Method for recovering valuable metals from an NCM cathode material

Abstract

The application relates to the field of battery technology, in particular to a recovery method of valuable metals in NCM positive materials. The recovery method comprises the following steps: mixing NCM positive materials, inorganic acid, reducing agent and water, carrying out filtration after leaching treatment to obtain a leaching solution; mixing the leaching solution with a carbonate, carrying out filtration after heating treatment to obtain lithium carbonate and a nickel-cobalt-manganese carbonate solution; adjusting the pH value of the nickel-cobalt-manganese carbonate solution to 8 by using alkaline hydroxide, carrying out filtration after no more precipitates are generated to obtain nickel-cobalt-manganese hydroxide. The recovery method shortens the recovery process flow, has high recovery rate, reduces the use of organic reagents and extractants, avoids the introduction of impurity ions, and reduces the recovery cost.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to a method for recovering valuable metals from NCM cathode materials. Background Technology

[0002] In recent years, new energy vehicles have been widely promoted and used, and lithium-ion batteries, as the mainstream power supply method for these vehicles, have also been extensively used. Among them, ternary lithium-ion batteries, with their high energy density and high charging efficiency, are used in most mid-to-high-end new energy vehicles. However, lithium-ion batteries will reach the end of their service life after 8 to 10 years due to performance degradation. Lithium nickel cobalt manganese oxide (LiNi) batteries are particularly prone to this degradation. x Co y Mn 1-x-y O2 (NCM) is a widely used cathode material, applied in mid-to-high-end vehicles.

[0003] Lithium, cobalt, nickel, and manganese in waste NCM cathode materials are key metal resources that my country heavily relies on for imports. Co accounts for 5%-20%, Ni 5%-12%, Mn 7%-10%, and Li 2%-5%, generally higher than the grades of these metals in natural ores, thus making them highly valuable for recycling. However, waste NCM cathode materials contain various heavy metals and organic matter, posing a potential threat to the environment and potentially causing heavy metal and water pollution. If waste lithium-ion batteries are disposed of improperly without proper treatment, they will cause significant harm to ecosystems and human health. Therefore, driven by both economic and environmental benefits, the recycling of waste NCM cathode materials is of great significance.

[0004] Current research generally categorizes electrode material recovery methods into direct remediation and regeneration, pyrometallurgical recovery, biological recovery, and hydrometallurgical recovery. Among these, hydrometallurgical technology, with its simplicity, mild operating conditions, and environmentally friendly characteristics, has become a focal point in both laboratory research and industrial production. Hydrometallurgical recovery can be divided into two process routes: full metal leaching and selective Li leaching. The recovery of Ni, Co, and Mn typically involves fractional extraction of different valuable elements from the leachate, followed by precipitation or salting-out of the extracted elements to prepare raw materials. However, this type of recovery method has a lengthy process, easily leading to waste of valuable metals. Furthermore, the use of large amounts of extractant results in high costs, making it unsuitable for large-scale industrial production.

[0005] Patent CN118206161A discloses a method for recycling waste ternary lithium batteries to prepare ternary precursors, including the following steps: A) Pretreatment: manually peeling off the positive electrode active material and dissolving the adhesive with an organic solvent to obtain ternary positive electrode powder; B) Leaching: leaching with a eutectic solvent and filtering to obtain a nickel-cobalt-manganese leaching solution; C) Precursor preparation: adding a certain amount of nickel salt, cobalt salt, and manganese salt to the leaching solution and preparing the ternary precursor by co-precipitation. The drawbacks of this method are: 1. The process of recycling the positive electrode material is complex and inefficient. 2. The eutectic solvent used in the leaching process is composed of tetrabutylammonium chloride, thiophenecarboxyltrichloroacetone, and benzoyltrichloroacetone; the use of a large amount of organic reagents makes the recycling cost too high. Summary of the Invention

[0006] In view of this, the present invention provides a method for recovering valuable metals from NCM cathode materials. This recovery method shortens the recovery process, achieves high recovery rates, reduces the use of organic reagents and extractants, avoids the introduction of impurity ions, and lowers recovery costs.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] In a first aspect, the present invention provides a method for recovering valuable metals from NCM cathode materials, comprising the following steps:

[0009] S11, NCM cathode material, inorganic acid, reducing agent and water are mixed, and after leaching treatment, the mixture is filtered to obtain leachate;

[0010] S12, the leachate is mixed with carbonate, heated and then filtered to obtain lithium carbonate and nickel cobalt manganese carbonate solution.

[0011] S13, the pH of the nickel cobalt manganese carbonate solution was adjusted to 8 using alkaline hydroxide, and after no more precipitation was produced, it was filtered to obtain nickel cobalt manganese hydroxide.

[0012] Preferably, the lithium leaching rate of the recovery method of the present invention is greater than 80%.

[0013] Preferably, the recycling method of the present invention has a nickel leaching rate of greater than 80%.

[0014] Preferably, the recycling method of the present invention has a cobalt leaching rate of greater than 80%.

[0015] Preferably, the recovery method of the present invention has a manganese leaching rate of greater than 80%.

[0016] In an embodiment of the present invention, in step S11, the inorganic acid includes at least one of sulfuric acid, hydrochloric acid, and nitric acid.

[0017] In embodiments of the present invention, the reducing agent includes hydride metal salts and / or borohydride metal salts, and the metal element in the reducing agent includes at least one of Li, Ni, Co, Mn, and Al, but does not include impurity elements.

[0018] In a specific embodiment of the present invention, the reducing agent includes at least one of lithium aluminum hydride, lithium borohydride, and nickel borohydride.

[0019] As a preferred option, H of inorganic acids + The molar ratio of Li, Ni, Co, and Mn in the total amount of NCM cathode material is (0.8–1.2):1.

[0020] Preferably, the molar ratio of the amount of electrons transferred by the reducing agent in the reduction reaction to the total amount of Li, Ni, Co, and Mn in the NCM cathode material is (0.8–1.2):1.

[0021] Preferably, the leaching treatment time is 0.5 to 4 hours.

[0022] In an embodiment of the present invention, in step S12, the carbonate includes at least one of aluminum carbonate, magnesium carbonate, nickel carbonate, cobalt carbonate, and manganese carbonate.

[0023] Preferably, the molar ratio of carbonate ions in the carbonate to the total amount of Li, Ni, Co, and Mn in the leachate is (0.8–1.2):1.

[0024] Preferably, in step S12, the heating temperature is 90–100°C and the heating time is 0.5–1.5 h.

[0025] In an embodiment of the present invention, in step S13, the alkaline hydroxide includes at least one of magnesium hydroxide, aluminum hydroxide, and ammonia water.

[0026] In an embodiment of the present invention, step S13 further includes a doping metal element, which includes at least one of Mg and Al.

[0027] Secondly, the present invention provides a method for preparing regenerated NCM cathode material using NCM cathode material, comprising the following steps:

[0028] S21, using any one of the recycling methods of claims 1 to 7, lithium carbonate and nickel cobalt manganese hydroxide are obtained;

[0029] S22, lithium carbonate and nickel cobalt manganese hydroxide are mixed and then sintered in a first and second sintering process to obtain a regenerated NCM cathode material.

[0030] Preferably, the molar ratio of Li in lithium carbonate to Ni, Co, Mn in nickel cobalt manganese hydroxide and the total amount of doped metal elements is (1-1.1):1.

[0031] Preferably, the temperature of the first sintering is 450–500℃, and the holding time of the first sintering is 180–280 min.

[0032] Preferably, the temperature of the second sintering is 800–900℃, and the holding time of the second sintering is 840–960 min.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] (1) The NCM cathode material recycled in the recycling method of the present invention does not require complicated processing, and does not require additional processing of the binder and conductive agent. It can be directly leached and recycled without affecting the subsequent leaching process, thus simplifying the pretreatment process. Furthermore, after leaching, filtration can directly remove the binder and conductive agent.

[0035] (2) The reducing agent and alkali used in the recovery method of the present invention, and the Li, Al, Mg, Ni, Co and Mn metals introduced during the reaction are non-impurity metals. Among them, Al and Mg can be used as doping metals to optimize nickel cobalt manganese hydroxide, and Li, Ni, Co and Mn can be used as supplementary metals. The recovery does not require impurity removal.

[0036] (3) In the recovery method of this invention, the solubility of lithium carbonate decreases with increasing temperature to achieve selective leaching of lithium. Unlike the traditional selective lithium leaching process that yields lithium leaching solution and nickel-cobalt-manganese slag, the process of this invention yields lithium carbonate and nickel-cobalt-manganese carbonate solution, simplifying the recovery of nickel-cobalt-manganese and enriching the selective lithium leaching recovery process.

[0037] (4) In the recycling method of the present invention, the heating temperature is only 90-100℃, and the energy consumption is low. At the same time, the recycling conditions are simple and the requirements for equipment are low.

[0038] (5) The recycling method of this invention avoids extraction processing, greatly shortens the recycling process, and reduces the waste of valuable metals caused by the recycling process. At the same time, it reduces the use of organic reagents and extractants, avoids the introduction of impurity ions, shortens the recycling process, and reduces recycling costs. Attached Figure Description

[0039] Figure 1 This is a process flow diagram for recovering valuable metals from the NCM cathode material of this invention. Detailed Implementation

[0040] This invention discloses a method for recovering valuable metals from NCM cathode materials. Those skilled in the art can refer to this document and appropriately modify the process parameters to achieve the desired result. It is particularly important to note that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0041] In the description of this invention, it should be noted that the terms "first," "second," etc., are used for descriptive purposes only and are not intended to indicate or imply relative importance.

[0042] In the description of this invention, the list of items connected by the term "at least one of" or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.

[0043] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges or individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0044] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0045] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0046] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0047] Specifically, the present invention adopts the following technical solution:

[0048] In a first aspect, the present invention provides a method for recovering valuable metals from NCM cathode materials, comprising the following steps:

[0049] S11, NCM cathode material, inorganic acid, reducing agent and water are mixed, and after leaching treatment, the mixture is filtered to obtain leachate;

[0050] S12, the leachate is mixed with carbonate, heated and then filtered to obtain lithium carbonate and nickel cobalt manganese carbonate solution.

[0051] S13, the pH of the nickel cobalt manganese carbonate solution was adjusted to 8 using alkaline hydroxide, and after no more precipitation was produced, it was filtered to obtain nickel cobalt manganese hydroxide.

[0052] The recycling method of this invention can be used not only for the recycling of valuable metals in waste NCM cathode materials, but also for the recycling of valuable metals in non-waste NCM cathode materials.

[0053] Preferably, the lithium leaching rate of the recovery method of the present invention is greater than 80%. Exemplarily, the lithium leaching rate of the recovery method of the present invention is any value from 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, or any value within the range of any pair of the above values.

[0054] Preferably, the nickel leaching rate of the recovery method of the present invention is greater than 80%. Exemplarily, the nickel leaching rate of the recovery method of the present invention is any value from 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, or any value within the range of any pair of the above values.

[0055] Preferably, the cobalt leaching rate of the recovery method of the present invention is greater than 80%. Exemplarily, the cobalt leaching rate of the recovery method of the present invention is any value from 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, or any value within the range of any pair of the above values.

[0056] Preferably, the leaching rate of manganese by the recovery method of the present invention is greater than 80%. Exemplarily, the leaching rate of manganese by the recovery method of the present invention is any value from 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, or any value within the range of any pair of the above values.

[0057] In this embodiment of the invention, in step S11, the inorganic acid includes at least one of sulfuric acid (H2SO4), hydrochloric acid (HCl), and nitric acid (HNO3). The inorganic acids used are all strong acids, which can better leach Li, Ni, Co, and Mn from the cathode material, while also having low leaching costs.

[0058] In this embodiment of the invention, the reducing agent includes hydride metal salts and / or borohydride metal salts, and the metal element in the reducing agent includes at least one of Li, Ni, Co, Mn, and Al, excluding impurity elements. The advantages of the above-mentioned reducing agent are: ① The reducing agent can reduce high-valence valuable metals in ternary cathode materials to low-valence states; ② The reducing agent can disrupt the layered structure of the ternary cathode material, allowing the inorganic acid to dissolve more of the valuable metals Li, Ni, Co, and Mn in the cathode material into the solution, thereby improving the recovery rate; ③ The non-impurity metals Li, Ni, Co, Mn, and Al in the reducing agent also play a supplementary role while leaching and removing impurities; ④ The reducing agent does not include impurity elements (impurity elements in the reducing agent refer to other elements that ultimately exist in the recovered product and are useless, harmful, or even negatively affect the performance of the recovered product, such as impurity elements like Na), eliminating the need for impurity removal in subsequent recovery processes and reducing the recovery steps.

[0059] In a specific embodiment of the present invention, the reducing agent includes at least one of lithium aluminum hydride (LiAlH4), lithium borohydride (LiBH4), and nickel borohydride (Ni(BH4)2).

[0060] In specific embodiments of the present invention, the reducing agent can also be Na2S2O3, Na2S2O5, or Na2SO3. Since these reducing agents do not introduce doped metals such as Al, Li, or Ni, the electrical properties of the subsequently prepared ternary cathode material are relatively poor. Furthermore, because Na... + The introduction of extractant requires extraction to obtain Li, Ni, Co and Mn elements in the subsequent recovery process. The extraction process will cause the loss of valuable metals, resulting in a low recovery rate. At the same time, the use of extractant increases the recovery cost and has low economic benefits.

[0061] As a preferred option, H of inorganic acids +The molar ratio of Li, Ni, Co, and Mn in the total amount of NCM cathode material is (0.8–1.2):1. For example, the H+ of inorganic acids... + The molar ratio of Li, Ni, Co, and Mn to the total amount of NCM cathode material is any one of the following values: 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, or any value within the range formed by any two of the above values. If the ratio is too small, it will be difficult to leach all the valuable metals; if the ratio is too large, it will be detrimental to the subsequent pH adjustment.

[0062] Preferably, the molar ratio of the amount of electrons transferred by the reducing agent in the reduction reaction to the total amount of Li, Ni, Co, and Mn in the NCM cathode material is (0.8–1.2):1. For example, the molar ratio of the amount of electrons transferred by the reducing agent in the reduction reaction to the total amount of Li, Ni, Co, and Mn in the NCM cathode material can be any value from 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, or any value within the range of any two of the above values. If the ratio is too small, the reduction capacity for nickel, cobalt, and manganese will be insufficient; if the ratio is too large, it will easily lead to waste of the reducing agent.

[0063] Preferably, the leaching time is 0.5 to 4 hours. For example, the leaching time can be any value from 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, and 4h, or any value within a range formed by any two of the above values. If the time is too short, it is difficult to leach all the valuable metals; if the time is too long, the time cost increases.

[0064] In step S11 of this invention, for the raw material preparation section for NCM cathode material recycling, only the cathode material needs to be obtained; no additional treatment is required for the binder (e.g., PVDF) and conductive agent (e.g., acetylene black), and this will not affect the subsequent leaching process. Furthermore, filtration after leaching can directly remove the binder and conductive agent.

[0065] In this embodiment of the invention, in step S12, the carbonate includes at least one of aluminum carbonate (Al2(CO3)3), magnesium carbonate (MgCO3), nickel carbonate (NiCO3), cobalt carbonate (CoCO3), and manganese carbonate (MnCO3). The carbonate provides a large amount of carbonate ions. Under heating conditions, the solubility of lithium carbonate decreases with increasing temperature, gradually precipitating out. Filtration yields lithium carbonate residue and a nickel-cobalt-manganese-rich solution. The Al, Mg, Ni, Co, and Mn metals introduced during the reaction are non-impurity metals. Al and Mg can be used as dopant metals to optimize nickel-cobalt-manganese carbonate, while Ni, Co, and Mn can be used as supplementary metals. Recovery does not require impurity removal.

[0066] In this embodiment of the invention, in step S12, the carbonate can also be sodium carbonate (Na2CO3). Since sodium carbonate does not incorporate doped metals such as Al, Mg, Ni, Co, and Mn, the electrical properties of the subsequently prepared ternary cathode material are relatively poor. Furthermore, because Na... + The introduction of extractant requires extraction to obtain Li, Ni, Co and Mn elements in the subsequent recovery process. The extraction process will cause the loss of valuable metals, resulting in a low recovery rate. At the same time, the use of extractant increases the recovery cost and has low economic benefits.

[0067] Preferably, the molar ratio of carbonate ions in the carbonate to the total amount of Li, Ni, Co, and Mn in the leachate is (0.8–1.2):1. For example, the molar ratio of carbonate ions in the carbonate to the total amount of Li, Ni, Co, and Mn in the leachate can be any value from 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, or any value within the range formed by any two of the above values. If the ratio is too small, the leaching rate of Li, Ni, Co, and Mn will decrease; if the ratio is too large, it will easily lead to waste of carbonate.

[0068] Preferably, in step S12, the heating temperature is 90–100°C, and the heating time is 0.5–1.5 h. For example, the heating temperature can be any value from 90°C, 91°C, 92°C, 93°C, 94°C, 95°C, 96°C, 97°C, 98°C, 99°C, and 100°C, or any value within a range of any two of these values. The heating time can be any value from 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h, and 1.5 h, or any value within a range of any two of these values. The solubility of lithium carbonate decreases with increasing temperature. Within the above temperature and time range, a higher recovery rate and lower energy consumption cost can be achieved. If the temperature is too low or the time is too short, the leaching rate of Li will decrease; if the temperature is too high or the time is too long, the energy consumption cost will increase.

[0069] In this embodiment of the invention, in step S13, the alkaline hydroxide includes at least one of magnesium hydroxide, aluminum hydroxide, and ammonia water. When the alkaline hydroxide is magnesium hydroxide or aluminum hydroxide, Mg can be introduced into the nickel cobalt manganese hydroxide precipitate. 2+ And Al 3+ This improves the structure of nickel-cobalt-manganese hydroxide. Furthermore, the aforementioned alkaline hydroxide does not contain impurity elements (such as sodium), eliminating the need for impurity removal during the preparation of the ternary precursor and reducing the recycling process.

[0070] In this embodiment of the invention, in step S13, the nickel cobalt manganese hydroxide further includes a doping metal element, which includes at least one of Mg and Al. The Mg added in the leaching process of step S11 and the pH adjustment process of step S13... 2+ And Al 3+ It can improve the crystallinity and layered structure of ternary NCM cathode materials, thereby enhancing the electrochemical performance of regenerated NCM cathode materials.

[0071] Secondly, the present invention provides a method for preparing regenerated NCM cathode material using NCM cathode material, comprising the following steps:

[0072] S21, The above-mentioned recycling method is used to recover valuable metals from NCM cathode materials to obtain lithium carbonate and nickel cobalt manganese hydroxide;

[0073] S22, lithium carbonate and nickel cobalt manganese hydroxide are mixed and then sintered in a first and second sintering process to obtain a regenerated NCM cathode material.

[0074] Since the formation of ternary NCM cathode materials requires the presence of separate solid precursor structures for lithium and nickel-cobalt-manganese in order to form a good ternary structure, the above-mentioned recycling method is first used to obtain lithium carbonate and nickel-cobalt-manganese hydroxide, which are then sintered to form recycled NCM cathode materials.

[0075] Preferably, the molar ratio of Li in lithium carbonate to Ni, Co, Mn, and the total amount of doped metal elements in nickel cobalt manganese hydroxide is (1–1.1):1. For example, the molar ratio of Li in lithium carbonate to Ni, Co, Mn, and the total amount of doped metal elements in nickel cobalt manganese hydroxide can be any value from 1:1, 1.02:1, 1.04:1, 1.06:1, 1.08:1, 1.1:1, or any value within the range formed by any pair of the above values. Satisfying the above molar ratio ensures that the finally prepared regenerated NCM cathode material has a good layered structure, resulting in excellent electrochemical performance.

[0076] Preferably, the temperature of the first sintering is 450–500°C, and the holding time of the first sintering is 180–280 min. For example, the temperature of the first sintering is any value from 450°C, 460°C, 470°C, 480°C, 490°C, and 500°C, or any value within the range of any two of the above values; the holding time of the first sintering is any value from 180 min, 200 min, 220 min, 240 min, 260 min, and 280 min, or any value within the range of any two of the above values.

[0077] Preferably, the second sintering temperature is 800–900°C, and the holding time for the second sintering is 840–960 min. For example, the second sintering temperature can be any value from 800°C, 820°C, 840°C, 860°C, 880°C, and 900°C, or any value within a range of any two of these values. The holding time for the second sintering can be any value from 840 min, 860 min, 880 min, 900 min, 920 min, 940 min, and 960 min, or any value within a range of any two of these values. The first sintering temperature of the ternary NCM cathode material is relatively low, and the crystal structure of the material is not completely stable after the first sintering, potentially containing defects and impurities. To eliminate these defects and impurities, the ternary NCM cathode material needs to undergo a second sintering. The second sintering temperature is higher than the first sintering temperature, which allows for recrystallization within the material, resulting in a more stable crystal lattice, repair and removal of defects and impurities, and improved battery performance and stability.

[0078] The reagents, instruments, and materials used in this invention can all be obtained through commercial channels.

[0079] The present invention will be further illustrated below with reference to the embodiments:

[0080] Example 1:

[0081] This embodiment uses H2SO4 + LiAlH4 + Al2(CO3)3 to recover waste electrode materials from nickel-cobalt-manganese lithium oxide batteries. See the process flow diagram below. Figure 1 The specific steps are as follows:

[0082] (1) The waste ternary material was roasted at 800℃ for 1h. The slag sample was dissolved in aqua regia and the valuable metals were quantitatively analyzed by ICP-OES for subsequent recovery rate calculation. The composition of valuable metals is shown in Table 1.

[0083] Table 1

[0084] Metal elements Li Ni Co Mn other content 3.83％ 16.57％ 6.16％ 6.54％ 66.9％

[0085] (2) Mix the waste battery electrode material with sulfuric acid (H2SO4:(Li+Ni+Co+Mn) = 0.6 in a molar ratio of H2SO4:(Li+Ni+Co+Mn) (which is an inorganic acid; 1 mol of sulfuric acid can provide 2 mol of H2SO4). + H +Lithium aluminum hydride (LiAlH4:(Li+Ni+Co+Mn)=1.2) with a molar ratio of LiAlH4:(Li+Ni+Co+Mn)=0.5 (belonging to the reducing agent, 1 mol of lithium aluminum hydride can provide 2 mol of electron transfer in the reduction reaction, and the amount of electron transfer provided by lithium aluminum hydride in the reduction reaction is (Li+Ni+Co+Mn)=1) was mixed in an aqueous solution and leached for 2 hours. After filtration, a solution rich in valence metals and leaching residue were obtained.

[0086] (3) Add aluminum carbonate (a carbonate; 1 mol of aluminum carbonate can provide 3 mol of carbonate ions, and the carbonate ion content in aluminum carbonate is 1.2 mol / L) to the metal-rich solution obtained in step (2). Stir in an oil bath at 95°C for 1 hour. After stopping the reaction, filter immediately to obtain lithium carbonate and a nickel-cobalt-manganese-rich solution. Dissolve the lithium carbonate in aqua regia, and determine the lithium content by ICP-OES. The calculated lithium recovery rate is 90.1%.

[0087] (4) Add magnesium hydroxide to the nickel-cobalt-manganese-rich solution obtained in step (3) to adjust the pH to 8. After no more precipitation is produced, filter to obtain nickel-cobalt-manganese-aluminum hydroxide. Dissolve the slag sample in aqua regia and detect the nickel, cobalt and manganese content by ICP-OES. The leaching rates of Ni, Co and Mn in step (4) were calculated to be 95.2%, 93.4% and 92.8%, respectively, basically maintaining the proportion of raw material NCM622.

[0088] (5) The lithium carbonate obtained by leaching and the nickel cobalt manganese aluminum slag obtained by hydroxide were mixed in the ratio of Li:(Al+Ni+Co+Mn)=1.05 and sintered in two stages at 500℃ and 850℃. The first stage sintering time was 180min and the second stage sintering time was 900min to obtain the new ternary cathode material.

[0089] Example 2:

[0090] The difference between this embodiment and Example 1 is that the reducing agent is nickel borohydride with a molar ratio of Ni(BH4)2:(Li+Ni+Co+Mn)=0.3 (1 mol of nickel borohydride can provide 3 mol of electron transfer in the reduction reaction, and the amount of electron transfer provided by nickel borohydride in the reduction reaction is (Li+Ni+Co+Mn)=0.9), and the carbonate is NiCO3:(Li+Ni+Co+Mn)=1 (1 mol of nickel carbonate can provide 1 mol of carbonate, and the amount of carbonate in nickel carbonate is (Li+Ni+Co+Mn)=1).

[0091] The leaching rates of the final product were calculated to be 85.1%, 89.5%, 92.5%, and 90.8%, respectively, for Li, Ni, Co, and Mn.

[0092] Example 3:

[0093] The difference between this embodiment and Example 1 is that the inorganic acid used is hydrochloric acid with a molar ratio of HCl:(Li+Ni+Co+Mn)=1.2 (1 mol of hydrochloric acid can provide 1 mol of H+). + H + (Li+Ni+Co+Mn)=1.2).

[0094] The leaching rates of the final product were calculated to be 88.3%, 90.5%, 89.6%, and 92.4%, respectively, for Li, Ni, Co, and Mn.

[0095] Example 4:

[0096] The difference between this embodiment and Example 1 is that the carbonate used is sodium carbonate with Na2CO3:(Li+Ni+Co+Mn)=1 (1 mol of sodium carbonate can provide 1 mol of carbonate ions, and the carbonate ion content in sodium carbonate is (Li+Ni+Co+Mn)=1); the following extraction step is added between step (3) and step (4) for the separation of Na from nickel, cobalt, and manganese: a certain volume of P507 extractant and P204 extractant are mixed, and after mixing, they are mixed evenly with sulfonated kerosene as the organic phase, and saponified with sodium hydroxide. Then, the saponified organic phase and the nickel-cobalt-manganese-rich solution are placed in a separatory funnel, shaken, and allowed to stand for phase separation. After phase separation, washing is performed, and the extracted organic phase and washing liquid are poured into a separatory funnel, shaken, and allowed to stand for phase separation to further achieve the separation of nickel, cobalt, and manganese.

[0097] The leaching rates of the final product were calculated to be 88.6%, 90.3%, 85.9%, and 91.7%, respectively.

[0098] Example 5:

[0099] The difference between this embodiment and Example 1 is that the reducing agent used is sodium sulfite with a molar ratio of Na2SO3:(Li+Ni+Co+Mn)=0.5 (1 mol of sodium sulfite can provide 2 mol of electron transfer in the reduction reaction, and sodium sulfite can provide electron transfer of:(Li+Ni+Co+Mn)=1 in the reduction reaction); the following extraction step is added between step (3) and step (4) for the separation of Na from nickel, cobalt and manganese: a certain volume of P507 extractant and P204 extractant are mixed, and after mixing, they are mixed evenly with sulfonated kerosene as the organic phase, and saponified with sodium hydroxide. Then, the saponified organic phase and the nickel-cobalt-manganese-rich solution are placed in a separatory funnel, shaken, and allowed to stand for phase separation. After phase separation, washing is performed, and the extracted organic phase and washing liquid are poured into a separatory funnel, shaken, and allowed to stand for phase separation to further achieve the separation of nickel, cobalt and manganese.

[0100] The leaching rates of the final product were calculated to be 86.3%, 80.1%, 83.8%, and 81.2%, respectively, for Li, Ni, Co, and Mn.

[0101] Comparative Example 1:

[0102] A batch of ternary cathode materials was prepared according to the steps of Example 1 disclosed in patent CN118206161A, and the relevant electrical properties were measured. The specific steps are as follows:

[0103] S1. Pretreatment of waste ternary lithium battery cathode materials

[0104] The plastic outer packaging of the waste ternary lithium batteries was manually removed, and then the batteries were discharged in a 30% wt NaCl solution for 24 hours. After that, they were manually disassembled in a laboratory fume hood to obtain positive electrode active material, negative electrode material, separator, aluminum foil and copper foil. The organic solvent N,N-dimethylformamide and the positive electrode active material were mixed at a liquid-to-solid ratio of 10 mL / g and ultrasonically peeled at 70°C with 200 W for 90 min to obtain the ternary lithium battery positive electrode material with the binder removed. The ternary lithium battery positive electrode material with the binder removed was then ball-milled and sieved in a 200-mesh powder vibrating sieve to obtain the pretreated ternary lithium battery positive electrode material powder.

[0105] S2, Preparation of eutectic solvent

[0106] Mix 20g of tetrabutylammonium chloride, 1g of thiophenecarboxyltrichloroacetone and 1g of benzoyltrichloroacetone, add to a glass beaker, then add 100mL of ethanol solvent, place on a magnetic stirrer and mix at 100r / min for 30min until homogeneous. Then add 10g of tartaric acid powder, 10g of oxalic acid powder and 10g of citric acid powder to the glass beaker. Then place the beaker in a water bath and react at 50℃ for 30min to obtain a eutectic solvent.

[0107] S3. Dissolving and leaching the pretreated cathode material powder

[0108] The pretreated cathode material powder and eutectic solvent were mixed at a liquid-to-solid ratio of 20 mL / g and added to a three-necked round-bottom flask. A magnetic stir bar was added to the three-necked round-bottom flask, and a condenser was connected. The three-necked round-bottom flask was heated to 60°C in a water bath and reacted for 100 min to obtain a mixture. The mixture was filtered through a 0.5 μm pore size filter membrane to obtain a metal ion leaching solution and filter residue. The concentration of each metal ion in the metal ion leaching solution was detected to obtain the leaching rate of each metal ion. The leaching rate of Li was 93.12%, that of Ni was 97.55%, that of Co was 97.90%, and that of Mn was 98.15%.

[0109] S4. Preparation of ternary lithium material precursors by co-precipitation method

[0110] Adding a certain amount of NiSO4·6H2O, CoSO4·7H2O, and MnSO4·H2O to the leachate will increase the Ni content in the leachate. 2+ Co 2+ and Mn 2+ The molar ratio of the metals was 5:2:3, and the total concentration of metal ions was 1 mol / L, resulting in a compound metal solution. 2 mol / L ammonia was selected as the complexing agent, and 5 mol / L NaOH solution as the precipitant. The above volumes of the compound metal solution, ammonia, and NaOH solution were mixed and added to a three-necked round-bottom flask as the base solution. The flask was then placed in a constant-temperature water bath, and the compound metal solution, ammonia, and sodium hydroxide solution were added dropwise to the flask using a peristaltic pump at a speed of 100 r / min and a water bath temperature of 50 °C for 2 hours to obtain the reaction mixture. The volume of ammonia added was 100 mL, and the volume of NaOH solution was 40 mL.

[0111] The reaction mixture was allowed to stand for 12 hours, then filtered to obtain a precipitate. The precipitate was washed three times with distilled water and then dried under vacuum at 60°C for 6 hours to obtain Ni. 0.5 Co 0.2 Mn 0.3 (OH)2 precursor.

[0112] Comparative Example 2:

[0113] The difference between this comparative example and Example 1 is that no reducing agent is added.

[0114] The leaching rates of the final product were calculated to be 55.3%, 32.1%, 25.8%, and 20.3%, respectively, for Li, Ni, Co, and Mn.

[0115] Comparative Example 3:

[0116] The difference between this comparative example and Example 1 is that an organic acid is used, specifically acetic acid with a molar ratio of CH3COOH:(Li+Ni+Co+Mn)=1 (1 mol of acetic acid can provide 1 mol of H2). + H + (Li+Ni+Co+Mn)=1).

[0117] The leaching rates of the final product were calculated to be 33.1%, 24.5%, 18.6%, and 50.8%, respectively.

[0118] Battery fabrication and performance testing

[0119] 1. Battery manufacturing

[0120] The cathode material was prepared into a battery using the examples and comparative examples. The specific methods are as follows:

[0121] The battery assembly is divided into the following steps: (1) Preparation of slurry: The positive electrode material, acetylene black and PVDF obtained by firing are mixed in a mass ratio of 8:1:1. The mixture is placed in a glass bottle containing the organic solvent N-methylpyrrolidone and stirred for 4 hours. (2) Slurry coating: A small amount of slurry is dipped with a glass rod and evenly coated on the aluminum foil. After completion, it is transferred to a vacuum drying oven at 100°C for drying for 12 hours. (3) Electrode treatment: In order to prevent the coated positive electrode material from falling off, it is necessary to roll it in a press with a pressure of 2MPa before assembling the battery. Then the electrode is weighed and the data is recorded. (4) Battery assembly: This operation is carried out in a vacuum glove box. The negative electrode shell, spring sheet, gasket, lithium sheet, electrolyte, separator, positive electrode sheet and positive electrode shell are stacked in the order of negative electrode shell, spring sheet, gasket, lithium sheet, electrolyte, separator, positive electrode sheet and positive electrode shell. After completion, the battery is sealed on the assembly machine. After the assembled battery is left to stand for 24 hours, its electrochemical performance is tested.

[0122] 2. Performance Testing Methods

[0123] The prepared batteries were subjected to coin capacity and cycle tests. The specific test methods are as follows:

[0124] Before testing, activate the device using a small current of 0.2C. The ambient temperature is 25℃, and the test voltage is 2.8-4.5V.

[0125] (1) Initial charge / discharge specific capacity test: The initial discharge specific capacity was tested using a 0.2C charge / discharge rate. The formula for calculating the initial charge / discharge efficiency is as follows:

[0126]

[0127] (2) 100-cycle retention rate test: The battery was charged at 0.2C and discharged at 1C for 100 cycles. The retention rate after 100 cycles was:

[0128]

[0129] The results are as follows:

[0130] Table 2

[0131]

[0132] Examples 1-3 show high leaching rates and high final recovery rates in the wet leaching process of valuable metals, and the prepared ternary cathode materials exhibit superior electrical properties.

[0133] Examples 4-5 also showed high leaching rates and high final recovery rates during the wet leaching of valuable metals. However, because Example 4 used sodium carbonate as the carbonate and Example 5 used sodium sulfite as the reducing agent, and these two examples did not introduce doping metals such as Al, Li, Mg, Ni, Co, and Mn, the electrical properties of the prepared ternary cathode materials were worse than those in Examples 1-3. Furthermore, due to the presence of Na... + The introduction of this agent requires extraction to obtain Li, Ni, Co and Mn elements in the subsequent recovery process. The extraction process will cause the loss of valuable metals, and the final recovery rate is lower than that of Example 1. At the same time, the use of the extractant increases the recovery cost and results in low economic benefits.

[0134] Although Comparative Example 1 achieved the highest leaching rate, its operation was complex and required a large amount of organic solvent, resulting in excessively high recycling costs. Furthermore, due to the absence of doped metals such as Al and Li, the final cathode material exhibited inferior electrical performance compared to Examples 1-3.

[0135] Comparative Example 2 did not add a reducing agent, so it would not damage the waste cathode material, resulting in a low leaching rate and a low final recovery rate.

[0136] The organic acid used in Comparative Example 3 has a weak acid leaching effect and a weak ability to leach valuable metals. In addition, the cost of organic acid is higher, so it has little practical significance in production.

[0137] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for recovering valuable metals from NCM cathode materials, characterized in that, Includes the following steps: S11, NCM cathode material, inorganic acid, reducing agent and water are mixed, and after leaching treatment, the mixture is filtered to obtain leachate; S12, the leachate is mixed with carbonate, heated and then filtered to obtain a lithium carbonate and nickel cobalt manganese carbonate solution. S13, the pH of the nickel cobalt manganese carbonate solution is adjusted to 8 using alkaline hydroxide, and after no more precipitation occurs, it is filtered to obtain nickel cobalt manganese hydroxide.

2. The recycling method according to claim 1, characterized in that, The recovery method achieves a lithium leaching rate of greater than 80%. The recovery method achieves a nickel leaching rate of greater than 80%. The recovery method achieves a cobalt leaching rate of greater than 80%. The recovery method achieves a manganese leaching rate of greater than 80%.

3. The recycling method according to claim 1, characterized in that, In step S11, the inorganic acid includes at least one of sulfuric acid, hydrochloric acid, and nitric acid. And / or, the reducing agent comprises a hydride metal salt and / or a borohydride metal salt, and the metal element in the reducing agent comprises at least one of Li, Ni, Co, Mn, and Al, excluding impurity elements; Preferably, the reducing agent includes at least one of lithium aluminum hydride, lithium borohydride, and nickel borohydride; And / or, the H of the inorganic acid + The molar ratio of Li, Ni, Co, and Mn in the total amount of the NCM cathode material is (0.8–1.2):1; And / or, the molar ratio of the amount of electrons transferred by the reducing agent in the reduction reaction to the total amount of Li, Ni, Co, and Mn in the NCM cathode material is (0.8–1.2):1; And / or, the leaching treatment time is 0.5 to 4 hours.

4. The recycling method according to claim 1, characterized in that, In step S12, the carbonate includes at least one of aluminum carbonate, magnesium carbonate, nickel carbonate, cobalt carbonate, and manganese carbonate. And / or, the molar ratio of carbonate ions in the carbonate to the total amount of Li, Ni, Co, and Mn in the leachate is (0.8 to 1.2):

1.

5. The recycling method according to claim 1, characterized in that, In step S12, the temperature of the heat treatment is 90-100℃, and the time of the heat treatment is 0.5-1.5h.

6. The recycling method according to claim 1, characterized in that, In step S13, the alkaline hydroxide includes at least one of magnesium hydroxide, aluminum hydroxide, and ammonia water.

7. The recycling method according to claim 1, characterized in that, In step S13, the nickel cobalt manganese hydroxide further includes a doping metal element, which includes at least one of Mg and Al.

8. A method for preparing regenerated NCM cathode material using NCM cathode material, characterized in that, Includes the following steps: S21, using the recycling method described in any one of claims 1 to 7, lithium carbonate and nickel cobalt manganese hydroxide are obtained; S22, the lithium carbonate and the nickel cobalt manganese hydroxide are mixed, and after a first sintering and a second sintering, a regenerated NCM cathode material is obtained.

9. The method according to claim 8, characterized in that, The molar ratio of Li in the lithium carbonate to Ni, Co, Mn and the total amount of doped metal elements in the nickel cobalt manganese hydroxide is (1-1.1):

1.

10. The method according to claim 8, characterized in that, The temperature of the first sintering is 450-500℃, and the holding time of the first sintering is 180-280 min; And / or, the temperature of the second sintering is 800-900℃, and the holding time of the second sintering is 840-960 min.

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