Preparation method of ternary positive electrode material, ternary positive electrode material and lithium ion battery

Abstract

The application discloses a preparation method of a ternary positive electrode material, the ternary positive electrode material and a lithium ion battery, and aims to avoid the problem that a single crystal material and a polycrystal material are prepared respectively and then mixed to prepare a complex in the prior art, so as to prepare a high-energy-density positive electrode material. The method comprises the following steps: performing first sintering treatment and second sintering treatment on a mixture of a polycrystal ternary precursor and a lithium source; adding a first dopant in the first sintering treatment and / or adding a second dopant in the second sintering treatment; performing water washing on a product of the second sintering treatment, crushing the water-containing oxide by tumbling and / or vibration of a drying equipment, and obtaining dry oxides including single crystal oxides and polycrystal oxides; and performing third sintering treatment on a mixture of the dry oxides and a coating agent. The method can effectively improve the preparation efficiency and the compaction density of the high-energy-density ternary positive electrode material, and solve the problem of different lithium deintercalation efficiencies during charging and discharging caused by mixing.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery technology, and in particular to a method for preparing a ternary cathode material, the ternary cathode material, and a lithium-ion battery. Background Technology

[0002] With the deepening of the concept of sustainable development, higher requirements have been placed on the battery life and energy density of secondary energy storage batteries. Among the many types of secondary energy storage batteries, lithium-ion batteries are widely used due to their advantages of high energy density, small memory effect, and low loss during use (i.e., high stability).

[0003] To further improve the energy density of lithium-ion batteries, ternary cathode materials have gradually become a major research focus. However, ternary cathode materials suffer from low energy density. Currently, to improve the energy density of ternary cathode materials, especially their volumetric energy density, the common approach is to mix polycrystalline and single-crystal particles to increase the compaction density of the ternary cathode material, thereby improving the volumetric energy density. On the one hand, this method involves complex preparation steps because it requires the separate preparation of single-crystal and polycrystalline particles for mixing. On the other hand, the depth of insertion / extraction between single-crystal and polycrystalline particles differs significantly during the charging-discharging process of lithium batteries, and mixing single-crystal and polycrystalline particles can lead to a decrease in the discharge capacity of the ternary cathode material. Therefore, current technology lacks a method for efficiently preparing high-energy-density ternary cathode materials. Summary of the Invention

[0004] This application provides a method for preparing ternary cathode materials, ternary cathode materials, and lithium-ion batteries, in order to improve the preparation efficiency of high-energy-density ternary cathode materials.

[0005] In a first aspect, embodiments of this application provide a method for preparing a ternary cathode material, comprising:

[0006] A mixture comprising a polycrystalline ternary precursor and a lithium source is subjected to a first sintering treatment and a second sintering treatment in sequence; wherein a first dopant is added during the first sintering treatment and / or a second dopant is added during the second sintering treatment, and the first sintering temperature of the first sintering treatment is higher than the second sintering temperature of the second sintering treatment.

[0007] The product from the second sintering process was washed with water and filtered to obtain an aqueous oxide.

[0008] The aqueous oxides are dried using a drying device, and the aqueous oxides are crushed after being turned over and / or vibrated by the drying device to obtain dried oxides; wherein, the dried oxides include monocrystalline oxides and polycrystalline oxides;

[0009] The mixture of the dried oxide and the coating agent is subjected to a third sintering treatment to obtain a ternary cathode material; wherein the third sintering temperature of the third sintering treatment is lower than the second sintering temperature.

[0010] In this embodiment, by adding a first dopant and / or a second dopant, the second sintering product, after being washed with water to remove impurities, can be broken by vibration and / or tumbling of the drying equipment, thereby obtaining a mixture of single-crystal oxide and polycrystalline oxide. Furthermore, a coating agent is used to ensure that all polycrystalline oxides and the surface of the broken single-crystal oxides are coated with a coating layer, thus obtaining a mixture of single-crystal ternary cathode material and polycrystalline ternary cathode material with a coating layer. This avoids the step of separately preparing single-crystal cathode material and polycrystalline cathode material and then mixing them in the prior art, thereby effectively improving the preparation efficiency of high-energy-density ternary cathode material. In addition, since the single-crystal cathode material in this embodiment is obtained by crushing polycrystalline oxide, the single-crystal cathode material and polycrystalline cathode material prepared in this embodiment have the characteristic of similar primary particle size. This characteristic can effectively ensure that the lithium insertion / extraction rate of the single-crystal cathode material and the polycrystalline cathode material remains consistent during the charging-discharging process, avoiding the problems of inconsistent charging-discharging lithium insertion / extraction efficiency and low specific capacity caused by the large difference in primary particle size between the mixed single-crystal particles and polycrystalline particles in the prior art.

[0011] In one possible implementation, the mass of the first dopant element corresponding to the first dopant does not exceed 1.0% of the mass of the ternary cathode material.

[0012] In one possible implementation, the mass of the second dopant element corresponding to the second dopant does not exceed 1.5% of the mass of the ternary cathode material.

[0013] In one possible implementation, the ratio between the sum of the masses of the first dopant element and the second dopant element and the mass of the ternary cathode material is greater than 0, and the mass of the coating element corresponding to the coating agent is 0.01%-0.5% of the mass of the ternary cathode material.

[0014] In one possible implementation, the median particle size D of the volume distribution of the polycrystalline ternary precursor... v1 50 is 5.5-16 μm; and the particle size and volume distribution of the polycrystalline ternary precursor are... The range is 0.45-1.6 μm.

[0015] In one possible implementation, the median particle size D of the ternary cathode material's volume distribution... v2 50 is 5-15.5μm, and D v2 50 and D v1 The relationship between 50 and 0 is: 0 < K ≤ 0.8, where K = (Dv1 50-D v2 50) / D v2 50.

[0016] One possible implementation is the particle size and volume distribution of the ternary cathode material. It ranges from 0.5 to 2.5.

[0017] In one possible implementation, the ternary cathode material is a secondary particle composed of primary particles.

[0018] In one possible implementation, the ternary cathode material includes a monocrystalline cathode material and a polycrystalline cathode material, wherein the primary particle size of the monocrystalline cathode material and the polycrystalline cathode material is 0.05-2.5 μm.

[0019] In one possible implementation, the compaction density of the ternary cathode material under a pressure of 3.5T is 2.5-4.3 g / cm³. 3 .

[0020] In one possible implementation, the specific surface area of ​​the ternary cathode material is 0.2-1.3 m². 2 / g.

[0021] In one possible implementation, the loose packing density of the ternary cathode material is 0.5-2.7 g / cm³. 3 The tap density is 1.3-3.3 g / cm³. 3 .

[0022] In one possible implementation, the polycrystalline ternary precursor is selected from: molecules with the general formula Ni x Co y M 1-x-y The hydroxide of (OH)₂, with the general molecular formula Ni x Co y M 1-x-y CO3 carbonates and molecules with the general formula Ni x Co y M 1-x-y At least one of the oxides of O; wherein M is selected from at least one of Mn and Al, 0.60≤x≤0.98, 0≤y≤0.4, 0<1-xy≤0.25.

[0023] One possible implementation is that the ternary cathode material has the following general molecular formula: Li n Ni a Co b M c N 1-a-b-cO2, wherein M is selected from at least one of Mn and Al, and N is a first dopant element, a second dopant element, and a coating element, wherein N is selected from at least one of Mg, Mo, Nb, Na, P, K, Ta, Te, Sr, Y, Ti, Zr, W, Sb, Al, Nb, B, and F, and 0.95≤n≤1.09, 0.60≤a≤0.98, 0≤b≤0.4, 0<c≤0.25, 0.0001<1-abc<0.03.

[0024] Secondly, embodiments of this application provide a ternary cathode material, comprising:

[0025] The general molecular formula of the ternary cathode material is: Li n Ni a Co b M c N d O2, the ternary cathode material includes polycrystalline cathode material and monocrystalline cathode material; the polycrystalline cathode material is composed of secondary particles formed by the aggregation of primary particles, and the monocrystalline cathode material is composed of particles obtained by crushing the secondary particles; the particle size of the primary particles is 0.05-2.5μm, and the compaction density of the ternary cathode material under 3.5T pressure is 2.5-4.3g / cm³. 3 ;in,

[0026] M is selected from at least one of Mn and Al, and N is the first doping element, the second doping element, and the coating element. The N is selected from at least one of Mg, Mo, Nb, Na, P, K, Ta, Te, Sr, Y, Ti, Zr, W, Sb, Al, Nb, B, and F, where 0.95≤n≤1.09, 0.60≤a≤0.98, 0≤b≤0.4, 0<c≤0.25, 0.0001<d<0.03, and a+b+c+d=1.

[0027] In one possible implementation, the loose packing density of the ternary cathode material is 0.5-2.7 g / cm³. 3 The tap density is 1.3-3.3 g / cm³. 3 .

[0028] In one possible implementation, the median particle size D of the ternary cathode material's volume distribution... v2 50 is 5-15.5 μm, and the particle size and volume distribution of the ternary cathode material are... It ranges from 0.5 to 2.5.

[0029] In one possible implementation, the specific surface area of ​​the ternary cathode material is 0.2-1.3 m². 2 / g.

[0030] In one possible implementation, the quantity distribution of the ternary cathode material is D n2 10 is 0.25-12.5μm, and D n2 50 is 0.35-14.0μm.

[0031] In one possible implementation, the N2 of the ternary cathode material quantity distribution is 0.5-2.0; wherein,

[0032] In one possible implementation, the average particle size of the single-crystal cathode material is less than 3 μm.

[0033] Thirdly, embodiments of this application also provide a lithium-ion battery, comprising:

[0034] Ternary cathode materials prepared by the method described in the first aspect and any possible implementation thereof.

[0035] In one possible implementation, the lithium-ion battery includes: a positive electrode, a negative electrode, and an electrolyte; wherein,

[0036] The positive electrode includes a positive current collector and a ternary positive electrode material coated on the side of the positive current collector facing the negative electrode; the negative electrode includes a negative current collector.

[0037] In one possible implementation, the positive current collector is aluminum foil, the negative current collector is graphite, and the electrolyte is composed of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. Attached Figure Description

[0038] Figure 1 A scanning electron microscope image of the synthetic embodiment 1 provided in this application;

[0039] Figure 2 A scanning electron microscope image of the synthetic embodiment 2 provided in this application;

[0040] Figure 3 Scanning electron microscope image of synthetic embodiment 3 provided in this application;

[0041] Figure 4 Scanning electron microscope image of synthetic embodiment 4 provided in this application;

[0042] Figure 5 A scanning electron microscope image of synthetic embodiment 5 provided in this application;

[0043] Figure 6 This is a scanning electron microscope image of the synthetic comparative example 1 provided in the embodiments of this application;

[0044] Figure 7The scanning electron microscope image of the synthetic comparative example 2 provided in the embodiments of this application;

[0045] Figure 8 The scanning electron microscope image of the synthetic comparative example 3 provided in the embodiments of this application;

[0046] Figure 9 The image shown is a scanning electron microscope (SEM) image of the synthetic comparative example 4 provided in the embodiments of this application. Detailed Implementation

[0047] To address the low efficiency of high-energy-density ternary cathode material preparation in existing technologies, this application proposes a method for preparing ternary cathode materials: A polycrystalline ternary precursor and a lithium source are mixed and sequentially subjected to a first sintering treatment, a second sintering treatment, followed by washing and drying. During the first sintering treatment, a first dopant is added, and / or during the second sintering treatment, a second dopant is added, causing the second sintering product to break down under the action of tumbling and / or vibration in a drying device to obtain a dried oxide. Subsequently, a mixture of the dried oxide and a coating agent is subjected to a third sintering treatment to obtain a ternary cathode material comprising both single-crystal and polycrystalline cathode materials. This preparation method, by adding the first and / or second dopant, reduces the grain boundary strength between primary particles in the second sintering product, thereby causing the second sintering product to break down under the action of vibration and / or tumbling in the drying device, obtaining a dried oxide comprising both polycrystalline and single-crystal oxides, and thus obtaining a high-energy-density ternary cathode material. Therefore, the method for preparing ternary cathode materials provided in this application avoids the complicated steps of preparing single-crystal oxides and polycrystalline oxides separately in the prior art, and effectively improves the preparation efficiency of high-energy-density ternary cathode materials.

[0048] To better understand the above technical solutions, the technical solutions of this application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of this application and the specific features in the embodiments are detailed descriptions of the technical solutions of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0049] Please refer to Figure 1 This application proposes a method for preparing ternary cathode materials to improve the preparation efficiency of high-energy-density ternary cathode materials. The method specifically includes the following steps:

[0050] Step 101: The mixture including the polycrystalline ternary precursor and the lithium source is subjected to a first sintering treatment and a second sintering treatment in sequence.

[0051] Wherein, a first dopant is added during the first sintering process, and / or a second dopant is added during the second sintering process, and the first sintering temperature of the first sintering process is higher than the second sintering temperature of the second sintering process.

[0052] In the first sintering process, the first sintering temperature can be 600-850℃, and the first sintering time can be 5-20h.

[0053] In the second sintering process, the second sintering temperature can be 450-700℃, and the second sintering time can be 5-20h.

[0054] Furthermore, the first dopant and the second dopant may be the same or different. The first dopant and the second dopant are each independently selected from one or more substances containing the following elements: Mg, Mo, Nb, Na, P, K, Ta, Te, Sr, Y, Ti, Zr, W, Sb, Al, Nb, B, and F. These substances may be oxides, fluorides, or hydroxides.

[0055] Furthermore, the aforementioned polycrystalline precursor is selected from: molecules with the general formula Ni x Co y M 1-x-y The hydroxide of (OH)₂, with the general molecular formula Ni x Co y M 1-x-y CO3 carbonates and molecules with the general formula Ni x Co y M 1-x-y At least one of the oxides of O; wherein M is selected from at least one of Mn and Al, 0.60≤x≤0.98, 0≤y≤0.4, 0<1-xy≤0.25.

[0056] The median grain size D of the volume distribution of the polycrystalline ternary precursor v1 The particle size distribution (SPAN1) of the polycrystalline ternary precursor is 5.5-16 μm. Furthermore, the particle size distribution (SPAN1) of the SPAN1 precursor is 0.45-1.6 μm. The expression for SPAN1 is...

[0057] Furthermore, the amount (mass) of the first dopant added corresponds to the ratio of the mass of the first dopant element to the mass of the target product. In one embodiment of this application, the mass of the first dopant element does not exceed 1.0% of the mass of the ternary cathode material.

[0058] The amount (mass) of the second dopant added corresponds to the ratio of the mass of the second dopant element to the mass of the target product. In one embodiment of this application, the mass of the second dopant element does not exceed 1.5% of the mass of the ternary cathode material.

[0059] Furthermore, since the second sintering temperature is lower than the first sintering temperature, during the second sintering process, the second dopant corresponding to the second dopant is only partially doped into the first sintering product. The remaining second dopant is enriched in the surface layer of the first sintering product and reacts with lithium ions (Li) on the surface. + A chemical reaction occurs, forming a coating layer, thus obtaining a second sintered product with a coating layer.

[0060] For example, if the second doping element is boron (B), then the second sintering product is an inner layer material doped with trace amounts of boron, and the coating layer includes an oxide of lithium borate (Li3BO3).

[0061] It is worth noting that the ratio between the sum of the masses of the first and second doping elements and the mass of the ternary cathode material is greater than 0.

[0062] Furthermore, the lithium source can be lithium hydroxide or lithium carbonate. The molar ratio between the lithium source and the polycrystalline ternary precursor is 0.96:1-1.1:1.

[0063] Step 102: Wash and filter the product of the second sintering treatment to obtain water-containing oxides.

[0064] The water content of the hydrated oxide does not exceed 10%. This water content indicates the ratio between the difference between the mass of the hydrated oxide and the mass of the dried oxide and the mass of the hydrated oxide.

[0065] Specifically, to avoid insufficient lithium content in the target product due to the volatilization of the lithium source during high-temperature sintering, this application embodiment adds an excess of lithium source to ensure that the lithium content in the target product is the target lithium content. However, the addition of an excess lithium source often leads to a high lithium content on the surface of the sintered product. For example, both the first and second sintered products have high residual alkali content due to the adhesion of lithium carbonate or lithium hydroxide on the surface. Therefore, a water washing step is used to remove residual alkali and other impurities adhering to the surface of the second sintered product.

[0066] Furthermore, after washing, a large amount of water in the second sintering product after washing can be initially removed by filtration, thereby obtaining a water-containing oxide with a low water content (not exceeding 10%). For example, vacuum filtration.

[0067] Therefore, the above filtration can also be replaced by centrifugation, that is, using a centrifuge to achieve solid-liquid separation and obtain aqueous oxides with a water content of no more than 10%. Specifically, the centrifugation time should not exceed 20 minutes, and the vibration frequency should be less than 20Hz to avoid damaging the structure of the aqueous oxides.

[0068] Step 103: Dry the water-containing oxide using a drying device, causing the water-containing oxide to be broken after being turned over and / or vibrated by the drying device to obtain dried oxide.

[0069] The dried oxides include single-crystal oxides and / or polycrystalline oxides.

[0070] Specifically, the drying equipment can be a double cone dryer, a plow dryer, a centrifugal spray dryer, a vibrating dryer, a drum dryer, or a disc dryer, etc.

[0071] The drying time can be 3-10 hours, and the drying temperature can be 80-160℃.

[0072] The introduction of the first dopant and / or the second dopant effectively reduces the interfacial stress and grain boundary strength between primary particles in the corresponding product due to the presence of the first dopant element and / or the second dopant element, thereby causing the second sintered product to break after washing and drying.

[0073] Before crushing, the particles were polycrystalline oxides, and after crushing, they were monocrystalline oxides. The specific capacity of these monocrystalline oxides was higher than or equal to that of the polycrystalline oxides, thereby increasing the specific capacity of the product from the second sintering treatment.

[0074] Furthermore, since the volume of single-crystal oxide is smaller than that of polycrystalline oxide, the single-crystal oxide obtained from crushing can fill the gaps between polycrystalline oxides, thereby increasing the packing density of the dried oxide and obtaining a high-density dried oxide.

[0075] Step 104: Perform a third sintering treatment on the mixture of the dried oxide and the coating agent to obtain a ternary cathode material.

[0076] The third sintering temperature of the third sintering process is lower than the second sintering temperature.

[0077] In the third sintering process, the third sintering temperature can be 200-600℃, and the third sintering time is 5-20h.

[0078] The mixture of the above-mentioned dry oxide and coating agent can be obtained by a vertical high-speed mixer.

[0079] Specifically, water washing can remove impurities adhering to the surface of the sintered product, but it also damages the coating layer of the sintered product to some extent. In addition, the breakage of some dried oxides in step 103 also leads to incomplete coating layers on the surface of the dried oxides. Therefore, a third sintering treatment is performed on the dried oxides and coating agent to ensure that the surface of the obtained ternary cathode material has a coating layer, thereby ensuring the lithium-ion insertion / extraction efficiency of the ternary cathode material.

[0080] The coating agent described above may be the same as or different from either the first or second dopant. The coating agent may be selected from one or more substances containing the following elements: Mg, Mo, Nb, Na, P, K, Ta, Te, Sr, Y, Ti, Zr, W, Sb, Al, Nb, B, F. Alternatively, it may be selected from one or more substances containing the following elements: Mo, Nb, Ta, Te, Sr, Y, Ti, Zr, W, Al, B, F.

[0081] The aforementioned substances can be oxides, fluorides, or hydroxides.

[0082] Furthermore, the mass of the coating element corresponding to the coating agent is 0.01%-0.5% of the mass of the target ternary cathode material. The third sintering temperature of the third sintering treatment is 450-700℃.

[0083] The general molecular formula of ternary cathode materials is: Li n Ni a Co b M c N 1-a-b-c O2, wherein M is selected from at least one of Mn and Al, N is a first doping element and / or a second doping element, and a coating element, wherein N is selected from at least one of Mg, Mo, Nb, Na, P, K, Ta, Te, Sr, Y, Ti, Zr, W, Sb, Al, Nb, B, and F, 0.95≤n≤1.09, 0.60≤a≤0.98, 0≤b≤0.4, 0<c≤0.25, 0.0001<1-abc<0.03.

[0084] The median particle size D of the volume distribution of this ternary cathode material v2 50 is 5-15.5μm, and D v2 50 and the median particle size D of the volume distribution of the polycrystalline ternary precursor v1 The relationship between 50 and 50 is: K = (D v1 50-D v2 50) / D v2 50, where 0 < K ≤ 0.8.

[0085] Furthermore, the particle size and volume distribution of the ternary cathode material SPAN2 It ranges from 0.5 to 2.5.

[0086] Furthermore, the quantity distribution D of polycrystalline ternary precursors n1 The thickness ranges from 0.3 to 13.0 μm. Correspondingly, the number distribution D of the ternary cathode material... n2 10 is 0.25-12.5μm.

[0087] Number distribution D of polycrystalline ternary precursorsn1 The thickness of 50 ranges from 0.4 to 14.5 μm. Correspondingly, the number distribution D of the ternary cathode material... n2 50 is 0.35-14.0μm.

[0088] make The N1 of the polycrystalline ternary precursor is 0.45-1.5. Correspondingly, the N2 of the ternary cathode material is 0.5-2.0.

[0089] It should be noted that the above-mentioned quantity distribution and volume distribution are different descriptions of the particle size of the polycrystalline ternary precursor and the ternary cathode material in the embodiments of this application. The following is an explanation of the volume distribution and quantity distribution.

[0090] Volume distribution is a cumulative measure of particulate matter volume. For example, the median particle size D under volume distribution. v The 50 specification states that when a batch of particulate matter is arranged in ascending order, the particle size is determined by the following condition: when the sum of the volumes of a particular particle and all particles preceding it accounts for 50% of the sum of the volumes of all other particles, the particle size is D. v 50.

[0091] Quantity distribution is accumulated in units of the number of particles. For example, D n The 50 indicator arranges all particulate matter in ascending order, with each particulate matter number corresponding to its position in the arrangement. When the number of a particular particulate matter accounts for 50% of the total number of particulate matter numbers, the particle size of that particulate matter is D. n 50.

[0092] Furthermore, the cross-sectional porosity of this ternary cathode material does not exceed 7%, for example, 0.3%.

[0093] Furthermore, the ternary cathode material prepared in this embodiment includes both monocrystalline and polycrystalline cathode materials. Since the monocrystalline cathode material in this embodiment is obtained by crushing polycrystalline cathode material, meaning both originate from the same polycrystalline precursor, the primary particle sizes of the monocrystalline and polycrystalline cathode materials prepared in this embodiment are similar, with each primary particle size ranging from 0.05 to 2.5 μm. Because the primary particle sizes of this ternary cathode material are similar (i.e., the difference in particle size between any two primary particles is no greater than 2.45 μm), the lithium insertion / extraction depth can be kept consistent during the charge-discharge process. This avoids the problem of inconsistent lithium insertion / extraction depths caused by the large difference in primary particle sizes between monocrystalline and polycrystalline particles when mixing them in the prior art, thereby improving the specific capacity of the ternary cathode material.

[0094] Furthermore, the compaction density of this ternary cathode material under a pressure of 3.5T is 2.5-4.3 g / cm³. 3 .

[0095] Furthermore, the specific surface area of ​​this ternary cathode material is 0.2-1.3 m². 2 / g.

[0096] Furthermore, the loose packing density of this ternary cathode material is 0.5-2.7 g / cm³. 3 The tap density is 1.3-3.3 g / cm³. 3 .

[0097] Furthermore, the intensity Cs corresponding to the crushing of the sample particles of this ternary cathode material is 30-200 MPa, and the peak area ratio of the 101 crystal plane and the 012 crystal plane in the XRD (X-ray diffractometer) of this ternary cathode material [I(101) / I(012)]^0.5 is not less than 1.5. Therefore, the ternary cathode material prepared in the embodiments of this application has the characteristic of structural stability.

[0098] Based on the same inventive concept, this application also provides a ternary cathode material. The general molecular formula of this ternary cathode material is: Li n Ni a Co b M c N d O2, the ternary cathode material includes polycrystalline cathode material and monocrystalline cathode material; the polycrystalline cathode material is composed of secondary particles formed by the aggregation of primary particles, and the monocrystalline cathode material is composed of particles obtained by crushing the secondary particles; the particle size of the primary particles is 0.05-0.3μm, and the compaction density of the ternary cathode material under 3.5T pressure is 2.5-4.3g / cm³. 3 .

[0099] Wherein, M is selected from at least one of Mn and Al, N is a first doping element and / or a second doping element, and a coating element, wherein N is selected from at least one of Mg, Mo, Nb, Na, P, K, Ta, Te, Sr, Y, Ti, Zr, W, Sb, Al, Nb, B, and F, 0.95≤n≤1.09, 0.60≤a≤0.98, 0≤b≤0.4, 0<c≤0.25, 0.0001<d<0.03, and a+b+c+d=1.

[0100] Furthermore, the average particle size of the single-crystal cathode material is less than 3 μm.

[0101] Furthermore, the loose packing density of this ternary cathode material is 0.5-2.7 g / cm³. 3The tap density is 1.3-3.3 g / cm³. 3 .

[0102] Furthermore, the median particle size D of this ternary cathode material v2 50 is 5-15.5μm; the particle size and volume distribution of the ternary cathode material is SPAN2. It ranges from 0.5 to 2.5.

[0103] Furthermore, the specific surface area of ​​this ternary cathode material is 0.2-1.3 m². 2 / g.

[0104] Furthermore, the quantity distribution D of ternary cathode materials n2 10 is 0.25-12.5μm, D n2 50 represents 0.35-14.0 μm. Let... The N2 content of the ternary cathode material is 0.5-2.0.

[0105] Based on the same inventive concept, this application also provides a lithium-ion battery, which includes the above-mentioned ternary cathode material.

[0106] Furthermore, the lithium-ion battery can be a pouch battery, comprising: a positive electrode, a negative electrode, and an electrolyte.

[0107] The positive electrode includes a positive current collector and a ternary positive electrode material coated on the side of the positive current collector facing the negative electrode; the positive current collector can be aluminum foil. The negative electrode includes a negative current collector, which can be graphite. The electrolyte is composed of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC).

[0108] Since the lithium-ion battery includes the aforementioned ternary cathode material, its energy density and cycle stability can be effectively improved.

[0109] In summary, the ternary cathode material provided in this application embodiment has at least the following advantages:

[0110] Firstly, the aforementioned ternary cathode materials, with a nickel content of 0.6-0.98%, possess the advantage of high specific capacity. Secondly, these ternary cathode materials exhibit high compaction density, thereby improving the corresponding volumetric energy density. Thirdly, these ternary cathode materials not only include heterogeneous single-crystal cathode materials and polycrystalline cathode materials, but also, due to the similar primary particle sizes of single-crystal and polycrystalline cathode materials, both ranging from 0.05-2.5 μm, meaning the particle size difference between any two primary particles does not exceed 2.45 μm, this ensures consistent lithium-ion insertion / extraction depth between the single-crystal and polycrystalline cathode materials, effectively improving the specific capacity and stability of the ternary cathode materials. Fourthly, in the prior art, the powder impedance of monocrystalline cathode materials is generally higher than that of polycrystalline cathode materials. However, the monocrystalline cathode material prepared in the embodiments of this application is obtained by crushing polycrystalline dry oxides. Therefore, the powder impedance of the monocrystalline cathode material is not higher than that of the polycrystalline cathode material, thereby effectively reducing the powder impedance of both monocrystalline and polycrystalline cathode materials, and thus effectively improving the DCR (Directive Current Resistance) performance of the ternary cathode material.

[0111] It should be noted that the above-mentioned powder resistance can be tested using a powder impedance tester under a pressure of 3.5KN. The powder resistance of the ternary cathode material in this embodiment is measured to be 100-6000 Ohm / cm.

[0112] The following provides a detailed description through synthesis examples 1-5, synthesis comparative examples 1-4, device examples 1-5, and device comparative examples 1-4.

[0113] Synthesis Example 1

[0114] S1, D v Ni, a ternary precursor with a thickness of 11 μm and a span of 1.2, has a molecular weight of 50. 0.9 Co 0.05 Mn 0.05 (OH)2, LiOH and titanium hydroxide are thoroughly mixed, and the resulting mixture is subjected to a first sintering treatment in a box furnace with a metered amount of oxygen introduced. The product of the first sintering treatment is then crushed by mechanical grinding to obtain the first sintered product.

[0115] The ratio of the total molar amount of metal elements in the ternary precursor to the molar amount of lithium elements in lithium hydroxide is 1.04:1, and the mass ratio of titanium hydroxide to the precursor is 0.0027. In the first sintering process, the first sintering temperature is 755℃, and the first sintering time is 12 hours.

[0116] S2. Using a vertical high-speed mixer, the first sintering product is mixed for 20 minutes to obtain a second mixture.

[0117] S3. In an atmosphere box furnace with a fixed amount of oxygen introduced, the second mixture is subjected to a second sintering treatment and then sieved to obtain the second sintered product.

[0118] The second sintering treatment involves a second sintering temperature of 600℃ and a second sintering time of 12 hours.

[0119] S4. Dissolve the second sintering product in deionized water, stir thoroughly with an electric stirrer, and then filter to obtain an aqueous oxide.

[0120] The mass ratio of water to the second sintered product was 1.2:1, the speed of the electric stirrer was 200 r / min, and the water washing time was 5 min.

[0121] S5. In the double cone dryer, centrifugation is used to separate the material from the water, thereby removing the water from the surface of the water-containing oxide and obtaining the dry oxide.

[0122] The drying parameters for the double cone dryer are: centrifugation time 30 min, drying temperature 120℃, and drying time 8 h.

[0123] S6. The dry oxide is mixed evenly with boric acid, and after a third sintering treatment in an oxygen atmosphere, it is sieved to obtain a ternary cathode material. Figure 1 This is a scanning electron microscope (SEM) image of the ternary cathode material. Figure 1 As shown, there are broken single-crystal particles near the secondary particles, and the size of these single-crystal particles does not exceed 3 micrometers.

[0124] The mass ratio of boric acid to ternary cathode material is 0.0025. The third sintering temperature is 270℃, and the third sintering time is 8 hours.

[0125] Synthesis Example 2

[0126] S1, D v Ni, a ternary precursor with a thickness of 11 μm and a span of 1.2, has a molecular weight of 50. 0.9 Co 0.05 Mn 0.05 (OH)2 and LiOH are thoroughly mixed. The resulting mixture is then subjected to a first sintering treatment in a box furnace with a metered amount of oxygen introduced into it. The product of the first sintering treatment is then crushed by mechanical grinding to obtain the first sintered product.

[0127] The ratio of the total molar amount of metal elements in the ternary precursor to the molar amount of lithium elements in lithium hydroxide is 1.04:1. The first sintering temperature of the first sintering treatment is 755℃, and the first sintering time is 12h.

[0128] S2. Using a vertical high-speed mixer, the first sintered product and titanium hydroxide are thoroughly mixed for 20 minutes to obtain the second mixture.

[0129] The mass ratio of titanium hydroxide to the first sintered product is 0.0026.

[0130] S3. In an atmosphere box furnace with a fixed amount of oxygen introduced, the second mixture is subjected to a second sintering treatment and then sieved to obtain the second sintered product.

[0131] The second sintering treatment involves a second sintering temperature of 600℃ and a second sintering time of 12 hours.

[0132] S4. Dissolve the second sintering product in deionized water, stir thoroughly with an electric stirrer, and then filter to obtain an aqueous oxide.

[0133] The mass ratio of water to the second sintered product was 1.2:1, the speed of the electric stirrer was 200 r / min, and the water washing time was 5 min.

[0134] S5. In the double cone dryer, centrifugation is used to separate the material from the water, thereby removing the water from the surface of the water-containing oxide and obtaining the dry oxide.

[0135] The drying parameters for the double cone dryer are: centrifugation time 30 min, drying temperature 120℃, and drying time 8 h.

[0136] S6. The dry oxide is mixed evenly with boric acid, and after a third sintering treatment in an oxygen atmosphere, it is sieved to obtain a ternary cathode material. Figure 2 This is a scanning electron microscope (SEM) image of the ternary cathode material. Figure 2 As shown, there are broken single-crystal particles near the secondary particles, and the size of these single-crystal particles does not exceed 3 micrometers.

[0137] The mass ratio of boric acid to dry oxide is 0.0025, the third sintering temperature is 270℃, and the third sintering time is 8h.

[0138] Synthesis Example 3

[0139] S1. A ternary precursor Ni with a Dv50 of 11 μm and a SPAN of 1.2. 0.9 Co 0.05 Mn 0.05 (OH)2 and LiOH are thoroughly mixed, and the resulting mixture is subjected to a first sintering treatment in an atmosphere box furnace with a fixed amount of oxygen introduced. The product of the first sintering treatment is then crushed by mechanical grinding to obtain the first sintered product.

[0140] The ratio of the total molar amount of metal elements in the ternary precursor to the molar amount of lithium elements in lithium hydroxide is 1.04:1. In the first sintering process, the first sintering temperature is 755℃ and the first sintering time is 12 hours.

[0141] S2. Using a vertical high-speed mixer, the first sintered product is mixed with niobium pentoxide for 20 minutes to obtain a second mixture.

[0142] The mass ratio of niobium pentoxide to the first sintered product is 0.0029.

[0143] In an atmosphere box furnace with a fixed amount of oxygen introduced, the second mixture is subjected to a second sintering treatment and then sieved to obtain the second sintered product.

[0144] The second sintering treatment involves a second sintering temperature of 600℃ and a second sintering time of 12 hours.

[0145] S4. Dissolve the second sintering product in deionized water, stir thoroughly with an electric stirrer, and then filter to obtain an aqueous oxide.

[0146] The mass ratio of water to the second sintered product was 1.2:1, the speed of the electric stirrer was 200 r / min, and the water washing time was 5 min.

[0147] S5. In the plow dryer, centrifugation is used to separate the material from the moisture, thereby removing the moisture from the surface of the water-containing oxide and obtaining the dried oxide.

[0148] The drying parameters for the plow dryer are: centrifugation time 30 min, drying temperature 120℃, and drying time 8 h.

[0149] S6. The dry oxide is mixed evenly with boric acid, and after a third sintering treatment in an oxygen atmosphere, it is sieved to obtain a ternary cathode material. Figure 3 This is a scanning electron microscope (SEM) image of the ternary cathode material. Figure 3 As shown, there are broken single-crystal particles near the secondary particles, and the size of these single-crystal particles does not exceed 3 micrometers.

[0150] The mass ratio of boric acid to ternary cathode material is 0.0025. The third sintering temperature is 270℃, and the third sintering time is 8 hours.

[0151] Synthesis Example 4

[0152] S1. The ternary precursor Ni with Dv50 of 11 μm and SPAN of 1.2 μm is used. 0.9 Co 0.05 Mn 0.05(OH)2 and LiOH are thoroughly mixed, and the resulting mixture is subjected to a first sintering treatment in an atmosphere box furnace with a fixed amount of oxygen introduced. The product of the first sintering treatment is then crushed by mechanical grinding to obtain the first sintered product.

[0153] The ratio of the total molar amount of metal elements in the ternary precursor to the molar amount of lithium elements in lithium hydroxide is 1.04:1. In the first sintering process, the first sintering temperature is 755℃ and the first sintering time is 12h.

[0154] S2. Using a vertical high-speed mixer, the first sintered product is mixed with zirconium dioxide for 20 minutes to obtain a second mixture.

[0155] The mass ratio of zirconium dioxide to the first sintered product is 0.0027.

[0156] S3. In an atmosphere box furnace with a fixed amount of oxygen introduced, the second mixture is subjected to a second sintering treatment and then sieved to obtain the second sintered product.

[0157] The second sintering treatment involves a second sintering temperature of 600℃ and a second sintering time of 12 hours.

[0158] S4. Dissolve the second sintering product in deionized water, stir thoroughly with an electric stirrer, and then filter to obtain an aqueous oxide.

[0159] The mass ratio of water to the second sintered product was 1.2:1, the speed of the electric stirrer was 200 r / min, and the water washing time was 5 min.

[0160] S5. In a vibrating dryer, the material and water are separated by centrifugation, thereby removing the water from the surface of the water-containing oxide and obtaining the dried oxide.

[0161] The drying parameters for the vibrating dryer are: centrifugation time 30 min, drying temperature 120℃, and drying time 8 h.

[0162] S6. The dry oxide is mixed evenly with boric acid, and after a third sintering treatment in an oxygen atmosphere, it is sieved to obtain a ternary cathode material. Figure 4 This is a scanning electron microscope (SEM) image of the ternary cathode material. Figure 4 As shown, there are broken single-crystal particles near the secondary particles, and the size of these single-crystal particles does not exceed 3 micrometers.

[0163] The mass ratio of boric acid to ternary cathode material is 0.0025. The third sintering temperature is 270℃, and the third sintering time is 8 hours.

[0164] Synthesis Example 5

[0165] S1, D v Ni, a ternary precursor with a thickness of 11 μm and a span of 1.2, has a molecular weight of 50. 0.9 Co 0.05 Al 0.05 (OH)2 and LiOH are thoroughly mixed, and the resulting mixture is subjected to a first sintering treatment in an atmosphere box furnace with a fixed amount of oxygen introduced. The product of the first sintering treatment is then crushed by mechanical grinding to obtain the first sintered product.

[0166] The ratio of the total molar amount of metal elements in the ternary precursor to the molar amount of lithium elements in lithium hydroxide is 1.04:1. The first sintering temperature for the first sintering treatment is 755℃, and the first sintering time is 12h.

[0167] S2. Using a vertical high-speed mixer, the first sintered product is mixed with niobium pentoxide for 20 minutes to obtain a second mixture.

[0168] The mass ratio of niobium pentoxide to the first sintered product is 0.0029.

[0169] S3. In an atmosphere box furnace with a fixed amount of oxygen introduced, the second mixture is subjected to a second sintering treatment and then sieved to obtain the second sintered product.

[0170] The second sintering treatment involves a second sintering temperature of 600℃ and a second sintering time of 12 hours.

[0171] S4. Dissolve the second sintering product in deionized water, stir thoroughly with an electric stirrer, and then filter to obtain an aqueous oxide.

[0172] The mass ratio of water to the second sintered product was 1.2:1, the speed of the electric stirrer was 200 r / min, and the water washing time was 5 min.

[0173] S5. In the drum dryer, centrifugation is used to separate the material from the moisture, thereby removing the moisture from the surface of the water-containing oxide and obtaining the dry oxide.

[0174] The drying parameters for the drum dryer are: centrifugation time 30 min, drying temperature 120℃, and drying time 8 h.

[0175] S6. The dried oxide and boric acid are mixed evenly, and then subjected to a third sintering treatment in an oxygen atmosphere, followed by sieving to obtain the ternary cathode material. Please refer to the scanning electron microscope image of this ternary cathode material. Figure 5 .like Figure 5 As shown, there are broken single-crystal particles near the secondary particles, and the size of these single-crystal particles does not exceed 3 micrometers.

[0176] The mass ratio of boric acid to dry oxide is 0.0025, the third sintering temperature is 270℃, and the third sintering time is 8h.

[0177] Synthetic Comparative Example 1

[0178] S1, D v Ni, a ternary precursor with a thickness of 11 μm and a span of 1.2, has a molecular weight of 50. 0.9 Co 0.05 Mn 0.05 (OH)2 and LiOH are mixed, and the resulting mixture is subjected to a first sintering treatment in a box furnace with a metered amount of oxygen introduced. The product of the first sintering treatment is then crushed by mechanical grinding to obtain the first sintered product.

[0179] The ratio of the total molar amount of metal elements in the ternary precursor to the molar amount of lithium elements in lithium hydroxide is 1.04:1. After thorough mixing, a first mixture is obtained. In the first sintering process, the first sintering temperature is 755℃ and the first sintering time is 12h.

[0180] S2. Using a vertical high-speed mixer, the first sintering product is mixed for 20 minutes to obtain a second mixture.

[0181] S3. In an atmosphere box furnace with a fixed amount of oxygen introduced, the second mixture is subjected to a second sintering treatment and then sieved to obtain the second sintered product.

[0182] The second sintering treatment involves a second sintering temperature of 600℃ and a second sintering time of 12 hours.

[0183] S4. Dissolve the second sintering product in deionized water, stir thoroughly with an electric stirrer, and then filter to obtain an aqueous oxide.

[0184] The mass ratio of water to the second sintered product was 1.2:1, the speed of the electric stirrer was 200 r / min, and the water washing time was 5 min.

[0185] S5. In the vibrating dryer, centrifugation is used to separate the material from the moisture, thereby removing the moisture from the surface of the water-containing oxide and obtaining the dried oxide.

[0186] The drying parameters for the vibrating dryer are: centrifugation time 30 min, drying temperature 120℃, and drying time 8 h.

[0187] S6. The dry oxide is mixed evenly with boric acid, and after a third sintering treatment in an oxygen atmosphere, it is sieved to obtain a ternary cathode material. Figure 6 This is a scanning electron microscope (SEM) image of the ternary cathode material. Figure 6As shown, there are no broken single-crystal particles near the secondary particles.

[0188] The mass ratio of boric acid to ternary cathode material is 0.0025. The third sintering temperature is 270℃, and the third sintering time is 8 hours.

[0189] Synthetic Comparative Example 2

[0190] S1, D v Ni, a ternary precursor with a thickness of 11 μm and a span of 1.2, has a molecular weight of 50. 0.9 Co 0.05 Mn 0.05 (OH)2 and LiOH are thoroughly mixed. The resulting mixture is then subjected to a first sintering treatment in a box furnace with a metered amount of oxygen introduced into it. The product of the first sintering treatment is then crushed by mechanical grinding to obtain the first sintered product.

[0191] The ratio of the total molar amount of metal elements in the ternary precursor to the molar amount of lithium elements in lithium hydroxide is 1.04:1. The first sintering temperature for the first sintering treatment is 755℃, and the first sintering time is 12h.

[0192] S2. Using a vertical high-speed mixer, the first sintered product is mixed with titanium hydroxide for 20 minutes to obtain a second mixture.

[0193] The mass ratio of titanium hydroxide to the first sintered product is 0.0026.

[0194] S3. In an atmosphere box furnace with a fixed amount of oxygen introduced, the second mixture is subjected to a second sintering treatment and then sieved to obtain the second sintered product.

[0195] The second sintering treatment involves a second sintering temperature of 600℃ and a second sintering time of 12 hours.

[0196] S4. Dissolve the second sintered product in deionized water, stir thoroughly, and filter to obtain an aqueous oxide.

[0197] The mass ratio of water to the second sintered product was 1.2:1, the rotation speed was 200 r / min, and the water washing time was 5 min.

[0198] S5. In an oven, the water-containing oxide is allowed to stand and dry to obtain a dry oxide.

[0199] The drying parameters were: centrifugation time 30 min, drying temperature 120℃, and drying time 8 h.

[0200] S6. The dry oxide is mixed evenly with boric acid, and after a third sintering treatment in an oxygen atmosphere, it is sieved to obtain a ternary cathode material. Figure 7This is a scanning electron microscope (SEM) image of the ternary cathode material. Figure 7 As shown, there are no broken single-crystal particles near the secondary particles.

[0201] The mass ratio of boric acid to dry oxide is 0.0025, the third sintering temperature is 270℃, and the third sintering time is 8h.

[0202] Synthetic Comparative Example 3

[0203] S1, D v Ni, a ternary precursor with a thickness of 11 μm and a span of 1.2, has a molecular weight of 50. 0.9 Co 0.05 Mn 0.05 (OH)2 and LiOH are thoroughly mixed, and the resulting mixture is subjected to a first sintering treatment in a box furnace with a metered amount of oxygen introduced. The product of the first sintering treatment is then crushed by mechanical grinding to obtain the first sintered product.

[0204] The ratio of the total molar amount of metal elements in the ternary precursor to the molar amount of lithium elements in lithium hydroxide is 1.04:1, and the mass ratio of titanium hydroxide to the precursor is 0.0027. In the first sintering process, the first sintering temperature is 755℃, and the first sintering time is 12 hours.

[0205] S2. Using a vertical high-speed mixer, the first sintering product is mixed for 20 minutes to obtain a second mixture.

[0206] The mixing time and parameters are the same as in other embodiments and comparative examples.

[0207] S3. In an atmosphere box furnace with a fixed amount of oxygen introduced, the second mixture is subjected to a second sintering treatment and then sieved to obtain the second sintered product.

[0208] The second sintering treatment involves a second sintering temperature of 600℃ and a second sintering time of 12 hours.

[0209] S4. Dissolve the second sintering product in deionized water, stir thoroughly with an electric stirrer, and then filter to obtain an aqueous oxide.

[0210] The mass ratio of water to the second sintered product was 1.2:1, the speed of the electric stirrer was 200 r / min, and the water washing time was 5 min.

[0211] S5. In an oven, the water-containing oxide is allowed to stand and dry to obtain a dry oxide.

[0212] The drying parameters were: centrifugation time 30 min, drying temperature 120℃, and drying time 8 h.

[0213] S6. The dried oxide and boric acid are mixed evenly, and then subjected to a third sintering treatment in an oxygen atmosphere, followed by sieving to obtain the ternary cathode material. Please refer to the scanning electron microscope image of this ternary cathode material. Figure 8 .like Figure 8 As shown, there are no broken single-crystal particles near the secondary particles.

[0214] The mass ratio of boric acid to dry oxide is 0.0025, the third sintering temperature is 270℃, and the third sintering time is 8h.

[0215] Synthetic Comparative Example 4

[0216] S1, D v Ni, a ternary precursor with a thickness of 11 μm and a span of 1.2, has a molecular weight of 50. 0.9 Co 0.05 Al 0.05 (OH)2 and LiOH are thoroughly mixed, and the resulting mixture is subjected to a first sintering treatment in an atmosphere box furnace with a fixed amount of oxygen introduced. The product of the first sintering treatment is then crushed by mechanical grinding to obtain the first sintered product.

[0217] The ratio of the total molar amount of metal elements in the ternary precursor to the molar amount of lithium elements in lithium hydroxide is 1.04:1. The first sintering temperature for the first sintering treatment is 755℃, and the first sintering time is 12h.

[0218] S2. Using a vertical high-speed mixer, the first sintering product is mixed for 20 minutes to obtain a second mixture.

[0219] S3. In an atmosphere box furnace with a fixed amount of oxygen introduced, the second mixture is subjected to a second sintering treatment and then sieved to obtain the second sintered product.

[0220] The second sintering treatment involves a second sintering temperature of 600℃ and a second sintering time of 12 hours.

[0221] S4. Dissolve the second sintering product in deionized water, stir thoroughly with an electric stirrer, and then filter to obtain an aqueous oxide.

[0222] The mass ratio of water to the second sintered product was 1.2:1, the rotation speed was 200 r / min, and the water washing time was 5 min.

[0223] S5. In the drum dryer, centrifugation is used to separate the material from the moisture, thereby removing the moisture from the surface of the water-containing oxide and obtaining the dry oxide.

[0224] The drying parameters for the drum dryer are: centrifugation time 30 min, drying temperature 120℃, and drying time 8 h.

[0225] S6. The dried oxide and boric acid are mixed evenly, and then subjected to a third sintering treatment in an oxygen atmosphere, followed by sieving to obtain the ternary cathode material. Please refer to the scanning electron microscope image of this ternary cathode material. Figure 9 .like Figure 9 As shown, there are no broken single-crystal particles near the secondary particles.

[0226] The mass ratio of boric acid to dry oxide is 0.0025, the third sintering temperature is 270℃, and the third sintering time is 8h.

[0227] The compaction densities of synthetic examples 1-5 and synthetic comparative examples 1-4 were tested using an automatic powder compaction density meter. The cylinder diameter was 9 mm, the cylinder height was 28 mm, and the pressure was 3.5 T.

[0228] The surface area (BET) of synthetic examples 1-5 and synthetic comparative examples 1-4 was tested using dynamic chromatography with a specific surface area analyzer.

[0229] The particle size was measured using a Malvern 2000 laser particle size analyzer, and the SPAN was calculated.

[0230] Please refer to Table 1 for specific test data and SPAN data.

[0231] Table 1

[0232]

[0233] As shown in Table 1, the synthesis examples 1-5 introduced doping elements during the first or second sintering treatment, and then crushed the second sintering product under the vibration and / or tumbling action of the drying equipment in the drying step after the second sintering treatment using a double cone dryer or other drying equipment. As a result, the SPAN, BET, and compaction density of the synthesis examples 1-5 were all higher than those of the synthesis comparative examples.

[0234] Device Examples 1-5, Device Comparative Examples 1-4

[0235] Device Examples 1-5 and Comparative Examples 1-4 used Synthesis Examples 1-5 and Comparative Examples 1-4 as the positive electrode materials, respectively. The preparation of Device Examples 1-5 and Comparative Examples 1-4 is described below:

[0236] First, the positive electrode material, conductive agent, binder, and oil-based solvent are mixed at a mass ratio of 94.5% to obtain a slurry. Then, this slurry is coated onto a positive electrode sheet made of aluminum foil (with an area of ​​160 cm²). 2 This results in a coating density of 0.014 g / cm³ on the positive electrode. 2Finally, using the positive electrode, negative electrode (artificial graphite), separator (PP / PE / PP), and electrolyte (1.0M LiPF6 EC / DMC / EMC (1:1:1 volume ratio) solution), an 800mAh soft-pack battery was assembled.

[0237] The discharge capacity (mAh / g) and capacity retention of devices in Examples 1-5 and Comparative Examples 1-41 were tested at 45℃ and 2.8-4.5V. Specific test data are shown in Table 2.

[0238] Table 2

[0239]

[0240] As shown in Table 2, since the cathode material of device examples 1-5 is a mixture of single-crystal cathode material and polycrystalline cathode material, the lithium-ion extraction and insertion efficiency of device examples 1-5 is effectively improved. The discharge capacity and cycle capacity retention rate of device examples 1-5 are higher than those of device comparative examples 1-4.

[0241] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing a ternary cathode material, characterized in that, include: A mixture comprising a polycrystalline ternary precursor and a lithium source is subjected to a first sintering treatment and a second sintering treatment in sequence; wherein a first dopant is added during the first sintering treatment and a second dopant is added during the second sintering treatment, and the first sintering temperature of the first sintering treatment is higher than the second sintering temperature of the second sintering treatment. The product from the second sintering process was washed with water and filtered to obtain an aqueous oxide. The aqueous oxide is dried using a drying device, and the aqueous oxide is broken up by turning and / or vibrating the drying device to obtain a dried oxide; wherein the dried oxide includes monocrystalline oxide and polycrystalline oxide, and the volume of the monocrystalline oxide is smaller than that of the polycrystalline oxide; The mixture of the dried oxide and the coating agent is subjected to a third sintering treatment to obtain a ternary cathode material; wherein the third sintering temperature of the third sintering treatment is lower than the second sintering temperature; The polycrystalline oxide is composed of secondary particles formed by the aggregation of primary particles, and the monocrystalline oxide is obtained by crushing the polycrystalline oxide.

2. The method as described in claim 1, characterized in that, The mass of the first dopant element corresponding to the first dopant does not exceed 1.0% of the mass of the ternary cathode material.

3. The method as described in claim 1, characterized in that, The mass of the second dopant element corresponding to the second dopant does not exceed 1.5% of the mass of the ternary cathode material.

4. The method according to any one of claims 1-3, characterized in that, The mass of the first dopant element corresponding to the first dopant does not exceed 1.0% of the mass of the ternary cathode material; the mass of the second dopant element corresponding to the second dopant does not exceed 1.5% of the mass of the ternary cathode material. The ratio between the sum of the masses of the first dopant element and the second dopant element and the mass of the ternary cathode material is greater than 0, and the mass of the coating element corresponding to the coating agent is 0.01%-0.5% of the mass of the ternary cathode material.

5. The method as described in claim 4, characterized in that, The median particle size D of the volume distribution of the polycrystalline ternary precursor v1 50 is 5.5-16μm; and the SPAN of the particle size distribution of the polycrystalline ternary precursor. The range is 0.45-1.6 μm.

6. The method as described in claim 5, characterized in that, The median particle size D of the volume distribution of the ternary cathode material v2 50 is 5-15.5μm, and D v2 50 and D v1 The relationship between 50 and 0 is: 0 < K ≤ 0.8; where K = (D v1 50-D v2 50) / D v2 50.

7. The method as described in claim 5, characterized in that, The primary particle size of the ternary cathode material is 0.05-2.5 μm.

8. The method as described in claim 5, characterized in that, The compaction density of the ternary cathode material under a pressure of 3.5T is 2.5-4.3 g / cm³. 3 .

9. The method as described in claim 1, characterized in that, The polycrystalline ternary precursor is selected from: Ni x Co y M 1-x-y The hydroxide of (OH)₂, with the general molecular formula Ni x Co y M 1-x-y CO3 carbonates and molecules with the general formula Ni x Co y M 1-x-y At least one of the oxides of O; wherein M is selected from at least one of Mn and Al, 0.60≤x≤0.98, 0≤y≤0.4, 0<1-xy≤0.

25.

10. The method as described in claim 9, characterized in that, The general molecular formula of the ternary cathode material is: Li n Ni a Co b M c N 1-a-b-c O2, wherein M is selected from at least one of Mn and Al, and N is a first dopant element, a second dopant element, and a coating element, wherein N is selected from at least one of Mg, Mo, Nb, Na, P, K, Ta, Te, Sr, Y, Ti, Zr, W, Sb, Al, Nb, B, and F, and 0.95≤n≤1.09, 0.60≤a≤0.98, 0≤b≤0.4, 0<c≤0.25, 0.0001<1-abc<0.

03.

11. A ternary cathode material, characterized in that, include: The general molecular formula of the ternary cathode material is: Li n Ni a Co b M c N d O2, the ternary cathode material includes polycrystalline cathode material and monocrystalline cathode material, the volume of the monocrystalline cathode material being smaller than that of the polycrystalline cathode material; the polycrystalline cathode material is composed of secondary particles formed by the aggregation of primary particles, and the monocrystalline cathode material is composed of particles obtained by crushing the secondary particles; the primary particle sizes of the monocrystalline cathode material and the polycrystalline cathode material are similar, with a particle size of 0.05-2.5 μm; the compaction density of the ternary cathode material under 3.5T pressure is 2.5-4.3 g / cm³. 3 ;in, M is selected from at least one of Mn and Al, N is a first doping element and / or a second doping element, and a coating element, wherein N is selected from at least one of Mg, Mo, Nb, Na, P, K, Ta, Te, Sr, Y, Ti, Zr, W, Sb, Al, Nb, B, and F, 0.95≤n≤1.09, 0.60≤a≤0.98, 0≤b≤0.4, 0<c≤0.25, 0.0001<d<0.03, and a+b+c+d=1.

12. The ternary cathode material as described in claim 11, characterized in that, The loose packing density of the ternary cathode material is 0.5-2.7 g / cm³. 3 The tap density is 1.3-3.3 g / cm³. 3 .

13. The ternary cathode material as described in claim 11, characterized in that, The median particle size D of the volume distribution of the ternary cathode material v2 50 is 5-15.5 μm, and the SPAN of the particle size distribution of the ternary cathode material is... It ranges from 0.5 to 2.

5.

14. The ternary cathode material as described in claim 11, characterized in that, The specific surface area of ​​the ternary cathode material is 0.2-1.3 m². 2 / g.

15. The ternary cathode material as described in claim 11, characterized in that, In the quantity distribution of the ternary cathode material, D n2 10 is 0.25-12.5μm, and D n2 50 is 0.35-14.0μm.

16. The ternary cathode material as described in claim 15, characterized in that, The quantity distribution of the ternary cathode material N 2 The value is 0.5-2.0; among which, .

17. The ternary cathode material according to any one of claims 11-16, characterized in that, The average particle size of the single-crystal cathode material is less than 3 μm.

18. A lithium-ion battery, characterized in that, include: The ternary cathode material prepared by the method according to any one of claims 1-10, or the ternary cathode material according to any one of claims 11-17.

19. The lithium-ion battery as described in claim 18, characterized in that, The lithium-ion battery comprises: a positive electrode, a negative electrode, and an electrolyte; wherein... The positive electrode includes a positive current collector and a ternary positive electrode material coated on the side of the positive current collector facing the negative electrode; the negative electrode includes a negative current collector.

20. The lithium-ion battery as described in claim 19, characterized in that, The positive electrode current collector is aluminum foil, the negative electrode current collector is graphite, and the electrolyte is composed of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate.

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