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 the following compounds: M1 a Al b (TiO) c Ti d M2 e (PO4) f (OH) g Wherein, 1≤a≤2.5, 0.2≤b≤0.5, 1≤c≤1.5, 0.25≤d≤0.55, 0≤e≤0.2, 1.8≤f≤2.6, 0≤g≤1.0, M1 is selected from at least one of NH4, Na, and K, and M2 is selected from at least one of Ge, Ga, In, Y, Sc, Mg, Zr, Nb, Mn, Co, Ni, Mo, and W. The additive of this application can react with residual lithium on the surface of the cathode material to form a lithium-based fast-ion conductor layer with a NASICON structure. This conductor layer can reduce interfacial impedance and increase the diffusion rate of lithium ions, thereby improving the capacity, cycle performance, and rate performance of the cathode material.

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] With the rapid development of the new energy industry, especially the widespread application of electric vehicles and energy storage systems, higher requirements have been placed on the energy density, rate performance, and cycle life of lithium-ion batteries. As a core component of lithium batteries, the cathode material directly affects the overall performance of the battery. To address these issues, researchers have begun to focus on optimizing the structure and interface properties of cathode materials by introducing functional additives.

[0003] Currently, most additive materials on the market are single-component materials, which often require the mechanical mixing of multiple materials before use. This can lead to localized enrichment of elements and poor mixing uniformity, thus affecting the performance. Furthermore, a single additive can only improve a single property of the cathode material, such as capacity. In addition, the preparation process of high-performance nano-additives often involves sintering, milling, spraying, and other processes, which are lengthy and complex, resulting in high prices and limiting the possibility of large-scale commercial application. 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: M1 a Al b (TiO) c Ti d M2 e (PO4) f (OH) g Formula I, Wherein, 1≤a≤2.5, 0.2≤b≤0.5, 1≤c≤1.5, 0.25≤d≤0.55, 0≤e≤0.2, 1.8≤f≤2.6, 0≤g≤1.0, M1 is selected from at least one of NH4, Na, and K, and M2 is selected from at least one of Ge, Ga, In, Y, Sc, Mg, Zr, Nb, Mn, Co, Ni, Mo, and W.

[0006] The additives described in this application can react with residual lithium on the surface of the cathode material to form a lithium-based fast-ion conductor layer with a NASICON structure. This conductor layer can reduce interfacial impedance and increase the diffusion rate of lithium ions, thereby improving the capacity, cycle performance, and rate performance of the cathode material.

[0007] According to some embodiments of this application, the XRD pattern of the additive has a bimodal distribution, including a first characteristic peak at 2θ of 10°~20° and a second characteristic peak at 2θ of 20°~40°; the peak area of ​​the first characteristic peak is S1, and the peak area of ​​the second characteristic peak is S2, wherein S1 and S2 satisfy at least one of the following conditions: S1 / S2 is 25%~65%; S1 / (S1+S2) is 20%~45%.

[0008] According to some embodiments of this application, the median particle size D of the additive is... 50 Less than 5 μm.

[0009] According to some embodiments of this application, the K of the additive 90 Satisfy: 0.35≤K 90 ≤0.8; Among them, 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%.

[0010] According to some embodiments of this application, the primary grain size D of the additive is... PS50 Satisfying 20 nm < D PS50 <200 nm.

[0011] According to some embodiments of this application, the primary grain size K of the additive is... PS90 Satisfying 0.5 < K PS90 <1.0; Among them, K PS90 =(D PS90 -D PS10 ) / D PS50 D PS10 D represents the primary grain size when the cumulative distribution of the number of grains in the sample reaches 10%. PS50 D represents the primary grain size when the cumulative distribution of the number of grains in the sample reaches 50%. PS90 This refers to the primary grain size when the cumulative distribution of the quantity in the sample reaches 90%.

[0012] According to some embodiments of this application, the additive has a BET specific surface area of ​​20 m². 2 / g~90 m 2 / g.

[0013] A second aspect of this application provides a method for preparing the additive provided in the first aspect of this application, the method comprising: The mixed metal salt solution, phosphorus source solution, and pH adjuster are mixed to obtain a mixed solution; The mixture is filtered, and the filter cake is collected. The filter cake is dried and crushed to obtain the additive. The mixed metal salt solution contains aluminum salt, titanium salt, and optionally M2 salt containing the M2 element; The phosphorus source solution contains a phosphorus source; M1 is present in the phosphorus source solution and / or the pH adjuster; The amount of phosphorus in the phosphorus source solution is P. mol The amount of metal element contained in the mixed metal salt solution is M. mol P mol and M mol Satisfying 1≤P mol / M mol ≤2; the pH value of the mixed solution is 4.5~9.0.

[0014] The method provided in this application obtains an additive satisfying Formula I by adjusting the molar ratio of phosphorus in the phosphorus source solution and metal elements in the mixed metal salt solution to meet the above conditions, while maintaining the pH value of the solution during the mixing process to meet the above conditions. When coating the cathode material, this additive can partially absorb residual lithium in the material to form a fast-ion conductor layer with a NASICON structure in situ. This conductor layer reduces interfacial impedance and increases the diffusion rate of lithium ions, thereby significantly improving the capacity, cycle performance, and rate performance of the cathode material, and enhancing overall battery performance. Furthermore, this preparation process is simple, has good compatibility with large-scale production equipment, is low-cost, and can be applied on a large scale.

[0015] According to some embodiments of this application, the aluminum salt includes at least one of aluminum sulfate, aluminum nitrate, and aluminum chloride; The titanium salt includes titanium tetrachloride and / or titanium oxysulfate; The phosphorus source includes at least one of phosphoric acid, ammonium dihydrogen phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, ammonium monohydrogen phosphate, sodium monohydrogen phosphate, potassium monohydrogen phosphate, ammonium phosphate, sodium phosphate, and potassium phosphate. The pH adjuster includes at least one of sodium hydroxide, potassium hydroxide, ammonia, sulfuric acid, phosphoric acid, hydrochloric acid, and nitric acid.

[0016] According to some embodiments of this application, the total concentration of metal salts in the mixed metal salt solution is 0.5 mol / L to 3 mol / L; The phosphorus source concentration in the phosphorus source solution is 0.5 mol / L to 4 mol / L; The concentration of the pH adjuster is 5 mol / L to 15 mol / L.

[0017] According to some embodiments of this application, the mixing process includes: The phosphorus source solution and part of the pH adjuster are added to the reaction vessel, stirring is started, and the temperature is raised to the reaction temperature; The mixed metal salt solution and the remaining pH adjuster are added to the reaction vessel to obtain a mixed slurry; The mixed slurry is aged to obtain the mixed liquid.

[0018] According to some embodiments of this application, the preset pH value is 4.5~9.0; The pH value of the mixed slurry is 4.5~9.0; The reaction temperature is 30℃~90℃; The stirring speed is 400 rpm to 1200 rpm; The aging process is carried out at a temperature of 25℃ to 70℃ for a time of 0.2 h to 2 h.

[0019] A third aspect of this application provides a method for preparing a positive electrode active material, comprising: heat-treating a positive electrode matrix active material with an additive provided in the first aspect of this application. The positive electrode active material prepared by this method exhibits high capacity, cycle performance, and rate performance.

[0020] According to some embodiments of this application, the heat treatment temperature is 300℃~1000℃ and the time is 5 h~15 h; The mass ratio of the additive to the positive electrode matrix active material is 100 ppm to 3000 ppm; The fourth aspect of this application provides a positive electrode active material, which is prepared by the method for preparing positive electrode active materials described in the third aspect of this application.

[0021] The fifth aspect of this application provides a positive electrode sheet, including the positive electrode active material provided in the fourth aspect of this application.

[0022] The sixth aspect of this application provides a battery including the positive electrode provided in the fifth aspect of this application.

[0023] The seventh aspect of this application provides an electrical device, including the battery provided in the sixth aspect of this application. Attached Figure Description

[0024] 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: Figure 1 A flowchart of a method for preparing an additive according to an embodiment of this application is shown; Figure 2 The image shows a SEM image of the additive material prepared in Example 1 of this application; Figure 3 The XRD patterns of the additive materials prepared in Example 1 and Comparative Example 1 are shown in comparison. Figure 4 The image shows a software-recognized image of the primary grains of the additive material prepared in Example 1. Detailed Implementation

[0025] 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.

[0026] A first aspect of this application provides an additive comprising a compound represented by Formula I: M1 a Al b (TiO) c Ti d M2 e (PO4) f (OH) g Formula I, Wherein, 1≤a≤2.5, 0.2≤b≤0.5, 1≤c≤1.5, 0.25≤d≤0.55, 0≤e≤0.2, 1.8≤f≤2.6, 0≤g≤1.0, M1 is selected from at least one of NH4, Na, and K, and M2 is selected from at least one of Ge, Ga, In, Y, Sc, Mg, Zr, Nb, Mn, Co, Ni, Mo, and W.

[0027] For cathode materials with unstable surfaces, such as high-nickel ternary materials, they are prone to reacting with water and carbon dioxide in the air during storage and preparation, generating substances such as Li₂CO₃ and LiOH, which can be called "residual lithium". Residual lithium leads to a series of problems such as high interfacial impedance, gas generation, and poor cycle performance.

[0028] The additives described in this application can react with residual lithium on the surface of these cathode materials to form a lithium-based fast-ion conductor layer with a NASICON structure. This conductor layer can reduce interfacial impedance and increase the diffusion rate of lithium ions, thereby improving the capacity, cycle performance, and rate performance of the cathode material.

[0029] As an example, 'a' can be 1, 1.2, 1.4, 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, 2.5, etc., or a range of any of the above values.

[0030] As an example, b can be 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, etc., or a range of any of the above values.

[0031] As an example, c can be 1, 1.1, 1.2, 1.3, 1.4, 1.5, etc., or a range of any of the above values.

[0032] As an example, d can be 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, etc., or a range of any of the above values.

[0033] As an example, e can be 0, 0.05, 0.1, 0.15, 0.2, etc., or a range of any of the above values.

[0034] As an example, f can be 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, etc., or a range of any of the above values.

[0035] According to some specific embodiments of this application, the XRD pattern of the additive has a bimodal distribution, including a first characteristic peak at 2θ of 10°~20° and a second characteristic peak at 2θ of 20°~40°; The peak area of ​​the first characteristic peak is S1, and the peak area of ​​the second characteristic peak is S2. S1 and S2 satisfy at least one of the following conditions: S1 / S2 is 25%~65%; S1 / (S1+S2) is 20%~45%. The additive material has moderate crystallinity and moderate reactivity, thereby ensuring that the additive material can absorb residual lithium in the material and form a fast ion conductor layer with a NASICON structure in situ.

[0036] As an example, S1 / S2 can be 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, etc., or a range of any of the above values.

[0037] As an example, S1 / (S1+S2) can be 20%, 25%, 30%, 35%, 40%, 45%, etc., or it can be a range of any of the above values.

[0038] According to some embodiments of this application, the median particle size D of the additive is... 50 Less than 5 μm. D 50 This refers to the particle size corresponding to a cumulative distribution ratio of 50% in the sample. Therefore, the additive has an appropriate particle size, which is beneficial for uniform dispersion with the positive electrode active material, effectively eliminating residual lithium on the surface of the positive electrode active material, reducing interfacial impedance, improving the lithium-ion diffusion rate, and enhancing the capacity, cycle performance, and rate performance of the positive electrode active material. This avoids the negative effects of excessively large particle sizes on lithium content. + The increased diffusion path and impaired contact between the active material and the electrolyte lead to a decrease in electrical performance. As an example, the median particle size D of the additive... 50 The value can be 0.1 μm, 0.2 μm, 0.3 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 4.9 μm, etc., or can be a range of any of the above values, wherein preferably 0.3 μm < D. 50 <3 μm.

[0039] According to some embodiments of this application, the K of the additive 90 Satisfy: 1.2 < K 90 <2.0; 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%.

[0040] K of additives 90 Meeting the above conditions ensures that the additive particles have a uniform size and a certain gradation effect, resulting in a denser and more uniform packing of the additive and the cathode matrix material. This allows for the formation of a continuous and defect-free coating layer on the surface of the cathode matrix material during subsequent sintering, avoiding localized uneven coating or agglomeration caused by improper particle size distribution, which leads to "transport barriers" in large particle areas and "short circuits" in small particle areas. Furthermore, it exhibits better mechanical strength and is less prone to breakage during cycling.

[0041] As an example, K 90It can be 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2.0, etc., or it can be a range of any of the above values.

[0042] As an example, the median particle size D mentioned above can be obtained by adjusting the crushing conditions after drying during the preparation of the additive (e.g., the number of crushing cycles, crushing intensity, etc.). 50 and K 90 Additives.

[0043] In this application, the additive's D 10 D 50 D 90 It can be tested using the Malvern Mastersizer 3000 laser particle size analyzer.

[0044] According to some specific embodiments of this application, the primary grain size D of the additive is... PS50 Satisfying 20 nm < DPS 50 <200 nm. Therefore, aggregation is less likely to occur, and the resulting coating layer has a moderate thickness, which is beneficial for lithium-ion transport and the performance of active materials.

[0045] As an example, the primary grain size D of the additive PS50 The nm values ​​can be 30 nm, 40 nm, 50 nm, 60 nm, 80 nm, 100 nm, 120 nm, 140 nm, 150 nm, 160 nm, 190 nm, etc., or a range of any of the above values. Preferably, 40 nm < D. PS50 <120nm.

[0046] According to some specific embodiments of this application, the primary grain size K of the additive is... PS90 Satisfying 0.5 < K PS90 <1.0; where K PS90 =(D PS90 -D PS10 ) / D PS50 D PS10 D represents the primary grain size when the cumulative distribution of the number of grains in the sample reaches 10%. PS50 D represents the primary grain size when the cumulative distribution of the number of grains in the sample reaches 50%. PS90 This refers to the primary grain size when the cumulative distribution of the quantity in the sample reaches 90%. The primary grains of the additive in this application are nanoscale, and the primary grain size K... PS90 If the above conditions are met, the uniformity of the primary grains is appropriate, which can produce a gradation effect and uniformly coat the surface of the positive electrode active material.

[0047] As an example, the primary grain size K of the additive PS90 It can be 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1.0, etc., or a range of any of the above values. Preferably, 0.6 < K. PS90 <0.8.

[0048] In this application, SEM image analysis was performed on the additives. Using intelligent particle microscopic image analysis system software, 500 grains were randomly identified, and the D value was calculated by the software. PS10 D PS50 D PS90 Then according to formula K PS90 =(D PS90 -D PS10 ) / D PS50 Calculate K PS90 .

[0049] According to some specific embodiments of this application, the BET specific surface area of ​​the additive is 20 m². 2 / g~90 m 2 / g. Therefore, the additive has suitable surface activity, which is beneficial for forming a uniform coating layer and lithium-ion transport.

[0050] 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.

[0051] As an example, the BET specific surface area of ​​the additive can be 20 m². 2 / g、30m 2 / g、40m 2 / g, 50m 2 / g、60m 2 / g、70m 2 / g、80m 2 / g、90m 2 / g, etc., or a range consisting of any of the above values.

[0052] A second aspect of this application provides a method for preparing the additive provided in the first aspect of this application, the method comprising: The mixed metal salt solution, phosphorus source solution, and pH adjuster are mixed to obtain a mixed solution; The mixture is filtered, and the filter cake is collected. The filter cake is dried and crushed to obtain the additive. The mixed metal salt solution contains aluminum salt, titanium salt, and optionally M2 salt containing the M2 element; The phosphorus source solution contains a phosphorus source; M1 is present in the phosphorus source solution and / or the pH adjuster; The amount of phosphorus in the phosphorus source solution is Pmol, and the amount of metal in the mixed metal salt solution is Mmol. Pmol and Mmol satisfy 1≤Pmol / Mmol≤2. The pH value of the mixed treatment solution is 4.5~9.0.

[0053] The method provided in this application obtains an additive satisfying Formula I by adjusting the molar ratio of phosphorus in the phosphorus source solution and metal elements in the mixed metal salt solution to meet the above conditions, while maintaining the pH value of the solution during the mixing process to meet the above conditions. When coating the cathode material, this additive can partially absorb residual lithium in the material to form a fast-ion conductor layer with a NASICON structure in situ. This conductor layer reduces interfacial impedance and increases the diffusion rate of lithium ions, thereby significantly improving the capacity, cycle performance, and rate performance of the cathode material, and enhancing overall battery performance. Furthermore, this preparation process is simple, has good compatibility with large-scale production equipment, is low-cost, and can be applied on a large scale.

[0054] The method provided in this application is described in detail below. (Refer to...) Figure 1 The method includes: S100 Mixed Processing In this step, a mixed metal salt solution, a phosphorus source solution, and a pH adjuster are mixed to obtain a mixture. Thus, the additive prepared through co-precipitation reaction enables the metal elements to achieve uniform co-precipitation at the atomic level, avoiding the adverse effects of localized element enrichment on material properties.

[0055] According to some embodiments of this application, the mixed metal salt solution contains aluminum salt, titanium salt, and optionally an M2 salt containing the M2 element; The phosphorus source solution contains a phosphorus source; M1 is present in the phosphorus source solution and / or the pH adjuster; The amount of phosphorus in the phosphorus source solution is Pmol, and the amount of metal in the mixed metal salt solution is Mmol, wherein Pmol and Mmol satisfy 1≤Pmol / Mmol≤2.

[0056] By adjusting the molar ratio of phosphorus in the phosphorus source solution to that of the metal in the mixed metal salt solution to meet the above conditions, an additive that satisfies Formula I can be obtained.

[0057] As an example, Pmol / Mmol can be 1, 1.2, 1.4, 1.5, 1.6, 1.8, 2, etc., or can be a range of any of the above values.

[0058] According to some embodiments of this application, the aluminum salt includes at least one of aluminum sulfate, aluminum nitrate, and aluminum chloride; The titanium salt includes titanium tetrachloride and / or titanium oxysulfate; The phosphorus source includes at least one of phosphoric acid, ammonium dihydrogen phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, ammonium monohydrogen phosphate, sodium monohydrogen phosphate, potassium monohydrogen phosphate, ammonium phosphate, sodium phosphate, and potassium phosphate. The pH adjuster includes at least one of sodium hydroxide, potassium hydroxide, ammonia, sulfuric acid, phosphoric acid, hydrochloric acid, and nitric acid.

[0059] According to some embodiments of this application, the total concentration of metal salts in the mixed metal salt solution is 0.5 mol / L to 3 mol / L; the concentration of phosphorus source in the phosphorus source solution is 0.5 mol / L to 4 mol / L; and the concentration of the pH adjuster is 5 mol / L to 15 mol / L. This provides a suitable ratio of M1, Al, Ti, PO4, and OH to obtain an additive satisfying Formula I; it also ensures a moderate co-precipitation reaction rate among the three solutions, which is beneficial for forming an additive with uniform composition and complete crystal structure, while avoiding component segregation or particle morphology defects caused by local supersaturation.

[0060] As an example, the total concentration of metal salts in the mixed metal salt solution 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 a range of any of the above values. Preferably, it is 0.8 mol / L to 2 mol / L.

[0061] As an example, the concentration of phosphorus source in the phosphorus source solution can be 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, or a range of any of the above values. Preferably, it is between 1 mol / L and 3 mol / L.

[0062] As an example, the concentration of the pH adjuster can be 5 mol / L, 6 mol / L, 8 mol / L, 10 mol / L, 12 mol / L, 14 mol / L, 15 mol / L, or a range of any of the above values.

[0063] According to some embodiments of this application, the mixing process includes: S110 The phosphorus source solution and a portion of the pH adjuster are added to the reaction vessel, stirring is started, and the temperature is raised to the reaction temperature to adjust the pH of the phosphorus source solution to the preset pH value. This provides the initial chemical reaction environment for the reaction and ensures pH stability throughout the synthesis process.

[0064] According to some embodiments of this application, the preset pH value is 4.5 to 9.0, such as 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, etc., or can be a range of any of the above values. Preferably, it is 5.5 to 7.5. Therefore, a suitable pH value can be provided for the co-precipitation reaction, and the g value in the compound represented by Formula I can be controlled based on the adjusted pH value.

[0065] According to some embodiments of this application, the reaction temperature is 30℃~90℃, such as 30℃, 40℃, 45℃, 50℃, 60℃, 70℃, 80℃, 90℃, etc., or can be any range of the above values, preferably 45℃~70℃. This facilitates a thorough and rapid co-precipitation reaction, improving the generation efficiency and performance of the additive.

[0066] According to some embodiments of this application, the stirring speed is 400 rpm to 1200 rpm, such as 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, 1100 rpm, 1200 rpm, etc., or can be any range of the above values, preferably 600 rpm to 1000 rpm. This ensures uniform mixing of the liquid and avoids component segregation and particle agglomeration caused by excessively high local concentrations.

[0067] S120 adds the mixed metal salt solution and the remaining pH adjuster to the reactor to obtain a mixed slurry.

[0068] According to some embodiments of this application, the pH value of the mixed slurry is 4.5 to 9.0, for example, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, etc., or can be a range of any of the above values. Preferably, it is 5.5 to 7.5. This provides a suitable pH value for the co-precipitation reaction, and the g value in the compound represented by Formula I can be controlled based on the adjusted pH value.

[0069] S130 involves aging the mixed slurry to obtain the mixed liquid. Aging allows for a more complete reaction of the materials.

[0070] According to some embodiments of this application, the aging treatment is carried out at a temperature of 25°C to 70°C for a time of 0.2 h to 2 h. This ensures that the materials react fully.

[0071] As an example, the aging treatment temperature can be 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, etc., or can be a range of any of the above values.

[0072] As an example, the aging time can be 0.2 h, 0.5 h, 0.8 h, 1 h, 1.2 h, 1.5 h, 1.8 h, 2 h, etc., or can be a range of any of the above values.

[0073] S200 filtration In this step, the mixture is filtered to collect the filter cake. This facilitates the collection of the filter cake.

[0074] The filter cake collected after filtration can be washed with washing water to remove impurity ions carried over during the co-precipitation process. In some embodiments, the washing water is pure water at 30-95°C, and the washing is continued until the filtrate is neutral. The washing water temperature is preferably 45-80°C.

[0075] S300 Drying and Crushing Processing In this step, the filter cake is dried and crushed to obtain the additive.

[0076] In this application, no particular limitations are placed on the equipment and parameters for drying, which may include a blower oven, a vacuum oven, a tray dryer, etc. The drying temperature is 100-180℃, and the drying time is 3-24 hours. No particular limitations are placed on the equipment and parameters used for crushing, as long as it can process the dried material to the required particle size. The drying equipment may include a soybean milk maker, a roller mill, a colloid mill, a mechanical mill, an air jet mill, etc.

[0077] A third aspect of this application provides a method for preparing a positive electrode active material, comprising: heat-treating a positive electrode substrate active material with an additive provided in the first aspect of this application. The positive electrode active material prepared by this method exhibits high capacity, cycle performance, and rate performance. The additive of this application can react with residual lithium on the surface of the positive electrode substrate active material to form a lithium-based fast ion conductor layer with a NASICON structure. This conductor layer can reduce interfacial impedance and increase the diffusion rate of lithium ions, thereby improving the capacity, cycle performance, and rate performance of the positive electrode material.

[0078] According to some embodiments of this application, the heat treatment temperature is 300℃~1000℃, and the time is 5 h~15 h. This facilitates the reaction of the additive with the residual lithium on the surface of the positive electrode matrix active material, resulting in a positive electrode active material with high capacity, cycle performance, and rate performance.

[0079] As an example, the temperature of the heat treatment is 300℃, 400℃, 500℃, 600℃, 700℃, 800℃, 900℃, 1000℃, etc., or it can be a range of any of the above values.

[0080] According to some embodiments of this application, the mass ratio of the additive to the positive electrode matrix active material is 100 ppm to 3000 ppm, or can be any of the above values. Therefore, the additive can fully react with the residual lithium on the surface of the positive electrode matrix active material to obtain a positive electrode active material with high capacity, cycle performance, and rate performance.

[0081] As an example, the mass ratio of the additive to the positive electrode matrix active material is 100 ppm, 500 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, etc., or can be a range of any of the above values.

[0082] 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.

[0083] As an example, the positive electrode matrix active material can include positive electrode active materials for lithium-ion batteries. Examples include, but are not limited to, lithium iron phosphate, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.8 Co 0.15 Al 0.05 At least one of O2).

[0084] This application provides a fourth aspect of a positive electrode active material, which is prepared by the method for preparing positive electrode active materials described in the third aspect of this application. Therefore, the positive electrode active material of this application exhibits excellent capacity, cycle performance, and rate performance.

[0085] The fifth aspect of this application provides a positive electrode sheet, including the positive electrode active material provided in the fourth aspect of this application.

[0086] 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.

[0087] The sixth aspect of this application provides a battery including the positive electrode provided in the fifth aspect of this application.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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(oxalate-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).

[0092] The seventh aspect of this application provides an electrical device, including the battery provided in the sixth aspect of this application.

[0093] 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.

[0094] 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.

[0095] In the following examples, all raw materials are commercially available unless otherwise specified.

[0096] Example 1 1. According to the molar ratio of Al:Ti = 0.3:1.7, weigh aluminum sulfate and titanium oxysulfate and dissolve them in deionized water to prepare a 1 mol / L mixed salt solution A; 2. Dilute the phosphoric acid to obtain phosphorus source solution B with a concentration of 1.5 mol / L.

[0097] 3. Prepare ammonia solution with a concentration of 10 mol / L as conditioning solution C.

[0098] 4. Add phosphorus source solution B to the reactor, turn on the stirrer at 700 rpm, heat to 50℃, add regulator solution C to adjust the pH value of phosphorus source solution B to 6.0, add mixed metal salt solution A and pH regulator solution C in parallel to the reactor, and react at pH 6.0 to obtain slurry; At the end of the reaction, the amount of phosphorus (P) in the phosphorus source solution B added to the reaction vessel is P. mol The amount of substance M of the metal element contained in the mixed metal salt solution A mol Satisfy P mol / M mol =1.7 5. Stir and age the slurry obtained from the reaction at 50℃ for 1 hour to obtain aged slurry; 6. Wash the aged slurry with 50℃ pure water to obtain filter cake.

[0099] 7. Place the filter cake in a 120℃ forced-air drying oven and dry for 12 hours to obtain the dried material; 8. The obtained dried material is crushed using a colloid mill to obtain an additive material with the molecular formula: (NH4). 2.22 Al 0.3 (TiO) 1.36 Ti 0.34 (PO4) 2.40 .

[0100] Methods for determining molecular formula: The phosphorus (P) content in the samples was tested according to HG / T 6103-2022.

[0101] The Ti content in the samples was tested according to GB / T 6730.23-2006.

[0102] The content of Al and M2 elements was tested by ICP.

[0103] M1 and OH - To balance the valence state of the entire chemical formula.

[0104] The molecular formula was finally determined by calculating the consistency between the theoretical and measured P content.

[0105] SEM images of additive materials, such as Figure 2 As shown, the XRD pattern is as follows Figure 3 As shown, its spectrum has two peaks, where peak 1 is in the range of 10-20° of 2θ degree and peak 2 is in the range of 20°-40° of 2θ degree. By integrating the peak areas of the two peaks in the XRD spectrum, the area of ​​peak 1 is S1 and the area of ​​peak 2 is S2. S1 / S2 is 48% and S1 / (S1+S2) is 34%.

[0106] 9. According to the additive materials and LiNi 0.93 Co 0.02 Mn 0.05 The high-nickel ternary cathode material with O2 at a weight ratio of 1000ppm was mixed and sintered at 600℃ for 10h to obtain the modified high-nickel ternary cathode material.

[0107] 10. Assemble the modified high-nickel ternary cathode material into a coin cell.

[0108] The preparation methods of the additives in Examples 2-13 are the same as those in Example 1, with the differences detailed in Table 1. The particle size of the additives is controlled by adjusting the crushing parameters.

[0109] Comparative Example 1 The additive was prepared according to the method of Example 1, except that the pH value was 3.5 in step 4. The XRD pattern of the additive material is shown below. Figure 3 As shown, its spectrum has only one single peak located in the range of 2θ degrees: 20°-40°.

[0110] Comparative Example 2 The additive was prepared according to the method of Example 1, except that in step 4, the pH value was 9.5.

[0111] Comparative Example 3 The additive was prepared according to the method of Example 1, except that in step 4, P mol / M mol =2.5.

[0112] Comparative Example 4 The additive was prepared according to the method of Example 1, except that in step 4, P mol / M mol =0.8.

[0113] Test case 1. Particle size testing: The particle size D was tested using a Malvern Mastersizer 3000 laser particle size analyzer. 50 D90 and D 10 .

[0114] 2. Single grain test: SEM images are analyzed using intelligent particle microscopic image analysis system software to identify 500 grains, and the D value is calculated by the software. PS10 D PS50 D PS90 Then according to formula K PS90 =(D PS90 -D PS10 ) / D PS50 Calculate K PS90 .

[0115] 3. BET specific surface area: obtained by testing using a Tristar II 3020 specific surface area analyzer from Micromertics, USA.

[0116] 4. Half-cell performance testing method: 4.1 Assembly of button cells: (1) Modified LiNi 0.93 Co 0.02 Mn 0.05 O2 high-nickel ternary cathode material, acetylene black and polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 95:2.5:2.5, coated on aluminum foil and dried. The mixture was then stamped into a cathode sheet with a diameter of 12 mm and a thickness of 120 μm under a pressure of 100 MPa. The cathode sheet was then placed in a vacuum drying oven and dried at 120 °C for 12 h.

[0117] (2) 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 mixture of 1 mol / L LiPF6, ethylene carbonate (EC) and diethyl carbonate (DEC).

[0118] (3) The positive electrode, separator, negative electrode and electrolyte are assembled into a 2025 button cell in an Ar gas glove box with water content and oxygen content of less than 5 ppm to obtain an unactivated cell.

[0119] (4) 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 4.3 V, and then charge it at a constant voltage of 4.3 V to the cutoff current of 0.024 mA. Then discharge it at the same current density to the cutoff voltage of 3.0 V, and repeat the above process once more to obtain the activated cell. The activated cell will then be used for subsequent performance evaluation.

[0120] 4.2 The performance evaluation of button cells is as follows: Cyclic performance testing: At a temperature of 25℃, within a voltage range of 3.0-4.3V, the initial discharge capacity and cycle performance of the material were examined at 0.1C, and the rate performance was examined at a current density of 1C. Specifically: Capacity performance evaluation: Discharge capacity at a current density of 0.1C within a voltage range of 3.0-4.3V at 25℃.

[0121] Cycling performance: Capacity retention after 80 cycles at a current density of 0.1C within a voltage range of 3.0-4.3V and a voltage of 25℃.

[0122] Rate performance evaluation: Discharge capacity at a current density of 1C within a voltage range of 3.0-4.3V at 25℃.

[0123] Table 1

[0124] Table 2

[0125] As shown in Table 2, the battery performance of Examples 1-13 is generally better than that of Comparative Examples 1-4. This indicates that by controlling the pH value of the mixing system, the molar ratio of phosphorus in the phosphorus source solution to the metal elements in the mixed metal salt solution, etc., during the additive preparation process, the obtained additive meets the compound definition conditions shown in Formula I. It can react with residual lithium on the surface of the cathode material to form a lithium-based fast ion conductor layer with a NASICON structure. This conductor layer can reduce interfacial impedance and increase the diffusion rate of lithium ions, thereby improving the capacity, cycle performance, and rate performance of the cathode material.

[0126] As can be seen from Examples 1, 5 and 6, the S1 / S2 ratio is 25%~65%, and the S1 / (S1+S2) ratio is 20%~45%. The crystallinity and reactivity of the additive material are moderate, thus ensuring that the additive material can absorb residual lithium in the material and form a fast ion conductor layer with a NASICON structure in situ.

[0127] As can be seen from Examples 1 and 7, the D of the additive 50 A high D value, after forming a coating layer, increases the diffusion path of lithium ions and hinders the contact between the active material and the electrolyte, leading to a decrease in the material's electrical performance. 50 Battery performance is better when the thickness is less than 5 μm.

[0128] As can be seen from Examples 1, 8, and 9, K 90 High K values, large particle size range, and significant differences in particle size result in an excessively thick coating layer, with some areas being too thin. Large particles create "transmission barriers," while small particles create "short circuits," thus affecting material properties. When 1.2 < K...90 Battery performance is better when the value is less than 2.0.

[0129] As can be seen from Examples 1, 10, and 11, the primary grain size D PS50 Smaller grain size makes them prone to aggregation, resulting in lower uniformity of coating thickness. Simultaneously, the corresponding BET value is lower, leading to insufficient surface activity and reduced protection of the material and lithium-ion transport performance. Primary grain size D... PS50 A larger diameter results in a thicker coating layer, affecting the lithium-ion transport path and the performance of the active material. Simultaneously, the corresponding BET is higher, leading to higher surface activity and a greater susceptibility to side reactions. When 20 nm < D... PS50 <200 nm, BET specific surface area is 20 m² 2 / g~90 m 2 At a ratio of / g, the battery performance is better.

[0130] As can be seen from Examples 1, 12, and 13, the primary grain size K PS90 The grain size is relatively small, the uniformity is relatively high, the gradation effect is relatively low, and it is difficult to form a uniform coating; the primary grain size K PS90 A value that is too large leads to lower uniformity of the coating layer. When 0.5 < K PS90 Battery performance is better when the value is less than 1.0.

[0131] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is 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.

[0132] 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: M1 a Al b (TiO) c Ti d M2 e (PO4) f (OH) g , Wherein, 1≤a≤2.5, 0.2≤b≤0.5, 1≤c≤1.5, 0.25≤d≤0.55, 0≤e≤0.2, 1.8≤f≤2.6, 0≤g≤1.0, M1 is selected from at least one of NH4, Na, and K, and M2 is selected from at least one of Ge, Ga, In, Y, Sc, Mg, Zr, Nb, Mn, Co, Ni, Mo, and W; The additive has a bimodal distribution in its XRD pattern, including a first characteristic peak at 2θ of 10°~20° and a second characteristic peak at 2θ of 20°~40°. The peak area of ​​the first characteristic peak is S1, and the peak area of ​​the second characteristic peak is S2, wherein S1 and S2 satisfy at least one of the following conditions: S1 / S2 is 25%~65%; S1 / (S1+S2) is 20%~45%.

2. The additive according to claim 1, characterized in that, The median particle size D of the additive 50 Less than 5 μm.

3. The additive according to claim 1, characterized in that, The additive K 90 Satisfy: 1.2 < K 90 <2.0; Among them, 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%.

4. The additive according to claim 1, characterized in that, The primary grain size D of the additive PS50 Satisfying 20nm < D PS50 <200 nm; D PS50 This refers to the primary grain size when the cumulative distribution of the quantity in the sample reaches 50%.

5. The additive according to claim 1, characterized in that, K of the primary grain size of the additive PS90 Satisfying 0.5 < K PS90 <1.0; Among them, K PS90 =(D PS90 -D PS10 ) / D PS50 D PS10 D represents the primary grain size when the cumulative distribution of the number of grains in the sample reaches 10%. PS50 D represents the primary grain size when the cumulative distribution of the number of grains in the sample reaches 50%. PS90 This refers to the primary grain size when the cumulative distribution of the quantity in the sample reaches 90%.

6. The additive according to claim 1, characterized in that, The additive has a BET specific surface area of ​​20 m². 2 / g~90 m 2 / g.

7. A method for preparing the additive according to any one of claims 1 to 6, characterized in that, include: The mixed metal salt solution, phosphorus source solution, and pH adjuster are mixed to obtain a mixed solution; The mixture is filtered, and the filter cake is collected. The filter cake is dried and crushed to obtain the additive. The mixed metal salt solution contains aluminum salt, titanium salt, and optionally M2 salt containing the M2 element; The phosphorus source solution contains a phosphorus source; M1 is present in the phosphorus source solution and / or the pH adjuster; The amount of phosphorus in the phosphorus source solution is P. mol The amount of metal element contained in the mixed metal salt solution is M. mol P mol and M mol Satisfying 1≤P mol / M mol ≤2; The pH value of the mixed solution is 4.5~9.0; The aluminum salt includes at least one of aluminum sulfate, aluminum nitrate and aluminum chloride; The titanium salt includes titanium tetrachloride and / or titanium oxysulfate; The phosphorus source includes at least one of phosphoric acid, ammonium dihydrogen phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, ammonium monohydrogen phosphate, sodium monohydrogen phosphate, potassium monohydrogen phosphate, ammonium phosphate, sodium phosphate, and potassium phosphate. The pH adjuster includes at least one of sodium hydroxide, potassium hydroxide, ammonia, sulfuric acid, phosphoric acid, hydrochloric acid, and nitric acid.

8. The method according to claim 7, characterized in that, The total concentration of metal salts in the mixed metal salt solution is 0.5 mol / L to 3 mol / L; The phosphorus source concentration in the phosphorus source solution is 0.5 mol / L to 4 mol / L; The concentration of the pH adjuster is 5 mol / L to 15 mol / L.

9. The method according to claim 7, characterized in that, The mixing process includes: The phosphorus source solution and part of the pH adjuster are added to the reaction vessel, stirring is started, and the temperature is raised to the reaction temperature to adjust the pH value of the phosphorus source solution to the preset pH value. The mixed metal salt solution and the remaining pH adjuster are added to the reaction vessel to obtain a mixed slurry; The mixed slurry is aged to obtain the mixed liquid.

10. The method according to claim 9, characterized in that, The preset pH value is 4.5~9.0; The pH value of the mixed slurry is 4.5~9.0; The reaction temperature is 30℃~90℃; The stirring speed is 400 rpm to 1200 rpm; The aging process is carried out at a temperature of 25℃ to 70℃ for a time of 0.2 h to 2 h.

11. A method for preparing a positive electrode active material, characterized in that, include: The positive electrode substrate active material and the additives according to any one of claims 1 to 6 are subjected to heat treatment.

12. The method according to claim 11, characterized in that, The heat treatment temperature is 300~1000℃, and the time is 5 h~15 h; The mass ratio of the additive to the positive electrode matrix active material is 100 ppm to 3000 ppm.

13. A positive electrode active material, characterized in that, The positive electrode active material is prepared by the method for preparing positive electrode active material as described in claim 11 or 12.

14. A positive electrode plate, characterized in that, Includes the positive electrode active material as described in claim 13.

15. A battery, characterized in that, Includes the positive electrode sheet as described in claim 14.

16. An electrical appliance, characterized in that, Includes the battery as described in claim 15.

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