Additive and preparation method thereof, positive active material, positive pole piece, battery and electric equipment

Abstract

The invention provides an additive and a preparation method thereof, a positive electrode active material, a positive electrode plate, a battery and electric equipment, the additive comprises a compound shown in a formula I: Lax 'Zry' Mz 'Ow', the grain size of the additive meets # imgabs 0 # imgabs 1 #, and Vn10, Vn50 and Vn90 are corresponding grain sizes when the volume cumulative percentage of the grain size Vn of the additive reaches 10%, 50% and 90% respectively. The additive provided by the invention is small in grain size, when the additive is used as a coating material to be mixed with a positive electrode active material, the additive is more uniformly mixed with a base material, the surface of the base material can be uniformly coated with the additive, the additive has a better protection effect on the structure of the positive electrode active material, and the cycling stability of the positive electrode active material can be improved under high voltage.

Description

Technical Field

[0001] The present application relates to the field of batteries, and specifically, to additives and preparation methods thereof, positive electrode active materials, positive electrode sheets, batteries, and electrical equipment. Background Art

[0002] As a new energy product, lithium-ion batteries have been widely used in new energy vehicles and consumer electronic devices. Their energy density directly determines the product's endurance. To better meet consumer demand, the development of high-energy-density lithium-ion batteries is a crucial research direction. Among them, the development of high-voltage positive electrode materials is an effective strategy. However, when serving under high voltage conditions, the positive electrode active material will face safety issues such as crystal structure destruction (such as lattice oxygen production), battery failure caused by electrolyte decomposition, and explosion.

[0003] To address these issues, there is an urgent need to develop additives to improve the cycling stability of positive electrode active materials at high voltages. Common additives on the market are typically micron-sized, which results in uneven mixing with the matrix material and ineffective performance. Furthermore, commercially available additives are typically single-component materials, resulting in poor synergistic effects when different additives are physically mixed and used simultaneously. Summary of the Invention

[0004] The present application aims to solve one of the technical problems in the related art at least to a certain extent.

[0005] In a first aspect, the present application provides an additive, which comprises a compound represented by formula I:

[0006] La x’ Zr y’ M z’ O w’ Formula 1,

[0007] wherein 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 is the additive grain size V n The corresponding grain sizes when the cumulative volume percentages reach 10%, 50%, and 90%, respectively.

[0010] The additive proposed in this application has a small grain size. When used as a coating material and mixed with the positive electrode active material, the additive mixes more evenly with the base material and can be evenly coated on the base material surface, providing better protection for the structure of the positive electrode active material and improving the cycling stability of the positive electrode active material at high voltages. The additive proposed in this application also includes multiple metal elements, allowing for the simultaneous coating of the positive electrode active material with multiple elements, thereby enhancing the synergistic effect between the metal elements.

[0011] According to some embodiments of the present application, As a result, the grain size of the additive is small, which can achieve uniform coating of the base material.

[0012] According to some embodiments of the present 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 the present application, the median particle size D of the additive is 50 ≤0.5μm.

[0014] According to some embodiments of the present application, the average particle size d of the additive is 50 20nm≤d 50 ≤70nm, optionally, 30nm≤d 50 ≤60nm,d 50 It is the particle size corresponding to when the cumulative distribution of the number in the sample reaches 50%.

[0015] According to some embodiments of the present application, the K of the additive 90 Satisfies: 0.35≤K 90 ≤0.8, optionally, 0.45≤K 90 ≤0.65, where K 90 =(d 90 -d 10 ) / d 50 , d 10 is the particle size corresponding to the cumulative distribution of the number of samples reaching 10%, d 90 The particle size corresponding to the cumulative distribution of the number of particles in the sample reaches 90%. Therefore, the narrow particle size distribution makes the thickness of the additive material more uniform when it is coated on the surface of the positive electrode active material.

[0016] According to some embodiments of the present application, the BET specific surface area of the additive is 20 m 2 / g-40m 2 / g.

[0017] According to some embodiments of the present application, the roundness Q1 of a single particle of the additive is ≥80%, optionally, 85%≤Q1≤100%.

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

[0019] Therefore, the better roundness makes the nano-additive particles stacked tightly, and when used as a coating agent, the coating layer is more uniform.

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

[0021] mixing a La source, a Zr source, an M source, a precipitant, a complexing agent, and a solvent to obtain a mixed solution, and co-precipitating the mixed solution to obtain a slurry, wherein the co-precipitation temperature is 30° C.-65° C., and 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 by aggregation of primary particles, 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 comprises one or more of Ba, Ca, Fe, B, Zn, Al, Ga, Ge, Mo, Ti, Mn, Mg, and Sn, and the number of particles having an average particle size of less than or equal to 60 nm 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° C.-850° C.

[0026] The method provided by the present application is that the addition of nitrates can dope a certain amount of nitrate ions into the precursor material, and the nitrate ions can reduce the temperature required for sintering the precursor material, so that the additive finally obtained is looser and has a lower hardness. During the sintering process, the primary particles shrink and the nitrate ions decompose to produce a certain amount of gas, so that the additive is a loose and porous agglomeration of nanoscale primary particles. In summary, the present application can obtain nanoscale additives through a simple process, which can improve the uniformity of mixing with the matrix material when used to coat the positive electrode active material matrix, improve the coating effect on the positive electrode active material, improve the structural stability of the positive electrode active material, and improve the cycle performance of the positive electrode active material under high pressure.

[0027] According to some embodiments of the present application, the molar concentration of the complexing agent in the mixed solution is 0.05 mol / L-0.5 mol / L.

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

[0029] According to some embodiments of the present application, the median particle size D of the precursor material is 50 The particle size of the precursor material is 15 μm-25 μm, optionally 17 μm-22 μm, and further optionally 18 μm-20 μm. Therefore, since the hardness of the precursor material is relatively low, even if the median particle size of the precursor material is relatively large, it can be crushed into nano-sized additives through the crushing process, thereby reducing the complexity of the process.

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

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

[0032] The bulk density AD of the precursor material is 0.4 g / cm 3 -0.9g / cm 3 , optional 0.55g / cm 3 -0.75g / cm 3 ;

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

[0034] The BET specific surface area of the precursor material is 100 m 2 / g-170m 2 / g, optional 115m 2 / g-130m 2 / g.

[0035] Therefore, the sintering process is guaranteed to have a higher loading capacity, which is beneficial to increasing the output and is suitable for industrial production.

[0036] A third aspect of the present application provides a positive electrode active material comprising: a substrate; and a coating material, the coating material being located on at least a portion of the surface of the substrate, the coating material comprising the additive provided in the first aspect of the present application or the additive prepared by the method provided in the second aspect of the present application. Thus, the positive electrode active material has good structural stability and cycling performance.

[0037] The fourth aspect of the present application provides a positive electrode plate, comprising the positive electrode active material provided in the third aspect of the present application.

[0038] The fifth aspect of the present application provides a battery, comprising the positive electrode plate provided by the fourth aspect of the present application.

[0039] The sixth aspect of the present application provides an electrical device, including the battery provided in the fifth aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0041] Figure 1 A schematic flow chart of a method for preparing an additive according to an embodiment of the present application is shown.

[0042] Figure 2 The scanning electron microscope image of the precursor material prepared in Example 1 at 30K magnification is shown.

[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 The scanning electron micrograph of the additive prepared in Example 1 is shown.

[0046] Figure 6 Shows a schematic diagram of particle size measurement using Nano Measurer software.

[0047] Figure 7 Shows Figure 6 Particle size distribution diagram after measurement. DETAILED DESCRIPTION

[0048] The embodiments of the present application are 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 limiting the present application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this area or according to the product specifications. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0049] In a first aspect, the present application provides an additive, which comprises a compound represented by formula I:

[0050] La x’ Zr y’ M z’ O w’ Formula 1,

[0051] wherein 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 is the additive grain size V n The corresponding grain sizes when the cumulative volume percentage reaches 10%, 50%, and 90% respectively

[0054] 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 evenly, which has a better protective effect on 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 additives proposed in this application are coated on the surface of the positive electrode active material, which can reduce the phase change of the positive electrode active material under high voltage, reduce the side reaction between the positive electrode active material and the electrolyte, and improve the cycle performance of the battery. 3 + It can stabilize the layered structure of the positive electrode active material at high voltage, reduce the oxidizability of the surface of the positive electrode active material, prevent the transformation to the spinel structure or rock salt structure, and reduce the decomposition of the electrolyte; Zr 4+A stable oxide layer can be formed, reducing the occurrence of phase transitions. Selecting the appropriate M element plays a role in reinforcing the material. The additive proposed in this application includes multiple metal elements, enabling the coating of the positive electrode active material with multiple elements in one step, enhancing the synergistic effect between the metal elements.

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

[0057] As an example, Vn 10 Can be etc., or can be within the range of any of the above numerical values.

[0058] As an example, Vn 50 Can be etc., or can be within the range of any of the above numerical values.

[0059] As an example, Vn 90 Can be etc., or can be within the range of any of the above numerical values.

[0060] According to some specific embodiments of this application,

[0061] According to some embodiments of the present 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 can be any range of the above values. 10 、Vn 50 、Vn 90 When the Kn of the additive is within the range defined in this application, 90 Within the scope defined in this application, the additive has a small grain size and is more evenly distributed. When mixed with the matrix material, the uniformity can be further improved, so that the additive is evenly 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 the present application, 1<Kn 90 <2.5.

[0063] According to some embodiments of the present application, the median particle size D of the additive is 50 ≤0.5μm, D 50 It is the particle size corresponding to when the cumulative distribution of the number in the sample reaches 50%.

[0064] In the present application, the volume average particle size of the additive can be measured by Malvern laser particle size analyzer Mastersizer 3000.

[0065] As an example, the median particle size D of the additive 50 The thickness may be 0.4 μm, 0.3 μm, 0.2 μm, 0.1 μm, 0.05 μm, 0.04 μm, 0.01 μm, or the like, or may be within a range consisting of any of the above values.

[0066] According to some specific embodiments of the present application, the average particle size d of the additive is 50 Can be 20nm-70nm, d 50 The particle size corresponding to the cumulative distribution of the number of particles in the sample reaches 50%. For example, it can be 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, etc., or can be a range consisting of any of the above values.

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

[0068] As a result, the grain size and particle diameter of the additive are both smaller, and when mixed with the matrix material, the mixing is more uniform, the coating effect on the matrix is better, and the structural stability of the positive electrode active material can be improved.

[0069] According to some embodiments of the present application, the K of the additive 90 Satisfies: 0.35≤K 90 ≤0.8, where K 90 =(d 90 -d 10 ) / d 50 , d 10 is the particle size corresponding to the cumulative distribution of the number of samples reaching 10%, d 90 The particle size corresponding to the cumulative distribution of the number of samples reaches 90%. Therefore, the narrow particle size distribution makes the thickness of the additive material more uniform when it is coated on the surface of the positive electrode material.

[0070] In this application, d 10 d 50 d90 It can be measured by Nano Measurer, and 100 relatively independent particles are selected for measurement and the average value is taken.

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

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

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

[0074] In the present application, the BET specific surface area of the additive can be obtained by testing with a Tristar II 3020 specific surface area tester manufactured by Micromertics Corporation of the United States.

[0075] As an example, the BET specific surface area of the additive may be 20 m 2 / g, 25m 2 / g、30m 2 / g、35m 2 / g, 40m 2 / g, etc., or may be within the 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 evenly and densely cover the surface of the positive electrode active material, reduce the direct contact between the positive electrode active material and the electrolyte, inhibit side reactions, and more closely combine with the positive electrode active material. During the charge and discharge process, when the volume of the positive electrode active material changes, the surface-coated additive is not easy to fall off, thereby extending the cycle life of the battery.

[0077] According to some embodiments of the present application, the roundness Q1 of a single particle of the additive is ≥80%.

[0078] In the present application, the particle roundness Q = the long axis of the particle / the short axis of the particle × 100%, the long axis of the particle is the length of the longest diagonal of the particle, and the short axis of the particle is the size of the shortest diagonal of the particle. The sizes of the longest diagonal and the shortest diagonal can be tested by scanning electron microscopy (SEM).

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

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

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

[0082] Therefore, by making Q1 and Q2 within the above range, better roundness allows the nano-additive particles to be packed tightly together, and when used as a coating agent, the coating layer is more uniform.

[0083] In the present 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 the major axis and minor axis of the single particle, 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 may be 85%, 90%, 95%, 100%, etc., or may be within a range consisting of any of the above values.

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

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

[0087] Mixing a La source, a Zr source, an M source, a precipitant, a complexing agent, and a solvent to obtain a mixed solution, and co-precipitating the mixed solution to obtain a slurry, wherein the co-precipitation temperature is 30° C. to 65° C., and 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 by aggregation of primary particles, 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 comprises one or more of Ba, Ca, Fe, B, Zn, Al, Ga, Ge, Mo, Ti, Mn, Mg, and Sn, and the number of particles having an average particle size of less than or equal to 60 nm 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° C.-850° C.

[0092] In the method provided by the present application, the addition of nitrates can dope a certain amount of nitrate ions into the precursor material, and the nitrate ions can reduce the temperature required for sintering the precursor material, so that the additive finally obtained is looser and has a lower hardness. The precursor material is formed by the agglomeration of nanometer-scale primary particles. During the sintering process, the primary particles shrink and the nitrate ions decompose to produce a certain amount of gas, so that the additive is formed by the agglomeration of loose and porous nanometer-scale primary particles. In summary, the present application can obtain nanometer-scale additives through a simple process, which can improve the uniformity of mixing with the matrix material when used to coat the positive electrode active material matrix, improve the coating effect on the positive electrode active material, improve the structural stability of the positive electrode active material, and improve the cycle performance of the positive electrode active material.

[0093] The method provided in this application is described in detail below. Figure 1 , the method comprising:

[0094] S10: Mixing a La source, a Zr source, a M source, a precipitant, a complexing agent, and a solvent to obtain a mixed solution, and co-precipitating the mixed solution to obtain a slurry.

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

[0096] By controlling the amount of nitrate added, the content of nitrate in the precursor material can be controlled, and the sintering temperature of the precursor material can be lowered during sintering, so that the final additive is looser and has a lower hardness.

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

[0098] According to some embodiments of the present application, the concentration of the metal salt solution can be 0.5 mol / L-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 a range consisting of any of the above values.

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

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

[0101] According to some embodiments of the present 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 a range consisting of any of the above values.

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

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

[0104] According to some embodiments of the present application, the molar concentration of the complexing agent in the mixed solution 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 a range consisting of any of the above numerical values.

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

[0106] According to some embodiments of the present application, the pH value of the reaction base solution is 9.5-11.5.

[0107] According to some embodiments of the present application, the reaction temperature of the co-precipitation is 30° C.-65° C., and the stirring speed can be 300 rpm-800 rpm.

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

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

[0110] S20: Aging, washing, drying, and crushing the slurry to obtain a precursor material

[0111] In this step, the washing method is rinsing or rinsing and pulping are performed alternately. The washing water temperature used during washing is 15°C-80°C, the rotation speed during pulping is 300rpm-700rpm, and the pulping time is 0.3h-2h.

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

[0113] According to some embodiments of the present application, drying can be performed in a blast oven, with a drying temperature of 100° C.-180° C. and a drying time of 3 h-24 h.

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

[0115] According to some embodiments of the present application, the median particle size D of the precursor material is 50 The thickness may be 15 μm to 25 μm, for example, 15 μm, 17 μm, 19 μm, 21 μm, 23 μm, 25 μm, etc., or may be within a range consisting of the aforementioned values.

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

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

[0118] According to some embodiments of the present application, the maximum particle size D of the precursor material is max The thickness is 90 μm to 150 μm, for example, 90 μm, 110 μm, 130 μm, 150 μm, etc., or may be within the range of the above numerical values.

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

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

[0121] Therefore, the particle size of the precursor material is generally small, which is conducive to the preparation of nano-scale additives.

[0122] In this application, the D of the precursor material 50 、Dmax It can be obtained by testing with Malvern Laser Particle Sizer 3000.

[0123] According to some embodiments of the present application, the bulk density AD of the precursor material may be 0.4 g / cm 3 -0.9g / cm 3 , for example, it can be 0.4 g / cm 3 , 0.5g / cm 3 , 0.6g / cm 3 , 0.7g / cm 3 , 0.8g / cm 3 , 0.9g / cm 3 etc., or may be within the range consisting of the above numerical values.

[0124] According to some embodiments of the present application, the bulk density AD of the precursor material may be 0.55 g / cm 3 -0.75g / cm 3 .

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

[0126] According to some embodiments of the present application, the tap density TD of the precursor material may be 1 g / cm 3 -1.4g / cm 3 , for example, it can be 1g / cm 3 , 1.2g / cm 3 , 1.3g / cm 3 , 1.4g / cm 3 etc., or may be within the range consisting of the above numerical values.

[0127] According to some embodiments of the present application, the tap density TD of the precursor material may be 1.15 g / cm 3 -1.25g / cm 3 .

[0128] In the present application, the tap density of the precursor material can be measured by a BT-30 tap density tester manufactured by Baxter.

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

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

[0131] In the present application, the BET specific surface area of the precursor material can be obtained by testing with a Tristar II 3020 specific surface area tester manufactured by Micromertics Corporation of the United States.

[0132] The bulk density, tap density and BET specific surface area of the precursor material of the present application are within the above ranges, which can ensure a higher loading capacity in the sintering process, is conducive to increasing the output, and is suitable for industrial production.

[0133] S30: Sintering and crushing the precursor material to obtain the additive, the sintering temperature is 600°C-850°C

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

[0135] As an example, the sintering time may be 600° C., 650° C., 700° C., 750° C., 800° C., 850° C., etc., or may be within a range consisting of any of the above values.

[0136] As an example, the holding time can be 2 hours, 5 hours, 8 hours, 11 hours, 14 hours, 15 hours, etc., or can be a range consisting of any of the above values.

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

[0138] The present application controls the nitrate content in the precursor material and sintering at a lower temperature to obtain an additive with small grain size and particle diameter. The additive is mixed more evenly with the matrix material and can evenly 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, the sintered material can be nano-sized by jet milling.

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

[0141] (1) The additive has a smaller grain size and particle diameter, and is more evenly mixed with the matrix material. It can evenly coat the surface of the matrix material, improve the structural stability of the matrix material, and improve the cycle performance of the material under high voltage.

[0142] (2) The grain size distribution and particle size distribution of the additive are more uniform. When mixed with the matrix material, the uniformity of the mixing can be further improved, so that the surface of the matrix material is evenly coated with the additive, thereby improving the overall performance of the matrix and reducing the performance degradation that may be caused by poor local coating.

[0143] (3) In the process of preparing additives, metal elements are uniformly co-precipitated 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 the soft agglomeration of nano-scale primary particles and is doped with a certain amount of nitrate, which is beneficial to lowering the sintering temperature and making the sintered material soft, which is beneficial to the subsequent nano-process, so that the nano-process can obtain additives with nano-scale particle size without complicated steps.

[0145] The third aspect of the present application provides a positive electrode active material, including a substrate; a coating material, wherein the coating material is located on at least a portion of the surface of the substrate, and the coating material includes the additive provided in the first aspect of the present application or the additive prepared by the method provided in the second aspect of the present application.

[0146] According to some embodiments of the present application, when the substrate is coated, the coating amount of the metal element in the additive can be 500ppm-5000ppm, for example, it can be 500ppm, 1000ppm, 2000ppm, 3000ppm, 4000ppm, 5000ppm, etc., or it can be a range composed of any of the above numerical values.

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

[0148] As an example, the matrix material may include a lithium-ion battery positive electrode active material, including but not limited to lithium cobalt oxide, high nickel ternary positive electrode active materials, lithium-rich manganese-based positive electrode active materials, etc.

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

[0150] The fourth aspect of the present application provides a positive electrode plate, comprising the positive electrode active material provided in the third aspect of the present application.

[0151] Typically, the positive electrode sheet may include 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 may include the above-mentioned positive electrode active material. Among them, the positive electrode current collector may include but is not limited to metal foil (such as aluminum foil and copper foil, etc.) or a composite current collector, etc., and the positive electrode active material layer may also include a binder and a conductive agent, etc. Among them, the specific types and sources of the binder and the conductive agent are not particularly limited, and those skilled in the art can flexibly select them according to actual needs. For example, the binder may include but is not limited to polyvinylidene fluoride and polyvinylidene fluoride, etc., and the conductive agent may include but is not limited to one or more of conductive carbon black, carbon nanotubes, graphene, etc.

[0152] The fifth aspect of the present application provides a battery, comprising the positive electrode plate provided by the fourth aspect of the present application.

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

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

[0155] The diaphragm may include, but is not limited to, polyethylene (PE) film, polypropylene (PP) film, PP / PE / PP composite film, composite ceramic diaphragm, rubber-coated diaphragm, and the like.

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

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

[0158] The specific types of the electrical equipment are not particularly limited, and those skilled in the art can flexibly select them according to actual needs. For example, they may include but are not limited to electronic equipment, household appliances, vehicles, and vertical take-off and landing aircraft.

[0159] The present invention will be described below with reference to specific examples. It should be noted that these examples are merely illustrative and do not limit the present invention in any way. Where specific techniques or conditions are not indicated in the examples, they are performed according to the techniques or conditions described in the literature in this area or according to the product specifications. Reagents or instruments used that do not indicate the manufacturer are conventional products that can be obtained commercially.

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

[0161] Example 1

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

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

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

[0165] The filter cake was placed in a blast oven at a drying temperature of 120°C for 12 hours to obtain a precursor material. The morphology of the precursor material is as follows: Figure 2 The XRD test results of the precursor material are shown in the attached Figure 3 , whose 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 a temperature of 700°C and kept warm for 8 hours to obtain a sintered material. The sintered material was crushed by jet milling to obtain a nano additive material. The XRD pattern of the additive is shown in FIG. Figure 4 As shown, the morphology of the additive is Figure 5 As shown, its chemical formula is La 0.5 Zr 0.45 Al 0.05 O 1.725 The crystalline phase of the nano additive material is La2Zr2O7 (PDF71-2363).

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

[0168] Uncoated lithium cobalt oxide material was used as the matrix, and was evenly mixed with nano-additives according to a metal element coating amount of 1000ppm. The material was sintered at 900℃ to obtain coated lithium cobalt oxide material, which was made into button batteries to investigate its cycle performance.

[0169] The preparation methods of the additives in Examples 2 to 10 and Comparative Examples 1 to 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: obtained by using Malvern laser particle size analyzer Mastersizer 3000.

[0172] 2. Morphology test: obtained by scanning electron microscope S-4800 model of Hitachi HITACHI of Japan.

[0173] 3. Specific surface area: measured using a Tristar II 3020 surface area tester from Micromertics, Inc., USA.

[0174] 4. Bulk density: obtained by testing with FS4-2 bulk density meter.

[0175] 5. Tap density: measured by the BT-30 tap density tester of Baxter.

[0176] 6.Vn 10 、Vn 50 、Vn 90 Measurements were performed on a Rigaku Smartlab 9KW rotating target diffractometer with a scanning range of 10-80°, voltage of 40 kV, current of 200 mA, step size of 0.02°, and scan time of 2° / min. Crystallite size statistics were calculated using the WPPF grain size distribution function in SmartLab Studio II software according to the Fundamental Parameter method (FP method).

[0177] Button battery assembly:

[0178] First, the positive electrode active material for non-aqueous electrolyte secondary batteries, acetylene black and polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 95:2.5:2.5, coated on aluminum foil and dried, and stamped into a positive electrode sheet with a diameter of 12 mm and a thickness of 120 μm using a pressure of 100 MPa. The positive electrode sheet was then 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; and the electrolyte uses an equal volume mixture of 1 mol / L LiPF6, ethylene carbonate (EC) and diethyl carbonate (DEC).

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

[0181] After preparing the button cell, let it sit for 24 hours. Once the open-circuit voltage stabilized, charge it at a current density of 20 mA / g to a cutoff voltage of 4.55 V. Continue constant-voltage charging at 4.55 V to a cutoff current of 0.024 mA. Then, discharge it at the same current density to a cutoff voltage of 3.0 V. Repeat this process once more. This battery is considered activated.

[0182] 7.Battery cycle performance

[0183] The battery was charged and discharged twice at a current density of 20 mA / g, with a cut-off voltage of 3.0-4.5 V, and activation was completed. Using the activated battery sample, a specified number of charge and discharge cycles, for example 50 times, was performed at a temperature of 45°C and a current density of 1C in the voltage range of 3.0-4.45V. As described above, the discharge specific capacity of each charge and discharge cycle was obtained by comparing the current density with the discharge time of each cycle. The cycle performance of the battery is characterized by the high-temperature capacity retention rate, where the high-temperature capacity retention rate = the discharge specific capacity at the specified number of cycles / the 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 by controlling the co-precipitation temperature, the nitrate content in the precursor, and the sintering temperature during the preparation process. By making the grain size within the range specified in this application, when mixed with the matrix material, the uniformity of the mixing can be improved, and the additive can be evenly 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] It can be seen from Examples 1 and 2 that when the types of M elements in the additive are different, by controlling the co-precipitation temperature, the content of nitrate in the precursor, and the sintering temperature, etc., an additive with a grain size within the range specified in this application can be obtained, thereby obtaining a battery with better cycle performance. This shows that as long as the grain size is controlled within the range to be protected by this application, additives with different metal elements can be obtained, thereby improving the uniformity of the mixing of the additive and the matrix material, improving the coating effect on the matrix material, and improving the stability of the matrix material.

[0189] It can be seen from the comparison between Example 1 and Example 3 that in the process of preparing the additive, the grain size Vn of the additive can be adjusted by adjusting the coprecipitation temperature and the molar concentration of ammonia water. 10 、Vn 50 and Vn 90 etc., and then adjust the Kn of the additive 90 , by making Kn 90 Within the preferred range of the present application, the uniformity of the 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 improving the cycle performance of the battery.

[0190] It can be seen from the comparison between Example 4 and Example 1 that the d of the additive can be adjusted by adjusting the coprecipitation temperature and the molar concentration of ammonia water. 50 The more ammonia water is used, the stronger the complexing ability is, the smaller the primary crystal size of the additive is, and the d 50 The smaller the d 50 Within the preferred range of the present 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 at high voltage can be improved, and the cycle performance of the battery can be improved.

[0191] It can be seen from Example 1, Example 5, Example 6, Comparative Example 1, and Comparative Example 2 that the content of nitrate in the precursor can be adjusted by adjusting the washing method. At the same sintering temperature, the more nitrate the content, the looser the final additive is, and the lower the hardness is. Then, by simple crushing, the nano additive can be obtained. The nano additive is evenly mixed with the matrix material, which can improve the coating effect on the matrix material, improve the stability of the matrix material under high voltage, and improve the cycle performance of the battery. If the content of nitrate in the precursor material is too little, the improvement effect on the precursor material and the additive is not obvious; if the content of nitrate in the precursor material is too much, it will melt during the sintering process, and the primary particle size of the precursor material is small and easy to agglomerate, resulting in the final additive grain size being increased.

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

[0193] As can be seen from Examples 1 and 8, when the metal element coated on the substrate surface is within the preferred range defined in this application, the stability of the positive electrode active material is improved and the battery cycle performance is better. If the content of the coated metal element is further increased, the thickness of the coating layer increases. During the battery cycle, 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] It can be seen from Comparative Example 3 that in the process of preparing the additive, if the sintering temperature is too high, the grain size, D 50 d 50 When mixed with the matrix, the uniformity of the mixture will be reduced, the coating effect on the matrix will be affected, and finally the cycle performance of the battery will be reduced.

[0195] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present 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 any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0196] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. An additive, characterized in that Including compounds shown in formula I: La x’ Zr y’ M z’ O w’ Formula Ι, wherein 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: Among them, Vn 10 、Vn 50 、Vn 90 is the additive grain size V n The corresponding grain sizes when the cumulative volume percentages reach 10%, 50%, and 90%, respectively.

2. The additive according to claim 1, characterized in that 3. The additive according to claim 1 or 2, characterized in that Kn 90 =(Vn 90 -Vn 10 ) / Vn 50 , 0.5<Kn 90 <3.5, optionally, 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 3, characterized in that The average particle size d of the additive 50 20nm≤d 50 ≤70nm, optionally, 30nm≤d 50 ≤60nm,d 50 It is the particle size corresponding to when the cumulative distribution of the number in the sample reaches 50%.

6. The additive according to claim 5, characterized in that K of the additive 90 Satisfies: 0.35≤K 90 ≤0.8, optionally, 0.45≤K 90 ≤0.65, where K 90 =(d 90 -d 10 ) / d 50 , d 10 is the particle size corresponding to the cumulative distribution of the number of samples reaching 10%, d 90 It is the particle size corresponding to when the cumulative distribution of the number in the sample reaches 90%.

7. The additive according to claim 6, characterized in that The BET specific surface area of the additive is 20 m 2 / g-40m 2 / g.

8. The additive according to claim 7, characterized in that The roundness Q1 of a single particle of the additive is ≥80%, optionally, 85%≤Q1≤100%.

9. The additive according to claim 8, characterized in that The average roundness Q2 of the plurality of particles of the additive is ≥85%, optionally, 90%≤Q2≤100%.

10. A method for preparing the additive according to any one of claims 1 to 9, characterized in that: include: mixing a La source, a Zr source, an M source, a precipitant, a complexing agent, and a solvent to obtain a mixed solution, and co-precipitating the mixed solution to obtain a slurry, wherein the co-precipitation temperature is 30° C.-65° C., and 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 by aggregation of primary particles, 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 comprises one or more of Ba, Ca, Fe, B, Zn, Al, Ga, Ge, Mo, Ti, Mn, Mg, and Sn, and the number of particles having an average particle size of less than or equal to 60 nm in the precursor material accounts for 50%-80%; The precursor material is sintered and crushed to obtain the additive, and the sintering temperature is 600° C.-850° C.

11. The method according to claim 10, characterized in that The molar concentration of the complexing agent in the mixed solution is 0.05 mol / L-0.5 mol / L.

12. The method according to claim 11, characterized in that The complexing agent includes at least one of ammonia water and ethylenediaminetetraacetic acid.

13. The method according to claim 12, characterized in that The median particle size D of the precursor material 50 It is 15μm-25μm, optionally 17μm-22μm, and further optionally 18μm-20μm.

14. The method according to claim 12, characterized in that The maximum particle size D of the precursor material max It is 90μm-150μm, optionally 110μm-130μm, and further optionally 115μm-120μm.

15. The method according to claim 10, characterized in that Meet at least one of the following conditions: The bulk density AD of the precursor material is 0.4 g / cm 3 -0.9g / cm 3 , optional 0.55g / cm 3 -0.75g / cm 3 ; The tap density TD of the precursor material is 1 g / cm 3 -1.4g / cm 3 , optional 1.15g / cm 3 -1.25g / cm 3 ; The BET specific surface area of the precursor material is 100 m 2 / g-170m 2 / g, optional 115m 2 / g-130m 2 / g.

16. A positive electrode active material, characterized in that include: matrix; A coating material is located on at least a portion of the surface of the substrate, and the coating material comprises the additive according to any one of claims 1 to 9 or the additive prepared by the method according to any one of claims 10 to 15.

17. A positive electrode plate, characterized in that: Comprising the positive electrode active material according to claim 16.

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

19. An electrical device, characterized in that: Including the battery according to claim 18.

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