Positive electrode precursor having wide particle size distribution, preparation method therefor and use thereof

Abstract

Disclosed are a positive electrode precursor having wide particle size distribution, a preparation method therefor and a use thereof. The chemical general formula of the positive electrode precursor is NixCoyMn(1-x-y)Rz, wherein 0<x≤1, 0≤y<1, and 1≤z≤2; R comprises hydroxide and / or carbonate; and the positive electrode precursor having wide particle size distribution satisfies that: 0.9≤(D90-D10) / D50≤2. The positive electrode precursor material provided by the present application has a span (D90-D10) / D50 ranging from 0.9 to 2, achieving a wide range of particle size distribution, improving the tap density and the compression resistance of the positive electrode material.

Description

A positive electrode precursor with wide particle size distribution and its preparation method and application Technical Field

[0001] The embodiments of the present application relate to the field of lithium-ion battery technology, for example, a positive electrode precursor with a wide particle size distribution, a preparation method thereof, and an application thereof. Background Art

[0002] New energy vehicles can reduce carbon emissions. Hybrid electric vehicles, plug-in hybrid electric vehicles, and pure electric vehicles all require lithium-ion batteries as their electric drive systems. Ternary materials have become the primary cathode material for power batteries due to their high energy density and excellent rate performance. However, traditional ternary materials cannot meet the high energy density and long cycle life requirements of power batteries required by battery manufacturers.

[0003] Ternary precursor materials with wide particle size distribution (or binary precursor materials) have a certain gap between primary particles and secondary spherical particles, resulting in smaller gaps between particles, which can provide higher tap density and relatively higher energy density of positive electrode materials. Narrow particle size ternary precursor materials have better uniformity and are characterized by high output power and high cycle life, but their structural characteristics determine that their tap density improvement is limited.

[0004] For multiple secondary polycrystalline particles, the more concentrated the particle size distribution is, the better. This is because it is difficult for uniform particles to form dense stacking, and the particles will have larger pores. On the one hand, this will increase the macroscopic volume of the powder, which is not conducive to improving the compaction density. On the other hand, when the powder is subjected to pressure, there are fewer contact points between the particles, which easily leads to stress concentration, which is not conducive to improving the compressive resistance of the particles.

[0005] Therefore, controlling the particle size distribution of the precursor material within a wider range is of great significance for the preparation of ternary precursor materials with smaller gaps, high tap density, and relatively higher energy density. At present, it is difficult to change the particle size distribution of the product by adjusting the parameters in the production process, and it is technically difficult. For example, by adjusting the temperature to change the particle size distribution, although the particle size distribution becomes wider, the pH adjustment will be affected and become less sensitive, and the control is not precise, and the surface of the obtained material particles is rough and not smooth. At present, in order to obtain ternary precursor materials with a wide particle size distribution, the relevant technology adopts the method of first obtaining precursor products with different particle size distributions, and then selecting several precursor products according to customer requirements and mixing them in a certain proportion to achieve the particle size distribution requirements. The process operation is very complicated and the cost is high.

[0006] Therefore, how to obtain cathode precursor materials with a wide particle size distribution range is a technical problem that needs to be solved urgently.

[0007] Summary of the Invention

[0008] The following is an overview of the subject matter described in detail in this article. This overview is not intended to limit the scope of protection of the claims.

[0009] Embodiments of this application provide a cathode precursor with a wide particle size distribution, a preparation method thereof, and an application. The cathode precursor material provided by this application has a distance between particle sizes (D90 - D10) / D50 within the range of 0.9 to 2, achieving a wide range of particle size distribution, thereby improving the tap density and compressive properties of the cathode material.

[0010] In a first aspect, embodiments of this application provide a cathode precursor with a wide particle size distribution. The chemical general formula of the cathode precursor is Ni x Co y Mn (1-x-y) R z , where 0 < x ≤ 1, 0 ≤ y < 1, 1 ≤ z ≤ 2; the R includes hydroxide and / or carbonate;

[0011] The cathode precursor with a wide particle size distribution satisfies: 0.9 ≤ (D90 - D10) / D50 ≤ 2.

[0012] For example, x can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1, etc.; y can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9, etc.; z can be 1, 1.5, or 2, etc.

[0013] The (D90 - D10) / D50 can be 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2, etc.

[0014] In this application, within the range of (D90 - D10) / D50 from 0.9 to 2, the larger the value, the wider the particle size distribution.

[0015] The cathode precursor material provided by this application has a distance between particle sizes (D90 - D10) / D50 within the range of 0.9 to 2, achieving a wide range of particle size distribution, and the obtained precursor material has a stable structure, thereby improving the tap density and compressive properties of the cathode material. If (D90 - D10) / D50 is less than 0.9, the effect of wide distribution will become worse, and there is no obvious difference between large and small particles in the finished product, and the effect of improving the tap density and compressive properties cannot be achieved.

[0016] Preferably, the D50 of the positive electrode precursor is 2 to 20 μm, for example, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm.

[0017] In a second aspect, an embodiment of the present application provides a method for preparing a positive electrode precursor with a wide particle size distribution as described in the first aspect, the preparation method comprising the following steps:

[0018] Adding a main metal element mixed salt solution, a precipitant solution, and a complexing agent solution to the bottom liquid in parallel to carry out a co-precipitation reaction, and starting continuous discharge after the reaction reaches the first stage to obtain the positive electrode precursor with a wide particle size distribution;

[0019] Wherein, the main metal element in the main metal element mixed salt solution and Ni x Co y Mn (1-x-y) R z The elements in remain consistent.

[0020] The preparation method provided in the present application performs continuous discharging (i.e., discharging while reacting) after reaching the first stage during the co-precipitation reaction. While continuously discharging, the various parameters of the raw materials added in parallel are only slightly adjusted. This allows for continuous fixation of positive electrode precursor materials with a wide particle size distribution while ensuring sufficient raw materials, which can not only improve production efficiency but also help reduce costs.

[0021] Preferably, the concentration of the main metal element mixed salt solution is 2 to 4 mol / L, for example, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L or 4 mol / L.

[0022] Preferably, the precipitant solution comprises sodium hydroxide solution and / or sodium carbonate solution.

[0023] Preferably, the complexing agent solution comprises any one or a combination of at least two of ammonia solution, oxalic acid solution, sodium oxalate solution, citric acid solution, ammonium bicarbonate solution, lactic acid solution, tartaric acid solution or EDTA solution.

[0024] Preferably, the pH value of the base solution is 7 to 12.3, for example, 7, 7.3, 7.5, 7.8, 8, 8.3, 8.5, 8.8, 9, 9.3, 9.5, 9.8, 10, 10.3, 10.5, 10.8, 11, 11.3, 11.5, 11.8, 12 or 12.3, etc.

[0025] Preferably, the concentration of the complexing agent in the base solution is 0.01 to 0.3 mol / L, for example, 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L or 0.3 mol / L.

[0026] Preferably, the pH value during the coprecipitation reaction is 7 to 13, for example, 7, 7.3, 7.5, 7.8, 8, 8.3, 8.5, 8.8, 9, 9.3, 9.5, 9.8, 10, 10.3, 10.5, 10.8, 11, 11.3, 11.5, 11.8, 12, 12.3, 12.5, 12.8 or 13, etc.

[0027] Preferably, when the positive electrode precursor is a hydroxide, the pH during the coprecipitation reaction is 12 to 13, for example, 12, 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, 12.9 or 13.

[0028] In the present application, when the cathode precursor is hydroxide, if the pH value is too low, it will affect the yield and is not conducive to expanding the diameter distance; and if it is too high, it will cause the D50 to fluctuate too much.

[0029] Preferably, when the positive electrode precursor is a carbonate, the pH value during the coprecipitation reaction is 9 to 9.5, such as 9, 9.1, 9.2, 9.3, 9.4 or 9.5.

[0030] In the present application, when the cathode precursor is carbonate, if the pH value is too low, it will affect the yield and is not conducive to expanding the diameter distance; and if it is too high, it will cause the D50 to fluctuate too much.

[0031] Preferably, the reaction temperature during the coprecipitation reaction is 30-80°C, for example, 30°C, 40°C, 50°C, 60°C, 70°C or 80°C.

[0032] Preferably, the stirring rate during the coprecipitation reaction is 150-450 r / min, for example, 150 r / min, 200 r / min, 250 r / min, 300 r / min, 350 r / min, 400 r / min or 450 r / min.

[0033] Preferably, during the coprecipitation reaction, continuous discharging begins after 30 to 60 hours of reaction, for example, 30 hours, 33 hours, 35 hours, 38 hours, 40 hours, 43 hours, 45 hours, 48 ​​hours, 50 hours, 53 hours, 55 hours, 58 hours or 60 hours.

[0034] In the present application, continuous discharging is carried out after the coprecipitation reaction for at least 30 hours, which can better obtain products with better physical and chemical indicators and sphericity; if the coprecipitation reaction time is too short, and continuous discharging is started before 30 hours, the sphericity of the finished product will be poor; if the reaction time exceeds 60 hours, more waste will be generated, which is not conducive to reducing costs.

[0035] Preferably, during the coprecipitation reaction, reaction seeds are also added in parallel.

[0036] In this application, the reaction seed refers to a small-particle precursor prepared from the same raw materials.

[0037] Preferably, the D50 of the reaction seed crystal is 1 / 3 to 1 / 4 of the D50 of the positive electrode precursor, for example, 1 / 4, 0.28, 0.3, 0.31, 0.32 or 1 / 3.

[0038] In this application, if the particle size of the reaction seed is too large, exceeding 1 / 3 of the D50 of the positive electrode precursor, its addition is not conducive to controlling the particle size of the finished product; and if the particle size of the reaction seed is too small, less than 1 / 4 of the D50 of the positive electrode precursor, the purpose of obtaining a stable finished product particle size cannot be achieved.

[0039] Preferably, during the coprecipitation reaction, when the D50 of the cathode precursor reaches 3 / 5 to 4 / 5 of the target particle size, such as 0.6, 0.65, 0.7, 0.75 or 0.8, reaction seed crystals are added.

[0040] In the present application, during the coprecipitation reaction process, when the D50 of the cathode precursor reaches 3 / 5 to 4 / 5 of the target particle size, reaction seeds are added to better achieve the D50 fluctuation of the finished product within a very small range; and in the subsequent reaction process, the process of adding reaction seeds is synchronously maintained;

[0041] As a preferred technical solution, the preparation method comprises the following steps:

[0042] A main metal element mixed salt solution with a concentration of 2 to 4 mol / L, a precipitant solution, and a complexing agent solution are added to the bottom liquid in parallel, the pH value of the reaction environment is maintained at 7 to 13, and a co-precipitation reaction is carried out at 30 to 80° C. and a stirring rate of 150 to 450 r / min. After the reaction is carried out for 30 to 60 hours, continuous discharge is started to obtain the positive electrode precursor with a wide particle size distribution;

[0043] Wherein, the main metal element in the main metal element mixed salt solution and Ni x Co y Mn (1-x-y) R zThe elements in the coprecipitation reaction are kept consistent; when the positive electrode precursor is a hydroxide, the pH value during the coprecipitation reaction is 12 to 13; when the positive electrode precursor is a carbonate, the pH value during the coprecipitation reaction is 9 to 9.5; during the coprecipitation reaction, when the D50 of the positive electrode precursor reaches 3 / 5 to 4 / 5 of the target particle size, a reaction seed is added, and the D50 of the reaction seed is 1 / 3 to 1 / 4 of the D50 of the positive electrode precursor.

[0044] In a third aspect, an embodiment of the present application provides a positive electrode material, which is obtained by mixing and sintering the positive electrode precursor with a wide particle size distribution as described in the first aspect and a lithium source.

[0045] Preferably, the sintering is performed in an oxygen-containing atmosphere.

[0046] Preferably, the oxygen-containing atmosphere includes an oxygen atmosphere and / or an air atmosphere.

[0047] Preferably, the sintering temperature is 800-1000°C, for example, 800°C, 850°C, 900°C, 950°C or 1000°C.

[0048] Preferably, the sintering time is 12 to 20 hours, for example, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours or 20 hours.

[0049] In a fourth aspect, an embodiment of the present application further provides a lithium-ion battery, wherein the lithium-ion battery comprises the positive electrode material as described in the third aspect.

[0050] Compared with the related art, the embodiments of the present application have the following beneficial effects:

[0051] The positive electrode precursor material provided in the embodiment of the present application achieves a wide range of particle size distribution in the range of 0.9 to 2 by coordinating various parameters in the coprecipitation reaction process, and the obtained precursor material has a stable structure. The positive electrode material obtained from the positive electrode precursor material provided in the present application has a high tap density and excellent compressive performance, and can be used directly without secondary grading.

[0052] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0054] FIG1 is a SEM image of the cathode precursor provided in Example 1;

[0055] FIG2 is a SEM image of the cathode precursor provided in Example 5;

[0056] FIG3 is a SEM image of the positive electrode precursor provided in Comparative Example 1. DETAILED DESCRIPTION

[0057] 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.

[0058] Example 1

[0059] This embodiment provides a positive electrode precursor with a wide particle size distribution. The chemical formula of the positive electrode precursor is Ni 0.9 Co 0.05 Mn 0.05 (OH)2, the D50 of the positive electrode precursor is 4.0 μm, and the diameter distance (D90-D10) / D50 is shown in Table 1;

[0060] The preparation method of the positive electrode precursor is as follows:

[0061] Step 1, nickel sulfate, cobalt sulfate, and manganese sulfate were weighed according to the stoichiometric ratio of Ni:Co:Mn=90:5:5 to prepare a mixed salt solution with a concentration of 2 mol / L;

[0062] Step 2: Sodium hydroxide, ammonia water and water were added to the reactor as the bottom liquid to make the pH value 13.0 and the concentration of ammonia water 0.3 mol / L, and N2 was introduced and the temperature was controlled at 70°C;

[0063] The mixed salt solution, 2 mol / L sodium hydroxide solution and ammonia solution in step 1 are added to the bottom liquid in the reactor in parallel and stirred continuously at a speed of 450 r / min, the pH of the reaction system is maintained at 12.8-13.0, the concentration of ammonia water is 0.3 mol / L, and the material is continuously received after 40 hours of reaction. After washing, drying, sieving and deironing the received material, a spherical precursor with a wide particle size distribution is obtained.

[0064] Example 2

[0065] This embodiment provides a positive electrode precursor with a wide particle size distribution. The chemical formula of the positive electrode precursor is Ni 0.9 Co 0.05 Mn 0.05 (OH)2, the D50 of the positive electrode precursor is 10 μm, and the diameter distance (D90-D10) / D50 is shown in Table 1;

[0066] The preparation method of the positive electrode precursor is as follows:

[0067] Step 1, nickel sulfate, cobalt sulfate, and manganese sulfate were weighed according to the stoichiometric ratio of Ni:Co:Mn=90:5:5 to prepare a mixed salt solution with a concentration of 4 mol / L;

[0068] Step 2: Sodium hydroxide, ammonia water and water were added to the reactor as the bottom liquid to make the pH value 12 and the concentration of ammonia water 0.2 mol / L, and N2 was introduced and the temperature was controlled at 70°C;

[0069] The mixed salt solution in step 1, 2 mol / L sodium hydroxide solution and ammonia solution are added to the bottom liquid in the reactor in parallel and stirred continuously at a speed of 300 r / min, maintaining the pH of the reaction system at 12-12.3 and the concentration of ammonia water at 0.3 mol / L. After 60 hours of reaction, the material is continuously received. After washing, drying, sieving and deironing the received material, a spherical precursor with a wide particle size distribution is obtained.

[0070] Example 3

[0071] This embodiment provides a positive electrode precursor with a wide particle size distribution. The chemical formula of the positive electrode precursor is Ni 0.9 Co 0.05 Mn 0.05 (OH)2, the D50 of the positive electrode precursor is 4.0 μm, and the diameter distance (D90-D10) / D50 is shown in Table 1;

[0072] The difference between this embodiment and embodiment 1 is that in this embodiment, during the coprecipitation reaction in step 2, the pH value is 11.

[0073] The rest of the preparation methods and parameters remained the same as in Example 1.

[0074] Example 4

[0075] This embodiment provides a positive electrode precursor with a wide particle size distribution. The chemical formula of the positive electrode precursor is Ni 0.9 Co 0.05 Mn 0.05 (OH)2, the D50 of the positive electrode precursor is 4.0 μm, and the diameter distance (D90-D10) / D50 is shown in Table 1;

[0076] The difference between this embodiment and embodiment 1 is that in the preparation process of step 2 of this embodiment, after the D50 of the particles inside the reactor reaches 2.4 μm, the reaction seed Ni with a D50 of 1.1 μm is added. 0.9 Co 0.05 Mn 0.05 (OH)2.

[0077] The reaction was continued for 40 hours and then the material was continuously received.

[0078] The rest of the preparation methods and parameters remained the same as in Example 1.

[0079] Example 5

[0080] This embodiment provides a positive electrode precursor with a wide particle size distribution. The chemical formula of the positive electrode precursor is Ni 0.9 Co 0.05 Mn 0.05 (OH)2, the D50 of the positive electrode precursor is 4.0 μm, and the diameter distance (D90-D10) / D50 is shown in Table 1;

[0081] The difference between this embodiment and embodiment 1 is that in the preparation process of step 2 of this embodiment, after the D50 of the particles inside the reactor reaches 3.2 μm, the reaction seed Ni with a D50 of 1.3 μm is added. 0.9 Co 0.05 Mn 0.05 (OH)2.

[0082] The reaction was continued for 40 hours and then the material was continuously received.

[0083] The rest of the preparation methods and parameters remained the same as in Example 1.

[0084] Example 6

[0085] This embodiment provides a positive electrode precursor with a wide particle size distribution. The chemical formula of the positive electrode precursor is Ni 0.9 Co 0.05 Mn 0.05 (OH)2, the D50 of the positive electrode precursor is 4.0 μm, and the diameter distance (D90-D10) / D50 is shown in Table 1;

[0086] The difference between this embodiment and embodiment 1 is that in the preparation process of step 2 of this embodiment, after the D50 of the particles inside the reactor reaches 2.4 μm, the reaction seed Ni with a D50 of 2 μm is added. 0.9 Co 0.05 Mn 0.05 (OH)2.

[0087] The reaction was continued for 40 hours and then the material was continuously received.

[0088] The rest of the preparation methods and parameters remained the same as in Example 1.

[0089] Example 7

[0090] This embodiment provides a positive electrode precursor with a wide particle size distribution. The chemical formula of the positive electrode precursor is Ni 0.9 Co 0.05 Mn 0.05(OH)2, the D50 of the positive electrode precursor is 4.0 μm, and the diameter distance (D90-D10) / D50 is shown in Table 1;

[0091] The difference between this embodiment and embodiment 1 is that in the preparation process of step 2 of this embodiment, after the D50 of the particles inside the reactor reaches 2.4 μm, the reaction seed Ni with a D50 of 0.5 μm is added. 0.9 Co 0.05 Mn 0.05 (OH)2.

[0092] The reaction was continued for 40 hours and then the material was continuously received.

[0093] The rest of the preparation methods and parameters remained the same as in Example 1.

[0094] Example 8

[0095] This embodiment provides a positive electrode precursor with a wide particle size distribution. The chemical formula of the positive electrode precursor is Ni 0.9 Co 0.05 Mn 0.05 CO3, the D50 of the cathode precursor is 4.0 μm, and the diameter distance (D90-D10) / D50 is shown in Table 1;

[0096] The preparation method of the positive electrode precursor is as follows:

[0097] Step 1, nickel sulfate, cobalt sulfate, and manganese sulfate were weighed according to the stoichiometric ratio of Ni:Co:Mn=90:5:5 to prepare a mixed salt solution with a concentration of 2 mol / L;

[0098] Step 2: Sodium carbonate, ammonia water and water were added to the reactor as the bottom liquid to make the pH value of the reactor between 10 and 10.5 and the concentration of ammonia water be 0.3 mol / L. N2 was introduced and the temperature was controlled at 65°C.

[0099] The mixed salt solution, 2 mol / L sodium hydroxide solution and ammonia solution in step 1 were added to the bottom liquid in the reactor in parallel and stirred continuously at a speed of 200 r / min to maintain the pH of the reaction system at 9.3 and the concentration of ammonia water at 0.3 mol / L. After 40 hours of reaction, the material was continuously received. After washing, drying, sieving and deironing the received material, a spherical precursor with a wide particle size distribution was obtained.

[0100] Example 9

[0101] This embodiment provides a positive electrode precursor with a wide particle size distribution. The chemical formula of the positive electrode precursor is Ni 0.9 Co 0.05 Mn 0.05CO3, the D50 of the cathode precursor is 4.0 μm, and the diameter distance (D90-D10) / D50 is shown in Table 1;

[0102] The difference between this embodiment and embodiment 8 is that in step 2 of this embodiment, the pH value during the reaction is 8.

[0103] The remaining preparation methods and parameters remained consistent with those in Example 8.

[0104] Example 10

[0105] This embodiment provides a positive electrode precursor with a wide particle size distribution. The chemical formula of the positive electrode precursor is Ni 0.9 Co 0.05 Mn 0.05 CO3, the D50 of the cathode precursor is 4.0 μm, and the diameter distance (D90-D10) / D50 is shown in Table 1;

[0106] The difference between this embodiment and embodiment 8 is that in step 2 of this embodiment, the pH value during the reaction is 10.

[0107] The remaining preparation methods and parameters remained consistent with those in Example 8.

[0108] Comparative Example 1

[0109] This embodiment provides a positive electrode precursor with a narrow particle size distribution. The chemical formula of the positive electrode precursor is Ni 0.9 Co 0.05 Mn 0.05 (OH)2, the D50 of the positive electrode precursor is 4.0 μm, and the diameter distance (D90-D10) / D50 is shown in Table 1;

[0110] The preparation method of the positive electrode precursor is as follows:

[0111] Step 1, nickel sulfate, cobalt sulfate, and manganese sulfate were weighed according to the stoichiometric ratio of Ni:Co:Mn=90:5:5 to prepare a mixed salt solution with a concentration of 4 mol / L;

[0112] Step 2: Sodium hydroxide, ammonia water and water were added to the reactor as the bottom liquid to make the pH value 12 and the concentration of ammonia water 0.2 mol / L, and N2 was introduced and the temperature was controlled at 70°C;

[0113] The mixed salt solution, 2 mol / L sodium hydroxide solution and ammonia solution in step 1 were added to the bottom liquid in the reactor in parallel and stirred continuously at a speed of 300 r / min, maintaining the pH of the reaction system at 11.0-11.4 and the concentration of ammonia water at 0.3 mol / L. After the reaction for 80 hours, the material in the reactor was washed, dried, sieved and iron removed to obtain a spherical precursor with a wide particle size distribution.

[0114] Comparative Example 2

[0115] This embodiment provides a positive electrode precursor with a narrow particle size distribution. The chemical formula of the positive electrode precursor is Ni 0.9 Co 0.05 Mn 0.05 CO3, the D50 of the cathode precursor is 4.0 μm, and the diameter distance (D90-D10) / D50 is shown in Table 1;

[0116] The preparation method of the positive electrode precursor is as follows:

[0117] Step 1, nickel sulfate, cobalt sulfate, and manganese sulfate were weighed according to the stoichiometric ratio of Ni:Co:Mn=90:5:5 to prepare a mixed salt solution with a concentration of 2 mol / L;

[0118] Step 2: Sodium carbonate, ammonia water and water were added to the reactor as the bottom liquid to make the pH value of the reactor between 10 and 10.5 and the concentration of ammonia water be 0.3 mol / L. N2 was introduced and the temperature was controlled at 65°C.

[0119] The mixed salt solution, 2 mol / L sodium hydroxide solution and ammonia solution in step 1 were added to the bottom liquid in the reactor in parallel and stirred continuously at a speed of 200 r / min to maintain the pH of the reaction system at 7.5 and the concentration of ammonia water at 0.3 mol / L. After the reaction for 80 hours, the material in the reactor was washed, dried, sieved and iron removed to obtain a spherical precursor with a wide particle size distribution.

[0120] Figure 1 shows an SEM image of the positive electrode precursor provided in Example 1; Figure 2 shows an SEM image of the positive electrode precursor provided in Example 5; Figure 3 shows an SEM image of the positive electrode precursor provided in Comparative Example 1; from the comparison of Figures 1-3, it can be seen that by adopting the preparation method provided in the present application, positive electrode precursor particles with a wide particle size distribution are obtained, and the precursor material also maintains good sphericity. At the same time, after adding reaction seeds, the particle size distribution range of the obtained precursor material is wider; thereby, a positive electrode material with a higher tap density is obtained, and the subsequent positive electrode material does not need to be graded again and can be used directly; while by the preparation method provided in Comparative Example 1, precursor particles with a concentrated particle size distribution and uniform size are obtained, which is not conducive to the improvement of the tap density of the positive electrode material.

[0121] Table 1 shows the diameter distance (D90-D10) / D50 provided by Examples 1-10 and Comparative Examples 1-2.

[0122] Table 1

[0123] From Table 1 we can see that:

[0124] From the data results of Example 1 and Example 3, it can be seen that in the hydroxide system, if the pH value during the coprecipitation reaction is too low, the effect of wide distribution will be deteriorated.

[0125] From the data results of Examples 1, 4 and 5, it can be seen that adding reaction seeds during the co-precipitation reaction can further control the distribution of particle size and obtain a particle product with a wide distribution.

[0126] From the data results of Examples 4-7, it can be seen that if the D50 of the reaction seed is too large, it will affect the effect of seed addition and even reduce the diameter distance; if it is too small, it will cause the diameter distance to increase abnormally, causing the particle size distribution to shift to the small particle size side, which in turn reduces the tap density.

[0127] From the data results of Examples 8-10, it can be seen that in the carbonate system, during the coprecipitation reaction, if the pH value is too low, it is difficult to achieve the effect of expanding the diameter distance and thus increasing the tap density.

[0128] From the data results of Example 1 and Comparative Example 1, and Example 8 and Comparative Example 2, it can be seen that the preparation method provided in this application can obtain a positive electrode precursor material with a wide particle size distribution.

[0129] The positive electrode precursor materials provided in Example 1, Example 8 and Comparative Example 1-2 were mixed with LiOH in a molar ratio of 1:1.05, and heated to 800° C. in an oxygen atmosphere, kept at this temperature for 15 h, and then cooled in the furnace to obtain a LiNi 0.9 Co 0.05 Mn 0.05 Spherical cathode material for O2.

[0130] FIG1 shows an SEM image of the positive electrode precursor provided in Example 1. It can be seen from FIG1 that the positive electrode precursor particles obtained by the preparation method provided in the present application are uneven in size and have a wide particle size distribution.

[0131] The positive electrode materials obtained in Example 1, Example 5 and Comparative Example 1 were placed on a tap density meter and tested according to GB-T 21354-2008. The test results are shown in Table 2.

[0132] Table 2

[0133] From Table 2 we can see that:

[0134] From the data results of Example 1, Example 5 and Comparative Example 1, it can be seen that the positive electrode material prepared from the positive electrode precursor material with a wide particle size distribution obtained in the present application has a better tap density and does not require particle grading during use.

[0135] In summary, the positive electrode precursor material provided in the present application achieves a wide range of particle size distribution in the range of 0.9 to 2 by coordinating various parameters in the coprecipitation reaction process, and the obtained precursor material has a stable structure. The positive electrode material obtained from the positive electrode precursor material provided in the present application has a high tap density and excellent compressive performance, and can be used directly without secondary grading.

[0136] The applicant declares that the above is only a specific implementation method of the present application, but the protection scope of the present application is not limited thereto. Technical personnel in the relevant technical field should understand that any changes or substitutions that can be easily thought of by technical personnel in the relevant technical field within the technical scope disclosed in this application fall within the protection scope and disclosure scope of this application.

Claims

1. A positive electrode precursor with a wide particle size distribution, wherein: The chemical general formula of the positive electrode precursor is Ni x Co y Mn (1-x-y) R z , where 0 < x ≤ 1, 0 ≤ y < 1, 1 ≤ z ≤ 2; the R includes hydroxide radical and / or carbonate radical; The positive electrode precursor with a wide particle size distribution satisfies: 0.9≤(D90-D10) / D50≤2.

2. The positive electrode precursor with a wide particle size distribution according to claim 1, wherein The D50 of the positive electrode precursor is 2 to 20 μm.

3. A method for preparing a positive electrode precursor with a wide particle size distribution as claimed in claim 1 or 2, wherein: The preparation method comprises the following steps: Adding a main metal element mixed salt solution, a precipitant solution and a complexing agent solution to the bottom liquid in parallel to carry out a coprecipitation reaction, and starting continuous discharge after the reaction reaches the first stage to obtain the positive electrode precursor with a wide particle size distribution; Wherein, the main metal element in the main metal element mixed salt solution and Ni x Co y Mn (1-x-y) R z The elements in remain consistent.

4. The method for preparing a positive electrode precursor with a wide particle size distribution according to claim 3, wherein: The concentration of the main metal element mixed salt solution is 2-4 mol / L.

5. The method for preparing a positive electrode precursor with a wide particle size distribution according to claim 3 or 4, wherein: The precipitant solution includes sodium hydroxide solution and / or sodium carbonate solution.

6. The method for preparing a positive electrode precursor with a wide particle size distribution according to any one of claims 3 to 5, wherein: The complexing agent solution includes any one of ammonia solution, oxalic acid solution, sodium oxalate solution, citric acid solution, ammonium bicarbonate solution, lactic acid solution, tartaric acid solution or EDTA solution, or a combination of at least two thereof.

7. The method for preparing a positive electrode precursor with a wide particle size distribution according to any one of claims 3 to 6, wherein: The pH value of the base solution is 7 to 12.3; Preferably, the concentration of the complexing agent in the base solution is 0.01 to 0.3 mol / L; Preferably, the pH value during the coprecipitation reaction is 7 to 13; Preferably, when the cathode precursor is a hydroxide, the pH during the coprecipitation reaction is 12 to 13; Preferably, when the cathode precursor is a carbonate, the pH value during the coprecipitation reaction is 9 to 9.5; Preferably, the reaction temperature during the coprecipitation reaction is 30 to 80°C; Preferably, the stirring rate during the coprecipitation reaction is 150-450 r / min.

8. The method for preparing a positive electrode precursor with a wide particle size distribution according to any one of claims 3 to 7, wherein: During the coprecipitation reaction, continuous discharging begins after 30 to 60 hours of reaction. Preferably, during the coprecipitation reaction, reaction seeds are also added in parallel; Preferably, the D50 of the reaction seed is 1 / 3 to 1 / 4 of the D50 of the positive electrode precursor; Preferably, during the coprecipitation reaction, when the D50 of the positive electrode precursor reaches 3 / 5 to 4 / 5 of the target particle size, reaction seeds are added.

9. The method for preparing a positive electrode precursor with a wide particle size distribution according to any one of claims 3 to 8, comprising the following steps: A main metal element mixed salt solution with a concentration of 2 to 4 mol / L, a precipitant solution and a complexing agent solution are added to the bottom liquid in parallel, the pH value in the reaction environment is maintained at 7 to 13, a coprecipitation reaction is carried out at 30 to 80° C. and a stirring rate of 150 to 450 r / min, and continuous discharge is started after the reaction for 30 to 60 hours to obtain the positive electrode precursor with a wide particle size distribution; Wherein, the main metal element in the main metal element mixed salt solution and Ni x Co y Mn (1-x-y) R z The elements in the reaction mixture remain consistent; when the cathode precursor is a hydroxide, the pH value during the coprecipitation reaction is 12 to 13; when the cathode precursor is a carbonate, the pH value during the coprecipitation reaction is 9 to 9.5; during the coprecipitation reaction, when the D50 of the cathode precursor reaches 3 / 5 to 4 / 5 of the target particle size, a reaction seed is added, and the D50 of the reaction seed is 1 / 3 to 1 / 4 of the D50 of the cathode precursor.

10. A positive electrode material, wherein: The positive electrode material is obtained by mixing and sintering the positive electrode precursor with a wide particle size distribution as claimed in claim 1 or 2 and a lithium source.

11. The positive electrode material according to claim 10, wherein The sintering is performed in an oxygen-containing atmosphere.

12. The positive electrode material according to claim 11, wherein The oxygen-containing atmosphere includes an oxygen atmosphere and / or an air atmosphere.

13. The positive electrode material according to any one of claims 10 to 12, wherein: The sintering temperature is 800-1000°C; Preferably, the sintering time is 12 to 20 hours.

14. A lithium ion battery, characterized in that: The lithium-ion battery comprises the positive electrode material according to any one of claims 10 to 13.

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