Porous high specific surface nickel-cobalt-manganese ternary precursor and preparation method and application thereof

Abstract

The present invention relates to the technical field of lithium-ion batteries, and in particular, to a porous high-specific surface nickel cobalt manganese ternary precursor and its preparation method and application. The chemical formula of the porous high-specific surface nickel cobalt manganese ternary precursor is Ni x Co y Mn z (OH)2; wherein, 0.30 < x < 0.40, 0.35 < y < 0.40, 0.30 < z < 0.35, and x + y + z = 1; the specific surface area of the porous high-specific surface nickel cobalt manganese ternary precursor is 18-30 m 2 / g. The porous high-specific surface nickel cobalt manganese ternary precursor is porous and has a high specific surface area, and has excellent rate performance and cycling performance.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and in particular to a porous high-surface nickel-cobalt-manganese ternary precursor and a preparation method and application thereof. Background Art

[0002] In recent years, the new energy lithium battery industry has developed rapidly, especially ternary materials have received unprecedented development and attention. This is mainly due to its advantages of high capacity, good cyclability, and good rate performance. As the upper core material of ternary positive electrode materials, ternary precursors have a significant impact on the performance of positive electrode materials. For example, due to the lower specific surface area of ​​the precursor, the contact surface with the lithium source is smaller and the activity is lower, resulting in the obtained positive electrode material unable to meet the relevant charge and discharge rate performance requirements.

[0003] At present, the preparation of precursors usually adopts wet synthesis, that is, co-precipitation method: sulfate, chloride or nitrate of nickel, cobalt and manganese is used as the raw material of metal liquid, sodium hydroxide solution or sodium carbonate solution is used as precipitant, and ammonia water is used as complexing agent to achieve the purpose of co-precipitation.

[0004] For example, patent CN113735191A discloses a porous structure ternary precursor and its preparation method. The co-precipitation method is adopted to first prepare a certain amount of small lithium carbonate particles, and then the ternary precursor will wrap some of the small lithium carbonate particles inside it during its growth process; carbon dioxide is introduced and the pH is adjusted to generate lithium bicarbonate that is easily soluble in water. The dissolution of lithium carbonate causes a porous structure to be produced inside the ternary precursor, thereby obtaining the corresponding precursor product.

[0005] However, the invention patent has many processes and complicated process control. The primary particles obtained are 5-10nm thick, hollow inside and dense around. The precursor surface area is relatively low (BET = 17.15m 2 / g), which is not conducive to the contact between the ternary positive electrode material and the electrolyte after sintering, resulting in reduced lithium ion transmission efficiency and rate performance.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The first object of the present invention is to provide a porous high specific surface area nickel-cobalt-manganese ternary precursor, which has the advantages of high specific surface area, looseness and porosity, thereby improving the lithium ion transmission efficiency and rate performance.

[0008] The second purpose of the present invention is to provide a method for preparing the porous high specific surface area nickel-cobalt-manganese ternary precursor, which has the advantages of simple process, short flow, easy control, and the prepared porous high specific surface area nickel-cobalt-manganese ternary precursor is loose and porous and has a high specific surface area.

[0009] The third object of the present invention is to provide a cathode material for lithium ion batteries.

[0010] The fourth object of the present invention is to provide a positive electrode sheet.

[0011] The fifth object of the present invention is to provide a lithium ion battery.

[0012] In order to achieve the above objects of the present invention, the following technical solutions are specifically adopted:

[0013] In the first aspect, the present invention provides a porous high specific surface nickel cobalt manganese ternary precursor, and the chemical formula of the porous high specific surface nickel cobalt manganese ternary precursor is Ni x Co y Mn z (OH) 2 .

[0014] Wherein, 0.30 < x < 0.40, 0.35 < y < 0.40, 0.30 < z < 0.35, and x + y + z = 1.

[0015] The x in the above chemical formula includes, but is not limited to, any point value of 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39 or the range value between any two of them. The y in the above chemical formula includes, but is not limited to, any point value of 0.36, 0.37, 0.38, 0.39 or the range value between any two of them. The z in the above chemical formula includes, but is not limited to, any point value of 0.31, 0.32, 0.33, 0.34 or the range value between any two of them.

[0016] The specific surface area of the porous high specific surface nickel cobalt manganese ternary precursor is 18 - 30 m 2 / g, including, but not limited to, 19 m 2 / g, 20 m 2 / g, 21 m 2 / g, 22 m 2 / g, 23 m 2 / g, 24 m 2 / g, 25 m 2 / g, 26 m 2 / g, 27 m 2 / g, 28 m 2 / g, 29 m 2 / g or any point value between any two of them or the range value between any two of them.

[0017] The porous high specific surface area nickel-cobalt-manganese ternary precursor provided by the present invention is loose and porous and has a high specific surface area, which can solve the problem of fewer active sites for reaction with lithium sources during sintering, thereby obtaining a positive electrode material with good rate performance and cycle performance.

[0018] Among them, the loose and porous morphology is conducive to the infiltration (wetting) of the electrolyte, thereby shortening the lithium ion transmission channel.

[0019] Preferably, the porous high-specific nickel-cobalt-manganese ternary precursor comprises porous secondary particles formed by cross-arrangement and agglomeration of primary particles. The shape of the primary particles includes flakes, and the thickness of the primary particles is 1 to 2 nm, including but not limited to any point value of 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, 1.5 nm, 1.6 nm, 1.7 nm, 1.8 nm, 1.9 nm or any range value between two of them.

[0020] The primary particles prepared by the present invention are in the form of thin sheets, which can effectively improve the material specific surface area, increase the reaction sites in the sintering process, facilitate the preparation of single crystal materials, and thus improve the rate performance and cycle performance of the materials.

[0021] In some specific embodiments of the present invention, the length of the primary particle is 15 to 40 nm, including but not limited to any point value of 17 nm, 19 nm, 20 nm, 23 nm, 25 nm, 28 nm, 30 nm, 33 nm, 35 nm, 38 nm or a range value between any two of them.

[0022] Preferably, the shape of the secondary particles includes spheres and / or quasi-spheres, and the D50 particle size of the secondary particles is 3 to 5 μm, including but not limited to any point value of 3.2 μm, 3.5 μm, 3.8 μm, 4 μm, 4.2 μm, 4.5 μm, 4.8 μm or a range value between any two of them.

[0023] In a second aspect, the present invention provides a method for preparing the porous high specific surface area nickel-cobalt-manganese ternary precursor as described above, comprising the following steps:

[0024] Under an inert atmosphere, a nickel-cobalt-manganese ternary salt solution, a precipitant solution, and a complexing agent solution are added to a reaction vessel containing a base solution to perform a coprecipitation reaction;

[0025] When the D50 particle size of the particles in the reaction container is 1.5-2.5 μm (including but not limited to any one of 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2.0 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm or a range between any two of them), oxygen-containing gas is introduced so that the volume fraction of oxygen in the reaction container is 3%-10% (including but not limited to any one of 4%, 5%, 6%, 7%, 8%, 9% or a range between any two of them).

[0026] In some specific embodiments of the present invention, the oxygen-containing gas includes air and / or oxygen, preferably air, which is easier to control the dosage.

[0027] When the particles in the reaction container reach the target particle size, the reaction is stopped and the air is stopped, and then solid-liquid separation, drying, screening and demagnetization are carried out in sequence to obtain the porous high-specific surface area nickel-cobalt-manganese ternary precursor. When the particles in the reaction container reach the target particle size, the air is stopped to avoid problems such as morphology not meeting the requirements, too thin, stratification and deformation, and to avoid excessive oxidation resulting in excessive specific surface area.

[0028] The preparation method of the porous high specific surface area nickel-cobalt-manganese ternary precursor provided by the present invention has a short process, simple operation, and easy control. In addition, by introducing a specific amount of air within a specific particle size range, the obtained secondary particles are made loose and porous, which can better improve the specific surface area of ​​the precursor, thereby solving the problem of fewer active sites for reaction with the lithium source during the sintering process, and obtaining a positive electrode material with high rate performance and good cycle performance.

[0029] Preferably, the molar concentration of metal ions in the nickel-cobalt-manganese ternary salt solution is 1 to 2.5 mol / L, including but not limited to any one of 1.2 mol / L, 1.5 mol / L, 1.8 mol / L, 2.0 mol / L, 2.3 mol / L or a range between any two of them.

[0030] In some specific embodiments of the present invention, the metal ions in the nickel-cobalt-manganese ternary salt solution include nickel ions, cobalt ions and manganese ions. The nickel ions are mainly provided by soluble nickel salts, such as nickel sulfate, nickel nitrate, etc., but not limited thereto; the cobalt ions are mainly provided by soluble cobalt salts, such as cobalt sulfate, cobalt nitrate, etc., but not limited thereto; the manganese ions are mainly provided by soluble manganese salts, such as manganese sulfate, manganese nitrate, etc., but not limited thereto.

[0031] In some specific embodiments of the present invention, the molar ratio of nickel ions, cobalt ions, and manganese ions in the nickel-cobalt-manganese ternary salt solution is x:y:z, where 0.30 < x < 0.40, 0.35 < y < 0.40, 0.30 < z < 0.35, and x + y + z = 1.

[0032] In some specific embodiments of the present invention, the method for preparing the nickel-cobalt-manganese ternary salt solution includes: weighing soluble nickel salt, soluble cobalt salt, and soluble manganese salt according to the molar ratio of nickel element, cobalt element, and manganese element in the required porous high specific surface nickel-cobalt-manganese ternary precursor and the required molar concentration, and then dissolving them in water to obtain the nickel-cobalt-manganese ternary salt solution.

[0033] Preferably, the precipitant solution includes at least one of sodium hydroxide solution, potassium hydroxide solution, sodium carbonate solution, and potassium carbonate solution; more preferably, the molar concentration of the precipitant solution is 8 - 15 mol / L; including but not limited to the point value of any one of 9 mol / L, 10 mol / L, 11 mol / L, 12 mol / L, 13 mol / L, 14 mol / L or the range value between any two of them.

[0034] Preferably, the complexing agent solution includes ammonia water; more preferably, the mass concentration of ammonium ions in the ammonia water is 150 - 200 g / L, including but not limited to the point value of any one of 155 g / L, 160 g / L, 165 g / L, 170 g / L, 175 g / L, 180 g / L, 185 g / L, 190 g / L, 195 g / L or the range value between any two of them.

[0035] In some specific embodiments of the present invention, the inert atmosphere includes nitrogen atmosphere and / or argon atmosphere.

[0036] Preferably, the mass concentration of ammonium ions in the bottom liquid is 4 - 5 g / L; including but not limited to the point value of any one of 4.2 g / L, 4.4 g / L, 4.5 g / L, 4.7 g / L, 4.9 g / L or the range value between any two of them.

[0037] In some specific embodiments of the present invention, the bottom liquid is mainly prepared from a complexing agent solution, an alkaline compound, and deionized water. Among them, the alkaline compound includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate.

[0038] Preferably, the pH of the bottom liquid is 11.5 - 12.5, including but not limited to the point value of any one of 11.7, 11.9, 12.0, 12.2, 12.4 or the range value between any two of them.

[0039] The temperature of the base liquid is 50-60°C, including but not limited to any point value of 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C or a range value between any two of them.

[0040] Preferably, during the coprecipitation reaction, the mass concentration of ammonium ions in the mixed material is 4-5 g / L; including but not limited to any one of 4.2 g / L, 4.4 g / L, 4.5 g / L, 4.7 g / L, 4.9 g / L or a range between any two of them.

[0041] Preferably, during the coprecipitation reaction, the temperature of the mixed material is 50-60°C, including but not limited to any one of 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C or a range between any two of them.

[0042] In some specific embodiments of the present invention, during the coprecipitation reaction, the mixed material is stirred at a rotation speed of 200 to 300 rpm.

[0043] In some specific embodiments of the present invention, the gas flow rate of the inert atmosphere is 300-600 L / h, including but not limited to any point value of 350 L / h, 400 L / h, 450 L / h, 500 L / h, 550 L / h or a range value between any two of them.

[0044] Preferably, during the coprecipitation reaction, the pH of the mixed material is 10.5-12.5, including but not limited to any one of 10.7, 10.9, 11, 11.2, 11.4, 11.5, 11.7, 11.9, 12, 12.2, 12.4 or a range between any two of them.

[0045] In some specific embodiments of the present invention, after adding the nickel-cobalt-manganese ternary salt solution, the precipitant solution, and the complexing agent solution to the reaction vessel containing the base solution, the pH of the mixture is adjusted to 11.5 to 12.5, and then reacted for 30 to 60 minutes, and then the pH of the mixture is adjusted to 10.5 to 11.0. This is conducive to the growth of seed crystals.

[0046] In some specific embodiments of the present invention, the coprecipitation reaction is carried out in a reactor, and the reactor includes a main reactor and a secondary reactor that are interconnected. After a period of reaction, when the liquid level of the main reactor reaches the overflow port, the main reactor is opened to overflow to the secondary reactor, and the main and secondary cycles are opened during this period (coprecipitation reaction is carried out by intermittent method), and the gas flow rate of the inert atmosphere of the main reactor and the secondary reactor is ensured to be maintained at 300 to 600 L / h. Among them, the main reactor is mainly used for the main reaction, the secondary reactor is mainly used for aging, and the overflow is carried out for the main and secondary cycles, which can ensure that the material is evenly distributed and the particle size is uniform.

[0047] In some specific embodiments of the present invention, the target particle size is D50=3-5 μm, including but not limited to any point value of 3.2 μm, 3.5 μm, 3.8 μm, 4 μm, 4.2 μm, 4.5 μm, 4.8 μm or a range value between any two of them.

[0048] In some specific embodiments of the present invention, during the process of stopping the reaction and stopping the introduction of air, the reaction system is kept in an inert atmosphere.

[0049] In some specific embodiments of the present invention, after the solid-liquid separation and before the drying, the method further includes washing with a sodium hydroxide solution with a mass concentration of 50 to 100 g / L and then rinsing with pure water at a temperature of 60 to 80° C. for 2 to 3 times, wherein the washing time is 60 to 120 min.

[0050] In some specific embodiments of the present invention, the drying temperature is 120-150° C., and the drying time is 5-10 hours.

[0051] In a third aspect, the present invention provides a lithium-ion battery positive electrode material, which is mainly prepared from the porous high-specific surface area nickel-cobalt-manganese ternary precursor as described above, or the porous high-specific surface area nickel-cobalt-manganese ternary precursor prepared by the preparation method of the porous high-specific surface area nickel-cobalt-manganese ternary precursor as described above.

[0052] In a fourth aspect, the present invention provides a positive electrode plate, which is mainly made of the lithium-ion battery positive electrode material as described above.

[0053] In a fifth aspect, the present invention provides a lithium-ion battery comprising the positive electrode plate as described above.

[0054] The lithium-ion battery has excellent electrochemical performance, especially high rate performance and good cycle performance.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] (1) The porous high specific surface area nickel-cobalt-manganese ternary precursor provided by the present invention is loose and porous, and has a high specific surface area, which improves the rate performance and cyclability.

[0057] (2) The method for preparing the porous high specific surface area nickel-cobalt-manganese ternary precursor provided by the present invention has the advantages of short process, simple operation and easy control.

[0058] (3) The method for preparing a porous high-specific surface area nickel-cobalt-manganese ternary precursor provided by the present invention makes the secondary particles loose and porous by introducing a specific amount of air within a specific particle size range, which can effectively improve the specific surface area of ​​the precursor and solve the problem of few active sites for reaction with the lithium source during the sintering process, thereby obtaining a positive electrode material with high rate performance and good cycle performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0060] Figure 1 This is a SEM image of the porous high surface area ratio nickel-cobalt-manganese ternary precursor provided in Example 1 of the present invention at a magnification of 5000 times;

[0061] Figure 2 This is a SEM image of the porous high surface area ratio nickel-cobalt-manganese ternary precursor provided in Example 1 of the present invention at a magnification of 10,000 times;

[0062] Figure 3 This is a SEM image of the porous high surface area ratio nickel-cobalt-manganese ternary precursor provided in Example 2 of the present invention at a magnification of 5000 times;

[0063] Figure 4 This is a SEM image of the porous high surface area ratio nickel-cobalt-manganese ternary precursor provided in Example 2 of the present invention at a magnification of 10,000 times;

[0064] Figure 5 This is a SEM image of the porous high-surface-to-surface nickel-cobalt-manganese ternary precursor provided in Example 3 of the present invention at a magnification of 5000 times;

[0065] Figure 6 This is a SEM image of the porous high surface area ratio nickel-cobalt-manganese ternary precursor provided in Example 3 of the present invention at a magnification of 10,000 times;

[0066] Figure 7 A cross-sectional CP-SEM image of the porous high surface area ratio nickel-cobalt-manganese ternary precursor provided in Example 3 of the present invention at a magnification of 5000 times;

[0067] Figure 8 This is a cross-sectional CP-SEM image of the porous high surface area specific nickel-cobalt-manganese ternary precursor provided in Example 3 of the present invention at a magnification of 10,000 times. DETAILED DESCRIPTION

[0068] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0069] Example 1

[0070] This embodiment provides a method for preparing a porous high specific surface area nickel-cobalt-manganese ternary precursor, comprising the following steps:

[0071] (1) Nickel sulfate, cobalt sulfate and manganese sulfate are used to prepare a nickel-cobalt-manganese ternary salt solution with a total metal ion concentration of 2 mol / L (120 g / L), wherein the molar ratio of nickel ion, cobalt ion and manganese ion is 0.325:0.365:0.31. A sodium hydroxide solution with a concentration of 10 mol / L is also prepared, and ammonia water with a mass concentration of ammonium ions of 180 g / L is prepared.

[0072] (2) Nitrogen was introduced into the sealed main reactor and the secondary reactor at a flow rate of 500 L / h for 5 hours. During this period, 200 L of deionized water was added to the main reactor to cover the middle layer and stirred. The stirring was turned on at 270 rpm and the reaction temperature (temperature of the material in the main reactor) was controlled at 60°C.

[0073] (3) Add ammonia water to the main reactor to prepare a base liquid, control the mass concentration of ammonium ions in the base liquid to 5.0 g / L, and add alkali solution (sodium hydroxide solution) to adjust the pH of the base liquid to 12.5.

[0074] (4) Add nickel-cobalt-manganese ternary salt solution, sodium hydroxide solution and ammonia water to the main reactor at the same time. During this period, the pH of the system (materials in the main reactor) is maintained at 12.5, the mass concentration of ammonium ions is 5.0 g / L, the nitrogen flow rate is 500 L / h, and the reaction time of this stage is 60 min. Then, the pH of the system (materials in the main reactor) is reduced to 11.0 to allow the particles to grow further.

[0075] After a certain reaction time, when the liquid level of the main reactor reaches the overflow port, the main reactor is opened to overflow to the secondary reactor, during which the main and secondary cycles are opened, and the nitrogen flow rate of the main reactor and the secondary reactor is ensured to be 500L / h.

[0076] (5) When the particle size of the particles in the main reactor reaches D50 = 2.5 μm, air is introduced into the main reactor to control the volume fraction of oxygen in the main reactor to 4.8%.

[0077] When the particles in the main reactor react to a particle size of D50 = 3.0 μm, the machine is stopped to discharge the material and stop introducing air.

[0078] (6) After solid-liquid separation, the slurry after the reaction was washed twice with a sodium hydroxide solution with a concentration of 60 g / L, and then rinsed three times with pure water at a temperature of 70°C.

[0079] (7) The washed ternary precursor filter cake was placed in an oven at 130°C for drying for 5 hours. After the moisture content was qualified, it was sieved and demagnetized to obtain a porous high-specific surface area nickel-cobalt-manganese ternary precursor. After testing, its BET was 20.73m 2 / g.

[0080] like Figure 1 and Figure 2 The following are SEM images of the porous high-surface-to-surface nickel-cobalt-manganese ternary precursor prepared in this embodiment at different magnifications. Figure 1 The magnification is 5000 times. Figure 2 The magnification is 10,000 times.

[0081] Example 2

[0082] The method for preparing the porous high specific surface area nickel-cobalt-manganese ternary precursor provided in this embodiment comprises the following steps:

[0083] (1) Nickel sulfate, cobalt sulfate and manganese sulfate are used to prepare a nickel-cobalt-manganese ternary salt solution with a total metal ion concentration of 2 mol / L (120 g / L), wherein the molar ratio of nickel ion, cobalt ion and manganese ion is 0.325:0.365:0.31. A sodium hydroxide solution with a concentration of 10 mol / L is also prepared, and ammonia water with a mass concentration of ammonium ions of 180 g / L is prepared.

[0084] (2) Nitrogen was introduced into the sealed main reactor and the secondary reactor at a flow rate of 500 L / h for 5 hours. During this period, deionized water was added to cover the middle layer and stirred at 250 rpm. The reaction temperature (material temperature in the main reactor) was controlled at 50°C.

[0085] (3) Add ammonia water to the main reactor to prepare a base solution, control the mass concentration of ammonium ions in the base solution to 4 g / L, and add alkali solution (sodium hydroxide solution) to adjust the pH of the base solution to 11.5.

[0086] (4) Add nickel-cobalt-manganese ternary salt solution, sodium hydroxide solution and ammonia water to the main reactor at the same time. During this period, the pH of the system (the material in the main reactor) is maintained at 11.5, the mass concentration of ammonium ions is 4.0 g / L, the nitrogen flow rate is 500 L / h, and the reaction time of this stage is 30 min. Then, the pH of the system (the material in the main reactor) is reduced to 10.5 to allow the particles to grow further.

[0087] After a certain reaction time, when the liquid level of the main reactor reaches the overflow port, the main reactor is opened to overflow to the secondary reactor, during which the main and secondary cycles are opened, and the nitrogen flow rate of the main reactor and the secondary reactor is ensured to be 500L / h.

[0088] (5) When the particle size of the particles in the main reactor reaches D50 = 1.5 μm, air is introduced into the main reactor to control the volume fraction of oxygen in the main reactor to 5.0%.

[0089] When the particles in the main reactor react to a particle size of D50 = 3.1 μm, the machine is stopped to discharge the material and stop introducing air.

[0090] (6) After solid-liquid separation, the slurry after the reaction was washed twice with a sodium hydroxide solution with a concentration of 60 g / L, and then rinsed three times with pure water at a temperature of 70°C.

[0091] (7) The washed ternary precursor filter cake was placed in an oven at 130°C for drying for 5 hours. After the moisture content was qualified, it was sieved and demagnetized to obtain a porous high-specific surface area nickel-cobalt-manganese ternary precursor. After testing, its BET was 21.25m 2 / g.

[0092] like Figure 3 and Figure 4 The following are SEM images of the porous high-surface-to-surface nickel-cobalt-manganese ternary precursor prepared in this embodiment at different magnifications. Figure 3 The magnification is 5000 times. Figure 4 The magnification is 10,000 times.

[0093] Example 3

[0094] The method for preparing the porous high specific surface area nickel-cobalt-manganese ternary precursor provided in this embodiment comprises the following steps:

[0095] (1) Nickel sulfate, cobalt sulfate and manganese sulfate are used to prepare a nickel-cobalt-manganese ternary salt solution with a total metal ion concentration of 2 mol / L (120 g / L), wherein the molar ratio of nickel ion, cobalt ion and manganese ion is 0.325:0.365:0.31. A sodium hydroxide solution with a concentration of 10 mol / L is also prepared, and ammonia water with a mass concentration of ammonium ions of 180 g / L is prepared.

[0096] (2) Nitrogen was introduced into the sealed main reactor and the secondary reactor at a flow rate of 500 L / h for 5 hours. During this period, deionized water was added to cover the middle layer and stirred at 250 rpm. The reaction temperature (material temperature in the main reactor) was controlled at 55°C.

[0097] (3) Add ammonia water to the main reactor to prepare a base liquid, control the mass concentration of ammonium ions in the base liquid to 4.5 g / L, and add alkali solution (sodium hydroxide solution) to adjust the pH of the base liquid to 12.

[0098] (4) Add nickel-cobalt-manganese ternary salt solution, sodium hydroxide solution and ammonia water to the main reactor at the same time. During this period, the pH of the system (materials in the main reactor) is maintained at 12, the mass concentration of ammonium ions is 4.5 g / L, the nitrogen flow rate is 500 L / h, and the reaction time of this stage is 45 min. Then, the pH of the system (materials in the main reactor) is reduced to 10.8 to allow the particles to grow further.

[0099] After a certain reaction time, when the liquid level of the main reactor reaches the overflow port, the main reactor is opened to overflow to the secondary reactor, during which the main and secondary cycles are opened, and the nitrogen flow rate of the main reactor and the secondary reactor is ensured to be 500L / h.

[0100] (5) When the particle size of the particles in the main reactor reaches D50 = 2 μm, air is introduced into the main reactor to control the volume fraction of oxygen in the main reactor to 5.1%.

[0101] When the particles in the main reactor react to a particle size of D50 = 3.2 μm, the machine is stopped to discharge the material and stop introducing air.

[0102] (6) After solid-liquid separation, the slurry after the reaction was washed twice with a sodium hydroxide solution with a concentration of 60 g / L, and then rinsed three times with pure water at a temperature of 70°C.

[0103] (7) The washed ternary precursor filter cake was placed in an oven at 130°C for drying for 5 hours. After the moisture content was qualified, it was sieved and demagnetized to obtain a porous high-specific surface area nickel-cobalt-manganese ternary precursor. After testing, its BET was 21.81m 2 / g.

[0104] like Figure 5 and Figure 6The following are SEM images of the porous high-surface-to-surface nickel-cobalt-manganese ternary precursor prepared in this embodiment at different magnifications. Figure 5 The magnification is 5000 times. Figure 6 The magnification is 10,000 times.

[0105] In order to better observe the internal structure of the secondary agglomerate particles, the porous high surface area nickel-cobalt-manganese ternary precursor prepared in this embodiment was subjected to CP analysis. Figure 7 and Figure 8 The cross-sectional CP-SEM image of the porous high specific surface area nickel-cobalt-manganese ternary precursor prepared in this embodiment is shown. Figure 7 The magnification is 5000 times. Figure 8 The magnification is 10,000 times.

[0106] Comparative Example 1

[0107] The preparation method of the precursor provided in this comparative example is basically the same as that in Example 3, except that in step (5), when the particles in the main reactor reach a particle size of D50 = 1.0 μm, air is introduced into the main reactor.

[0108] Comparative Example 2

[0109] The preparation method of the precursor provided in this comparative example is basically the same as that of Example 3, except that in step (5), when the particles in the main reactor reach a particle size of D50 = 4 μm, air is introduced into the main reactor.

[0110] Comparative Example 3

[0111] The preparation method of the precursor provided in this comparative example is basically the same as that of Example 3, except that in step (5), the volume fraction of oxygen in the main reactor is controlled to be 1%.

[0112] Comparative Example 4

[0113] The preparation method of the precursor provided in this comparative example is basically the same as that of Example 3, except that in step (5), the volume fraction of oxygen in the main reaction kettle is controlled to be 15%.

[0114] Experimental Example 1

[0115] The key physical and chemical indicators of the precursors prepared in the above embodiments and comparative examples are shown in Table 1 below.

[0116] Table 1 Key physical and chemical indicators of the precursors prepared in each group

[0117]

[0118]

[0119] By comparing the experimental data of Example 3 and Comparative Example 1, it can be seen that in Comparative Example 1, due to the early oxygen-passing time, the degree of oxidation of the material is aggravated, the primary particles are thinner (ie, the thickness is reduced), and the specific surface area becomes larger.

[0120] By comparing the experimental data of Example 3 and Comparative Example 2, it can be seen that in Comparative Example 2, due to the delayed time of introducing air, the degree of oxidation is insufficient, the primary particles are thicker, and the specific surface area is lower.

[0121] By comparing the experimental data of Example 3 and Comparative Example 3, it can be seen that in Comparative Example 3, due to the reduction in the volume fraction of oxygen, the degree of oxidation is insufficient, the primary particles are thicker, and the specific surface area is lower.

[0122] By comparing the experimental data of Example 3 and Comparative Example 4, it can be seen that in Comparative Example 4, due to the excessively high oxygen content, excessive oxidation occurs, the primary particles are thin and brittle, and the specific surface area is too high.

[0123] Although the present invention has been illustrated and described with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents without departing from the spirit and scope of the present invention. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A method for preparing a porous high specific surface area nickel-cobalt-manganese ternary precursor, characterized in that: The steps include: Under an inert atmosphere, a nickel-cobalt-manganese ternary salt solution, a precipitant solution, and a complexing agent solution are added to a reaction vessel containing a base solution to perform a coprecipitation reaction; When the particle size D50 of the particles in the reaction container is 1.5-2.5 μm, introducing oxygen-containing gas so that the volume fraction of oxygen in the reaction container is 3%-10%; When the particles in the reaction container reach the target particle size, the reaction is stopped and the air is stopped, and then solid-liquid separation, drying, sieving and demagnetization are performed in sequence to obtain the porous high-surface nickel-cobalt-manganese ternary precursor; The chemical formula of the porous high specific surface nickel cobalt manganese ternary precursor is Ni x Co y Mn z (OH)2; wherein, 0.30 < x < 0.40, 0.35 < y < 0.40, 0.30 < z < 0.35, and x + y + z = 1; The specific surface area of ​​the porous high specific surface area nickel-cobalt-manganese ternary precursor is 20.73-30m 2 / g; The porous high-specific surface area nickel-cobalt-manganese ternary precursor includes secondary particles formed by cross-arranged and agglomerated primary particles; wherein the shape of the primary particles includes flakes, the thickness of the primary particles is 1-2 nm, and the length of the primary particles is 15-40 nm; the D50 particle size of the secondary particles is 3-5 μm.

2. The method for preparing a porous high specific surface area nickel-cobalt-manganese ternary precursor according to claim 1, characterized in that: The molar concentration of metal ions in the nickel-cobalt-manganese ternary salt solution is 1-2.5 mol / L.

3. The method for preparing a porous high specific surface area nickel-cobalt-manganese ternary precursor according to claim 1, characterized in that: The precipitant solution comprises at least one of a sodium hydroxide solution, a potassium hydroxide solution, a sodium carbonate solution and a potassium carbonate solution; and / or the molar concentration of the precipitant solution is 8-15 mol / L.

4. The method for preparing a porous high specific surface area nickel-cobalt-manganese ternary precursor according to claim 1, characterized in that: The complexing agent solution includes ammonia water; and / or the mass concentration of ammonium ions in the ammonia water is 150-200 g / L.

5. The method for preparing a porous high specific surface area nickel-cobalt-manganese ternary precursor according to claim 1, characterized in that: The mass concentration of ammonium ions in the base solution is 4-5 g / L.

6. The method for preparing a porous high specific surface area nickel-cobalt-manganese ternary precursor according to claim 1, characterized in that: The pH of the base liquid is 11.5-12.5, and the temperature of the base liquid is 50-60°C.

7. The method for preparing a porous high specific surface area nickel-cobalt-manganese ternary precursor according to claim 1, characterized in that: During the coprecipitation reaction, the mass concentration of ammonium ions in the mixed material is 4-5 g / L; And / or, during the coprecipitation reaction, the temperature of the mixed material is 50-60°C.

8. The method for preparing a porous high specific surface area nickel-cobalt-manganese ternary precursor according to claim 1, characterized in that: During the coprecipitation reaction, the pH of the mixed material is 10.5-12.

5.

9. A porous high surface specific nickel-cobalt-manganese ternary precursor prepared by the method for preparing a porous high surface specific nickel-cobalt-manganese ternary precursor according to any one of claims 1 to 8.

10. The porous high specific surface area nickel-cobalt-manganese ternary precursor according to claim 9, characterized in that: The porous high-surface-weight nickel-cobalt-manganese ternary precursor includes secondary particles formed by cross-arrangement and agglomeration of primary particles, and the shapes of the secondary particles include spherical and / or quasi-spherical shapes.

11. A positive electrode material for a lithium-ion battery, characterized in that: The porous high surface ratio nickel-cobalt-manganese ternary precursor is mainly prepared by the method for preparing the porous high surface ratio nickel-cobalt-manganese ternary precursor according to any one of claims 1 to 8, or the porous high surface ratio nickel-cobalt-manganese ternary precursor according to any one of claims 9 to 10.

12. A positive electrode sheet, characterized in that: It is mainly made from the lithium-ion battery positive electrode material according to claim 11.

13. A lithium ion battery, characterized in that Comprising the positive electrode sheet as described in claim 12.

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