be 0.80, 0.82, 0.85, 0.88, 0.90, 0.92, 0.95, 0.98, or a range consisting of any two of the above values.

[0013] According to some embodiments of the present invention, the matrix material LiNi x Coy M z M´ w In O2, 0.02≤y≤0.15. For example, it can be 0.02, 0.04, 0.06, 0.08, 0.09, 0.10, 0.12, 0.15, or a range consisting of any two of the above points.

[0014] According to some embodiments of the present invention, the matrix material LiNi x Co y M z M´ w In O2, 0.01≤z≤0.03. For example, it can be 0.01, 0.02, 0.03, or a range consisting of any two of the above values.

[0015] According to some embodiments of the present invention, the matrix material LiNi x Co y M z M´ w In O2, 0<w≤0.02, preferably 0<w≤0.015, more preferably 0.001≤w≤0.01. For example, it can be 0.002, 0.003, 0.004, 0.005, 0.008, 0.010, 0.015, or a range consisting of any two of the above values.

[0016] When the doping amount of the doping element M' is small, it is insufficient to stabilize the lattice and inhibit side reactions; 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 lithium ion deintercalation path.

[0017] According to some embodiments of the present invention, the matrix material LiNi x Co y M z M´ w In O2, M is Al.

[0018] According to some embodiments of the present invention, the matrix material LiNi x Co y M z M´ w In O2, M' is at least one of Y and Sr. More specifically, M' is a combination of Y and Sr; wherein the molar ratio of Y to Sr is any molar ratio, for example, specifically 0.1-0.9:0.1-0.9; more specifically, 0.8-1.2:1.

[0019] According to some embodiments of the present invention, the concentration of the target element introduced by a 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 greater than 0 ppm; The target elements are Zr, W, Sb and Bi.

[0020] According to some embodiments of the present invention, when the additive B includes a zirconium-containing compound, the concentration of the Zr element derived from the additive B in the high-nickel positive electrode material is 0-5000 ppm.

[0021] According to some embodiments of the present invention, when the additive B includes a zirconium-containing compound, the concentration of the Zr element derived from the additive B in the high-nickel positive electrode material is 500-4000 ppm. For example, the concentration may be 500 ppm, 600 ppm, 800 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, 3500 ppm, 4000 ppm, or a range consisting of any two of the above values.

[0022] According to some embodiments of the present invention, when the additive B includes a tungsten-containing compound, the concentration of the W element derived from the additive B in the high-nickel positive electrode material is 0-5000 ppm.

[0023] According to some embodiments of the present invention, when the additive B includes a tungsten-containing compound, the concentration of the W element derived from the additive B in the high-nickel positive electrode material is 500-5000 ppm. For example, the concentration may be 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 consisting of any two of the above values.

[0024] According to some embodiments of the present invention, when the additive B includes a bismuth-containing compound, the concentration of the Bi element derived from the additive B in the high-nickel positive electrode material is 0-5000 ppm.

[0025] According to some embodiments of the present invention, when the additive B includes a bismuth-containing compound, the concentration of the Bi element derived from the additive B in the high-nickel positive electrode material is 500-3000 ppm. For example, the concentration may be 500 ppm, 600 ppm, 800 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, or a range consisting of any two of the above values.

[0026] According to some embodiments of the present invention, when the additive B includes an antimony-containing compound, the concentration of the Sb element derived from the additive B in the high-nickel positive electrode material is 0-5000 ppm.

[0027] According to some embodiments of the present invention, when the additive B includes an antimony-containing compound, the concentration of the Sb element derived from the additive B in the high-nickel positive electrode material is 500-3000 ppm. For example, the concentration may be 500 ppm, 600 ppm, 800 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, or a range consisting of any two of the foregoing values.

[0028] According to some embodiments of the present invention, the matrix material is a secondary spherical material composed of an arrangement of primary particles. Because the interstitial filler and subsequent coating material do not significantly affect the overall morphology of the high-nickel cathode material, the high-nickel cathode material can also be considered a secondary spherical material (also known as a polycrystalline material).

[0029] According to some embodiments of the present invention, the additive B is a combination of a zirconium-containing compound and a tungsten-containing compound.

[0030] According to some embodiments of the present invention, the additive B is a combination of a zirconium-containing compound, a tungsten-containing compound, and an antimony-containing compound.

[0031] According to some embodiments of the present invention, the additive B is a combination of a zirconium-containing compound, a tungsten-containing compound, and a bismuth-containing compound.

[0032] According to some embodiments of the present invention, the zirconium-containing compound comprises at least one of zirconium oxide, zirconium hydroxide, zirconium fluoride, zirconium carbonate, zirconium chloride, and zirconium nitrate.

[0033] According to some embodiments of the present invention, the tungsten-containing compound includes at least one of tungstic acid, tungsten oxide (tungsten trioxide), tungsten hydroxide, tungsten hexafluoride, tungsten chloride, sodium tungstate, and potassium tungstate.

[0034] According to some embodiments of the present invention, the antimony-containing compound comprises at least one of antimony trioxide, antimony pentoxide, antimony trichloride and sodium antimonate.

[0035] According to some embodiments of the present invention, the bismuth-containing compound comprises at least one of bismuth oxide, bismuth sulfate, and bismuth chloride.

[0036] According to some embodiments of the present invention, the high-nickel positive electrode material further comprises a coating layer, wherein the coating layer comprises a sintered product derived from an additive C, wherein the additive C comprises an aluminum-containing compound and a titanium-containing compound.

[0037] According to some embodiments of the present invention, the coating layer is wrapped around the surface of the high-nickel positive electrode material.

[0038] According to some embodiments of the present invention, the aluminum-containing compound comprises at least one of aluminum oxide, aluminum hydroxide, and aluminum fluoride.

[0039] According to some embodiments of the present invention, the titanium-containing compound comprises at least one of titanium oxide and titanium chloride.

[0040] According to some embodiments of the present invention, in the additive C, the mass ratio of the aluminum-containing compound to the titanium-containing compound is 1:0.5~4; for example, it can be 1:0.8, 1:1, 1:2, 1:3, 1:4, or a range value consisting of any two of the above point values.

[0041] According to some embodiments of the present invention, the mass percentage of the coating layer to the high-nickel positive electrode material is greater than 0 and ≤ 4%, for example, 0.2%, 0.3%, 0.4%, 0.5%, 1%, 2%, 3%, 4%, or a range consisting of any two of the above values.

[0042] According to some embodiments of the present invention, the porosity inside the high-nickel positive electrode material is 0.2% to 6%.

[0043] According to some embodiments of the present invention, the porosity of the high-nickel positive electrode material is 1% to 5%, for example, 1%, 2%, 3%, 4%, 5%, or a range consisting of any two of the above values.

[0044] According to some embodiments of the present invention, the high-nickel positive electrode material has a hollow structure.

[0045] In the case of a hollow structure, the active sites for electrochemical reactions between the high-nickel cathode material and the electrolyte increase, which is conducive to improving its discharge capacity and rate performance. In addition, the hollow structure provides a buffer for the anisotropic stress generated during the cycle, reducing the generation of microcracks in the high-nickel cathode material, making the structure more stable and improving the cycle performance.

[0046] The testing method for the percentage of the porosity (including hollow structure) is to take 8 ion cutting cross-sectional images at a magnification of 10K or above. For example, a high-nickel positive electrode material particle with a secondary spherical cross-sectional diameter of 5~9μm after cutting can be selected for measurement. At this time, the cross-sectional image is approximately close to the center position of the high-nickel positive electrode material particle. Specifically, the MIPAR analysis software is used to automatically identify and measure the pores and hollow structures in the cross-section, and read the proportion of these blank positions to the total area.

[0047] According to some embodiments of the present invention, the average particle size (D50) of the high-nickel cathode material is 2-16 μm. Specifically, for example, it can be 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 consisting of any two of the aforementioned values. The average particle size (D50) of the high-nickel cathode material is preferably 5-9 μm.

[0048] According to some embodiments of the present invention, the high-nickel cathode material is a polycrystalline material, that is, a secondary particle formed by agglomeration of multiple primary particles.

[0049] According to some embodiments of the present invention, the primary particles of the high-nickel positive electrode material have a particle size of 100-500 nm.

[0050] According to some embodiments of the present invention, the primary particles of the high-nickel cathode material have a particle size of 200-400 nm, for example, 200, 250, 300, 350, 400 nm, or a range consisting of any two of the above values.

[0051] According to an embodiment of the second aspect of the present invention, a method for preparing the high-nickel positive electrode material provided in an embodiment of the first aspect of the present invention is provided, the preparation method comprising the following steps: S1. The precursor, lithium source and additive A are mixed and then burned; The first calcination includes a first heat preservation platform and a second heat preservation platform in sequence; the temperature of the first heat preservation platform is 350-600°C; the temperature of the second heat preservation platform is 690-800°C; The precursor contains Ni, Co and M; The additive A contains M´; S2. The product obtained in step S1 and the additive B are mixed and then burned; The temperature of the secondary firing is 400-690°C.

[0052] The mechanism of the preparation method is as follows: In step S1, the first insulation platform achieves pre-lithiation, the second insulation platform achieves full sintering, and the degree of crystallization and particle size of the primary particles are controlled by temperature; at the same time, during the primary sintering process, the lithium source and the precursor form a layered lithium metal oxide, and the M' in the additive A is doped in the above-mentioned layered lithium metal oxide, and the two are combined to form the matrix material.

[0053] Since the preparation method adopts all the technical solutions of the high-nickel positive electrode material of the above embodiment, it at least has all the beneficial effects brought by the technical solutions of the above embodiment.

[0054] Furthermore, in step S1, through the adjustment of the sintering mechanism, the particle size of the primary particles of the obtained high-nickel positive electrode material is smaller, thereby improving its rate performance to a certain extent.

[0055] Furthermore, since M' has already occupied the sites of the transition metal layer in step S1, the additive B in step S2 is more inclined to form gap filling rather than doping. At the same time, at a specific calcination temperature, the temperature at which the additive B can dope the matrix material cannot be reached. Specifically, when the additive B includes a tungsten-containing compound, the tungsten-containing compound generates Li as the calcination proceeds under the action of other substances such as lithium salts and other additives B. x Compounds such as WO3 fill the pores of the matrix material.

[0056] Therefore, due to the effect of step S1 and the temperature control in step S2, it is ensured that the additive B stays more in the gaps of the secondary particles rather than being doped in the lattice of the matrix material.

[0057] Furthermore, when M' includes Y or Sr in step S1, M' can enhance the surface stability of the high-nickel positive electrode material, avoid defects, and ultimately facilitate the interstitial filling effect of the additive B in step S2.

[0058] Furthermore, when the additive B includes both the zirconium-containing compound and the tungsten-containing compound, due to the interfacial chemical bonding and high-temperature diffusion, the two undergo phase transition during calcination and may react to form complex products. Specifically, when the calcination of step S2 begins, the lithium salt on the surface of the material is converted and decomposed, while ZrO2 maintains its original crystal form and does not ionize; as the temperature continues to rise, the decomposition product of the lithium salt, Li2O, reacts with the zirconium-containing compound and the tungsten-containing compound, possibly generating Li x WO or Li x As the temperature is further increased or the temperature is further increased, WO3 and ZrO2 further form Zr-OW bonds, or generate a solid solution of (W, Zr)O2, which enters the primary particle gaps of the matrix material and fills the gaps as a filler.

[0059] Furthermore, when the additive B includes the antimony-containing compound or the bismuth-containing compound, the antimony-containing compound or the bismuth-containing compound also has a fluxing effect, which can promote the filling of other components of the additive B, and can reduce the second firing temperature to a certain extent, thereby reducing energy consumption.

[0060] Furthermore, through the rational design of each step, the present invention creatively realizes the preparation process of high-nickel positive electrode materials without water washing, which significantly saves the preparation cost.

[0061] According to some embodiments of the present invention, in step S1, the precursor is Ni a Co b M c (OH)2, and a+b+c=1.

[0062] According to some embodiments of the present invention, 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 Mn-containing compound; or the precursor is Ni a´ Co b´ (OH)2 and Al-containing compounds.

[0063] According to some embodiments of the present invention, 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 Al-containing compound, or the precursor is Ni a´´ Co b´´ Mn c´´ (OH)2 and a Mn-containing compound, or the precursor is Ni a´´ Co b´´ Al c´´ (OH)2 and a Mn-containing compound, or the precursor is Ni a´´ Co b´´ Al c´´ (OH)2 and Al-containing compounds.

[0064] In this case, the M-containing compound is generally an aluminum-containing compound, such as aluminum oxide, aluminum hydroxide, or aluminum oxyhydroxide.

[0065] The ratio of transition metal elements in the precursor and the high-nickel positive electrode material is substantially consistent.

[0066] According to some embodiments of the present invention, Ni a Co b M c (OH)2、Ni a´ Co b´ (OH)2 and Ni a´´ Co b´´ M c´´The D50 particle size of (OH)2 is independently selected from any value between 2 and 17 μm. For example, it can be independently selected from 6 μm, 13 μm, 8 μm, or about 10 μm. Since the matrix material inherits the particle size of the precursor, and the subsequent filling and coating have 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.

[0067] According to some embodiments of the present invention, Ni a Co b M c (OH)2、Ni a´ Co b´ (OH)2 and Ni a´´ Co b´´ M c´´ The porosity of (OH)2 is independently selected from any value between 1% and 16%. For example, it can be independently selected from 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 10%, 12%, 14%, 16%, or a range consisting of any two of the above values.

[0068] In actual production, it is a routine operation to determine the type and amount of the additive A based on the chemical formula of the base material. In other words, the chemical formula of the base material can usually be calculated from the raw materials and their addition amounts.

[0069] According to some embodiments of the present invention, in step S1, the additive A is at least one of an oxide, a hydroxide, and a carbonate of M'. The additive A is preferably an oxide of M'.

[0070] According to some embodiments of the present invention, in step S1, the lithium source includes at least one of lithium hydroxide, lithium carbonate, or hydrates thereof.

[0071] According to some embodiments of the present invention, in step S1, the lithium source is lithium hydroxide or lithium hydroxide monohydrate.

[0072] According to some embodiments of the present invention, 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 1.01:1, 1.02:1, 1.05:1, 1.1:1; or a range value consisting of any two of the above point values.

[0073] According to some embodiments of the present invention, in step S1, the heating rate to the first insulation platform is 1-5°C / min. For example, it can be 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, or a range consisting of any two of the above values.

[0074] According to some embodiments of the present invention, in step S1, the temperature of the first insulation platform is 350~600℃; for example, it can be 350℃, 400℃, 450℃, 500℃, 550℃, 600℃; or a range value consisting of any two of the above point values.

[0075] 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, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, or a range consisting of any two of the above values.

[0076] According to some embodiments of the present invention, in step S1, the heating rate to the second insulation platform is 1-5°C / min. For example, it can be 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, or a range consisting of any two of the above values.

[0077] According to some embodiments of the present invention, in step S1, the temperature of the second insulation platform is 690~760℃; for example, it can be 690℃, 700℃, 710℃, 720℃, 730℃, 740℃, 750℃, 760℃; or a range value consisting of any two of the above point values.

[0078] 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, 6 hours, 8 hours, 10 hours, 11 hours, 12 hours, 14 hours, 16 hours, or a range consisting of any two of the above values.

[0079] Using a precursor with a relatively high porosity increases the likelihood of structural shrinkage during sintering, particularly during the first firing process, resulting in a hollow structure. Furthermore, the formation of the hollow structure is significantly correlated with the doping element M' and the first firing temperature, both of which directly influence the primary particle crystal growth process of the high-nickel cathode material. By varying the doping element and the corresponding first firing temperature, the hollow structure can be manipulated.

[0080] According to some embodiments of the present invention, in step S2, in the additive B, the zirconium-containing compound has a D50 particle size of 0.5-3 μm, preferably 0.9-2 μm, and more preferably 1-1.2 μm.

[0081] 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.

[0082] According to some embodiments of the present invention, in step S2, the heating rate of the second calcination is 1-5°C / min. For example, it can be 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, or a range consisting of any two of the above values.

[0083] According to some embodiments of the present invention, in step S2, the secondary calcination temperature is 500-650° C. For example, it can be 500° C., 550° C., 600° C., 650° C., or a range consisting of any two of the above values.

[0084] According to some embodiments of the present invention, in step S2, the duration of the second burning is 5 to 12 hours, for example, 6 hours, 8 hours, 10 hours, 12 hours, or a range consisting of any two of the above values.

[0085] In actual production, the amount of additive B added is determined based on factors such as the designed concentration of the target element in additive B in the high-nickel positive electrode material, the porosity of the matrix material, or the porosity required by the high-nickel positive electrode material.

[0086] According to some embodiments of the present invention, the preparation method further comprises the following steps after step S2: S3. The product obtained in step S2 and additive C are mixed and then calcined.

[0087] According to some embodiments of the present invention, in step S3, the mass percentage of the additive C in the product obtained in step S2 is greater than 0 and ≤ 4%. For example, it can be 0.2%, 0.3%, 0.4%, 0.5%, 1%, 2%, 3%, 4%, or a range consisting of any two of the above values.

[0088] In actual production, the ignition loss of the additive C is very small, and the total mass of the additive C is also very small; therefore, the amount of the additive C added can also be determined according to the mass percentage of the required coating layer to the high-nickel positive electrode material.

[0089] According to some embodiments of the present invention, in step S3, the heating rate of the third firing is 1-5°C / min. For example, it can be 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, or a range consisting of any two of the above values.

[0090] According to some embodiments of the present invention, in step S3, the temperature of the third firing is 300-600° C. For example, it can be 300° C., 350° C., 400° C., 450° C., 500° C., 550° C., 600° C., or a range consisting of any two of the above values.

[0091] According to some embodiments of the present invention, in step S3, the duration of the three burns is 5 to 12 hours, for example, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, or a range consisting of any two of the above values.

[0092] In the preparation method, the monocalcination, dicalcination, and tricalcination are all carried out in an oxygen-containing atmosphere. The oxygen concentration in the oxygen-containing atmosphere is ≥ 90%, for example, 92%, 95%, or a range consisting of any two of the above values.

[0093] According to an embodiment of the second aspect of the present invention, a lithium-ion battery is provided, which includes the high-nickel positive electrode material described in the embodiment of the first aspect of the present invention, or includes the high-nickel positive electrode material prepared by the preparation method described in the embodiment of the second aspect of the present invention.

[0094] Since the lithium-ion battery adopts all the technical solutions of the high-nickel positive electrode material or the preparation method of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments.

[0095] According to some embodiments of the present invention, the lithium-ion battery includes at least one of a button battery, a soft-pack battery, a square-shell battery, and a cylindrical battery.

[0096] According to some embodiments of the present invention, the lithium-ion battery is at least one of a symmetrical cell, a half cell, and a full cell.

[0097] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which: Figure 1 This is a cross-sectional SEM image of the high-nickel positive electrode material obtained in Example 1 of the present invention.

[0099] Figure 2 This is a cross-sectional SEM image of the high-nickel positive electrode material obtained in Example 8 of the present invention.

[0100] Figure 3 This is a cross-sectional SEM image of the high-nickel positive electrode material obtained in Comparative Example 1 of the present invention.

[0101] Figure 4 This is a graph showing the cycling results of the high-nickel positive electrode materials obtained in Example 1 of the present invention and Comparative Example 1.

[0102] Figure 5 This is a rate performance diagram of the high-nickel positive electrode material obtained in Example 1 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0103] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with the embodiments to fully understand the purpose, features and effects of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0104] In the description of the present invention, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the exemplary expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0105] Example 1 In this example, a high-nickel cathode material was prepared. The specific steps are as follows: S1. In an atmosphere with an oxygen concentration of 92%, according to the chemical formula of the target matrix material LiNi 0.888 Co 0.100 M 0.010 M´ 0.002 O2; mixing the precursor, lithium source and additive A and calcining to form a matrix material; Where M = Sr 0.001 Y 0.001 , M is Al, and the additive A contains M´; The precursor is Ni 0.90 Co 0.10 A mixture of (OH)2 and Al2O3, Ni 0.90 Co 0.10 (OH)2 had a D50 particle size of approximately 8.0 μm and a porosity of 6.8%, and was purchased from Jinchi Energy Company. Additive A was a mixture of strontium oxide and yttrium oxide. The lithium source was lithium hydroxide monohydrate, and the molar ratio of lithium element in the lithium salt to the precursor was 1.015:1. The first firing includes the first insulation platform and the second insulation platform in sequence; specifically, the temperature is first increased to 520°C at the first insulation platform at a heating rate of 3°C / min and kept warm for 4 hours; then the temperature is increased to 730°C at the second insulation platform at a heating rate of 2°C / min and kept warm for 11 hours.

[0106] S2 in an atmosphere of 92% oxygen concentration, the product obtained in step S1 and the additive B were mixed and sintered, cooled and sieved through a 325 mesh sieve to obtain a base material and a filling material filled in the pores inside the base material; Additive B is a mixture of zirconium oxide and tungstic acid, and the addition amounts of the two are calculated according to the addition concentrations 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.

[0107] The second firing includes heating to a holding platform of 600°C at a rate of 3°C / min and then holding for 8 hours.

[0108] S3. In an atmosphere of 92% oxygen concentration, the product obtained in step S2 was mixed with additive C and then tri-calcined. After tri-calcination, the mixture was cooled, passed through a 325-mesh sieve, and demagnetized. The tri-calcination yielded a high-nickel positive electrode material with a coating layer, a particle size of 7.1 μm, and a porosity of 2.3%. The tri-calcination temperature was 450°C for 7 hours at a heating rate of 3°C / min. Additive C was a mixture of aluminum oxide and titanium oxide in a 1:1 mass ratio, and the amount added was 0.3% by mass relative to the product obtained in step S2.

[0109] Examples 2 to 8 respectively prepared a high-nickel positive electrode material, and the specific differences from Example 1 are shown in Table 1. Among them, the porosity of the precursor used in Example 8 is 8.9%, and it is purchased from Jinchi Energy Company.

[0110] Table 1 Some parameters of Examples 1 to 8

[0111] Comparative Example 1 This example prepares a high-nickel positive electrode material, which differs from Example 1 in that: In step S2, no additive B is added. Figure 3 As shown, the cross-sectional porosity of the high nickel positive electrode material particles is 3.2%.

[0112] Comparative Example 2 This example prepares a high-nickel positive electrode material, which differs from Example 1 in that: In step S2, the additive B is tungstic acid, and the amount of tungstic acid added is the same as that in Example 1.

[0113] Comparative Example 3 This example prepares a high-nickel positive electrode material, which differs from Example 1 in that: In step S2, the additive B is zirconium oxide, and the amount of zirconium oxide added is the same as that in Example 1.

[0114] Comparative Example 4 This example prepares a high-nickel positive electrode material, which differs from Example 1 in that: In step S1, the first insulation platform is not set, that is, the temperature is directly raised from room temperature to the constant temperature of 730° C. on the second insulation platform and kept warm for 11 hours.

[0115] Comparative Example 5 This example prepares a high-nickel positive electrode material, which differs from Example 1 in that: In step S1, additive A is not added.

[0116] Comparative Example 6 This example prepares a high-nickel positive electrode material, which differs from Example 1 in that: In step S2, the temperature of the second calcination is 750°C.

[0117] Comparative Example 7 This example prepares a high-nickel positive electrode material, which differs from Example 1 in that: In step S2, the temperature of the second calcination is 350°C.

[0118] Application Examples This example prepares a lithium-ion battery, specifically: The high nickel positive electrode material prepared in the embodiment or comparative example, the conductive agent SuperP, the binder polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP) were mixed and stirred uniformly in a mass ratio of 90:5:5 to prepare a positive electrode slurry (solid content of about 40%), which was coated on the current collector aluminum foil, dried at 105°C, and then rolled at room temperature to a surface density of 2.8 g / cm 3 to 3.3g / cm 3 , then punched and cut into φ14mm discs to make positive electrode sheets.

[0119] Button cells were assembled in a glove box. The sequence was "negative electrode shell - nickel foam - lithium sheet (φ18mm) - 8 drops of electrolyte - separator (φ22mm, 16μm thick) - 8 drops of electrolyte - positive electrode sheet - positive electrode shell." The electrolyte consisted of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) (EC:EMC:DMC volume ratio = 1:1:1), containing 1.0M LiPF6. The battery shell (positive and negative) was 24mm in size. The assembled button cell was placed in the mold of a hydraulic sealing machine (purchased from Shenzhen Kejing Zhida Technology Co., Ltd.), locked, and pressurized to >450kg / cm 2 , then unlock it and take out the sealed button battery, which is the lithium-ion battery obtained in this example.

[0120] Test Example 1 This example tests the morphology of the high nickel cathode materials obtained in the examples and comparative examples. The test method is ordinary scanning electron microscopy or cross-sectional scanning electron microscopy (SEM). The specific test results are as follows: Figures 1-3 As shown. Ordinary SEM test results show that the high-nickel positive electrode materials obtained in Example 1 and Comparative Example 1 are both secondary spherical. Due to the addition of the filling material, the porosity of Example 1 is lower than that of Comparative Example 1. In Example 8, due to the adjustment of the dosage of the dopant, the mechanism of calcination, and the use of a precursor with higher porosity, a hollow structure is generated in the high-nickel positive electrode material obtained in Example 8. Furthermore, the particle size distribution of the primary particles of the high-nickel positive electrode material obtained in the example is between 200 and 400 nm.

[0121] Test Example 2 This example tests the rate performance and cycle performance of the lithium-ion battery obtained in the application example.

[0122] The test method for cycle performance is as follows: At 25°C, use a blue electric test cabinet to test the charge and discharge cycle characteristics of the button battery, setting 1C = 195mA / g. Charge and discharge at 1C and 2C in the voltage range of 3.0V to 4.3V. Specifically, charge at a constant current of 1C to 4.3V, then charge at a constant voltage at 4.3V to a cutoff current of 0.02C, let it rest for 5 minutes, discharge at 2C to 3.0V, let it rest for 5 minutes, and record the charge and discharge capacity after the first cycle. Cycle as above in sequence, charge / discharge 50 times, and record the charge and discharge capacity after the 50th cycle. Cycle capacity retention (%) = (50th cycle discharge capacity / 1st cycle discharge capacity) × 100%.

[0123] The rate performance test method is as follows: Test button cells in a Blue Electric test cabinet at 25°C. Set 1C = 195mA / g and charge / discharge at 0.1C within the voltage range of 3.0V to 4.3V. Specifically, charge at a constant current of 0.1C to 4.3V, then charge at a constant voltage at 4.3V to a cutoff current of 0.02C, rest for 5 minutes, and discharge at 0.1C to 3.0V. Rest for 5 minutes, and record the charge and discharge capacity. Then, repeat this test at 0.2C, 0.5C, 1C, and 2C, record the charge and discharge capacity, and calculate the ratio of the reversible capacity at the 1C / 0.1C rate.

[0124] The test results of the above electrochemical performance are shown in Table 2 and Figures 4 and 5 shown.

[0125] Table 2 Electrochemical performance results of high nickel cathode materials obtained in Examples and Comparative Examples

[0126] The results in Table 2 show that by varying the parameters within the ranges provided by the present invention, excellent results can be achieved, with a 50-cycle cycle retention of ≥94% and a 1C / 0.1C rate performance of ≥90%. Due to these excellent results, the high-nickel cathode material provided by the present invention, or lithium-ion batteries containing such a high-nickel cathode material, are expected to find widespread application in energy storage technology, power batteries, and communications electronics.

[0127] Comparing the results of Example 1 and Comparative Examples 1 to 3, it can be seen that if Additive B is not added, or the type of Additive B is not within the range required by this application, the overall performance of the resulting high-nickel positive electrode material is significantly reduced. This shows that the interstitial filler in the present invention 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.

[0128] Comparison of Example 1 and Comparative Examples 4 to 7 shows that if the primary firing mechanism or the secondary firing mechanism is not within the scope of the present application, or if Additive A is not added, the overall performance of the resulting high-nickel positive electrode material is significantly reduced. This shows that in the preparation method of the present invention, the various conditions and the doping and filling materials have a significant synergistic effect.

[0129] While the embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to the embodiments described above. Various modifications may be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof may be combined with one another unless there is a conflict.

Claims

1. A high nickel cathode material, characterized in that The high nickel positive electrode material comprises: Matrix material, the chemical formula of the matrix material is 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, and M' is at least one of Y, Sr, La, B, Mg and Ti; and the matrix material has pores; a filling substance present inside the pores, the filling substance comprising a sintered substance derived from the additive B, 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.

2. The high nickel cathode material according to claim 1, characterized in that The high nickel positive electrode material also has a coating layer, The coating layer comprises a sintered product derived from the additive C, The additive C comprises an aluminum-containing compound and a titanium-containing compound.

3. The high nickel cathode material according to claim 1, characterized in that 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 2-16 μm.

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

5. The high-nickel cathode material according to any one of claims 1 to 3, characterized in that The concentration of the target element introduced by a 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 greater than 0 ppm; The target elements are Zr, W, Sb and Bi; And / or, the additive B is at least one of the following combinations: (a) Zirconium-containing compounds and tungsten-containing compounds; (b) zirconium-containing compounds, tungsten-containing compounds and antimony-containing compounds; (c) Zirconium-containing compounds, tungsten-containing compounds and bismuth-containing compounds.

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

7. The preparation method according to claim 6, characterized in that 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)2 and M-containing compounds, and a´+b´=1; (3) Ni a´´ Co b´´ M c´´ (OH)2 and M-containing compounds, and a´´+b´´+c´´=1.

8. The preparation method according to claim 6, characterized in that The preparation method further comprises the following steps after step S2: S3. The product obtained in step S2 and additive C are mixed and then calcined.

9. The preparation method according to any one of claims 6 to 8, characterized in that The preparation method satisfies at least one of the following conditions: (a) The first heat preservation platform maintains a constant temperature for 2 to 6 hours; (b) The second insulation platform is maintained at a constant temperature for 6 to 16 hours; (c) The duration of the second burning is 5 to 12 hours.

10. A lithium ion battery, characterized in that: 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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