Positive electrode active material and preparation method thereof, positive electrode plate, battery and electric equipment

Abstract

The invention provides a positive electrode active material and a preparation method thereof, a positive electrode plate, a battery and electric equipment, the 104 crystal face sub-grain size distribution of the positive electrode active material meets # imgabs 0 # imgabs 1 #, and Ln10, Ln50 and Ln90 are corresponding sub-grain sizes when the volume distribution cumulative percentages of the 104 crystal face sub-grain size Ln of the positive electrode active material reach 10%, 50% and 90% respectively. According to the positive electrode active material provided by the invention, the transmission path of lithium ions can be shortened, and the dynamic performance of the positive electrode active material is improved; and the crystallization degree of the positive electrode active material can be improved, the structural stability of the material is improved, the number of crystal boundaries in the positive electrode active material is reduced, the influence on lithium ion transmission is reduced, the positive electrode active material with excellent dynamic performance and structural stability is further obtained, and the high-temperature and low-temperature performance of the positive electrode active material is improved.

Description

Technical Field

[0001] This application relates to the field of batteries, and more particularly, to a positive electrode active material, a method for preparing the same, a positive electrode sheet, a battery, and an electrical device. Background Art

[0002] Nickel-cobalt-manganese positive electrode active materials are sought after for their excellent electrochemical performance. During the charge and discharge process of the positive electrode active material, lithium ions are frequently inserted and extracted between the positive and negative electrodes, resulting in changes in the material structure. Especially at high or low temperatures, the change in the structure of the positive electrode active material will be aggravated, leading to the deterioration of the electrical performance. Summary of the Invention

[0003] This application aims to solve at least one of the technical problems in the related art to some extent.

[0004] In a first aspect of this application, a positive electrode active material is provided, and the sub-grain size distribution of the 104 crystal plane of the positive electrode active material satisfies: Where Ln 10 , Ln 50 , Ln 90 are the sub-grain sizes corresponding to the cumulative volume percentages of the sub-grain sizes Ln of the 104 crystal plane of the positive electrode active material reaching 10%, 50%, and 90% respectively.

[0005] For the positive electrode active material provided in this application, by making the Ln 10 , Ln 50 , Ln 90 within the above range, on the one hand, the smaller sub-grain size can shorten the lithium ion transmission path and improve the kinetic performance of the positive electrode active material; on the other hand, it can improve the crystallinity of the positive electrode active material, improve the structural stability of the material, reduce the number of crystal boundaries in the positive electrode active material, and reduce the impact on lithium ion transmission. Furthermore, a positive electrode active material with both excellent kinetic performance and structural stability can be obtained, improving the high-temperature and low-temperature performance of the positive electrode active material.

[0006] According to some embodiments of this application, Thus, the kinetic performance and structural stability of the positive electrode active material are improved, and the high-temperature and low-temperature performance of the battery is improved.

[0007] According to some embodiments of this application, Kn 90 =(Ln 90 -Ln 10 ) / Ln 50 , and Kn 90 ≤1.8, optionally, 0 < Kn 90≤1.5. Thus, the uniformity of the positive electrode active material particles is improved, the lithium ion transmission rate is increased, and the kinetic performance of the positive electrode active material is improved.

[0008] According to some embodiments of the present application, the average particle size of the positive electrode active material particles is P 50 , and 1 μm ≤ P 50 ≤ 2.5 μm. Optionally, 1.3 μm ≤ P 50 ≤ 2 μm. Thus, while improving the particle size uniformity of the positive electrode active material particles, the adhesion between particles is reduced.

[0009] According to some embodiments of the present application, the volume distribution median particle size Dv of the positive electrode active material particles 50 satisfies 2 μm ≤ Dv 50 ≤ 4.5 μm. Optionally, 2.5 μm ≤ Dv 50 ≤ 4 μm. Thus, the lithium ion transmission path is shortened, and the kinetic performance of the positive electrode active material is improved.

[0010] According to some embodiments of the present application, 1 ≤ Dv 50 / P 50 ≤ 2.5. Optionally, 1.2 ≤ Dv 50 / P 50 ≤ 2.5. Thus, the agglomeration between the positive electrode active material particles is reduced.

[0011] According to some embodiments of the present application, the positive electrode active material includes a compound represented by Formula Ι:

[0012] Li 1±a (Ni x Co y Mn z G b )M c O2 Formula I,

[0013] wherein, 0 ≤ a ≤ 0.1, 0 ≤ b ≤ 0.05, 0 ≤ c ≤ 0.05, 0.4 ≤ x < 1, 0 < y < 0.5, 0 ≤ z < 0.5, G includes at least one of Zr, Ti, Y, W, Al, Nb, and M includes at least one of La, Zr, B, Nb, Ti, W, Si, Mg, Al, Co.

[0014] According to some embodiments of the present application, 0 < b ≤ 0.05. Thus, the structural stability of the positive electrode active material is improved by doping elements, and the high temperature performance of the battery is improved.

[0015] According to some embodiments of the present application, the positive electrode active material includes a matrix and a coating material located on at least a part of the surface of the matrix, and the coating material includes the M element. Thus, the structural stability of the positive electrode active material is improved.

[0016] The second aspect of the present application provides a method for preparing the positive electrode active material provided in the first aspect of the present application, and the method includes:

[0017] Mix a nickel-cobalt-manganese precursor and a lithium source to obtain a mixture;

[0018] Heat the mixture to a first constant temperature section and keep it warm. The temperature of the first constant temperature section is 600°C - 900°C. After the heat preservation ends, raise the temperature to conduct the first sintering on the mixture. The temperature of the first sintering is 800°C - 1000°C. After the first sintering ends, lower the temperature to a second constant temperature section. The temperature of the second constant temperature section is 300°C - 700°C and keep it warm to obtain an intermediate product;

[0019] Conduct a second sintering on the intermediate product. The temperature of the second sintering is less than or equal to the temperature of the first sintering to obtain the positive electrode active material.

[0020] In the method for preparing the positive electrode active material proposed by the present application, by controlling the temperatures of the first constant temperature section and the second constant temperature section, the growth process of sub-grains can be controlled, and further the sub-grain size Ln of the 104 crystal plane of the positive electrode active material can be controlled. 10 、Ln 50 、Ln 90 Thus, the structural stability of the positive electrode active material is improved, the distance of lithium ion transmission is shortened, and the high-temperature and low-temperature performance of the battery is improved.

[0021] According to some embodiments of the present application, the method further includes: mixing the nickel-cobalt-manganese precursor, the lithium source, and an additive containing the G element to obtain a mixture. Thus, the doping element can improve the structural stability of the positive electrode active material and improve the high-temperature performance of the battery.

[0022] According to some embodiments of the present application, when conducting the second sintering, mix the intermediate product with a coating agent containing the M element. Thus, the coating material can further improve the structural stability of the positive electrode active material.

[0023] According to some embodiments of the present application, the temperature of the second sintering is 300°C - 800°C.

[0024] According to some embodiments of the present application, the times of the first sintering and the second sintering are independently 6h - 12h respectively.

[0025] According to some embodiments of the present application, the additive includes at least one of an oxide containing element G, a hydroxide containing element G, and a carbonate containing element G.

[0026] The third aspect of the present application provides a positive electrode plate, including the positive electrode active material provided by the first aspect of the present application or the positive electrode active material prepared by the method provided by the second aspect of the present application.

[0027] The fourth aspect of the present application provides a battery, including the positive electrode plate provided by the third aspect of the present application.

[0028] The fifth aspect of the present application provides an electrical device, including the battery provided by the fourth aspect of the present application. Description of the Drawings

[0029] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description of the embodiments in conjunction with the accompanying drawings, where:

[0030] Figure 1 A schematic flow chart showing a method for preparing a positive electrode active material according to an embodiment of the present application.

[0031] Figure 2 An SEM image showing the positive electrode active material prepared in Example 1 of the present application.

[0032] Figure 3 An SEM image showing the positive electrode active material prepared in Comparative Example 1 of the present application.

[0033] Figure 4 A sub-grain size distribution diagram of the 104 crystal plane of the positive electrode active materials prepared in Example 1, Example 2, and Comparative Example 1 of the present application is shown. Detailed Description of Embodiments

[0034] Embodiments of the present application will be described in detail below. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application. For those not specified in the embodiments regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the field or according to the product specifications. For reagents or instruments not specified as to the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0035] The first aspect of the present application provides a positive electrode active material, and the sub-grain size distribution of the 104 crystal plane of the positive electrode active material satisfies: Where Ln 10 、Ln 50 、Ln 90 are the sub-grain sizes corresponding to the cumulative volume percentages of the sub-grain size Ln of the 104 crystal plane of the positive electrode active material reaching 10%, 50%, and 90% respectively.

[0036] The positive electrode active material proposed in this application, by making the Ln of the positive electrode active material 10 、Ln 50 、Ln 90 Within the above range, on the one hand, the smaller sub-grain size can shorten the transmission path of lithium ions and improve the kinetic performance of the positive electrode active material; on the other hand, it can improve the crystallization degree of the positive electrode active material, enhance the structural stability of the material, reduce the number of crystal boundaries in the positive electrode active material, and reduce the influence on the lithium ion transmission. Furthermore, a positive electrode active material with both excellent kinetic performance and structural stability can be obtained, improving the high-temperature and low-temperature performance of the positive electrode active material.

[0037] In this application, the sub-grain size Ln of the positive electrode active material is obtained by performing size statistics on the powder X-ray diffraction pattern measured by powder X-ray diffraction using CuKα radiation with the Fundamental Parameter method fitting algorithm.

[0038] As an example, Ln 10 can be etc., or can be a range composed of any of the above values.

[0039] As an example, Ln 50 can be etc., or can be a range composed of any of the above values.

[0040] As an example, Ln 90 can be etc., or can be a range composed of any of the above values.

[0041] According to some embodiments of the present application, By making Ln 10 、Ln 50 、Ln 90 Within the above range, it is possible to both shorten the transmission path of lithium ions and improve the crystallization degree of the positive electrode active material, enhance the structural stability of the positive electrode active material, thereby improving the high-temperature and low-temperature performance of the battery.

[0042] According to some embodiments of the present application, the positive electrode active material includes a compound represented by Formula Ι:

[0043] Li 1±a (Ni x Co y Mn z G b )M c O2 Formula I,

[0044] Among them, 0 ≤ a ≤ 0.1, 0 ≤ b ≤ 0.05, 0 ≤ c ≤ 0.05, 0.4 ≤ x < 1, 0 < y < 0.5, 0 ≤ z < 0.5, G includes at least one of Zr, Ti, Y, W, Al, and Nb, and M includes at least one of La, Zr, B, Nb, Ti, W, Si, Mg, and Al.

[0045] As an example, a can be 0, 0.03, 0.06, 0.08, 0.1, etc., or can be a range composed of any of the above numerical values.

[0046] As an example, b can be 0, 0.01, 0.02, 0.03, 0.04, 0.05, etc., or can be a range composed of any of the above numerical values.

[0047] According to some specific embodiments of the present application, 0 < b ≤ 0.05. By doping the G element in the positive electrode active material, the structural stability of the positive electrode active material can be improved, and the high-temperature performance of the battery can be improved.

[0048] As an example, c can be 0.01, 0.02, 0.03, 0.04, 0.05, etc., or can be a range composed of any of the above numerical values.

[0049] As an example, x can be 0.4, 0.6, 0.8, 0.9, 0.95, etc., or can be a range composed of any of the above numerical values.

[0050] As an example, y can be 0.1, 0.2, 0.3, 0.4, 0.45, etc., or can be a range composed of any of the above numerical values.

[0051] As an example, z can be 0, 0.1, 0.2, 0.3, 0.4, 0.45, etc., or can be a range composed of any of the above numerical values.

[0052] According to some embodiments of the present application, the positive electrode active material includes a matrix and a coating material located on at least a part of the surface of the matrix, and the coating material includes the M element. Thereby, the structural stability of the positive electrode active material is improved.

[0053] According to some embodiments of the present application, Kn 90 =(Ln 90 -Ln 10 ) / Ln 50 , and Kn 90 ≤1.8. In the present application, the magnitude of Kn 90 can reflect the uniformity of the grain distribution of the positive electrode active material. By making Kn 90 within the above range, the sub-grain size distribution of the 104 crystal plane of the positive electrode active material can be more concentrated and have better uniformity, and the influence of lithium ion transport can be reduced.

[0054] As an example, Kn 90 can be 0.3, 0.5, 0.9, 1.3, 1.5, 1.8, etc., or can be a range composed of any of the above values.

[0055] According to some specific embodiments of the present application, 0 < Kn 90 ≤ 1.5.

[0056] According to some embodiments of the present application, the average particle size of the positive electrode active material particles is P 50 , and satisfies 1 μm ≤ P 50 ≤ 2.5 μm. By making P 50 within the above range, on the one hand, the lithium ion transmission path can be shortened, and the low temperature performance of the battery can be improved; on the other hand, the adhesion between the positive electrode active material particles is reduced, which is beneficial to the formation of single crystal particles.

[0057] In the present application, the average particle size P 50 can be obtained by calculating the diameter after converting the projected area of 500 particles tested by a scanning electron microscope (SEM) into an equal area standard circle, and then calculating the average value, which is the average particle size of the positive electrode active material particles.

[0058] As an example, P 50 can be 1 μm, 1.3 μm, 1.7 μm, 2 μm, 2.3 μm, 2.5 μm, etc., or can be a range composed of any of the above values.

[0059] According to some specific embodiments of the present application, 1.3 μm ≤ P 50 ≤ 2 μm.

[0060] According to some embodiments of the present application, the median volume diameter Dv50 of the positive electrode active material particles satisfies 2 μm ≤ Dv 50 ≤ 4.5 μm. Thereby, the lithium ion transmission path is shortened, and the low temperature performance of the battery is improved.

[0061] In the present application, Dv 50 can be obtained by testing with a laser particle size analyzer of the Mastersizer 3000 model of Marvern Company.

[0062] According to some specific embodiments of the present application, 2.5 μm ≤ Dv 50 ≤ 4 μm.

[0063] According to some embodiments of the present application, 1 ≤ Dv 50 / P 50 ≤ 2.5. By making Dv 50 / P 50When the ratio is within the above range, the agglomeration of the positive electrode active material is reduced. During the battery cycling process, the risk of deterioration of the high-temperature cycle of the battery caused by the exposure of new interfaces due to the dispersion of the agglomerated particles is reduced.

[0064] According to some specific embodiments of the present application, 1.2 ≤ Dv 50 / P 50 ≤ 2.5.

[0065] The second aspect of the present application provides a method for preparing a nickel cobalt manganese positive electrode active material, and the method includes:

[0066] Mixing a nickel cobalt manganese precursor and a lithium source to obtain a mixture;

[0067] Heating the mixture to a first constant temperature section and keeping it warm. The temperature of the first constant temperature section is 600°C - 900°C. After the heat preservation ends, the temperature is raised to perform the first sintering on the mixture. The temperature of the first sintering is 800°C - 1000°C. After the first sintering ends, the temperature is lowered to a second constant temperature section. The temperature of the second constant temperature section is 300°C - 700°C and keep it warm to obtain an intermediate product;

[0068] Performing a second sintering on the intermediate product, and the temperature of the second sintering is less than or equal to the temperature of the first sintering to obtain the positive electrode active material.

[0069] In the method for preparing the positive electrode active material proposed by the present application, in the first constant temperature section, the lithium salt is melted at a lower temperature and penetrates into the interior of the precursor to make the raw materials fully contact, so that uniform sub-seeds are formed inside and outside the precursor. Then, the temperature is raised to perform the first sintering to grow the sub-seeds into sub-grains. Then, the heat preservation of the second constant temperature section is carried out to improve and repair the sub-grain defects and improve the uniformity of the sub-grains, so as to obtain a positive electrode active material with controllable sub-grain size distribution and uniform size distribution. The positive electrode active material obtained thereby has better structural stability and shorter lithium ion transmission distance, which can improve the kinetic performance and stability of the positive electrode active material and improve the high-temperature and low-temperature performance of the battery.

[0070] The method proposed by the present application will be described in detail below. Refer to Figure 1 , and the method includes:

[0071] S10: Mixing a nickel cobalt manganese precursor and a lithium source to obtain a mixture

[0072] In this step, the nickel cobalt manganese precursor and the lithium source are mixed by a high-speed mixer to obtain a uniform mixture. The stirring speed of the high-speed mixer can be 300 rpm - 500 rpm, and the stirring time can be 20 min - 40 min.

[0073] According to some embodiments of the present application, the nickel-cobalt-manganese precursor, lithium source, and additive containing element G can also be mixed using a high-speed mixer.

[0074] According to some embodiments of the present application, the additive includes at least one of an oxide containing element G, a hydroxide containing element G, and a carbonate containing element G.

[0075] During the sintering process, the nickel-cobalt-manganese precursor grows to form single crystals under the action of lithium salt. Adding an additive containing element G, element G can enter the material lattice and affect the orientation of the material. The sub-grain size of the additive in the present application is similar to it, which can improve the structural stability of the cathode active material.

[0076] According to some embodiments of the present application, the nickel-cobalt-manganese precursor includes at least one of nickel-cobalt-manganese oxide or nickel-cobalt-manganese hydroxide.

[0077] S20: Heat the mixture to the first constant temperature section and keep it warm. The temperature of the first constant temperature section is 600°C - 900°C. After the heat preservation ends, raise the temperature to perform the first sintering on the mixture. The temperature of the first sintering is 800°C - 1000°C. After the first sintering ends, lower the temperature to the second constant temperature section. The temperature of the second constant temperature section is 300°C - 700°C and keep it warm to obtain an intermediate product.

[0078] In this step, in an air or oxygen atmosphere, heat and raise the temperature of the mixture in a kiln. The internal pressure of the kiln is slightly positive, with a pressure of 0 - 30 Pa. Raise the temperature to the first constant temperature section at a rate of 1°C / min - 4°C / min. The temperature of the first constant temperature section is 600°C - 900°C, and keep it warm for 2 h - 4 h. Then raise the temperature at the same heating rate to perform the first sintering. The temperature of the first sintering is 800°C - 1000°C. After the first sintering ends, lower the temperature to the second constant temperature section. The temperature of the second constant temperature section is 300°C - 700°C, and keep it warm for 2 h - 4 h. After the heat preservation ends, lower the temperature to room temperature and crush it with a jet mill. The rotational speed of the classification wheel of the jet mill is 40 Hz - 50 Hz to obtain an intermediate product.

[0079] As an example, the temperature of the first constant temperature section can be 600°C, 700°C, 800°C, 900°C, etc., or can be a range composed of any of the above values.

[0080] As an example, the temperature of the first sintering can be 800°C, 900°C, 1000°C, etc., or can be a range composed of any of the above values.

[0081] According to some specific embodiments of the present application, the temperature of the first sintering can be 850°C - 980°C.

[0082] According to some embodiments of the present application, the time of the first sintering can be 6h - 12h. For example, it can be 6h, 8h, 10h, 12h, etc., or it can be a range composed of any of the above values.

[0083] By making the temperature and time of the first sintering within the above ranges, the above temperature is the suitable temperature and time for the reaction of the lithium salt and the precursor and the shaping of the positive electrode active material, and single crystal particles with good independence, roundness and fullness can be formed. If the temperature is too low, the reaction of the lithium salt and the precursor is incomplete or does not occur, and the obtained positive electrode active material still remains in an agglomerated or quasi-single crystal state, and it is difficult to form complete single crystal particles; if the temperature is too high, it will lead to an increase in processing costs, and at the same time, it is easy to over-sinter, resulting in too large an average particle size.

[0084] As an example, the temperature of the second constant temperature section can be 300°C, 400°C, 500°C, 600°C, 700°C, etc., or it can be a range composed of any of the above values.

[0085] S30: Perform a second sintering on the workpiece to be processed, and the temperature of the second sintering is less than or equal to the temperature of the first sintering to obtain the positive electrode active material

[0086] In this step, the workpiece to be processed is subjected to a second sintering in an air or oxygen atmosphere. The temperature of the second sintering is less than or equal to the temperature of the first sintering. The time of the second sintering can be 6h - 12h. After the second sintering is completed, it is sieved through a colloid mill or directly sieved to obtain a single crystal type positive electrode active material.

[0087] According to some embodiments of the present application, this step further includes: mixing the workpiece to be processed with a coating agent containing element M, and using a high-speed mixer for mixing. The stirring speed can be 300rpm - 600rpm, and the stirring time can be 20min - 40min.

[0088] In summary, the positive electrode active material and its preparation method proposed by the present application have the following advantages:

[0089] (1) By adding a first constant temperature section and a second constant temperature section in the process of preparing the positive electrode active material, the sub-grain size Ln of the 104 crystal plane of the positive electrode active material can be controlled 10 、Ln 50 、Ln 90 , and a positive electrode material with a uniform sub-grain size distribution is prepared, thereby improving the structural stability of the positive electrode active material, shortening the distance of lithium ion transmission, and improving the high temperature and low temperature performance of the battery.

[0090] (2) By controlling Dv of the positive electrode active material 50 and P 50 as well as Dv 50 / P50 , it can further shorten the transmission path of lithium ions, while reducing particle adhesion, thereby reducing the material impedance, improving the kinetic performance of the material, and improving the low-temperature performance of the battery.

[0091] (3) By doping element G in the positive electrode active material and / or forming a coating material containing element M on at least part of the surface of the matrix, the structural stability of the positive electrode active material can be improved, the probability of positive electrode particle cracking can be reduced, and the high-temperature performance of the battery can be improved.

[0092] The third aspect of the present application provides a positive electrode sheet, including the positive electrode active material provided in the first aspect of the present application or the positive electrode active material prepared by the method provided in the second aspect of the present application.

[0093] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer provided on at least one side of the positive electrode current collector, and the positive electrode active material layer includes the positive electrode active material provided in the first aspect of the present application.

[0094] The fourth aspect of the present application provides a battery, including the positive electrode sheet provided in the third aspect of the present application.

[0095] The shape of the battery can be a cylindrical battery, a square battery or any other shape battery, etc. Classified by outer packaging, the battery can be a hard-shell battery, a soft-pack battery, etc.

[0096] Generally, the battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator. Among them, the positive electrode sheet, the negative electrode sheet and the separator can be made into an electrode assembly through a winding or lamination process, and the electrode assembly and the electrolyte can be accommodated in the outer packaging. During the charge and discharge process of the battery, active ions are embedded and removed back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly playing a role in preventing short circuit between the positive and negative electrodes, and at the same time allowing ions to pass through.

[0097] The positive electrode sheet may include a positive electrode current collector and a positive electrode active substance layer provided on at least one side surface of the positive electrode current collector. The positive electrode active substance layer includes a positive electrode active material, a conductive agent and a binder. The positive electrode current collector may include a metal foil. For example, the metal foil may be made of aluminum foil. The positive electrode active material may include the positive electrode material of the first aspect of the present application or the positive electrode material prepared by the method described in the second aspect of the present application. The conductive agent may include acetylene black, single-walled carbon nanotubes and conventional materials in the art. The binder may be polyvinylidene fluoride (PVDF) and conventional materials in the art.

[0098] In some embodiments, the negative electrode tab can include a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector. The negative electrode active material layer can include a negative electrode active material, a thickener, a conductive agent, and a binder. Among them, the negative electrode current collector can be made of a metal foil. For example, the metal foil can be a copper foil. The negative electrode active material can include artificial graphite, natural graphite, silicon-containing carbon-based composite materials, lithium-containing metal composite materials, lithium metal materials, and common negative electrode active materials in the art. The thickener can be sodium carboxymethyl cellulose (CMC-Na) and conventional materials in the art. The conductive agent can be acetylene black and conventional materials in the art. The binder can be styrene-butadiene rubber and conventional materials in the art.

[0099] In some embodiments, the separator can be a separator well-known in the art that can be used in lithium-ion batteries and is stable to the electrolyte used, such as a polyethylene separator, a polypropylene separator, a polyethylene / polypropylene composite separator, etc.

[0100] A fourth aspect of the present application proposes an electrical device including the lithium-ion battery described in the third aspect of the present application. This electrical device has all the features and advantages of the aforementioned lithium-ion battery, which will not be elaborated herein one by one.

[0101] A fifth aspect of the present application provides an electrical equipment including the battery provided in the fourth aspect of the present application.

[0102] The electrical equipment can include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc., but is not limited thereto.

[0103] The embodiments of the present application will be described in detail below. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application. For those without specific technical or conditions noted in the embodiments, the techniques or conditions described in the literature in the art or according to the product specifications are followed. For reagents or instruments without the manufacturer noted, they are all conventional products that can be obtained through commercial purchases.

[0104] Example 1

[0105] Preparation of the positive electrode active material

[0106] Mix lithium carbonate, nickel cobalt manganese hydroxide precursor (Ni 0.6 Co 0.1 Mn 0.3 )(OH)2, additive ZrO2 (element G1 is Zr), additive Nb2O5 (element G2 is Nb) using a high-speed mixer, where n (Li): [n (Ni) + n (Co) + n (Mn) : n (G1) : n (G2) = 1.04:1:0.003:0.001, the high - speed mixer rotates at 400 rpm / min and mixes for 20 min;

[0107] The mixture is heated to 700 °C at a rate of 2.7 °C / min in an atmosphere with an oxygen content of over 90% and held for 3 h; after the holding, it is heated to 970 °C at a rate of 2.7 °C / min, and the sintering constant - temperature time is 8 h; then it is cooled to 500 °C at a rate of 2.7 °C / min and held for 3 h; after the end, the sintered material is crushed by a jet mill at a classifier wheel speed of 40 Hz to obtain an intermediate product;

[0108] The intermediate product is mixed with coating agent Al2O3 (M1 element is Al), coating agent Co3O4 (M2 element is Co) in the ratio of [n (Ni) + n (Co) + n (Mn) : n (M1) : n (M2) = 1:0.001:0.02 using a high - speed mixer, the high - speed mixer rotates at 500 rpm / min and mixes for 30 min; then it is sintered for the second time in an air atmosphere, the temperature of the second sintering is 700 °C, and the time is 9.5 h; after the sintering and discharging, the sintered material is crushed by a colloid mill to obtain the cathode active material Li 1.04 (Ni 0.58537 Co 0.11707 Mn 0.29268 Zr 0.00293 Nb 0.00098 )Al 0.00098 O2.

[0109] Example 2

[0110] The preparation process of the cathode active material is the same as that of Example 1, the difference is that the lithium salt is lithium hydroxide, the nickel - cobalt - manganese hydroxide precursor is (Ni 0.8 Co 0.1 Mn 0.1 )(OH)2, the temperature of the first sintering is adjusted to 900 °C, the constant - temperature time is 7 h, the temperature of the second sintering is 650 °C, and the holding time of the second sintering is 7 h. The chemical formula of the obtained cathode active material is Li 1.04 (Ni 0.78049 Co 0.11707 Mn 0.09756 Zr 0.00293 Nb 0.00098 )Al 0.00098 O2.

[0111] Example 3

[0112] The preparation process of the positive electrode active material is the same as that in Example 1, except that the temperature of the first sintering is 940 °C, the classification of the air jet mill is adjusted to 45 Hz, and the chemical formula of the prepared positive electrode active material is Li 1.04 (Ni 0.58537 Co 0.11707 Mn 0.29268 Zr 0.00293 Nb 0.00098 )Al 0.00098 O2.

[0113] Example 4

[0114] The preparation process of the positive electrode active material is the same as that in Example 1, except that the temperature of the first sintering is 940 °C, the additive Nb2O5 is replaced by Y2O3, the G2 element is Y, the coating agent Al2O3 is replaced by B2O3, the M1 element is B, and the chemical formula of the prepared positive electrode active material is Li 1.04 (Ni 0.58537 Co 0.11707 Mn 0.29268 Zr 0.00293 Y 0.00098 )B 0.00098 O2.

[0115] Example 5

[0116] The preparation process of the positive electrode active material is the same as that in Example 1, except that the temperature of the first sintering is 990 °C, and the chemical formula of the prepared positive electrode active material is Li 1.04 (Ni 0.58537 Co 0.11707 Mn 0.29268 Zr 0.00293 Nb 0.00098 )Al 0.00098 O2.

[0117] Example 6

[0118] The preparation process of the positive electrode active material is the same as that in Example 1, except that the temperature of the first sintering is 925 °C, the heat preservation time of the first sintering is 10 h, the classification of the air jet mill is adjusted to 45 Hz, and the chemical formula of the prepared positive electrode active material is Li 1.04 (Ni 0.58537 Co 0.11707 Mn 0.29268 Zr 0.00293 Nb 0.00098 )Al 0.00098 O2.

[0119] Example 7

[0120] The preparation process of the positive electrode active material is the same as that in Example 1, except that the temperature of the first constant temperature section is 650 °C, the temperature of the second constant temperature section is 350 °C, and the chemical formula of the prepared positive electrode active material is Li 1.04 (Ni 0.58537 Co 0.11707 Mn 0.29268 Zr 0.00293 Nb 0.00098 )Al 0.00098 O2.

[0121] Example 8

[0122] The preparation process of the positive electrode active material is the same as that in Example 1, except that the first sintering temperature is 920 °C and the airflow mill classification is 45 Hz. The chemical formula of the prepared positive electrode active material is Li 1.04 (Ni 0.58537 Co 0.11707 Mn 0.29268 Zr 0.00293 Nb 0.00098 )Al 0.00098 O2.

[0123] Example 9

[0124] The preparation process of the positive electrode active material is the same as that in Example 1, except that the first sintering temperature is 900 °C and the airflow mill classification is 45 Hz. The chemical formula of the prepared positive electrode active material is Li 1.04 (Ni 0.58537 Co 0.11707 Mn 0.29268 Zr 0.00293 Nb 0.00098 )Al 0.00098 O2.

[0125] Example 10

[0126] The preparation process of the positive electrode active material is the same as that in Example 1, except that the first constant temperature is 850 °C, the first sintering temperature is 900 °C, the second constant temperature section temperature is 600 °C, and the airflow mill classification is 45 Hz. The chemical formula of the prepared positive electrode active material is Li 1.04 (Ni 0.58537 Co 0.11707 Mn 0.29268 Zr 0.00293 Nb 0.00098 )Al 0.00098 O2.

[0127] Example 11

[0128] The preparation process of the positive electrode active material is the same as that in Example 1, except that the airflow mill classification is 35 Hz, and the chemical formula of the prepared positive electrode active material is Li1.04 (Ni 0.58537 Co 0.11707 Mn 0.29268 Zr 0.00293 Nb 0.00098 )Al 0.00098 O2。

[0129] Comparative Example 1

[0130] The preparation process of the positive electrode active material was the same as that of Example 1, except that the temperature of the first sintering was 780 °C.

[0131] Comparative Example 2

[0132] The preparation process of the positive electrode active material was the same as that of Example 1, except that the temperature of the first constant temperature section was 300 °C, the temperature of the first sintering was 900 °C, the temperature of the second constant temperature section was 725 °C, and the airflow mill classification was 45 Hz.

[0133] Comparative Example 3

[0134] The preparation process of the positive electrode active material was the same as that of Example 1, except that the temperature of the first constant temperature section was 945 °C and the temperature of the second constant temperature section was 245 °C.

[0135] The detailed differences among Examples 1 - 11 and Comparative Examples 1 - 3 are shown in Table 1.

[0136]

[0137] Performance Test

[0138] 1. Median volume diameter Dv 50 : Obtained by testing with a laser particle size analyzer of Mastersizer 3000 model from Malvern Company.

[0139] 2. Average particle size P 50

[0140] Obtained by testing with a scanning electron microscope of S - 4800 model from Hitachi, Japan. The projected area of each single crystal particle in the electron microscope was statistically analyzed, and then its particle size was calculated. The specific method was: the average diameter calculated by converting the projected areas of 500 random particles in the scanning electron microscope image into standard circular areas of equal area, that is, the average particle size P of the single crystal nickel - cobalt - manganese ternary positive electrode active material particles. 50 .

[0141] 3. Ln 10 、Ln 50 、Ln 90: Tested by a Rigaku Smartlab 9KW diffractometer, in the range of 10 - 80°, with a voltage of 40 kV, a current of 200 mA, a step of 0.02°, and a scanning time of 2° / min. The test results were obtained by statistically calculating the microcrystalline size using the WPPF grain size distribution function of SmartLab Studio II software according to the Fundamental Parameter method (FP method).

[0142] 4. Capacity Test

[0143] The electrochemical performance of CR2025 coin cells was tested using a Shenzhen Neware battery test system. The charge-discharge voltage range was controlled at 3.0 V - 4.4 V. At room temperature, the coin cells were charged and discharged at 0.1 C to evaluate the charge-discharge specific capacity of the single-crystalline nickel cobalt manganese ternary cathode material.

[0144] 5. High-temperature cycle capacity retention

[0145] In both the examples and comparative examples, the charge-discharge voltage range was controlled at 3.0 V - 4.4 V. At a constant temperature of 60 °C, the coin cells were charged and discharged at 0.1 C for 2 cycles, and then charged and discharged at 1 C for 80 cycles to evaluate the high-temperature cycle capacity retention of the single-crystalline nickel cobalt manganese ternary cathode material.

[0146] 6. Low-temperature performance test (the test voltage range for all lithium-ion batteries is 3.0 V - 4.4 V):

[0147] For the -10 °C 10% SOC - DCR test, after the coin cell was activated by charging and discharging at 1 C for 1 week at 25 °C, it was charged to 10% SOC at 1 C and then transferred to a -10 °C constant temperature chamber and left to stand for 2 h, followed by discharging at a current of 1 C for 20 s. The -10 °C 10% SOC - DCR is (the voltage at the last second of the standing step - the voltage after discharging for 20 s) / discharge current.

[0148] For the -10 °C 20% SOC - DCR test, after the coin cell was activated by charging and discharging at 1 C for 1 week at 25 °C, it was charged to 20% SOC at 1 C and then transferred to a -10 °C constant temperature chamber and left to stand for 2 h, followed by discharging at a current of 1 C for 20 s. The -10 °C 20% SOC - DCR is (the voltage at the last second of the standing step - the voltage after discharging for 20 s) / discharge current.

[0149] The test results of the positive electrode active materials and batteries in Examples 1 - 11 and Comparative Examples 1 - 3 are shown in Table 2.

[0150]

[0151] Comparing Examples 1 - 11 with Comparative Examples 1 - 3, it can be seen that the battery proposed in this application has both excellent high - temperature performance and low - temperature performance, indicating that by controlling Ln of the positive active material in this application 10 、Ln 50 、Ln 90 , a smaller sub - grain size can shorten the lithium - ion transport path, improve the kinetic performance of the positive active material. In addition, it can also improve the crystallization degree of the positive active material and enhance the structural stability of the material.

[0152] Comparing Examples 1 - 4 with Examples 5 - 11, it can be seen that by adjusting the sintering process of the positive active material, when Ln 10 、Ln 50 、Ln 90 of the prepared positive active material are all within the preferred range of this application, the high - temperature and low - temperature performance of the battery is better, indicating that the kinetic performance and structural stability of the positive active material are better.

[0153] Comparing Example 1 with Example 5, it can be seen that the average particle size P 50 in Example 1 is smaller, Ln 50 、Ln 90 are smaller, the lithium - ion transport ability is higher, and the capacity is higher.

[0154] Comparing Example 1 with Example 6, it can be seen that when the average particle size P 50 、Ln 50 、Ln 90 are controlled within the preferred range of this application, the lithium - ion transport rate can be further improved, the contact area between the positive active material and the electrolyte can be reduced, the occurrence of side reactions can be reduced, and the high - temperature cycle performance of the battery can be improved.

[0155] Comparing Example 1 with Example 7, it can be seen that the sub - grain size distribution of the positive active material in Example 1 is more concentrated, the difference in sub - grain size is smaller, which can improve the structural stability of the positive active material and the high - temperature cycle performance of the battery.

[0156] Comparing Example 1 with Example 11, it can be seen that when crushing the positive active material, crushing with a stronger strength will reduce Dv 50 of the positive active material, reduce the adhesion between the positive active material particles, reduce the exposure of new interfaces during the battery cycling process, and improve the performance of the battery.

[0157] From Comparative Example 1, it can be seen that if the temperature of the first sintering is too low, single - crystal particles cannot be formed, and it remains in a quasi - single - crystal state. Its average particle size and Ln50, Ln90 are all too small, resulting in the inability to fully exert the electrical performance.

[0158] It can be seen from Comparative Example 2 that if the temperature of the first constant temperature section is too low, it fails to play the role of melting the lithium salt to form sub-seeds, which is equivalent to directly entering the stage of growth of the second sub-seeds, resulting in poor uniformity of the sub-grain size distribution of the material.

[0159] It can be seen from Comparative Example 3 that if the temperature of the second constant temperature section is too low, it fails to play the role of repairing the defects of sub-grains, resulting in poor uniformity of the distribution of sub-grains, and further leading to the deterioration of electrical properties.

[0160] From the attached Figure 1 - attached Figure 3 It can be seen that the first sintering temperature of Comparative Example 1 is too low, resulting in an average particle size P 50 less than 1, and the sub-grain size is small. The cathode material particles do not form a single crystal morphology and still retain the characteristics of the precursor, resulting in difficulty in exerting the capacity; at the same time, due to a large Kn 90 value, the sub-grain size distribution is uneven and the structural stability is poor. Therefore, the high-temperature cycle retention rate is also poor.

[0161] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0162] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. A positive electrode active material, characterized in that: The 104 crystal plane subgrain size distribution of the positive electrode active material satisfies: Among them, Ln 10 , Ln 50 , Ln 90 The sub-grain sizes correspond to the cumulative percentages of the volume distribution of the crystal plane sub-grain size Ln of the positive electrode active material 104 reaching 10%, 50%, and 90%, respectively.

2. The positive electrode active material according to claim 1, characterized in that 3. The positive electrode active material according to claim 1 or 2, characterized in that: K 90 =(Ln 90 -Ln 10 ) / Ln 50 , and Kn 90 ≤1.8, optionally, 0<Kn 90 ≤1.

5.

4. The positive electrode active material according to claim 1 or 2, characterized in that: The average particle size of the positive electrode active material particles is P 50 , and satisfy 1μm≤P 50 ≤2.5μm, optionally, 1.3μm≤P 50 ≤2μm.

5. The positive electrode active material according to claim 4, characterized in that The volume distribution median particle size Dv of the positive electrode active material particles 50 Satisfy 2μm≤Dv 50 ≤4.5μm, optionally, 2.5μm≤Dv 50 ≤4μm.

6. The positive electrode active material according to claim 5, characterized in that 1≤Dv 50 / P 50 ≤2.5, optionally, 1.2≤Dv 50 / P 50 ≤2.

5.

7. The positive electrode active material according to claim 1 or 2, characterized in that: The compound shown in Formula Ι: Li 1±a (Ni x Co y Mn z G b )M c O₂ of formula I, where 0≤a≤0.1, 0≤b≤0.05, 0≤c≤0.05, 0.4≤x<1, 0<y<0.5, 0≤z<0.5, G includes at least one of Zr, Ti, Y, W, Al, Nb, and M includes at least one of La, Zr, B, Nb, Ti, W, Si, Mg, Al, Co.

8. The positive electrode active material according to claim 7, characterized in that 0＜b≤0.05。 9. The positive electrode active material according to claim 7, characterized in that The positive electrode active material includes a matrix and a coating material located on at least a part of the surface of the matrix, and the coating material includes the M element.

10. A method for preparing the positive electrode active material according to any one of claims 1 to 9, characterized in that: Comprising: Mixing a nickel-cobalt-manganese precursor and a lithium source to obtain a mixture; Heating the mixture to a first constant temperature section and keeping it warm. The temperature of the first constant temperature section is 600°C - 900°C. After the heat preservation ends, the temperature is raised to conduct the first sintering on the mixture. The temperature of the first sintering is 800°C - 1000°C. After the first sintering ends, the temperature is lowered to a second constant temperature section, and the temperature of the second constant temperature section is 300°C - 700°C and kept warm to obtain an intermediate product; Conducting a second sintering on the intermediate product, and the temperature of the second sintering is less than or equal to the temperature of the first sintering to obtain the positive electrode active material.

11. The method according to claim 10, characterized in that The method further includes: mixing the nickel-cobalt-manganese precursor, the lithium source, and an additive containing the G element to obtain a mixture.

12. The method according to claim 11, characterized in that When conducting the second sintering, mixing the intermediate product with a coating agent containing the M element.

13. The method according to claim 10, characterized in that The temperature of the second sintering is 300°C - 800°C.

14. The method according to claim 10, characterized in that The time of the first sintering and the second sintering are each independently 6h - 12h.

15. The method according to claim 11, characterized in that The additive includes at least one of an oxide containing the G element, a hydroxide containing the G element, and a carbonate containing the G element.

16. A positive electrode plate, characterized in that: Comprising the positive electrode active material according to any one of claims 1 - 9 or the positive electrode active material prepared by the method according to any one of claims 10 - 15.

17. A battery, characterized in that: Comprising the positive electrode sheet according to claim 16.

18. An electrical equipment, characterized in that: Comprising the battery according to claim 17.

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