Method for manufacturing single-crystal cathode material for lithium secondary battery

Abstract

A cathode material for a lithium secondary battery according to the present invention undergoes heat treatment divided into pre-firing and firing processes, and a lithium halide compound is included in the pre-firing or firing process, thereby enabling a single crystal to be manufactured at a low temperature, and by separating single-crystal particles through a simple separation process, a cathode active material having a single-crystal form can be manufactured. According to the present invention, the effect of reducing manufacturing costs can be obtained by shortening a grinding process of the cathode active material and achieving yield improvement. In addition, the surfaces of the single-crystal cathode active material particles are stabilized, and thus there is an advantage of greatly improving the electrochemical performance of a lithium secondary battery manufactured by using the cathode active material.

Description

Method for manufacturing single-crystal cathode material for lithium secondary batteries

[0001] The present invention relates to a method for producing a single-crystal cathode material for a lithium secondary battery, and more particularly, to a method for producing a single-crystal cathode material for a lithium secondary battery, which enables the production of a single crystal at a low temperature by including a lithium halide compound when synthesizing a ternary (nickel-cobalt-manganese) cathode active material having a high nickel content of 60%, and further facilitates the separation of particles after calcination, thereby facilitating the pulverization process of particles.

[0002] With the recent development of the electrical, electronic, communications, and computer industries, and the rapid development of the eco-friendly vehicle and energy storage markets, the development of high-energy density and low-cost lithium secondary batteries has become very important. Since cathode materials account for the largest proportion of the cost of materials that make up lithium secondary batteries, efforts are being made to increase the capacity of cathode materials and lower their prices.

[0003] Efforts are being made to minimize the cobalt content as much as possible for cathode materials of medium and large-sized lithium secondary batteries from the perspectives of price, safety, and high energy density. Accordingly, cathode active materials of the NCM (nickel, cobalt, manganese) series and NCA (nickel, cobalt, aluminum) series with high nickel content are becoming common as cathode materials for small and medium and large-sized secondary batteries.

[0004] Generally, when it comes to cathode materials made using NCM materials, a precursor is manufactured through a co-precipitation process using nickel, cobalt, and manganese compounds as raw materials, and the precursor is mixed with a lithium compound and then heat treated to manufacture the cathode material. In particular, in order to synthesize a cathode material in the form of a single crystal, the heat treatment temperature is very high, at 850℃ or higher, so the particles are strongly bound to each other, and in order to crush these particles, a strong impact must be applied to crush them.

[0005] While this crushing process aims to separate single crystals, the problem is that single crystal particles are also broken, resulting in non-uniform particle sizes in the cathode active material. This leads to a high rate of removal of non-uniform particles during the separation process, resulting in low material yield. Furthermore, the angular surface of the particles poses a safety risk during particle filling and battery construction.

[0006] To overcome these problems, it is possible to manufacture cathode materials using a molten salt synthesis method, but in this case, a separate washing process is required to remove the salts that are added and act as catalysts, and even after the washing process, the salts are not completely removed, which ultimately causes the performance of batteries using such cathode materials to deteriorate.

[0007] Korean Patent Application No. 10-2021-0192489 lowered the sintering temperature to 820°C by manufacturing a single crystal of a cathode active material using a mixture of NaCl and LiCl as a molten salt, but this requires an additional washing process to remove the residual NaCl salt used in the mixture, and the shape of the particles is also uneven.

[0008] To solve these problems, a new method for manufacturing a cathode active material must be proposed that enables single crystal production through low-temperature calcination without catalyst injection, while also facilitating separation of the single crystal particles.

[0009] In order to solve the above problems, the inventor of the present invention separates the heat treatment processes into pre-firing and calcination steps, adds a lithium halide compound in the pre-firing process or the calcination process so that single crystals can be manufactured only by low-temperature calcination, and promotes separation between primary particles so that single crystals of the cathode active material can be simply separated after calcination without a complicated pulverization process, thereby providing a method for manufacturing a single crystal cathode material for a lithium secondary battery.

[0010] Because existing technologies have produced single-crystal cathode materials through high-temperature sintering, various crushing methods, particularly a jet mill, had to be used to crush these single crystals.

[0011] As a result, existing technologies have problems such as generating a lot of dust, having non-uniform particles of positive electrode active materials, and having an uneven particle shape, resulting in an angular shape, etc. In contrast, the method for manufacturing a single-crystal positive electrode material for a lithium secondary battery according to the present invention has a low firing temperature and allows the particles to be separated through a simple separation process after firing, so the resulting positive electrode active material has the advantage of having a smooth particle shape and a uniform particle size.

[0012] To achieve the above purpose, the cathode material used in the present invention has a Ni content of 60% or more, and is manufactured by going through a two-step heat treatment process of pre-firing and sintering, and adding a lithium halide compound during pre-firing or sintering.

[0013] A method for manufacturing a single-crystal cathode material for a lithium secondary battery according to a first aspect of the present invention comprises: (a) introducing a sodium hydroxide aqueous solution into a reactor for manufacturing a precursor of a cathode active material for a lithium secondary battery to adjust the pH of the reactor to 10 to 11.5, filling the reactor with nitrogen gas to initialize the reactor, and then continuously supplying a mixed metal aqueous solution of nickel sulfate, cobalt sulfate, and manganese sulfate and an ammonia aqueous solution into the reactor to perform a co-precipitation process, while maintaining the pH of the reactor at 10 to 11.5 by introducing the sodium hydroxide aqueous solution, setting the supply flow rate of the ammonia aqueous solution to a first value, and setting the concentration of the ammonium salt in the ammonia aqueous solution to a second value, thereby performing the co-precipitation process for 7 to 10 hours, thereby producing Ni b Co c Mn dA step of manufacturing a positive electrode active material precursor having a composition represented by the chemical formula (OH)2 (wherein, 0.6≤b≤1.0, 0.0≤c≤0.2, 0.0≤d≤0.2); (b) a step of filtering a nickel-cobalt-manganese metal composite hydroxide as a positive electrode active material precursor manufactured by coprecipitation and drying it at a temperature of 110 to 150°C for 20 to 30 hours to secure a positive electrode active material precursor before heat treatment; (c) a step of mixing zirconia oxide, aluminum oxide, and lithium fluoride with the nickel-cobalt-manganese metal composite hydroxide as a positive electrode active material precursor thus obtained to prepare first raw materials, and then placing the mixture in a container and performing solid-state mixing using zirconia balls; (d) a step of obtaining a pre-fired material by separating the solid-phase mixed first raw materials from the zirconia balls, placing them in a furnace, raising the temperature to 600 to 850°C at a first heating rate, and maintaining the temperature for 5 to 24 hours; (e) a step of preparing second raw materials by mixing lithium hydroxide in the pre-fired material, and solid-phase mixing using zirconia balls; and (f) a step of obtaining a pre-fired material by separating the second raw materials from the zirconia balls, placing them in a furnace, raising the temperature to 600 to 1000°C at a second heating rate, and maintaining the temperature for 5 to 24 hours; and 1+a Ni e Co f Mn g M1 h M2 i It is characterized by including a step of manufacturing a positive electrode active material for a lithium secondary battery having a composition represented by the chemical formula O2(0.0≤a≤1.0, 0.6≤e≤1.0, 0.0≤f≤0.2, 0.0≤g≤0.2, 0≤h≤0.05, 0≤i≤0.05).

[0014] And the method for manufacturing a single-crystal cathode material for a lithium secondary battery according to the second aspect of the present invention comprises: (a) adjusting the pH of the reactor to 10 to 11.5 by injecting a sodium hydroxide aqueous solution into a reactor for manufacturing a precursor of a cathode active material for a lithium secondary battery, and initializing the reactor by filling the reactor with nitrogen gas, and then performing a co-precipitation process by continuously supplying a mixed metal aqueous solution of nickel sulfate, cobalt sulfate, and manganese sulfate and an ammonia aqueous solution into the reactor, while maintaining the pH of the reactor at 10 to 11.5 by injecting the sodium hydroxide aqueous solution, and performing the co-precipitation process for 7 to 10 hours by setting the supply flow rate of the ammonia aqueous solution to a first value and setting the concentration of the ammonium salt in the ammonia aqueous solution to a second value, thereby producing Ni b Co c Mn dA step of manufacturing a positive electrode active material precursor having a composition represented by the chemical formula (OH)2 (wherein, 0.6≤b≤1.0, 0.0≤c≤0.2, 0.0≤d≤0.2); (b) a step of filtering a nickel-cobalt-manganese metal composite hydroxide as a positive electrode active material precursor manufactured by coprecipitation and drying it at a temperature of 110 to 150°C for 20 to 30 hours to secure a positive electrode active material precursor before heat treatment; (c) a step of mixing zirconia oxide and aluminum oxide with the nickel-cobalt-manganese metal composite hydroxide as a positive electrode active material precursor thus obtained to prepare first raw materials, and then placing the mixture in a container and performing solid-state mixing using zirconia balls; (d) a step of obtaining a pre-fired material by separating the solid-phase mixed first raw materials from the zirconia balls, placing them in a furnace, raising the temperature to 600 to 850°C at a first heating rate, and maintaining the temperature for 5 to 24 hours; (e) a step of preparing second raw materials by mixing lithium hydroxide and lithium fluoride with the pre-fired material, and solid-phase mixing using zirconia balls; and (f) a step of obtaining Li by separating the second raw materials from the zirconia balls, placing them in a furnace, raising the temperature to 600 to 1000°C at a second heating rate, and maintaining the temperature for 5 to 24 hours. 1+a Ni e Co f Mn g M1 h M2 i It is characterized by including a step of manufacturing a positive electrode active material for a lithium secondary battery having a composition represented by the chemical formula O2(0.0≤a≤1.0, 0.6≤e≤1.0, 0.0≤f≤0.2, 0.0≤g≤0.2, 0≤h≤0.05, 0≤i≤0.05).

[0015] The method for manufacturing a single crystal cathode material for a lithium secondary battery according to the present invention has the advantage of making it easy to separate the produced cathode active material particles by dividing the heat treatment into two stages of pre-firing and sintering when manufacturing the cathode material and lowering the sintering temperature by adding a lithium halide compound in the pre-firing or sintering stage.

[0016] In this way, the present invention enables the production of a cathode active material without the need for a strong pulverization operation after sintering, thereby improving the overall yield and reducing costs. In addition, the cathode active material particles have the advantage of having a uniform particle size and a smooth surface, so a lithium secondary battery produced using a cathode active material produced according to the present invention has the advantage of excellent electrochemical performance.

[0017] Moreover, the method for manufacturing a single crystal cathode material for a lithium secondary battery according to the present invention can minimize the generation of dust during the manufacturing process, and thus has the advantage of preventing environmental problems from occurring due to dust generation in production facilities.

[0018] Figure 1 is a flow chart of a method for manufacturing a single-crystal cathode material for a lithium secondary battery according to embodiments of the present invention, showing a process of synthesizing a precursor by co-precipitation and a process of synthesizing a cathode material by pre-calcination and sintering.

[0019] Figure 2 is an SEM photograph of a positive electrode active material manufactured according to Example 1 of the present invention.

[0020] Figure 3 is an SEM photograph of a positive electrode active material manufactured according to Example 2 of the present invention.

[0021] Figure 4 is an SEM photograph of a positive electrode active material manufactured according to Comparative Example 1.

[0022] Figure 5 is an SEM photograph of a positive electrode active material manufactured according to Comparative Example 2.

[0023] Figure 6 is a table summarizing the results of measuring residual lithium of each positive electrode active material manufactured according to Example 1, Example 2, and Comparative Example 1 of the present invention.

[0024] Figure 7 shows the capacity curves of each half-cell manufactured using the positive electrode active material manufactured according to Examples 1 and 2 of the present invention and Comparative Example 1.

[0025] The method for manufacturing a cathode material for a lithium secondary battery according to the first aspect of the present invention will be described in its entirety.

[0026] (a) Ni by co-precipitation process b Co c Mn d A step of manufacturing a positive electrode active material precursor having a composition represented by the chemical formula (OH)2 (wherein, 0.6≤b≤1.0, 0.0≤c≤0.2, 0.0≤d≤0.2);

[0027] (b) a step of mixing nickel-cobalt-manganese metal composite hydroxide as a cathode active material precursor manufactured by co-precipitation, a lithium halide compound, and first metal additive (M1) raw materials, and then putting the mixture into a kiln, heating it to a temperature of 650 to 850°C, and then performing a pre-firing operation for 2 to 10 hours; and

[0028] (c) Lithium salt and a second metal additive (M2) are mixed with the above-mentioned pre-calcined material, and the mixture is calcined at a temperature of 650 to 900°C for 5 to 24 hours to produce Li 1+a Ni e Co f Mn g M1 h M2 i A step of manufacturing a positive electrode active material for a lithium secondary battery having a composition represented by the chemical formula O2(0.0≤a≤1.0, 0.6≤e≤1.0, 0.0≤f≤0.2, 0.0≤g≤0.2, 0≤h≤0.05, 0≤i≤0.05); is included.

[0029] Meanwhile, the method for manufacturing a cathode material for a lithium secondary battery according to the second aspect of the present invention will be described in its entirety.

[0030] (a) Ni by co-precipitation process b Co c Mn d A step of manufacturing a positive electrode active material precursor having a composition represented by the chemical formula (OH)2 (wherein, 0.6≤b≤1.0, 0.0≤c≤0.2, 0.0≤d≤0.2);

[0031] (b) a step of mixing nickel-cobalt-manganese metal composite hydroxide as a cathode active material precursor manufactured by co-precipitation and the first metal additive (M1) raw materials, then putting the mixture into a kiln and performing a pre-firing operation at a temperature of 650 to 850°C for 5 to 24 hours; and

[0032] (c) Lithium salt, lithium halide compound and second metal additive (M2) are mixed with the above-mentioned pre-calcined material, and the mixture is calcined at a temperature of 650 to 900°C for 5 to 24 hours to obtain Li 1+a Ni e Co f Mn g M1 h M2 i A step of manufacturing a positive electrode active material for a lithium secondary battery having a composition represented by the chemical formula O2(0.0≤a≤1.0, 0.6≤e≤1.0, 0.0≤f≤0.2, 0.0≤g≤0.2, 0≤h≤0.05, 0≤i≤0.05); is included.

[0033] The above first metal additive (M1) is one element or a plurality of elements selected from the group consisting of Mo, Nb, Ta, W, Zr, etc., and the amount of the first metal additive (M1) is preferably set to 0≤M1≤0.1, and more specifically, 0.01≤M1≤0.05.

[0034] And the above second metal additive (M2) is one element or a plurality of elements selected from the group consisting of Al, B, Ba, Ce, Cr, Fe, Mg, Sb, Ti, W, Zr, etc., and the amount of the second metal additive (M2) is preferably set to 0≤M2≤0.1, and more specifically, 0.01≤M2≤0.05.

[0035] The above lithium halide compounds include LiF, LiCl, LiBr, LiI, etc., and LiF and LiCl are particularly effective. The amount of lithium halide compound added during pre-firing or sintering is 0.01≤lithium halide compound≤0.2. When it is less than 0.01, the effect of lowering the sintering temperature is not significant, and when it is 0.2 or more, the size of the single crystal particles may become small.

[0036] The method for manufacturing a single crystal cathode material for a lithium secondary battery according to the present invention is described in detail with detailed embodiments and comparative examples as follows.

[0037] <Example 1>

[0038] A 5 L reactor was charged with a sodium hydroxide aqueous solution to adjust the pH inside the reactor to 11.0, then nitrogen gas was blown in at a flow rate of 1 L / min, the reactor temperature was initialized to 50°C, and the stirring speed was 1000 RPM. A 2 M metal aqueous solution in which nickel sulfate, cobalt sulfate, and manganese sulfate were mixed in a molar ratio of 92:5:2 was continuously charged into the reactor at 0.16 L / hr, and a 10 M ammonia aqueous solution was continuously charged into the reactor at 0.032 L / hr. A 2 M sodium hydroxide aqueous solution was then charged to adjust the pH inside the reactor to 11. At this time, the average residence time of the solution inside the reactor was 8 hours, and spherical nickel-cobalt-manganese composite hydroxides were continuously obtained (co-precipitation step).

[0039] The nickel-cobalt-manganese composite hydroxide thus obtained was filtered and dried at 130°C for 24 hours to be used as a precursor before heat treatment.

[0040] Next, the precursor before heat treatment and zirconia oxide (ZrO2), aluminum oxide (Al2O3), and lithium fluoride (LiF) were placed in a high-density polyethylene (HDPE) bottle at a molar ratio of 0.983:0.005:0.01:0.05, and zirconia balls were placed so that the ratio of zirconia balls to the input raw materials was 5:1, and then solid-state mixing was performed at 100 rpm for 1 hour using a ball miller.

[0041] After separating the solid mixed raw materials from the zirconia balls, they were placed in a heating furnace and heated to 820℃ at a heating rate of 1.25℃ / min, and then maintained for 10 hours to produce a pre-fired material ('pre-fired process' completed).

[0042] The above-mentioned pre-calcined material and lithium hydroxide (LiOH·H2O) were placed in a high-density polyethylene (HDPE) bottle at a molar ratio of 1.0:0.97, and zirconia balls were added so that the ratio of zirconia balls to the input raw material was 5:1, and then solid-phase mixing was performed at 100 rpm for 1 hour using a ball miller.

[0043] After separating the solid mixed raw materials from the zirconia balls, they were placed in a heating furnace and heated to 820℃ at a heating rate of 1.25℃ / min, and then maintained for 10 hours to carry out a sintering process, thereby manufacturing a cathode active material ('sintering process' completed).

[0044] The final cathode active material was manufactured by crushing the cathode active material produced by the sintering process with a plastic mortar. The SEM image of the cathode active material thus manufactured is shown in Fig. 2.

[0045]

[0046] <Example 2>

[0047] A 5 L reactor was charged with a sodium hydroxide aqueous solution to adjust the pH inside the reactor to 11.0, then nitrogen gas was blown in at a flow rate of 1 L / min, the reactor temperature was initialized to 50°C, and the stirring speed was 1000 RPM. A 2 M metal aqueous solution in which nickel sulfate, cobalt sulfate, and manganese sulfate were mixed in a molar ratio of 92:5:2 was continuously charged into the reactor at 0.16 L / hr, and a 10 M ammonia aqueous solution was continuously charged into the reactor at 0.032 L / hr. A 2 M sodium hydroxide aqueous solution was then charged to adjust the pH inside the reactor to 11. At this time, the average residence time of the solution inside the reactor was 8 hours, and spherical nickel-cobalt-manganese composite hydroxides were continuously obtained (co-precipitation step).

[0048] The nickel-cobalt-manganese composite hydroxide thus obtained was filtered and dried at 130°C for 24 hours and used as a precursor before heat treatment.

[0049] Next, the precursor before heat treatment and zirconia oxide (ZrO2) and aluminum oxide (Al2O3) were placed in a high-density polyethylene (HDPE) bottle at a molar ratio of 0.983:0.005:0.01, and zirconia balls were placed so that the ratio of zirconia balls to the input raw materials was 5:1, and then solid-state mixing was performed at 100 rpm for 1 hour using a ball miller.

[0050] After separating the solid mixed raw materials from the zirconia balls, they were placed in a heating furnace and heated to 820℃ at a heating rate of 1.25℃ / min, and then maintained for 10 hours to produce a pre-fired material ('pre-fired process' completed).

[0051] The above-mentioned pre-calcined material and lithium hydroxide (LiOH·H2O) and lithium fluoride (LiF) were placed in a high-density polyethylene (HDPE) bottle at a molar ratio of 1.0:0.97:0.05, and zirconia balls were added so that the ratio of zirconia balls to the input raw materials was 5:1, and then solid-state mixing was performed at 100 rpm for 1 hour using a ball miller.

[0052] After separating the solid mixed raw materials from the zirconia balls, they were placed in a heating furnace and heated to 820℃ at a heating rate of 1.25℃ / min, and then maintained for 10 hours to carry out a sintering process, thereby manufacturing a cathode active material ('sintering process' completed).

[0053] The final cathode active material was manufactured by crushing the cathode active material produced by the sintering process with plastic mortar, and the SEM image of the cathode active material thus manufactured is as shown in Fig. 3.

[0054]

[0055] <Comparative Example 1>

[0056] Compared to Example 1, it differs in that only the firing process is performed directly without going through the pre-firing process.

[0057] The precipitated positive electrode active material precursor was mixed with lithium hydroxide (LiOH·H2O), zirconia oxide (ZrO2), and aluminum oxide (Al2O3) through the same process as the precipitation process of Example 1, and the molar ratios were 0.985:1.02:0.005:0.01, respectively, and placed in a high-density polyethylene (HDPE) bottle. Zirconia balls were placed so that the ratio of zirconia balls to the input raw materials was 5:1, and then solid-state mixing was performed at 100 rpm for 1 hour using a ball miller.

[0058] After separating the solid-phase mixed raw materials from the zirconia balls, they were placed in a furnace and heated to 880°C at a heating rate of 1.25°C / min, and maintained for 10 hours to produce a cathode active material. The cathode active material thus produced was then pulverized using agate mortar. The SEM image of the cathode active material after pulverization is shown in Fig. 4.

[0059]

[0060] Comparative Example 2

[0061] Compared to Example 2, it differs in that only the firing process is performed directly without going through the pre-firing process.

[0062] The precipitated positive electrode active material precursor was mixed with lithium hydroxide (LiOH·H2O), zirconia oxide (ZrO2), aluminum oxide (Al2O3), and lithium fluoride (LiF) through the same process as the precipitation process of Example 2, and the molar ratios of each were 0.985:0.97:0.005:0.01:0.05, and placed in a high-density polyethylene (HDPE) bottle. Zirconia balls were placed so that the ratio of zirconia balls to the input raw materials was 5:1, and then solid-state mixing was performed at 100 rpm for 1 hour using a ball miller.

[0063] After separating the solid-phase mixed raw materials from the zirconia balls, they were placed in a furnace and heated to 820°C at a heating rate of 1.25°C / min, and maintained for 10 hours to produce a cathode active material. The cathode active material thus produced was pulverized using an arc mortar. The SEM image of the cathode active material after pulverization is shown in Fig. 5.

[0064]

[0065] The residual lithium of the positive electrode active materials manufactured according to the above Examples 1, 2, and Comparative Example 1 was measured, and the results were presented in the table in Fig. 6.

[0066] To measure residual lithium, 5 g of the cathode active material was immersed in 100 g of ultrapure water, stirred for 15 minutes, and the filtrate was titrated with 0.1 N HCl. The volume of HCl added until the pH of the filtrate became 5 was measured to analyze the residual lithium in the cathode active material.

[0067] As can be seen in the table in Fig. 6, the amount of residual lithium in the positive electrode active material was greatly reduced in Examples 1 and 2 compared to Comparative Example 1, and it can be seen that the residual lithium was particularly greatly reduced in Example 2.

[0068] Meanwhile, the evaluation of electrochemical characteristics to compare the discharge capacity of the positive electrode active materials of Examples 1 and 2 and Comparative Example 1 was conducted in the following manner.

[0069] ① The positive electrode material manufactured in the above examples and comparative example 1 was used as a positive electrode active material, and (positive electrode active material): (conductive agent): (polyvinyl fluoride binder) was dissolved in an N-methylpyrrolidone solvent at a weight ratio of 90:5:5 to manufacture a positive electrode active material slurry.

[0070] ② The above cathode active material slurry was coated to a thickness of 40 μm on a 20 μm thick aluminum foil, and then cut into a square shape of 1.9 x 1.9 cm2 to manufacture an electrode.

[0071] ③ A pouch-type half-cell was manufactured in a glove box using the above-mentioned positive electrode and lithium metal as the counter electrode. At this time, a mixed solution (1:1 volume ratio) of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) containing 1M LiPF6 dissolved therein was used as the electrolyte.

[0072] ④ The assembled half-cells were tested at 25°C under 0.1C / 0.1C charge / discharge conditions for capacity measurement. At this time, the voltage range in which charge / discharge occurred was 2.7 to 4.3 V.

[0073] Figure 7 is a discharge capacity graph showing the discharge capacity values ​​of Example 1, Example 2, and Comparative Example 1. Referring to Figure 7, the discharge capacities of the batteries in Example 1 and Example 2 were 216 mAh and 208 mAh, respectively, and the discharge capacity of the battery in Comparative Example 1 was 202 mAh.

[0074] The method for manufacturing a single crystal cathode material for a lithium secondary battery according to the present invention has the advantage of making it easy to separate the produced cathode active material particles by dividing the heat treatment into two stages of pre-firing and sintering when manufacturing the cathode material and lowering the sintering temperature by adding a lithium halide compound in the pre-firing or sintering stage.

[0075] In this way, the present invention enables the production of a cathode active material without the need for a strong pulverization operation after sintering, thereby improving the overall yield and reducing costs. In addition, the cathode active material particles have the advantage of having a uniform particle size and a smooth surface, so a lithium secondary battery produced using a cathode active material produced according to the present invention has the advantage of excellent electrochemical performance.

[0076] Moreover, the method for manufacturing a single crystal cathode material for a lithium secondary battery according to the present invention can minimize the generation of dust during the manufacturing process, and thus has the advantage of preventing environmental problems from occurring due to dust generation in production facilities.

[0077] 100: Co-precipitation stage

[0078] 200: Pre-firing stage

[0079] 300: Firing stage

Claims

1.(a) In a reactor for manufacturing a precursor of a cathode active material for a lithium secondary battery, a sodium hydroxide aqueous solution is introduced to adjust the pH of the reactor to 10 to 11.5, and the reactor is filled with nitrogen gas to initialize the reactor, and a metal aqueous solution containing a mixture of nickel sulfate, cobalt sulfate, and manganese sulfate and an ammonia aqueous solution are continuously supplied into the reactor to carry out a co-precipitation process, while maintaining the pH of the reactor at 10 to 11.5 by introducing the sodium hydroxide aqueous solution, and while setting the supply flow rate of the ammonia aqueous solution to a first value and setting the concentration of the ammonium salt in the ammonia aqueous solution to a second value, the co-precipitation process is carried out for 7 to 10 hours, thereby producing Ni b Co c Mn d A step of manufacturing a positive electrode active material precursor having a composition represented by the chemical formula (OH)2 (wherein, 0.6≤b≤1.0, 0.0≤c≤0.2, 0.0≤d≤0.2); (b) A step of filtering the nickel-cobalt-manganese metal composite hydroxide as a cathode active material precursor manufactured by co-precipitation and drying it at a temperature of 110 to 150°C for 20 to 30 hours to secure a cathode active material precursor before heat treatment; (c) a step of mixing zirconia oxide, aluminum oxide, and lithium fluoride with the nickel-cobalt-manganese metal composite hydroxide as the positive electrode active material precursor obtained above to prepare first raw materials, then placing the mixture in a container and performing solid-state mixing using zirconia balls; (d) A step of obtaining a pre-fired material by separating the solid-phase mixed first raw materials from the zirconia balls, placing them in a heating furnace, increasing the temperature to 600 to 850°C at the first heating rate, and then maintaining the temperature for 5 to 24 hours; (e) a step of mixing lithium hydroxide into the above-mentioned pre-calcined material and then using zirconia balls to solidify and produce second raw materials; and (f) After separating the above second raw materials from the zirconia balls, place them in a furnace and raise the temperature to 600 to 1000°C at the second heating rate, and then maintain it for 5 to 24 hours to sinter them, thereby obtaining Li 1+a Ni e Co f Mn g M1 h M2 i A method for producing a single-crystal cathode material for a lithium secondary battery, characterized by comprising the step of producing a cathode active material for a lithium secondary battery having a composition represented by the chemical formula O2(0.0≤a≤1.0, 0.6≤e≤1.0, 0.0≤f≤0.2, 0.0≤g≤0.2, 0≤h≤0.05, 0≤i≤0.05). 2.(a) In order to manufacture a precursor of a cathode active material for a lithium secondary battery, a sodium hydroxide aqueous solution is injected into a reactor to adjust the pH of the reactor to 10 to 11.5, and the reactor is filled with nitrogen gas to initialize the reactor, and a metal aqueous solution containing nickel sulfate, cobalt sulfate, and manganese sulfate and an ammonia aqueous solution are continuously supplied into the reactor to carry out a co-precipitation process, while maintaining the pH of the reactor at 10 to 11.5 by the injection of the sodium hydroxide aqueous solution, and while setting the supply flow rate of the ammonia aqueous solution to a first value and setting the concentration of the ammonium salt in the ammonia aqueous solution to a second value, the co-precipitation process is carried out for 7 to 10 hours, thereby producing Ni b Co c Mn d A step of manufacturing a positive electrode active material precursor having a composition represented by the chemical formula (OH)2 (wherein, 0.6≤b≤1.0, 0.0≤c≤0.2, 0.0≤d≤0.2); (b) A step of filtering the nickel-cobalt-manganese metal composite hydroxide as a cathode active material precursor manufactured by co-precipitation and drying it at a temperature of 110 to 150°C for 20 to 30 hours to secure a cathode active material precursor before heat treatment; (c) a step of mixing zirconia oxide and aluminum oxide with the nickel-cobalt-manganese metal composite hydroxide as the positive electrode active material precursor obtained above to prepare first raw materials, then placing the mixture in a container and performing solid-state mixing using zirconia balls; (d) A step of obtaining a pre-fired material by separating the solid-phase mixed first raw materials from the zirconia balls, placing them in a heating furnace, increasing the temperature to 600 to 850°C at the first heating rate, and then maintaining the temperature for 5 to 24 hours; (e) a step of mixing lithium hydroxide and lithium fluoride into the above-mentioned pre-calcined material and then using zirconia balls to solid-state mix the mixture to produce second raw materials; and (f) After separating the above second raw materials from the zirconia balls, place them in a furnace and raise the temperature to 600 to 1000°C at the second heating rate, and then maintain it for 5 to 24 hours to sinter them, thereby obtaining Li 1+a Ni e Co f Mn g M1 h M2 i A method for producing a single-crystal cathode material for a lithium secondary battery, characterized by comprising the step of producing a cathode active material for a lithium secondary battery having a composition represented by the chemical formula O2(0.0≤a≤1.0, 0.6≤e≤1.0, 0.0≤f≤0.2, 0.0≤g≤0.2, 0≤h≤0.05, 0≤i≤0.05).

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