Recycling method of positive electrode active material

Abstract

The invention provides a recovery method of a positive active material, which is characterized by comprising the following steps: (1) calcining a positive pole piece to obtain a calcined positive pole piece; (2) performing powder removal on the calcined positive pole piece to obtain a powder-removed positive pole piece; and (3) soaking the positive pole piece subjected to powder removal in liquid so as to separate a current collector of the positive pole piece subjected to powder removal from the positive active material, filtering the liquid to obtain the positive active material, and drying the positive active material.

Description

Technical Field

[0001] This application relates to the field of secondary battery technology, and in particular to a method for recycling positive electrode active materials. Background Technology

[0002] In recent years, with the rapid development of the new energy sector, the demand for rechargeable batteries has surged. During the production process of rechargeable batteries (such as electrode coating), a certain proportion of scrap electrodes are generated. Furthermore, some batteries also become unusable during use (e.g., exceeding a certain timeframe). Therefore, the scientific and effective recycling of raw materials from rechargeable batteries for secondary production can generate significant economic, environmental, and resource benefits.

[0003] Current methods for recovering cathode active materials result in low powder yields. Therefore, it is necessary to develop a cathode active material recovery process with a higher powder yield. Summary of the Invention

[0004] This application is made in view of the above-mentioned problems, and its purpose is to provide a method for recovering positive electrode active materials, aiming to achieve a high powder yield.

[0005] The inventors have discovered that by adopting the technical solution of this application, the above-mentioned objectives can be achieved.

[0006] This application provides a method for recovering positive electrode active materials, characterized in that the method includes the following steps:

[0007] (1) The positive electrode sheet is calcined to obtain the calcined positive electrode sheet;

[0008] (2) The calcined positive electrode sheet is de-powdered to obtain a de-powdered positive electrode sheet;

[0009] (3) Soak the de-powdered positive electrode sheet in liquid to separate the current collector and the positive electrode active material of the de-powdered positive electrode sheet, filter the liquid to obtain the positive electrode active material, and dry the positive electrode active material.

[0010] During the loading and calcination process of the positive electrode sheet, some parts are tightly attached, causing the detached powdery positive electrode active material to be trapped in the current collector, making it impossible to collect the positive electrode active material and reducing the powder yield. By using a combination of three steps, namely "calcination + powder removal + soaking", a higher powder yield can be achieved, ultimately achieving the goal of simple, efficient and low-cost physical powder removal.

[0011] In any embodiment, the positive electrode has a major diameter of ≥1cm and a minor diameter of ≥1cm.

[0012] When the positive electrode has a major diameter of ≥1cm and a minor diameter of ≥1cm, it avoids the generation of too much aluminum powder due to excessive grinding of the electrode or too small electrode size, thus resulting in a lower aluminum content in the recovered powder.

[0013] In any embodiment, the calcined positive electrode sheet is de-powdered by mechanical separation.

[0014] In any embodiment, the calcined positive electrode sheet is de-powdered in a drum screen.

[0015] In any embodiment, the calcined positive electrode sheet is de-powdered in a drum sieve containing spherical objects.

[0016] In any embodiment, the diameter of the sphere is 1-30 cm; optionally, the diameter of the sphere is 5-25 cm; optionally, the diameter of the sphere is 10-20 cm.

[0017] In any embodiment, the total volume of the spherical objects accounts for 5-80% of the volume of the drum screen; optionally, the total volume of the spherical objects accounts for 10-70% of the volume of the drum screen; optionally, the total volume of the spherical objects accounts for 20-50% of the volume of the drum screen.

[0018] When the total volume of the spheres accounts for 10-70% of the volume of the drum screen, the duration of step (2) can be effectively shortened, efficiency can be improved, a higher powder yield can be achieved, and the aluminum content in the powder can be controlled to be relatively low.

[0019] In any embodiment, the linear velocity of the drum screen is 0.1-5 m / s; optionally, the linear velocity of the drum screen is 0.5-3.5 m / s; optionally, the linear velocity of the drum screen is 1-2.5 m / s.

[0020] When the linear velocity of the drum screen is 0.5-3.5 m / s, the electrode sheet can be carried to a high altitude by the drum screen and then fall back down. It will not rotate with the drum screen under the action of centrifugal force, so as to achieve the purpose of turning and throwing the electrode sheet and active material in the drum screen, which is conducive to the separation of active material and aluminum foil, thereby achieving a higher powder yield, while controlling the aluminum content in the powder to be relatively low.

[0021] In any embodiment, the duration of step (2) is 0.5 min to 40 min; optionally, the duration of step (2) is 1 min to 20 min; optionally, the duration of step (2) is 2 min to 10 min.

[0022] In any embodiment, in step (3), the liquid includes one or more of deionized water and organic solvents; optionally, the liquid includes deionized water.

[0023] In any embodiment, in step (3), the soaking time is 1-60 min; optionally, the soaking time is 3-30 min; optionally, the soaking time is 5-20 min.

[0024] In any embodiment, in step (3), the de-powdered positive electrode sheet is soaked in liquid and stirred.

[0025] In any embodiment, in step (3), the stirring speed is 50-400 r / min; optionally, the stirring speed is 100-300 r / min; optionally, the stirring speed is 150-250 r / min.

[0026] In any embodiment, in step (3), the stirring time is 1-60 min; optionally, the soaking time is 2-30 min; optionally, the soaking time is 3-20 min.

[0027] In any embodiment, in step (1), the calcination temperature is 300-620℃, optionally 400-600℃, optionally 450-550℃; the calcination time is 0.5-3.5h, optionally 1-3h, optionally 1.5-2.5h. Attached Figure Description

[0028] Figure 1 This is a method for recovering positive electrode active material in one embodiment of this application. Detailed Implementation

[0029] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the secondary battery, its preparation method, and its power-consuming device. However, unnecessary details may be omitted. For example, detailed descriptions of well-known facts and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0030] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0031] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0032] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0033] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0034] 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.

[0035] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0036] Current methods for recovering cathode active materials result in low powder yields. Therefore, it is necessary to develop a cathode active material recovery process with a higher powder yield.

[0037] Based on this, this application proposes a technical solution to solve the above-mentioned technical problems.

[0038] This application provides a method for recovering positive electrode active materials, characterized in that the method includes the following steps:

[0039] (1) The positive electrode sheet is calcined to obtain the calcined positive electrode sheet;

[0040] (2) The calcined positive electrode sheet is de-powdered to obtain a de-powdered positive electrode sheet;

[0041] (3) Soak the de-powdered positive electrode sheet in liquid to separate the current collector and the positive electrode active material of the de-powdered positive electrode sheet, filter the liquid to obtain the positive electrode active material, and dry the positive electrode active material.

[0042] During the loading and calcination process of the positive electrode sheet, some parts are tightly attached, causing the detached powdery positive electrode active material to be trapped in the current collector, making it impossible to collect the positive electrode active material and reducing the powder yield. By using a combination of three steps, namely "calcination + powder removal + soaking", a higher powder yield can be achieved, ultimately achieving the goal of simple, efficient and low-cost physical powder removal.

[0043] In some embodiments, the positive electrode active material includes one or more of lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide.

[0044] In some embodiments, the positive electrode has a major diameter of ≥1 cm and a minor diameter of ≥1 cm.

[0045] When the positive electrode has a major diameter of ≥1cm and a minor diameter of ≥1cm, it avoids the generation of too much aluminum powder due to excessive grinding of the electrode or too small electrode size, thus resulting in a lower aluminum content in the recovered powder.

[0046] In some embodiments, the positive electrode has a major diameter of 1-30 cm and a minor diameter of 1-30 cm.

[0047] In this application, for the positive electrode sheet, any two points are taken on its outer periphery, and the distance between the two points is measured. The longest distance is defined as the "major diameter dimension", and the shortest distance is defined as the "minor diameter dimension".

[0048] In some embodiments, the positive electrode is removed from the secondary battery before step (1). In some embodiments, the positive electrode may be crushed or not. If the positive electrode is not crushed, in step (1), the positive electrode may be in a naturally stacked upright, naturally stacked flat, and / or rolled form. In some embodiments, if the positive electrode is crushed, after crushing, in step (1), the positive electrode has a major diameter of ≥1 cm and a minor diameter of ≥1 cm. By employing this operation, the amount of aluminum powder generated can be reduced, and the amount of aluminum powder carried into the recyclables can be decreased.

[0049] In some embodiments, in step (1), the positive electrode sheet can be crushed first and then calcined; or the positive electrode sheet can be calcined first and then crushed.

[0050] In some embodiments, in step (1), the positive electrode sheet is placed into a crucible, with a crucible weight of 0.5-8.5 kg. In some embodiments, the crucible weight can be 0.5 kg, 1 kg, 1.5 kg, 2 kg, 2.5 kg, 3 kg, 3.5 kg, 4 kg, 4.5 kg, 5 kg, 5.5 kg, 6 kg, 6.5 kg, 7 kg, 7.5 kg, 8 kg, 8.5 kg, or any range of two of the above values ​​or values ​​within that range.

[0051] In some embodiments, in step (1), the calcination temperature is 300-620℃, optionally 400-600℃, optionally 450-550℃; the calcination time is 0.5-3.5h, optionally 1-3h, optionally 1.5-2.5h. In some embodiments, the calcination temperature can be 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, 600℃, 620℃, or any range of any two of the above values, or values ​​within that range. In some embodiments, the calcination time can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, or any range of any two of the above values, or values ​​within that range.

[0052] By calcining under the above conditions, impurities other than the positive electrode active material (such as binders and conductive agents) in the positive electrode film can be removed quickly and effectively, which is beneficial for subsequent powder removal.

[0053] In some embodiments, calcination is performed in an air atmosphere in step (1). In some embodiments, calcination is performed in an oxygen atmosphere in step (1). In some embodiments, calcination is performed in an air atmosphere and oxygen is introduced in step (1).

[0054] In some implementations, the calcined positive electrode sheet is de-powdered by mechanical separation.

[0055] As used in this application, the term "mechanical separation" refers to the operation of separating the positive electrode active material on the positive electrode sheet from the current collector by means of mechanical force (e.g., centrifugal force, gravity, friction, etc.). Examples of mechanical separation include, but are not limited to, removing powder from the positive electrode sheet by means of mechanical force such as centrifugation devices (e.g., drum screens), brushes, sandpaper, scrapers, etc.

[0056] In some embodiments, the calcined positive electrode sheet is de-powdered in a centrifuge. In some embodiments, the calcined positive electrode sheet is de-powdered in a drum screen.

[0057] In this application, "drum screen" refers to a mechanical device widely used in sorting technology that uses gravity and centrifugal force to achieve separation and screening through rotation and the size of the screen openings. The drum screen may contain auxiliary materials such as cubes, cones, cylinders, spheres, or irregularly shaped objects to further improve the efficiency of mechanical separation. Preferably, the drum screen may contain spherical objects.

[0058] In some embodiments, the calcined positive electrode sheet is de-powdered in a drum screen containing spherical objects.

[0059] As mentioned above, during the loading and calcination process of the positive electrode sheet, some parts are tightly adhered, causing the detached powdery positive electrode active material to be trapped in the current collector, making it impossible to collect the positive electrode active material and reducing the powder yield. By using a drum screen containing spherical objects, the calcined positive electrode sheet is continuously tumbled and thrown inside the drum screen, colliding with the spherical objects, and being lifted to a high point before falling down. This can achieve the separation of more than 60% of the positive electrode active material from the current collector (such as aluminum foil). Combined with subsequent soaking and stirring operations, a higher powder yield can be achieved, ultimately achieving the goal of simple, efficient, and low-cost physical de-powdering.

[0060] In some embodiments, in step (2), the powder obtained by de-powdering the calcined positive electrode sheet includes positive electrode active material and a small amount of impurities (such as aluminum shavings), and is further dealuminized (including but not limited to mechanical vibration sieving) and demagnetized to obtain positive electrode active material S1.

[0061] In some embodiments, the diameter of the sphere is 1-30 cm; optionally, the diameter of the sphere is 5-25 cm; optionally, the diameter of the sphere is 10-20 cm. In some embodiments, the diameter of the sphere can be 1 cm, 5 cm, 10 cm, 15 cm, 16 cm, 17 cm, 18 cm, 19 cm, 20 cm, 21 cm, 22 cm, 23 cm, 24 cm, 25 cm, 30 cm, or any range of two of the above values ​​or a value within that range.

[0062] In some implementations, the sphere comprises one or more elastic materials to further improve efficiency.

[0063] In some embodiments, the total volume of the spherical objects accounts for 5-80% of the volume of the drum screen; optionally, the total volume of the spherical objects accounts for 10-70% of the volume of the drum screen; optionally, the total volume of the spherical objects accounts for 20-50% of the volume of the drum screen. In some embodiments, the total volume of the spherical objects may account for 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% of the volume of the drum screen, or any range of two of the above values ​​or values ​​within that range.

[0064] When the total volume of the spheres accounts for 10-70% of the volume of the drum screen, the duration of step (2) can be effectively shortened, efficiency can be improved, a higher powder yield can be achieved, and the aluminum content in the powder can be controlled to be relatively low.

[0065] In this application, the "total volume of the spheres" is obtained by measuring the diameter d of each sphere and applying the formula V = (4 / 3)π(d / 2). 3 Calculate the volume of a single sphere, and sum the volumes of all the spheres to obtain the total volume of the sphere.

[0066] In this application, the "volume of the drum screen" is obtained by measuring the diameter d and length l of the drum screen, and then using the formula V = π(d / 2). 3 Calculate the volume of the drum screen.

[0067] In some embodiments, in step (2), the linear velocity of the drum screen is 0.1-5 m / s; optionally, the linear velocity of the drum screen is 0.5-3.5 m / s; optionally, the linear velocity of the drum screen is 1-2.5 m / s. In some embodiments, the linear velocity of the drum screen can be 0.1 m / s, 0.2 m / s, 0.3 m / s, 0.4 m / s, 0.5 m / s, 0.6 m / s, 0.7 m / s, 0.8 m / s, 0.9 m / s, 1.0 m / s, 1.1 m / s, 1.2 m / s, 1.3 m / s, 1.4 m / s, 1.5 m / s, 1.6 m / s, 1.7 m / s, 1.8 m / s, 1.9 m / s, 2.0 m / s, 2.1 m / s, 2 0.2m / s, 2.3m / s, 2.4m / s, 2.5m / s, 2.6m / s, 2.7m / s, 2.8m / s, 2.9m / s, 3.0m / s, 3.1m / s, 3.2m / s, 3.3m / s, 3.4m / s, 3.5m / s, 3.6m / s, 3.7m / s, 3.8m / s, 3.9m / s, 4.0m / s, 4.5m / s, 5m / s, or a range of any two of the above values ​​or values ​​within that range.

[0068] When the linear velocity of the drum screen is 0.5-3.5 m / s, the electrode sheet can be carried to a high altitude by the drum screen and then fall back down. It will not rotate with the drum screen under the action of centrifugal force, so as to achieve the purpose of turning and throwing the electrode sheet and active material in the drum screen, which is conducive to the separation of active material and aluminum foil, thereby achieving a higher powder yield, while controlling the aluminum content in the powder to be relatively low.

[0069] In some implementations, the duration of step (2) is 0.5 min to 40 min; optionally, the duration of step (2) is 1 min to 20 min; optionally, the duration of step (2) is 2 min to 10 min.

[0070] In some implementations, the duration of step (2) can be 0.5 min, 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, or a range of any two of the above values ​​or a value within that range.

[0071] In some embodiments, in step (3), the liquid includes one or more of deionized water and organic solvents; optionally, the liquid includes deionized water.

[0072] Organic solvents may include one or more of N-methylpyrrolidone (NMP), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC).

[0073] In some implementations, the liquid in step (3) is deionized water.

[0074] Choosing deionized water can reduce pollution and is more environmentally friendly.

[0075] In some embodiments, in step (3), the soaking time is 1-60 min; optionally, the soaking time is 3-30 min; optionally, the soaking time is 5-20 min.

[0076] Soaking for 1-60 minutes can improve efficiency, increase powder yield, and control the aluminum content in the powder to be low.

[0077] In some embodiments, the soaking time can be 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, or any range of two of the above values ​​or values ​​within that range.

[0078] In some embodiments, in step (3), the de-powdered positive electrode sheet is soaked in liquid and stirred.

[0079] Stirring and soaking can be done simultaneously or sequentially. For example, you can soak first and then stir; or stir first and then soak; or repeat the cycle of "soak first and then stir" or "stir first and then soak" once or more.

[0080] In some embodiments, in step (3), the stirring speed is 50-400 r / min; optionally, the stirring speed is 100-300 r / min; optionally, the stirring speed is 150-250 r / min.

[0081] Mixing can be carried out using any mixing equipment known to those skilled in the art, such as a mixer, mixing tank, or mixing vessel. In this application, "mixing speed" refers to the speed of the mixing shaft in the mixing equipment.

[0082] When the stirring speed is controlled at 50-400 r / min, the peeling force generated by the water flow rotation is relatively large, which is beneficial to the peeling of the active material and the current collector, and will not cause a large amount of damage to the aluminum foil or too much aluminum foil in the active material. This is conducive to improving the quality of subsequent products, thereby achieving a high powder yield, while controlling the aluminum content in the powder to be relatively low.

[0083] In some embodiments, the stirring speed can be 50 r / min, 60 r / min, 70 r / min, 80 r / min, 90 r / min, 100 r / min, 200 r / min, 300 r / min, 400 r / min, or a range of any two of the above values ​​or a value within that range.

[0084] In some implementations, the stirring time in step (3) is 1-60 min.

[0085] When the stirring time is controlled between 1 and 60 minutes, the active material and the current collector are separated more completely, without causing a large amount of damage to the aluminum foil or excessive aluminum foil in the active material. This is beneficial to the improvement of the quality of subsequent products, thereby achieving a higher powder yield while controlling the aluminum content in the powder to be relatively low.

[0086] In some embodiments, the stirring time can be 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, or any range of two of the above values ​​or values ​​within that range.

[0087] By soaking and stirring the positive electrode sheet, it is possible to separate >92% of the positive electrode active material from the current collector (e.g., aluminum foil), while the aluminum content in the powder is <300ppm.

[0088] In some embodiments, in step (3), the separated solid material is first filtered and then dried. In some embodiments, after filtration, the filter cake is washed with deionized water and then pressure filtered; this operation (washing and pressure filtration) is performed 1-4 times, optionally 1-2 times, optionally 3-4 times. In some embodiments, the moisture content of the solid material is 10-25% by weight before drying.

[0089] After repeated washing and filtration, large aluminum shavings generated during the stirring process can be effectively removed. The use of a filter press effectively removes free water from the positive electrode active material through mechanical means, resulting in lower energy consumption and lower cost in the subsequent drying process.

[0090] In some embodiments, drying can be carried out by various means / equipment known to those skilled in the art, including but not limited to one or more of flash dryers, drum dryers, mesh belt dryers, airflow dryers, and vacuum dryers.

[0091] Using flash dryers and / or airflow dryers results in high drying efficiency, short drying time, reduced floor space, shorter process time, reduced investment, and lower costs.

[0092] In some embodiments, the powder obtained after step (3) is collected, which includes positive electrode active material and a small amount of impurities (e.g., aluminum shavings), and further aluminum removal (including but not limited to mechanical vibration sieving) and demagnetization are performed to obtain positive electrode active material S2.

[0093] In some embodiments, the powder obtained in step (2) is combined with the powder obtained in step (3).

[0094] In some embodiments, the powder obtained in step (2) and the powder obtained in step (3) can be dealuminized (including but not limited to mechanical vibration sieving) and demagnetized separately, and then combined. Alternatively, they can be combined first and then dealuminized (including but not limited to mechanical vibration sieving) and demagnetized to finally obtain positive electrode active material S1+S2.

[0095] In some implementations, there are no restrictions on the order of aluminum removal and demagnetization. Aluminum can be removed first and then demagnetization, or demagnetization can be performed first and then aluminum removal, or aluminum can be removed first and then demagnetization and then aluminum removal, or demagnetization can be performed first and then aluminum removal and then demagnetization, and so on.

[0096] In some implementations, aluminum removal and demagnetization can be performed once or more.

[0097] During the crushing, drum screen de-powdering and mechanical stirring de-powdering processes, aluminum shavings and certain magnetic foreign objects are generated. After aluminum removal and demagnetization, the magnetic foreign objects and aluminum shavings in the material are effectively controlled, and each batch of material is uniform.

[0098] In some implementations, the positive electrode active materials S1+S2 are subjected to airflow pulverization, batch mixing, vibrating sieving, demagnetization and conveyed to the next process for lithium replenishment and regeneration.

[0099] In some embodiments, the aluminum foil and aluminum shavings recovered in the method are collected and briquetted.

[0100] Figure 1This application illustrates a method for recovering positive electrode active material according to one embodiment. After disassembling the electrode sheet, (1) the positive electrode sheet is placed in a bowl and calcined at high temperature to remove impurities (such as binders, conductive agents, etc.) other than the positive electrode active material from the positive electrode film layer, which is beneficial for subsequent de-powdering; (2) pre-de-powdering is then performed using a drum sieve, achieving separation of more than 60% of the positive electrode active material from the aluminum foil, collecting the powder (containing the positive electrode active material) and aluminum shavings separately; (3) the positive electrode sheet is then soaked and stirred, achieving separation of more than 92% of the positive electrode active material from the aluminum foil; (4) the aluminum foil and the mixture (containing the positive electrode active material and aluminum shavings) are collected separately; (5) the mixture is washed and filtered to obtain aluminum shavings and filtrate. The obtained filtrate is then pressure filtered and dried to obtain powder. The powder obtained in the above process is then subjected to aluminum removal and demagnetization before merging, or merged and then subjected to aluminum removal and demagnetization before finally obtaining the positive electrode active material. The aluminum shavings and aluminum foil obtained in the above process are further processed and then pressed into blocks.

[0101] Example

[0102] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0103] I. Preparation Method

[0104] Example 1

[0105] The waste battery cells are physically discharged, and the battery packs after full discharge are disassembled and sorted to separate the positive electrode sheets. The positive electrode sheets are broken into sheets with a long diameter of 1 mm and a short diameter of 1 mm, and placed into a 3 kg crucible. Then, they are placed in a roller furnace (air atmosphere) and calcined at a constant temperature of 500°C for 2 hours.

[0106] The calcined positive electrode sheet is poured into a drum sieve containing elastic balls with a diameter of 18 cm for de-powdering. The total volume of the elastic balls accounts for 35% of the volume of the drum sieve. The linear velocity of the drum sieve is 1.8 m / s. The sieving time in the drum sieve is 5 min. The material on the sieve and the material under the sieve, S1, are collected.

[0107] Soak the sieved material in deionized water for 10 minutes, then stir it for 5 minutes using a mixer (Shandong Baisheng Environmental Protection Technology Co., Ltd., BS-750) at a speed of 200 r / min.

[0108] The mixture obtained after soaking, stirring and de-powdering (containing positive electrode active material and aluminum shavings) is sieved (10 mesh) to remove aluminum shavings. Then, the filtrate is filtered using a filter press (Jingjin 120 plate and frame filter press) with 800 mesh filter cloth. After pressurizing the filter press, the water is discharged, and the positive electrode active material remains inside. The filter cake is washed with deionized water and then filtered again. The washing and filtration are repeated 3 times to finally obtain a filter cake with a water content of 18%.

[0109] The filter cake was dried using a flash dryer (Bopeng SZ145) with an inlet temperature of 350℃. The filter cake was evenly fed into the flash dryer via a screw feeder and dried in 3-5 seconds. The dried powder was then collected in a cyclone separator and a bag filter. The collected dried powder, along with the undersize material S1, was mechanically vibrated to remove aluminum. The vibrating screen had a diameter of 1m and a mesh size of 50. When the powder passed through the vibrating screen, aluminum shavings were collected as the oversize material. The undersize material was then removed from the magnetic material using a Korean Daebo electromagnetic separator to obtain the final positive electrode active material.

[0110] Example 2

[0111] The main difference between Example 2 and Example 1 is that the positive electrode sheet is broken into sheets with a long diameter of 1-30cm and a short diameter of 1-30cm.

[0112] Example 3

[0113] The main difference between Example 3 and Example 2 is that the diameter of the elastic ball is 1 cm.

[0114] Example 4

[0115] The main difference between Example 4 and Example 2 is that the diameter of the elastic ball is 30cm.

[0116] Example 5

[0117] The main difference between Example 5 and Example 2 is that the total volume of the elastic balls accounts for 70% of the volume of the drum screen.

[0118] Example 6

[0119] The main difference between Example 6 and Example 2 is that the total volume of the elastic balls accounts for 10% of the volume of the drum screen.

[0120] Example 7

[0121] The main difference between Example 7 and Example 2 is that the total volume of the elastic balls accounts for 80% of the volume of the drum screen.

[0122] Example 8

[0123] The main difference between Example 8 and Example 2 is that the total volume of the elastic balls accounts for 6% of the volume of the drum screen.

[0124] Example 9

[0125] The main difference between Example 9 and Example 2 is that the linear velocity of the drum screen is 3.5 m / s.

[0126] Example 10

[0127] The main difference between Example 10 and Example 2 is that the linear velocity of the drum screen is 0.5 m / s.

[0128] Example 11

[0129] The main difference between Example 11 and Example 2 is that the linear velocity of the drum screen is 5 m / s.

[0130] Example 12

[0131] The main difference between Example 12 and Example 2 is that the linear velocity of the drum screen is 0.2 m / s.

[0132] Example 13

[0133] The main difference between Example 13 and Example 2 is that the screening time in the drum screen is 40 minutes.

[0134] Example 14

[0135] The main difference between Example 14 and Example 2 is that the screening time in the drum screen is 0.5 min.

[0136] Example 15

[0137] The main difference between Example 15 and Example 2 is that the material on the sieve is soaked in NMP solution.

[0138] Example 16

[0139] The main difference between Example 16 and Example 2 is that the material on the sieve is soaked in deionized water for 60 minutes and then stirred at 50 r / min for 60 minutes.

[0140] Example 17

[0141] The main difference between Example 17 and Example 2 is that the material on the sieve is soaked in deionized water for 1 minute and then stirred at 400 r / min for 1 minute.

[0142] Example 18

[0143] The main difference between Example 18 and Example 2 is that Example 18 is calcined at a constant temperature of 300°C for 3.5 hours in a roller furnace (air atmosphere).

[0144] Example 19

[0145] The main difference between Example 19 and Example 2 is that Example 19 is fired at a constant temperature of 620°C for 0.5 hours in a roller furnace (air atmosphere).

[0146] Example 20

[0147] The main difference between Example 20 and Example 2 is that the bowls are stacked upright in a natural manner.

[0148] Comparative Example 1

[0149] The waste battery cells are physically discharged, and the battery packs after full discharge are disassembled and sorted to separate the positive electrode sheets. The positive electrode sheets are broken into sheets with a long diameter of 1-30cm and a short diameter of 1-30cm, and placed into a 3kg crucible. Then, they are placed in a roller furnace (air atmosphere) and calcined at a constant temperature of 500℃ for 2 hours.

[0150] The calcined positive electrode sheet was soaked in deionized water for 10 minutes, and then stirred for 5 minutes using a stirrer (Shandong Baisheng Environmental Protection Technology Co., Ltd., BS-750) with a stirring shaft speed of 200 r / min.

[0151] The mixture obtained after soaking, stirring and de-powdering (containing positive electrode active material and aluminum shavings) is sieved (10 mesh) to remove aluminum shavings. Then, the filtrate is filtered using a filter press (Jingjin 120 plate and frame filter press) with 800 mesh filter cloth. After pressurizing the filter press, the water is discharged, and the positive electrode active material remains inside. The filter cake is washed with deionized water and then filtered again. The washing and filtration are repeated 3 times to finally obtain a filter cake with a water content of 18%.

[0152] The filter cake was dried using a flash dryer (Bopeng SZ145) with an inlet temperature of 350℃. The filter cake was evenly fed into the flash dryer via a screw feeder and dried in 3-5 seconds. The dried powder was then collected in a cyclone separator and a bag filter. The collected dried powder was then mechanically vibrated to remove aluminum. The vibrating screen had a diameter of 1m and a mesh size of 50. Aluminum shavings were collected as the oversize material when the powder passed through the vibrating screen. The undersize material was then removed using a Korean Daebo electromagnetic separator to remove magnetic impurities, resulting in the final positive electrode active material.

[0153] Comparative Example 2

[0154] The waste battery cells are physically discharged, and the battery packs after full discharge are disassembled and sorted to separate the positive electrode sheets. The positive electrode sheets are broken into sheets with a long diameter of 1-30cm and a short diameter of 1-30cm, and placed into a 3kg crucible. Then, they are placed in a roller furnace (air atmosphere) and calcined at a constant temperature of 500℃ for 2 hours.

[0155] The calcined positive electrode sheet is poured into a drum sieve containing elastic balls with a diameter of 18 cm for de-powdering. The total volume of the elastic balls accounts for 35% of the volume of the drum sieve. The linear velocity of the drum sieve is 1.8 m / s. The sieving time in the drum sieve is 5 min. The material on the sieve and the material under the sieve, S1, are collected.

[0156] The undersize material S1 is mechanically vibrated to remove aluminum. The vibrating screen has a diameter of 1m and a screen mesh of 50 mesh. When the powder passes through the vibrating screen, aluminum chips are the oversize material. Then, the undersize material is removed from the magnetic foreign matter using a Korean Daebo electromagnetic separator to obtain the final positive electrode active material.

[0157] II. Testing Methods

[0158] 1. Determination of powder yield

[0159] Powder yield = final positive electrode active material mass / (initial mass of recycled electrode * (1 - current collector mass percentage in recycled electrode)), where the current collector mass percentage can be found in the relevant parameter table of recycled electrode.

[0160] 2. Determination of aluminum content

[0161] The aluminum content in the final positive electrode active material was determined by ICP testing.

[0162] III. Analysis of Test Results for Each Embodiment and Comparative Example

[0163] Each example and comparative example was prepared according to the above method, and various parameters were measured. The results are shown in Table 1 below.

[0164]

[0165] Based on the above, the recovery methods for the positive electrode active materials in Examples 1-20 all include the following steps:

[0166] (1) The positive electrode sheet is calcined to obtain the calcined positive electrode sheet;

[0167] (2) The calcined positive electrode sheet is de-powdered to obtain a de-powdered positive electrode sheet;

[0168] (3) Soak the de-powdered positive electrode sheet in liquid to separate the current collector and the positive electrode active material of the de-powdered positive electrode sheet, filter the liquid to obtain the positive electrode active material, and dry the positive electrode active material.

[0169] As can be seen from the comparison between Examples 1-20 and Comparative Examples 1-2, a higher powder yield can be achieved by using the method of this application.

[0170] As can be seen from the comparison between Examples 2-20 and Example 1, when the positive electrode has a major diameter of ≥1cm and a minor diameter of ≥1cm, it avoids the generation of more aluminum powder due to excessively fine grinding of the electrode and excessively small electrode size, thereby resulting in a lower aluminum content in the recovered powder.

[0171] As can be seen from the comparison between Examples 2, 5-6 and Examples 7-8, when the total volume of the spheres accounts for 10-70% of the volume of the drum screen, a high powder yield can be achieved while ensuring that the aluminum content in the powder is low.

[0172] A comparison of Examples 2, 9-10 and Examples 11-12 shows that a higher powder yield can be achieved when the linear velocity of the drum screen is 0.5-3.5 m / s.

[0173] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for recovering positive electrode active materials, characterized in that, The method includes the following steps: (1) The positive electrode sheet is calcined to obtain the calcined positive electrode sheet; (2) The calcined positive electrode sheet is de-powdered to obtain a de-powdered positive electrode sheet; (3) Soak the de-powdered positive electrode sheet in liquid to separate the current collector and the positive electrode active material of the de-powdered positive electrode sheet, filter the liquid to obtain the positive electrode active material, and dry the positive electrode active material.

2. The recycling method according to claim 1, characterized in that, The positive electrode has a major diameter of ≥1cm and a minor diameter of ≥1cm.

3. The recycling method according to claim 1 or 2, characterized in that, The calcined positive electrode sheet is de-powdered by mechanical separation.

4. The recycling method according to any one of claims 1-3, characterized in that, The calcined positive electrode sheet is de-powdered in a drum screen.

5. The recycling method according to any one of claims 1-4, characterized in that, The calcined positive electrode sheet is de-powdered in a drum sieve containing spherical objects.

6. The recycling method according to claim 5, characterized in that, The diameter of the sphere is 1-30cm; optionally, the diameter of the sphere is 5-25cm; optionally, the diameter of the sphere is 10-20cm.

7. The recycling method according to claim 5 or 6, characterized in that, The total volume of the spherical objects accounts for 5-80% of the volume of the drum screen; optionally, the total volume of the spherical objects accounts for 10-70% of the volume of the drum screen; optionally, the total volume of the spherical objects accounts for 20-50% of the volume of the drum screen.

8. The recycling method according to any one of claims 4-6, characterized in that, The linear velocity of the drum screen is 0.1-5 m / s; optionally, the linear velocity of the drum screen is 0.5-3.5 m / s; optionally, the linear velocity of the drum screen is 1-2.5 m / s.

9. The recycling method according to any one of claims 1-8, characterized in that, The duration of step (2) is 0.5 min to 40 min; optionally, the duration of step (2) is 1 min to 20 min; optionally, the duration of step (2) is 2 min to 10 min.

10. The recycling method according to any one of claims 1-9, characterized in that, In step (3), the liquid includes one or more of deionized water and organic solvents; optionally, the liquid includes deionized water.

11. The recycling method according to any one of claims 1-10, characterized in that, In step (3), the soaking time is 1-60 min; optionally, the soaking time is 3-30 min; optionally, the soaking time is 5-20 min.

12. The recycling method according to any one of claims 1-11, characterized in that, In step (3), the de-powdered positive electrode sheet is soaked in liquid and stirred.

13. The recycling method according to claim 12, characterized in that, The stirring speed is 50-400 r / min; optionally, the stirring speed is 100-300 r / min; optionally, the stirring speed is 150-250 r / min.

14. The recycling method according to claim 12 or 13, characterized in that, The stirring time is 1-60 min; optionally, the stirring time is 2-30 min; optionally, the stirring time is 3-20 min.

15. The recycling method according to any one of claims 1-14, characterized in that, In step (1), the calcination temperature is 300-620℃, optionally 400-600℃, optionally 450-550℃; the calcination time is 0.5-3.5h, optionally 1-3h, optionally 1.5-2.5h.

Images