Method for regenerating waste precursor for cathode material of lithium secondary battery

Abstract

The present invention relates to a method for regenerating a waste precursor for a cathode material of a lithium secondary battery, the method comprising: a first step of preparing a waste precursor solution including a waste precursor sulfate produced by mixing a waste precursor (NCM(OH)2) for a cathode active material including Ni, Co, and Mn with an aqueous leaching solution containing sulfuric acid and a reducing agent; a second step of preparing a transition metal solution including a transition metal sulfate produced by mixing nickel sulfate, cobalt sulfate, and manganese sulfate with water; a third step of preparing a mixed precursor solution by mixing 2.5-4 parts by weight of a transition metal solution with respect to 1 part by weight of the waste precursor solution; a fourth step of introducing an aqueous ammonia solution as a complexing agent into a reactor containing distilled water, and injecting nitrogen gas into the reactor; and a fifth step of supplying the mixed precursor solution and NaOH as a precipitant into the reactor, and precipitating a precursor for a cathode active material by supplying the NaOH at a ratio of 1.8-2.3 moles with respect to 1 mole of the total of the waste precursor sulfate and the transition metal sulfate contained in the mixed precursor solution.

Description

Method for regenerating waste precursors for lithium secondary battery cathode materials

[0001] The present invention relates to a method for regenerating a waste precursor for a lithium secondary battery cathode material, which can improve the efficiency of regeneration of the waste precursor without generating additional waste precursors during the regeneration process of the waste precursor, and can recycle the solution used for regeneration, thereby improving process efficiency.

[0002] With the increasing development and demand for small electronic devices such as smartphones, smartwatches, tablet PCs, and digital cameras, as well as electric vehicles such as electric cars and electric bicycles, demand for lithium secondary batteries, the energy source used in these devices, is also skyrocketing. Lithium secondary batteries consist of a cathode and an anode, an electrolyte that acts as a conduit for ions, and a separator that separates them. Lithium secondary batteries currently dominate the secondary battery market due to their advantages, including high energy density, long cycle life, and low self-discharge.

[0003] Among the components of lithium secondary batteries, cathode materials contain expensive useful metals such as nickel, manganese, and cobalt. Due to problems such as declining reserves due to continuous mining and supply and demand instability due to rapid demand, various attempts are being made to extract and recycle these metals from waste lithium secondary batteries or waste precursors produced during the cathode material manufacturing process.

[0004] As a method of regenerating lithium from spent precursors, a method of adding hydrogen peroxide to the resulting leachate after acid leaching the spent precursors with an acid solution such as sulfuric acid, hydrochloric acid, or phosphoric acid to regenerate lithium ions has been proposed. However, there was a problem in that metal oxides were formed due to the oxygen generated from the hydrogen peroxide, which changed the composition of the precursor and caused it to be classified as a spent precursor again.

[0005] Accordingly, it is necessary to develop a new waste precursor regeneration technology that can improve regeneration efficiency and quality without regenerating waste precursors in the process of regenerating lithium from waste precursors.

[0006] The present invention provides a method for regenerating a waste precursor for a lithium secondary battery cathode material, which can improve the efficiency of the process by improving the regeneration efficiency of the waste precursor without generating additional waste precursors during the regeneration process of the waste precursor and recycling the solution used for regeneration.

[0007] In order to achieve the above-described object, one embodiment of the present invention comprises the steps of: a first step of preparing a spent precursor solution containing spent precursor sulfate produced by mixing a spent precursor (NCM(OH)2) for a cathode active material containing Ni, Co, and Mn with a leaching solution containing sulfuric acid and a reducing agent; a second step of preparing a transition metal solution containing transition metal sulfate produced by mixing nickel sulfate, cobalt sulfate, and manganese sulfate in water; a third step of preparing a mixed precursor solution by mixing 2.5 to 4 parts by weight of a transition metal solution with 1 part by weight of a spent precursor solution; a fourth step of introducing an aqueous ammonia solution as a complexing agent into a reactor containing distilled water and injecting nitrogen gas; And a fifth step of supplying a mixed precursor solution and a precipitant, NaOH, to the reactor, at a ratio of 1.8 to 2.3 moles of NaOH based on 1 mole of a mixture of spent precursor sulfate and transition metal sulfate contained in the mixed precursor solution, thereby precipitating a precursor for a positive electrode active material; relates to a method for regenerating a spent precursor for a positive electrode material of a lithium secondary battery, comprising:

[0008] The solid-liquid ratio of the waste precursor solution manufactured in the first step, as defined by the following [Formula 1], may be 0.067 to 0.125.

[0009] [Formula 1]

[0010] The reducing agent may be formic acid.

[0011] In the first step, when preparing the spent precursor solution, the molar ratio of the mixed spent precursor, sulfuric acid, and reducing agent may be 1:0.9 to 1.1:0.3 to 3.8.

[0012] The above first step can be performed at a temperature range of 60 to 80 °C.

[0013] When removing the supernatant of the reaction solution containing the precursor precipitate for the positive electrode active material obtained through the above 5th step and further adding the mixed precursor solution, the ammonia aqueous solution as a complexing agent, and NaOH to grow the precursor precipitate for the positive electrode active material is defined as one step, the step may be performed once or repeated two or more times.

[0014] The method for regenerating a waste precursor for a lithium secondary battery cathode material of the present invention improves the regeneration efficiency of the waste precursor without generating additional waste precursors during the regeneration process, and can recycle the solution used for regeneration, thereby improving process efficiency and production quality.

[0015] Before describing in detail the preferred embodiments of the present invention below, it should be noted that the terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that are consistent with the technical spirit of the present invention.

[0016] Throughout this specification, whenever a part is said to “include” a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise stated.

[0017] Throughout this specification, “%” used to indicate the concentration of a specific substance means (weight / weight)% for solid / solid, (weight / volume)% for solid / liquid, and (volume / volume)% for liquid / liquid, unless otherwise stated.

[0018] The identifiers used in each step are for convenience of explanation and do not indicate the order of the steps. The steps may be performed in a different order than stated, unless the context clearly dictates otherwise. In other words, the steps may be performed in the same order as stated, substantially simultaneously, or in the opposite order.

[0019] The present invention will be described in detail with reference to embodiments and drawings. These embodiments are provided solely as examples to more specifically illustrate the present invention, and it will be apparent to those skilled in the art that the scope of the present invention is not limited by these embodiments.

[0020] Hereinafter, embodiments of the present invention will be described. However, the scope of the present invention is not limited to the following preferred embodiments, and those skilled in the art can implement various modified forms of the contents described herein within the scope of the present invention.

[0021] The present invention relates to a method for regenerating a waste precursor for a lithium secondary battery cathode active material, and relates to a method for regenerating a new cathode active material having suitable specifications and a good appearance by utilizing a cathode active material classified as a waste precursor, which has a composition that deviates from a standard during the cathode active material manufacturing process or has an appearance such as sphericity, specific surface area, particle size, or tap density that deviates from a good product.

[0022] One embodiment of the present invention comprises a first step of preparing a spent precursor solution containing spent precursor sulfate produced by mixing a spent precursor (NCM(OH)2) for a positive electrode active material containing Ni, Co, and Mn with a leaching solution containing sulfuric acid and a reducing agent; a second step of preparing a transition metal solution containing a transition metal sulfate produced by mixing nickel sulfate, cobalt sulfate, and manganese sulfate in water; a third step of preparing a mixed precursor solution by mixing 2.5 to 4 parts by weight of a transition metal solution with 1 part by weight of the spent precursor solution; a fourth step of introducing an aqueous ammonia solution as a complexing agent into a reactor containing distilled water and injecting nitrogen gas; and a fifth step of supplying the mixed precursor solution and NaOH as a precipitating agent to the reactor, at a ratio of 1.8 to 2.3 moles of NaOH with respect to 1 mole of the sum of the spent precursor sulfate and the transition metal sulfate contained in the mixed precursor solution, thereby precipitating the precursor for the positive electrode active material.

[0023] In this way, in the process of regenerating a spent precursor for a positive electrode active material according to the present invention, a spent precursor solution and a new transition metal solution (not a spent precursor) are used together, and the first step of preparing the spent precursor solution and the second step of preparing the new transition metal solution are not necessarily performed in the order described above, but may be performed simultaneously or the first step may be performed after the second step.

[0024] First, the first step is a step for preparing a spent precursor solution containing spent precursor sulfate produced by mixing a spent precursor (NCM(OH)2) for a cathode active material containing Ni, Co, and Mn with a leaching solution containing sulfuric acid and a reducing agent. This step is a step for preparing a spent precursor solution in which the spent precursor is dissolved in order to recycle the spent precursor. The spent precursor can be used as is, or can be used in a pretreated state through processes such as cutting, crushing, and particle size sorting.

[0025] The above-mentioned precursor is specifically Ni xCo y Mn 1-x-y It may be a substance containing a high nickel content, expressed by the chemical formula of (OH)2, containing 2 moles of hydroxyl groups (OH) for 1 mole of the sum of nickel (Ni), cobalt (Co), and manganese (Mn), and x being 0.80 to 0.90 and y being 0.005 to 0.08.

[0026] Specifically, this step can be performed by preparing a spent precursor, preparing a leaching solution containing water, sulfuric acid, and a reducing agent, mixing the spent precursor and the leaching solution, stirring, and heating to dissolve the cathode active material in the leaching solution. Through this process, a spent precursor sulfate is produced, and the spent precursor sulfate can be obtained in the form of a spent precursor solution dissolved in a solvent.

[0027] At this time, the mixed waste precursor, water, sulfuric acid, and reducing agent may be mixed so that the molar ratio of the waste precursor, sulfuric acid, and reducing agent is 1:0.9 to 1.1:0.3 to 3.8, preferably 1:1:0.3 to 3.8, and the solid-liquid ratio of the waste precursor solution is 0.067 to 0.125. Here, the solid-liquid ratio may be defined by the following [Formula 1].

[0028] [Formula 1]

[0029] The above-mentioned leaching solution is a substance for effectively dissolving the waste precursor, and among these, water is included for controlling the solid-liquid ratio, and may be at least one of purified water, distilled water, and deionized water.

[0030] The above sulfuric acid and reducing agent are included to dissolve the spent precursor, and although sulfuric acid is effective in dissolving the spent precursor, sulfuric acid is a hazardous substance in itself, so as the content increases, not only does the work risk increase, but if the content is excessive, the amount of sulfur contained in the regenerated positive electrode active material ultimately produced through the regeneration process increases, which may cause problems such as an additional sulfur removal process or an increase in the time and cost required for the sulfur removal process. On the other hand, if the amount of sulfuric acid is insufficient, the spent precursor is not completely dissolved, so it is preferable to include it in the molar ratio described above.

[0031] The above reducing agent is a substance included to dissolve the spent precursor together with sulfuric acid, and formic acid can be used as the reducing agent. Conventionally, hydrogen peroxide was used as a reducing agent, but hydrogen peroxide generates oxygen through a chemical reaction, and the oxygen thus generated forms a metal oxide during the coprecipitation of the regenerated precursor in the subsequent step, so that the composition of the newly generated regenerated precursor changes, and the problem of it being classified as a spent precursor easily occurs. In addition, the generated oxygen may cause bubbles to form in the reactor, causing problems such as the reactor overflowing or exploding, and this may deteriorate the safety of the working environment, so there was a problem that the use of hydrogen peroxide was not easy.

[0032] On the other hand, in the case of formic acid, it effectively dissolves the spent precursor without generating metal oxides due to oxygen generation, and can be effectively recovered through distillation, so it has the advantage of being able to obtain a recycled precursor of consistent quality and being easy to use. If formic acid is insufficient, it is difficult to completely dissolve the spent precursor, and if formic acid is excessive, the unrecovered residual formic acid becomes a hard powder in the powder process after the precursor drying process, which makes it difficult to powderize. Therefore, it is preferable to use formic acid in the molar ratio described above.

[0033] In addition, the solid-liquid ratio, which is the weight of the waste precursor relative to the volume of the leaching solution containing water, sulfuric acid, and a reducing agent, may be 0.067 to 0.125. If the solid-liquid ratio is outside the above range, there is a problem that the waste precursor is not completely dissolved. Therefore, it is preferable to mix the waste precursor and the leaching solution so that the solid-liquid ratio is maintained within the above range.

[0034] In the first step, after mixing the waste precursor and the leaching solution, stirring and heating may be performed for effective dissolution. If the heating temperature is too low, dissolution may not occur, and if the heating temperature is excessively high, rapid reaction may cause poor work safety. Therefore, it is preferable to perform heating in a temperature range of 60 to 80°C for safe, stable, and effective dissolution.

[0035] The concentration of the waste precursor solution obtained through this process can be 0.7 to 1.4 M.

[0036] The second step is a step of preparing a transition metal solution containing transition metal sulfate produced by mixing nickel sulfate, cobalt sulfate, and manganese sulfate in water.

[0037] This step is a step for producing a transition metal sulfate by mixing nickel sulfate, cobalt sulfate, and manganese sulfate, which are precursors of the positive electrode active material, in water. Through this process, a transition metal solution in which the transition metal sulfate is dissolved in water can be prepared. In this step, the ratios of nickel sulfate, cobalt sulfate, and manganese sulfate are not particularly limited, and their mixing ratio can be appropriately set according to the composition of the regenerated positive electrode active material to be ultimately produced. At this time, the precursors and water can be mixed so that the concentration of the transition metal solution becomes 1.6 to 3.7 M.

[0038] The third step is a step for preparing a mixed precursor solution by mixing a spent precursor solution and a transition metal solution. When a regenerated cathode active material is manufactured using a spent precursor solution alone, it is difficult to form the nickel, cobalt, and manganese of the regenerated cathode active material into the target composition. In particular, when a spent precursor classified as a spent precursor due to an insufficient composition is used as a raw material, there is a problem that the composition of the regenerated cathode active material manufactured using it is poor and is classified as a spent precursor again. Therefore, in order to adjust the composition ratio of nickel, cobalt, and manganese contained in the cathode active material, it is preferable to mix the transition metal solution manufactured in the second step with the spent precursor solution to manufacture a mixed precursor solution having the target composition, and to manufacture the cathode active material using the same.

[0039] At this stage, the waste precursor solution and the transition metal solution can be mixed in a ratio of 2.5 to 4 parts by weight of the transition metal solution to 1 part by weight of the waste precursor solution.

[0040] The fourth step is a step of introducing an aqueous ammonia solution, which is a chelating agent, into a reactor containing distilled water and injecting nitrogen gas. The introduction of the chelating agent causes the metal ions and ammonia to form a complex, which facilitates the precipitation of the regenerated precursor in the subsequent step. The concentration and amount of the aqueous ammonia solution may be appropriately adjusted depending on the specifications of the target regenerated precursor, and preferably, the chelating agent may be introduced so that the concentration of ammonia per 1 L of the mixed precursor solution to be introduced becomes 0.2 to 0.8 M. In this step, the temperature is preferably maintained at 50 to 60°C for easy complex formation and mixing, and the temperature of the reactor may be maintained at this level in the subsequent step. In addition, stirring may be performed, if necessary, for easy stirring.

[0041] At this stage, co-precipitation is carried out in a non-oxidizing atmosphere by injecting a gas containing only nitrogen into the reactor.

[0042] Next, the fifth step is a step of supplying a mixed precursor solution and a precipitant, NaOH, to the reactor to precipitate a precursor for the positive electrode active material. Specifically, this step is a step of supplying a mixed precursor solution and a precipitant to a reactor containing a complexing agent aqueous solution maintained at a temperature range of 50 to 60°C and injected with nitrogen gas to form a precipitate. Stirring may be performed, if necessary, to ensure smooth reaction and precipitation.

[0043] At this stage, the pH can be controlled in the range of 10.0 to 12.5 to ensure the quality of the regenerated precursor meets the target specifications. In addition, the amount of the mixed precursor solution and the precipitant NaOH can be adjusted so that the NaOH is added at a ratio of 1.8 to 2.3 moles per mole of the total sulfate, i.e., the total sulfate of the spent precursor sulfate and the transition metal sulfate contained in the mixed precursor solution, and preferably, the NaOH is added at a ratio of 2 moles per mole of the total sulfate. At this time, the NaOH can be in an aqueous solution state, and the concentration is not particularly limited.

[0044] Through these steps, a regenerated precursor, which is a precursor for a positive electrode active material, can be obtained, and if the particle size of the precursor for a positive electrode active material thus obtained is the target size, the coprecipitation reaction can be completed with the fifth step, but if the particle size needs to be increased by growing the regenerated precursor, an additional step can be performed.

[0045] Specifically, the supernatant of the reaction-completed solution obtained through the fifth step is removed, a mixed precursor solution and a complexing agent are additionally added, and NaOH is added to maintain the same pH as the fifth step, thereby growing a precursor precipitate for a positive electrode active material, which can be grown as one step, and this step can be repeated at least once.

[0046] Here, since the precursor precipitate for the positive electrode active material formed through the fifth step is precipitated in the reaction completion solution, only the supernatant can be removed to secure space in the reactor for additional reactants to be added.

[0047] The mixed precursor solution and complexing agent can be added at a ratio of 0.2 to 1.0 moles of ammonia per mole of the transition metal contained in the mixed precursor solution. If these reactants are not stirred when added, the previously prepared regenerated precursor will not grow, but rather a new regenerated precursor will be created, making particle size control difficult. Therefore, it is preferable to first stir the reactor and adjust the temperature to 50 to 60°C so that the previously prepared regenerated precursor is suspended before adding the mixed precursor solution and complexing agent.

[0048] In this process, reaction conditions such as the amount of reactant input, the rate of reactant input, the stirring rate, and the reaction time can be appropriately adjusted according to the capacity of the reactor and the specifications of the target precursor, and by repeating these steps one or more times, the co-precipitation reaction for controlling the particle size of the regenerated precursor can be completed.

[0049] When the coprecipitation reaction is completed in this way, a washing step may be performed to wash the regenerated precursor using purified water such as distilled water, purified water, deionized water, or NaOH aqueous solution to remove impurities generated during the reaction. Afterwards, a drying step may be performed to dry the regenerated precursor at about 80 to 120°C for 12 to 24 hours, and the drying temperature and time may be performed under conditions outside the above temperature and time ranges depending on the characteristics of the regenerated precursor. In particular, when the manganese content is high, such as about 40% or more, manganese oxide may be generated at high temperatures, so in such cases, it is preferable to perform drying at a low temperature of 100°C or lower.

[0050]

[0051] Hereinafter, the specific functions and effects of the present invention will be explained through an example of the present invention. However, this is presented as a preferred example of the present invention, and the scope of the present invention is not limited by the example.

[0052] [Experimental Example 1]

[0053] NCM(OH)2 waste precursor (Ni: Co: Mn = 83:5:12 mol%) was mixed with a leaching solution containing deionized water, sulfuric acid, and a reducing agent, and stirred at 500 rpm to prepare a waste precursor solution.

[0054] At this time, the solid-liquid ratio defined by [Formula 1] was fixed to 0.1, and the molar ratio of the spent precursor, sulfuric acid, and reducing agent was changed, and in the case of some samples, the spent precursor solution was prepared by changing the reaction temperature and reaction time. The content of deionized water was increased or decreased to adjust the mole number and solid-liquid ratio, and the solubility of the spent precursor solution prepared in this way was evaluated, and the results are shown in Table 1. The dissolution rate for determining the solubility was calculated by putting the spent precursor solution into a depressurized flask, measuring the initial weight of the spent precursor (w1) and the weight of the spent precursor remaining after depressurization and drying (w2), and using [Formula 2].

[0055] [Formula 2]

[0056] Sample number Molar ratio Temperature (℃) Reaction time (min) Solubility (%) Waste precursor Sulfuric acid Formic acid 11--80 1800 211.57-80 1800 3110.160 60 2.54 110.360 90 100 5110.660 90 100 6111.260 90 100 7111.860 90 100 8112.460 90 100 9113.880 60 100

[0057] As a result of the experiment, when looking at samples 1, 2, and 3, when only sulfuric acid was used to dissolve the spent precursor under the same conditions, no dissolution occurred at all, but when only a small amount of formic acid was added, some dissolution occurred under milder reaction conditions.

[0058] Furthermore, when examining Samples 3 through 9 together, despite the identical experimental conditions (temperature, reaction time), a very low dissolution rate was observed in Sample 3, indicating an insufficient formic acid content. Even in the case of Sample 9, which had a high formic acid content, the waste precursor was found to be completely dissolved.

[0059] Therefore, as a result of this experiment, it was confirmed that in order to completely dissolve the waste precursor for recycling, a mixture of sulfuric acid and formic acid should be used, but it is preferable to use 0.9 to 1.1 moles of sulfuric acid and 0.3 to 3.8 moles of formic acid per mole of the waste precursor, and in the case of sulfuric acid, it is most preferable to use 1 mole.

[0060] [Experimental Example 2]

[0061] The same experiment as Experimental Example 1 was performed, but the molar ratio of spent precursor, sulfuric acid, and formic acid was fixed at 1:1:0.3, and the amount of deionized water was increased or decreased to vary the solid-liquid ratio to prepare a spent precursor solution. The dissolution rate of the spent precursor solution thus prepared was confirmed using the same method as Experimental Example 1 and is shown in Table 2.

[0062] Sample number Molar ratio Solid-liquid ratio Temperature (℃) Reaction time (min) Solubility (%) Waste precursor Sulfuric acid Formic acid 10110.30.067609010011110.30.083609010012110.30.100609010013110.30.125609010014110.30.133609099.4

[0063] Experimental results confirmed that, under identical conditions, dissolution rates decreased when the solid-liquid ratio exceeded 0.125. While a lower solid-liquid ratio does not affect dissolution rates, the relatively low concentration reduces productivity when using a reactor of the same capacity. Furthermore, the increased volume of the solution increases storage and handling costs and energy consumption, making excessively low solid-liquid ratios undesirable.

[0064] Therefore, through this experiment, it was confirmed that the appropriate high-value-added ratio is 0.067 to 0.125, and in particular, considering various factors such as productivity, storability, and handleability, it was confirmed that 0.083 to 0.125 is desirable, and the range of 0.100 to 0.125 is the most desirable.

[0065] [Experimental Example 3]

[0066] The same test as Experimental Example 1 was performed, but the molar ratio of spent precursor, sulfuric acid, and formic acid was fixed at 1:1:0.3, the solid-liquid ratio was fixed at 0.1, and the spent precursor dissolution temperature was changed to prepare a spent precursor dissolution solution. The dissolution rate of each sample was calculated as in Experimental Example 1 and recorded in Table 3.

[0067] Sample number Molar ratio Solid-liquid ratio Temperature (℃) Reaction time (min) Solubility (%) Spent precursor Sulfuric acid Formic acid 15110.30.1501805116110.30.1609010017110.30.18060100

[0068] The experimental results confirmed that 100% dissolution of the waste precursor occurred only when the temperature was 60℃ or higher, and that the reaction time shortened as the temperature increased. On the other hand, when the temperature exceeded 80℃, the amount of hazardous substances such as sulfur gas released into the atmosphere increased rapidly due to the violent reaction, so it was confirmed that the reaction temperature of the waste precursor dissolution solution should be 60-80℃ for environmental reasons and the safety of the work environment.

[0069] [Experimental Example 4]

[0070] The same experiment as Experimental Example 1 was performed using NCM(OH)2 waste precursor (Ni:Co:Mn = 87.2:8.3:4.5 mol%), and various experiments were performed by changing the molar ratio of formic acid and temperature conditions. The dissolution rate of each sample was calculated using the same method as Experimental Example 1 and is shown in Table 4.

[0071] Sample number Molar ratio Solid-liquid ratio Temperature (℃) Reaction time (min) Solubility (%) Spent precursor Sulfuric acid Formic acid 18110.20.16018031.619110.30.1506028.220110.30.1609010021110.30.1806010022113.80.18060100

[0072] Experimental results showed that even waste precursors with higher Ni content showed lower dissolution rates when the formic acid content was insufficient, as in sample 18, or when the temperature was low, as in sample 19.

[0073] Therefore, through this experiment, the same results as Experiment 1 and Experimental Example 3 could be derived, and it was confirmed that the molar ratio of the spent precursor, sulfuric acid, and formic acid, the solid-liquid ratio between the spent precursor and the leaching solution, and the temperature conditions during dissolution can be equally applied to the NCM(OH)2 spent precursor containing a high nickel content. Specifically, it can be applied to the NCM(OH)2 spent precursor having about 80 to 90 mol% of nickel in nickel, cobalt, and manganese.

[0074] The method for regenerating a waste precursor for a lithium secondary battery cathode material according to the present invention supplies NaOH as a precipitant to a mixed precursor solution in which a waste precursor solution containing a waste precursor sulfate and a transition metal solution containing a transition metal sulfate are mixed, thereby precipitating a precursor for a cathode active material, thereby improving the regeneration efficiency of the waste precursor without generating additional waste precursors again during the regeneration process, and improving the process efficiency and production quality by recycling the solution used for regeneration, and thus has industrial applicability.

Claims

1. A first step of preparing a spent precursor solution containing spent precursor sulfate produced by mixing a spent precursor (NCM(OH)2) for a cathode active material containing Ni, Co and Mn with a leaching solution containing sulfuric acid and a reducing agent; A second step of preparing a transition metal solution containing transition metal sulfate produced by mixing nickel sulfate, cobalt sulfate and manganese sulfate in water; A third step of preparing a mixed precursor solution by mixing 2.5 to 4 parts by weight of a transition metal solution with 1 part by weight of a waste precursor solution; Step 4: Injecting an aqueous ammonia solution as a complexing agent into a reactor containing distilled water and injecting nitrogen gas; and A fifth step of supplying a mixed precursor solution and a precipitant, NaOH, to the above reactor, at a ratio of 1.8 to 2.3 moles of NaOH based on 1 mole of the mixture of waste precursor sulfate and transition metal sulfate contained in the mixed precursor solution, thereby precipitating a precursor for a positive electrode active material; In the first step above, when preparing the spent precursor solution, the molar ratio of the mixed spent precursor, sulfuric acid and reducing agent is 1:1:0.3~3.

8. The above reducing agent is formic acid, A method for regenerating a waste precursor for a positive electrode material of a lithium secondary battery, characterized in that the content of nickel contained in the waste precursor for the positive electrode active material is 80 to 90 mol%.

2. In paragraph 1, A method for regenerating a waste precursor for a lithium secondary battery cathode material, characterized in that the solid-liquid ratio of the waste precursor solution manufactured in the first step, as defined by the following [Formula 1], is 0.067 to 0.

125. [Formula 1] 3. In paragraph 1, A method for regenerating a waste precursor for a lithium secondary battery cathode material, characterized in that the first step is performed at a temperature range of 60 to 80°C.

4. In paragraph 1, When removing the supernatant of the reaction solution containing the precursor precipitate for the positive electrode active material obtained through the above 5th step and further adding the mixed precursor solution, the ammonia aqueous solution as a complexing agent, and NaOH to grow the precursor precipitate for the positive electrode active material is defined as one step, A method for regenerating a waste precursor for a lithium secondary battery cathode material, characterized in that the above step is performed once or is repeated two or more times.

Images