A positive electrode material, a preparation method and application thereof

Abstract

The application provides a positive electrode material, a preparation method and application thereof, wherein the positive electrode material has a particle size distribution width SPAN of 1.30-1.90, and contains an M element with an ionic radius greater than 0.075 nm; the positive electrode material has a layered structure, and a D104 of the positive electrode material is 60-75 nm, wherein the D104 is the size of a crystal grain perpendicular to a 104 diffraction peak crystal surface direction obtained by XRD (X-ray diffraction) testing. The positive electrode material is applied to a battery, which is beneficial to improving the energy density, cycle performance and safety of the battery.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to a cathode material, its preparation method, and its application. Background Technology

[0002] In recent years, to meet the ever-increasing demand for high energy density in lithium-ion batteries, cathode materials are developing towards higher nickel content and higher voltage. Higher Ni content leads to higher capacity; increasing voltage can improve both the capacity and the voltage plateau of the material. However, increasing the charging voltage also reduces the interfacial stability between the cathode material and the electrolyte, leading to increased side reactions and severely affecting the cycle performance of lithium-ion batteries. Therefore, how to balance improving battery energy density and cycle performance is a key research focus in this field.

[0003] To balance energy density and cycle performance in batteries, current methods primarily involve surface coating of the cathode material, single-crystallization, or the addition of electrolyte additives. For example, patent document CN114335547A discloses a high-rate ternary cathode material, its preparation method, and its application. This method involves first doping the precursor with elements, followed by element doping during two sintering processes. This reduces the contact between the material surface and the electrolyte, thereby improving the material's cycle performance. However, this method is cumbersome, costly, and difficult to scale up for mass production. Patent document CN111952585A discloses a high-compact-density rubidium-doped lithium-ion battery cathode material and its preparation method. This method increases the compaction density of the material through solid-state high-temperature calcination and grinding, and doping with rubidium / cesium ions. However, this solid-state calcination method makes it difficult to achieve uniform mixing of the materials, which is detrimental to the performance of the doped elements. Furthermore, both of these methods can only improve either the battery's energy density or cycle performance individually, and further improvements are needed to achieve a balance between both. Summary of the Invention

[0004] The cathode material provided by this invention, when applied to a battery, helps to improve the battery's energy density, cycle performance, and safety.

[0005] The present invention also provides a method for preparing a positive electrode material, which can produce the above-mentioned positive electrode material. Applying the positive electrode material to a battery can help improve the energy density, cycle performance and safety of the battery.

[0006] The present invention also provides a positive electrode sheet, which, by including the above-mentioned positive electrode material, is beneficial to improving the energy density, cycle performance and safety of the battery when applied to a battery.

[0007] The present invention also provides a battery that, due to including the above-mentioned positive electrode, has high energy density, excellent cycle performance and safety.

[0008] In a first aspect, the present invention provides a cathode material having a particle size distribution width (SPAN) of 1.30 to 1.90, and the cathode material comprising an element M, wherein the ionic radius of the element M is greater than 0.075 nm.

[0009] The cathode material has a layered structure, and the D104 of the cathode material is 60-75 nm. D104 is the size of the grains in the direction perpendicular to the 104 diffraction peak obtained by XRD diffraction testing.

[0010] The cathode material as described above, wherein the M element includes at least one element selected from Na, Ce, Sr, K, Ti, Rb, Ba, and Y.

[0011] The cathode material described above, wherein the cathode material is composed of primary particles and secondary particles; and / or,

[0012] The positive electrode material has an initial discharge capacity of not less than 200 mAh / g under conditions of 2.5~4.25V and 0.1C; and / or,

[0013] The first-efficiency of the cathode material is greater than 90%.

[0014] The cathode material described above, wherein the molecular formula of the cathode material is LiNi x Co y A Z M g N h O2; wherein, 0.6≤x≤1, 0<y≤0.4, 0<z≤0.4, 0<g≤0.05, 0≤h≤0.05, A includes at least one of Mn and Al; M is Na, Ce, Sr, Y, K, Ti, Rb, Ba; N is at least one of Ta, Nb, Ge, W, Zr, B, Ca, Mo.

[0015] The cathode material described above is obtained by sequentially sintering and vibrating a precursor, a lithium source, and a compound providing element M.

[0016] The positive electrode material as described above, wherein the vibration frequency of the vibration treatment is not less than 180 times / minute; and / or,

[0017] The vibration treatment temperature is 100~350℃; and / or,

[0018] The sintering temperature is 720~850℃.

[0019] A second aspect of the present invention provides a method for preparing the cathode material described in the first aspect, comprising the following steps: mixing a precursor, a lithium source, and a compound providing element M, and then sequentially subjecting the mixture to sintering and vibration treatment to obtain the cathode material.

[0020] In the preparation method described above, a precursor, a lithium source, and an additive are mixed to obtain a first mixture; the first mixture is subjected to a first sintering treatment to obtain an intermediate.

[0021] The intermediate is subjected to crushing, washing, and vibration treatment in sequence to obtain the positive electrode material.

[0022] In the preparation method described above, the precursor includes at least one of nickel cobalt manganese hydroxide and nickel cobalt aluminum hydroxide.

[0023] The preparation method described above further includes, after the vibration treatment, a second sintering treatment of the vibration treatment product and the compound providing N element to obtain the cathode material.

[0024] A third aspect of the present invention provides a positive electrode sheet, the positive electrode sheet comprising the positive electrode material described in the first aspect or a positive electrode material prepared by the preparation method described in the second aspect.

[0025] In a fourth aspect, the present invention provides a lithium-ion battery comprising the positive electrode sheet described in the third aspect.

[0026] The implementation of this invention has at least the following beneficial effects:

[0027] The cathode material provided by this invention, due to the large ionic radius of element M, is mainly doped onto the crystal surface, making the crystal surface smoother, improving fluidity, and enhancing particle dispersibility. Simultaneously, vibration treatment causes at least some secondary particles to split into primary particles, improving the particle size distribution of the cathode material. Furthermore, the particle size distribution width (SPAN) of the cathode material is limited to 1.30~1.90, further ensuring the particle size distribution. When this cathode material is coated onto the cathode current collector, primary particles are distributed in the gaps between secondary particles, which not only increases the compaction density of the powder and effectively improves the volumetric energy density of the battery, but also ensures more uniform stress on the particles, reducing the probability of breakage, reducing gas production, and improving the cycle performance and safety of the battery. Attached Figure Description

[0028] Figure 1 This is a SEM image (magnification 10K) of the positive electrode material in Embodiment 1 of the present invention.

[0029] Figure 2This is a SEM image (magnification 10K) of the positive electrode material in Embodiment 2 of the present invention.

[0030] Figure 3 This is a SEM image (magnification 10K) of the positive electrode material in Embodiment 3 of the present invention.

[0031] Figure 4 This is a SEM image (10K magnification) of the positive electrode material in Embodiment 4 of the present invention.

[0032] Figure 5 This is a SEM image (10K magnification) of the positive electrode material in Embodiment 5 of the present invention.

[0033] Figure 6 This is a SEM image (magnification 10K) of the cathode material of Comparative Example 1 of this invention.

[0034] Figure 7 This is a SEM image (magnification 10K) of the cathode material of Comparative Example 2 of this invention.

[0035] Figure 8 This is a SEM image (magnification 10K) of the cathode material of Comparative Example 3 of this invention.

[0036] Figure 9 This is a SEM image (magnification 10K) of the cathode material of Comparative Example 4 of this invention.

[0037] Figure 10 This is a SEM image (magnification 10K) of the cathode material of Comparative Example 5 of this invention.

[0038] Figure 11 This is a SEM image (10K magnification) of the positive electrode material in Embodiment 6 of the present invention.

[0039] Figure 12 This is a SEM image (10K magnification) of the positive electrode material in Embodiment 7 of the present invention.

[0040] Figure 13 This is a SEM image (10K magnification) of the positive electrode material in Embodiment 8 of the present invention.

[0041] Figure 14 This is a SEM image (magnification 10K) of the positive electrode material in Embodiment 9 of the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0043] In a first aspect, the present invention provides a cathode material having a particle size distribution width (SPAN) of 1.30 to 1.90, containing an element M with an ionic radius greater than 0.075 nm, having a layered structure, and having a density density (D104) of 60 to 75 nm, where D104 is the size of the grains in the direction perpendicular to the 104 diffraction peak obtained by XRD diffraction testing.

[0044] Since the ionic radius of element M is greater than 0.075 nm, element M will not enter the interior of the primary particles. Element M is mainly concentrated on the outer surface of the secondary particles and in the pores. This is beneficial to improving the crystallinity of the secondary particle surface. At the same time, the introduction of element M with a large ionic radius increases the surface anisotropy of the particles, making them easier to disperse in subsequent vibration treatment.

[0045] The cathode material of this invention is composed of multiple layered sheets with van der Waals forces between them, which can accommodate the insertion and extraction of lithium ions. This layered cathode material exhibits high ion transport efficiency and electrochemical performance.

[0046] According to XRD diffraction tests, the size of the grains in the cathode material of this invention, perpendicular to the crystal plane of the 104 diffraction peak, is 60-75 nm.

[0047] The cathode material provided by this invention is composed of primary particles and secondary particles. In some embodiments, the particle size distribution width (SPAN) of the cathode material is 1.30~1.90. The particle size distribution width of the cathode material essentially refers to the particle size distribution width of all primary and secondary particles in the cathode material. Specifically, the particle size distribution width of the cathode material is calculated using the formula (D90-D10) / D50, where D10 is the particle size corresponding to a cumulative volume distribution percentage of 10%; D50 is the particle size corresponding to a cumulative volume distribution percentage of 50%; and D90 is the particle size corresponding to a cumulative volume distribution percentage of 90%.

[0048] The present invention does not limit the testing methods for D90, D50, and D10 of the above-mentioned cathode materials. For example, a laser particle size analyzer can be used for measurement.

[0049] This invention does not limit the specific values ​​of D90, D50, and D10 of the cathode material, as long as the particle size distribution width of the cathode material is within the above-mentioned range. In some embodiments, the D90 of the cathode material is 17.0~21.0 μm; the D10 of the cathode material is 2.5~5.5 μm; and the D50 of the cathode material is 9.0~12.0 μm. By limiting the D90, D50, and D10 of the cathode material to the above-mentioned range, it is possible to achieve the desired particle size distribution width of the cathode material, improve the compaction density of the manufactured cathode sheet, and also ensure more uniform stress on the particles, avoiding particle cracking, which is beneficial to further improving the energy density, cycle performance, and safety of the battery.

[0050] According to the research of this invention, applying the above-mentioned cathode material to batteries is beneficial for simultaneously improving the energy density and cycle performance of the batteries. This is because, on the one hand, since the cathode material contains the M element with a large ionic radius, this M element is doped onto the crystal surface during sintering, making the crystal surface smoother and improving fluidity, which is beneficial for improving particle dispersibility and particle strength. On the other hand, by limiting the particle size distribution of the cathode material, it is beneficial to improve the compaction density of the cathode material. When this cathode material is coated on the cathode current collector, the primary particles can be distributed in the gaps between the secondary particles, which not only improves the compaction density of the powder and effectively improves the volumetric energy density of the battery, but also ensures that the stress on the particles is more uniform, reducing the probability of breakage, reducing gas production, and improving the cycle performance and safety of the battery.

[0051] This invention does not limit the specific type of element M, as long as the ionic radius of element M is greater than 0.075 nm. For example, in some embodiments, element M includes at least one element selected from Na, Ce, Sr, K, Ti, Rb, Ba, and Y. The cathode material is composed of primary particles and secondary particles; and / or,

[0052] In this invention, the initial discharge capacity of the cathode material under conditions of 2.5~4.25V and 0.1C is not less than 200mAh / g; and / or, the initial efficiency of the cathode material is greater than 90%; and / or, the ratio of I003 / I004 of the cathode material is 2.0~2.5, and the ratio of the relative intensities of the X-ray diffraction peak (003) and the X-ray diffraction peak (004) of the cathode material is labeled as I003 / I004.

[0053] Layered cathode materials are mainly lithium cobalt oxide and ternary materials. In some embodiments, the molecular formula of the cathode material of the present invention is LiNi. x Co y A Z M g N hO2; wherein, 0.6≤x≤1, 0<y≤0.4, 0<z≤0.4, 0<g≤0.05, 0≤h≤0.05, A includes at least one of Mn and Al; M is Na, Ce, Sr, Y, K, Ti, Rb, Ba; N is at least one of Ta, Nb, Ge, W, Zr, B, Ca, Mo.

[0054] In this invention, the cathode material is obtained by sequentially sintering and vibrating a precursor, a lithium source, and a compound providing element M. Sintering refers to transforming powdered materials into secondary particles. The precursor, lithium hydroxide, and the compound providing element M are mixed and then sintered to obtain a sintered product. The sintered product mainly consists of secondary particles composed of agglomerations of multiple primary particles. These secondary particles have a spherical or near-spherical shape, such as an ellipsoid. In this invention, vibration treatment refers to simultaneous vibration and drying. When the sintered product is vibrated, on the one hand, during vibration, at least some of the primary particles in the secondary particles are dispersed, which helps improve the particle size distribution of the cathode material and increase the compaction density of the cathode material powder; on the other hand, simultaneous drying during vibration improves production efficiency.

[0055] The precursor is either nickel cobalt manganese hydroxide (NCM) or nickel cobalt aluminum hydroxide (NCA).

[0056] By adjusting the parameters of the vibration treatment, it is beneficial to control the particle size distribution width of the cathode material. In some embodiments, the vibration frequency of the vibration treatment is not less than 180 times / minute.

[0057] This invention does not limit the vibration treatment temperature, as long as drying is achieved. In some embodiments, the vibration treatment temperature is 100~350℃. When the vibration treatment temperature is 100~200℃, the dried material can undergo a secondary sintering treatment to obtain a cathode material. When the vibration treatment temperature is 200~350℃, the secondary sintering treatment can be achieved during the vibration treatment process, and the dried material can be used directly as a cathode material.

[0058] This invention does not limit the sintering temperature, as long as it enables the sintering of the precursor, lithium source, and compound providing element M. In some embodiments, the sintering temperature is 720~850℃, for example, a range of 720℃, 750℃, 780℃, 800℃, 820℃, 850℃, or any combination thereof. By limiting the sintering temperature within the above range, it is advantageous to achieve a D104 of 60~75nm for the cathode material.

[0059] In a second aspect, the present invention provides a method for preparing a cathode material according to the first aspect, comprising the following steps: mixing a precursor, a lithium source, and a compound providing element M, and then sequentially subjecting the mixture to sintering and vibration treatment to obtain a cathode material.

[0060] The present invention does not limit the mixing method of the precursor, lithium source and additive. For example, in some embodiments, the precursor, lithium source and additive are mixed to obtain a first mixture; the first mixture is subjected to a first sintering treatment to obtain an intermediate; the intermediate is subjected to crushing treatment, water washing treatment and vibration treatment in sequence to obtain a cathode material.

[0061] The first sintering process is to transform the powdered material into a dense body (polycrystalline material); the crushing process is to crush the sintered product to prevent adhesion; and the water washing process is to remove residual powder from the surface of the sintered product.

[0062] This invention does not limit the specific parameters of the first sintering treatment and the vibration treatment. For example, the temperature of the first sintering treatment is 720~850℃, and the temperature of the vibration treatment is 100~350℃. Limiting the vibration treatment temperature to 100~350℃ is beneficial for removing residual moisture from the washing process. When the vibration treatment temperature is 100~200℃, the vibrated material can undergo a secondary sintering treatment to obtain the cathode material. When the vibration treatment temperature is 200~350℃, the coating material can be added directly at this temperature after the vibration treatment to achieve the secondary sintering treatment, without the need for secondary sintering and batching. The dried material can be used directly as the cathode material.

[0063] Vibration treatment can be carried out in vibration drying equipment, such as a vibration oven.

[0064] In some embodiments, after vibration treatment, a second sintering treatment is performed on the vibration treatment product and the compound providing N element to obtain a cathode material.

[0065] In the above embodiments, the second sintering process coats the surface of the vibration-treated product with a compound containing nitrogen (N). Because the vibration-treated product obtained by introducing nitrogen (M) and undergoing vibration treatment has excellent dispersibility, it facilitates the coating of N in the second sintering process, thereby improving coating uniformity and interfacial protection.

[0066] A third aspect of the present invention provides a positive electrode sheet, the positive electrode sheet comprising the positive electrode material of the first aspect or the positive electrode material prepared by the preparation method of the second aspect.

[0067] The positive electrode sheet of the present invention can also be prepared using conventional techniques in the art. Specifically, the above-mentioned positive electrode material, conductive agent, and binder can be uniformly dispersed in a solvent to obtain a positive electrode active layer slurry. Then, the positive electrode active layer slurry is coated on at least one functional surface of the positive electrode current collector, and after drying, the positive electrode sheet of the present invention can be obtained.

[0068] This invention does not specifically limit the types of conductive agents and adhesives. The conductive agents, adhesives and other components can all be conventional substances in the field. For example, the conductive agent can be selected from one or more of conductive carbon black, carbon nanotubes, conductive graphite and graphene, and the adhesive can be selected from one or more of polyvinylidene fluoride (PVDF), acrylic modified PVDF, polyacrylate polymers, polyimide, styrene-butadiene rubber and styrene-acrylic rubber.

[0069] The present invention does not specifically limit the coating method, and any coating method such as gravure coating, extrusion coating, spraying, screen printing, etc. can be used to achieve the coating of the positive electrode active layer slurry.

[0070] In a fourth aspect, this invention provides a lithium-ion battery, comprising the positive electrode provided in the third aspect. In addition to the positive electrode, the lithium-ion battery of this invention also includes a separator, a negative electrode, and an electrolyte. The composition of the negative electrode can refer to conventional negative electrode sheets in the art, and the separator can also be a separator conventionally used in the art, such as a PP film or a PE film.

[0071] The lithium-ion battery of the present invention can be prepared using conventional methods in the art. Specifically, the positive electrode, separator and negative electrode can be stacked in sequence, and the cell can be obtained by stacking or winding process. Then, the lithium-ion battery can be obtained by baking, liquid injection, formation and packaging.

[0072] The present invention will be further described below through specific embodiments and comparative examples.

[0073] Example 1

[0074] 1 kg of Ni precursor obtained by co-precipitation was added to a 2 L ball mill jar. 0.85 Co 0.06 Mn 0.09 (OH)2 was added to a 5L high-speed mixer at a lithiation coefficient molar ratio of 1:1.03, along with 465g of lithium hydroxide monohydrate and 1.23g of CeO2. The mixture was then added to the mixer and mixed at 350rpm for 15min. The mixture was then placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 760℃ at 2℃ / min, and sintered for 12h. After cooling to room temperature, the mixture was washed with 1:1 water for 10min, centrifuged at 1000rpm for 15min, and then dried in a vibrating oven at 140℃ with a vibration frequency of 200 times / min for 5h. The dried material and 2.5g of WO3 were added to a 2L high-speed mixer and mixed at 250rpm for 15min. After thorough mixing, the mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 320℃ at 2℃ / min, and sintered for 10h to obtain the cathode material LiNi. 0.847 Co 0.06 Mn0.09 Ce 0.001 W 0.002 O2.

[0075] Example 2

[0076] 1 kg of Ni precursor obtained by co-precipitation was added to a 2 L ball mill jar. 0.85 Co 0.06 Mn 0.09 (OH)2 was added to a 5L high-speed mixer at a lithiation coefficient molar ratio of 1:1.03, along with 465g of lithium hydroxide monohydrate and 2.54g of NaCl. The mixture was then mixed at 350rpm for 15min. The mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 760℃ at 2℃ / min, and sintered for 12h. After cooling to room temperature, the mixture was washed with 1:1 water for 10min, centrifuged at 1000rpm for 15min, and then dried in a vibrating oven at 140℃ with a vibration frequency of 200 times / min for 5h. The dried material and 2.5g of WO3 were added to a 2L high-speed mixer and mixed at 250rpm for 15min. After thorough mixing, the mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 320℃ at 2℃ / min, and sintered for 10h to obtain the cathode material LiNi. 0.847 Co 0.06 Mn 0.09 Na 0.001 W 0.002 O2.

[0077] Example 3

[0078] 1 kg of Ni precursor obtained by co-precipitation was added to a 2 L ball mill jar. 0.85 Co 0.06 Mn 0.09 (OH)2 was added to a 5L high-speed mixer at a lithiation coefficient molar ratio of 1:1.03, along with 465g of lithium hydroxide monohydrate and 1.91g of KCl. The mixture was then mixed at 350rpm for 15min. The mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 760℃ at 2℃ / min for 12h. After cooling to room temperature, the mixture was washed with 1:1 water for 10min, centrifuged at 1000rpm for 15min, and then dried in a vibrating oven at 140℃ with a vibration frequency of 200 times / min for 5h. The dried material and 2.5g of WO3 were added to a 2L high-speed mixer and mixed at 250rpm for 15min. After thorough mixing, the mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 320℃ at 2℃ / min and sintered for 10h to obtain the cathode material LiNi. 0.847 Co0.06 Mn 0.09 K 0.001 W 0.002 O2.

[0079] Example 4

[0080] 1 kg of Ni precursor obtained by co-precipitation was added to a 2 L ball mill jar. 0.85 Co 0.06 Mn 0.09 (OH)2 was added to a 5L high-speed mixer at a lithiation coefficient molar ratio of 1:1.03, along with 465g of lithium hydroxide monohydrate and 1.54g of CeF4. The mixture was then mixed at 350rpm for 15min, and the resulting material was placed in a crucible. An oxygen atmosphere (oxygen concentration ≥80%) was introduced into the crucible, and the temperature was raised to 760℃ at 2℃ / min for sintering for 12h. After cooling to room temperature, the mixture was washed with 1:1 water for 10min, centrifuged at 1000rpm for 15min, and then dried in a 140℃ vibrating oven at a vibration frequency of 200 times / min for 5h. The dried material and 2.5g of WO3 were added to a 2L high-speed mixer and mixed at 250rpm for 15min. After homogeneity, the mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was raised to 320℃ at 2℃ / min and sintered for 10h to obtain the cathode material LiNi. 0.847 Co 0.06 Mn 0.09 Ce 0.001 W 0.002 O2.

[0081] Example 5

[0082] 1 kg of Ni precursor obtained by co-precipitation was added to a 2 L ball mill jar. 0.85 Co 0.06 Mn 0.09 (OH)2 was added to a 5L high-speed mixer at a lithiation coefficient molar ratio of 1:1.03, along with 465g of lithium hydroxide monohydrate and 1.23g of CeO2. The mixture was then mixed at 350rpm for 15min. The mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 760℃ at 2℃ / min for 12h. After cooling to room temperature, the mixture was washed with 1:1 water for 10min, centrifuged at 1000rpm for 15min, and then dried in a 320℃ vibrating oven at a vibration frequency of 200 times / min for 3h. Finally, 2.5g of WO3 was added, and the mixture was continued to vibrate and dry for another 3h to obtain the cathode material LiNi. 0.847 Co 0.06 Mn 0.09 Ce 0.001 W 0.002 O2.

[0083] Example 6

[0084] 1 kg of Ni precursor obtained by co-precipitation was added to a 2 L ball mill jar. 0.85 Co 0.06 Mn 0.09 (OH)2 was added to a 5L high-speed mixer at a lithiation coefficient molar ratio of 1:1.03, along with 465g of lithium hydroxide monohydrate and 1.18g of SrO. The mixture was then mixed at 350rpm for 15min. The mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 760℃ at 2℃ / min for 12h. After cooling to room temperature, the mixture was washed with 1:1 water for 10min, centrifuged at 1000rpm for 15min, and then dried in a vibrating oven at 140℃ with a vibration frequency of 200 times / min for 5h. The dried material and 2.5g of WO3 were added to a 2L high-speed mixer and mixed at 250rpm for 15min. After thorough mixing, the mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 320℃ at 2℃ / min and sintered for 10h to obtain the cathode material LiNi. 0.847 Co 0.06 Mn 0.09 Sr 0.001 W 0.002 O2.

[0085] Example 7

[0086] 1 kg of Ni precursor obtained by co-precipitation was added to a 2 L ball mill jar. 0.85 Co 0.06 Mn 0.09 (OH)2 was added to a 5L high-speed mixer at a lithiation coefficient molar ratio of 1:1.03, along with 465g of lithium hydroxide monohydrate and 1.09g of Rb2O. The mixture was then added to the mixer and mixed at 350rpm for 15min. The mixture was then placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 760℃ at 2℃ / min, and sintered for 12h. After cooling to room temperature, the mixture was washed with 1:1 water for 10min, centrifuged at 1000rpm for 15min, and then dried in a vibrating oven at 140℃ with a vibration frequency of 200 times / min for 5h. The dried material and 2.5g of WO3 were added to a 2L high-speed mixer and mixed at 250rpm for 15min. After thorough mixing, the mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 320℃ at 2℃ / min, and sintered for 10h to obtain the cathode material LiNi. 0.847 Co 0.06 Mn 0.09 Rb 0.001 W 0.002O2.

[0087] Example 8

[0088] 1 kg of Ni precursor obtained by co-precipitation was added to a 2 L ball mill jar. 0.85 Co 0.06 Mn 0.09 (OH)2 was added to a 5L high-speed mixer at a lithiation coefficient molar ratio of 1:1.03, along with 465g of lithium hydroxide monohydrate and 0.90g of BaO. The mixture was then mixed at 350rpm for 15min. The mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 760℃ at 2℃ / min for 12h. After cooling to room temperature, the mixture was washed with 1:1 water for 10min, centrifuged at 1000rpm for 15min, and then dried in a vibrating oven at 140℃ with a vibration frequency of 200 times / min for 5h. The dried material and 2.5g of WO3 were added to a 2L high-speed mixer and mixed at 250rpm for 15min. After thorough mixing, the mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 320℃ at 2℃ / min and sintered for 10h to obtain the cathode material LiNi. 0.847 Co 0.06 Mn 0.09 Ba 0.001 W 0.002 O2.

[0089] Example 9

[0090] 1 kg of Ni precursor obtained by co-precipitation was added to a 2 L ball mill jar. 0.85 Co 0.06 Mn 0.09 (OH)2 was added to a 5L high-speed mixer at a lithiation coefficient molar ratio of 1:1.03, along with 465g of lithium hydroxide monohydrate and 1.28g of Y2O3. The mixture was then mixed at 350rpm for 15min. The mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 760℃ at 2℃ / min for 12h. After cooling to room temperature, the mixture was washed with 1:1 water for 10min, centrifuged at 1000rpm for 15min, and then dried in a vibrating oven at 140℃ with a vibration frequency of 200 times / min for 5h. The dried material and 2.5g of WO3 were added to a 2L high-speed mixer and mixed at 250rpm for 15min. After thorough mixing, the mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 320℃ at 2℃ / min and sintered for 10h to obtain the cathode material LiNi. 0.847 Co 0.06 Mn 0.09 Y 0.001 W0.002 O2.

[0091] Comparative Example 1

[0092] 1 kg of Ni precursor obtained by co-precipitation was added to a 2 L ball mill jar. 0.85 Co 0.06 Mn 0.09 (OH)2 was added to a 5L high-speed mixer at a lithium hydroxide monohydrate molar ratio of 1:1.03, and mixed at 350 rpm for 15 min. The mixture was then placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 760℃ at 2℃ / min for 12 h, and the mixture was cooled to room temperature. It was then washed with 1:1 water for 10 min, centrifuged at 1000 rpm for 15 min, and dried in a vibrating oven at 140℃ with a vibration frequency of 200 times / min for 5 h. The dried material and 2.5 g of WO3 were added to a 2L high-speed mixer and mixed at 250 rpm for 15 min. After thorough mixing, the mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 320℃ at 2℃ / min and sintered for 10 h to obtain the cathode material LiNi. 0.848 Co 0.06 Mn 0.09 W 0.002 O2.

[0093] Comparative Example 2

[0094] 1 kg of Ni precursor obtained by co-precipitation was added to a 2 L ball mill jar. 0.85 Co 0.06 Mn 0.09 (OH)2 was added to a 5L high-speed mixer at a lithiation coefficient molar ratio of 1:1.03, along with 465g of lithium hydroxide monohydrate and 1.66g of MgO. The mixture was then mixed at 350rpm for 15min. The mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 760℃ at 2℃ / min for 12h. After cooling to room temperature, the mixture was washed with 1:1 water for 10min, centrifuged at 1000rpm for 15min, and then dried in a vibrating oven at 140℃ with a vibration frequency of 200 times / min for 5h. The dried material and 2.5g of WO3 were added to a 2L high-speed mixer and mixed at 250rpm for 15min. After thorough mixing, the mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 320℃ at 2℃ / min and sintered for 10h to obtain the cathode material LiNi. 0.847 Co 0.06 Mn 0.09 Mg 0.001 W 0.002 O2.

[0095] Comparative Example 3

[0096] 1 kg of Ni precursor obtained by co-precipitation was added to a 2 L ball mill jar. 0.85 Co 0.06 Mn 0.09 (OH)2 was added to a 5L high-speed mixer at a lithiation coefficient molar ratio of 1:1.03, along with 465g of lithium hydroxide monohydrate and 1.23g of CeO2. The mixture was then added to the mixer and mixed at 350rpm for 15min. The mixture was then placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 760℃ at 2℃ / min for 12h. After cooling to room temperature, the mixture was washed with 1:1 water for 10min, centrifuged at 1000rpm for 15min, and then statically dried at 140℃ for 5h. The dried material and 2.5g of WO3 were added to a 2L high-speed mixer and mixed at 250rpm for 15min. After thorough mixing, the mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 320℃ at 2℃ / min and sintered for 10h to obtain the cathode material LiNi. 0.847 Co 0.06 Mn 0.09 Ce 0.00 1W 0.002 O2.

[0097] Comparative Example 4

[0098] 1 kg of Ni precursor obtained by co-precipitation was added to a 2 L ball mill jar. 0.85 Co 0.06 Mn 0.09 (OH)2 was added to a 5L high-speed mixer at a lithiation coefficient molar ratio of 1:1.03, along with 465g of lithium hydroxide monohydrate and 1.23g of CeO2. The mixture was then mixed at 350rpm for 15min. The mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 650℃ at 2℃ / min for 12h. After cooling to room temperature, the mixture was washed with 1:1 water for 10min, centrifuged at 1000rpm for 15min, and then dried in a vibrating oven at 140℃ with a vibration frequency of 200 times / min for 5h. The dried material and 2.5g of WO3 were added to a 2L high-speed mixer and mixed at 250rpm for 15min. After thorough mixing, the mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 320℃ at 2℃ / min and sintered for 10h to obtain the cathode material LiNi. 0.847 Co 0.06 Mn 0.09 Ce 0.001 W 0.002 O2.

[0099] Comparative Example 5

[0100] 1 kg of Ni precursor obtained by co-precipitation was added to a 2 L ball mill jar. 0.85 Co 0.06 Mn 0.09 (OH)2 was added to a 5L high-speed mixer at a lithiation coefficient molar ratio of 1:1.03, along with 465g of lithium hydroxide monohydrate and 1.23g of CeO2. The mixture was then added to the mixer and mixed at 350rpm for 15min. The mixture was then placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 880℃ at 2℃ / min for 12h. After cooling to room temperature, the mixture was washed with 1:1 water for 10min, centrifuged at 1000rpm for 15min, and then dried in a vibrating oven at 140℃ with a vibration frequency of 200 times / min for 5h. The dried material and 2.5g of WO3 were added to a 2L high-speed mixer and mixed at 250rpm for 15min. After thorough mixing, the mixture was placed in a crucible, and an oxygen atmosphere (oxygen concentration ≥80%) was introduced. The temperature was increased to 320℃ at 2℃ / min and sintered for 10h to obtain the cathode material LiNi. 0.847 Co 0.06 Mn 0.09 Ce 0.001 W 0.002 O2.

[0101] Test case

[0102] 1. Capacity test

[0103] The positive electrode material in the examples was assembled into a coin cell using the following method: The positive electrode material, acetylene black, and polyvinylidene fluoride (PVDF) were weighed at a mass ratio of 94:3:3, mixed evenly, and NMP was added and stirred for 2 hours to form a viscous slurry. This slurry was then evenly coated onto aluminum foil, vacuum baked at 80°C, pressed into sheets, and cut into positive electrode sheets with a diameter of 14 mm. A 16 mm diameter pure lithium sheet was used as the negative electrode, a 1 mol / L LiPF6 + DEC / EC (volume ratio 1:1) mixed solution was used as the electrolyte, and a polyCelgard propylene microporous membrane was used as the separator. The coin cells were then assembled into coin cells in an argon-filled glove box, and their capacity was tested.

[0104] 2. Circulation performance and gas production test

[0105] Gas production and cycle retention were tested using full-cell testing.

[0106] The positive electrode materials prepared in the above embodiments and comparative examples were respectively made into positive electrode sheets: the positive electrode material, conductive carbon black SP, conductive graphite KS-6, and binder PVDF were mixed in a mass ratio of 94.5%:2%:1%:2.5% NMP (N-methylpyrrolidone) to make a positive electrode slurry, and the positive electrode sheet was made by coating and rolling processes.

[0107] A 503048 full cell with a positive electrode, a negative electrode (graphite), a separator (polyCelgard propylene microporous membrane), and an electrolyte (1 mol / L LiPF6+DEC / EC (volume ratio 1:1)) was assembled and tested.

[0108] Cyclic performance test: Using the Xinwei test cabinet (CT3008-5V3A-A1), under 45℃ conditions, the cyclic voltage is 4.25~3V, the constant voltage cutoff current is 20mA, and the cycle is 300 times.

[0109] Gas production performance test: First, the battery is fully charged and the battery volume V1 is tested. Then, the fully charged battery is stored at 70°C for 7 days and the battery volume V2 is tested again. The gas production is (V2-V1) / V1×100%. The volume measurement device is an electronic solid density meter TW-120E.

[0110] The test results are shown in Table 1.

[0111] SEM images of the cathode materials in the examples and comparative examples are shown below. Figures 1 to 14 As shown.

[0112] Table 1

[0113]

[0114]

[0115] In the table, the ratio of the relative intensities of X-ray diffraction peak (003) and X-ray diffraction peak (004) is labeled as I003 / I004.

[0116] As shown in Table 1, the cathode material of the present invention is prepared by sintering and vibration treatment of precursor, lithium source and additive in sequence. The ionic radius of the doped element is greater than 0.075 nm and the D104 of the cathode material is 60-75 nm. When this cathode material is applied to a battery, the battery can have excellent energy density, cycle performance and safety.

[0117] Comparing Examples 1-9 and Comparative Examples 1-2, it can be seen that incorporating doping elements with ionic radii greater than 0.075 nm is beneficial to improving the cycle performance and safety of the battery.

[0118] Comparing Examples 1-9 with Comparative Example 3, it can be seen that vibration treatment can improve the particle size distribution width of the cathode material, while static drying methods are difficult to balance the energy density, cycle performance and safety of the battery.

[0119] Comparing Examples 1-9 and Comparative Examples 4-5, it can be seen that by adjusting the sintering temperature, it is beneficial to adjust the D104 value of the cathode material to be between 60 and 75 nm. If the temperature is too high or too low, the D104 value of the cathode material will not be in the range of 60 to 75 nm, which is not conducive to improving the electrochemical performance.

[0120] The preferred embodiments and experimental verifications of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A positive electrode material, characterized in that, The particle size distribution width (SPAN) of the cathode material is 1.39~1.90; the cathode material contains element M, and the ionic radius of element M is greater than 0.075 nm; The cathode material has a layered structure, and the D104 of the cathode material is 60-75 nm. D104 is the size of the grains in the direction perpendicular to the 104 diffraction peak obtained by XRD diffraction testing. The cathode material is composed of primary particles and secondary particles; the secondary particles are formed by the agglomeration of primary particles; the cathode material has a D90 of 17.0~21.0 μm, a D10 of 2.5~5.5 μm, and a D50 of 9.0~12.0 μm; the molecular formula of the cathode material is LiNi. x Co y A Z M g N h O2; wherein, 0.6≤x≤1, 0<y≤0.4, 0<z≤0.4, 0<g≤0.05, 0≤h≤0.05, A includes at least one of Mn and Al; M is at least one of Na, Ce, Sr, Y, K, Ti, Rb, and Ba; N is at least one of Ta, Nb, Ge, W, Zr, B, Ca, and Mo; The cathode material is obtained by sequentially sintering and vibrating a precursor, a lithium source, and a compound providing element M; the vibration frequency of the vibration treatment is not less than 180 times / minute; the vibration treatment temperature is 100~350℃; and the sintering temperature is 720~850℃.

2. The cathode material according to claim 1, characterized in that, The positive electrode material has an initial discharge capacity of not less than 200 mAh / g under conditions of 2.5~4.25V and 0.1C; and / or, The first-efficiency of the cathode material is greater than 90%.

3. A method for preparing the cathode material according to any one of claims 1-2, characterized in that, Includes the following steps: The precursor, lithium source, and compound providing element M are mixed and then subjected to sintering and vibration treatment in sequence to obtain the cathode material.

4. The preparation method according to claim 3, characterized in that, The precursor, lithium source, and additives are mixed to obtain a first mixture; the first mixture is subjected to a first sintering treatment to obtain an intermediate. The intermediate is subjected to crushing, washing, and vibration treatment in sequence to obtain the positive electrode material.

5. The preparation method according to claim 4, characterized in that, The precursor includes at least one of nickel cobalt manganese hydroxide and nickel cobalt aluminum hydroxide; and / or, Following the vibration treatment, a second sintering treatment is performed on the vibration treatment product and the compound providing N element to obtain the cathode material.

6. A positive electrode plate, characterized in that, The positive electrode sheet comprises the positive electrode material according to any one of claims 1-2 or the positive electrode material prepared by the preparation method according to any one of claims 3-5.

7. A lithium-ion battery, characterized in that, The lithium-ion battery includes the positive electrode sheet as described in claim 6.

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