High specific surface low sodium sulfur ternary precursor, preparation method and application thereof

Abstract

The application discloses a high specific surface low-sodium sulfur ternary precursor and a preparation method and application thereof. The preparation method comprises the following steps: adding a nickel-cobalt-manganese salt solution, a precipitant and a complexing agent into a first reaction kettle, and performing a co-precipitation reaction under an inert atmosphere to obtain crystal nuclei with a particle size D50 of 1.0-1.6 microns; adding the crystal nuclei, the nickel-cobalt-manganese salt solution, the precipitant and the complexing agent into a second reaction kettle, first performing a co-precipitation reaction under an inert atmosphere, then performing a co-precipitation reaction under an oxidizing atmosphere, stopping the reaction when the particle size D50 of the product is 3.8-4.2 microns, and obtaining the high specific surface low-sodium sulfur ternary precursor. The ternary precursor prepared by the application has the advantages of narrow particle size distribution, good sphericity, thin flake-like primary particles growing along the radial direction, porous secondary particles, high batch stability of the product and convenient production operation.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery cathode material technology, specifically to a high specific surface area, low sodium and sulfur ternary precursor, its preparation method, and its application. Background Technology

[0002] As a key component of lithium-ion batteries, cathode materials have a decisive impact on the battery's electrochemical performance. In recent years, layered Ni-Co-Mn ternary composite materials have been widely used in the electric vehicle field due to their high specific capacity, low cost, and long cycle life. Ternary precursors, as raw materials for the preparation of ternary cathode materials, largely determine the performance of these materials. Currently, the mainstream method for industrial production of ternary precursors is the co-precipitation method. The particle size, tap density, specific surface area, and morphology of the ternary precursors play a decisive role in the performance of the ternary cathode materials. High specific surface area and low sodium-sulfur ternary precursors, with their higher specific surface area, can provide more active sites and achieve higher capacity even with relatively high nickel content. Furthermore, the higher specific surface area and lower sodium-sulfur content can improve the ion transport rate and electron transport rate of the material, thereby improving the battery's cycle life and stability.

[0003] Currently, the production of high specific surface area and low sodium-sulfur ternary precursors mostly employs low-alkalinity continuous processes or purely intermittent oxidation processes. Continuous processes, due to their lower alkalinity and poor complexation, lead to increased difficulty in particle size control, resulting in a wide particle size distribution, poor batch stability, uneven primary particle growth direction and size, and irregular secondary particle morphology. Purely intermittent processes cannot precisely control the nucleation rate in the early stages of reactor preparation, leading to irregular growth durations: if the growth rate is too fast, the product has a wide particle size distribution, poor sphericity, obvious twinning, and disordered primary particle growth; if the growth rate is too slow, the primary particles are too thick, the interparticle gaps are too small, resulting in an excessively high tap density and a small specific surface area, leading to significant ball breakage during sintering, affecting battery capacity and cycle performance. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0005] Therefore, in a first aspect, the present invention provides a method for preparing a high specific surface area, low sodium and sulfur ternary precursor, wherein a nickel cobalt manganese salt solution, a precipitant and a complexing agent are added to a first reaction vessel and a co-precipitation reaction is carried out under an inert atmosphere to obtain crystal nuclei with a particle size D50 of 1.0 μm to 1.6 μm.

[0006] The crystal nuclei, nickel-cobalt-manganese salt solution, precipitant, and complexing agent are added to the second reactor. Co-precipitation reaction is first carried out under an inert atmosphere, followed by co-precipitation reaction under an oxidizing atmosphere. The reaction is stopped when the product particle size D50 is 3.8 μm to 4.2 μm to obtain the high specific surface area, low sodium-sulfur ternary precursor.

[0007] Furthermore, the coprecipitation reaction in the first reactor includes:

[0008] The influent flow rate of the nickel-cobalt-manganese salt solution is 4 L / h to 6 L / h, and the influent concentration is 1.8 mol / L to 2.4 mol / L.

[0009] The reaction temperature was 60℃~70℃, the pH value was 11.6~11.8, and the homogenization rate was 700rpm~800rpm.

[0010] Furthermore, the coprecipitation reaction first carried out under an inert atmosphere includes:

[0011] The initial nucleus content of the reaction is 120 g / L to 130 g / L;

[0012] The influent flow rate of the nickel-cobalt-manganese salt solution is 2 L / h to 4 L / h, and the influent concentration is 1.8 mol / L to 2.4 mol / L.

[0013] The reaction temperature was 60℃~70℃, the reaction time was 4h~5h, the pH value was 11.1~11.5, and the homogenization rate was 600rpm~700rpm.

[0014] Further, the coprecipitation reaction under an oxidizing atmosphere includes:

[0015] Increase the flow rate of the nickel-cobalt-manganese salt solution by 0.5 L / h to 1 L / h every 4 to 12 hours;

[0016] Reduce the homogenization speed by 2 to 10 rpm every 4 to 12 hours;

[0017] Decrease the reaction pH by 0.02–0.04 every 4–12 hours;

[0018] The initial airflow rate is 1m 3 / h~3m 3 / h, when the particle size D50 of the product is 2.8μm~3.2μm, increase the air flow rate by 0.4m. 3 / h~0.6m 3 / h.

[0019] Furthermore, the precipitant is a sodium hydroxide solution with an influent concentration of 6 mol / L to 12 mol / L;

[0020] The concentration of the complexing agent ammonia solution in the influent is 4 mol / L to 10 mol / L.

[0021] The ammonia concentration in the first reaction vessel is controlled to be 1 g / L to 5 g / L;

[0022] The ammonia concentration in the second reaction vessel is controlled to be 1 g / L to 5 g / L.

[0023] Furthermore, in the nickel-cobalt-manganese salt solution, the molar ratio of nickel, cobalt, and manganese is X:Y:Z, satisfying X+Y+Z=1, and 0.6≤X<1, 0<Y<0.4, and 0<Z<0.4.

[0024] Furthermore, the high specific surface area and low sodium-sulfur ternary precursor has a specific surface area of ​​18±2 m². 2 / g, tap density is 1.70±0.2g / cm³ 3 The particle size distribution has a diameter of 0.75±0.1, sodium content <70ppm, sulfur content <800ppm, and D50 of 4±0.2μm.

[0025] In a second aspect, the present invention provides a high specific surface area, low sodium and sulfur ternary precursor, which is obtained by the above-described method for preparing a high specific surface area, low sodium and sulfur ternary precursor.

[0026] In a third aspect, the present invention provides a cathode material, wherein the cathode material is prepared by mixing the above-mentioned high specific surface area, low sodium and sulfur ternary precursor with a lithium source.

[0027] In a fourth aspect, the present invention provides a lithium-ion battery, wherein the positive electrode material of the lithium-ion battery is prepared by mixing the above-mentioned high specific surface area, low sodium and sulfur ternary precursor with a lithium source.

[0028] Beneficial effects:

[0029] The present invention provides a method for preparing a high specific surface area, low sodium-sulfur ternary precursor. The method involves preparing crystal nuclei with a particle size (D50) of 1.0 μm to 1.6 μm in a first reactor, then adding the nuclei to a second reactor for co-precipitation under an inert atmosphere followed by co-precipitation under an oxidizing atmosphere, resulting in a ternary precursor with a D50 of 3.8 μm to 4.2 μm. Compared to existing technologies, this method offers at least the following advantages: reduced particle size distribution of the ternary precursor, improved stability of the growth process control and batch consistency of the product, orderly growth of primary particles into thin flakes, and porous secondary particles with good sphericity and a low number of twin spheres, thereby improving process parameters such as tap density, specific surface area, and particle size distribution, ultimately producing a high specific surface area, low sodium-sulfur ternary precursor. Attached Figure Description

[0030] Figure 1 SEM image of the high specific surface area, low sodium and sulfur ternary precursor prepared in Example 1 of this application.

[0031] Figure 2 SEM image of the high specific surface area, low sodium and sulfur ternary precursor prepared in Example 2 of this application.

[0032] Figure 3SEM image of the high specific surface area, low sodium and sulfur ternary precursor prepared in Example 3 of this application. Detailed Implementation

[0033] To better understand the above technical solutions, the technical solutions of this application will be described in detail below through specific embodiments.

[0034] In a first aspect, this invention provides a method for preparing a high specific surface area, low sodium and sulfur ternary precursor, wherein a nickel-cobalt-manganese salt solution, a precipitant and a complexing agent are added to a first reaction vessel, and a co-precipitation reaction is carried out under an inert atmosphere to obtain crystal nuclei with a particle size D50 of 1.0 μm to 1.6 μm.

[0035] The crystal nuclei, nickel-cobalt-manganese salt solution, precipitant, and complexing agent are added to the second reactor. Co-precipitation reaction is first carried out under an inert atmosphere, followed by co-precipitation reaction under an oxidizing atmosphere. The reaction is stopped when the product particle size D50 is 3.8 μm to 4.2 μm to obtain the high specific surface area, low sodium-sulfur ternary precursor.

[0036] The method for preparing a high specific surface area, low sodium-sulfur ternary precursor provided in this invention employs a quantitative nucleation and quantitative oxygenation process. This process mainly consists of two steps: The first step involves producing crystal nuclei with a small number of twin spheres, a narrow particle size distribution, and a large specific surface area. This is a single-stage continuous process. After preparing the base solution, feeding begins. Feeding is stopped once the particle size index D50 is stabilized by adjusting process parameters, and the resulting crystal nuclei are stored for later use. The second step involves producing crystal nuclei with good sphericity, a narrower particle size distribution, ordered primary particle growth direction, and large inter-particle gaps. The ternary precursor was produced using a purely intermittent method. A separate synthesis reactor was selected to prepare the base solution. The crystal nuclei were poured into the synthesis reactor and an intermittent concentration reaction was carried out. After a period of reaction, oxygen was introduced. The process parameters were adjusted to change the growth mode and thickness of the primary particles, so that the primary particles grew in an orderly, sheet-like manner, and the secondary particles exhibited a porous distribution with a small number of twins, good sphericity, and high consistency. The reaction was stopped when the D50 was 3.8μm to 4.2μm. The product was then aged, washed, and dried to obtain a high specific surface area, low sodium sulfur precursor.

[0037] The method for preparing a high specific surface area, low sodium and sulfur ternary precursor provided in this invention reduces the particle size distribution of the ternary precursor compared to the prior art, improves the stability of the growth process control and the consistency of product batches, ensures orderly growth of primary particles into thin flakes, and results in porous secondary particles with good sphericity and a small number of twin spheres, thereby improving process indicators such as tap density, specific surface area, and particle size distribution, and producing a high specific surface area, low sodium and sulfur ternary precursor.

[0038] In some embodiments, the co-precipitation reaction in the first reactor includes: a feed flow rate of 4 L / h to 6 L / h for the nickel cobalt manganese salt solution, a feed concentration of 1.8 mol / L to 2.4 mol / L; a reaction temperature of 60°C to 70°C; a pH value of 11.6 to 11.8; and a homogenization rate of 700 rpm to 800 rpm.

[0039] Specifically, before the reaction, according to NiSO4, CoSO4 4、 A mixed nickel-cobalt salt solution with a concentration of 1.8 mol / L to 2.4 mol / L was prepared using MnSO4 in a ratio of X:Y:Z, where X+Y+Z=1, 0.6≤X<1, 0<Y<0.4, and 0<Z<0.4. A 6 mol / L to 12 mol / L NaOH solution was prepared as a precipitant, and a 4 mol / L to 10 mol / L ammonia solution was prepared as a complexing agent. By controlling the ammonia concentration in the first reaction vessel to 1 g / L to 5 g / L, the influent flow rate of the nickel-cobalt-manganese salt solution to 4 L / h to 6 L / h, the co-precipitation reaction temperature to 60℃ to 70℃, the pH value to 11.6 to 11.8, and the homogenization speed to 700 rpm to 800 rpm, crystal nuclei with good sphericity, few twinned spheres, a solid content of 120 g / L to 130 g / L, and a uniform particle size distribution (D50) of 1.0 μm to 1.6 μm were obtained.

[0040] In some embodiments, the coprecipitation reaction in the second reactor is carried out as follows: First, the coprecipitation reaction is conducted under an inert atmosphere, specifically: the initial nucleus content is 120 g / L to 130 g / L; the inlet flow rate of the nickel-cobalt-manganese salt solution is 2 L / h to 4 L / h, and the inlet concentration is 1.8 mol / L to 2.4 mol / L; the reaction temperature is 60℃ to 70℃, the reaction time is 4 h to 5 h, the pH value is 11.1 to 11.5, and the homogenization rate is 600 rpm to 700 rpm. Then, the coprecipitation reaction is carried out under an oxidizing atmosphere, specifically: the flow rate of the nickel-cobalt-manganese salt solution is increased by 0.5 L / h to 1 L / h every 4 to 12 h; the homogenization rate is decreased by 2 rpm to 10 rpm every 4 to 12 h; the reaction pH value is decreased by 0.02 to 0.04 every 4 to 12 h; and the initial air flow rate is 1 m³ / h. 3 / h~3m 3 / h, when the particle size D50 of the product is 2.8μm~3.2μm, increase the air flow rate by 0.4m. 3 / h~0.6m 3 / h.

[0041] Specifically, before the reaction, according to NiSO4, CoSO4 4、A mixed nickel-cobalt salt solution with a concentration of 1.8 mol / L to 2.4 mol / L was prepared using MnSO4 in a ratio of X:Y:Z, where X+Y+Z=1, 0.6≤X<1, 0<Y<0.4, and 0<Z<0.4. A 6 mol / L to 12 mol / L NaOH solution was prepared as a precipitant, and a 4 mol / L to 10 mol / L ammonia solution was prepared as a complexing agent. The ammonia concentration in the second reactor was controlled to be 1 g / L to 5 g / L. The co-precipitation reaction was first carried out under an inert atmosphere: the influent flow rate of the nickel-cobalt-manganese salt solution was 2 L / h to 4 L / h, the reaction temperature was 60℃ to 70℃, the reaction time was 4 h to 5 h, the pH value was 11.1 to 11.5, and the homogenization rate was 600 rpm to 700 rpm. The co-precipitation reaction was then carried out under an oxidizing atmosphere: the flow rate of the nickel-cobalt-manganese salt solution was increased by 0.5 L / h to 1 L / h every 4–12 h; the homogenization rate was decreased by 2 rpm to 10 rpm every 4–12 h; the reaction pH was decreased by 0.02 to 0.04 every 4–12 h; and the initial air flow rate was 1 m³ / h. 3 / h~3m 3 / h, when the particle size D50 of the product is 2.8μm~3.2μm, increase the air flow rate by 0.4m. 3 / h~0.6m 3 The reaction was stopped at a rate of 3.8 μm to 4.2 μm per hour, resulting in a high specific surface area, low sodium and sulfur ternary precursor with large interparticle gaps, high single-reactor yield, and uniform long-term growth rate.

[0042] In summary, by rationally controlling the ammonia concentration and pH value to regulate particle growth rate and reduce the inclusion of sodium and sulfur impurities within the particles during the reaction, and by controlling and adjusting the co-precipitation reaction parameters under an oxidizing atmosphere to improve particle size and thickness and control specific surface area, a high specific surface area and low sodium and sulfur ternary precursor was obtained, with a specific surface area of ​​18±2 m². 2 / g, tap density is 1.70±0.2g / cm³ 3 The particle size distribution has a diameter of 0.75±0.1, sodium content <70ppm, sulfur content <800ppm, and D50 of 4±0.2μm.

[0043] In a second aspect, the present invention provides a high specific surface area, low sodium and sulfur ternary precursor, which is obtained by the above-described method for preparing the high specific surface area, low sodium and sulfur ternary precursor.

[0044] A third aspect of the present invention provides a cathode material, wherein the cathode material is prepared by mixing the above-mentioned high specific surface area, low sodium and sulfur ternary precursor with a lithium source.

[0045] In a fourth aspect of the present invention, a lithium-ion battery is provided, wherein the positive electrode material of the lithium-ion battery is prepared by mixing the above-mentioned high specific surface area, low sodium and sulfur ternary precursor with a lithium source.

[0046] Example 1

[0047] A method for preparing a high specific surface area, low sodium and sulfur ternary precursor includes:

[0048] A 2.1 mol / L nickel-cobalt mixed salt solution was prepared according to a NiSO4:CoSO4:MnSO4 molar ratio of 60:10:30. A 10 mol / L NaOH solution was prepared as a precipitant, and an 8 mol / L ammonia solution was prepared as a complexing agent. Water was added to the first and second reaction vessels to the sampling port positions, and then stirring was performed and the jacket water of the reaction vessels was heated to 65°C. Ammonia solution was then injected into the first and second reaction vessels to prepare the pre-opening solution, and the ammonia concentration in both reaction vessels was controlled at 4 g / L.

[0049] Co-precipitation reaction in the first reactor: nitrogen gas flow rate 1.5 m³ / h 3 To ensure the synthesis reactor is under a nitrogen atmosphere, the homogenization speed is adjusted to 800 rpm. Simultaneously, the nickel-cobalt-manganese salt solution pump, sodium hydroxide solution pump, and ammonia solution pump are turned on to carry out the co-precipitation reaction. The salt feed rate is controlled at 5 L / h. After the feed, the temperature is stably controlled at 65℃, the ammonia concentration is 4 g / L, the pH value is 11.7, the particle size D50 is stably controlled at 1.2 μm~1.4 μm, and the solid content is 120 g / L~130 g / L. The sample obtained at this time is a primary particle with moderate thickness and large plate shape, and a secondary particle with more porous crystal nuclei.

[0050] Co-precipitation reaction in the second reactor: The material from the first reactor is pumped into the second reactor at a calculated flow rate of 15L. The stirring speed is adjusted to 600rpm. Then, the co-precipitation reaction is carried out simultaneously using pumps for nickel-cobalt-manganese salt solution, sodium hydroxide solution, and ammonia solution. The salt feed rate is controlled at 3L / h. After the feed, the temperature is stabilized at 65℃, the ammonia concentration is 4g / L, the initial pH is 11.3, and the nitrogen flow rate is 1.5m³. 3 After the reaction has proceeded for 4 hours, nitrogen gas will be introduced, then air will be introduced at a flow rate of 2.5 m³ / h. 3 Increase the salt flow rate by 0.6 L / h every 4 hours, decrease the stirring speed by 6 rpm, and decrease the reaction pH by 0.04. Once the particle size reaches 3 μm, adjust the air flow rate to 3 m³ / h. 3 / h, the reaction is stopped when the particle size reaches 4μm, and the product is aged, drained, alkali washed, water washed and dried to obtain a high specific surface area, low sodium and sulfur ternary precursor.

[0051] like Figure 1 As shown, the ternary precursor particles prepared in Example 1 have good sphericity, uniform primary particle growth, and moderate porosity.

[0052] The physical properties of the ternary precursor in Example 1 are as follows: specific surface area of ​​17.35 m². 2 / g, tap density is 1.68g / cm³ 3 The particle size distribution has a diameter of 0.76, a sodium content of 60 ppm, a sulfur content of 633 ppm, and a D50 of 3.98 μm.

[0053] Example 2

[0054] A method for preparing a high specific surface area, low sodium and sulfur ternary precursor includes:

[0055] A 2.1 mol / L nickel-cobalt mixed salt solution was prepared according to a NiSO4:CoSO4:MnSO4 molar ratio of 60:10:30. A 10 mol / L NaOH solution was prepared as a precipitant, and an 8 mol / L ammonia solution was prepared as a complexing agent. Water was added to the first and second reaction vessels to the sampling port positions, and then stirring was performed and the jacket water of the reaction vessels was heated to 65°C. Ammonia solution was then injected into the first and second reaction vessels to prepare the pre-opening solution, and the ammonia concentration in both reaction vessels was controlled at 4 g / L.

[0056] Co-precipitation reaction in the first reactor: nitrogen gas flow rate 1.5 m³ / h 3 To ensure the synthesis reactor is under a nitrogen atmosphere, the homogenization speed is adjusted to 800 rpm. Simultaneously, the nickel-cobalt-manganese salt solution pump, sodium hydroxide solution pump, and ammonia solution pump are turned on to carry out the co-precipitation reaction. The salt feed rate is controlled at 5 L / h. After the feed, the temperature is stably controlled at 65℃, the ammonia concentration is 4 g / L, the pH value is 11.8, the particle size D50 is stably controlled at 1.0 μm~1.2 μm, and the solid content is 120 g / L~130 g / L. The sample obtained at this time is a primary particle with moderate thickness and large plate shape, and a secondary particle with more porous crystal nuclei.

[0057] Co-precipitation reaction in the second reactor: The material from the first reactor is pumped into the second reactor at a calculated flow rate of 15L. The stirring speed is adjusted to 600rpm. Then, the co-precipitation reaction is carried out simultaneously using pumps for nickel-cobalt-manganese salt solution, sodium hydroxide solution, and ammonia solution. The salt feed rate is controlled at 3L / h. After the feed, the temperature is stabilized at 65℃, the ammonia concentration is 4g / L, the initial pH is 11.5, and the nitrogen flow rate is 1.5m³. 3 After 4 hours of reaction, nitrogen gas will be introduced, then air will be introduced at a flow rate of 2 m³ / h. 3 Increase the salt flow rate by 0.5 L / h every 4 hours, decrease the stirring speed by 3 rpm, and decrease the reaction pH by 0.03. Once the particle size reaches 3 μm, adjust the air flow rate to 2.5 m³ / h. 3 / h, the reaction is stopped when the particle size reaches 4μm, and the product is aged, drained, alkali washed, water washed and dried to obtain a high specific surface area, low sodium and sulfur ternary precursor.

[0058] like Figure 2 As shown, the ternary precursor particles prepared in Example 2 have good sphericity, and the primary particles are relatively thick with low porosity.

[0059] The physical properties of the ternary precursor in Example 2 are as follows: specific surface area of ​​16.51 m². 2 / g, tap density is 1.78g / cm³ 3 The particle size distribution has a diameter of 0.70, a sodium content of 68 ppm, a sulfur content of 656 ppm, and a D50 of 4.02 μm.

[0060] Example 3

[0061] A method for preparing a high specific surface area, low sodium and sulfur ternary precursor includes:

[0062] A 2.1 mol / L nickel-cobalt mixed salt solution was prepared according to a NiSO4:CoSO4:MnSO4 molar ratio of 60:10:30. A 10 mol / L NaOH solution was prepared as a precipitant, and an 8 mol / L ammonia solution was prepared as a complexing agent. Water was added to the first and second reaction vessels to the sampling port positions, and then stirring was performed and the jacket water of the reaction vessels was heated to 65°C. Ammonia solution was then injected into the first and second reaction vessels to prepare the pre-opening solution, and the ammonia concentration in both reaction vessels was controlled at 4 g / L.

[0063] Co-precipitation reaction in the first reactor: nitrogen gas flow rate 1.5 m³ / h 3 To ensure the synthesis reactor is under a nitrogen atmosphere, the homogenization speed is adjusted to 800 rpm. Simultaneously, the nickel-cobalt-manganese salt solution pump, sodium hydroxide solution pump, and ammonia solution pump are turned on to carry out the co-precipitation reaction. The salt feed rate is controlled at 5 L / h. After the feed, the temperature is stably controlled at 65℃, the ammonia concentration is 4 g / L, the pH value is 11.7, the particle size D50 is stably controlled at 1.2 μm~1.4 μm, and the solid content is 120 g / L~130 g / L. The sample obtained at this time is a primary particle with moderate thickness and large plate shape, and a secondary particle with more porous crystal nuclei.

[0064] Co-precipitation reaction in the second reactor: The material from the first reactor is pumped into the second reactor at a calculated flow rate of 15L. The stirring speed is adjusted to 600rpm. Then, the co-precipitation reaction is carried out simultaneously using pumps for nickel-cobalt-manganese salt solution, sodium hydroxide solution, and ammonia solution. The salt feed rate is controlled at 3L / h. After the feed, the temperature is stabilized at 65℃, the ammonia concentration is 4g / L, the initial pH is 11.1, and the nitrogen flow rate is 1.5m³. 3 After the reaction has proceeded for 4 hours, nitrogen gas will be introduced, then air will be introduced at a flow rate of 2.5 m³ / h. 3Increase the salt flow rate by 1 L / h every 4 hours, decrease the stirring speed by 10 rpm, and decrease the reaction pH by 0.02. Once the particle size reaches 3 μm, adjust the air flow rate to 3 m³ / h. 3 / h, the reaction is stopped when the particle size reaches 4μm, and the product is aged, drained, alkali washed, water washed and dried to obtain a high specific surface area, low sodium and sulfur ternary precursor.

[0065] like Figure 3 As shown, the ternary precursor particles prepared in Example 3 have good sphericity, but the primary particles are relatively thin and have high porosity.

[0066] The physical properties of the ternary precursor in Example 3 are as follows: specific surface area of ​​18.76 m². 2 / g, tap density is 1.54g / cm³ 3 The particle size distribution has a diameter of 0.78, a sodium content of 62 ppm, a sulfur content of 667 ppm, and a D50 of 4.05 μm.

[0067] Comparative Example 1

[0068] The difference between Comparative Example 1 and Example 1 is that the reaction temperature is different; the reaction temperature is adjusted from 65°C to 75°C. The coprecipitation reaction temperature in the first reactor of Comparative Example 1 is 75°C, and the coprecipitation reaction temperature in the second reactor of Comparative Example 1 is 75°C.

[0069] The physical properties of the ternary precursor in Comparative Example 1 are as follows: specific surface area is 20.35 m². 2 / g, tap density is 1.68g / cm³ 3 The particle size distribution has a diameter of 0.76, a sodium content of 80 ppm, a sulfur content of 983 ppm, and a D50 of 3.98 μm.

[0070] Comparative Example 2

[0071] The difference between Comparative Example 2 and Example 1 is that the initial pH value of the coprecipitation reaction in the second reactor is different; the initial pH value of Comparative Example 2 is 11.

[0072] The physical properties of the ternary precursor in Comparative Example 2 are as follows: specific surface area is 23.56 m². 2 / g, tap density is 1.42g / cm³ 3 The particle size distribution has a diameter of 0.81, a sodium content of 75 ppm, a sulfur content of 865 ppm, and a D50 of 4.03 μm.

[0073] Comparative Example 3

[0074] The difference between Comparative Example 3 and Example 1 is that the pH of the coprecipitation reaction in the first reactor is 11.9, resulting in crystal nuclei with a particle size D50 of 0.8 μm to 1.0 μm.

[0075] The physical properties of the ternary precursor in Comparative Example 3 are as follows: specific surface area is 14.22 m². 2 / g, tap density is 1.82g / cm³ 3 The particle size distribution has a diameter of 0.78, a sodium content of 78 ppm, a sulfur content of 832 ppm, and a D50 of 3.99 μm.

[0076] The ternary precursors prepared in Examples 1-3 and Comparative Examples 1-3 were mixed with lithium hydroxide and ball-milled for 4 hours to ensure homogeneity. The mixture was then heat-treated in a tube furnace at a heating rate of 1°C / min, first reaching 600°C and holding for 6 hours, then reaching 1000°C and holding for 8 hours. After natural cooling, the mixture was crushed, sieved, and surface-treated to obtain the ternary cathode material. The cathode material was then assembled with treated lithium metal anode sheets and lithium hexafluorophosphate electrolyte to form a lithium-ion battery. The performance of the lithium-ion battery was measured and is shown in Table 1 below.

[0077] Table 1

[0078] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Capacity / mAh / g 188 187 189 173 181 183 magnification 1C 1C 1C 1C 1C 1C First effect 89％ 87％ 88％ 82％ 85％ 84％ Voltage / V 2.8-4.25 2.8-4.25 2.8-4.25 2.8-4.25 2.8-4.25 2.8-4.25 Cycle performance / times 3200 3300 3100 2700 2900 2800

[0079] As can be seen from Table 1, the electrical performance of the ternary precursor materials in Examples 1-3 is superior to that in Comparative Examples 1-3. Under conditions of 2.8-4.25V and with a 1C / 1C charge / discharge regime, the initial coulombic efficiency of Examples 1-3 is above 85%, and they also have higher capacity and rate performance.

[0080] It will be readily understood by those skilled in the art that the above-described advantageous methods can be freely combined and superimposed without conflict. The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A method for preparing a high specific surface area, low sodium-sulfur ternary precursor, characterized in that, include: A nickel-cobalt-manganese salt solution, a precipitant, and a complexing agent were added to the first reactor, and a co-precipitation reaction was carried out under an inert atmosphere at a temperature of 60℃~70℃ and a pH of 11.6~11.8 to obtain crystal nuclei with a particle size D50 of 1.0μm~1.6μm; the ammonia concentration in the first reactor was controlled to be 1g / L~5g / L. The crystal nuclei, nickel-cobalt-manganese salt solution, precipitant, and complexing agent are added to the second reactor. Co-precipitation reaction is first carried out under an inert atmosphere, followed by co-precipitation reaction under an oxidizing atmosphere. The ammonia concentration in the second reactor is controlled to be 1 g / L to 5 g / L. The reaction is stopped when the product particle size D50 is 3.8 μm to 4.2 μm to obtain the high specific surface area, low sodium and sulfur ternary precursor. The coprecipitation reaction first carried out under an inert atmosphere includes: The initial nucleus content of the reaction is 120 g / L~130 g / L; The influent flow rate of the nickel-cobalt-manganese salt solution is 2 L / h to 4 L / h, and the influent concentration is 1.8 mol / L to 2.4 mol / L. The reaction temperature is 60℃~70℃, the reaction time is 4h~5h, the pH value is 11.1~11.5, and the homogenization rate is 600rpm~700rpm. The coprecipitation reaction under an oxidizing atmosphere includes: Increase the flow rate of the nickel-cobalt-manganese salt solution by 0.5 L / h to 1 L / h every 4 to 12 hours; Reduce the homogenization speed by 2 to 10 rpm every 4 to 12 hours; Decrease the reaction pH by 0.02-0.04 every 4-12 hours; The initial airflow rate is 1m 3 / h~3m 3 / h, when the particle size D50 of the product is 2.8μm~3.2μm, increase the air flow rate by 0.4m. 3 / h~0.6 m 3 / h; The high specific surface area and low sodium-sulfur ternary precursor has a specific surface area of ​​18±2m². 2 / g, particle size distribution with a diameter of 0.75±0.1, sodium content <70ppm, sulfur content <800ppm.

2. The method for preparing the high specific surface area, low sodium-sulfur ternary precursor according to claim 1, characterized in that, The coprecipitation reaction in the first reactor includes: The influent flow rate of the nickel-cobalt-manganese salt solution is 4 L / h to 6 L / h, and the influent concentration is 1.8 mol / L to 2.4 mol / L. The homogenization speed is 700 rpm to 800 rpm.

3. The method for preparing the high specific surface area, low sodium-sulfur ternary precursor according to claim 1, characterized in that, The precipitant is a sodium hydroxide solution with an influent concentration of 6 mol / L to 12 mol / L. The complexing agent is an ammonia solution with an influent concentration of 4 mol / L to 10 mol / L.

4. The method for preparing the high specific surface area, low sodium-sulfur ternary precursor according to claim 1, characterized in that, In the nickel-cobalt-manganese salt solution, the molar ratio of nickel, cobalt and manganese is X:Y:Z, satisfying X+Y+Z=1, and 0.6≤X<1, 0<Y<0.4 and 0<Z<0.

4.

5. The method for preparing the high specific surface area, low sodium-sulfur ternary precursor according to any one of claims 1 to 4, characterized in that, The high specific surface area, low sodium and sulfur ternary precursor has a tap density of 1.70 ± 0.2 g / cm³. 3 And D50 is 4±0.2μm.

6. A high specific surface area, low sodium and sulfur ternary precursor, characterized in that, It is obtained by the preparation method described in any one of claims 1 to 5.

7. A positive electrode material, characterized in that, The cathode material is prepared by mixing the high specific surface area, low sodium and sulfur ternary precursor described in claim 6 with a lithium source.

8. A lithium-ion battery, characterized in that, The positive electrode material of the lithium-ion battery is the positive electrode material as described in claim 7.

Images