Manufacturing method for positive electrode active material precursor

Abstract

A manufacturing method for a positive electrode active material precursor according to the present invention comprises: a first step of producing nuclei of the precursor; and a second step of growing the nuclei produced in the first step, wherein, in the first and second steps, the flow rate with which a transition metal compound solution is added into a batch-type reactor is 15-55mLA / min, and the agitation speed in the reactor is 200-875rpm in the first step and 475rpm or lower in the second step.

Description

Method for manufacturing a cathode active material precursor

[0001] The present invention relates to a method for producing a positive electrode active material precursor, and more particularly, to a method for producing a positive electrode active material precursor using a batch reactor.

[0002] The recent expansion of the battery electric vehicle (BEV) market has led to an increase in demand for secondary batteries. Secondary batteries typically include a cathode, anode, electrolyte, and a separator. The cathode and anode include active materials capable of intercalating and deintercalating lithium ions, for example.

[0003] Representative methods for manufacturing positive electrode active material precursors include a continuous stirred-tank reactor (CSTR) method for manufacturing positive electrode active material precursors and a batch reactor method for manufacturing positive electrode active material precursors. The manufacturing method using a continuous reactor is a method in which raw materials are introduced, co-precipitated, and simultaneously the precursor formed into particles is discharged. The manufacturing method using a batch reactor is a method in which raw materials are introduced according to the reactor volume for a certain period of time, reacted, and the precursor is discharged after the reaction is complete.

[0004] In a batch reactor, precursor particles are formed over the course of the co-precipitation reaction. To form precursor particles larger than a certain size, the precursor particles formed through the initial nucleation reaction must continuously grow.

[0005] However, during the growth reaction of the precursor particles, new nucleation reactions continuously occur, continuously producing small precursor particles. Consequently, the average particle diameter of the precursor particles decreases and the particle size distribution becomes uneven at the end of the co-precipitation reaction, which poses a problem. In this case, the physical properties of the cathode active material precursor to be manufactured, such as tap density and specific surface area, do not meet the target values, and the charge / discharge capacity performance of the battery is also adversely affected.

[0006] To address this, conventional techniques have employed ACM (Air Classifier Mill), Air Jet Mill, etc. to control the influence of the precursor fine particles mentioned above, by capturing the fine particles through a separate bag filter during the grinding process, or by transferring the reaction solution containing the precursor from the reactor to a cyclone facility and centrifuging to remove the fine particles. However, these conventional techniques have the problem of deteriorating the line of balance (LOB) efficiency and reducing the production volume of the positive electrode active material precursor due to increased costs and overall process time due to additional processes / equipment.

[0007] The present invention is intended to solve the above problem, and its purpose is to provide a method for manufacturing a precursor having a uniform particle size distribution by minimizing the formation of precursor fine particles during the precursor nucleus growth step by controlling the co-precipitation reaction conditions without an additional process.

[0008] A method for producing a positive electrode active material precursor according to one aspect of the present invention comprises a first step of generating a nucleus of the precursor, and a second step of growing the nucleus generated by the first step, wherein in the first step and the second step, a flow rate of a transition metal compound solution introduced into a batch reactor is 15 mL / min to 55 mL / min, a stirring speed in the reactor in the first step is 200 rpm to 875 rpm, and a stirring speed in the reactor in the second step is 475 rpm or less.

[0009] According to one aspect of the present invention, the transition metal compound solution may include at least one element selected from the group consisting of nickel, cobalt, and manganese.

[0010] According to one aspect of the present invention, the transition metal compound solution may contain 60 mol% to 96 mol% of nickel, 0 mol% to 20 mol% of cobalt, and 4 mol% to 40 mol% of manganese.

[0011] According to one aspect of the present invention, the reaction solution inside the batch reactor in the first step may have a pH of 10.5 to 13.5.

[0012] According to one aspect of the present invention, the reaction solution inside the batch reactor in the second step may have a pH of 10.5 to 13.5.

[0013] According to one aspect of the present invention, in the second step, the reaction liquid inside the batch reactor may have an ammonia concentration of 3,000 ppm to 7,000 ppm.

[0014] According to one aspect of the present invention, the input flow rate of the nitrogen-containing compound solution in the first step and the second step may be 1.0 mL / min to 10.0 mL / min.

[0015] According to one aspect of the present invention, the input flow rate of the basic compound solution in the first step and the second step may be 8.0 mL / min to 32.0 mL / min.

[0016] According to one aspect of the present invention, the positive electrode active material precursor produced through the first step and the second step may have a span value of 0.55 or less according to the following equation 1.

[0017] [Formula 1]

[0018] Span = (particle diameter D) 90 - Particle diameter D 10 ) / average particle diameter D 50

[0019] According to one aspect of the present invention, a third step of washing and drying the positive electrode active material precursor produced through the first step and the second step may be further included.

[0020] According to the present invention, by controlling the input flow rates of each component into the reactor during the co-precipitation reaction and the stirring speed during the precursor nucleation and growth stages to a constant level, the co-precipitation reaction time required for precursor production can be shortened while minimizing the formation of fine particles in the reaction solution during the nucleus growth stage. As a result, a positive electrode active material precursor having a targeted particle size and uniform particle size distribution can be produced within a short period of time.

[0021] In addition, the present invention minimizes the formation of fine particles during precursor nucleus growth, so that a separate process for removing fine particles is not required, and thus the overall process time can be significantly reduced and process costs can be reduced, and accordingly, line formation efficiency can be improved, thereby increasing the production volume of positive electrode active material precursors.

[0022] Figure 1 is an exemplary diagram of a method for manufacturing a positive electrode active material precursor according to the present invention.

[0023] Figure 2 is an SEM image taken after drying the extracted positive electrode active material precursor after performing a co-precipitation reaction for 48 hours according to Example 1 of the present invention.

[0024] Figure 3 is an SEM image taken after drying the extracted positive electrode active material precursor after performing a co-precipitation reaction for 34 hours according to Example 2 of the present invention.

[0025] Figure 4 is an SEM image taken after drying the extracted positive electrode active material precursor after performing a co-precipitation reaction for 55 hours according to Comparative Example 1 of the present invention.

[0026] Figure 5 is an SEM image taken after drying the extracted positive electrode active material precursor after performing a co-precipitation reaction for 55 hours according to Comparative Example 2 of the present invention.

[0027] Hereinafter, specific details for implementing the present disclosure will be described in detail with reference to the attached drawings. However, in the following description, specific descriptions of widely known functions or configurations will be omitted if they may unnecessarily obscure the gist of the present disclosure.

[0028] In the attached drawings, identical or corresponding components are assigned the same reference numerals. Furthermore, in the description of the embodiments below, duplicate descriptions of identical or corresponding components may be omitted. However, even if a description of a component is omitted, it is not intended that such component is not included in any embodiment.

[0029] The terms used in this disclosure will be briefly described, followed by a detailed description of the disclosed embodiments. The terms used in this specification have been selected from widely used, current terms, taking into account the functions of the present disclosure. However, these terms may vary depending on the intentions of engineers working in the relevant fields, precedents, the emergence of new technologies, etc. Furthermore, in certain cases, terms may be arbitrarily selected by the applicant, and in such cases, their meanings will be described in detail in the relevant description of the invention. Therefore, the terms used in this disclosure should not be defined simply as names of terms, but rather based on their meanings and the overall content of the present disclosure.

[0030] In this disclosure, singular expressions include plural expressions unless the context clearly specifies that they are singular. Furthermore, plural expressions include singular expressions unless the context clearly specifies that they are plural.

[0031] In this disclosure, when it is said that a part includes a certain component, this does not mean that other components are excluded, but rather that other components may be included, unless specifically stated otherwise.

[0032] In this disclosure, the description of “A and / or B” means A, or B, or A and B.

[0033] The advantages and features of the disclosed embodiments, and methods for achieving them, will become clearer with reference to the embodiments described below, along with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided solely to ensure the completeness of the disclosure and to fully inform those skilled in the art of the scope of the invention.

[0034] A method for manufacturing a positive electrode active material precursor according to the present invention comprises a first step of generating a nucleus of a precursor, and a second step of growing the nucleus generated by the first step, wherein a flow rate of a transition metal compound solution introduced into a batch reactor in the first and second steps is 15 mL / min to 55 mL / min, a stirring speed in the reactor in the first step is 200 rpm to 875 rpm, and a stirring speed in the reactor in the second step is 475 rpm or less.

[0035] FIG. 1 is an exemplary diagram of a method for manufacturing a positive electrode active material precursor according to the present invention. As illustrated in FIG. 1, a transition metal-containing solution, a basic aqueous solution, and an ammonium ion-containing solution are introduced into a batch reactor and stirred to cause a co-precipitation reaction, thereby producing a reaction slurry containing a positive electrode active material precursor. At this time, when the input flow rates of each component during the co-precipitation reaction and the stirring speed in the nucleus generation and growth stages of the precursor are each controlled to a constant level according to the present invention, the formation of precursor fine particles in the nucleus growth stage is minimized, thereby producing a positive electrode active material precursor having a target particle size and a uniform particle size distribution. As a result, the target physical properties of the positive electrode active material, such as tap density and specific surface area, are realized, thereby improving the charge / discharge capacity performance of the battery.

[0036] According to the present invention, before introducing a transition metal-containing solution, a basic aqueous solution, and an ammonium ion-containing solution into a batch reactor, deionized water is introduced into the batch reactor, and nitrogen (N2) gas is purged to remove dissolved oxygen in the water, thereby creating a non-oxidizing atmosphere within the reactor. This non-oxidizing atmosphere within the reactor can be maintained until the completion of the co-precipitation reaction.

[0037] Next, a transition metal-containing solution, a basic aqueous solution, and an ammonium ion-containing solution can be continuously supplied to the batch reactor through an inlet provided in the batch reactor. The transition metal-containing solution, the basic aqueous solution, and the ammonium ion-containing solution are mixed inside the batch reactor to form a reaction solution, and a positive electrode active material precursor particle can be formed through a co-precipitation reaction of the reaction solution.

[0038] A batch reactor may be equipped with a stirrer, as illustrated in Figure 1. The stirrer may be an impeller, but is not limited thereto. In the present invention, the use of a three-stage impeller as the stirrer has the advantage of evenly stirring the reaction slurry from the bottom to the top.

[0039] Hereinafter, each step of the precursor manufacturing method according to the present invention will be described in more detail.

[0040] Nucleation stage (Stage 1)

[0041] The first step is to generate nuclei of the positive electrode active material precursor. Specifically, by introducing a solution of a transition metal compound, a solution of a nitrogen-containing compound, and a solution of a basic compound into a batch reactor and stirring them, the transition metals in the solution of the transition metal compound are coprecipitated, thereby generating precursor particle nuclei in the form of transition metal hydroxides. At this time, the nuclei of the precursor particles have an average particle diameter D. 50 This refers to particles having a size of 1.2 ㎛ to 6 ㎛, specifically 1.5 ㎛ to 5.5 ㎛.

[0042] The stirring speed in the reactor in the first stage may be 200 rpm to 875 rpm, preferably 300 rpm to 850 rpm, and more preferably 500 rpm to 800 rpm. If the stirring speed in the first stage is less than 200 rpm, there is a problem that stirring is not sufficient between the input components, which delays the particle formation time and reduces the yield. If the stirring speed in the first stage exceeds 875 rpm, there is a problem that agglomeration between fine particles is difficult to occur, which prevents the precursor nuclei from being properly formed.

[0043] The pH of the reaction solution in the first step may be 10.5 to 13.5, preferably 10.8 to 13.0, and more preferably 11.0 to 12.8. When the pH of the reaction solution in the first step is within the above numerical range, initial particle formation can be controlled. The pH of the reaction solution can be controlled through the input flow rates of the transition metal compound solution, the nitrogen-containing compound solution, and / or the basic compound solution.

[0044] The co-precipitation reaction in the first step can be performed for 0.5 hours or more, preferably 0.5 to 10 hours, and more preferably 0.5 to 7 hours. When the co-precipitation reaction time in the first step falls within the above numerical range, precursor nuclei of a certain composition are sufficiently formed, thereby increasing the yield of the positive electrode active material precursor.

[0045] The coprecipitation reaction in the first step can be performed at a temperature of 40°C to 60°C under an inert atmosphere such as nitrogen or argon. When the above temperature range is satisfied, the coprecipitation reaction rate can be controlled.

[0046] The transition metal compound solution may contain at least one element selected from the group consisting of nickel, cobalt, and manganese. For example, the transition metal compound solution may contain a nickel-cobalt-manganese compound.

[0047] A transition metal compound solution according to one embodiment of the present invention may contain nickel in an amount of 60 mol% to 96 mol%, preferably 80 mol% to 96 mol%, cobalt in an amount of 0 mol% to 20 mol%, preferably 0 mol% to 10 mol%, and manganese in an amount of 4 mol% to 40 mol%, preferably 4 mol% to 20 mol%. When the contents of nickel, cobalt, and manganese in the transition metal compound solution satisfy the above numerical ranges, the capacity per unit volume and energy density of the battery are increased, thereby having the effect of increasing the single-charge driving distance in the case of an electric vehicle.

[0048] A transition metal compound solution can be prepared by dissolving a transition metal-containing raw material in a solvent such as water. At this time, from a productivity perspective, the concentration of the transition metal compound solution may be 1.80 M to 2.65 M, preferably 2.00 M to 2.55 M. The input amount of each transition metal-containing raw material can be determined by considering the molar ratio between transition metals in the cathode active material to be ultimately prepared.

[0049] The transition metal-containing raw material may include, but is not limited to, acetates, carbonates, nitrates, sulfates, halides, sulfides, oxides, hydrates, hydroxides, and / or oxyhydroxides of the transition metal. Preferably, the transition metal-containing raw material may include hydrates of the transition metal, which have the advantage of being easy to store and use.

[0050] The transition metal compound solution can be prepared by dissolving nickel-containing raw materials, cobalt-containing raw materials, and manganese-containing raw materials in water. The nickel-containing raw materials can be Ni(OH)2, NiO, NiOOH, NiCO3·2Ni(OH)2·4H2O, NiC2O2·2H2O, Ni(NO3)2·6H2O, NiSO4, NiSO4·6H2O, fatty acid nickel salts, nickel halides, or a combination thereof. The cobalt-containing raw materials can be CoSO4, Co(OH)2, CoOOH, Co(OCOCH3)2ㆍ4H2O, Co(NO3)2ㆍ6H2O, CoSO4ㆍ7H2O, Co(SO4)2ㆍ7H2O, or a combination thereof. The manganese-containing raw material may be manganese oxides such as Mn2O3, MnO2, and Mn3O4, manganese salts such as MnCO3, Mn(NO3)2, MnSO4, MnSO4ㆍH2O, manganese acetate, manganese dicarboxylic acid salt, manganese citrate, and manganese fatty acid salt, oxyhydroxide, manganese chloride, or a combination thereof. For example, NiSO4ㆍ6H2O can be used as a nickel-containing raw material, CoSO4ㆍ7H2O can be used as a cobalt-containing raw material, and MnSO4ㆍH2O can be used as a manganese-containing raw material.

[0051] When the positive electrode active material precursor further includes a metal element (M) other than nickel (Ni), manganese (Mn), and cobalt (Co), a raw material containing the metal element (M) may be optionally further added when preparing a transition metal compound solution. The metal element (M) may include at least one element selected from the group consisting of W, Y, Ba, Ca, Mo, Cr, Al, Zr, Ti, Mg, Ta, and Nb. In addition, the raw material containing the metal element (M) may include, but is not limited to, an acetate, a carbonate, a nitrate, a sulfate, a halite, a sulfide, a hydroxide, an oxyhydroxide, and / or an oxide of the metal element (M).

[0052] The nitrogen-containing compound solution may include an ammonium cation complex forming agent. The ammonium cation complex forming agent may include 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 may be prepared by dissolving the ammonium cation complex forming agent in a solvent. In this case, water or a mixture of water and an organic solvent (e.g., alcohol, etc.) may be used as the solvent. The concentration of the nitrogen-containing compound solution may be 1 wt% to 50 wt%, preferably 5 wt% to 25 wt%, and in this case, there is an effect of suppressing the formation of fine particles.

[0053] The basic aqueous solution may contain at least one selected from the group consisting of alkali metal hydrates, alkali metal hydroxides, alkaline earth metal hydrates, and alkaline earth metal hydroxides. For example, the basic aqueous solution may 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 may be 5 wt% to 50 wt%, preferably 10 wt% to 45 wt%, in which case pH control is easy.

[0054] Nuclear growth stage (stage 2)

[0055] The second stage is a stage in which the nuclei generated by the first stage grow. Specifically, the second stage is a stage in which, according to Ostwald ripening, relatively small particles among the nuclei generated by the first stage disappear and the average particle size of relatively large particles increases.

[0056] According to the present invention, the average particle diameter D of the precursor nuclei produced by the first step 50When this reaches 1.2 ㎛ to 6.0 ㎛, the second step can be performed. In the second step, the input flow rates of the transition metal compound solution, the nitrogen-containing compound solution, and the basic compound solution into the batch reactor are maintained the same as in the first step, but the stirring speed and pH are different from those in the first step.

[0057] According to the precursor manufacturing method of the present invention, at the beginning of the second step, the average particle diameter D of the precursor particles 50 It can grow by 0.5㎛ to 1.5㎛ every 5 hours, and in the later stage of the second stage, the average particle diameter of the precursor particles is D 50 This can grow by 0.1 to 0.3 μm every 5 hours. In the later stage of the second stage, as the particle size distribution of the precursor in the reaction solution becomes more uniform, the span value of the precursor particles can gradually decrease.

[0058] The stirring speed in the reactor in the second stage may be 475 rpm or less, preferably 100 rpm to 475 rpm, and more preferably 200 rpm to 450 rpm. If the stirring speed in the second stage exceeds 475 rpm, a large number of precursor fine particles are generated in the nucleus growth stage due to the predominance of side reactions rather than nucleus growth reactions, thereby causing the particle size distribution of the precursor to become non-uniform, or the average particle diameter D of the precursor 50 There is a problem that the co-precipitation reaction time required to reach 5 ㎛ to 25 ㎛ increases.

[0059] The pH of the reaction solution in the second step may be 10.5 to 13.0, preferably 10.8 to 12.5, and more preferably 11.0 to 12.2. When the pH of the reaction solution in the second step is within the above numerical range, the nucleus growth reaction is dominant over the nucleus formation reaction. The pH of the reaction solution can be controlled through the input flow rates of the transition metal compound solution, the nitrogen-containing compound solution, and / or the basic compound solution.

[0060] The ammonia concentration in the reaction solution in the second step may be 3,000 ppm to 7,000 ppm, preferably 3,200 ppm to 6,500 ppm, and more preferably 3,400 ppm to 6,000 ppm. If the ammonia concentration is less than 3,000 ppm, there is a problem that new nuclei are generated and fine particles are generated in the reaction solution, and if the ammonia concentration exceeds 7,000 ppm, there is a problem that nickel forms a new complex with ammonia and fine particles are generated in the reaction solution. The ammonia concentration in the reaction solution can be controlled through the input flow rate of the nitrogen-containing compound solution.

[0061] The co-precipitation reaction in the second step can be performed for 12 hours or more, preferably 15 to 70 hours, and more preferably 18 to 60 hours. When the co-precipitation reaction time in the second step falls within the above numerical range, there is an effect of producing a positive electrode active material precursor having a target sufficient average particle diameter while having a constant particle size distribution.

[0062] The coprecipitation reaction in the second step can be carried out at a temperature of 40°C to 60°C under an inert atmosphere such as nitrogen or argon. When the above temperature range is satisfied, the coprecipitation reaction rate can be controlled.

[0063] Meanwhile, the flow rate of the transition metal compound solution injected into the batch reactor in the first and second steps may be 15 mL / min to 55 mL / min, preferably 16 mL / min to 50 mL / min, and more preferably 18 mL / min to 45 mL / min. If the flow rate of the transition metal compound solution injected in the first and second steps is less than 15 mL / min, there is a problem of deterioration in productivity, and if it exceeds 55 mL / min, there is a problem of occurrence of side reactions.

[0064] The input flow rate of the nitrogen-containing compound solution in the first and second steps may be 1.0 mL / min to 10.0 mL / min, preferably 1.2 mL / min to 8.0 mL / min, and more preferably 1.5 mL / min to 5.0 mL / min. When the above numerical range is satisfied, nucleation control is possible while maintaining the ammonia concentration in the reaction solution at an appropriate level.

[0065] The input flow rate of the basic compound solution in the first and second steps may be 8.0 mL / min to 32.0 mL / min, preferably 9.0 mL / min to 29.0 mL / min, and more preferably 10.0 mL / min to 26.0 mL / min. When the above numerical range is satisfied, the transition metal compound solution can be coprecipitated while maintaining the pH of the reaction solution at an appropriate level.

[0066] When the co-precipitation reaction is carried out according to the first and second steps, when the batch reactor is full of the reaction solution, the addition of each component and the rotation of the stirrer are stopped, and the mixture is left for 1 hour to allow precipitation to proceed. Thereafter, the positive electrode active material precursor particles and the supernatant of the reaction solution are separated. At this time, when the supernatant is separated and discharged, the discharge speed and discharge amount of the supernatant can be adjusted so that the upper part of the stirrer is submerged to a depth of 2 cm or more from the surface of the reaction solution to prevent the stirrer from causing friction on the surface of the reaction solution during subsequent re-stirring, thereby preventing the formation of fine particles.

[0067] For the positive electrode active material precursor produced through the first step and the second step, the span value according to the following equation 1 may be 0.55 or less, preferably 0.50 or less, and more preferably 0.20 to 0.50.

[0068] [Formula 1]

[0069] Span = (particle diameter D) 90 - Particle diameter D 10 ) / average particle diameter D 50

[0070] When the span value of the generated precursor satisfies the above numerical range, the particle size deviation of the precursor particles is small, so that the target properties of the precursor, such as tap density and specific surface area, can be achieved, and the charge / discharge capacity of the positive electrode active material can also be improved.

[0071] Meanwhile, the precursor manufacturing method according to the present invention may further include a washing and drying step (third step) after the first and second steps described above.

[0072] Washing and drying stage (Stage 3)

[0073] The third step is to wash and dry the positive electrode active material precursor produced through the first and second steps. This is to separate the positive electrode active material precursor from the reaction solution and obtain the positive electrode active material precursor.

[0074] Average particle diameter D of precursors produced through steps 1 and 2 50 When the precursor particle size reaches 5 ㎛ to 25 ㎛, specifically 6 ㎛ to 22 ㎛, and more specifically 7 ㎛ to 20 ㎛, a step of washing the precursor may be performed. At this time, the reaction solution may be transferred to equipment used in a filter press process for washing the precursor. The filter press process may refer to a process of washing the reaction solution by forcing it into a sealed filtration chamber and separating the solid (cake) and the liquid (filtrate) through a filter medium. Next, when the washing of the separated precursor particles is completed, nitrogen, argon, oxygen, compressed air, etc. may be supplied at a pressure of 0.4 MPa to dehydrate the supernatant and the washing solution.

[0075] Once the periodic treatment of the precursor is completed, a step of drying the precursor may be performed to remove moisture within the positive electrode active material precursor. The drying treatment of the precursor may be performed so that the moisture content within the precursor is 1.0 wt% or less, preferably 0.8 wt% or less, relative to the total weight of the precursor. When the moisture content satisfies the above range, the productivity and production quality of subsequent processes are effectively improved.

[0076] In addition, the precursor manufacturing method according to the present invention may additionally perform a grinding process and / or a classification process as needed.

[0077] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0078] Examples and Comparative Examples

[0079] Example 1

[0080] (1) Nucleation stage (Stage 1)

[0081] NiSO4ㆍ6H2O hydrate, CoSO4ㆍ7H2O hydrate, and MnSO4ㆍH2O hydrate were mixed in deionized water in an amount such that the molar ratio of nickel: cobalt: manganese was 88:5.0:7.0, thereby preparing a transition metal compound solution with a concentration of 2.4 M.

[0082] 15 L of deionized water was introduced into a 30 L batch reactor, and nitrogen (N2) gas was purged at a flow rate of 5 mL / min to remove dissolved oxygen in the water and create a non-oxidizing atmosphere inside the reactor. Thereafter, while nitrogen gas was purged into the reactor at a flow rate of 5 mL / min, the transition metal compound solution was introduced at a flow rate of 37.50 mL / min, a 25 wt% NaOH solution was introduced at a flow rate of 21.82 mL / min, and a 9 wt% NH4OH solution was introduced at a flow rate of 3.41 mL / min.

[0083] At this time, the temperature of the batch reactor was adjusted to 50°C, the pH of the reaction solution to 11.8, and the stirring speed by the impeller to 750 rpm.

[0084] The co-precipitation reaction at the nucleation stage continued for 1 hour.

[0085] (2) Nuclear growth stage (stage 2)

[0086] After the first step was completed, a 1N sulfuric acid solution was added to the batch reactor so that the pH of the reaction solution became 11.2, and the stirring speed by the impeller was changed to 400 rpm.

[0087] After extracting 100 mL of the reaction solution every 5 hours, ammonia titration was performed, and NH4OH solution was additionally added when the ammonia concentration decreased so that the ammonia concentration in the reaction solution was maintained at 4,000 ppm.

[0088] Meanwhile, during the first and second stages, 50 ml of the reaction solution was extracted every hour, and it was confirmed that the pH of the reaction solution was maintained at 11.2 at room temperature of 25°C. After measuring the pH of the extracted reaction solution, it was returned to the reactor. In addition, it was confirmed that the pH of the reaction solution was maintained at 10.75 at 50°C through an electrode installed in the reactor.

[0089] When the coprecipitation reaction was carried out according to the first and second steps, when the 30 L reactor was full, the addition of each component and the rotation of the impeller were stopped, and the reactor was left for 1 hour to allow precipitation to proceed, and then the NCM precursor and the supernatant were separated. At this time, the supernatant was discharged in an amount of 10 to 12 L, and the discharge speed and amount were controlled so that the upper part of the impeller was submerged to a depth of 2 cm or more from the surface of the coprecipitation reaction solution when discharging the supernatant so that the impeller did not cause friction on the surface of the reaction solution.

[0090] (3) Washing and drying stage (Stage 3)

[0091] The average particle diameter D of the precursor is obtained by carrying out the coprecipitation reaction through the first and second steps. 50 When it reached 5 ㎛ to 25 ㎛, the reaction solution was transferred to the filter press process. In the filter press process, the reaction solution was forced into a sealed filtration chamber, and the solid (cake) and liquid (filtrate) were separated through the filter medium, and a washing treatment was performed. Next, when the washing treatment of the separated precursor particles was completed, nitrogen, argon, oxygen, compressed air, etc. were supplied at a pressure of 0.4 MPa to dehydrate the supernatant and washing solution.

[0092] After the filter press and washing process, the positive electrode active material precursor was dried at 150°C for 8 hours so that the moisture content in the positive electrode active material precursor was 0.5 wt% or less.

[0093] Example 2

[0094] A cathode active material precursor was prepared in the same manner as in Example 1, except that a 2.4 M concentration transition metal compound solution was introduced at a flow rate of 18.03 mL / min, a 25 wt% concentration NaOH solution was introduced at a flow rate of 11.33 mL / min, and a 9 wt% concentration NH4OH solution was introduced at a flow rate of 1.86 mL / min.

[0095] Comparative Example 1

[0096] A positive electrode active material precursor was prepared in the same manner as in Example 1, except that the stirring speed in the first stage was 750 rpm, the stirring speed in the second stage was 625 rpm for the first 15 hours, and then 500 rpm until the end.

[0097] Comparative Example 2

[0098] A solution of a transition metal compound having a concentration of 2.4 M was introduced at a flow rate of 18.03 mL / min, a solution of a NaOH solution having a concentration of 25 wt% was introduced at a flow rate of 11.33 mL / min, and a solution of a NH4OH solution having a concentration of 9 wt% was introduced at a flow rate of 1.86 mL / min. A positive electrode active material precursor was manufactured in the same manner as in Example 1, except that the stirring speed in the first step was 625 rpm and the stirring speed in the second step was 625 rpm.

[0099] Experimental Example 1: SEM Image Analysis of Precursor

[0100] During the first and second steps of Examples 1 and 2 and Comparative Examples 1 and 2, 50 ml of the reaction solution was extracted and dried every 5 hours, and then SEM images of the precursor were taken.

[0101] Figure 2 is an SEM image taken after drying the extracted positive electrode active material precursor after performing a co-precipitation reaction for 48 hours according to Example 1 of the present invention.

[0102] Figure 3 is an SEM image taken after drying the extracted positive electrode active material precursor after performing a co-precipitation reaction for 34 hours according to Example 2 of the present invention.

[0103] Figure 4 is an SEM image taken after drying the extracted positive electrode active material precursor after performing a co-precipitation reaction for 55 hours according to Comparative Example 1 of the present invention.

[0104] Figure 5 is an SEM image taken after drying the extracted positive electrode active material precursor after performing a co-precipitation reaction for 55 hours according to Comparative Example 2 of the present invention.

[0105] According to FIGS. 2 to 5, in Examples 1 and 2, where the stirring speed in the first stage is 200 rpm to 875 rpm and the stirring speed in the second stage is 475 rpm or less, it can be confirmed that the number of fine particles observed in the SEM images is significantly less than in Comparative Examples 1 and 2, where the stirring speed in the second stage is outside the above range.

[0106] Experimental Example 2: Particle size and composition analysis of precursors

[0107] During the first and second steps of Examples 1 and 2 and Comparative Examples 1 and 2, 50 ml of the reaction solution was extracted every 5 hours, and then the particle size and composition of the precursor were analyzed.

[0108] Specifically, particle size analysis was performed under wet conditions using a Mastersizer 2000 device from Malvern.

[0109] Composition analysis was performed under inductively coupled plasma conditions using an Agilent 5900 ICP-OES instrument from Agilent.

[0110] The results of analyzing the particle size and composition of the precursor in the reaction solution extracted in Examples 1 and 2 and Comparative Examples 1 and 2 are shown in Table 1 below.

[0111] Item Unit Example 1 Example 2 Comparative Example 1 Comparative Example 2 Input Flow Transition Metal Compound ml / min 37.50 18.03 37.50 18.03 NaOH 2 1.82 11.33 21.82 11.33 NH4OH 3.4 11.86 3.4 11.86 Rotation Manual 1st stage rpm 750 750 750 625 2nd stage 400 400 625 -> 500 625 Particle size analysis D 50 ㎛10.010.0010.2010.32D 10 8.107.807.618.33D 90 12.4512.6413.3413.07D min 4.03.503.204.00D max16.716.7017.9017.90Span-0.440.480.560.46CompositionNimol%88.187.987.888.0Co4.95.05.14.9Mn7.17.27.17.1Coprecipitation reaction timehr48343455

[0112] According to Table 1, in Examples 1 and 2, where the stirring speed in the first stage is 200 rpm to 875 rpm and the stirring speed in the second stage is 475 rpm or less, it can be confirmed that the Span value is lower or the co-precipitation reaction time is shorter than in Comparative Examples 1 and 2, where the stirring speed in the second stage is outside the above range. From this, it can be confirmed that the particle size distribution of the precursors manufactured in Examples 1 and 2 is more uniform than in Comparative Example 1, and that the co-precipitation reaction time required for the preparation of the precursor in Examples 1 and 2 is significantly shorter than in Comparative Example 2.

[0113] While the present invention has been described in connection with certain embodiments herein, it should be understood that various modifications and variations can be made without departing from the spirit and scope of the invention, as understood by those skilled in the art. Furthermore, such modifications and variations are intended to fall within the scope of the claims appended to this specification.

Claims

1. A method for manufacturing a positive electrode active material precursor, A first step of generating the nucleus of the above precursor; and A second step of growing the nucleus generated by the first step is included, In the first and second steps, the flow rate of the transition metal compound solution introduced into the batch reactor is 15 mL / min to 55 mL / min, The stirring speed in the reactor in the first step is 200 rpm to 875 rpm, A manufacturing method wherein the stirring speed inside the reactor in the second step is 475 rpm or less.

2. In paragraph 1, A manufacturing method, wherein the above transition metal compound solution contains at least one element selected from the group consisting of nickel, cobalt and manganese.

3. In paragraph 1, The above transition metal compound solution is, 60 mol% to 96 mol% nickel; 0 mol% to 20 mol% cobalt; and A manufacturing method comprising 4 mol% to 40 mol% of manganese.

4. In paragraph 1, A manufacturing method, wherein the reaction solution inside the batch reactor in the first step has a pH of 10.5 to 13.

5.

5. In paragraph 1, A manufacturing method, wherein the reaction solution inside the batch reactor in the second step has a pH of 10.5 to 13.

5.

6. In paragraph 1, A manufacturing method, wherein the reaction solution inside the batch reactor in the second step has an ammonia concentration of 3,000 ppm to 7,000 ppm.

7. In paragraph 1, A manufacturing method wherein the input flow rate of the nitrogen-containing compound solution in the first step and the second step is 1.0 mL / min to 10.0 mL / min.

8. In paragraph 1, A manufacturing method wherein the input flow rate of the basic compound solution in the first step and the second step is 8.0 mL / min to 32.0 mL / min.

9. In paragraph 1, A manufacturing method wherein the positive electrode active material precursor produced through the first and second steps has a span value of 0.55 or less according to the following equation 1. [Formula 1] Span = (particle diameter D) 90 - Particle diameter D 10 ) / Average particle diameter D 50 10. In paragraph 1, A manufacturing method further comprising a third step of washing and drying the positive electrode active material precursor produced through the first step and the second step.

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