Manufacturing method of Ni-Co-Mn composite precursor with enhanced life characteristics using waterborne coating

Abstract

The present invention relates to a method for manufacturing an NCM-based composite precursor, and in particular, to a method for manufacturing a nickel-cobalt-manganese composite precursor with improved lifespan characteristics through a water-based coating of heterogeneous elements.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing an NCM-based composite precursor (Ni-Co-Mn-based composite precursor) used in lithium secondary batteries, and in particular, to a technology for aqueous coating of heterogeneous elements to improve the physical properties of the NCM-based composite precursor. Background Technology

[0003] Conventional high-content (80% or more) nickel NCM-based composite precursors are used to improve output characteristics and high-temperature lifespan as lithium-ion batteries; however, high-content nickel NCM-based composite precursors have the disadvantage of reduced stability due to the presence of lithium.

[0005] Lithium secondary batteries using high-content nickel NCM-based composite precursors have the problem that while battery capacity increases (capacity increases by 2Ah per kg of material for every 1% increase in nickel content), the degradation of battery characteristics due to charging and discharging becomes more severe. The degradation problem in nickel secondary batteries using high-content nickel NCM-based composite precursors is known to be caused by nickel leaching due to the reaction between the cathode and the electrolyte and the generation of hydrofluoric acid (HF) in the electrolyte, which particularly leads to a deterioration in high-temperature lifespan characteristics. Furthermore, in high-nickel compositions, structural and chemical stability is reduced, and the deterioration of thermal stability of the cathode at high temperatures is pointed out as a serious problem.

[0007] Due to degradation and stability issues, recent attempts have been made to improve physical properties such as thermal stability, capacity, and cycle life by partially substituting heterogeneous elements into nickel-cobalt-manganese cathode active material precursors or coating their surfaces with heterogeneous elements.

[0009] Conventional non-aqueous coating methods for composite precursors for lithium secondary batteries generally involve coating through a surface treatment process after drying a mixed solution or obtaining a composite precursor through a high-temperature evaporation process (immersion of volatile organic compounds → stirring → high-temperature evaporation → subsequent process). However, these methods have problems such as complex processes and environmental pollution caused by the volatilization of harmful organic compounds.

[0011] The inventors derived the present invention as a result of researching a water-based coating method that overcomes the disadvantages of the above-mentioned non-water-based coating method. Prior art literature

[0013] Korean Patent Publication No. 10-2019-0021070 The problem to be solved

[0014] The present invention aims to manufacture an NCM-based composite precursor with improved productivity and physical properties by developing a coating technology with long-term stable lifespan characteristics for a high-nickel NCM-based composite precursor for lithium secondary batteries and simplifying the process.

[0016] In addition, the present invention aims to provide a technology capable of stably manufacturing NCM-based composite precursors of uniform size and physical properties by measuring pH in real time during the co-precipitation process and sending a warning to the experimenter when the pH deviates from an acceptable range. means of solving the problem

[0018] To achieve the above objective, the present invention provides an NCM-based precursor (Ni x Co y Mn 1-x-y (OH)2) provides a method to improve lifespan characteristics through a water-based coating method of heterogeneous elements (M = Si, Al, Ti, Sn, etc.).

[0020] In particular, the present invention comprises a step (1) of preparing a co-precipitation solution containing Ni, Co and Mn for manufacturing an NCM-based composite precursor; a step (20) of preparing an aqueous solution of heterogeneous elements (M = Si, Al, Ti, Sn, etc.); a step (3) of mixing and introducing the co-precipitation solution and the aqueous solution of heterogeneous elements from steps (1) and (2) into a co-precipitation reactor, and simultaneously performing co-precipitation and heterogeneous element coating of the NCM-based composite precursor while adjusting the pH; and a step (4) of proceeding with a subsequent process of the NCM-based composite precursor coated with heterogeneous metal from step (3).

[0022] In particular, it is preferable that the above heterogeneous element consists of nano-sized heterogeneous element microparticles dispersed in an aqueous solution.

[0024] In particular, in step (3) above, the pH can be measured in real time.

[0026] In particular, in the above step (3), an alarm can be activated if the real-time measurement of pH exceeds the error range.

[0028] In particular, in step (3) above, the aqueous solution of the heterogeneous element can be supplied to the co-precipitation solution by the atomization method.

[0030] In particular, the subsequent process of the above step (4) may include a washing step and a drying step. Effects of the invention

[0032] When a composite precursor is coated through the coating technology and process simplification of the present invention, heterogeneous elements are uniformly coated on the surface of a high-nickel composite precursor, thereby enabling the manufacture of a composite precursor with a simplified process, unlike conventional coating technologies.

[0034] The coating technology and process simplification of the present invention can be utilized more effectively in terms of production efficiency during mass-scale manufacturing processes. Furthermore, the water-based coating process of the present invention not only simplifies the process by not using volatile organic compounds (ETH) and omitting the high-temperature evaporation step, but also enables the synthesis of a uniform coating through the atomization method (coating solution spraying → stirring / coating → subsequent process). Brief explanation of the drawing

[0036] FIG. 1 is a schematic diagram illustrating the method of the present invention. Figure 2 is an alarm monitoring screen based on real-time measurement of pH during the co-precipitation process of step (3) in the present invention. Figure 3 is an SEM measurement image of an NCM-based precursor prepared by a comparative example, and Figure 4 is an SEM measurement image of an NCM-based precursor prepared by an example. Figure 5 shows the high temperature (60°C) lifespan evaluation analysis results of the coin cells of the example and comparative example (red: example, black: comparative example), and Figure 6 shows the thermal stability evaluation results of the example and comparative example. Figures 7 and 8 are particle size distributions of composite precursors prepared by comparative example and example, respectively. Specific details for implementing the invention

[0037] FIG. 1 is a schematic diagram illustrating the method of the present invention.

[0039] The present invention comprises a stirring and co-precipitation step (1) of an aqueous solution of raw materials for manufacturing an NCM-based composite precursor; a step (2) of adding and stirring an aqueous solution containing a heterogeneous element (M = Si, Al, Ti, Sn, etc.) after the reaction of step (1) is completed; a step (3) of continuous pH control and alarm monitoring by adding the aqueous solution of the heterogeneous element during the additional stirring step of step (2); and a step (4) of carrying out a subsequent process of washing and drying the NCM-based composite precursor coated with a heterogeneous metal of step (3).

[0041] A nickel-cobalt-manganese composite precursor can be manufactured using a simplified aqueous coating process compared to the conventional aqueous coating process presented in this invention, utilizing a technology and process that does not use organic compounds, omits the high-temperature evaporation step, and employs an atomization method. In the following experiments, supplying an aqueous solution of a heterogeneous element to an aqueous solution of an NCM-based raw material using a nitrogen gas atomization method increases the solubility of the heterogeneous element within the NCM-based aqueous solution and increases the coating efficiency for the NCM-based composite precursor. In this invention, an aqueous solution of a heterogeneous element was supplied to an NCM-based aqueous solution using nitrogen gas and a nozzle atomization method.

[0043] FIG. 2 is an alarm monitoring screen based on real-time measurement of pH during the co-precipitation process of step (3) in the present invention. When the set value, for example, pH 11, is exceeded within a certain range during co-precipitation, an alarm is triggered, and accordingly, the dosage of the pH regulator is adjusted to quickly bring the pH to the set value. In addition, if the alarm sounds, all reactants in the reactor may be discarded.

[0045] Examples

[0047] Based on 2L of ultrapure water, nickel sulfate, cobalt sulfate, and manganese sulfate at concentrations of 2.0–2.5 molar and 0.8 x :0.1 y :0.1 1-x-y A metal aqueous solution was prepared with a molar ratio of .

[0049] In addition, aqueous solutions of heterogeneous elements (M= Si, Al, Ti, Sn, etc.) were prepared at a molar concentration of 0.1 to 0.5 based on 2 L of ultrapure water.

[0051] 3L of Ultrapure water was filled into a double-jacketed water tank reactor, and the temperature was maintained at 50–60°C using a constant temperature water bath device. A quantitative amount of basic aqueous solutions of NaOH and NH4OH (4–7 ml / min) was added to the reactor, and a mixture of a pre-prepared aqueous metal solution (6 ml / min), an aqueous solution of a heterogeneous metal (6 ml / min), and N2 gas (3 L / min) was added. The aqueous solution of the heterogeneous metal was supplied to the reactor via an atomization method using N2 gas (see Fig. 1). In addition, the solution stirring speed was set and maintained at 800–900 RPM.

[0053] The titanium-containing nickel-cobalt-manganese composite precursor prepared through the above process was precipitated for 12 to 24 hours and then recovered. The recovered precursor was washed several times using a vacuum filtration process with ultrapure water and an aqueous NaOH solution with a concentration of 0.1 to 0.5 molar, and then dried in a furnace at 120°C. Finally, a nickel-cobalt-manganese composite precursor in powder form was obtained.

[0055] Comparative example

[0057] A nickel-cobalt-manganese composite precursor manufactured using a conventional synthesis process, utilizing nickel sulfate, cobalt sulfate, and manganese sulfate as raw materials, with a molar concentration of 2.0–2.5 and 0.8 based on 2L of ultrapure water x :0.1 y :0.1 1-x-y A metal aqueous solution was prepared at a molar ratio. 3 L of ultrapure water was filled into a standard reactor equipped with baffles and a stirrer, and the temperature was maintained at 50–60°C using a constant temperature water bath device, while the solution stirring speed was set and maintained at 800–900 RPM. A quantitative amount of basic aqueous solutions of NaOH and NH4OH (4–7 ml / min) was introduced into the reactor via a pump, and a mixture of the pre-prepared metal aqueous solution (6 ml / min) and N2 gas (3 L / min) was introduced. After the reaction was completed, the precipitated nickel-cobalt-manganese composite precursor was recovered, washed several times with ultrapure water and an aqueous NaOH solution with a concentration of 0.1–0.5 molar using a vacuum filter, and then dried using a furnace at 120°C to obtain a nickel-cobalt-manganese composite precursor in powder form.

[0059] Experimental Example 1: SEM Measurement

[0061] Figure 3 is an SEM measurement image of an NCM-based precursor prepared by a comparative example, and Figure 4 is an SEM measurement image of an NCM-based precursor prepared by an example. It can be seen from the SEM surface analysis data of the example and the comparative example that there is no difference, and through this, it was confirmed that the method of the present invention is applicable in the process.

[0063] Experimental Example 2: High-temperature life evaluation (60℃) of a Coin-Cell with a heterogeneous element coating composite precursor

[0065] Figure 5 shows the high temperature (60°C) lifespan evaluation analysis results of the coin cells of the example and comparative example (red: example, black: comparative example), and Figure 6 shows the thermal stability evaluation results of the example and comparative example.

[0067] As shown in the high-temperature life evaluation analysis results of Fig. 5, it was found that the high-temperature characteristics of the coin cell with the NCM-based composite precursor according to the embodiment of the present invention are superior to those of the comparative example.

[0069] As shown in the thermal stability evaluation of Figure 6, a peak is observed at a higher temperature in the example compared to the comparative example, which means that the sample of the example has superior thermal stability compared to the comparative example.

[0071] Experimental Example 3: Particle Size Analysis Evaluation of Heterogeneous Element Coating Composite Precursor Application

[0073] Figures 7 and 8 are particle size distributions of composite precursors prepared by comparative example and example, respectively.

[0075] Referring to Figures 7 and 8, it can be seen that there is a slight difference in the particle size distribution between the example and the comparative example. This difference is interpreted as being due to the fact that in the example, the reactivity of the metal salt is improved by changing the process conditions, and precursors of 4 μm or smaller are eliminated.

Claims

Claim 1 A method for manufacturing a nickel-cobalt-manganese composite precursor with improved lifespan characteristics through water-based coating, comprising: a step (1) of preparing a co-precipitation solution containing Ni, Co and Mn for manufacturing an NCM-based composite precursor; a step (2) of preparing a heterogeneous element aqueous solution in which nano-sized heterogeneous element microparticles are dispersed in an aqueous solution; a step (3) of mixing and introducing the co-precipitation solution and the heterogeneous element aqueous solution of steps (1) and (2) into a co-precipitation reactor, and simultaneously performing co-precipitation and heterogeneous element coating of the NCM-based composite precursor while adjusting the pH; and a step (4) of proceeding with a subsequent process of the NCM-based composite precursor coated with heterogeneous metal of step (3), wherein in step (3), the pH is measured in real time, and an alarm is activated if the real-time measurement of the pH exceeds the error range. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 A method for manufacturing a nickel-cobalt-manganese composite precursor with improved lifespan characteristics through an aqueous coating, wherein in step (3) above, the aqueous solution of a heterogeneous element is supplied to an NCM co-precipitation solution by an atomization method. Claim 6 A method for manufacturing a nickel-cobalt-manganese composite precursor with improved lifespan characteristics through water-based coating, wherein the subsequent process of step (4) includes a washing step and a drying step in claim 1. Claim 7 A method for manufacturing a nickel-cobalt-manganese composite precursor with improved lifespan characteristics through a water-based coating, wherein, in claim 1, the heterogeneous element is any one selected from Si, Al, Ti, and Sn.

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