Method for producing positive electrode active material precursor

Abstract

A method of manufacturing a positive active material precursor using a batch reactor according to the present disclosure, the method comprising the steps of: (S1) forming a core of the precursor; (S2) growing the core formed in step S1; (S3) further growing the core grown in step S2; and (S4) further growing the nucleus grown in step S3, where the stirring speed in the batch reactor is set to: 200 rpm to 900 rpm during step S2, 800 rpm or less during step S3, and 700 rpm or less during step S4, and the reaction solution is designed to overflow when the batch reactor is full thereof.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a method for manufacturing a positive electrode active material precursor, and more particularly, to a method for manufacturing a positive electrode active material precursor in an overflow manner using a batch reactor. BACKGROUND

[0002] In recent years, as the market for battery electric vehicles (BEVs) expands, the demand for secondary batteries has been increasing. A battery generally includes a cathode, an anode, an electrolyte, and a separator, wherein the cathode and the anode contain an active material capable of intercalating and deintercalating lithium ions, for example.

[0003] In a method for manufacturing a positive electrode active material precursor, there are a typical continuous method using a continuous stirred-tank reactor (CSTR) and a batch method using a batch-type reactor. The continuous method includes co-precipitating raw materials and simultaneously discharging particles formed as a precursor, while the batch method includes introducing raw materials into a reactor volume to react for a certain period of time, and then discharging the precursor after the reaction is completed.

[0004] In a batch reactor, as the co-precipitation reaction time progresses, fine particles of the precursor are formed. In order to form a certain size of the precursor particles, it is necessary to continue the growth of the fine particles formed by the initial nucleation reaction.

[0005] However, during the growth reaction of the precursor fine particles, new nucleation reactions continuously occur, so that small-sized precursor particles are continuously generated. Therefore, at the end of the co-precipitation reaction time, the average particle size of the precursor particles becomes smaller and the particle size distribution becomes non-uniform. Ultimately, the tap density, specific surface area, and other physical properties of the desired positive electrode active material do not meet the target values, adversely affecting the charge / discharge capacity performance of the battery.

[0006] To solve these problems, the influence of precursor fine particles is controlled in the prior art in which fine particles generated during a grinding process using an Air Classifier Mill (ACM), an Air Jet Mill, etc. are captured by a separate back filter or removed by transferring a reaction solution containing a precursor from a reactor to a cyclone facility and centrifugally separating the fine particles. However, such prior art increases costs and total process time due to additional processes / equipment, resulting in decreased production efficiency of a positive active material and a reduction in production efficiency (line of balance (LOB)).

[0007] In a precursor manufacturing process, a problem that occurs as the average particle diameter of a precursor particle increases is surface cracking due to particle collision. When a crack occurs on the surface of a precursor particle, the press density decreases, which can cause additional cracking during an electrode rolling process in the manufacture of a positive active material. Accordingly, a side reaction with an electrolyte can occur, resulting in a decrease in battery performance. SUMMARY

[0008] The present disclosure aims to solve the above problems and provide a method for manufacturing a precursor in which the formation of precursor fine particles is minimized during the growth period of a precursor nucleus to achieve a uniform particle size distribution, thereby preventing cracks from occurring on the surface of a precursor particle.

[0009] According to one aspect of the present disclosure, a method of manufacturing a positive active material precursor using a batch reactor includes the steps of: (S1) forming a nucleus of a precursor; (S2) growing the nucleus formed in step S1; (S3) further growing the nucleus grown in step S2; and (S4) further growing the nucleus grown in step S3, wherein the stirring speed in the batch reactor is set to 200 rpm to 900 rpm during step S2, 800 rpm or less during step S3, and 700 rpm or less during step S4, and the reaction solution is designed to overflow when the batch reactor is full thereof.

[0010] According to one aspect of the present disclosure, the co-precipitation reaction in step S2 is performed for 1 to 20 hours.

[0011] According to one aspect of the present disclosure, after step S3 is completed, the precursor has an average particle diameter D 50 .

[0012] According to one aspect of the present disclosure, the stirring speed in the batch reactor during step S1 is between 250 rpm and 1,000 rpm.

[0013] According to one aspect of the present disclosure, the transition metal compound solution is fed into the batch reactor at a flow rate of 5 mL / min to 40 mL / min during steps S2 and S3, and 2 mL / min to 30 mL / min during step S4.

[0014] According to one aspect of the present disclosure, the transition metal compound solution comprises at least one element selected from the group consisting of nickel, cobalt, and manganese.

[0015] According to one aspect of the present disclosure, the transition metal compound solution comprises: nickel in an amount of 60 mol% to 96 mol%; cobalt in an amount of 0 mol% to 20 mol%; and manganese in an amount of 4 mol% to 40 mol%.

[0016] According to one aspect of the present disclosure, the nitrogen-containing compound solution is delivered at a flow rate of 1.0 mL / min to 10.0 mL / min during steps S2 and S3, and 1.2 mL / min to 8.0 mL / min during step S4.

[0017] According to one aspect of the present disclosure, the basic compound solution is delivered at a flow rate of 3 mL / min to 35 mL / min during steps S2 and S3, and 2 mL / min to 30 mL / min during step S4.

[0018] According to one aspect of the present disclosure, the reaction solution in the batch reactor in step S1 has a pH of 10.5 to 13.5.

[0019] According to one aspect of the present disclosure, the reaction solution in the batch reactor in steps S2, S3, and S4 has a pH of 10.5 to 13.0.

[0020] According to one aspect of the present disclosure, the reaction solution in the batch reactor in steps S2, S3, and S4 has an ammonia concentration of 3,000 ppm to 7,000 ppm.

[0021] According to one aspect of the present disclosure, the reaction solution in the batch reactor in steps S2, S3, and S4 has a residual nickel concentration of 250 ppm or less.

[0022] According to one aspect of the present disclosure, the positive electrode active material precursor generated by steps S1 to S4 has a Span value of 0.38, as measured by the following Procedure 1:

[0023] [Equation 1]

[0024] Span = (Particle size D 90 - Particle size D 10 ) / Average particle size D 50

[0025] According to one aspect of the present disclosure, the method further comprises a step (S5) of washing and drying the positive electrode active material precursor generated by steps S1 to S4.

[0026] The present disclosure is designed to overflow the reaction solution through the overflow line when the batch reactor is filled with the reaction solution during the coprecipitation reaction of the precursor. Therefore, the ratio of the precursors within the reactor can be controlled, uniform growth of the precursors can be induced, and the problem of cracks on the surface of the precursor particles can be prevented. In addition, by using the overflow method, the amount of the reaction solution introduced and discharged can be controlled, allowing adjustment of the solid density within the reactor. Thus, even within the limited space of the reactor, precursor particles having a uniform particle size distribution and an average particle size D 50 in the range of 7 μm to 30 μm can be manufactured in a short amount of time.

[0027] In addition, in the present disclosure, when manufacturing large precursor particles having an average particle size D 50 of 7 μm to 30 μm, the stirring speed of the core growth steps (S2 to S4) of each precursor is controlled within a specific numerical range to prevent surface cracks that can occur due to collisions between particles. Therefore, during the roll-pressing process of manufacturing the positive electrode active material from the precursor, cracks on the surface of the active material particles can be prevented.

[0028] According to the precursor manufacturing method of the present disclosure, the formation of fine particles in the reaction solution is minimized during the core growth steps (S2 to S4). Therefore, a positive electrode active material precursor having a desired particle size and a uniform particle size distribution can be produced. In addition, there is no need for a separation process to remove fine particles, which significantly reduces the overall process time and cost. Therefore, the production line balance efficiency can be improved, thereby increasing the production amount of the positive electrode active material precursor. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a schematic diagram of a method for manufacturing a positive electrode active material precursor according to the present disclosure.

[0030] Figure 2 is an SEM image of a positive electrode active material precursor extracted and then dried after a coprecipitation reaction of 50 hours according to Example 1 of the present disclosure.

[0031] Figure 3The image shows a SEM image of a positive electrode active material precursor extracted and subsequently dried after a 50-hour co-precipitation reaction, according to Example 2 of this disclosure.

[0032] Figure 4 , Figure 5 , Figure 6 ,and Figure 7 The image shows a SEM image of the positive electrode active material precursor extracted after a 110-hour co-precipitation reaction, according to Comparative Example 1. Detailed Implementation

[0033] In the following description, specific details of the practice of this disclosure will be described in detail with reference to the accompanying drawings. However, in the following description, detailed descriptions of well-known functions or configurations will be omitted where it might make the subject matter of this disclosure unclear.

[0034] In the accompanying drawings, identical or corresponding components are given the same reference numerals. Furthermore, in the following description of specific embodiments, repeated descriptions of identical or corresponding elements may be omitted. However, even if the description of a component is omitted, it is not intended that such component is not included in any specific embodiment.

[0035] Before providing a detailed description of the specific embodiments disclosed herein, the terminology used herein will be briefly explained. The terminology used herein has been selected from commonly used terms in consideration of the functionality of this disclosure, and this may be changed based on the intention of a person skilled in the art, prior practice, or the introduction of new technologies. Furthermore, in certain cases, the terminology is arbitrarily chosen by the applicant, and the meaning of the term will be described in detail in the corresponding description of the specific embodiments. Therefore, the terminology of this disclosure should be based on the meaning of the term and the overall definition of this disclosure, rather than on the simple name definitions of each term.

[0036] As used herein, the singular forms “a / an” and “the” are intended to include the plural forms unless the context explicitly indicates a singular form. Furthermore, the plural forms are intended to include the singular forms unless the context explicitly indicates a plural form.

[0037] Furthermore, throughout the specification, when a portion is stated as "comprising (including)" a component, unless there is no specific conflict, it means that the portion may additionally contain (or include or have) another component, rather than excluding another component.

[0038] As used herein, the term “and / or” means all or only one of the elements that may exist in the group. For example, “A and / or B” should mean “only A, or only B, or both A and B”.

[0039] The advantages and features of the disclosed embodiments and implementations thereof will become apparent from the specific embodiments described hereinafter and the accompanying drawings. This disclosure is not limited to the disclosed embodiments but can be practiced with variation of them and in various embodiments and the disclosure of this disclosure is only complete and exhaustive when all the embodiments have been taken into consideration.

[0040] A method for manufacturing a positive electrode active material precursor using a batch reactor, the method comprising the steps of: (S1) forming a core of the precursor; (S2) growing the core formed in step S1; (S3) further growing the core grown in step S2; and (S4) further growing the core grown in step S3, wherein the stirring speed in the batch reactor is set to be 200 rpm to 900 rpm during step S2, 800 rpm or less during step S3, and 700 rpm or less during step S4, and the reaction solution is designed to overflow when the batch reactor is full of it.

[0041] Figure 1 is an explanatory diagram illustrating a method for manufacturing a positive electrode active material precursor according to the present disclosure. As shown in Figure 1 As shown in

[0042] According to the present disclosure, deionized water is added to the batch reactor, after which a solution containing a transition metal, a basic aqueous solution, and a solution containing an ammonium ion are introduced therein, and oxygen dissolved in the water is purged using an inert gas such as nitrogen and / or argon, thus creating a non-oxidative atmosphere within the reactor. This non-oxidative atmosphere can be maintained until the co-precipitation reaction is complete.

[0043] Next, the solution containing a transition metal, the basic aqueous solution, and the solution containing an ammonium ion can be continuously supplied into the batch reactor through an inlet provided by the batch reactor. These solutions are mixed within the reactor to form a reaction mixture, and through the co-precipitation reaction of this mixture, particles of the positive electrode active material precursor can be formed.

[0044] According to the present disclosure, before introducing the solution containing a transition metal, the basic aqueous solution, and the solution containing an ammonium ion into the batch reactor, the batch reactor is added with deionized water and purged with a non-reactive gas such as nitrogen and / or argon to remove oxygen dissolved in the water, thus creating an anti-oxidative atmosphere within the reactor. This anti-oxidative atmosphere can be maintained until the co-precipitation reaction is complete.

[0045] Next, a solution containing transition metals, an alkaline aqueous solution, and ammonium ions can be continuously supplied to the batch reactor through the inlet provided by the batch reactor. These solutions are mixed within the reactor to form a reaction solution, and the co-precipitation reaction of this reaction solution can lead to the formation of precursor particles of the positive electrode active material.

[0046] like Figure 1 As shown, an agitator can be installed in a batch reactor. The agitator can be an impeller, but is not limited to this. In this disclosure, when a three-bladed impeller is used as the agitator, the reaction slurry can be stirred from the bottom to the top.

[0047] Each step of the precursor manufacturing method according to this disclosure will be described in more detail below.

[0048] Nucleation steps (Step 1)

[0049] Step S1 involves the formation of nuclei for the anolyte precursor. Specifically, when a solution containing a transition metal, a nitrogen-containing compound, and an alkaline compound is introduced into a batch reactor and stirred, precursor particles in the form of transition metal hydroxides can be formed through co-precipitation. Here, the precursor particle nuclei have an average particle size D. 50 The range is from 1.2 μm to 6.0 μm, and more specifically from 1.5 μm to 5.5 μm.

[0050] In step S1, the stirring speed within the reactor can range from 250 rpm to 1,000 rpm, preferably from 350 rpm to 900 rpm, and more preferably from 450 rpm to 850 rpm. When the stirring speed in step S1 falls within these ranges, it can effectively induce uniform nucleation.

[0051] During step S1, the pH of the reaction solution can be between 10.5 and 13.5, preferably between 10.7 and 13.3, and more preferably between 10.8 and 13.0. When the pH of the reaction solution is within these ranges in step S1, controlled initial particle formation is permitted. The pH of the reaction solution can be adjusted by regulating the flow rate of the solution containing transition metals, nitrogen-containing compounds, and / or basic compounds.

[0052] The coprecipitation reaction in step S1 can be carried out in an inert atmosphere (such as nitrogen and / or argon) at a temperature of 40°C to 60°C. When the temperature is within this range, the rate of the coprecipitation reaction can be controlled.

[0053] The flow rate of the transition metal compound solution introduced into the batch reactor during step S1 can range from 2 mL / min to 35 mL / min, preferably from 3 mL / min to 30 mL / min, and more preferably from 4 mL / min to 25 mL / min. When the flow rate falls within these ranges, it allows control of the bulk density within the reactor, which is advantageous for the nucleation growth reaction.

[0054] The transition metal compound solution can include at least one element selected from the group consisting of nickel, cobalt, and manganese. For example, the transition metal compound solution can include a nickel-cobalt-manganese-based compound.

[0055] The transition metal compound solution in specific embodiments of the present disclosure can include the following: nickel in an amount of 60 mol% to 96 mol% and preferably 80 mol% to 96 mol%; cobalt in an amount of 0 mol% to 20 mol% and preferably 0 mol% to 10 mol%; and manganese in an amount of 4 mol% and 40 mol% and preferably 4 mol% to 20 mol%. When the nickel, cobalt, and manganese contents in the solution fall within these ranges, it is thereby possible to manufacture a battery having an increased energy density.

[0056] The transition metal compound solution can be prepared by dissolving a transition metal-containing raw material in a solvent such as water. The concentration of the transition metal compound solution can range from 1.80 M to 2.65 M and preferably from 2.00 M to 2.55 M from the viewpoint of productivity. The amount of addition of each transition metal-containing raw material can be determined in consideration of the desired molar ratio of transition metals in the final cathode active material.

[0057] The transition metal-containing raw material can include an acetate, carbonate, nitrate, sulfate, halide, sulfide, oxide, hydrate, hydroxide, and / or oxyhydroxide of the transition metal, but is not limited thereto. Preferably, the raw material can include a transition metal hydrate, which is advantageous in terms of facilitating storage and use.

[0058] The transition metal compound solution can be prepared by dissolving raw materials containing nickel, cobalt, and manganese in water. For example, the nickel-containing raw material can be Ni(OH)2, NiO, NiOOH, NiCO3.2Ni(OH)2.4H2O, NiC2O2.2H2O, Ni(NO3)2.6H2O, NiSO4, NiSO4.6H2O, a nickel salt of a fatty acid, a nickel halide, or a combination thereof. The cobalt-containing raw material can be CoSO4, Co(OH)2, CoOOH, Co(OCOCH3)2.4H2O, Co(NO3)2.6H2O, CoSO4.7H2O, Co(SO4)2.7H2O, or a combination thereof. The manganese-containing raw material can be manganese oxide (such as Mn2O3, MnO2, and Mn3O4), a manganese salt (such as MnCO3, Mn(NO3)2, MnSO4, MnSO4.H2O, a manganese acetate, a manganese dicarboxylate, a manganese citrate, and a manganese salt of a fatty acid), a manganese oxyhydroxide, a manganese chloride, or a combination thereof. For example, NiSO4.6H2O can be used as the nickel source, CoSO4.7H2O can be used as the cobalt source, and MnSO4.H2O can be used as the manganese source.

[0059] If the anode active material precursor includes other metal elements (M) in addition to nickel (Ni), manganese (Mn), and cobalt (Co), raw materials containing such additional metal elements (M) can be added as needed during preparation of the transition metal compound solution. Such metal elements (M) can include one or more elements selected from the group consisting of W, Y, Ba, Ca, Mo, Cr, Al, Zr, Ti, Mg, Ta, and Nb. In addition, the raw materials containing the metal elements (M) can include acetates, carbonates, nitrates, sulfates, halides, sulfides, hydroxides, oxyhydroxides, and / or oxides of such metal elements (M), but are not limited thereto.

[0060] During step S1, the flow rate of the nitrogen-containing compound solution introduced into the batch reactor can range from 1.0 mL / min to 10 mL / min, preferably from 1.2 mL / min to 8.0 mL / min, and more preferably from 1.5 mL / min to 5.0 mL / min. When the flow rate falls within these ranges, an appropriate ammonia concentration in the reaction solution can be maintained while controlling nucleation.

[0061] The nitrogen-containing compound solution can act as a complexing agent to assist in the coprecipitation reactions among various transition metals within the transition metal compound solution.

[0062] The nitrogen-containing compound solution can include an ammonium cation complexing agent. The complexing agent can be at least one compound selected from the group consisting of NH4OH, (NH4)2SO4, NH4NO3, NH4Cl, CH3COONH4, and NH4CO3. For example, the nitrogen-containing compound solution can be prepared by dissolving the ammonium cation complexing agent in a solvent. The solvent used can be water or a mixture of water and an organic solvent such as an alcohol. The concentration of the nitrogen-containing compound solution can range from 1 wt% to 50 wt% and preferably from 5 wt% to 25 wt%. In this regard, the ammonia concentration in the reactor can be suitably controlled.

[0063] During step S1, the flow rate of the basic compound solution introduced into the batch reactor can range from 2.0 mL / min to 30.0 mL / min, preferably from 2.5 mL / min to 25.0 mL / min, and more preferably from 2.8 mL / min to 20.0 mL / min. When the flow rate falls within these ranges, it is possible to maintain a suitable pH level in the reaction solution while inducing uniform nucleation.

[0064] The basic aqueous solution can include at least one selected from the group consisting of hydrates and hydroxides of alkali metals, and hydrates and hydroxides of alkaline earth metals. For example, the basic aqueous solution can be prepared by dissolving at least one selected from the group consisting of NaOH, KOH, and Ca(OH)2 in a solvent. The concentration of the basic aqueous solution can range from 5 wt% to 50 wt% and preferably from 10 wt% to 45 wt%. In this case, it is easy to maintain a suitable pH value in the reaction solution.

[0065] In step S1, the co-precipitation reaction can be performed for 0.5 hours or more, preferably from 0.5 hours to 10 hours, and more preferably from 0.5 hours to 8 hours. Thus, step S1 can be ended once the specified co-precipitation reaction time has elapsed. When the co-precipitation reaction time during step S1 falls within these ranges, it is ensured that precursor nuclei of uniform composition are sufficiently formed, thereby enhancing the yield of the positive active material precursor.

[0066] Nucleus growth steps (steps S2 to S4)

[0067] Steps S2 to S4 are growth periods of the nuclei produced in step S1. Specifically, in step S2, the nuclei produced in step S1 are grown. Step S3 is to further grow the nuclei grown in step S2, and in step S4, the nuclei grown in step S3 are allowed to further grow.

[0068] In steps S2 to S4, based on Ostwald ripening, relatively small particles among the particles generated in step 1 disappear and the average particle diameter of relatively large particles increases. The average particle diameter D of the precursor particles 50 The growth can be 0.5 μm to 1.5 μm every 5 hours at the beginning of steps S2 to S4, and then 0.1 μm to 0.3 μm every 5 hours in the latter part of steps S2 to S4. As steps S2 to S4 proceed, the particle size distribution of the precursor in the reaction solution becomes more uniform, with a gradual decrease in the span value of the precursor particles.

[0069] In steps S2 to S4, the pH of the reaction solution can range from 10.5 to 13.0, preferably from 10.8 to 12.5, and more preferably from 11.0 to 12.2. When the pH of the reaction solution is within this range in steps S2 to S4, the nucleus growth reaction predominates over the nucleus generation reaction. The pH of the reaction solution can be adjusted by adjusting the flow rates of the transition metal compound solution, the nitrogen-containing compound solution, the basic compound solution, and / or the acidic compound solution. The pH of the reaction solution can be adjusted by adjusting the flow rates of the solutions containing the transition metal, the nitrogen-containing compound, the basic compound, and / or the acidic compound.

[0070] The concentration of ammonia in the reaction solution during steps S2 to S4 can range from 3,000 ppm to 7,000 ppm, preferably from 3,200 ppm to 6,500 ppm, and more preferably from 3,400 ppm to 6,000 ppm. If the ammonia concentration is less than 3,000 ppm, the formation of transition metal hydrates is preferred over the coprecipitation reaction, causing a problem of new fine particles being generated in the reaction solution. If the ammonia concentration exceeds 7,000 ppm, the residual nickel in the reaction solution forms a new complex with ammonia, causing new fine particles to be generated in the reaction solution. The concentration of ammonia in the reaction solution can be adjusted by the flow rate of the nitrogen-containing compound reaction delivery.

[0071] During steps S2 to S4, if the ammonia concentration in the reaction solution is maintained between 3,000 ppm and 7,000 ppm, the concentration of residual nickel in the solution can tend to increase with the progress of the coprecipitation reaction. In steps S2 to S4, the concentration of residual nickel in the reaction solution in the batch reactor can be 250 ppm or less, preferably between 0 ppm and 225 ppm, and more preferably between 0 ppm and 200 ppm. Here, the concentration of residual nickel refers to the concentration of unreacted nickel remaining in the solution during the conversion of the transition metal compound solution into the positive electrode active material precursor. When the concentration of residual nickel in the reaction solution is within these ranges, according to Le Chatelier's principle, the formation of new fine particles can be suppressed in the reaction solution. The concentration of residual nickel in the reaction solution can be controlled by the flow rate of the transition metal compound solution.

[0072] The coprecipitation reaction in steps S2 to S4 can be performed under a non-reactive gas atmosphere, such as nitrogen or argon, at a temperature of 40°C to 60°C. Maintaining the temperature within this range allows for a controlled reaction rate.

[0073] As the coprecipitation reaction in steps S2 to S4 progresses, when the batch reactor is filled with the reaction solution, the reaction solution overflows through a drain line. Therefore, the bulk density in the reactor is controlled to prevent the problem of cracks forming on the particle surfaces. In addition, the overflow method can adjust the amount of reaction solution in and out, allowing the bulk density in the reactor to be controlled. Thus, even in the limited space of the reactor, large precursor particles having a uniform particle size distribution and an average particle diameter D 50 Large precursor particles in the range of 7 μm to 30 μm.

[0074] The sub-steps of the core growth step are described in detail below.

[0075] (1) Step S2

[0076] Once the average particle diameter D 50 Step S2 can be initiated once the average particle diameter D

[0077] During step S2, the stirring speed within the reactor can be between 200 rpm and 900 rpm, preferably between 225 rpm and 850 rpm, and more preferably between 250 rpm and 800 rpm. If the stirring speed in step S2 exceeds 900 rpm, the side reactions can overpower the core growth reaction, resulting in the production of a large amount of fine particles and causing the particle size distribution of the precursor to be uneven. If the stirring speed is lower than 200 rpm, the aspect ratio of the produced precursor becomes low, reducing the proportion of the precursor within the battery per unit volume, and consequently the battery capacity.

[0078] During step S2, the flow rate of the transition metal compound solution introduced into the batch reactor can range from 5 mL / min to 40 mL / min, preferably from 7 mL / min to 35 mL / min, and more preferably from 10 mL / min to 30 mL / min. When the flow rate falls within these ranges, the growth rate of the formed core can be suitably controlled.

[0079] During step S2, the flow rate of the nitrogen-containing compound solution can be set to be the same as in step S1. For example, during step S2, the flow rate of the nitrogen-containing compound solution can range from 1.0 mL / min to 10.0 mL / min, preferably from 1.2 mL / min to 8.0 mL / min, and more preferably from 1.5 mL / min to 5.0 mL / min.

[0080] During step S2, the flow rate of the basic compound solution can be set to be between 3 mL / min and 35 mL / min, preferably between 5 mL / min and 30 mL / min, and more preferably between 8 mL / min and 25 mL / min. A flow rate falling within these ranges allows the pH of the reaction solution to be maintained within a suitable range.

[0081] The co-precipitation reaction in step S2 can be performed for at least 1 hour, preferably for 1.5 hours to 20 hours, and more preferably for 2 hours to 15 hours. Once the co-precipitation reaction time has elapsed, step S2 can be ended. If the co-precipitation reaction time during step S2 falls within this range, the aspect ratio of the precursor increases, thus increasing the energy density of the battery and regulating the formation of fine particles.

[0082] (2) Step S3

[0083] Once step S2 is completed, step S3 can be initiated. The distinguishing feature of step S3 compared to step S2 is the difference in stirring speed.

[0084] The agitation speed within the reactor during the phase of step S3 can be slower than in step S2. In particular, the agitation speed during step S3 can be at most 800 rpm, preferably between 175 rpm and 750 rpm, and more preferably between 200 rpm and 700 rpm. If the agitation speed in step S3 exceeds 800 rpm, the span value increases.

[0085] The flow rate of the solution of transition metal compound introduced into the batch reactor in step S3 can be the same as in step S2. For example, the flow rate during step S3 can range from 5 mL / min to 40 mL / min, preferably from 7 mL / min to 35 mL / min, and more preferably from 10 mL / min to 30 mL / min.

[0086] The flow rate of the solution of nitrogen-containing compound in step S3 can be the same as in step S2. For example, the flow rate during step S3 can range from 1.0 mL / min to 10.0 mL / min, preferably from 1.2 mL / min to 8.0 mL / min, and more preferably from 1.5 mL / min to 5.0 mL / min.

[0087] The flow rate of the solution of basic compound in step S3 can be the same as in step S2. For example, the flow rate during step S3 can range from 3 mL / min to 35 mL / min, preferably from 5 mL / min to 30 mL / min, and more preferably from 8 mL / min to 25 mL / min.

[0088] The co-precipitation reaction in step S3 can be performed for at least 5 hours, preferably between 7 hours and 35 hours. If the co-precipitation reaction time in step S3 falls within these ranges, the average particle size D 50 of the precursor particles can be between 6.5 pm and 13.0 pm. However, if the average particle size D 50 of the precursor particles does not reach between 6.5 pm and 13.0 pm, the co-precipitation reaction of step S3 can be continued under the same conditions until this average particle size is reached.

[0089] After completion of step S3, the average particle size D 50 of the precursor particles can be between 6.5 pm and 13.0 pm, preferably between 7.5 pm and 12.5 pm, and more preferably between 8.0 pm and 12.0 pm. If, after step S3, the average particle size D 50 of the precursor particles is less than 6.5 pm, the co-precipitation reaction of step S3 can be continued under the same conditions until this average particle size is reached. 50 The precursor particles targeted for manufacture can be challenging. If, after step S3, the average particle size D 50over 13.0 pm, the co-precipitation reaction continued by stirring can increase the frequency of particle collision, potentially causing cracks on the particle surface. Therefore, in the present disclosure, once the average particle size D 50 between 6.5 pm and 13.0 pm, step S3 can be ended and step S4 can be started.

[0090] (3) Step S4

[0091] Once the average particle size D 50 between 6.5 pm and 13.0 pm, step S3 can be ended and step S4 can be started. Compared to step S3, step S4 is characterized by changing the flow rates of the transition metal compound solution, the nitrogen-containing compound solution, and the basic compound solution in the batch reactor and the stirring speed.

[0092] The stirring speed in the reactor during step S4 can be slower than in steps S2 and S3. Specifically, during step S4, the stirring speed can be at most 700 rpm, preferably between 150 rpm and 650 rpm, and more preferably between 175 rpm and 600 rpm. If the stirring speed during step S4 exceeds 700 rpm, as the co-precipitation reaction time increases, precursor particles having a large average particle size D 50 cracks on the particle surface.

[0093] During step S4, the flow rate of the transition metal compound solution introduced into the batch reactor can range from 2 mL / min to 30 mL / min, preferably from 3 mL / min to 25 mL / min, and more preferably from 5 mL / min to 20 mL / min. A flow rate conforming to these ranges allows precursor particles having an average particle size D 50 between 6.5 pm and 13.0 pm to grow further, while inhibiting the formation of new fine particles. Since the overflow method is applied during precursor manufacturing, even if the flow rate of the transition metal compound solution in step S4 is reduced compared to steps S2 and S3, the present disclosure can prevent the growth rate of the precursor particles from decreasing.

[0094] Taking into account the flow rate of the transition metal compound solution during step S4, the flow rate of the nitrogen-containing compound solution during step S4 can range from 1.0 mL / min to 10.0 mL / min, preferably from 1.2 mL / min to 8.0 mL / min, and more preferably from 1.5 mL / min to 5.0 mL / min.

[0095] Likewise, considering the flow rate of the transition metal compound solution during step S4, the flow rate of the basic compound solution during step S4 can range from 2 mL / min to 30 mL / min, preferably from 3 mL / min to 25 mL / min, and more preferably from 4 mL / min to 20 mL / min.

[0096] For the anode active material precursor produced by steps S1 to S4, the span value (as defined by the following Equation 1) can be 0.38 or less, more preferably 0.35 or less, and more preferably between 0.25 and 0.33:

[0097] [Equation 1]

[0098] Span = (Particle size D 90 - Particle size D 10 ) / Average particle size D 50

[0099] When the span value of the precursor is within these ranges, it indicates that the deviation of the particle size diameter is small, which helps to achieve the desired tap density, specific surface area, and other physical properties of the precursor, and can also improve the charge / discharge capacity of the anode material.

[0100] Further, after steps S1 to S4, the method of manufacturing the precursor according to the present disclosure can further include a washing and drying step (step S5).

[0101] Washing and drying step (step S5)

[0102] Step S5 includes washing and drying the anode active material precursor generated by steps S1 to S4. This step is adapted to separate the anode active material precursor from the reaction mixture and then collect it.

[0103] Once the average particle size D 50 of the precursor grown in step S4 reaches between 7 μm and 30 μm, specifically between 8 μm and 27 μm, and more specifically between 9 μm and 25 μm, the washing process can be started. For this purpose, the reaction solution containing the precursor can be transferred to a device for a filter press process. The filter press process includes inputting the reaction mixture under pressure into a sealed filtration chamber, in which the solid (filter cake) and liquid (filtrate) are separated by a filter medium, while the washing process is performed. Once the washing of the separated precursor particles is completed, the precursor particles are purged with nitrogen to prevent oxidation of the positive active material precursor.

[0104] After the washing process of the precursor is completed, the next step is to dry the precursor to remove the moisture of the anode active material precursor. The drying process is designed to reduce the moisture content to 1.0 wt% or less, and preferably to 0.8 wt% or less, based on the total weight of the precursor. At this moisture content level, good productivity and quality can be brought in the subsequent manufacturing process.

[0105] Further, the method of manufacturing the precursor according to the present disclosure can further include a milling process and / or a sorting process as needed.

[0106] Hereinafter, specific embodiments of the present disclosure will be described in detail so that those having ordinary knowledge in the art can easily implement the present disclosure. However, the present disclosure can be implemented in various different forms, and is not limited to the specific embodiments described herein.

[0107] Examples and Comparative Examples

[0108] Example 1

[0109] (1) Nucleation step (step S1)

[0110] Hydrates of NiSO4·6H2O, CoSO4·7H2O, and MnSO4·H2O were mixed in a molar ratio of nickel : cobalt : manganese of 91 : 4.5 : 4.5 in deionized water to prepare a 2.4 M transition metal compound solution.

[0111] In a 30 liter batch reactor, 15 liters of deionized water was introduced, followed by purging with nitrogen gas at a flow rate of 5 mL / min to remove dissolved oxygen in the water and create a non-oxidizing atmosphere inside the reactor. Subsequently, while continuing to purge the reactor with nitrogen gas at a flow rate of 5 mL / min, the transition metal compound solution was delivered at a flow rate of 4.51 mL / min, the 25 wt% NaOH solution was delivered at a flow rate of 2.84 mL / min, and the 9 wt% NH4OH solution was delivered at a flow rate of 3.00 mL / min.

[0112] During this step, adjustments were made to maintain the temperature of the batch reactor at 50°C, the pH of the reaction mixture at 11.8, and the stirring speed of the impeller at 750 rpm.

[0113] The co-precipitation reaction in the nucleation step (S1) was carried out for 0.5 hours to an average particle size D 50 to 1.2 μm to 6.0 μm.

[0114] (2) Nucleus growth step (steps S2 to S4)

[0115] After completion of step S1, 1 N sulfuric acid solution was introduced into the batch reactor to adjust the pH of the reaction solution to 11.2.

[0116] After completion of step S1, the flow rates of the components were changed to perform step S2. Specifically, the 2.4 M transition metal compound solution was introduced at a flow rate of 18.03 mL / min, the 25 wt% NaOH solution was introduced at a flow rate of 11.33 mL / min, and the 9 wt% NH4OH solution was introduced at a flow rate of 3.00 mL / min. The impeller stirring speed in step S2 was changed to 400 rpm. The co-precipitation reaction in step S2 was continued for 4.5 hours.

[0117] After step S2, the components of step S3 were started at the same flow rates as in step S2, but the impeller stirring speed was changed to 300 rpm. The co-precipitation reaction in step S3 was continued for 15 hours. If the average particle diameter D 50 If the average particle diameter D

[0118] After completion of step S3, the flow rates of the components of step S4 were changed again. Specifically, the 2.4 M transition metal compound solution was introduced at a flow rate of 9.02 mL / min, the 25 wt% NaOH solution was introduced at a flow rate of 5.67 mL / min, and the 9 wt% NH4OH solution was introduced at a flow rate of 2.10 mL / min. The impeller stirring speed in step S4 was changed to 200 rpm. The co-precipitation reaction in step S4 was continued for 30 hours.

[0119] During steps S2 to S4, if the batch reactor was filled with the reaction solution, the reaction solution was overflowed through the drain line.

[0120] As steps S2 to S4 were performed, 100 mL of the reaction solution was extracted every 5 hours, after which ammonia titration was performed. To maintain the ammonia concentration in the reactor at 4,000 ppm, when the ammonia concentration decreased, further addition of the NH4OH solution was performed.

[0121] During steps S2 to S4, 50 mL of the reaction solution was extracted every hour, and was tested at room temperature (25°C) to ensure that the pH was maintained at 11.2. Once the pH measurement of the extracted reaction solution was completed, the reaction solution was reintroduced into the reactor.

[0122] (3) Washing and drying step (step S5)

[0123] After the co-precipitation reaction in steps S1 to S4 is performed for a total of 50 hours, the reaction solution is transferred to a pressure filtration process. In the pressure filtration process, the reaction solution is pressed into a sealed filtration chamber in which the solid (filter cake) and liquid (filtrate) are separated by a filtration medium while performing a washing process. After the washing of the precursor particles is completed, nitrogen, argon, oxygen, or pressurized air is supplied at a pressure of 0.4 MPa to dehydrate the supernatant and wash the liquid.

[0124] After the pressure filtration and washing processes, the positive electrode active material precursor is dried at a temperature of 150°C for 8 hours to reduce the moisture content in the positive electrode active material precursor to 0.5 wt% or less.

[0125] Example 2

[0126] The positive electrode active material precursor is manufactured in the same manner as in step S1, except that the impeller stirring speed in step S1 is adjusted to 650 rpm.

[0127] Comparative Example 1

[0128] The positive electrode active material precursor is manufactured in the same manner as in step S1, except that when the batch reactor is filled with the reaction solution in steps S2 to S4, the introduction of the components and the rotation of the impeller are stopped, and the mixture is left to stand for one hour to allow the components to settle, after which 10 L to 12 L of the amount of supernatant is discharged to separate the NCM precursor and the supernatant.

[0129] In step S1, the co-precipitation reaction time is continuously performed for 0.5 hours to an average particle diameter D 50 to between 6.5 pm and 13.0 pm.

[0130] The co-precipitation reaction in step S2 is continued for 4.5 hours.

[0131] In step S3, the co-precipitation reaction time is continuously performed for 15 hours to an average particle diameter D 50 to between 6.5 pm and 13.0 pm.

[0132] In step S4, the co-precipitation reaction time is continuously performed for 90 hours to an average particle diameter D 50 to between 7.0 pm and 30.0 pm.

[0133] Experimental Example 1: SEM image analysis of the precursor

[0134] During steps S2 to S4 in Examples 1 to 2 and Comparative Example 1, 50 ml of the reaction solution is extracted and dried every 5 hours, and then SEM (scanning electron microscope) imaging is performed on the precursor particles.

[0135] Figure 2 SEM image of a positive electrode active material precursor extracted after 50 hours of co-precipitation reaction and subsequently dried according to the embodiment 1 of the present disclosure.

[0136] Figure 3 SEM image of a positive electrode active material precursor extracted after 50 hours of co-precipitation reaction and subsequently dried according to the embodiment 2 of the present disclosure.

[0137] Figure 4 Figure 5 Figure 6 Figure 7 SEM image of a positive electrode active material precursor extracted after 110 hours of co-precipitation reaction and subsequently dried according to the comparative example 1 of the present disclosure.

[0138] As shown in Table 1, the number of particles in the SEM images observed in the embodiments 1 and 2 (stirring speed between 200 rpm and 900 rpm during step S2, stirring speed of 800 rpm or lower during step S3, and stirring speed of 700 rpm or lower during step S4, and performing overflow when the reactor is full) was significantly less compared to the comparative example 1 in which the sediment separation was performed when the reactor was full of reaction solution. It was also confirmed that surface cracks did not appear on the precursor particles. Figures 2 to 7

[0139] Experimental Example 2: Analysis of particle size and composition of the precursor

[0140] During steps S2 to S4 in the embodiments 1 to 2 and the comparative examples 1 to 2, 50 ml of reaction solution was extracted every 5 hours, followed by analysis of the particle size and composition of the precursor.

[0141] Specifically, the particle size was analyzed under wet conditions using Mastersizer 2000 of Malvern.

[0142] The composition analysis was performed under inductively coupled plasma conditions using Agilent 5900 ICP-OES.

[0143] The results of the analysis of the particle size and composition of the reaction solution extracted from the embodiments 1 to 2 and the comparative examples 1 to 2 are summarized in Table 1 below.

[0144] Table 1

[0145]

[0146] ​​​​According to Table 1, lower span values and shorter co-precipitation reaction times were observed in Examples 1 and 2 (stirring speed between 200 rpm and 900 rpm during step S2, stirring speed of 800 rpm or less during step S3, and stirring speed of 700 rpm or less during step S4, and overflow performed when the reactor was full) compared to Comparative Example 1 in which the sediment separation was performed when the reactor was full. This indicates that the particle size distribution of the precursors manufactured in Examples 1 and 2 is more uniform than that of the precursors in Comparative Example 1, and the co-precipitation reaction time required to manufacture the precursors in Examples 1 and 2 is significantly reduced compared to Comparative Example 1.

[0147] Thus far, the technical concept of the present disclosure has been described with reference to some specific embodiments and examples shown in the accompanying drawings. However, it should be understood that various substitutions, modifications, and changes can be made without departing from the scope of the technical concept and the present disclosure that can be understood by those skilled in the art to which the present disclosure belongs. Furthermore, it should be understood that such substitutions, modifications, and changes all fall within the scope of the appended claims.

Claims

1. A method of manufacturing a positive active material precursor using a batch reactor, the method comprising the steps of: (S1) forming a core of the precursor; (S2) growing the core formed in step S1 ; (S3) further growing the core grown in step S2; and (S4) further growing the core grown in step S3, wherein a stirring speed in the batch reactor is set to: 200 rpm to 900 rpm during step S2, 800 rpm or less during step S3, and 700 rpm or less during step S4, and a reaction solution is designed to overflow when the batch reactor is filled with it.

2. The method of claim 1, wherein a co-precipitation reaction in step S2 is conducted for 1 to 20 hours.

3. The method of claim 1, wherein after completion of step S3, the precursor has an average particle size D of 6.5 μm to 13.0 μm 50 .

4. The method of claim 1, wherein a stirring speed in the batch reactor during step S1 is between 250 rpm and 1,000 rpm.

5. The method of claim 1, wherein a transition metal compound solution is fed into the batch reactor at a flow rate of: 5 mL / min to 40 mL / min during steps S2 and S3, and 2 mL / min to 30 mL / min during step S4.

6. The method of claim 5, wherein the transition metal compound solution comprises at least one element selected from the group consisting of nickel, cobalt, and manganese.

7. The method of claim 5, wherein the transition metal compound solution comprises: nickel in an amount of 60 mol% to 96 mol%; cobalt in an amount of 0 mol% to 20 mol%; and manganese in an amount of 4 mol% to 40 mol%.

8. The method of claim 1, wherein a nitrogen-containing compound solution is delivered at a flow rate of: 1.0 mL / min to 10.0 mL / min during steps S2 and S3, and 1.2 mL / min to 8.0 mL / min during step S4.

9. The method of claim 1, wherein a basic compound solution is delivered at a flow rate of: 3 mL / min to 35 mL / min during steps S2 and S3, and 2 mL / min to 30 mL / min during step S4.

10. The method of claim 1, wherein the reaction solution in the batch reactor in step S1 has a pH of 10.5 to 13.

5.

11. The method of claim 1, wherein the reaction solution in the batch reactor in steps S2, S3, and S4 has a pH of 10.5 to 13.

0.

12. The method of claim 1, wherein the reaction solution in the batch reactor in steps S2, S3, and S4 has an ammonia concentration of 3,000 ppm to 7,000 ppm.

13. The method according to claim 1, wherein the reaction solution in the batch reactor in steps S2, S3, and S4 has a residual nickel concentration of 250 ppm or less.

14. The method according to claim 1, wherein the positive electrode active material precursor produced by steps S1 to S4 has a Span value of 0.38, as measured by the following Procedure 1: [Equation 1] Span = (Particle size D 90 - Particle size D 10 ) / Average particle size D 50 .

15. The method according to claim 1, further comprising a step (S5) of washing and drying the positive electrode active material precursor produced by steps S1 to S4.

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