Additive, method for preparing the same, positive electrode active material, positive electrode sheet, battery, and electric device

Abstract

This application provides additives and their preparation methods, positive electrode active materials, positive electrode sheets, batteries, and electrical devices. The additives include compounds represented by Formula I: La x’ Zr y’ M z’ O w’ Equation I, the grain size of the additive satisfies: where, Vn 10 Vn 50 Vn 90 The grain size V of the additive n The grain sizes corresponding to a cumulative volume percentage of 10%, 50%, and 90%, respectively. The additive proposed in this application has a small grain size. When mixed with the positive electrode active material as a coating material, the additive and the matrix material are mixed more uniformly. It can uniformly coat the surface of the matrix material, providing better protection for the structure of the positive electrode active material and improving the cycle stability of the positive electrode active material under high voltage.

Description

Technical Field

[0001] This application relates to the field of batteries, specifically to additives and their preparation methods, positive electrode active materials, positive electrode sheets, batteries, and electrical devices. Background Technology

[0002] Lithium-ion batteries, as a type of new energy product, have been widely used in new energy vehicles and consumer electronics. Their energy density directly determines the product's range. To better meet consumer demand, developing high-energy-density lithium-ion batteries is a crucial research direction. Among these, developing high-voltage cathode materials is an effective strategy. However, when operating under high-voltage conditions, cathode active materials face safety issues such as crystal structure destruction (e.g., lattice oxygen production), electrolyte decomposition leading to battery failure, and combustion / explosion.

[0003] To address the aforementioned issues, there is an urgent need to develop an additive to improve the cycle stability of positive electrode active materials under high voltage. Commercially available additives are typically micron-sized materials, which leads to uneven mixing with the matrix material when used as additives, hindering their effectiveness. Furthermore, commercially available additives are usually single-component materials, resulting in poor synergistic effects when different types of additives are physically mixed and used simultaneously. Summary of the Invention

[0004] This application aims to at least partially address one of the technical problems in the related art.

[0005] A first aspect of this application provides an additive comprising a compound represented by Formula I:

[0006] La x’ Zr y’ M z’ O w’ Formula I,

[0007] Where 0.3≤x'≤0.7, 0.3≤y'≤0.7, 0≤z'≤0.2, w'=1.6-2.0, and M includes one or more of Ba, Ca, Fe, B, Zn, Al, Ga, Ge, Mo, Ti, Mn, Mg, and Sn;

[0008] The grain size of the additive satisfies:

[0009] Among them, Vn 10 Vn 50 Vn 90 The grain size V of the additive n The grain sizes corresponding to the cumulative volume percentages of 10%, 50%, and 90%, respectively.

[0010] The additive proposed in this application has a small grain size. When mixed with the positive electrode active material as a coating material, the additive and the matrix material are mixed more uniformly, and the additive can uniformly coat the surface of the matrix material, providing better protection for the structure of the positive electrode active material. It can also improve the cycle stability of the positive electrode active material under high voltage. The additive proposed in this application also includes multiple metal elements, enabling multi-element coating of the positive electrode active material in one step, and improving the synergistic effect between the metal elements.

[0011] According to some embodiments of this application, Therefore, the additive has a small grain size, which can achieve uniform coating of the matrix material.

[0012] According to some embodiments of this application, Kn 90 =(Vn 90 -Vn 10 ) / Vn 50 0.5 < Kn 90 <3.5, optionally, 1 <Kn 90 <2.5. As a result, the grain size distribution of the additive is more uniform, which can improve the uniformity of mixing when mixed with the matrix material.

[0013] According to some embodiments of this application, the median particle size D of the additive is... 50 ≤0.5μm.

[0014] According to some embodiments of this application, the average particle size d of the additive 50 For 20nm≤d 50 ≤70nm, optionally, 30nm≤d 50 ≤60nm, d 50 This refers to the particle size that corresponds to when the cumulative distribution of the number of particles in the sample reaches 50%.

[0015] According to some embodiments of this application, the K of the additive 90 Satisfy: 0.35≤K 90 ≤0.8, optionally, 0.45≤K 90 ≤0.65, where K 90 =(d 90 -d 10 ) / d 50 d 10 d represents the particle size at which the cumulative distribution of the number of particles in the sample reaches 10%. 90 This refers to the particle size distribution that corresponds to a cumulative distribution of 90% in the sample. Therefore, a narrower particle size distribution results in a more uniform thickness of the additive material coating the surface of the positive electrode active material.

[0016] According to some embodiments of this application, the additive has a BET specific surface area of ​​20 m². 2 / g-40m 2 / g.

[0017] According to some embodiments of this application, the roundness of individual particles of the additive is Q1≥80%, and optionally, 85%≤Q1≤100%.

[0018] According to some embodiments of this application, the average roundness Q2 of the additive particles is ≥85%, and optionally, 90% ≤ Q2 ≤ 100%.

[0019] As a result, the better roundness allows the nanoparticles to be packed tightly together, resulting in a more uniform coating layer when used as a coating agent.

[0020] A second aspect of this application provides a method for preparing the additive provided in the first aspect of this application, the method comprising:

[0021] A La source, a Zr source, a M source, a precipitant, a complexing agent, and a solvent are mixed to obtain a mixture. The mixture is then co-precipitated to obtain a slurry. The co-precipitation temperature is 30℃-65℃. At least one of the La source, the Zr source, and the M source is a nitrate.

[0022] The slurry is aged, washed, dried, and crushed to obtain a precursor material, wherein the precursor material is a secondary particle formed from primary particle aggregation, and the precursor material includes a compound represented by Formula II:

[0023] La x Zr y M z (OH) w (NO3) u Formula II,

[0024] Wherein 0.3≤x≤0.7, 0.3≤y≤0.7, 0≤z≤0.2, 0.03≤u≤0.2, w=3.2-4.0, M includes one or more of Ba, Ca, Fe, B, Zn, Al, Ga, Ge, Mo, Ti, Mn, Mg, and Sn, and the number of particles with an average particle size less than or equal to 60nm in the precursor material accounts for 50%-80%;

[0025] The precursor material is sintered and crushed to obtain the additive, and the sintering temperature is 600℃-850℃.

[0026] The method provided in this application involves adding nitrates to the precursor material to dope it with a certain amount of nitrate ions. The nitrate ions lower the sintering temperature required for the precursor material, resulting in a more porous additive with lower hardness. During sintering, the primary particles shrink and the nitrate ions decompose to generate a certain amount of gas, causing the additive to agglomerate into loose, porous nano-sized primary particles. In summary, this application provides a simple process to obtain nano-sized additives. When used to coat the cathode active material matrix, this improves the uniformity of mixing with the matrix material, enhances the coating effect on the cathode active material, improves the structural stability of the cathode active material, and improves the cycle performance of the cathode active material under high pressure.

[0027] According to some embodiments of this application, the molar concentration of the complexing agent in the mixture is 0.05 mol / L to 0.5 mol / L.

[0028] According to some embodiments of this application, the complexing agent includes at least one of ammonia and ethylenediaminetetraacetic acid.

[0029] According to some embodiments of this application, the median particle size D of the precursor material 50 The particle size is 15μm-25μm, optionally 17μm-22μm, and further optionally 18μm-20μm. Therefore, due to the low hardness of the precursor material, even if the median particle size of the precursor material is large, it can be broken down into nanoscale additives through a crushing process, reducing the complexity of the process.

[0030] According to some embodiments of this application, the maximum particle size D of the precursor material is... max The particle size is 90μm-150μm, optionally 110μm-130μm, and further optionally 115μm-120μm. Therefore, the precursor particle size is relatively moderate, ensuring the uniformity of sintering in the sintering process.

[0031] According to some embodiments of this application, at least one of the following conditions is met:

[0032] The loose bulk density (AD) of the precursor material is 0.4 g / cm³. 3 -0.9g / cm 3 0.55g / cm³ is an optional value. 3 -0.75g / cm 3 ;

[0033] The tap density TD of the precursor material is 1 g / cm³. 3 -1.4g / cm 3 The option is 1.15g / cm³. 3 -1.25g / cm 3 ;

[0034] The precursor material has a BET specific surface area of ​​100 m². 2 / g-170m 2 / g, 115m can be selected. 2 / g-130m 2 / g.

[0035] Therefore, ensuring a high capacity of sintering bowls is beneficial for increasing output and is suitable for industrial production.

[0036] A third aspect of this application provides a positive electrode active material, comprising: a matrix; and a coating material located on at least a portion of the surface of the matrix, the coating material comprising the additives provided in the first aspect of this application or additives prepared by the method provided in the second aspect of this application. Thus, the positive electrode active material exhibits good structural stability and cycle performance.

[0037] The fourth aspect of this application provides a positive electrode sheet, including the positive electrode active material provided in the third aspect of this application.

[0038] The fifth aspect of this application provides a battery including the positive electrode provided in the fourth aspect of this application.

[0039] The sixth aspect of this application provides an electrical device, including the battery provided in the fifth aspect of this application. Attached Figure Description

[0040] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0041] Figure 1 A schematic flowchart of a method for preparing an additive according to an embodiment of this application is shown.

[0042] Figure 2 The image shows a scanning electron microscope (SEM) image of the precursor material prepared in Example 1 at 30K magnification.

[0043] Figure 3 The XRD pattern of the precursor material prepared in Example 1 is shown.

[0044] Figure 4 The XRD pattern of the additive prepared in Example 1 is shown.

[0045] Figure 5 A scanning electron microscope image of the additive prepared in Example 1 is shown.

[0046] Figure 6 A schematic diagram of particle size measurement using Nano Measurer software is shown.

[0047] Figure 7 Showing Figure 6 Particle size distribution diagram after measurement. Detailed Implementation

[0048] The embodiments of this application are described in detail below. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0049] A first aspect of this application provides an additive comprising a compound represented by Formula I:

[0050] La x’ Zr y’ M z’ O w’ Formula I,

[0051] Where 0.3≤x'≤0.7, 0.3≤y'≤0.7, 0≤z'≤0.2, w'=1.6-2.0, and M includes one or more of Ba, Ca, Fe, B, Zn, Al, Ga, Ge, Mo, Ti, Mn, Mg, and Sn;

[0052] The grain size of the additive satisfies:

[0053] Among them, Vn 10 Vn 50 Vn 90 The grain size V of the additive n Grain sizes corresponding to cumulative volume percentages of 10%, 50%, and 90%, respectively.

[0054] The additive proposed in this application has a small crystal size. When used as a coating material and mixed with the positive electrode active material, the additive and the matrix material are mixed more evenly, which provides better protection for the structure of the positive electrode active material and can improve the cycle stability of the positive electrode active material under high voltage.

[0055] The additive proposed in this application, when coated on the surface of the positive electrode active material, can reduce the phase transition of the positive electrode active material under high voltage, reduce side reactions between the positive electrode active material and the electrolyte, and improve the cycle performance of the battery. Specifically, La 3 + It can stabilize the layered structure of the positive electrode active material under high voltage, reduce the oxidizability of the positive electrode active material surface, prevent the transformation to spinel or rock salt structure, and reduce electrolyte decomposition; Zr 4+A stable oxide layer can be formed, reducing the occurrence of phase transitions. Selecting a suitable M element can further reinforce the process. The additive proposed in this application includes multiple metal elements, enabling one-step coating of the positive electrode active material with multiple elements and enhancing the synergistic effect between the metal elements.

[0056] In this application, Vn 10 Vn 50 Vn 90 The test was conducted using a Rigaku Smartlab 9KW rotating target diffractometer, with a range of 10-80°, a voltage of 40kV, a current of 200mA, a step size of 0.02°, and a scan time of 2° / min. The test results were obtained by statistically calculating the microcrystal size using the WPPF grain size distribution function in SmartLab Studio II software according to the Fundamental Parameter method (FP method).

[0057] As an example, Vn 10 It can be etc., or a range consisting of any of the above values.

[0058] As an example, Vn 50 It can be etc., or a range consisting of any of the above values.

[0059] As an example, Vn 90 It can be etc., or a range consisting of any of the above values.

[0060] According to some specific embodiments of this application

[0061] According to some embodiments of this application, Kn 90 =(Vn 90 -Vn 10 ) / Vn 50 0.5 < Kn 90 <3.5, for example, it can be 0.6, 1, 1.5, 2, 2.5, 3, 3.4, etc., or it can be a range of any of the above values. When Vn 10 Vn 50 Vn 90 Within the scope defined in this application, by making the Kn of the additive... 90 Within the scope defined in this application, the additive has a small grain size and a more uniform distribution. When mixed with the matrix material, it can further improve the uniformity, so that the additive is uniformly coated on the surface of the matrix material, thereby improving the structural stability of the matrix material and its cycle performance.

[0062] According to some specific embodiments of this application, 1 < Kn 90 <2.5.

[0063] According to some embodiments of this application, the median particle size D of the additive is... 50 ≤0.5μm, D 50 This refers to the particle size that corresponds to when the cumulative distribution of the number of particles in the sample reaches 50%.

[0064] In this application, the volume average particle size of the additive can be tested using a Malvern laser particle size analyzer Mastersizer 3000.

[0065] As an example, the median particle size D of the additive 50 It can be 0.4μm, 0.3μm, 0.2μm, 0.1μm, 0.05μm, 0.04μm, 0.01μm, etc., or it can be a range of any of the above values.

[0066] According to some specific embodiments of this application, the average particle size d of the additive 50 It can be 20nm-70nm, d 50 This refers to the particle size that corresponds to a cumulative distribution of 50% of the sample. For example, it can be 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, or any range of the above values.

[0067] According to some specific embodiments of this application, the average particle size d of the additive 50 It can be 30nm-60nm.

[0068] Therefore, the additive has a smaller crystal size and particle size, and when mixed with the matrix material, the mixture is more uniform, resulting in a better coating effect on the matrix and improving the structural stability of the positive electrode active material.

[0069] According to some embodiments of this application, the K of the additive 90 Satisfy: 0.35≤K 90 ≤0.8, where K 90 =(d 90 -d 10 ) / d 50 d 10 d represents the particle size at which the cumulative distribution of the number of particles in the sample reaches 10%. 90 This refers to the particle size distribution that corresponds to a cumulative distribution of 90% of the sample. Therefore, a narrower particle size distribution results in a more uniform thickness when the additive material is coated on the surface of the cathode material.

[0070] In this application, d 10 d 50 d90 It can be measured using a Nano Measurer by selecting 100 relatively independent particles, and then taking the average value.

[0071] As an example, K 90 It can be 0.35, 0.45, 0.55, 0.65, 0.75, 0.8, etc., or it can be a range of any of the above values.

[0072] According to some embodiments of this application, 0.45≤K 90 ≤0.65.

[0073] According to some embodiments of this application, the BET specific surface area of ​​the additive can be 20 m². 2 / g-40m 2 / g.

[0074] In this application, the BET specific surface area of ​​the additive can be obtained by testing a Tristar II 3020 specific surface area analyzer from Micromertics, USA.

[0075] As an example, the BET specific surface area of ​​the additive can be 20 m². 2 / g、25m 2 / g、30m 2 / g、35m 2 / g、40m 2 / g, etc., or a range consisting of any of the above values.

[0076] The BET specific surface area of ​​the additive is within the above range, which enables the nano-additive particles to uniformly and densely cover the surface of the positive electrode active material, reducing the direct contact between the positive electrode active material and the electrolyte, suppressing side reactions, and binding more tightly to the positive electrode active material. During the charging and discharging process, when the volume of the positive electrode active material changes, the additive coating on the surface is not easy to fall off, which can extend the cycle life of the battery.

[0077] According to some embodiments of this application, the roundness Q1 of individual particles of the additive is ≥80%.

[0078] In this application, the particle roundness Q = particle's long axis / particle's short axis × 100%, where the particle's long axis is the length of the particle's longest diagonal, and the particle's short axis is the size of the particle's shortest diagonal. The sizes of the longest and shortest diagonals can be tested using a scanning electron microscope (SEM).

[0079] As an example, the roundness Q1 of a single particle can be 80%, 85%, 90%, 95%, 100%, etc., or can be a range of any of the above values.

[0080] According to some specific embodiments of this application, 85% ≤ Q1 ≤ 100%.

[0081] According to some embodiments of this application, the average roundness Q2 of the additive particles is ≥85%.

[0082] Therefore, by keeping Q1 and Q2 within the above range, the better roundness allows the nanoparticles to be tightly packed together, resulting in a more uniform coating layer when used as a coating agent.

[0083] In this application, when measuring the average roundness of the additive particles, at least 400 particles are randomly selected. After obtaining the roundness of a single particle by measuring its major and minor axes, the average roundness of the 400 particles is taken as the average roundness of the particles.

[0084] As an example, the average roundness Q2 of the additive particles can be 85%, 90%, 95%, 100%, etc., or can be a range of any of the above values.

[0085] According to some specific embodiments of this application, 90% ≤ Q2 ≤ 100%.

[0086] A second aspect of this application provides a method for preparing the additive provided in the first aspect of this application, the method comprising:

[0087] A La source, a Zr source, a M source, a precipitant, a complexing agent, and a solvent are mixed to obtain a mixture. The mixture is then co-precipitated to obtain a slurry. The co-precipitation temperature is 30℃-65℃. At least one of the La source, the Zr source, and the M source is a nitrate.

[0088] The slurry is aged, washed, dried, and crushed to obtain a precursor material, wherein the precursor material is a secondary particle formed from primary particle aggregation, and the precursor material includes a compound represented by Formula II:

[0089] La x Zr y M z (OH) w (NO3) u Formula II,

[0090] Wherein 0.3≤x≤0.7, 0.3≤y≤0.7, 0≤z≤0.2, 0.03≤u≤0.2, w=3.2-4.0, M includes one or more of Ba, Ca, Fe, B, Zn, Al, Ga, Ge, Mo, Ti, Mn, Mg, and Sn, and the number of particles with an average particle size less than or equal to 60nm in the precursor material accounts for 50%-80%;

[0091] The precursor material is sintered and crushed to obtain the additive, and the sintering temperature is 600℃-850℃.

[0092] The method provided in this application involves adding nitrates to the precursor material to dope it with a certain amount of nitrate ions. The nitrate ions lower the sintering temperature required for the precursor material, resulting in a more porous additive with lower hardness. The precursor material is composed of nano-sized primary particle agglomerations. During sintering, the primary particles shrink and the nitrate ions decompose to generate a certain amount of gas, resulting in the additive being composed of loose, porous nano-sized primary particle agglomerations. In summary, this application provides a simple process to obtain nano-sized additives. When used to coat the positive electrode active material matrix, this improves the uniformity of mixing with the matrix material, enhances the coating effect on the positive electrode active material, improves the structural stability of the positive electrode active material, and improves the cycle performance of the positive electrode active material.

[0093] The method provided in this application is described in detail below. (Refer to...) Figure 1 The method includes:

[0094] S10: Mix the La source, Zr source, M source, precipitant, complexing agent, and solvent to obtain a mixture, and then co-precipitate the mixture to obtain a slurry.

[0095] In this step, La source, Zr source, M source, and solvent are mixed to obtain solution A. At least one of the La source, Zr source, and M source is a nitrate. A certain concentration of precipitant aqueous solution B and complexing agent aqueous solution C are prepared. A certain amount of pure water is added to the reaction vessel. Solutions B and C are used as the reaction base liquid. The temperature is raised to the required reaction temperature. The mixed solution A, precipitant aqueous solution B, and complexing agent aqueous solution C are added to the reaction vessel at a certain flow rate through a metering pump to carry out a co-precipitation reaction to obtain a slurry.

[0096] By controlling the amount of nitrate added, the nitrate content in the precursor material can be controlled, and the sintering temperature can be reduced during the sintering of the precursor material, resulting in a more loosely packed additive with lower hardness.

[0097] According to some embodiments of this application, at least one of the La source, the Zr source, and the M source is a nitrate, and the others can be one or more of sulfates and chlorides containing the above-mentioned metal elements.

[0098] According to some embodiments of this application, the concentration of the metal salt solution can be 0.5 mol / L to 3 mol / L, for example, it can be 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, etc., or it can be any range of the above values.

[0099] According to some specific embodiments of this application, the concentration of the metal salt solution can be 0.8 mol / L to 2 mol / L.

[0100] According to some embodiments of this application, the precipitant includes one or more of NaOH, KOH, and LiOH.

[0101] According to some embodiments of this application, the concentration of the precipitant aqueous solution can be 5 mol / L-12 mol / L, for example, it can be 5 mol / L, 7 mol / L, 9 mol / L, 11 mol / L, 12 mol / L, etc., or it can be any range of the above values.

[0102] According to some embodiments of this application, the concentration of the precipitant aqueous solution can be 7 mol / L-10 mol / L.

[0103] According to some embodiments of this application, the complexing agent includes one or more of ammonia and ethylenediaminetetraacetic acid.

[0104] According to some embodiments of this application, the molar concentration of the complexing agent in the mixture is 0.05 mol / L-0.5 mol / L, for example, it can be 0.05 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, etc., or it can be any range of the above values.

[0105] By keeping the content of the complexing agent within the above range,

[0106] According to some embodiments of this application, the pH value of the reaction substrate is 9.5-11.5.

[0107] According to some embodiments of this application, the reaction temperature for coprecipitation is 30℃-65℃, and the stirring speed is 300rpm-800rpm.

[0108] As an example, the reaction temperature for coprecipitation can be 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, etc., or a range of any of the above values.

[0109] As an example, the stirring speed can be 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, etc., or a range of any of the above values.

[0110] S20: The slurry is aged, washed, dried, and crushed to obtain precursor materials.

[0111] In this step, the washing method is rinsing or alternating rinsing and starching. The washing water temperature is 15℃-80℃, the starching speed is 300rpm-700rpm, and the starching time is 0.3h-2h.

[0112] In this application, the nitrate content in the precursor material can be controlled by controlling the washing intensity of the washing process.

[0113] According to some embodiments of this application, drying can be carried out by a forced-air drying oven at a temperature of 100℃-180℃ for a time of 3h-24h.

[0114] According to some embodiments of this application, the equipment and parameters used for crushing are not particularly limited, as long as they can process the dried material to the required particle size. The drying equipment can be a soybean milk maker, roller mill, colloid mill, mechanical mill, air jet mill, etc.

[0115] According to some embodiments of this application, the median particle size D of the precursor material 50 It can be 15μm-25μm, for example, it can be 15μm, 17μm, 19μm, 21μm, 23μm, 25μm, etc., or it can be a range of the above values.

[0116] According to some specific embodiments of this application, the median particle size D of the precursor material 50 It can be 17μm-22μm.

[0117] According to some specific embodiments of this application, the median particle size D of the precursor material 50 It can be 18μm-20μm.

[0118] According to some embodiments of this application, the maximum particle size D of the precursor material is... max The value is 90μm-150μm, for example, it can be 90μm, 110μm, 130μm, 150μm, etc., or it can be a range of the above values.

[0119] According to some specific embodiments of this application, the maximum particle size D of the precursor material is... max It can be 110μm-130μm.

[0120] According to some specific embodiments of this application, the maximum particle size D of the precursor material is... max It can be 115μm-120μm.

[0121] Therefore, the precursor material has a relatively small overall particle size, which is beneficial for preparing nanoscale additives.

[0122] In this application, the precursor material D 50 Dmax The particle size can be obtained using a Malvern Mastersizer 3000 laser particle size analyzer.

[0123] According to some embodiments of this application, the loose packing density AD of the precursor material can be 0.4 g / cm³. 3 -0.9g / cm 3 For example, it can be 0.4 g / cm³. 3 0.5g / cm 3 0.6g / cm 3 0.7g / cm 3 0.8g / cm 3 0.9g / cm 3 etc., or a range consisting of the above values.

[0124] According to some embodiments of this application, the loose packing density (AD) of the precursor material can be 0.55 g / cm³. 3 -0.75g / cm 3 .

[0125] In this application, the bulk density of the precursor material can be measured using an FS4-2 bulk density meter.

[0126] According to some embodiments of this application, the tap density TD of the precursor material can be 1 g / cm³. 3 -1.4g / cm 3 For example, it could be 1g / cm³ 3 1.2g / cm 3 1.3g / cm 3 1.4g / cm 3 etc., or a range consisting of the above values.

[0127] According to some embodiments of this application, the tap density (TD) of the precursor material can be 1.15 g / cm³. 3 -1.25g / cm 3 .

[0128] In this application, the tap density of the precursor material can be obtained by testing with a BT-30 tap density tester from Baxter Corporation.

[0129] According to some embodiments of this application, the BET specific surface area of ​​the precursor material is 100 m². 2 / g-170m 2 / g, for example, can be 100m 2 / g、120m 2 / g, 140m 2 / g、155m 2 / g、170m2 / g, etc., or a range consisting of the above values.

[0130] According to some embodiments of this application, the BET specific surface area of ​​the precursor material is 115 m². 2 / g-130m 2 / g.

[0131] In this application, the BET specific surface area of ​​the precursor material can be obtained by testing the specific surface area using a Tristar II 3020 surface area analyzer from Micromertics, Inc.

[0132] The loose packing density, tapped density, and BET specific surface area of ​​the precursor material in this application are within the above-mentioned range, which can ensure a high packing volume in the sintering process, which is conducive to increasing output and is suitable for industrial production.

[0133] S30: The precursor material is sintered and crushed to obtain the additive, wherein the sintering temperature is 600℃-850℃.

[0134] According to some embodiments of this application, the precursor material is sintered and crushed to obtain the additive. The sintering temperature is 600℃-850℃ and the holding time is 2h-15h.

[0135] As an example, the sintering time can be 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, etc., or a range of any of the above values.

[0136] As an example, the heat preservation time can be 2h, 5h, 8h, 11h, 14h, 15h, etc., or it can be any range of the above values.

[0137] According to some specific embodiments of this application, the sintering temperature is 680℃-750℃, and the holding time can be 3h-10h.

[0138] This application obtains additives with small grain size and particle size by controlling the nitrate content in the precursor material and sintering at a lower temperature. When the additive is mixed with the matrix material, it is mixed more uniformly, which can uniformly coat the surface of the matrix material, thereby improving the structural stability of the matrix material and improving the cycle performance of the material.

[0139] As an example, sintered materials can be nanoscaled using an air jet mill.

[0140] In summary, the additive and its preparation method proposed in this application have the following advantages:

[0141] (1) The additive has a smaller grain size and particle size, which allows it to mix more evenly with the matrix material. It can uniformly coat the surface of the matrix material, improve the structural stability of the matrix material, and improve the cycling performance of the material under high voltage.

[0142] (2) The additive has a more uniform grain size distribution and particle size distribution. When mixed with the matrix material, it can further improve the uniformity of mixing, so that the matrix material surface is uniformly coated with the additive, improve the overall performance of the matrix, and reduce the performance decline that may be caused by poor local coating.

[0143] (3) During the preparation of additives, metal elements are made to achieve uniform co-precipitation at the atomic level through co-precipitation, so that the additive materials can play a greater synergistic role.

[0144] (4) The precursor material is formed by soft agglomeration of nano-sized primary particles and has a certain amount of nitrate doping, which is beneficial to lowering the sintering temperature and making the sintering material soft and loose, which is beneficial to the subsequent nano-sizing process, so that the nano-sizing process can obtain additives with a particle size of nano-scale without complicated processes.

[0145] A third aspect of this application provides a positive electrode active material, comprising a matrix and a coating material located on at least a portion of the surface of the matrix, the coating material comprising an additive provided in the first aspect of this application or an additive prepared by a method provided in the second aspect of this application.

[0146] According to some embodiments of this application, when coating the matrix, the coating amount of metal elements in the additive can be 500ppm-5000ppm, for example, it can be 500ppm, 1000ppm, 2000ppm, 3000ppm, 4000ppm, 5000ppm, etc., or it can be any range of the above values.

[0147] According to some specific embodiments of this application, the coating amount of metal elements in the additive can be 1000ppm-3000ppm.

[0148] As an example, the substrate material may include lithium-ion battery cathode active materials. For example, it includes, but is not limited to, lithium cobalt oxide, high-nickel ternary cathode active materials, and lithium-rich manganese-based cathode active materials.

[0149] By coating at least a portion of the surface of the matrix material with the additives proposed in this application, the structural stability of the matrix material can be improved, and the high-pressure cycling performance of the material can be enhanced.

[0150] The fourth aspect of this application provides a positive electrode sheet, including the positive electrode active material provided in the third aspect of this application.

[0151] Typically, the positive electrode sheet may include a positive current collector and a positive active material layer disposed on at least one side of the positive current collector. The positive active material layer may include the aforementioned positive active material. The positive current collector may include, but is not limited to, metal foils (such as aluminum foil and copper foil) or composite current collectors. The positive active material layer may also include binders and conductive agents. The specific types and sources of binders and conductive agents are not particularly limited, and those skilled in the art can flexibly select them according to actual needs. For example, binders may include, but are not limited to, polyvinylidene fluoride (PVDF) and polyvinylidene fluoride (PVDF), and conductive agents may include, but are not limited to, one or more of conductive carbon black, carbon nanotubes, and graphene.

[0152] The fifth aspect of this application provides a battery including the positive electrode provided in the fourth aspect of this application.

[0153] Typically, in addition to the positive electrode, a battery may also include a negative electrode, an electrolyte, and a separator. The specific structure or composition of the negative electrode, electrolyte, and separator is not particularly limited, and those skilled in the art can choose flexibly according to actual needs.

[0154] For example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material layer disposed on at least one side of the negative electrode current collector. The negative electrode active material layer may include a negative electrode active material, a binder, a conductive agent, etc. The negative electrode current collector may include, but is not limited to, metal foil (such as copper foil) or composite current collectors. The specific types and sources of the active material, binder, and conductive agent in the negative electrode sheet are not particularly limited, and those skilled in the art can flexibly select them according to actual needs. For example, the negative electrode active material may include, but is not limited to, one or more of hard carbon, soft carbon, silicon-based materials, and silicon-carbon materials; the binder may include, but is not limited to, styrene-butadiene rubber; and the conductive agent may include, but is not limited to, one or more of conductive carbon black, carbon nanotubes, and graphene. Furthermore, conventional components such as thickeners may be selectively added to the negative electrode active material layer.

[0155] The diaphragm can include, but is not limited to, polyethylene (PE) membrane, polypropylene (PP) membrane, PP / PE / PP composite membrane, composite ceramic diaphragm, and coated diaphragm.

[0156] The electrolyte may include organic solvents and electrolyte salts. Taking lithium batteries as an example, the organic solvents may include one or more ester solvents such as dimethyl carbonate (DMC), ethylene carbonate (EC), and ethyl methyl carbonate (EMC). The electrolyte salts may include one or more common lithium salts such as lithium hexafluorophosphate (LiPF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), lithium bis(oxalato)borate (LiBOB), and lithium difluorophosphate (LiO2F2). Optionally, additives may also be added to the electrolyte, including but not limited to common additives such as vinylene carbonate (VC) and fluoroethylene carbonate (FEC).

[0157] The sixth aspect of this application provides an electrical device, including the battery provided in the fifth aspect of this application.

[0158] The specific types of electrical equipment are not particularly limited, and those skilled in the art can choose flexibly according to actual needs, such as including but not limited to electronic equipment, household appliances, vehicles and vertical take-off and landing aircraft.

[0159] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the invention in any way. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0160] In the following examples, all raw materials are commercially available unless otherwise specified.

[0161] Example 1

[0162] According to the molar ratio La:Zr:Al=0.5:0.45:0.05, lanthanum nitrate, zirconium oxychloride, and aluminum nitrate raw materials were weighed to prepare a metal salt solution with a concentration of 2 mol / L. An 8 mol / L sodium hydroxide solution was prepared as a precipitant, and a 9 mol / L ammonia solution was prepared as a complexing agent.

[0163] Pure water (20% of the reactor volume), a certain amount of precipitant and complexing agent were added to the reactor to achieve an ammonia content of 0.2 mol / L and a pH of 10.5 in the bottom solution. The reactor temperature was raised to 60°C, and the stirring speed was 600 rpm. A metal salt solution, sodium hydroxide precipitant solution, and ammonia complexing agent solution were added concurrently to the reactor for co-precipitation to obtain a slurry.

[0164] The slurry is filtered to obtain a filter cake, which is then washed. The washing process includes: first step: rinsing once with pure water at 70°C and an equal volume of slurry; second step: rinsing once with water at 40°C; third step: rinsing once with water at 70°C and an equal volume of slurry at the same temperature as in the first step, and then filtering to obtain a filter cake.

[0165] The filter cake was placed in a forced-air drying oven and dried at 120℃ for 12 hours to obtain the precursor material. The morphology of the precursor material is as follows: Figure 2 As shown, the XRD test results of the precursor material are attached. Figure 3 Its chemical formula is La 0.5 Zr 0.45 Al 0.05 (OH) 3.35 (NO3) 0.1 .

[0166] The obtained precursor material was sintered at 700℃ for 8 hours to obtain a sintered material. The sintered material was then crushed using an air jet mill to obtain nano-additive materials. The XRD pattern of the additives is shown in the figure. Figure 4 As shown, the morphology of the additive is as follows Figure 5 As shown, its chemical formula is La. 0.5 Zr 0.45 Al 0.05 O 1.725 The crystal phase of this nano-additive material is La2Zr2O7 (PDF71-2363).

[0167] refer to Figure 6 The particle size distribution of the additives was measured using Nanomeasure software, and the results are shown in the figure below. Figure 7 As shown.

[0168] Uncoated lithium cobalt oxide material was used as the matrix, and the metal element coating amount of 1000ppm was mixed with nano-additives. The mixture was sintered at 900℃ to obtain coated lithium cobalt oxide material. The material was then made into a coin cell, and its cycle performance was investigated.

[0169] The preparation methods of the additives in Examples 2-10 and Comparative Examples 1-3 are the same as those in Example 1. The differences and test results are detailed in Tables 1 and 2.

[0170] Performance testing:

[0171] 1. Particle size test: The particle size was obtained using a Malvern Mastersizer 3000 laser particle size analyzer.

[0172] 2. Morphological testing: The results were obtained using a Hitachi S-4800 scanning electron microscope from Japan.

[0173] 3. Specific surface area: Measured using a Tristar II 3020 specific surface area analyzer from Micromertics, USA.

[0174] 4. Loose packing density: Measured using a loose packing density meter of model FS4-2.

[0175] 5. Tap density: Measured using a BT-30 tap density tester from Baxter Corporation.

[0176] 6.Vn 10 Vn 50 Vn 90 The measurements were performed using a Rigaku Smartlab 9KW rotating target diffractometer, with a range of 10-80°, a voltage of 40kV, a current of 200mA, a step size of 0.02°, and a scan time of 2° / min. The test results were obtained by statistically calculating the microcrystal size using the WPPF grain size distribution function in SmartLab Studio II software according to the Fundamental Parameter method (FP method).

[0177] Assembly of button cells:

[0178] First, a mixture of non-aqueous electrolyte secondary battery positive electrode active material, acetylene black, and polyvinylidene fluoride (PVDF) in a mass ratio of 95:2.5:2.5 is coated onto aluminum foil and dried. The mixture is then stamped into a positive electrode sheet with a diameter of 12 mm and a thickness of 120 μm using a pressure of 100 MPa. Finally, the positive electrode sheet is placed in a vacuum drying oven and dried at 120°C for 12 hours.

[0179] The negative electrode uses a Li metal sheet with a diameter of 17 mm and a thickness of 1 mm; the separator uses a polyethylene porous membrane with a thickness of 25 μm; the electrolyte uses an equal volume mixture of 1 mol / L LiPF6, ethylene carbonate (EC) and diethyl carbonate (DEC).

[0180] The positive electrode, separator, negative electrode, and electrolyte were assembled into a 2025 coin cell in an Ar gas glove box with a water content and oxygen content of less than 5 ppm. The cell at this stage was considered an unactivated cell.

[0181] After fabricating the button cell, let it stand for 24 hours. Once the open-circuit voltage stabilizes, charge it at a current density of 20 mA / g to the cutoff voltage of 4.55V, and then charge it at a constant voltage of 4.55V until the cutoff current is 0.024 mA. Then discharge it at the same current density to the cutoff voltage of 3.0V, and repeat the above process once more. The resulting cell is considered the activated cell.

[0182] 7. Battery cycle performance

[0183] The battery was activated by charging and discharging twice at a current density of 20 mA / g, with a cutoff voltage of 3.0-4.5V. Using the activated battery sample, a specified number of charge-discharge cycles (e.g., 50 cycles) were performed at 45°C with a current density of 1C within a voltage range of 3.0-4.45V. As described above, the discharge specific capacity for each charge-discharge cycle was obtained by using the current density and the discharge time of each cycle. The cycle performance of the battery was characterized by high-temperature capacity retention, where high-temperature capacity retention = discharge specific capacity at the specified number of cycles / initial discharge specific capacity * 100%.

[0184]

[0185]

[0186]

[0187] As can be seen from Tables 1 and 2, the additive proposed in this application can control the grain size of the additive during the preparation process by controlling the co-precipitation temperature, the nitrate content in the precursor, and the sintering temperature. By keeping the grain size within the range defined in this application, the uniformity of mixing can be improved when it is mixed with the matrix material, so that the additive is uniformly coated on the surface of the matrix material, which has a better protective effect on the positive electrode active material, thereby improving the cycle performance of the battery.

[0188] As can be seen from Examples 1 and 2, when the types of M elements in the additives are different, by controlling the co-precipitation temperature, the nitrate content in the precursor, and the sintering temperature, additives with grain sizes within the range defined in this application can be obtained, thereby obtaining batteries with better cycle performance. This shows that as long as the grain size is controlled within the range to be protected in this application, additives with different metal elements can be obtained, thereby improving the uniformity of mixing the additives with the matrix material, improving the coating effect on the matrix material, and improving the stability of the matrix material.

[0189] As can be seen from the comparison between Example 1 and Example 3, the grain size Vn of the additive can be adjusted by changing the co-precipitation temperature and the molar concentration of ammonia during the preparation of the additive. 10 Vn 50 and Vn 90 And so on, thereby adjusting the Kn of the additives. 90 By making Kn 90 Within the preferred scope of this application, the uniformity of additive grain size distribution can be improved, and when mixed with the matrix material, the coating effect on the matrix material can be improved, further enhancing the cycle performance of the battery.

[0190] As can be seen from Example 4 compared to Example 1, the d of the additive can be adjusted by changing the co-precipitation temperature and the molar concentration of ammonia. 50 The more ammonia water used, the stronger the complexing ability, the smaller the primary crystal size of the additive, and the higher the d of the final additive. 50 The smaller, by making d 50 Within the preferred scope of this application, the grain size of the additive can be reduced, the coating effect of the additive on the matrix material can be improved, the stability of the matrix material under high voltage can be improved, and the cycle performance of the battery can be improved.

[0191] As can be seen from Examples 1, 5, 6, Comparative Example 1, and Comparative Example 2, the nitrate content in the precursor can be adjusted by changing the washing method. At the same sintering temperature, the higher the nitrate content, the looser the final additive becomes, and the lower its hardness. Then, through simple crushing, nano-additives can be obtained. The uniform mixing of nano-additives with the matrix material improves the coating effect on the matrix material, enhances the stability of the matrix material under high voltage, and improves the cycle performance of the battery. If the nitrate content in the precursor material is too low, the improvement effect on the precursor material and the additive is not significant; if the nitrate content in the precursor material is too high, it will melt during sintering, and the small primary particle size of the precursor material makes it prone to agglomeration, resulting in an increase in the final additive grain size.

[0192] As can be seen from Examples 1 and 7, the additive proposed in this application can uniformly coat different positive electrode active materials, thereby improving the stability of the positive electrode active materials under high voltage and improving the cycle performance of the battery.

[0193] As can be seen from Examples 1 and 8, when the metal elements coated on the substrate surface are within the preferred range defined in this application, the stability of the positive electrode active material is better, and the cycle performance of the battery is superior. If the content of the coated metal elements is further increased, the thickness of the coating layer increases. During battery cycling, the positive electrode active material will undergo lattice expansion and contraction. The thicker coating layer will increase mechanical stress to a certain extent, affecting the structural stability of the positive electrode active material.

[0194] As can be seen from Comparative Example 3, if the sintering temperature is too high during the preparation of the additive, the grain size and density of the prepared additive will be affected. 50 d 50 The relatively large particle size will reduce the uniformity of the mixture when mixed with the substrate, affecting the coating effect on the substrate and ultimately reducing the cycle performance of the battery.

[0195] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0196] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. An additive, characterized in that, Including compounds represented by Formula I: La x’ Zr y’ M z’ O w’ Formula Ι Where 0.3≤x'≤0.7, 0.3≤y'≤0.7, 0≤z'≤0.2, w'=1.6-2.0, and M includes one or more of Ba, Ca, Fe, B, Zn, Al, Ga, Ge, Mo, Ti, Mn, Mg, and Sn; The grain size of the additive satisfies: 0 < Vn 10 <200Å, 160Å <Vn 50 <500Å, 300Å <Vn 90 <800Å, where Vn 10 Vn 50 Vn 90 The grain size V of the additive n The grain sizes corresponding to a cumulative volume percentage of 10%, 50%, and 90%, respectively; Kn 90 =(Vn 90 - Vn 10 ) / Vn 50 ,0.5<Kn 90 <3.5; The average particle size d of the additive 50 For 20nm≤d 50 ≤70nm, d 50 This refers to the particle size that corresponds to when the cumulative distribution of the number of particles in the sample reaches 50%.

2. The additive according to claim 1, characterized in that, 50Å<Vn 10 <200Å,170Å<Vn 50 <350Å,400Å<Vn 90 <650Å。 3. The additive according to claim 1 or 2, characterized in that, 1<Kn 90 <2.5。 4. The additive according to claim 3, characterized in that, The median particle size D of the additive 50 ≤0.5μm.

5. The additive according to claim 1, characterized in that, The average particle size d of the additive 50 For 30nm≤d 50 ≤60nm.

6. The additive according to claim 5, characterized in that, The additive K 90 Satisfy: 0.35≤K 90 ≤0.

8.

7. The additive according to claim 6, characterized in that, The additive K 90 Satisfies: 0.45≤K 90 ≤0.65, where K 90 =(d 90 -d 10 ) / d 50 d 10 d represents the particle size at which the cumulative distribution of particles in the sample reaches 10%. 90 This refers to the particle size that corresponds to when the cumulative distribution of the number of particles in the sample reaches 90%.

8. The additive according to claim 6, characterized in that, The additive has a BET specific surface area of ​​20 m². 2 / g-40m 2 / g.

9. The additive according to claim 8, characterized in that, The roundness of individual particles of the additive is Q1≥80%.

10. The additive according to claim 9, characterized in that, The roundness Q1 of a single particle of the additive satisfies: 85% ≤ Q1 ≤ 100%.

11. The additive according to claim 9, characterized in that, The average roundness Q2 of the additive particles is ≥85%.

12. The additive according to claim 11, characterized in that, The average roundness Q2 of the additive particles satisfies: 90% ≤ Q2 ≤ 100%.

13. A method for preparing the additive according to any one of claims 1-12, characterized in that, include: A La source, a Zr source, a M source, a precipitant, a complexing agent, and a solvent are mixed to obtain a mixture. The mixture is then co-precipitated to obtain a slurry. The co-precipitation temperature is 30℃-65℃. At least one of the La source, the Zr source, and the M source is a nitrate. The slurry is aged, washed, dried, and crushed to obtain a precursor material, wherein the precursor material is a secondary particle formed from primary particle aggregation, and the precursor material includes a compound represented by Formula II: La x Zr y M z (OH) w (NO3) u Formula II Wherein 0.3≤x≤0.7, 0.3≤y≤0.7, 0≤z≤0.2, 0.03≤u≤0.2, w=3.2-4.0, M includes one or more of Ba, Ca, Fe, B, Zn, Al, Ga, Ge, Mo, Ti, Mn, Mg, and Sn, and the proportion of particles with an average particle size less than or equal to 60 nm in the precursor material is 50%-80%; The precursor material is sintered and crushed to obtain the additive, wherein the sintering temperature is 600℃-850℃. The molar concentration of the complexing agent in the mixture is 0.05 mol / L to 0.5 mol / L; The median particle size D of the precursor material 50 The thickness is 15μm-25μm; The maximum particle size D of the precursor material max The size ranges from 90μm to 150μm.

14. The method according to claim 13, characterized in that, The complexing agent includes at least one of ammonia and ethylenediaminetetraacetic acid.

15. The method according to claim 14, characterized in that, The median particle size D of the precursor material 50 It ranges from 17μm to 22μm.

16. The method according to claim 15, characterized in that, The median particle size D of the precursor material 50 It is 18μm-20μm.

17. The method according to claim 14, characterized in that, The maximum particle size D of the precursor material max The size ranges from 110μm to 130μm.

18. The method according to claim 17, characterized in that, The maximum particle size D of the precursor material max It is 115μm-120μm.

19. The method according to claim 13, characterized in that, At least one of the following conditions must be met: The loose bulk density (AD) of the precursor material is 0.4 g / cm³. 3 -0.9g / cm 3 ; The tap density TD of the precursor material is 1 g / cm³. 3 -1.4g / cm 3 ; The precursor material has a BET specific surface area of ​​100 m². 2 / g-170m 2 / g.

20. The method according to claim 19, characterized in that, The loose pack density (AD) of the precursor material is 0.55 g / cm³. 3 -0.75g / cm 3 ; The tap density (TD) of the precursor material is 1.15 g / cm³. 3 -1.25g / cm 3 ; The precursor material has a BET specific surface area of ​​115m². 2 / g-130m 2 / g.

21. A positive electrode active material, characterized in that, include: Matrix; A coating material located on at least a portion of the surface of the substrate, the coating material comprising the additives of any one of claims 1-12 or additives prepared by the method of any one of claims 13-20.

22. A positive electrode plate, characterized in that, Includes the positive electrode active material as described in claim 21.

23. A battery, characterized in that, Includes the positive electrode sheet as described in claim 22.

24. An electrical appliance, characterized in that, Includes the battery as described in claim 23.

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