Manufacturing method for positive electrode active material precursor

Abstract

A manufacturing method for a positive electrode active material precursor using a batch reactor according to the present invention comprises the steps of: (S1) producing nuclei of the precursor; (S2) growing the nuclei produced in step S1; (S3) further growing the precursor particles grown in step S2; and (S4) further growing the precursor particles grown in step S3, wherein the agitation speed in the batch reactor is 200-900rpm in step S2, 800rpm or less in step S3, and 700rpm or less in step S4, and when the batch reactor is full, the reaction solution is allowed to overflow.

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 an overflow method in 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, posing a problem. In this case, the physical properties of the cathode active material 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 methods such as an Air Classifier Mill (ACM) or an Air Jet Mill to control the influence of the aforementioned precursor fine particles, 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 it 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 positive electrode active materials due to increased costs and overall process time due to additional processes / equipment.

[0007] Meanwhile, as the average particle size of precursor particles increases during the precursor manufacturing process, surface cracking due to particle-to-particle collisions has become a problem. This phenomenon, when cracks form on the precursor particle surface, lowers the press density, potentially leading to additional cracking during the electrode rolling process during the production of the cathode active material. This, in turn, can lead to side reactions with the electrolyte and deteriorate battery performance.

[0008] The present invention is intended to solve the above problem, and its purpose is to provide a precursor manufacturing method capable of implementing a uniform particle size distribution by minimizing the formation of precursor fine particles during the precursor nucleus growth step and preventing the problem of cracks occurring on the surface of precursor particles.

[0009] A method for producing a positive electrode active material precursor using a batch reactor according to one aspect of the present invention comprises: (S1) a step of generating nuclei of the precursor; (S2) a step of growing nuclei generated by the step S1; (S3) a step of further growing precursor particles grown by the step S2; and (S4) a step of further growing precursor particles grown by the step S3, wherein a stirring speed in the batch reactor is 200 rpm to 900 rpm in the step S2, 800 rpm or less in the step S3, and 700 rpm or less in the step S4, and a reaction solution is allowed to overflow when the inside of the batch reactor is full.

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

[0011] According to one aspect of the present invention, after the end of the S3 step, the average particle diameter D of the precursor 50 may be 6.5㎛ to 13.0㎛.

[0012] According to one aspect of the present invention, the stirring speed in the batch reactor in the step S1 may be 250 rpm to 1,000 rpm.

[0013] According to one aspect of the present invention, the flow rate of the transition metal compound solution injected into the batch reactor may be 5 mL / min to 40 mL / min in the S2 and S3 steps, and 2 mL / min to 30 mL / min in the S4 step.

[0014] 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.

[0015] 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.

[0016] According to one aspect of the present invention, the input flow rate of the nitrogen-containing compound solution may be 1.0 mL / min to 10.0 mL / min in the S2 and S3 steps, and 1.2 mL / min to 8.0 mL / min in the S4 step.

[0017] According to one aspect of the present invention, the input flow rate of the basic compound solution may be 3 mL / min to 35 mL / min in the steps S2 and S3, and 2 mL / min to 30 mL / min in the step S4.

[0018] According to one aspect of the present invention, the reaction solution inside the batch reactor in the step S1 may have a pH of 10.5 to 13.5.

[0019] According to one aspect of the present invention, in the S2 step, the S3 step, and the S4 step, the reaction solution inside the batch reactor may have a pH of 10.5 to 13.0.

[0020] According to one aspect of the present invention, in the S2 step, the S3 step, and the S4 step, the ammonia concentration in the reaction liquid inside the batch reactor may be 3,000 ppm to 7,000 ppm.

[0021] According to one aspect of the present invention, in the S2 step, the S3 step, and the S4 step, the concentration of residual nickel in the reaction liquid inside the batch reactor may be 250 ppm or less.

[0022] According to one aspect of the present invention, the positive electrode active material precursor produced through the steps S1 to S4 may have a span value of 0.38 or less according to the following equation 1.

[0023] [Formula 1]

[0024] Span = (particle diameter D) 90 - Particle diameter D 10 ) / average particle diameter D 50

[0025] According to one aspect of the present invention, (S5) a step of washing and drying the positive electrode active material precursor produced through the steps S1 to S4 may be further included.

[0026] The present invention overflows the reaction solution through a discharge line when the batch reactor is full of the reaction solution during the co-precipitation reaction of the precursor. As a result, the precursor ratio within the reactor is controlled to induce uniform growth of the precursor, thereby preventing the problem of cracks occurring on the surface of the precursor particles. In addition, when the overflow method is used, the solid density within the reactor can be controlled by adjusting the amount of the reaction solution injected and the amount of the reaction solution discharged, so that even in a limited space within the reactor, the particle size distribution is uniform and the average particle diameter D 50 It is possible to manufacture large precursor particles of 7㎛ to 30㎛ in size.

[0027] In addition, the present invention controls the stirring speed in the precursor nucleus growth stage (S2 to S4) to a specific numerical range, thereby controlling the average particle diameter D 50 When manufacturing large precursor particles of 7 to 30 μm in size, cracks on the particle surface that may occur due to collisions between particles can be prevented. As a result, cracks on the surface of the active material particles can be prevented during the rolling process when manufacturing positive electrode active materials from the precursor.

[0028] According to the precursor manufacturing method of the present invention, the formation of fine particles in the reaction solution is minimized during the nucleus growth steps (S2 to S4). As a result, a positive electrode active material precursor having a targeted particle size and uniform particle size distribution can be manufactured. Furthermore, since a separate process for removing fine particles is not required, the overall process time can be significantly reduced, process costs can be reduced, and thus line configuration efficiency can be improved, thereby increasing the production yield of positive electrode active materials.

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

[0030] Figure 2 is an SEM image taken after drying the extracted positive electrode active material precursor after performing a co-precipitation reaction for 50 hours according to Example 1 of the present invention.

[0031] Figure 3 is an SEM image taken after drying the extracted positive electrode active material precursor after performing a co-precipitation reaction for 50 hours according to Example 2 of the present invention.

[0032] Figures 4, 5, 6 and 7 are SEM images taken after drying the extracted positive electrode active material precursor after performing a co-precipitation reaction for 110 hours according to Comparative Example 1 of the present invention.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] In this disclosure, the description of “A and / or B” means A, or B, or A and B.

[0039] 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.

[0040] A method for manufacturing a positive electrode active material precursor using a batch reactor according to the present invention comprises: (S1) a step of generating nuclei of the precursor; (S2) a step of growing nuclei generated by step S1; (S3) a step of further growing nuclei grown by step S2; and (S4) a step of further growing nuclei grown by step S3, wherein a stirring speed in the batch reactor is 200 rpm to 900 rpm in step S2, 800 rpm or less in step S3, and 700 rpm or less in step S4, and a reaction solution is allowed to overflow when the inside of the batch reactor is full.

[0041] Figure 1 is an exemplary diagram of a method for manufacturing a positive electrode active material precursor according to the present invention. As illustrated in Figure 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 manufacturing a reaction slurry containing a positive electrode active material precursor.

[0042] 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 an inert gas (e.g., nitrogen and / or argon) 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 coprecipitation reaction.

[0043] 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.

[0044] 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.

[0045] Hereinafter, each step of the precursor manufacturing method according to the present invention will be described in more detail.

[0046] Nucleation stage (S1 stage)

[0047] Step S1 is the step of generating nuclei of the positive electrode active material precursor. Specifically, when a solution of a transition metal compound, a solution of a nitrogen-containing compound, and a solution of a basic compound are introduced into a batch reactor and stirred, 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 6.0 ㎛, specifically 1.5 ㎛ to 5.5 ㎛.

[0048] The stirring speed in the reactor at step S1 may be 250 rpm to 1,000 rpm, preferably 350 rpm to 900 rpm, and more preferably 450 rpm to 850 rpm. When the stirring speed at step S1 satisfies the above numerical range, it has the effect of inducing uniform nucleation.

[0049] The pH of the reaction solution in step S1 may be 10.5 to 13.5, preferably 10.7 to 13.3, and more preferably 10.8 to 13.0. When the pH of the reaction solution in step S1 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.

[0050] The co-precipitation reaction in step S1 can be performed at a temperature of 40°C to 60°C under an inert atmosphere such as nitrogen and / or argon. When the above temperature range is satisfied, the co-precipitation reaction rate can be controlled.

[0051] The flow rate of the transition metal compound solution introduced into the batch reactor in step S1 may be 2 mL / min to 35 mL / min, preferably 3 mL / min to 30 mL / min, and more preferably 4 mL / min to 25 mL / min. When the above numerical range is satisfied, the solid density within the reactor can be controlled to favor the nucleus growth reaction.

[0052] The transition metal compound solution may include at least one element selected from the group consisting of nickel, cobalt, and manganese. For example, the transition metal compound solution may include a nickel-cobalt-manganese compound.

[0053] 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, there is an effect of increasing the energy density during battery manufacturing.

[0054] 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.

[0055] 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.

[0056] 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 CoSO 4, 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.

[0057] 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).

[0058] The input flow rate of the nitrogen-containing compound solution in step S1 may be 1.0 mL / min to 10 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.

[0059] A nitrogen-containing compound solution can act as a complexing agent to help the coprecipitation reaction between each transition metal in a transition metal compound solution.

[0060] 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. At this time, 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%, in which case the ammonia concentration in the reactor can be appropriately controlled.

[0061] In step S1, the input flow rate of the basic compound solution may be 2.0 mL / min to 30.0 mL / min, preferably 2.5 mL / min to 25.0 mL / min, and more preferably 2.8 mL / min to 20.0 mL / min. When the above numerical range is satisfied, constant nucleation can be induced while maintaining the pH of the reaction solution at an appropriate value.

[0062] The basic aqueous solution may include 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 it is easy to maintain the reaction solution at an appropriate pH.

[0063] The co-precipitation reaction in step S1 can be performed for 0.5 hours or longer, preferably 0.5 to 10 hours, and more preferably 0.5 to 8 hours. That is, step S1 can be completed when the co-precipitation reaction time has elapsed. When the co-precipitation reaction time in step S1 falls within the above numerical range, precursor nuclei of a certain composition are sufficiently formed, thereby having the effect of increasing the yield of the positive electrode active material precursor.

[0064] Nuclear growth stage (S2 to S4 stages)

[0065] Steps S2 to S4 are steps for growing nuclei generated by step S1. Specifically, step S2 is a step for growing nuclei generated by step S1, step S3 is a step for further growing precursor particles grown by step S2, and step S4 is a step for further growing precursor particles grown by step S3.

[0066] Stages S2 to S4 may be stages in which relatively small particles among the nuclei generated by stage S1 disappear and the average particle size of relatively large particles increases according to Ostwald ripening. In the early stages of stages S2 to S4, the average particle size of the precursor particles D 50 It can grow by 0.5㎛ to 1.5㎛ every 5 hours, and in the later stages of S2 to S4, the average particle diameter of the precursor particles is D 50 This can grow by 0.1㎛ to 0.3㎛ every 5 hours. In the later stages of S2 to S4, the Span value of the precursor particles can gradually decrease as the particle size distribution of the precursor in the reaction solution becomes more uniform.

[0067] The pH of the reaction solution in steps S2 to S4 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 steps S2 to S4 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, the basic compound solution, and / or the acidic compound solution.

[0068] In steps S2 to S4, the ammonia concentration in the reaction solution 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, the formation of transition metal hydrate takes precedence over the coprecipitation reaction, which may result in the generation of new particulates in the reaction solution. If the ammonia concentration exceeds 7,000 ppm, the residual nickel in the reaction solution may form a new complex with ammonia, which may result in the generation of new particulates in the reaction solution. The ammonia concentration in the reaction solution may be controlled by the input flow rate of the nitrogen-containing compound solution.

[0069] When the ammonia concentration in the reaction solution is maintained at 3,000 ppm to 7,000 ppm in steps S2 to S4, the concentration of residual nickel in the solution may tend to gradually increase as the co-precipitation reaction time increases. At this time, the concentration of residual nickel in the reaction solution inside the batch reactor in steps S2 to S4 may be 250 ppm or less, preferably 0 ppm to 225 ppm, and more preferably 0 ppm to 200 ppm. Here, the concentration of residual nickel refers to the concentration of nickel in the solution that is unreacted during the process in which the transition metal compound solution is converted into the positive electrode active material precursor. When the concentration of residual nickel in the reaction solution is within the above numerical range, the formation of new fine particles in the reaction solution can be suppressed according to Le Chatelier's principle. The concentration of residual nickel in the reaction solution can be controlled through the input flow rate of the transition metal compound solution.

[0070] The co-precipitation reaction in steps S2 to S4 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 co-precipitation reaction rate can be controlled.

[0071] When the co-precipitation reaction is carried out according to steps S2 to S4, when the batch reactor is full of the reaction solution, the reaction solution is overflowed through the discharge line. As a result, the solid density inside the reactor is controlled, thereby preventing the problem of cracks occurring on the particle surface. In addition, when the overflow method is used, the solid density inside the reactor can be controlled by controlling the amount of the reaction solution injected and the amount of the reaction solution discharged, so that even in a limited space inside the reactor, the particle size distribution is uniform and the average particle diameter D 50 It is possible to manufacture large precursor particles of 7㎛ to 30㎛ in size.

[0072] Below, each sub-step of the nuclear growth stage is described in detail.

[0073] (1) S2 stage

[0074] The average particle diameter D of the precursor nuclei generated by the S1 stage 50 When this becomes 1.2 ㎛ to 6.0 ㎛, step S2 can be performed. Step S2 is characterized by differentiating the input flow rates of the transition metal compound solution, nitrogen-containing compound solution, and basic compound solution into the batch reactor, as well as the stirring speed and pH compared to step S1.

[0075] The stirring speed in the reactor in step S2 may be 200 rpm to 900 rpm, preferably 225 rpm to 850 rpm, and more preferably 250 rpm to 800 rpm. If the stirring speed in step S2 exceeds 900 rpm, there is a problem that a large number of precursor fine particles are generated in the nucleus growth step because side reactions rather than nucleus growth reactions are dominant, thereby causing an uneven particle size distribution of the precursor. If the stirring speed in step S2 is less than 200 rpm, the aspect ratio of the precursor produced is low, so that the proportion of the precursor in a unit volume during battery production is low, and thus there is a problem that the battery capacity is reduced.

[0076] The flow rate of the transition metal compound solution introduced into the batch reactor in step S2 may be 5 mL / min to 40 mL / min, preferably 7 mL / min to 35 mL / min, and more preferably 10 mL / min to 30 mL / min. When the above numerical range is satisfied, the growth reaction rate of the generated nuclei can be appropriately controlled.

[0077] The input flow rate of the nitrogen-containing compound solution in step S2 may be the same as in step S1. For example, the input flow rate of the nitrogen-containing compound solution in step S2 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.

[0078] In step S2, the input flow rate of the basic compound solution may be 3 mL / min to 35 mL / min, preferably 5 mL / min to 30 mL / min, and more preferably 8 mL / min to 25 mL / min. When the above numerical range is satisfied, the pH of the reaction solution can be maintained within an appropriate numerical range.

[0079] The co-precipitation reaction in step S2 can be carried out for 1 hour or more, preferably 1.5 to 20 hours, and more preferably 2 to 15 hours. That is, step S2 can be completed when the co-precipitation reaction time has elapsed. When the co-precipitation reaction time in step S2 falls within the above numerical range, the aspect ratio of the precursor increases, which can increase the energy density of the battery and has the effect of controlling the differentiation.

[0080] (2) S3 stage

[0081] After step S2 is completed, step S3 can be performed. Step S3 is characterized by a different stirring speed compared to step S2.

[0082] The stirring speed within the reactor in step S3 may be slower than that in step S2. Specifically, the stirring speed within the reactor in step S3 may be 800 rpm or less, preferably 175 rpm to 750 rpm, and more preferably 200 rpm to 700 rpm. If the stirring speed in step S3 exceeds 800 rpm, there is a problem that the Span value increases.

[0083] The flow rate of the transition metal compound solution introduced into the batch reactor in step S3 may be the same as that in step S2. For example, the flow rate of the transition metal compound solution introduced in step S3 may be 5 mL / min to 40 mL / min, preferably 7 mL / min to 35 mL / min, and more preferably 10 mL / min to 30 mL / min.

[0084] The input flow rate of the nitrogen-containing compound solution in step S3 may be the same as in step S2. For example, the input flow rate of the nitrogen-containing compound solution in step S3 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 mL / min.

[0085] The input flow rate of the basic compound solution in step S3 may be the same as in step S2. For example, the input flow rate of the basic compound solution in step S3 may be 3 mL / min to 35 mL / min, preferably 5 mL / min to 30 mL / min, and more preferably 8 mL / min to 25 mL / min.

[0086] The co-precipitation reaction in the S3 step can be performed for, for example, 5 hours or more, preferably 7 to 35 hours, and when the co-precipitation reaction time in the S3 step is in the above numerical range, the average particle diameter D of the precursor particles 50 It can reach 6.5㎛ to 13.0㎛. However, the average particle diameter D of the precursor particles 50 If this 6.5㎛ to 13.0㎛ is not reached, the co-precipitation reaction of the S3 stage can be continued under the same conditions until it is reached.

[0087] After the end of step S3, the average particle diameter D of the precursor particles 50 The average particle diameter D of the precursor particles after the end of step S3 may be 6.5 ㎛ to 13.0 ㎛, preferably 7.5 ㎛ to 12.5 ㎛, and more preferably 8.0 ㎛ to 12.0 ㎛. 50 If it is less than 6.5㎛, the target average particle diameter D 50 There is a problem in manufacturing these large precursor particles. The average particle diameter D of the precursor particles after the end of the S3 step 50If it exceeds 13.0㎛, the number of collisions between particles increases during the co-precipitation reaction due to stirring, which may cause cracks to form on the particle surface. Therefore, in the present invention, the average particle diameter D of the precursor particles 50 When this reaches 6.5㎛ to 13.0㎛, the S3 stage can be terminated and the S4 stage can be performed.

[0088] (3) S4 stage

[0089] The average particle diameter D of precursor nuclei generated by the S3 stage 50 When it reaches 6.5㎛ to 13.0㎛, step S3 is completed and step S4 can be performed. Step S4 is characterized by different input flow rates and stirring speeds of the transition metal compound solution, nitrogen-containing compound solution, and basic compound solution into the batch reactor compared to step S3.

[0090] The stirring speed in the reactor at step S4 may be slower than at steps S2 and S3. Specifically, the stirring speed in the reactor at step S4 may be 700 rpm or less, preferably 150 rpm to 650 rpm, and more preferably 175 rpm to 600 rpm. When the stirring speed at step S4 exceeds 700 rpm, the average particle diameter D increases as the co-precipitation reaction time increases. 50 There is a problem that the number of collisions between these large precursor particles increases, causing cracks to form on the particle surfaces.

[0091] The flow rate of the transition metal compound solution injected into the batch reactor in step S4 may be 2 mL / min to 30 mL / min, preferably 3 mL / min to 25 mL / min, and more preferably 5 mL / min to 20 mL / min. When the above numerical range is satisfied, the average particle diameter D is maintained while suppressing the generation of new fine particles. 50These precursor particles of 6.5 μm to 13.0 μm can be further grown. Since the present invention applies an overflow method during precursor production, even if the input flow rate of the transition metal compound solution is reduced in step S4 compared to steps S2 and S3, the problem of a decrease in the growth rate of the precursor particles can be prevented.

[0092] Considering the flow rate of the transition metal compound solution input in step S4, the flow rate of the nitrogen-containing compound solution input in step S4 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.

[0093] Considering the flow rate of the transition metal compound solution input in step S4, the flow rate of the basic compound solution input in step S4 may be 2 mL / min to 30 mL / min, preferably 3 mL / min to 25 mL / min, and more preferably 4 mL / min to 20 mL / min.

[0094] Meanwhile, in the case of a positive electrode active material precursor produced through steps S1 to S4, the span value according to the following equation 1 may be 0.38 or less, preferably 0.35 or less, and more preferably 0.25 to 0.33.

[0095] [Formula 1]

[0096] Span = (particle diameter D) 90 - Particle diameter D 10 ) / average particle diameter D 50

[0097] 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.

[0098] Meanwhile, the precursor manufacturing method according to the present invention may further include a washing and drying step (step S5) after the steps S1 to S4 described above.

[0099] Washing and drying stage (S5 stage)

[0100] Step S5 is a step of washing and drying the positive electrode active material precursor produced through steps S1 to S4. This is to separate the positive electrode active material precursor from the reaction solution and obtain the positive electrode active material precursor.

[0101] Average particle diameter D of precursors generated through S4 step 50 When the precursor particle size reaches 7 ㎛ to 30 ㎛, specifically 8 ㎛ to 27 ㎛, and more specifically 9 ㎛ to 25 ㎛, 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 process of the separated precursor particles is completed, nitrogen gas may be purged to prevent oxidation of the positive electrode active material precursor.

[0102] 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.

[0103] In addition, the precursor manufacturing method according to the present invention may additionally perform a grinding process and / or a classification process as needed.

[0104] 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.

[0105] Examples and Comparative Examples

[0106] Example 1

[0107] (1) Nucleation stage (S1 stage)

[0108] 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 91:4.5:4.5, thereby preparing a transition metal compound solution with a concentration of 2.4 M.

[0109] 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 4.51 mL / min, a 25 wt% NaOH solution was introduced at a flow rate of 2.84 mL / min, and a 9 wt% NH4OH solution was introduced at a flow rate of 3.00 mL / min.

[0110] 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.

[0111] The co-precipitation reaction in the nucleation stage (S1) is characterized by the average particle diameter D of the precursor particle nuclei. 50 This was continued for 0.5 h until it became 1.2 ㎛ to 6.0 ㎛.

[0112] (2) Nuclear growth stage (S2 stage ~ S4 stage)

[0113] After the completion of step S1, a 1N sulfuric acid solution was added to the batch reactor so that the pH of the reaction solution became 11.2.

[0114] After the completion of step S1, the input flow rates of each component were changed in step S2. Specifically, the transition metal compound solution with a concentration of 2.4 M was input at a flow rate of 18.03 mL / min, the NaOH solution with a concentration of 25 wt% was input at a flow rate of 11.33 mL / min, and the NH4OH solution with a concentration of 9 wt% was input at a flow rate of 3.00 mL / min. The stirring speed by the impeller in step S2 was changed to 400 rpm. The co-precipitation reaction in step S2 continued for 4.5 hours.

[0115] After the completion of the S2 stage, in the S3 stage, the input flow rates of each component were maintained as compared to the S2 stage, but the stirring speed by the impeller was changed to 300 rpm. The co-precipitation reaction in the S3 stage was continued for 15 hours. At this time, the average particle diameter of the precursor particles D 50 If 6.5 μm to 13.0 μm was not reached, the co-precipitation reaction was continued under the same conditions until it was reached.

[0116] After the end of step S3, the input flow rates of each component were changed in step S4. Specifically, the transition metal compound solution with a concentration of 2.4 M was input at a flow rate of 9.02 mL / min, the NaOH solution with a concentration of 25 wt% was input at a flow rate of 5.67 mL / min, and the NH4OH solution with a concentration of 9 wt% was input at a flow rate of 2.10 mL / min. The stirring speed by the impeller in step S4 was changed to 200 rpm. The co-precipitation reaction in step S4 was continued for 30 hours.

[0117] When the inside of the batch reactor became full during steps S2 to S4, the reaction liquid was overflowed through the discharge line.

[0118] During the S2 to S4 steps, 100 mL of the reaction solution was extracted every 5 hours and ammonia titration was performed. When the ammonia concentration decreased, NH4OH solution was additionally added so that the ammonia concentration in the reaction solution was maintained at 4,000 ppm.

[0119] During steps S2 to S4, 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.

[0120] (3) Washing and drying stage (S5 stage)

[0121] After the coprecipitation reaction was carried out for a total of 50 hours through steps S1 to S4, 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 a 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.

[0122] 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.

[0123] Example 2

[0124] A positive electrode active material precursor was manufactured in the same manner as in Example 1, except that the stirring speed by the impeller in step S1 was adjusted to 650 rpm.

[0125] Comparative Example 1

[0126] When the inside of the batch reactor was full during steps S2 to S4, the input of each component and the rotation of the impeller were stopped, the reactor was left for 1 hour to allow sedimentation, and the supernatant was discharged in an amount of 10 to 12 L, thereby separating the NCM precursor and the supernatant. A positive electrode active material precursor was manufactured in the same manner as in Example 1, except that the NCM precursor and the supernatant were separated.

[0127] At this time, the co-precipitation reaction in the S1 stage is the average particle diameter D of the precursor particles. 50 This was continued for 0.5 h until it became 1.2 ㎛ to 6.0 ㎛.

[0128] The co-precipitation reaction at stage S2 continued for 4.5 hours.

[0129] The co-precipitation reaction in the S3 stage is performed with the average particle diameter D of the precursor particles. 50 This was continued for 15 hours until it reached 6.5 ㎛ to 13.0 ㎛.

[0130] The co-precipitation reaction in step S4 is performed on the average particle diameter D of the precursor particles. 50 This was continued for 90 hours until it became 7.0 ㎛ to 30.0 ㎛.

[0131] Experimental Example 1: SEM Image Analysis of Precursor

[0132] During the S2 to S4 steps of Examples 1 to 2 and Comparative Example 1, 50 ml of the reaction solution was extracted and dried every 5 hours, and then SEM images of the precursor were taken.

[0133] Figure 2 is an SEM image taken after drying the extracted positive electrode active material precursor after performing a co-precipitation reaction for 50 hours according to Example 1 of the present invention.

[0134] Figure 3 is an SEM image taken after drying the extracted positive electrode active material precursor after performing a co-precipitation reaction for 50 hours according to Example 2 of the present invention.

[0135] Figures 4, 5, 6 and 7 are SEM images taken after drying the extracted positive electrode active material precursor after performing a co-precipitation reaction for 110 hours according to Comparative Example 1 of the present invention.

[0136] According to FIGS. 2 to 7, in the case of Examples 1 and 2, where the stirring speed is 200 to 900 rpm in step S2, 800 rpm or less in step S3, and 700 rpm or less in step S4, and where overflow is performed when the reactor is full, the number of fine particles observed in the SEM image is significantly less than that of Comparative Example 1, where precipitation separation is performed when the reactor is full of the reaction solution, and it can be confirmed that no surface cracks occur in the precursor particles.

[0137] Experimental Example 2: Particle size and composition analysis of precursors

[0138] During the progress of steps S2 to S4 of Examples 1 to 2 and Comparative Example 1, 50 ml of the reaction solution was extracted every 5 hours, and then the particle size and composition of the precursor were analyzed.

[0139] Specifically, particle size analysis was performed under wet conditions using a Mastersizer 2000 device from Malvern.

[0140] Composition analysis was performed under inductively coupled plasma conditions using an Agilent 5900 ICP-OES instrument from Agilent.

[0141] The results of analyzing the particle size and composition of the precursor in the reaction solution extracted in Examples 1 to 2 and Comparative Example 1 are shown in Table 1 below.

[0142] Item Unit Example 1 Example 2 Comparative Example 1 Rotational speed S1 rpm 750 650 750 S2 400 400 400 S3 300 300 300 S4 200 200 200 Treatment method when the reactor is full - Overflow Overflow Sedimentation Separation Particle size analysis D 50 ㎛13.813.713.8D 10 11.811.711.4D 90 15.716.116.8Dmin 7.37.15.0D max 19.319.322.5Span-0.280.320.39CompositionNimol%91.090.990.9Co4.54.54.4Mn4.54.64.7Co-precipitation reaction timehr5050110

[0143] According to Table 1, in the case of Examples 1 and 2, where the stirring speed was 200 to 900 rpm in the S2 stage, 800 rpm or less in the S3 stage, and 700 rpm or less in the S4 stage, and where overflow was performed when the reactor was full, it can be confirmed that the Span value was lower and the co-precipitation reaction time was shorter than in Comparative Example 1, where precipitation separation was performed when the reactor was full. 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 in the case of Examples 1 and 2, the co-precipitation reaction time required for precursor manufacture is significantly shortened compared to Comparative Example 1.

[0144] 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 cathode active material precursor using a batch reactor, (S1) a step of generating a nucleus of the precursor; (S2) a step of growing the nucleus generated by the above step S1; (S3) a step of further growing the precursor particles grown by the above S2 step; and (S4) comprising a step of further growing the precursor particles grown by the above step S3; The stirring speed in the above batch reactor is, In the above S2 step, 200 rpm to 900 rpm, At the above S3 stage, it is less than 800 rpm, At the above S4 stage, it is less than 700 rpm, A manufacturing method for causing a reaction solution to overflow when the inside of the above batch reactor is full.

2. In paragraph 1, A manufacturing method wherein the co-precipitation reaction in the above S2 step is performed for 1 to 20 hours.

3. In paragraph 1, After the above S3 step is completed, the average particle diameter D of the precursor 50 A manufacturing method wherein the silver is 6.5㎛ to 13.0㎛.

4. In paragraph 1, A manufacturing method wherein the stirring speed in the batch reactor in the above step S1 is 250 rpm to 1,000 rpm.

5. In paragraph 1, The flow rate of the transition metal compound solution injected into the above batch reactor is, In the above S2 step and the above S3 step, the flow rate is 5 mL / min to 40 mL / min, A manufacturing method, wherein the flow rate in step S4 is 2 mL / min to 30 mL / min.

6. In paragraph 5, 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.

7. In paragraph 5, 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.

8. In paragraph 1, The input flow rate of the nitrogen-containing compound solution is: In the above S2 step and the above S3 step, 1.0 mL / min to 10.0 mL / min, A manufacturing method, wherein the flow rate is 1.2 mL / min to 8.0 mL / min in the above step S4.

9. In paragraph 1, The input flow rate of the basic compound solution is: In the above S2 step and the above S3 step, 3 mL / min to 35 mL / min, A manufacturing method, wherein the flow rate in step S4 is 2 mL / min to 30 mL / min.

10. In paragraph 1, A manufacturing method wherein the reaction solution inside the batch reactor in the above step S1 has a pH of 10.5 to 13.

5.

11. In paragraph 1, A manufacturing method wherein, in the above steps S2, S3 and S4, the pH of the reaction solution inside the batch reactor is 10.5 to 13.

0.

12. In paragraph 1, A manufacturing method wherein, in the steps S2, S3, and S4, the ammonia concentration in the reaction solution inside the batch reactor is 3,000 ppm to 7,000 ppm.

13. In paragraph 1, A manufacturing method wherein, in the steps S2, S3 and S4, the concentration of residual nickel in the reaction solution inside the batch reactor is 250 ppm or less.

14. In paragraph 1, A manufacturing method wherein the positive electrode active material precursor produced through the above steps S1 to S4 has a span value of 0.38 or less according to the following equation 1. [Formula 1] Span = (particle diameter D) 90 - Particle diameter D 10 ) / Average particle diameter D 50 15. In paragraph 1, (S5) A manufacturing method further comprising a step of washing and drying the positive electrode active material precursor produced through steps S1 to S4.

Images