A ternary precursor, a preparation method and application thereof

Abstract

The application discloses a ternary precursor and a preparation method and application thereof. The preparation method comprises the following steps: 1) nucleation: metal salt solution, ammonia water and lye are introduced into a reactor to perform a nucleation reaction, a protective gas is introduced in the early stage of the nucleation reaction, and a mixed oxygenation gas is introduced in the middle and late stages of the nucleation reaction; 2) growth: after nucleation, the reaction is continuously performed to grow, a protective gas is introduced in the early stage of the growth, a strong mixed oxygenation gas is introduced in the middle stage of the growth, a protective gas is introduced in the late stage of the growth, the feeding is stopped when the growth reaches a preset particle size, the reaction is ended, and the ternary precursor is obtained. The ternary precursor with good sphericity and high tap density and small particles is prepared by controlling the reaction gas atmosphere in the preparation stage, the dispersity of the particles is good, the preparation method is simple, the reaction repeatability is high, and the method is very convenient for industrialization.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a ternary precursor, its preparation method, and its application. Background Technology

[0002] With the rapid development of the global automotive industry, new energy vehicles have become the industry's development direction. Since new energy vehicles rely on lithium-ion batteries as their core power source, improving the energy density, cycle performance, and safety performance of lithium-ion batteries has become a key research focus.

[0003] Ternary lithium batteries are characterized by high energy density. They are mainly composed of a positive electrode, a negative electrode, and an electrolyte. The active material in the positive electrode is a ternary positive electrode material. The preparation of ternary positive electrode material requires the co-sintering of lithium salt and ternary precursor. The performance of the ternary precursor greatly affects the performance of the ternary lithium battery.

[0004] The tap density of ternary precursors significantly affects the volumetric energy density of cathode materials; a higher tap density results in a higher volumetric energy density. The sphericity of ternary precursors also influences the cycle performance of cathode materials, and an increasing number of international manufacturers are demanding better sphericity from ternary precursors.

[0005] Ternary precursors with a high manganese content exhibit good cycling performance, but their uniformity during preparation is often poor, and particles tend to agglomerate. CN2019113245696.2 obtained a high-tap, large-particle precursor by changing the pH at different growth stages; however, this requires adjusting the overflow valve and reaction pH based on the current particle size, making the reaction difficult to control. Significant pH changes can also destabilize the system, hindering industrialization.

[0006] CN201911324804.6 describes the preparation of a ternary precursor with high tap density by adding sodium borate, but the reaction uniformity needs further investigation.

[0007] CN202111027376.8 describes the preparation of a ternary precursor with high tap density by adding seed crystals. This adds an extra seed crystal preparation process to the precursor preparation process, and increases the number of crystal reaction vessels, making the reaction process and equipment more complex.

[0008] Therefore, it is necessary to provide a simple preparation method for ternary precursors that ensures good dispersibility, good sphericity, and high tap density. Summary of the Invention

[0009] To address the aforementioned problems in existing technologies, the present invention aims to provide a ternary precursor, its preparation method, and its applications. By controlling the reaction gas atmosphere in five stages (early nucleation reaction, middle and late nucleation reaction, early growth, middle growth, and late growth), the present invention prepares small-particle ternary precursors with good sphericity and high tap density. The particles exhibit good dispersibility, and the preparation method is simple, with high reaction repeatability, making it highly suitable for industrialization.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] In a first aspect, the present invention provides a method for preparing a ternary precursor, the method comprising the following steps:

[0012] (1) Nucleation:

[0013] Metal salt solution, ammonia water and alkaline solution are introduced into the reactor to carry out nucleation reaction. Protective gas is introduced in the early stage of nucleation reaction, and mixed gas of medium oxidation is introduced in the middle and late stages of nucleation reaction.

[0014] (2) Growth:

[0015] After nucleation, the reaction continues to grow. A protective gas is introduced in the early stage of growth, a strong oxidizing mixed gas is introduced in the middle stage of growth, and a protective gas is introduced in the later stage of growth. Once the preset particle size is reached, the reaction ends to obtain the ternary precursor.

[0016] This invention prepares small-particle ternary precursors with good sphericity and high tap density by controlling the reaction gas atmosphere in five stages (early stage of nucleation reaction, middle and late stage of nucleation reaction, early stage of growth, middle stage of growth and late stage of growth). The particles have good uniformity, and the preparation method is simple, with high reaction repeatability, making it very convenient for industrialization.

[0017] The method of the present invention does not require the addition of seed crystals or forced changes in reaction pH, which are complex operations that can easily lead to system instability. It does not require the addition of additives. It only requires controlling the reaction gas atmosphere at each stage and slowly lowering the pH during the preparation process to create a more stable reaction system, thereby preparing a ternary precursor with high tap density, good sphericity, and good dispersibility.

[0018] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0019] Preferably, the metal salt solution is prepared according to the chemical formula of the ternary precursor, wherein the chemical formula of the ternary precursor is Ni. x Co y Mn z(OH)₂, where x + y + z = 1, 0.5 < x < 0.7, 0 < y < 0.1, 0.3 < z < 0.7. Here, x can be, for example, 0.55, 0.58, 0.6, 0.62, 0.65, or 0.68; y can be, for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, or 0.09; and z can be, for example, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, or 0.68.

[0020] Preferably, the concentration of the metal salt solution is 1 mol / L to 3 mol / L, for example, it can be 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L or 3 mol / L, etc.

[0021] Preferably, the flow rate of the metal salt solution is 2L / h-6L / h, for example, it can be 2L / h, 2.5L / h, 3L / h, 3.5L / h, 4L / h, 4.5L / h, 5L / h, 5.5L / h or 6L / h, etc.

[0022] Preferably, the mass fraction of the ammonia water is 10%-20%, for example, it can be 10%, 12%, 14%, 15%, 17%, 18% or 20%, etc.

[0023] Preferably, the mass fraction of the alkaline solution is 10%-40%, such as 10%, 12%, 13%, 14%, 15%, 20%, 23%, 26%, 30%, 33%, 37%, or 40%.

[0024] Preferably, during the nucleation reaction and the growth process, the ammonia content is in the range of 3 g / L to 8 g / L. For example, the ammonia content can be 3 g / L, 3.5 g / L, 4 g / L, 4.5 g / L, 5 g / L, 5.5 g / L, 6 g / L, 6.5 g / L, 7 g / L, 7.5 g / L, or 8 g / L. The ammonia content can be the same or different during the nucleation reaction and the growth process, but it is preferred to be the same.

[0025] Preferably, during the nucleation reaction and the growth process, the reaction temperature is within the range of 40℃-70℃, and the reaction temperature can be, for example, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, or 70℃. The reaction temperature can be the same or different during the nucleation reaction and the growth process, but it is preferred to be the same.

[0026] As a preferred technical solution of the preparation method of the ternary precursor of the present invention, the pH of the reaction in the early stage of the nucleation reaction is 12.0-12.6, for example, it can be 12.0, 12.1, 12.2, 12.4, 12.5 or 12.6.

[0027] Preferably, the reaction time in the early stage of the nucleation reaction is 2h-8h, for example, it can be 2h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h or 8h.

[0028] Preferably, in the early stage of the nucleation reaction, the protective gas introduced includes any one or a mixture of at least two of nitrogen, helium, argon, neon and krypton.

[0029] Preferably, in the early stage of the nucleation reaction, the flow rate of the protective gas is 2L / min-10L / min, for example, it can be 2L / min, 3L / min, 3.5L / min, 4L / min, 5L / min, 6L / min, 7L / min, 7.5L / min, 8L / min, 9L / min or 10L / min, etc.

[0030] Preferably, after the initial stage of the nucleation reaction, the particle size D50 of the formed reaction nuclei is 1.3μm-2μm, for example, it can be 1.3μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm or 2μm, etc.

[0031] In the middle and later stages of the nucleation reaction, the pH of the reaction is 12.0-11.5, for example, it can be 12.0, 11.8, 11.7, 11.6 or 11.5, etc.

[0032] Preferably, the reaction time in the middle and late stages of the nucleation reaction is 2h-10h, for example, it can be 2h, 3h, 4h, 4.5h, 5h, 6h, 7h, 8h, 9h or 10h.

[0033] Preferably, in the middle and later stages of the nucleation reaction, the particle size D50 of the nuclei to be reacted is 1.6 μm-3 μm (e.g., 1.6 μm, 1.7 μm, 1.8 μm, 2 μm, 2.2 μm, 2.5 μm, 2.7 μm, or 3 μm, etc.), and a medium-oxidizing mixed gas is introduced. It should be noted that the introduction of the protective gas should be stopped simultaneously with the introduction of the medium-oxidizing mixed gas.

[0034] Preferably, in the middle and later stages of the nucleation reaction, the intermediate oxidation mixed gas introduced includes a mixture of an inert gas and air, wherein the air content in the mixed gas is 20 vol%-35 vol%, for example, it can be 20 vol%, 22 vol%, 24 vol%, 25 vol%, 28 vol%, 30 vol%, or 33 vol%.

[0035] Preferably, the inert gas includes at least one of nitrogen, helium, argon, neon, and krypton.

[0036] Preferably, in the middle and later stages of the nucleation reaction, the flow rate of the intermediate oxidation mixed gas is 2L / min-10L / min, for example, it can be 2L / min, 3L / min, 3.5L / min, 4L / min, 5L / min, 6L / min, 7L / min, 8L / min, 9L / min or 10L / min, etc.

[0037] As a preferred technical solution of the preparation method of the ternary precursor of the present invention, in the initial stage of growth, the pH of the reaction is 11.5-11.0, such as 11.5, 11.3, 11.2 or 11.0.

[0038] Preferably, the reaction time in the initial stage of growth is 4h-13h, such as 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h or 13h.

[0039] Preferably, during the initial stage of growth, when the particle size D50 of the ternary precursor is 2.4 μm-4 μm (e.g., 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 3 μm, 3.2 μm, 3.3 μm, 3.5 μm, 3.6 μm, 3.7 μm, 3.8 μm, or 4 μm, etc.), a protective gas is introduced. It should be noted that the introduction of the neutralizing mixed gas should be stopped simultaneously with the introduction of the protective gas.

[0040] Preferably, in the initial stage of growth, the protective gas introduced includes at least one of nitrogen, helium, argon, neon, and krypton.

[0041] Preferably, during the initial stage of growth, the flow rate of the protective gas is 2L / min-10L / min, for example, it can be 2L / min, 3L / min, 3.5L / min, 4L / min, 5L / min, 6L / min, 7L / min, 8L / min, 9L / min or 10L / min, etc.

[0042] During the middle stage of growth, the pH of the reaction is 10.5-11.0, for example, it can be 10.5, 10.6, 10.8, 10.9 or 11.0, etc.

[0043] Preferably, during the middle stage of growth, when the particle size D50 of the ternary precursor reaches 3.2 μm-5 μm (e.g., 3.2 μm, 3.3 μm, 3.5 μm, 3.6 μm, 3.8 μm, 4 μm, 4.3 μm, 4.4 μm, 4.6 μm, 4.8 μm, or 5 μm, etc.), a strong oxidizing mixed gas is introduced. It should be noted that the introduction of the protective gas should be stopped simultaneously with the introduction of the strong oxidizing mixed gas.

[0044] Preferably, during the middle stage of growth, the introduced strong oxidizing mixed gas comprises a mixture of an inert gas and air;

[0045] Preferably, in the strong oxidizing mixed gas, the inert gas includes at least one of nitrogen, helium, argon, neon, and krypton.

[0046] Preferably, the air content in the strong oxidizing mixture is 45 vol% to 80 vol%, for example, it can be 45 vol%, 50 vol%, 55 vol%, 60 vol%, 65 vol%, 70 vol%, 75 vol%, or 80 vol%.

[0047] Preferably, during the middle stage of growth, the flow rate of the strongly oxidizing mixed gas is 2L / min-10L / min, for example, it can be 2L / min, 3L / min, 3.5L / min, 4L / min, 5L / min, 6L / min, 7L / min, 8L / min, 9L / min or 10L / min, etc.

[0048] Preferably, in the later stage of growth, the pH of the reaction is 10.5-11.0, for example, it can be 10.5, 10.6, 10.7, 10.8, 10.9 or 11.0.

[0049] Preferably, in the later stage of growth, when the particle size D50 of the ternary precursor is 4.5-4.9 μm, a protective gas is introduced.

[0050] Preferably, in the later stage of growth, the protective gas introduced includes any one or a mixture of at least two of nitrogen, helium, argon, neon and krypton.

[0051] Preferably, in the later stage of growth, the flow rate of the protective gas is 2L / min-10L / min, for example, it can be 2L / min, 3L / min, 3.5L / min, 4L / min, 5L / min, 6L / min, 7L / min, 8L / min, 9L / min or 10L / min, etc.

[0052] It should be noted that during the later stages of growth, while introducing protective gas, the introduction of strong oxidizing mixed gas should be stopped.

[0053] In a second aspect, the present invention provides a ternary precursor prepared by the preparation method described in the first aspect.

[0054] Thirdly, the present invention provides a ternary cathode material, which is prepared from the ternary precursor described in the second aspect.

[0055] Fourthly, the present invention provides a battery comprising the ternary cathode material described in the third aspect.

[0056] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0057] Compared with existing technologies, the present invention has the following beneficial effects:

[0058] (1) This invention prepares small-particle ternary precursors with good sphericity and high tap density by controlling the reaction gas atmosphere in five stages (early stage of nucleation reaction, middle and late stage of nucleation reaction, early stage of growth, middle stage of growth, and late stage of growth). The particles have good uniformity, and the sphericity of the ternary precursors can reach above 0.835, and the tap density can reach 1.99 g / cm³. 3 above.

[0059] (2) The preparation method of the present invention is simple, the reaction is highly reproducible, and it is very easy to industrialize. Detailed Implementation

[0060] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0061] Example 1

[0062] This embodiment provides a method for preparing a ternary precursor, including the following steps:

[0063] Step 1: Based on the molecular formula Ni 0.60 Co 0.07 Mn 0.33 Prepare a 3 mol / L metal salt solution (where Ni is derived from nickel nitrate, Co from cobalt nitrate, and Mn from manganese nitrate) with (OH)2; prepare 18% ammonia water and 27% alkali solution (NaOH solution); control the reaction temperature at 65℃, the flow rate of the metal salt solution at 5 L / h, the ammonia content of the reaction system at 7 g / L, control the pH of the reaction system within the range of 12.3-12.2, react for 6 h, and introduce nitrogen gas at a flow rate of 6 L / min during the early stage of nucleation to obtain reaction nuclei with a particle size D50 of 1.4 μm.

[0064] Step 2: During the mid-to-late nucleation stage, control the pH within the range of 12.0-11.8 and react for 5 hours. When the particle size reaches 1.6 μm, stop the nitrogen gas supply and introduce a mixed gas for oxidation (composed of nitrogen and air, with air accounting for 25 vol%) at a flow rate of 6 L / min.

[0065] Step 3: In the early stage of growth, control the pH at 11.5-11.3 and react for 12 hours. When the particle size reaches 2.4 μm, stop the introduction of the mixed gas of oxidation and introduce nitrogen gas at a flow rate of 6 L / min.

[0066] Step 4: During the mid-growth stage, control the pH at 10.7-10.5. When the particle size reaches 3.2μm, stop the nitrogen gas supply and introduce a strong oxidizing mixed gas (composed of nitrogen and air, with air accounting for 60 vol%) at a flow rate of 6 L / min.

[0067] Step 5: In the later stage of growth, control the pH at 10.7-10.5. When the particle size reaches 4.5μm, stop the introduction of strong oxidizing mixed gas and introduce nitrogen gas at a flow rate of 6L / min. When the reaction reaches the target particle size of 5μm, stop feeding, filter, wash and dry to obtain the ternary precursor.

[0068] Example 2

[0069] This embodiment provides a method for preparing a ternary precursor, including the following steps:

[0070] Step 1: Based on the molecular formula Ni 0.80 Co 0.10 Mn 0.10 Prepare a 2 mol / L metal salt solution (where Ni is derived from nickel nitrate, Co from cobalt nitrate, and Mn from manganese nitrate) with (OH)2; prepare a 15% (w / w) ammonia solution and a 35% (w / w) alkaline solution (NaOH solution); control the reaction temperature at 65℃, the flow rate of the metal salt solution at 3 L / h, the ammonia content of the reaction system at 8 g / L, control the pH of the reaction system within the range of 12.4-12.3, react for 8 h, and introduce helium gas at a flow rate of 2 L / min during the early stage of nucleation to obtain reaction nuclei with a particle size D50 of 1.5 μm.

[0071] Step 2: In the mid-to-late stage of nucleation, control the pH in the range of 12.1-11.9 and react for 6 hours. When the particle size reaches 1.8 μm, stop the helium gas supply and introduce a mixed gas of helium and air (35 vol%) at a flow rate of 8 L / min.

[0072] Step 3: In the early stage of growth, control the pH at 11.6-11.4 and react for 6 hours. When the particle size reaches 2.3 μm, stop the introduction of the mixed gas of oxidation and introduce nitrogen gas at a flow rate of 6 L / min.

[0073] Step 4: During the mid-growth stage, control the pH at 10.8-10.6. When the particle size reaches 4μm, stop the nitrogen gas supply and introduce a strong oxidizing mixed gas (composed of nitrogen and air, with air accounting for 80 vol%) at a flow rate of 7 L / min.

[0074] Step 5: In the later stage of growth, control the pH at 10.7-10.5. When the particle size reaches 4.5μm, stop the introduction of strong oxidizing mixed gas and introduce nitrogen gas at a flow rate of 6L / min. When the reaction reaches the target particle size of 5μm, stop feeding, filter, wash and dry to obtain the ternary precursor.

[0075] Example 3

[0076] This embodiment provides a method for preparing a ternary precursor, including the following steps:

[0077] Step 1: Based on the molecular formula Ni 0.70 Co 0.07 Mn 0.23 Prepare a 1 mol / L metal salt solution (where Ni is derived from nickel nitrate, Co from cobalt chloride, and Mn from manganese chloride) with (OH)2; prepare a 16% (w / w) ammonia solution and a 20% (w / w) alkaline solution (NaOH solution); control the reaction temperature at 65℃, the flow rate of the metal salt solution at 4 L / h, the ammonia content of the reaction system at 4 g / L, control the pH of the reaction system within the range of 12.5-12.4, react for 3 h, and introduce nitrogen gas at a flow rate of 2 L / min during the early stage of nucleation to obtain reaction nuclei with a particle size D50 of 1.3 μm.

[0078] Step 2: During the mid-to-late nucleation stage, control the pH within the range of 12.2-11.9 and react for 8 hours. When the particle size reaches 1.7 μm, stop the nitrogen gas supply and introduce a mixed gas of nitrogen and air (30 vol%) at a flow rate of 5 L / min.

[0079] Step 3: In the early stage of growth, control the pH at 11.7-11.5 and react for 10 hours. When the particle size reaches 2.4 μm, stop the introduction of the mixed gas of oxidation and introduce helium at a flow rate of 6 L / min.

[0080] Step 4: During the mid-growth stage, control the pH at 10.9-10.6. When the particle size reaches 4.3μm, stop the nitrogen gas supply and introduce a strong oxidizing mixed gas (composed of helium and air, with air accounting for 47 vol%) at a flow rate of 6 L / min.

[0081] Step 5: In the later stage of growth, control the pH at 10.7-10.5. When the particle size reaches 4.7μm, stop the introduction of strong oxidizing mixed gas and introduce helium at a flow rate of 10L / min. When the reaction reaches the target particle size of 5.5μm, stop feeding, filter, wash, and dry to obtain the ternary precursor.

[0082] Example 4

[0083] This embodiment provides a method for preparing a ternary precursor, including the following steps:

[0084] Step 1: Based on the molecular formula Ni 0.60 Co 0.07 Mn 0.33 A 2.5 mol / L metal salt solution was prepared using (OH)₂ (where Ni was derived from nickel sulfate, Co from cobalt sulfate, and Mn from manganese sulfate); a 13% (w / w) ammonia solution and a 15% (w / w) alkaline solution (NaOH solution) were prepared. The reaction temperature was controlled at 65℃, the flow rate of the metal salt solution was 2 L / h, the ammonia content of the reaction system was 6 g / L, and the pH of the reaction system was controlled within the range of 12.3-12.2. The reaction was carried out for 7 h, and nitrogen gas was introduced during the early stage of nucleation at a flow rate of 9 L / min to obtain reaction nuclei with a particle size D50 of 1.45 μm.

[0085] Step 2: During the mid-to-late nucleation stage, control the pH within the range of 12.0-11.7 and react for 3 hours. When the particle size reaches 1.6 μm, stop the nitrogen gas supply and introduce a mixed gas for oxidation (composed of nitrogen and air, with air accounting for 20 vol%) at a flow rate of 6 L / min.

[0086] Step 3: In the early stage of growth, control the pH at 11.5-11.3 and react for 8 hours. When the particle size reaches 2.2 μm, stop the introduction of the mixed gas of oxidation and introduce nitrogen gas at a flow rate of 6 L / min.

[0087] Step 4: During the mid-growth stage, control the pH at 10.9-10.7. When the particle size reaches 4.5μm, stop the nitrogen gas supply and introduce a strong oxidizing mixed gas (composed of nitrogen and air, with air accounting for 55 vol%) at a flow rate of 10 L / min.

[0088] Step 5: In the later stage of growth, control the pH at 10.6-10.5. When the particle size reaches 4.8μm, stop the introduction of strong oxidizing mixed gas and introduce nitrogen gas at a flow rate of 9L / min. When the reaction reaches the target particle size of 6μm, stop feeding, filter, wash and dry to obtain the ternary precursor.

[0089] Example 5

[0090] This embodiment provides a method for preparing a ternary precursor, which differs from Embodiment 1 only in that, in step 2, the air content in the oxidizing mixed gas is 18 vol%.

[0091] Example 6

[0092] This embodiment provides a method for preparing a ternary precursor, which differs from Embodiment 1 only in that, in step 2, the air content in the oxidizing mixed gas is 37 vol%.

[0093] Example 7

[0094] This embodiment provides a method for preparing a ternary precursor, which differs from Embodiment 1 only in that, in step 4, the air content in the strongly oxidizing mixed gas is 42 vol%.

[0095] Example 8

[0096] This embodiment provides a method for preparing a ternary precursor, which differs from Embodiment 1 only in that, in step 4, the air content in the strongly oxidizing mixed gas is 82 vol%.

[0097] Comparative Example 1

[0098] This embodiment provides a method for preparing a ternary precursor, which differs from Embodiment 1 only in that the gas introduced throughout the preparation process is nitrogen.

[0099] Comparative Example 2

[0100] This embodiment provides a method for preparing a ternary precursor. The only difference from Embodiment 1 is that the nitrogen in step 1 is replaced with a medium-oxidation mixed gas (composed of nitrogen and air, with air accounting for 25 vol%), so that the atmosphere throughout the nucleation stage is a medium-oxidation mixed gas.

[0101] Comparative Example 3

[0102] This embodiment provides a method for preparing a ternary precursor. The only difference from Embodiment 1 is that the oxidizing mixed gas in step 2 is replaced with nitrogen, so that the atmosphere throughout the nucleation stage is nitrogen gas.

[0103] Comparative Example 4

[0104] This embodiment provides a method for preparing a ternary precursor. The only difference from Embodiment 1 is that the strong oxidizing mixed gas in step 4 is replaced with nitrogen, so that the entire growth stage is in a nitrogen atmosphere.

[0105] Comparative Example 5

[0106] This embodiment provides a method for preparing a ternary precursor. The only difference from Embodiment 1 is that the nitrogen in step 5 is replaced with a strong oxidizing mixed gas. The atmosphere control during the growth stage is as follows: nitrogen atmosphere during the initial growth stage, and strong oxidizing mixed gas during the middle and later growth stages.

[0107] test:

[0108] (1) Dispersion test: The fineness index (SPAN) is obtained by laser particle size analyzer. The closer the SPAN is to 0, the better the dispersion. The closer the SPAN is to 1, the worse the dispersion.

[0109] (2) Tap density (TD) test: Performed in accordance with GB / T 6750-2008.

[0110] (3) Sphericity test: Performed in accordance with section 5.4 of GB / T 39251-2020. The sphericity value is obtained by dynamic particle image analysis. The closer the sphericity is to 1, the better the sphericity.

[0111] The test results are shown in Table 1.

[0112] Table 1

[0113]

[0114]

[0115] As shown in Table 1, the ternary precursor prepared by controlling the reaction gas atmosphere in five stages (early stage of nucleation reaction, middle and late stage of nucleation reaction, early stage of growth, middle stage of growth, and late stage of growth) using the method of this invention exhibits good dispersibility, good sphericity, and high tap density. In contrast, the atmosphere control in Comparative Examples 1-5 was unsuitable, failing to achieve both good sphericity and high tap density.

[0116] A comparison of Examples 1 and 5-6 shows that the preferred air content in the oxidizing mixed gas is 20 vol%-35 vol%. If the air content is too low, it will lead to reduced dispersibility and poor sphericity; if the air content is too high, it will lead to excessively rapid growth, loose structure, and reduced tap density.

[0117] By comparing Example 1 with Comparative Examples 7-8, it can be seen that the air content in the strong oxidizing mixed gas has a preferred range of 45 vol%-80 vol%. If the air content is too low, it will result in the inability to form a primary precursor with fine and dense grains, thus reducing the tap density. If the air content is too high, it will result in excessively rapid particle growth and particle adhesion, which will reduce the dispersibility and sphericity, thereby reducing the tap density.

[0118] The applicant declares that the detailed method of the present invention is illustrated by the above embodiments, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a ternary precursor, characterized in that, The preparation method includes the following steps: (1) Nucleation: Metal salt solution, ammonia water and alkaline solution are introduced into the reactor to carry out nucleation reaction. Protective gas is introduced in the early stage of nucleation reaction, and mixed gas of medium oxidation is introduced in the middle and late stages of nucleation reaction. After the initial stage of the nucleation reaction, the particle size D50 of the formed reaction nuclei is 1.3 μm-2 μm; In the middle and late stages of the nucleation reaction, when the particle size D50 of the nuclei to be reacted is 1.6μm-3μm, the protective gas is stopped and a medium-oxidation mixed gas is introduced. The intermediate oxidation mixed gas comprises a mixture of an inert gas and air, wherein the air content in the intermediate oxidation mixed gas is 20 vol%-35 vol%. (2) Growth: After nucleation, the reaction continues to grow. A protective gas is introduced in the early stage of growth, a strong oxidizing mixed gas is introduced in the middle stage of growth, and a protective gas is introduced in the later stage of growth. When the growth reaches the preset particle size, the feeding is stopped, the reaction is ended, and a ternary precursor is obtained. In the initial stage of growth, when the particle size D50 of the ternary precursor is 2.4μm-4μm, the introduction of the intermediate oxidation mixed gas is stopped, and a protective gas is introduced. During the middle stage of growth, when the particle size D50 of the ternary precursor is 3.2μm-4.6μm, the protective gas is stopped and a strong oxidizing mixed gas is introduced. In the later stage of growth, when the particle size D50 of the ternary precursor is 4.5-4.9 μm, the strong oxidizing mixed gas is stopped and a protective gas is introduced. The strong oxidizing gas mixture comprises a mixture of an inert gas and air, wherein the air content in the strong oxidizing gas mixture is 45 vol%-80 vol%.

2. The method for preparing the ternary precursor according to claim 1, characterized in that, The metal salt solution is prepared according to the chemical formula of the ternary precursor, which is Ni. x Co y Mn z (OH)2, where x+y+z=1, 0.5<x<0.7, 0<y<0.1, 0.3<z<0.

7.

3. The method for preparing the ternary precursor according to claim 1, characterized in that, The concentration of the metal salt solution is 1 mol / L to 3 mol / L.

4. The method for preparing the ternary precursor according to claim 1, characterized in that, The flow rate of the metal salt solution is 2L / h-6L / h.

5. The method for preparing the ternary precursor according to claim 1, characterized in that, The mass fraction of the ammonia water is 10%-20%.

6. The method for preparing the ternary precursor according to claim 1, characterized in that, The mass fraction of the alkaline solution is 10%-40%.

7. The method for preparing the ternary precursor according to claim 1, characterized in that, During the nucleation reaction and the growth process, the ammonia content is in the range of 3 g / L to 8 g / L.

8. The method for preparing the ternary precursor according to claim 1, characterized in that, During the nucleation reaction and the growth process, the reaction temperature is in the range of 40℃-70℃.

9. The method for preparing the ternary precursor according to claim 1, characterized in that, In the early stage of the nucleation reaction, the pH of the reaction is 12.0-12.

6.

10. The method for preparing the ternary precursor according to claim 1, characterized in that, The initial stage of the nucleation reaction lasts for 2-8 hours.

11. The method for preparing the ternary precursor according to claim 1, characterized in that, In the early stage of the nucleation reaction, the protective gas introduced includes any one or a mixture of at least two of the following gases: nitrogen, helium, argon, neon, and krypton.

12. The method for preparing the ternary precursor according to claim 1, characterized in that, In the early stage of the nucleation reaction, the flow rate of the protective gas is 2 L / min-10 L / min.

13. The method for preparing the ternary precursor according to claim 1, characterized in that, In the middle and later stages of the nucleation reaction, the pH of the reaction is 12.0-11.

5.

14. The method for preparing the ternary precursor according to claim 1, characterized in that, The nucleation reaction takes 2-10 hours to complete in the middle and later stages.

15. The method for preparing the ternary precursor according to claim 1, characterized in that, The inert gas includes at least one of nitrogen, helium, argon, neon, and krypton.

16. The method for preparing the ternary precursor according to claim 1, characterized in that, During the middle and later stages of the nucleation reaction, the flow rate of the intermediate oxidation mixed gas is 2 L / min-10 L / min.

17. The method for preparing the ternary precursor according to claim 1, characterized in that, In the initial stage of growth, the pH of the reaction is 11.5-11.

0.

18. The method for preparing the ternary precursor according to claim 1, characterized in that, In the initial stage of growth, the reaction time is 4-13 hours.

19. The method for preparing the ternary precursor according to claim 1, characterized in that, During the initial stage of growth, the protective gas introduced includes at least one of nitrogen, helium, argon, neon, and krypton.

20. The method for preparing the ternary precursor according to claim 1, characterized in that, During the initial stage of growth, the flow rate of the protective gas is 2 L / min to 10 L / min.

21. The method for preparing the ternary precursor according to claim 1, characterized in that, During the middle stage of growth, the pH of the reaction is 10.5-11.

0.

22. The method for preparing the ternary precursor according to claim 1, characterized in that, In the strongly oxidizing mixed gas, the inert gas includes at least one of nitrogen, helium, argon, neon, and krypton.

23. The method for preparing the ternary precursor according to claim 1, characterized in that, During the middle stage of growth, the flow rate of the strongly oxidizing mixed gas is 2 L / min-10 L / min.

24. The method for preparing the ternary precursor according to claim 1, characterized in that, During the later stages of growth, the pH of the reaction is 10.5-11.

0.

25. The method for preparing the ternary precursor according to claim 1, characterized in that, During the later stages of growth, the protective gas introduced includes any one or a mixture of at least two of the following gases: nitrogen, helium, argon, neon, and krypton.

26. The method for preparing the ternary precursor according to claim 1, characterized in that, During the later stages of growth, the flow rate of the protective gas is 2 L / min to 10 L / min.

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