Core-shell structure ternary precursor material, preparation method therefor and use thereof

Abstract

The present application provides a core-shell structure ternary precursor material, a preparation method therefor, and a use thereof. The core-shell structure ternary precursor material comprises a core and an outer shell, and further comprises a blocking layer between the core and the outer shell; the core comprises a first nickel-cobalt-manganese hydroxide, the outer shell comprises a second nickel-cobalt-manganese hydroxide, and the nickel content in the second nickel-cobalt-manganese hydroxide is less than the nickel content in the first nickel-cobalt-manganese hydroxide. The blocking layer in the core-shell structure ternary precursor material acts as a bridge between the core and the shell, and can hinder the separation of the core and the shell during a subsequent positive electrode material sintering process, thereby solving the phenomenon of stratification during the sintering process caused by a large difference in components in the core-shell material, improving the cycle stability and rate performance of a battery.

Description

A core-shell structure ternary precursor material and its preparation method and application Technical Field

[0001] The present application belongs to the field of battery technology and relates to a core-shell structure ternary precursor material and its preparation method and application. Background Art

[0002] Lithium-ion batteries, due to their high energy density, excellent rate capability, and low self-discharge, have become a widely used power and energy storage device in our lives. Currently, green new energy vehicles are becoming the industry's most promising development direction. Therefore, improving the battery life and energy storage capacity of lithium batteries in new energy vehicles, the energy density per unit volume of lithium battery materials, and battery safety and service life have become the most pressing technical issues in the industry. High-nickel cathode materials have attracted much attention due to their high specific capacity, but they also face challenges with poor cycling performance, rate capability, and safety, hindering their market adoption. These shortcomings of high-nickel materials primarily stem from the propensity for Li / Ni intercalation during cycling, and the resulting volume expansion and contraction during lithium insertion and extraction, which can cause the spherical structure to rupture and affect the material's cycling stability. Furthermore, high-nickel ternary materials tend to release oxygen during cycling, posing a significant safety risk to battery use.

[0003] In the related art, the stability of high-nickel materials is improved by doping and coating elements. For example, CN 113903908A discloses a high-nickel multi-element positive electrode material and its preparation method and application. The preparation method first obtains a nickel-cobalt-manganese precursor solution added with a metal dopant, and then condenses the precursor solution to obtain precursor particles; the precursor particles are contacted with the sprayed lithium source powder, crystallized to obtain aggregated secondary particles, and finally the secondary particles are mixed with a surface coating additive and sintered to obtain a high-nickel multi-element positive electrode material; since the preparation method completes the precursor synthesis and the sintering of the secondary particles in the same equipment, the cost is reduced, and the surface properties of the high-nickel material are avoided from being affected by the external environment, so that the obtained high-nickel multi-element positive electrode material has excellent cycle performance, good structural stability, and improves the high-temperature gas production problem.

[0004] In addition, the related art also discloses the use of a core-shell material with a high-nickel interior and a low-nickel exterior to improve the cycle stability of high-nickel materials. However, the ratio of the elements in the core and shell of the core-shell material is quite different, which leads to certain differences in the micromorphology of the material (primary particles, pore structure, stacking method, etc.). The core and shell are easily separated during the cycle, causing the positive electrode material to peel off, seriously affecting the cycle performance of the positive electrode material, and failing to fundamentally improve the cycle stability of the high-nickel material.

[0005] Based on the above research, it is necessary to provide a core-shell structure ternary precursor material, which has high stability and will not cause core and shell separation during the sintering process, thereby giving full play to the advantages of high capacity and high stability of the core-shell material.

[0006] Summary of the Invention

[0007] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0008] The present application provides a core-shell structure ternary precursor material and its preparation method and application. The blocking layer in the core-shell structure ternary precursor material acts as a bridge between the core and the shell, which can hinder the separation of the core and the shell during the subsequent sintering process of the positive electrode material, solves the stratification phenomenon caused by the large component differences during the sintering process of the core-shell material, and improves the cycle stability and rate performance of the battery.

[0009] In a first aspect, the present application provides a core-shell structure ternary precursor material, wherein the core-shell structure ternary precursor material comprises a core and an outer shell, and further comprises a blocking layer between the core and the outer shell;

[0010] The inner core includes a first nickel-cobalt-manganese hydroxide, and the outer shell includes a second nickel-cobalt-manganese hydroxide. The nickel content of the second nickel-cobalt-manganese hydroxide is less than the nickel content of the first nickel-cobalt-manganese hydroxide.

[0011] The ternary precursor material described in the present application is a core-shell structure, wherein the core is a high-nickel ternary material and the shell is a low-nickel ternary material, and a blocking layer is provided between the core and the shell. The setting of the blocking layer acts as a bridge, which enables the shell and the core to be tightly combined, thereby improving the overall stability of the material, and avoiding the phenomenon of stratification of the shell and the core during the subsequent sintering process due to the large difference in components when the core is high-nickel and the shell is low-nickel. During the charge and discharge cycle, the problem of microcracks at the intergranular boundaries of the core caused by lattice contraction / expansion induced by lithium ion insertion and extraction is improved, and the problem of secondary particle breakage, collapse of the internal structure of the crystal, and low lithium ion transmission rate caused by expansion from the inside to the outside is improved, thereby improving the cycle stability and rate performance of the battery.

[0012] In one embodiment, the blocking layer comprises a transition metal hydroxide.

[0013] The blocking layer described in the present application includes transition metal hydroxide, but the transition metal element in the transition metal hydroxide does not include any one of nickel, cobalt or manganese, or a combination of at least two of them.

[0014] In one embodiment, the transition metal element in the transition metal hydroxide includes any one of Zr, Al, Mg, Ti or W, or a combination of at least two thereof.

[0015] In one embodiment, the thickness of the blocking layer is 0.1-3 μm, for example, 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm or 3 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0016] The thickness of the blocking layer described in this application will affect the bridging effect of the blocking layer. If the thickness of the blocking layer is too small, there is still a risk of separation between the core and the shell. If the thickness of the blocking layer is too large, after the material is prepared into a battery, during the battery cycle, the Li + The transmission between the inner and outer cores will be severely hindered, resulting in higher resistance of the material, thus affecting the cycle performance of the battery.

[0017] In one embodiment, the chemical formula of the core-shell structure ternary precursor material is Ni a Co b Mn c M (1-a-b-c) (OH)2, wherein 0.1≤a≤0.9, for example, it can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or 0.9, 0.01≤b≤0.6, for example, it can be 0.01, 0.1, 0.3, 0.5 or 0.6, 0.01≤c≤0.7, for example, it can be 0.01, 0.1, 0.3, 0.5 or 0.7, and M includes any one of Al, Zr, Mg, W, Ti, Cr or B or a combination of at least two of them.

[0018] In one embodiment, the particle size D50 of the core-shell structure ternary precursor material is 2-20 μm, for example, it can be 2 μm, 5 μm, 10 μm, 15 μm or 20 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] In one embodiment, the chemical formula of the first nickel-cobalt-manganese hydroxide is Ni x1 Co y1 Mn 1-x1-y1 (OH)2, wherein 0.10≤x1≤0.98, for example, it can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or 0.9, 0.02<y1<0.9, for example, it can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 or 0.8, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] In one embodiment, the particle size D50 of the core is 1.0-15 μm, for example, 1 μm, 3 μm, 5 μm, 7 μm, 9 μm, 11 μm, 13 μm or 15 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] In one embodiment, the ratio of the particle size D50 of the core-shell structure ternary precursor material to the particle size D50 of the core is (1-5):1, but does not include 1:1. For example, it can be 1.1:1, 1.5:1, 2:1, 2.5:1, 3:1, 4:1 or 5:1, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable.

[0022] The ratio of the particle size D50 of the core-shell structure ternary precursor material described in this application to the particle size D50 of the inner core should not be too large. If the thickness of the blocking layer is constant, the thickness of the outer shell will be relatively large, which will reduce the bridging effect of the blocking layer and affect the stability of the material after sintering.

[0023] In a second aspect, the present application provides a method for preparing the core-shell structure ternary precursor material as described in the first aspect, the preparation method comprising the following steps:

[0024] (1) mixing a first nickel-cobalt-manganese metal salt solution, a precipitant solution, and a complexing agent solution to perform a coprecipitation reaction to obtain a core;

[0025] (2) stopping the introduction of the first nickel-cobalt-manganese metal salt solution in step (1), and subjecting the blocking agent solution, the precipitant solution, and the complexing agent solution to a coprecipitation reaction to obtain a core having a surface coated with a blocking layer;

[0026] (3) Stop feeding the blocking agent solution in step (2), and subject the second nickel-cobalt-manganese metal salt solution, the precipitant solution, and the complexing agent solution to a coprecipitation reaction to obtain the core-shell structure ternary precursor material.

[0027] The coprecipitation reaction described in this application is divided into three stages, step (1) is the stage of preparing the core, step (2) is the stage of preparing the blocking layer, and step (3) is the stage of preparing the shell, and the metal salt solution introduced in the three stages can be changed.

[0028] In one embodiment, the blocking agent solution includes any one of zirconium sulfate solution, aluminum nitrate solution, magnesium sulfate solution, titanyl sulfate solution or ammonium tungstate solution, or a combination of at least two thereof.

[0029] In one embodiment, the coprecipitation reaction time in step (2) is 2-10 hours, for example, 2 hours, 4 hours, 6 hours, 8 hours or 10 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0030] In one embodiment, the pH of the coprecipitation reaction in step (2) is maintained in the range of 8-10.5, which means that the lowest pH during the coprecipitation reaction is above 8, for example, 8, 8.2, 8.4, 8.6, 8.8 or 9, and the highest pH is below 10.5, for example, 10.5, 10.3, 10.1, 9.9, 9.7 or 9.5. The concentration of the complexing agent in the system is maintained in the range of 2-10 g / L, which means that the lowest concentration of the complexing agent in the system is above 2 g / L, for example, 2 g / L, 2.5 g / L, 3 g / L, 3.5 g / L or 4 g / L, and the highest concentration of the complexing agent in the system is below 10 g / L, for example, 10 g / L, 9.5 g / L, 9 g / L, 8.5 g / L or 8 g / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable.

[0031] In one embodiment, the flow rate of the blocking agent solution in step (2) is 5-20 L / h, for example, 5 L / h, 10 L / h, 15 L / h or 20 L / h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0032] In one embodiment, the flow rate of the complexing agent solution in step (2) is 2-15 L / h, for example, it can be 2 L / h, 5 L / h, 10 L / h or 15 L / h, and the flow rate of the precipitant solution in step (2) is 5-20 L / h, for example, it can be 5 L / h, 10 L / h, 15 L / h or 20 L / h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0033] In one embodiment, in the first nickel-cobalt-manganese metal salt solution in step (1), the molar ratio of nickel ions, cobalt ions and manganese ions is x1:y1:1-x1-y1, wherein 0.10≤x1≤0.98, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or 0.9, 0.02<y1<0.9, for example, it can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 or 0.8, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0034] In one embodiment, in the second nickel-cobalt-manganese metal salt solution in step (3), the molar ratio of nickel ions, cobalt ions and manganese ions is x2:y2:1-x2-y2, wherein 0.10≤x2≤0.8, for example, it can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 or 0.8, 0.2<y2<0.9, for example, it can be 0.21, 0.3, 0.4, 0.5, 0.6, 0.7 or 0.8, but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable.

[0035] In one embodiment, 1<x1 / x2≤5, for example, it can be 1.1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, and 1<x1 / x2≤3 can be selected.

[0036] In one embodiment, the temperature of the coprecipitation reaction in step (1) is 45-70°C, for example, 45°C, 55°C, 65°C or 70°C, and the time is 40-80h, for example, 40h, 50h, 60h, 70h or 80h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] The coprecipitation reactions in step (1), step (2) and step (3) of the present application are all carried out at 45-70° C. and in an inert gas atmosphere.

[0038] In one embodiment, the pH of the coprecipitation reaction in step (1) is maintained in the range of 10-12, which means that the lowest pH during the coprecipitation reaction is above 10, for example, it can be 10, 10.2, 10.4, 10.6 or 10.8, and the lowest pH during the coprecipitation reaction is below 12, for example, it can be 12, 11.8, 11.6, 11.4, 11.2 or 11. The concentration of the complexing agent in the system is maintained in the range of 4-15 g / L, which means that the lowest concentration of the complexing agent in the system is above 4 g / L, for example, it can be 4 g / L, 5 g / L, 6 g / L, 7 g / L or 8 g / L, and the highest is below 15 g / L, for example, it can be 15 g / L, 14 g / L, 13 g / L, 12 g / L or 11 g / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable.

[0039] In one embodiment, the flow rates of the first nickel-cobalt-manganese metal salt solution in step (1) and the second nickel-cobalt-manganese metal salt solution in step (3) are independently 30-80 L / h, for example, 30 L / h, 50 L / h, 70 L / h or 80 L / h, but are not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0040] In one embodiment, the flow rate of the complexing agent solution in step (1) and step (3) is independently 5-20 L / h, for example, 5 L / h, 10 L / h, 15 L / h or 20 L / h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0041] In one embodiment, the flow rate of the precipitant solution in step (1) and step (3) is independently 10-30 L / h, for example, 10 L / h, 15 L / h, 20 L / h, 25 L / h or 30 L / h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0042] In one embodiment, the pH of the coprecipitation reaction in step (3) is maintained in the range of 8-11, which means that the pH during the coprecipitation reaction is at least 8, for example, 8, 8.5, 9 or 9.5, and at most below 11, for example, 11, 10.5 or 10. The concentration of the complexing agent in the system is maintained in the range of 3-12 g / L, which means that the concentration of the complexing agent in the system is at least 3 g / L, for example, 3 g / L, 4 g / L, 5 g / L, 6 g / L or 7 g / L, and at least below 12 g / L, for example, 12 g / L, 11 g / L, 10 g / L, 9 g / L or 8 g / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable.

[0043] In one embodiment, the concentration of total metal ions in the first nickel-cobalt-manganese metal salt solution in step (1) and the second nickel-cobalt-manganese metal salt solution in step (3) is independently 1.0-5.0 mol / L, for example, 1.0 mol / L, 2.0 mol / L, 3.0 mol / L, 4.0 mol / L or 5.0 mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0044] In one embodiment, the precipitant solution includes any one of sodium hydroxide, potassium hydroxide, sodium carbonate or potassium carbonate, or a combination of at least two thereof. The concentration of the precipitant solution is 1-10 mol / L, for example, 1 mol / L, 5 mol / L or 10 mol / L, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0045] In one embodiment, the complexing agent solution includes any one or a combination of at least two of ammonia, EDTA or oxalic acid, and the concentration of the complexing agent solution is 1-10 mol / L, for example, it can be 1 mol / L, 5 mol / L, 8 mol / L or 10 mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0046] As an optional technical solution of the preparation method described in this application, the preparation method comprises the following steps:

[0047] (1) mixing a first nickel-cobalt-manganese metal salt solution at a flow rate of 30-80 L / h, a precipitant solution at a flow rate of 10-30 L / h, and a complexing agent solution at a flow rate of 5-20 L / h, and performing a coprecipitation reaction for 40-80 hours, wherein the coprecipitation reaction temperature is 45-70° C., the pH is maintained in the range of 10-12, and the concentration of the complexing agent in the system is maintained in the range of 4-15 g / L, to obtain a core;

[0048] In the first nickel-cobalt-manganese metal salt solution, the molar ratio of nickel ions, cobalt ions and manganese ions is x1:y1:1-x1-y1, wherein 0.10≤x1≤0.98, 0.02<y1<0.9;

[0049] (2) stopping the introduction of the first nickel-cobalt-manganese metal salt solution in step (1), mixing the blocking agent solution at a flow rate of 5-20 L / h, the precipitant solution at a flow rate of 5-20 L / h, and the complexing agent solution at a flow rate of 2-15 L / h, and performing a coprecipitation reaction for 2-10 hours, wherein the pH of the coprecipitation reaction is maintained in the range of 8-10.5, and the concentration of the complexing agent in the system is maintained in the range of 2-10 g / L, to obtain a core with a surface coated with a blocking layer;

[0050] (3) stopping the introduction of the blocking agent solution in step (2), and subjecting the second nickel-cobalt-manganese metal salt solution, the precipitant solution, and the complexing agent solution to a coprecipitation reaction, wherein the pH of the coprecipitation reaction is maintained in the range of 8-11, and the concentration of the complexing agent in the system is maintained in the range of 3-12 g / L, to obtain the core-shell structure ternary precursor material;

[0051] In the second nickel-cobalt-manganese metal salt solution, the molar ratio of nickel ions, cobalt ions and manganese ions is x2:y2:1-x2-y2, wherein 0.10≤x2≤0.8, 0.2<y2<0.9, and 1<x1 / x2≤5.

[0052] In a third aspect, the present application provides a positive electrode material, which is obtained by mixing and sintering a lithium source and the core-shell structure ternary precursor material described in the first aspect.

[0053] In one embodiment, the sintering includes pre-sintering and calcining performed sequentially, the pre-sintering temperature is 400-600°C, for example, 400°C, 500°C or 600°C, and the time is 3-10h, for example, 3h, 5h or 10h, the calcining temperature is 700-800°C, for example, 700°C, 750°C or 800°C, and the time is 10-20h, for example, 10h, 15h or 20h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0054] In a fourth aspect, the present application provides a battery, comprising the positive electrode material as described in the third aspect.

[0055] Compared with the related art, this application has the following beneficial effects:

[0056] The present application sets a blocking layer between the inner core and the outer shell, so that the setting of the blocking layer acts as a bridge, thereby improving the overall stability of the material, avoiding the phenomenon of stratification of the outer shell and the inner core during the subsequent sintering process due to the large difference in components between the high-nickel inner core and the low-nickel outer shell. During the charge and discharge cycle, the problem of microcracks at the inner core crystal boundary caused by lattice contraction / expansion induced by lithium ion insertion and extraction is improved, and the secondary particle breakage, internal crystal structure collapse and low lithium ion transmission rate caused by expansion from the inside to the outside are caused, thereby improving the cycle stability and rate performance of the battery.

[0057] Still other aspects will become apparent upon reading and understanding the detailed description. DETAILED DESCRIPTION

[0058] The technical solution of the present application is further described below through specific implementation methods. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations of the present application.

[0059] Example 1

[0060] This embodiment provides a core-shell structure ternary precursor material, the core-shell structure ternary precursor material comprising a core and an outer shell, a blocking layer between the core and the outer shell, the core comprising a first nickel-cobalt-manganese hydroxide, the outer shell comprising a second nickel-cobalt-manganese hydroxide, the nickel content of the second nickel-cobalt-manganese hydroxide being less than the nickel content of the first nickel-cobalt-manganese hydroxide;

[0061] The blocking layer is zirconium hydroxide with a thickness of 0.5 μm;

[0062] The core-shell structure ternary precursor material is Ni with a particle size D50 of 4 μm. 0.48 Co 0.2 Mn 0.3 Zr 0.02(OH)2, the particle size D50 of the core is 2.5 μm, and the ratio of the particle size D50 of the core-shell structure ternary precursor material to the particle size D50 of the core is 1.6:1;

[0063] The preparation method of the core-shell structure ternary precursor material comprises the following steps:

[0064] (1) In an argon atmosphere, a first nickel-cobalt-manganese metal salt solution at a flow rate of 30 L / h, a liquid caustic soda at a flow rate of 10 L / h, and an ammonia solution at a flow rate of 5 L / h were mixed and coprecipitated for 40 hours. The temperature of the coprecipitation reaction was 45° C., the pH was maintained in the range of 11-12, and the concentration of the complexing agent in the system was maintained in the range of 4-8 g / L to obtain a particle size D50 of 2.5 μm and a chemical formula of Ni 0.7 Co 0.1 Mn 0.2 The core of (OH)2;

[0065] The first nickel-cobalt-manganese metal salt solution is a solution with a concentration of 1 mol / L prepared by nickel sulfate, cobalt sulfate and nickel sulfate according to a molar ratio of 0.7:0.1:0.2;

[0066] The blocking agent is a zirconium sulfate solution with a concentration of 0.5 mol / L;

[0067] (2) stopping the introduction of the first nickel-cobalt-manganese metal salt solution in step (1), mixing the blocking agent solution at a flow rate of 5 L / h, the liquid caustic soda at a flow rate of 55 L / h, and the ammonia solution at a flow rate of 25 L / h, and performing a coprecipitation reaction for 8 hours, wherein the pH of the coprecipitation reaction is maintained in the range of 9-11.0, and the concentration of the complexing agent in the system is maintained in the range of 3-7 g / L, to obtain a core having a surface coated with a blocking layer, wherein the thickness of the blocking layer is 0.5 μm;

[0068] (3) stopping the introduction of the blocking agent solution in step (2), and performing a coprecipitation reaction on the second nickel-cobalt-manganese metal salt solution, liquid alkali, and ammonia water, wherein the pH of the coprecipitation reaction is maintained in the range of 9-11, and the concentration of the complexing agent in the system is maintained in the range of 2-6 g / L, to obtain the core-shell structure ternary precursor material having a particle size D50 of 4 μm;

[0069] The second nickel-cobalt-manganese metal salt solution is a solution with a concentration of 1 mol / L prepared by nickel sulfate, cobalt sulfate and nickel sulfate according to a molar ratio of 0.34:0.33:0.33;

[0070] The concentration of the liquid caustic soda in step (1), step (2) and step (3) is 2 mol / L, and the concentration of the ammonia water is 1 mol / L.

[0071] Example 2

[0072] This embodiment provides a core-shell structure ternary precursor material, the core-shell structure ternary precursor material comprising a core and an outer shell, a blocking layer between the core and the outer shell, the core comprising a first nickel-cobalt-manganese hydroxide, the outer shell comprising a second nickel-cobalt-manganese hydroxide, the nickel content of the second nickel-cobalt-manganese hydroxide being less than the nickel content of the first nickel-cobalt-manganese hydroxide;

[0073] The blocking layer is aluminum hydroxide with a thickness of 2 μm;

[0074] The core-shell structure ternary precursor material is Ni with a particle size D50 of 15 μm. 0.75 Co 0.05 Mn 0.18 Al 0.02 (OH)2, the particle size D50 of the core is 10 μm, and the ratio of the particle size D50 of the core-shell structure ternary precursor material to the particle size D50 of the core is 1.5:1;

[0075] The preparation method of the core-shell structure ternary precursor material comprises the following steps:

[0076] (1) In a nitrogen atmosphere, a first nickel-cobalt-manganese metal salt solution at a flow rate of 60 L / h, a liquid caustic soda at a flow rate of 15 L / h, and an ammonia solution at a flow rate of 6 L / h were mixed and coprecipitated for 50 hours. The temperature of the coprecipitation reaction was 55° C., the pH was maintained in the range of 10.5-12, and the concentration of the complexing agent in the system was maintained in the range of 5-9 g / L to obtain a particle size D50 of 10 μm and a chemical formula of Ni 0.9 Co 0.0.05 Mn 0.05 The core of (OH)2;

[0077] The first nickel-cobalt-manganese metal salt solution is a solution with a concentration of 2 mol / L prepared by nickel sulfate, cobalt sulfate and nickel sulfate according to a molar ratio of 0.9:0.05:0.05;

[0078] (2) stopping the introduction of the first nickel-cobalt-manganese metal salt solution in step (1), mixing the blocking agent solution at a flow rate of 10 L / h, the liquid caustic soda at a flow rate of 8 L / h, and the ammonia solution at a flow rate of 8 L / h, and performing a coprecipitation reaction for 6 hours, wherein the pH of the coprecipitation reaction is maintained in the range of 9-10, and the concentration of the complexing agent in the system is maintained in the range of 5-9 g / L, to obtain a core with a surface coated with a blocking layer, wherein the thickness of the blocking layer is 2 μm;

[0079] The blocking agent is a 2 mol / L aluminum nitrate solution;

[0080] (3) stopping the introduction of the blocking agent solution in step (2), and performing a coprecipitation reaction on the second nickel-cobalt-manganese metal salt solution, liquid alkali, and ammonia water, wherein the pH of the coprecipitation reaction is maintained in the range of 9-10.5, and the concentration of the complexing agent in the system is maintained in the range of 6-8 g / L, to obtain the core-shell structure ternary precursor material having a particle size D50 of 15 μm;

[0081] The second nickel-cobalt-manganese metal salt solution is a solution with a concentration of 2 mol / L prepared by nickel sulfate, cobalt sulfate and nickel sulfate according to a molar ratio of 0.65:0.08:0.27;

[0082] The concentration of the liquid caustic soda in step (1), step (2) and step (3) is 5 mol / L, and the concentration of the ammonia water is 3 mol / L.

[0083] Example 3

[0084] This embodiment provides a core-shell structure ternary precursor material, the core-shell structure ternary precursor material comprising a core and an outer shell, a blocking layer between the core and the outer shell, the core comprising a first nickel-cobalt-manganese hydroxide, the outer shell comprising a second nickel-cobalt-manganese hydroxide, the nickel content of the second nickel-cobalt-manganese hydroxide being less than the nickel content of the first nickel-cobalt-manganese hydroxide;

[0085] The blocking layer is magnesium hydroxide with a thickness of 3 μm;

[0086] The core-shell structure ternary precursor material is Ni with a particle size D50 of 20 μm. 0.83 Co 0.05 Mn 0.15 Mg 0.02 (OH)2, the particle size D50 of the core is 15 μm, and the ratio of the particle size D50 of the core-shell structure ternary precursor material to the particle size D50 of the core is 1.33:1;

[0087] The preparation method of the core-shell structure ternary precursor material comprises the following steps:

[0088] (1) In a nitrogen atmosphere, a first nickel-cobalt-manganese metal salt solution is mixed at a flow rate of 80 L / h, a liquid caustic soda at a flow rate of 30 L / h, and an ammonia solution at a flow rate of 5 L / h, and a coprecipitation reaction is carried out for 80 hours. The temperature of the coprecipitation reaction is 60° C., the pH is maintained in the range of 11-12, and the concentration of the complexing agent in the system is maintained in the range of 10-15 g / L to obtain a particle size D50 of 15 μm and a chemical formula of Ni 0.98 Co 0.01 Mn 0.01 The core of (OH)2;

[0089] The first nickel-cobalt-manganese metal salt solution is a solution with a concentration of 8 mol / L prepared by nickel sulfate, cobalt sulfate and nickel sulfate according to a molar ratio of 0.98:0.01:0.01;

[0090] (2) stopping the introduction of the first nickel-cobalt-manganese metal salt solution in step (1), mixing the blocking agent solution at a flow rate of 20 L / h, the liquid caustic soda at a flow rate of 20 L / h, and the ammonia solution at a flow rate of 8 L / h, and performing a coprecipitation reaction for 10 hours, wherein the pH of the coprecipitation reaction is maintained in the range of 9-11, and the concentration of the complexing agent in the system is maintained in the range of 6-10 g / L, to obtain a core having a surface coated with a blocking layer, wherein the thickness of the blocking layer is 3 μm;

[0091] The blocking agent is a magnesium sulfate solution with a concentration of 5 mol / L;

[0092] (3) stopping the introduction of the blocking agent solution in step (2), and performing a coprecipitation reaction on the second nickel-cobalt-manganese metal salt solution, liquid alkali, and ammonia water, wherein the pH of the coprecipitation reaction is maintained in the range of 8-10.5, and the concentration of the complexing agent in the system is maintained in the range of 2-6 g / L, to obtain the core-shell structure ternary precursor material having a particle size D50 of 20 μm;

[0093] The second nickel-cobalt-manganese metal salt solution is a solution with a concentration of 8 mol / L prepared by nickel sulfate, cobalt sulfate and nickel sulfate according to a molar ratio of 0.5:0.2:0.3;

[0094] The concentration of the liquid alkali in step (1), step (2) and step (3) is 10 mol / L, and the concentration of the ammonia water is 8 mol / L.

[0095] Example 4

[0096] This embodiment provides a core-shell structure ternary precursor material. The core-shell structure ternary precursor material is the same as Example 2 except that the coprecipitation reaction time in step (2) is 2 hours, which causes the thickness of the blocking layer and the core-shell structure ternary precursor material to change accordingly.

[0097] Example 5

[0098] This embodiment provides a core-shell structure ternary precursor material, which is the same as Example 2 except that the coprecipitation reaction time in step (2) is 1 hour, which causes the thickness of the blocking layer and the core-shell structure ternary precursor material to change accordingly.

[0099] Example 6

[0100] This embodiment provides a core-shell structure ternary precursor material. The core-shell structure ternary precursor material is the same as Example 2 except that the coprecipitation reaction time in step (2) is 12 hours, which causes the thickness of the blocking layer and the core-shell structure ternary precursor material to change accordingly.

[0101] Example 7

[0102] This embodiment provides a core-shell structure ternary precursor material. The core-shell structure ternary precursor material is the same as Example 2 except that the concentration of the blocking agent solution in step (2) is 0.3 mol / L, which causes the thickness of the blocking layer and the core-shell structure ternary precursor material to change accordingly.

[0103] Example 8

[0104] This embodiment provides a core-shell structure ternary precursor material. The core-shell structure ternary precursor material is the same as Example 2 except that the concentration of the blocking agent solution in step (2) is 0.1 mol / L, which causes the thickness of the blocking layer and the core-shell structure ternary precursor material to change accordingly.

[0105] Example 9

[0106] This embodiment provides a core-shell structure ternary precursor material. The core-shell structure ternary precursor material is the same as Example 2 except that the concentration of the blocking agent solution in step (2) is 6 mol / L, which causes the thickness of the blocking layer and the core-shell structure ternary precursor material to change accordingly.

[0107] Example 10

[0108] This embodiment provides a core-shell structure ternary precursor material, wherein the particle size D50 of the core-shell structure ternary precursor is 20 μm, and the ratio of the particle size D50 of the core-shell structure ternary precursor material to the particle size D50 of the core is 2:1, and the rest is the same as that of Example 1;

[0109] The preparation method of the core-shell structure ternary precursor material is the same as that of Example 2, except that the coprecipitation reaction time in step (3) is prolonged so that the particle size D50 at the end of the reaction is 20 μm.

[0110] Example 11

[0111] This embodiment provides a core-shell structure ternary precursor material, wherein the particle size D50 of the core-shell structure ternary precursor is 30 μm, and the ratio of the particle size D50 of the core-shell structure ternary precursor material to the particle size D50 of the core is 3:1. Other than this, the other aspects are the same as those of Example 1.

[0112] The method for preparing the core-shell structure ternary precursor material is the same as that of Example 2, except that the coprecipitation reaction time in step (3) is prolonged so that the particle size D50 at the end of the reaction is 30 μm.

[0113] Comparative Example 1

[0114] This embodiment provides a core-shell structure ternary precursor material. The core-shell structure ternary precursor is the same as that of Example 2 except that it does not include a blocking layer.

[0115] The preparation method of the core-shell structure precursor material in this comparative example is the same as that in Example 2 except that step (2) is not performed.

[0116] The core-shell structure ternary precursor material obtained in the above examples and comparative examples was mixed evenly with 1.5 times the amount of LiOH·H2O in a mortar, pre-calcined in a muffle furnace at 400°C for 4 hours, and then further calcined at 800°C for 10 hours to obtain a positive electrode material; the positive electrode material was prepared into a positive electrode sheet, and a lithium ion battery was prepared with a lithium sheet, a lithium hexafluorophosphate electrolyte and a polypropylene separator. The electrochemical performance of the lithium ion battery was tested under the following test conditions: at 25°C, in a voltage range of 2.7-4.3V, and a current density of 0.1C.

[0117] The test results are shown in the following table:

[0118] Table 1

[0119] From the above table we can see that:

[0120] The material obtained in the present application has high stability, and the outer shell and the inner core will not separate after sintering, so that the battery has excellent cycle performance and the like; it can be seen from Example 1 and Comparative Example 1 that if a blocking layer is not added, sintering will cause the inner core and the outer shell to separate when preparing the positive electrode material, thereby affecting the material stability and the battery performance; it can be seen from Example 1 and Examples 4-9 that the time for the blocking agent solution of the present application to be passed through and the concentration of the blocking agent will affect the thickness of the blocking agent, thereby affecting the bridging effect of the blocking layer; it can be seen from Example 1 and Examples 10-11 that when the thickness of the blocking layer remains unchanged, if the particle size of the precursor material and the inner core is too large, the outer shell thickness will be too large, thereby affecting the bridging effect of the blocking layer and affecting the battery performance.

[0121] In summary, the present application provides a core-shell structured ternary precursor material, a preparation method and application thereof. The blocking layer in the core-shell structured ternary precursor material acts as a bridge between the core and the shell, which can hinder the separation of the core and the shell during the subsequent sintering process of the positive electrode material, solves the stratification phenomenon caused by the large component differences during the sintering process of the core-shell material, and improves the cycle stability and rate performance of the battery.

[0122] The above description is only a specific implementation method of the present application, but the protection scope of the present application is not limited thereto. Those skilled in the art should understand that any changes or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application fall within the protection scope and disclosure scope of the present application.

Claims

1. A core-shell structure ternary precursor material, comprising a core and an outer shell, and a blocking layer between the core and the outer shell; The inner core includes a first nickel-cobalt-manganese hydroxide, and the outer shell includes a second nickel-cobalt-manganese hydroxide, wherein the nickel content of the second nickel-cobalt-manganese hydroxide is less than the nickel content of the first nickel-cobalt-manganese hydroxide.

2. The core-shell structure ternary precursor material according to claim 1, wherein: The blocking layer includes a transition metal hydroxide; Optionally, the transition metal element in the transition metal hydroxide includes any one of Zr, Al, Mg, Ti or W, or a combination of at least two thereof; Optionally, the blocking layer has a thickness of 0.1-3 μm.

3. The core-shell structure ternary precursor material according to claim 1 or 2, wherein: The chemical formula of the core-shell structure ternary precursor material is Ni a Co b Mn c M (1-a-b-c) (OH)2, wherein 0.1≤a≤0.9, 0.01≤b≤0.6, 0.01≤c≤0.7, and M comprises any one of Al, Zr, Mg, W, Ti, Cr or B or a combination of at least two thereof; Optionally, the particle size D50 of the core-shell structure ternary precursor material is 2-20 μm; Optionally, the particle size D50 of the core is 1.0-15 μm; Optionally, the ratio of the particle size D50 of the core-shell structure ternary precursor material to the particle size D50 of the inner core is (1-5):1, but does not include 1:

1.

4. A method for preparing a core-shell structure ternary precursor material according to any one of claims 1 to 3, comprising the following steps: (1) mixing a first nickel-cobalt-manganese metal salt solution, a precipitant solution and a complexing agent solution to perform a coprecipitation reaction to obtain a core; (2) stopping the introduction of the first nickel-cobalt-manganese metal salt solution in step (1), and subjecting the blocking agent solution, the precipitant solution and the complexing agent solution to a coprecipitation reaction to obtain an inner core having a surface coated with a blocking layer; (3) Stop introducing the blocking agent solution in step (2), and subject the second nickel-cobalt-manganese metal salt solution, the precipitant solution and the complexing agent solution to a coprecipitation reaction to obtain the core-shell structure ternary precursor material.

5. The preparation method according to claim 4, wherein The coprecipitation reaction time in step (2) is 2-10 hours; Optionally, the pH of the coprecipitation reaction in step (2) is maintained in the range of 8-10.5, and the concentration of the complexing agent in the system is maintained in the range of 2-10 g / L; Optionally, the flow rate of the blocking agent solution in step (2) is 5-20 L / h; Optionally, the flow rate of the complexing agent solution in step (2) is 2-15 L / h, and the flow rate of the precipitant solution in step (2) is 5-20 L / h.

6. The preparation method according to claim 4 or 5, wherein: Step (1) In the first nickel-cobalt-manganese metal salt solution, the molar ratio of nickel ions, cobalt ions and manganese ions is x1:y1:1-x1-y1, wherein 0.10≤x1≤0.98, 0.02<y1<0.9; Optionally, in the second nickel-cobalt-manganese metal salt solution in step (3), the molar ratio of nickel ions, cobalt ions and manganese ions is x2:y2:1-x2-y2, wherein 0.10≤x2≤0.8, 0.2<y2<0.9; Optionally, 1<x1 / x2≤5; Optionally, the coprecipitation reaction temperature in step (1) is 45-70° C. and the reaction time is 40-80 h; Optionally, the pH of the coprecipitation reaction in step (1) is maintained in the range of 10-12, and the concentration of the complexing agent in the system is maintained in the range of 4-15 g / L.

7. The preparation method according to any one of claims 4 to 6, wherein: The flow rates of the first nickel-cobalt-manganese metal salt solution in step (1) and the second nickel-cobalt-manganese metal salt solution in step (3) are independently 30-80 L / h; Optionally, the flow rate of the complexing agent solution in step (1) and step (3) is independently 5-20 L / h; Optionally, the flow rate of the precipitant solution in step (1) and step (3) is independently 10-30 L / h; Optionally, the pH of the coprecipitation reaction in step (3) is maintained in the range of 8-11, and the concentration of the complexing agent in the system is maintained in the range of 3-12 g / L.

8. The preparation method according to any one of claims 4 to 7, comprising the steps of: (1) mixing a first nickel-cobalt-manganese metal salt solution at a flow rate of 30-80 L / h, a precipitant solution at a flow rate of 10-30 L / h, and a complexing agent solution at a flow rate of 5-20 L / h, and performing a coprecipitation reaction for 40-80 hours, wherein the coprecipitation reaction temperature is 45-70° C., the pH is maintained in the range of 10-12, and the concentration of the complexing agent in the system is maintained in the range of 4-15 g / L, to obtain a core; In the first nickel-cobalt-manganese metal salt solution, the molar ratio of nickel ions, cobalt ions and manganese ions is x1:y1:1-x1-y1, wherein 0.10≤x1≤0.98, 0.02<y1<0.9; (2) stopping the introduction of the first nickel-cobalt-manganese metal salt solution in step (1), mixing the blocking agent solution at a flow rate of 5-20 L / h, the precipitant solution at a flow rate of 5-20 L / h, and the complexing agent solution at a flow rate of 2-15 L / h, and performing a coprecipitation reaction for 2-10 hours, wherein the pH of the coprecipitation reaction is maintained in the range of 8-10.5, and the concentration of the complexing agent in the system is maintained in the range of 2-10 g / L, to obtain an inner core with a blocking layer coated on the surface; (3) stopping the introduction of the blocking agent solution in step (2), and subjecting the second nickel-cobalt-manganese metal salt solution, the precipitant solution and the complexing agent solution to a coprecipitation reaction, wherein the pH of the coprecipitation reaction is maintained in the range of 8-11, and the concentration of the complexing agent in the system is maintained in the range of 3-12 g / L, to obtain the core-shell structure ternary precursor material; In the second nickel-cobalt-manganese metal salt solution, the molar ratio of nickel ions, cobalt ions and manganese ions is x2:y2:1-x2-y2, wherein 0.10≤x2≤0.8, 0.2<y2<0.9, and 1<x1 / x2≤5.

9. A positive electrode material, wherein: The positive electrode material is obtained by mixing and sintering a lithium source and a core-shell structure ternary precursor material as described in any one of claims 1 to 3.

10. A battery, wherein: The battery comprises the positive electrode material as claimed in claim 9.

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