Preparation method of zirconium-doped ternary precursor

Abstract

The invention relates to a preparation method of a zirconium-doped ternary precursor, and the preparation method comprises the following steps: a nucleation stage: adding a ternary metal salt solution, a first zirconium salt solution, a precipitator solution and a complexing agent solution into a base solution in a parallel flow manner, and carrying out a first reaction to obtain a first reaction solution; in the growth stage, a ternary metal salt solution, a second zirconium salt solution, a precipitator solution and a complexing agent solution are added into the first reaction solution in a parallel flow mode, a second reaction solution is obtained through a second reaction, and then the zirconium-doped ternary precursor is obtained through solid-liquid separation; wherein the temperature of the second zirconium salt solution is less than or equal to that of the first zirconium salt solution; the pH value of the second zirconium salt solution is greater than or equal to that of the first zirconium salt solution. According to the preparation method disclosed by the invention, the nuclear explosion phenomenon is avoided, the uniform distribution of the zirconium element is realized, the electrical property of the battery material prepared by utilizing the zirconium element is improved, the first charge-discharge specific capacity is preferably up to 233 mAh / g or above, and the capacity retention ratio after 100 cycles is preferably up to 95% or above.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery materials technology, and in particular to a method for preparing a zirconium-doped ternary precursor. Background Technology

[0002] Currently, ternary precursors (represented by nickel-cobalt-manganese hydroxide (NCM) and nickel-cobalt-aluminum hydroxide (NCA)) have become a key precursor for lithium-ion battery cathode materials and a core link in the new energy industry chain. Ternary precursors are converted into cathode materials through processes such as high-temperature sintering, and their chemical composition and structure play a decisive role in the electrochemical performance of the battery.

[0003] To further improve the electrochemical performance of ternary precursors, engineers often employ elemental doping. Elemental doping can alter the structure and chemical properties of materials at the atomic level, thereby improving their conductivity, stability, and cycle life. For example, co-precipitation doping in the wet process can ensure that the dopant elements are uniformly distributed in the crystal lattice, improving the uniformity of the cathode material. Uniformly distributed dopant elements can effectively improve the microstructure of the material, enhance its mechanical strength and thermal stability, and thus improve the overall performance of the battery.

[0004] However, while zirconium, a common doping element, can enhance the structural stability of materials, improve electrical conductivity, and enhance battery cycle life, it is prone to hydrolysis in aqueous solutions, forming unstable zirconium hydroxide. This leads to nucleation failure during co-precipitation, which not only affects the uniform distribution of Zr but also results in inhomogeneous microstructure of the material, thereby impacting battery performance and stability.

[0005] For example, CN116177623A discloses a ternary precursor and its preparation method and application. It mainly changes the ratio and time of adding different raw materials to make the distribution of Zr, Co and Al doped and coated in the precursor more uniform. However, it does not consider how to solve the problem of Zr local hydrolysis and core explosion. Its effect on improving battery performance still needs to be improved.

[0006] Therefore, how to provide a method for preparing zirconium-doped ternary precursors, effectively control zirconium hydrolysis, avoid nucleation phenomena, and ensure uniform zirconium doping is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a method for preparing a zirconium-doped ternary precursor. This method solves the problem of zirconium hydrolysis during the synthesis of ternary precursors in existing technologies, avoids the occurrence of nucleus explosion, and allows for controllable and uniform distribution of zirconium doping. The performance of battery materials prepared using the obtained zirconium-doped ternary precursor is significantly improved.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] This invention provides a method for preparing a zirconium-doped ternary precursor, the method comprising the following steps:

[0010] (1) Nucleation stage: The ternary metal salt solution, the first zirconium salt solution, the precipitant solution and the complexing agent solution are added to the base liquid in parallel flow, and the first reaction solution is obtained after the first reaction;

[0011] (2) Growth stage: The ternary metal salt solution, the second zirconium salt solution, the precipitant solution and the complexing agent solution are added in parallel to the first reaction solution in step (1), and the second reaction solution is obtained through the second reaction. The zirconium-doped ternary precursor is then obtained through solid-liquid separation.

[0012] Wherein, in step (2), the temperature of the second zirconium salt solution is less than or equal to the temperature of the first zirconium salt solution in step (1); and in step (2), the pH of the second zirconium salt solution is greater than or equal to the pH of the first zirconium salt solution in step (1).

[0013] The preparation method of the present invention controls the temperature and pH of the zirconium salt solution used in the nucleation and growth stages, so that the temperature of the second zirconium salt solution in step (2) is ≤ the temperature of the first zirconium salt solution in step (1); and the pH of the second zirconium salt solution in step (2) is ≥ the pH of the first zirconium salt solution in step (1), thereby avoiding the explosion of zirconium due to local rapid hydrolysis, thus maintaining the same hydrolysis rate in different stages and achieving uniform and controllable doping of zirconium.

[0014] Preferably, the temperature of the second zirconium salt solution in step (2) is less than the temperature of the first zirconium salt solution in step (1), and the pH of the second zirconium salt solution in step (2) is greater than the pH of the first zirconium salt solution in step (1).

[0015] That is, in the nucleation stage, the present invention uses a first zirconium salt solution with a relatively low temperature and a low pH, which enables Zr to participate in the reaction in the form of polymerized ZrO2 zirconium oxide ions and slowly transform into ZrO2, preventing local agglomeration of Zr and individual nucleation. In the growth stage, a second zirconium salt solution with a lower temperature and a higher pH than the first zirconium salt solution is used. This is because the ternary precursor is not sensitive to temperature fluctuations during the growth stage, but is more sensitive to pH. Therefore, the pH of the zirconium salt solution is increased slightly to prevent nucleation explosion, while the temperature of the zirconium salt solution is decreased slightly to continue to suppress the localized excessively rapid hydrolysis of Zr.

[0016] Preferably, the temperature of the first zirconium salt solution in step (1) is 25~30℃, for example, it can be 25℃, 26℃, 27℃, 28℃, 29℃ or 30℃.

[0017] Preferably, the pH of the first zirconium salt solution in step (1) is 1 to 2, for example, it can be 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 or 2.

[0018] Preferably, the temperature of the second zirconium salt solution in step (2) is 20~25℃, for example, it can be 20℃, 21℃, 22℃, 23℃, 24℃ or 25℃, etc.

[0019] Preferably, the pH of the second zirconium salt solution in step (2) is 2 to 3, for example, it can be 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9 or 3, etc.

[0020] Preferably, the zirconium salts in the first zirconium salt solution in step (1) and the second zirconium salt solution in step (2) are each independently selected from any one or at least a combination of two of zirconium sulfate, zirconium nitrate, or zirconium chloride, wherein typical but non-limiting combinations include combinations of zirconium sulfate and zirconium nitrate, combinations of zirconium sulfate and zirconium chloride, combinations of zirconium nitrate and zirconium chloride, etc.

[0021] Preferably, the concentrations of the first zirconium salt solution in step (1) and the second zirconium salt solution in step (2) are each independently 5~15 g / L, for example, 5 g / L, 8 g / L, 10 g / L, 12 g / L or 15 g / L, etc., preferably 8~12 g / L.

[0022] The present invention further preferably has the concentrations of the first zirconium salt solution in step (1) and the second zirconium salt solution in step (2) each independently being 8~12 g / L, because Zr is less likely to be hydrolyzed in higher concentration zirconium salt solutions.

[0023] Preferably, the ternary metal salt solution in step (1) and the ternary metal salt solution in step (2) have the same metal element.

[0024] Preferably, the metal salt includes nickel salt, cobalt salt, and manganese salt, or the metal salt includes nickel salt, cobalt salt, and aluminum salt.

[0025] Preferably, the nickel salt, the cobalt salt, the manganese salt, and the aluminum salt are each independently selected from any one or a combination of at least two of the sulfate, nitrate, or chloride salts of the corresponding metal, wherein typical but non-limiting combinations include combinations of sulfate and nitrate of the corresponding metal, combinations of nitrate and chloride of the corresponding metal, or combinations of sulfate and chloride of the corresponding metal, etc.

[0026] Preferably, the total metal concentration of the ternary metal salt solution in step (1) and the ternary metal salt solution in step (2) is independently 1.5~2.5 mol / L, for example, it can be 1.5 mol / L, 1.8 mol / L, 2.0 mol / L, 2.2 mol / L or 2.5 mol / L, etc.

[0027] Preferably, with the total molar percentage of metal elements in the ternary metal salt solution being 100 mol%, the molar ratio of nickel, cobalt, and manganese in the ternary metal salt solution is (90~98):(1~4):(1~6), for example, it can be 90:4:6, 92:3:5, 94:3:3, 96:2:2, or 98:1:1, etc.

[0028] Preferably, with the total molar percentage of metal elements in the ternary metal salt solution being 100 mol%, the molar ratio of nickel, cobalt, and aluminum in the ternary metal salt solution is (85~90):(10~15):(0.1~5), for example, it can be 85:10:5, 86:11:3, 87:10:3, 88:11:1, or 89:10:1, etc.

[0029] Preferably, the precipitant solution in step (1) and the precipitant solution in step (2) are each independently selected from any one or at least a combination of two of sodium hydroxide solution, sodium carbonate solution, or sodium bicarbonate solution, wherein typical but non-limiting combinations include combinations of sodium hydroxide solution and sodium carbonate solution, combinations of sodium carbonate solution and sodium bicarbonate solution, or combinations of sodium hydroxide solution and sodium bicarbonate solution, etc.

[0030] Preferably, the concentrations of the precipitant solution in step (1) and the precipitant solution in step (2) are each independently 300~400 g / L, for example, 300 g / L, 320 g / L, 340 g / L, 360 g / L or 400 g / L, etc.

[0031] Preferably, the complexing agent solution in step (1) and the complexing agent solution in step (2) are each independently selected from any one or at least a combination of two of ammonia solution, oxalic acid or citric acid, wherein typical but non-limiting combinations include a combination of ammonia solution and oxalic acid, a combination of oxalic acid and citric acid, or a combination of ammonia solution and citric acid, etc.

[0032] Preferably, the concentrations of the complexing agent solution in step (1) and the complexing agent solution in step (2) are each independently 150~200 g / L, for example, 150 g / L, 160 g / L, 170 g / L, 180 g / L, 190 g / L or 200 g / L, etc.

[0033] Preferably, the temperatures of the first reaction in step (1) and the second reaction in step (2) are each independently 60~80℃, for example, 60℃, 62℃, 65℃, 68℃, 70℃, 72℃, 75℃, 78℃ or 80℃, etc.

[0034] Preferably, the pH of the reaction systems for the first reaction in step (1) and the second reaction in step (2) is independently 11 to 12, for example, 11, 11.2, 11.5, 11.8 or 12.

[0035] Preferably, the ammonium concentration in the reaction systems of the first reaction in step (1) and the second reaction in step (2) is independently 10~15 g / L, for example, it can be 10 g / L, 11 g / L, 12 g / L, 13 g / L, 14 g / L or 15 g / L, etc.

[0036] Preferably, the time for the first reaction in step (1) and the second reaction in step (2) is independently 1 to 4 hours, for example, it can be 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours or 4 hours.

[0037] Preferably, the first reaction in step (1) is accompanied by a first stirring, and / or the second reaction in step (2) is accompanied by a second stirring.

[0038] Preferably, the rotation speed of the first stirring and the second stirring is independently 200~300 r / min, for example, it can be 200 r / min, 210 r / min, 220 r / min, 230 r / min, 240 r / min, 250 r / min, 260 r / min, 270 r / min, 280 r / min, 290 r / min or 300 r / min, etc.

[0039] Preferably, the endpoint of the first reaction in step (1) is that the particle size D50 of the ternary precursor core in the first reaction solution is 0.5~2 μm, for example, it can be 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.8 μm or 2 μm, etc.

[0040] Preferably, the endpoint of the second reaction in step (2) is that the particle size D50 of the zirconium-doped ternary precursor in the second reaction solution is 10~15 μm, for example, it can be 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm or 15 μm, etc.

[0041] Preferably, step (2) in the preparation method further includes washing and drying the zirconium-doped ternary precursor sequentially.

[0042] The purpose of the washing is to remove Na and / or other impurities.

[0043] Preferably, the washing temperature is 50~80℃, for example, it can be 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃, etc.

[0044] Preferably, the drying temperature is 150~180℃, for example, it can be 150℃, 155℃, 160℃, 165℃, 170℃, 175℃ or 180℃, etc.

[0045] Preferably, based on a zirconium-doped ternary precursor mass content of 100 wt%, the zirconium doping amount in the zirconium-doped ternary precursor is 0.1~0.5 wt%, for example, it can be 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.45 wt%, or 0.5 wt%, etc.

[0046] Compared with the prior art, the present invention has at least the following beneficial effects:

[0047] The method for preparing zirconium-doped ternary precursors provided by this invention avoids excessively rapid local hydrolysis of Zr by adjusting the temperature and pH of the zirconium salt solution used in different reaction stages, so that Zr maintains the same hydrolysis rate in different stages, avoids nucleus explosion, and makes the doping more uniform and the content controllable. In addition, the battery material prepared using the obtained zirconium-doped ternary precursor has an optimal initial charge-discharge specific capacity of more than 233 mAh / g under 0.1C / 0.5C test conditions, and an optimal capacity retention rate of more than 95% after 100 cycles. Attached Figure Description

[0048] Figure 1 This is a SEM image of the zirconium-doped ternary precursor obtained by the preparation method provided in Example 1 of this invention. Detailed Implementation

[0049] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0050] In the preparation methods described in the following examples or comparative examples, the first and second reactions are carried out in the same reactor, and the reactor is in a nitrogen atmosphere.

[0051] I. Implementation Examples

[0052] Example 1

[0053] This embodiment provides a method for preparing a zirconium-doped ternary precursor, the method comprising the following steps:

[0054] (1) Nucleation stage: The ternary metal salt solution, the first zirconium salt solution (zirconium nitrate solution), the sodium hydroxide solution and the ammonia solution were added to the base liquid (water and sodium hydroxide solution (350g / L) in a volume ratio of 1:9) in parallel. The first reaction solution was obtained by the first reaction at 70℃, pH=11.5 and the first stirring speed was 250r / min. The endpoint of the first reaction was that the particle size D50 of the ternary precursor nucleus in the first reaction solution was 1.2μm.

[0055] (2) Growth stage: The ternary metal salt solution, the second zirconium salt solution (zirconium nitrate solution), the sodium hydroxide solution and the ammonia solution are added in parallel to the first reaction solution in step (1). Under the conditions of 70°C, pH=11.5 and the second stirring speed of 250r / min, the second reaction solution is obtained by the second reaction. The zirconium-doped ternary precursor is then obtained by filtration. The zirconium-doped ternary precursor is then washed with hot water at 70°C and dried in a rotary kiln at 160°C. The endpoint of the second reaction is that the particle size D50 of the zirconium-doped ternary precursor in the second reaction solution is 12.5μm.

[0056] In step (1), the temperature of the first zirconium salt solution is 28°C, the pH is 1.5, and the concentration is 12 g / L; in step (2), the temperature of the second zirconium salt solution is 23°C, the pH is 2.5, and the concentration is 12 g / L.

[0057] The ternary metal salt solution in step (1) is the same as the ternary metal salt solution in step (2), wherein the metal salts include nickel sulfate, cobalt sulfate and manganese sulfate, and the total metal concentration is 2 mol / L. Based on the total molar percentage of metal elements in the ternary metal salt solution being 100 mol%, the molar ratio of nickel, cobalt and manganese in the ternary metal salt solution is 95:2:3.

[0058] The concentrations of the sodium hydroxide solution in step (1) and the sodium hydroxide solution in step (2) are both 350 g / L; the concentrations of the ammonia solution in step (1) and the ammonia solution in step (2) are both 180 g / L.

[0059] The ammonium concentration in the reaction systems of the first reaction in step (1) and the second reaction in step (2) is 12 g / L.

[0060] In this embodiment, the zirconium-doped ternary precursor, namely the zirconium-doped nickel-cobalt-manganese ternary precursor, has a zirconium doping content of 0.25 wt%. Figure 1 As shown in the figure, the Zr element is evenly distributed and the particle size distribution is uniform.

[0061] Example 2

[0062] This embodiment provides a method for preparing a zirconium-doped ternary precursor, the method comprising the following steps:

[0063] (1) Nucleation stage: The ternary metal salt solution, the first zirconium salt solution (zirconium sulfate solution), the sodium hydroxide solution and the ammonia solution are added to the base liquid (water and sodium hydroxide solution (300g / L) in a volume ratio of 1:9) in parallel. The first reaction solution is obtained by the first reaction at 60℃, pH=11 and the first stirring speed is 300r / min. The endpoint of the first reaction is that the particle size D50 of the ternary precursor nucleus in the first reaction solution is 2μm.

[0064] (2) Growth stage: The ternary metal salt solution, the second zirconium salt solution (zirconium sulfate solution), the sodium hydroxide solution and the ammonia solution are added in parallel to the first reaction solution in step (1). Under the conditions of 60°C, pH=11 and the second stirring speed of 300r / min, the second reaction is carried out to obtain the second reaction solution. The zirconium-doped ternary precursor is then obtained by filtration. The zirconium-doped ternary precursor is then washed with hot water at 80°C and dried in a rotary kiln at 180°C. The endpoint of the second reaction is that the particle size D50 of the zirconium-doped ternary precursor in the second reaction solution is 10μm.

[0065] In step (1), the temperature of the first zirconium salt solution is 25°C, the pH is 2, and the concentration is 8 g / L; in step (2), the temperature of the second zirconium salt solution is 20°C, the pH is 3, and the concentration is 8 g / L.

[0066] The ternary metal salt solution in step (1) is the same as the ternary metal salt solution in step (2), wherein the metal salts include nickel nitrate, cobalt nitrate and manganese nitrate, and the total metal concentration is 1.5 mol / L. Based on the total molar percentage of metal elements in the ternary metal salt solution being 100 mol%, the molar ratio of nickel, cobalt and manganese in the ternary metal salt solution is 90:4:6.

[0067] The concentrations of the sodium hydroxide solution in step (1) and the sodium hydroxide solution in step (2) are both 300 g / L; the concentrations of the ammonia solution in step (1) and the ammonia solution in step (2) are both 150 g / L.

[0068] The ammonium concentration in the reaction systems of the first reaction in step (1) and the second reaction in step (2) is 10 g / L.

[0069] In this embodiment, the zirconium-doped ternary precursor, namely the zirconium-doped nickel-cobalt-manganese ternary precursor, has a zirconium doping amount of 0.1 wt%, a uniform Zr element distribution, and a uniform particle size distribution.

[0070] Example 3

[0071] This embodiment provides a method for preparing a zirconium-doped ternary precursor, the method comprising the following steps:

[0072] (1) Nucleation stage: The ternary metal salt solution, the first zirconium salt solution (zirconium chloride solution), the sodium hydroxide solution and the ammonia solution are added to the base liquid (water and sodium hydroxide solution (400g / L) in a volume ratio of 2:8) in parallel. The first reaction solution is obtained by the first reaction at 80℃, pH=12 and the first stirring speed is 200r / min. The endpoint of the first reaction is that the particle size D50 of the ternary precursor nucleus in the first reaction solution is 0.5μm.

[0073] (2) Growth stage: The ternary metal salt solution, the second zirconium salt solution (zirconium chloride solution), the sodium hydroxide solution and the ammonia solution are added in parallel to the first reaction solution in step (1). Under the conditions of 80°C, pH=12 and the second stirring speed of 200r / min, the second reaction solution is obtained by the second reaction. The zirconium-doped ternary precursor is then obtained by filtration. The zirconium-doped ternary precursor is then washed with hot water at 50°C and dried in a rotary kiln at 150°C. The endpoint of the second reaction is that the particle size D50 of the zirconium-doped ternary precursor in the second reaction solution is 15μm.

[0074] In step (1), the temperature of the first zirconium salt solution is 30°C, the pH is 1, and the concentration is 10 g / L; in step (2), the temperature of the second zirconium salt solution is 25°C, the pH is 2, and the concentration is 10 g / L.

[0075] The ternary metal salt solution in step (1) is the same as the ternary metal salt solution in step (2), wherein the metal salts include nickel nitrate, cobalt nitrate and aluminum nitrate, and the total metal concentration is 2.5 mol / L. Based on the total molar percentage of metal elements in the ternary metal salt solution being 100 mol%, the molar ratio of nickel, cobalt and aluminum in the ternary metal salt solution is 85:10:5.

[0076] The concentrations of the sodium hydroxide solution in step (1) and the sodium hydroxide solution in step (2) are both 400 g / L; the concentrations of the ammonia solution in step (1) and the ammonia solution in step (2) are both 200 g / L.

[0077] The ammonium concentration in the reaction systems of the first reaction in step (1) and the second reaction in step (2) is 15 g / L.

[0078] In this embodiment, the zirconium-doped ternary precursor, namely the zirconium-doped nickel-cobalt-aluminum ternary precursor, has a zirconium doping amount of 0.5 wt%, a uniform Zr element distribution, and a uniform particle size distribution.

[0079] Example 4

[0080] This embodiment provides a method for preparing a zirconium-doped ternary precursor. Except for step (2), where the temperature of the second zirconium salt solution is 28°C, the preparation method is the same as in Example 1.

[0081] Example 5

[0082] This embodiment provides a method for preparing a zirconium-doped ternary precursor. Except for step (2), in which the pH of the second zirconium salt solution is 1.5, the preparation method is the same as in Example 1.

[0083] Example 6

[0084] This embodiment provides a method for preparing a zirconium-doped ternary precursor. Except for step (2), where the temperature of the second zirconium salt solution is 18°C, the preparation method is the same as in Example 1.

[0085] Example 7

[0086] This embodiment provides a method for preparing a zirconium-doped ternary precursor. Except for step (2), where the pH of the second zirconium salt solution is 3.2, the preparation method is the same as in Example 1.

[0087] Example 8

[0088] This embodiment provides a method for preparing a zirconium-doped ternary precursor. Except for step (1), where the temperature of the first zirconium salt solution is 35°C, the preparation method is the same as in Example 1.

[0089] Example 9

[0090] This embodiment provides a method for preparing a zirconium-doped ternary precursor. Except for step (1) where the pH of the first zirconium salt solution is 2.2, the preparation method is the same as in Example 1.

[0091] Example 10

[0092] This embodiment provides a method for preparing a zirconium-doped ternary precursor. Except that the concentration of the first zirconium salt solution in step (1) and the first zirconium salt solution in step (2) are both 5 g / L, the preparation method is the same as in Example 1.

[0093] Example 11

[0094] This embodiment provides a method for preparing a zirconium-doped ternary precursor. Except that the concentration of the first zirconium salt solution in step (1) and the first zirconium salt solution in step (2) are both 15 g / L, the preparation method is the same as in Example 1.

[0095] II. Comparative Example

[0096] Comparative Example 1

[0097] This comparative example provides a method for preparing a zirconium-doped ternary precursor. Except for step (2), where the temperature of the second zirconium salt solution is 30°C, the preparation method is the same as in Example 1.

[0098] Comparative Example 2

[0099] This comparative example provides a method for preparing a zirconium-doped ternary precursor. Except for step (2), in which the pH of the second zirconium salt solution is 1.2, the preparation method is the same as in Example 1.

[0100] Comparative Example 3

[0101] This comparative example provides a method for preparing a zirconium-doped ternary precursor. Except for step (2), where the temperature of the second zirconium salt solution is 30°C and the pH is 1.2, the preparation method is the same as in Example 1.

[0102] III. Tests and Results

[0103] ① Observe whether there is a nucleation phenomenon in the preparation method described in the above embodiments or comparative examples, test and calculate the doping amount of zirconium and the zirconium distribution in the obtained zirconium-doped ternary precursor, and the results are shown in Table 1.

[0104] ② Battery materials were prepared using the zirconium-doped ternary precursors obtained in the above examples or comparative examples, and charge-discharge tests were conducted to obtain the first discharge specific capacity and capacity retention rate after 100 cycles. The results are shown in Table 1.

[0105] The battery is prepared as follows: the zirconium-doped ternary precursor obtained in the above examples or comparative examples is mixed with a binder (polyvinylidene fluoride PVDF) and conductive carbon black in a mass ratio of 8:1:1, and then N-methylpyrrolidone is added to form a positive electrode slurry. The positive electrode slurry is then coated on an aluminum foil to obtain a positive electrode sheet; a lithium sheet is used as a negative electrode sheet; the electrolyte is 1 mol / L lithium hexafluorophosphate (the solvent is ethylene carbonate, diethyl carbonate and dimethyl carbonate in a volume ratio of 1:1:1), the separator is a polypropylene separator, and the cells are assembled into a coin cell.

[0106] The test conditions for the charge-discharge test are as follows: the electrochemical performance of the above-mentioned coin cell is tested at 0.1 / 0.5C, and the test voltage is 3~4.55V;

[0107] Table 1

[0108]

[0109] The data in Table 1 shows that:

[0110] (1) As can be seen from Examples 1 to 3, the method for preparing zirconium-doped ternary precursors provided by the present invention avoids the occurrence of nucleus explosion by synergistically controlling the temperature and pH of the zirconium salt solution used in different reaction stages, so that the zirconium element is evenly distributed and the doping amount is controllable, thus preparing high-performance battery materials with a first charge-discharge specific capacity of up to 233 mAh / g and a capacity retention rate of up to 95% after 100 cycles.

[0111] (2) It can be seen from the combined examples 1 and 4 to 5 that, since only the pH of the second zirconium salt solution was adjusted in the growth stage of step (2) of example 4, and the temperature was not reduced, the problem of local hydrolysis of Zr element was not solved, resulting in a deterioration in the performance of the battery material prepared using it; since only the temperature of the second zirconium salt solution was adjusted in the growth stage of step (2) of example 5, and the pH was not increased, the nucleus exploded, affecting the performance of the subsequent battery material. This shows that the present invention further prefers that the temperature of the second zirconium salt solution in step (2) is < the temperature of the first zirconium salt solution in step (1), and the pH of the second zirconium salt solution in step (2) is > the pH of the first zirconium salt solution in step (1). The combined effect of temperature and pH makes the quality of the zirconium-doped ternary precursor material higher, thereby improving the performance of the battery material prepared using it.

[0112] (3) It can be seen from the comprehensive examples 1 and 6 to 9 that, due to the low temperature of the second zirconium salt solution in the growth stage of step (2) in example 6, the diffusion is poor and the zirconium distribution is uneven; due to the high pH of the second zirconium salt solution in the growth stage of step (2) in example 7, the zirconium hydrolysis is aggravated and the nucleus explodes; due to the high temperature of the first zirconium salt solution in the nucleation stage of step (1) in example 8, the zirconium distribution is uneven; due to the high pH of the first zirconium salt solution in the nucleation stage of step (1) in example 9, the zirconium distribution is uneven. Therefore, it is indicated that the present invention further preferably uses the temperature of the first zirconium salt solution in step (1) as 25~30℃, the pH of the first zirconium salt solution in step (1) as 1~2, the temperature of the second zirconium salt solution in step (2) as 20~25℃, and the pH of the second zirconium salt solution in step (2) as 2~3, which improves the quality of the obtained zirconium-doped ternary precursor and thus improves the comprehensive performance of the battery material prepared using it.

[0113] (4) As can be seen from the combined examples 1, 10 and 11, the present invention further optimizes the concentration of the first zirconium salt solution in step (1) and the second zirconium salt solution in step (2) to be 8~12 g / L, thereby making the zirconium-doped ternary precursor of higher quality and further improving the performance of the battery prepared using it.

[0114] (5) It can be seen from the comprehensive examples 1 and Comparative Examples 1 to 3 that, due to the high temperature of the second zirconium salt solution in step (2) of Comparative Example 1, the hydrolysis of zirconium salt is aggravated, resulting in nucleation and uneven distribution; due to the low pH of the second zirconium salt solution in step (2) of Comparative Example 2, diffusion is hindered and zirconium distribution is uneven; due to the high temperature of the second zirconium salt solution in step (2) and the low pH of the second zirconium salt solution in Comparative Example 3, both nucleation and uneven distribution occur; This shows that the present invention specifically selects the temperature of the second zirconium salt solution in step (2) to be ≤ the temperature of the first zirconium salt solution in step (1), and the pH of the second zirconium salt solution in step (2) to be ≥ the pH of the first zirconium salt solution in step (1), so as to coordinately regulate the temperature and pH of the zirconium salt solution at different stages, avoid the nucleation phenomenon, improve the uniformity of zirconium distribution, and thus provide the electrical performance of the battery prepared using the zirconium-doped ternary precursor and extend its service life.

[0115] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a zirconium-doped ternary precursor, characterized in that, The preparation method includes the following steps: (1) Nucleation stage: The ternary metal salt solution, the first zirconium salt solution, the precipitant solution and the complexing agent solution are added to the base liquid in parallel flow, and the first reaction solution is obtained after the first reaction; (2) Growth stage: The ternary metal salt solution, the second zirconium salt solution, the precipitant solution and the complexing agent solution are added in parallel to the first reaction solution in step (1), and the second reaction solution is obtained through the second reaction. The zirconium-doped ternary precursor is then obtained through solid-liquid separation. Wherein, in step (2), the temperature of the second zirconium salt solution is less than or equal to the temperature of the first zirconium salt solution in step (1); and in step (2), the pH of the second zirconium salt solution is greater than or equal to the pH of the first zirconium salt solution in step (1).

2. The preparation method according to claim 1, characterized in that, In step (2), the temperature of the second zirconium salt solution is less than the temperature of the first zirconium salt solution in step (1), and the pH of the second zirconium salt solution in step (2) is greater than the pH of the first zirconium salt solution in step (1).

3. The preparation method according to claim 1 or 2, characterized in that, Step (1) The temperature of the first zirconium salt solution is 25~30℃; Preferably, in step (1), the pH of the first zirconium salt solution is 1 to 2; Preferably, in step (2), the temperature of the second zirconium salt solution is 20~25℃; Preferably, the pH of the second zirconium salt solution in step (2) is 2 to 3.

4. The preparation method according to any one of claims 1 to 3, characterized in that, In step (1), the first zirconium salt solution and in step (2), the second zirconium salt solution each independently selects one or a combination of at least two of zirconium sulfate, zirconium nitrate, or zirconium chloride; Preferably, the concentrations of the first zirconium salt solution in step (1) and the second zirconium salt solution in step (2) are each independently 5~15 g / L, preferably 8~12 g / L.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The ternary metal salt solution in step (1) has the same metal element as the ternary metal salt solution in step (2); Preferably, the metal salt includes nickel salt, cobalt salt, and manganese salt; or, the metal salt includes nickel salt, cobalt salt, and aluminum salt. Preferably, the nickel salt, the cobalt salt, the manganese salt, and the aluminum salt are each independently selected from any one or a combination of at least two of the sulfate, nitrate, or chloride salts of the corresponding metal.

6. The preparation method according to any one of claims 1 to 5, characterized in that, The total metal concentrations of the ternary metal salt solution in step (1) and the ternary metal salt solution in step (2) are each independently 1.5~2.5 mol / L; Preferably, with the total molar percentage of metal elements in the ternary metal salt solution being 100 mol%, the molar ratio of nickel, cobalt, and manganese in the ternary metal salt solution is (90~98):(1~4):(1~6); Preferably, with the total molar percentage of metal elements in the ternary metal salt solution being 100 mol%, the molar ratio of nickel, cobalt, and aluminum in the ternary metal salt solution is (85~90):(10~15):(0.1~5).

7. The preparation method according to any one of claims 1 to 6, characterized in that, The precipitant solution in step (1) and the precipitant solution in step (2) are each independently selected from any one or a combination of at least two of sodium hydroxide solution, sodium carbonate solution, or sodium bicarbonate solution; Preferably, the concentrations of the precipitant solution in step (1) and the precipitant solution in step (2) are each independently 300~400g / L; Preferably, the complexing agent solution in step (1) and the complexing agent solution in step (2) are each independently selected from any one or a combination of at least two of ammonia solution, oxalic acid, or citric acid; Preferably, the concentrations of the complexing agent solution in step (1) and the complexing agent solution in step (2) are each independently 150~200 g / L.

8. The preparation method according to any one of claims 1 to 7, characterized in that, The temperatures of the first reaction in step (1) and the second reaction in step (2) are each independently 60~80℃; Preferably, the pH of the reaction systems for the first reaction in step (1) and the second reaction in step (2) is independently 11-12; Preferably, the ammonium concentration in the reaction systems of the first reaction in step (1) and the second reaction in step (2) is independently 10~15 g / L; Preferably, the time for the first reaction in step (1) and the second reaction in step (2) are each 1~4h independently; Preferably, the first reaction in step (1) is accompanied by a first stirring, and / or the second reaction in step (2) is accompanied by a second stirring; Preferably, the rotation speeds of the first stirring and the second stirring are each independently 200~300 r / min.

9. The preparation method according to any one of claims 1 to 8, characterized in that, Step (1) The endpoint of the first reaction is that the particle size D50 of the ternary precursor core in the first reaction solution is 0.5~2μm; Preferably, the endpoint of the second reaction in step (2) is that the particle size D50 of the zirconium-doped ternary precursor in the second reaction solution is 10~15μm.

10. The preparation method according to any one of claims 1 to 9, characterized in that, Step (2) in the preparation method further includes washing and drying the zirconium-doped ternary precursor in sequence; Preferably, the washing temperature is 50~80℃; Preferably, the drying temperature is 150~180℃; Preferably, based on a zirconium-doped ternary precursor mass content of 100 wt%, the zirconium doping amount in the zirconium-doped ternary precursor is 0.1~0.5 wt%.

Images