Recycling method of lithium-rich manganese-based positive electrode material waste and positive electrode material

Abstract

The invention provides a recycling method of a lithium-rich manganese-based positive electrode material waste and a positive electrode material, and aims to prepare a high-performance lithium iron manganese phosphate positive electrode material from the lithium-rich manganese-based positive electrode material waste, realize efficient recycling of the lithium-rich manganese-based positive electrode material waste and greatly reduce the production cost of the lithium iron manganese phosphate positive electrode material.

Description

Technical Field

[0001] This application relates to the technical field of recycling and preparation of electrode materials, and particularly relates to a method for recycling waste rich lithium manganese-based cathode materials and a cathode material. Background Art

[0002] With the booming development of new energy vehicles and energy storage devices, the demand for lithium-ion batteries has increased sharply. The service life of commercially available lithium-ion batteries is generally 5 - 8 years. At present, a large number of lithium-ion batteries are retired every year and urgently need proper recycling and treatment. Whether from the perspective of environmental protection or economy, recycling and treating waste batteries and re-synthesizing the waste electrode materials therein into electrode materials are the best solutions. In this way, not only can a large number of waste batteries be processed in a short time, but also the production cost of electrode materials can be reduced, waste can be reduced, and ore mining can be decreased, which has great economic and social value.

[0003] Currently, the industry mainly focuses on the recycling of lithium iron phosphate-based and ternary cathode materials, lacking attention to rich lithium manganese-based cathode materials. With the development and application of rich lithium manganese-based cathode materials, the amount of materials and batteries to be recycled is increasing year by year. Therefore, there is an urgent need to provide a low-cost and efficient method for recycling and reusing rich lithium manganese-based cathode materials. Summary of the Invention

[0004] In view of this, the embodiments of this application provide a method for recycling waste rich lithium manganese-based cathode materials and a cathode material, aiming to prepare high-performance lithium iron phosphate-based cathode materials from waste rich lithium manganese-based cathode materials, realize the efficient recycling and reuse of waste rich lithium manganese-based cathode materials, and at the same time greatly reduce the production cost of lithium iron phosphate-based cathode materials.

[0005] The first aspect of the embodiments of this application provides a method for recycling waste rich lithium manganese-based cathode materials, including:

[0006] Recycling and preparing a cathode material using waste rich lithium manganese-based cathode materials, the cathode material including LiM x Fe 1-x PO4, where 0 < x < 1, and M includes Mn.

[0007] The applicant first proposed to use waste rich lithium manganese-based cathode materials as raw materials to recycle and prepare LiM x Fe 1-x PO4. This not only effectively solves the problem of recycling and utilization of waste rich lithium manganese-based cathode materials, protects the environment and saves mineral resources, but also can prepare LiM x Fe 1-x PO4 materials without adding additional lithium sources, greatly reducing the cost of LiM x Fe1-x The production cost of the PO4 material is of great economic value.

[0008] Optionally, the preparation of the cathode material by recycling the waste of the lithium-rich manganese-based cathode material includes the following steps:

[0009] (1) Placing the waste of the lithium-rich manganese-based cathode material in an acid solution for acidolysis to obtain a precursor solution; wherein, the waste of the lithium-rich manganese-based cathode material includes lithium element and transition metal elements, and the transition metal elements include Mn;

[0010] (2) Detecting the element content of the precursor solution, and then adding an iron source, a phosphorus source and a carbon source to the precursor solution according to the stoichiometric ratio of each element in the LiM x Fe 1-x PO4 to be prepared, and drying to obtain a cathode material precursor;

[0011] (3) Sintering the cathode material precursor under a protective atmosphere to obtain the cathode material.

[0012] Optionally, the molar ratio of the lithium element to the transition metal element in the waste of the lithium-rich manganese-based cathode material is greater than 1.

[0013] Optionally, the transition metal element further includes at least one of Ni, Co, V, Ti or Mo.

[0014] Optionally, the waste of the lithium-rich manganese-based cathode material includes aLi2MnO3·(1-a)LiM’O2, wherein 0 < a < 1, and M’ includes at least one of Ni, Co, V, Ti or Mo and Mn.

[0015] Optionally, it further includes adding a lithium source to the precursor solution according to the stoichiometric ratio of each element in the LiM x Fe 1-x PO4 to be prepared.

[0016] Optionally, the pH value of the acid solution ≤ 3.

[0017] Optionally, the acid solution includes at least one of hydrochloric acid, nitric acid, phosphoric acid or organic acid; wherein, the organic acid includes at least one of oxalic acid, acetic acid or acrylic acid.

[0018] Optionally, before the acidolysis, it further includes calcining the waste of the lithium-rich manganese-based cathode material in an air atmosphere.

[0019] The second aspect of the embodiments of the present application provides a cathode material, which is prepared according to the recycling method of the waste of the lithium-rich manganese-based cathode material provided in the first aspect of the embodiments of the present application. The above cathode material not only has low cost, but also has excellent electrochemical performance. Description of the Drawings

[0020] Figure 1 The process flow diagram of the recycling method for the waste of lithium-rich manganese-based cathode materials provided by an embodiment of the present application. Detailed Embodiments

[0021] Lithium-rich manganese-based cathode materials are expected to become the new generation of cathode materials for lithium-ion batteries due to their advantages such as high capacity and high voltage. This also means that a large amount of waste lithium-rich manganese-based cathode materials will appear in the future. How to efficiently and economically recycle the waste lithium-rich manganese-based cathode materials has become a difficult problem that needs to be overcome urgently. For this reason, the embodiments of the present application provide a recycling method for the waste of lithium-rich manganese-based cathode materials, aiming to directly transform the waste lithium-rich manganese-based cathode materials into high-performance cathode materials. The recycling method includes:

[0022] Recycling and preparing cathode materials by using the waste of lithium-rich manganese-based cathode materials. The cathode materials include LiM x Fe 1-x PO4, where 0 < x < 1, and M includes Mn.

[0023] The applicant first proposed to use the waste of lithium-rich manganese-based cathode materials as raw materials to recycle and prepare LiM x Fe 1-x PO4. It not only effectively solves the problem of recycling the waste of lithium-rich manganese-based cathode materials, protects the environment, saves mineral resources, but also can prepare LiM x Fe 1-x PO4 materials without adding additional lithium sources, greatly reducing the production cost of LiM x Fe 1-x PO4 materials, which has great economic value.

[0024] Please refer to Figure 1 , in some embodiments of the present application, the recycling and preparation of cathode materials by using the waste of lithium-rich manganese-based cathode materials includes the following steps:

[0025] S01. Placing the waste of lithium-rich manganese-based cathode materials in an acid solution for acidolysis to obtain a precursor solution; wherein, the waste of lithium-rich manganese-based cathode materials includes lithium elements and transition metal elements, and the transition metal elements include Mn;

[0026] S02. Detecting the element content of the above precursor solution, and then according to the LiM to be prepared x Fe 1-xAccording to the stoichiometric ratios of the elements in PO4, an iron source, a phosphorus source, and a carbon source are added to the above precursor solution, followed by drying to obtain a precursor of the cathode material; wherein, 0 < x < 1, and M includes Mn. In the embodiments of the present application, the element content in the precursor solution is determined according to the element composition of the lithium-rich manganese-based cathode material waste.

[0027] S03. Under a protective atmosphere, the above precursor of the cathode material is sintered to obtain a cathode material, and the above cathode material includes LiM x Fe 1-x PO4, wherein, 0 < x < 1, and M includes Mn.

[0028] It can be understood that during the charge and discharge cycles of the battery, lithium ions circulate reciprocally between the cathode and the anode: when the battery is charged, lithium ions are extracted from the cathode material and migrate to the anode; when the battery is discharged, lithium ions return from the anode to the cathode and intercalate into the cathode material. Thus, it can be understood that when the battery is fully discharged, the lithium ion content in the cathode material is the highest; when the state of charge (SOC) of the battery > 0, at least part of the cathode material is in a de-lithiated state, and at this time, when recycling the cathode material, part of the lithium will be lost. And the cathode material waste is obtained from the waste batteries that need to be disassembled. Therefore, whether from the perspective of production safety or economic value, generally, the waste batteries will be fully discharged before disassembly to obtain the cathode material waste. In particular, the molar ratio of lithium element to transition metal element in the fully discharged lithium-rich manganese-based cathode material waste is greater than 1. Therefore, LiM x Fe 1-x PO4 material can be prepared without additional lithium source. Also, in the bill of materials (BOM) for lithium iron phosphate-based materials, the cost of the lithium source usually accounts for more than 90%. Therefore, the above recycling method can not only realize the recycling of lithium-rich manganese-based cathode material waste, but also greatly reduce the production cost of LiM x Fe 1-x PO4. In step S01, under the action of the acid solution, lithium ions and manganese ions in the lithium-rich manganese-based cathode material waste are dissolved, and the molar ratio of lithium ions to manganese ions in the precursor solution is also correspondingly greater than 1. Thus, instead of adding an additional lithium source to the precursor solution, low-cost substances such as an iron source are supplemented to prepare a high-performance LiM x Fe 1-x PO4 material. And the above recycling method is simple and easy to operate, has strong process reliability, high production efficiency, and low cost, and can realize large-scale industrial production.

[0029] In the embodiments of the present application, the lithium-rich manganese-based cathode material waste may be derived from the modified lithium-rich manganese-based cathode material. At this time, the surface of the lithium-rich manganese-based cathode material waste may also have a carbon layer or a fast ion conductor coating layer. Alternatively, the lithium site and oxygen site of the lithium-rich manganese-based cathode material may also have doping elements, but these will not affect its recycling.

[0030] In some embodiments of the present application, in S01, when the lithium-rich manganese-based cathode material waste only contains lithium, manganese, and oxygen elements, it can be understood that the finally prepared cathode material is lithium iron manganese phosphate, that is, LiMn x Fe 1-x PO4, 0 < x < 1.

[0031] In some embodiments of the present application, other alkali metal elements (such as K, Na, etc.) are also doped at the lithium site of the lithium-rich manganese-based cathode material waste. When detecting the element content in the precursor solution, the molar amounts of the above alkali metal elements are also regarded as lithium elements for calculation, and, finally prepared LiMn x Fe 1-x PO4 is doped with alkali metal elements at the lithium site.

[0032] In some embodiments of the present application, in step S01, the transition metal elements in the lithium-rich manganese-based cathode material waste further include but are not limited to at least one of Ni, Co, V, Ti, or Mo, that is, the lithium-rich manganese-based cathode material waste itself contains the above transition metal element doping elements. It can be understood that the above doping elements will stably exist throughout the recycling process and will finally be doped as doping elements in the lithium iron manganese phosphate cathode material. For example, the finally prepared cathode material is LiMn 0.69 Ni 0.01 Fe 0.3 PO4.

[0033] In some embodiments of the present application, the lithium-rich manganese-based cathode material waste recovered from waste batteries includes aLi2MnO3·(1 - a)LiM’O2, where 0 < a < 1, and M’ includes at least one of Ni, Co, V, Ti, or Mo and Mn. At this time, a high-performance LiMn x Fe 1-x PO4 material can be prepared without adding a lithium source during the recycling process.

[0034] It can be understood that the positive electrode in the battery generally includes a current collector and a positive electrode active material layer disposed on the current collector, and the positive electrode active material layer contains positive electrode active materials (for example, lithium-rich manganese-based positive electrode materials, binders, and conductive agents). In some embodiments of the present application, step S01 also includes S11: disassembling the waste battery, taking out the positive electrode, and immersing the positive electrode in an organic solvent to remove the residual electrolyte in the positive electrode sheet, and separating the material of the positive electrode active material layer.

[0035] In the embodiments of the present application, the organic solvent may be selected from commonly used solvents for secondary battery electrolytes. In some embodiments of the present application, the organic solvent includes but is not limited to ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), propylene carbonate (PC), fluoroethylene carbonate (FEC), etc.

[0036] In some embodiments of the present application, in step S11, the waste battery is a fully discharged battery, and the molar ratio of lithium to transition metal elements (e.g., Mn, Ni, Co, etc.) in the lithium-rich manganese-based positive electrode material waste recovered from the waste battery is greater than 1. At this time, in step S02, it is not necessary to add a lithium source to the precursor solution to obtain LiM x Fe 1-x PO4, thus, LiM can be further reduced x Fe 1-x The preparation cost of PO4 positive electrode material is low and more environmentally friendly.

[0037] In some embodiments of the present application, step S01 also includes S12: calcining the material of the above-mentioned positive electrode active material layer under an air atmosphere to remove the binder and the conductive agent, and then immersing the calcined lithium-rich manganese-based positive electrode material waste in an acid solution for acid hydrolysis. In some specific embodiments of the present application, the insulation temperature during calcination under an air atmosphere in S12 is 200°C-500°C, and the insulation time is 3h-10h. Specifically, the above-mentioned insulation temperature may be, but is not limited to, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, etc. Specifically, the above-mentioned insulation time may be, but is not limited to, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, etc.

[0038] In some embodiments of the present application, in step S01, the above-mentioned acid hydrolysis specifically includes: soaking the lithium-rich manganese-based positive electrode material waste in an acid solution for 2h-10h. Exemplarily, the soaking time (that is, the acid hydrolysis time) can be but not limited to 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, etc. In some specific embodiments, the lithium-rich manganese-based positive electrode material waste is soaked in an acid solution at room temperature for 2h-10h. In other specific embodiments, the lithium-rich manganese-based positive electrode material waste is soaked in an acid solution under heating conditions for 2h-10h. In this way, it is beneficial to improve the acid hydrolysis efficiency. The specific temperature can be selected by ordinary technicians in this field according to the actual application needs and the type of acid solution.

[0039] In some embodiments of the present application, in step S01, the pH value of the acid solution is ≤ 3. In this way, a precursor solution containing lithium ions and transition metal ions can be obtained smoothly, reducing the loss of lithium source and transition metal source, and the acid solution with the above pH value is easily available in industry. Exemplarily, the pH value of the acid solution can be, but is not limited to, 1, 1.5, 2, 2.5, 3, 3.5, etc.

[0040] In some embodiments of the present application, in step S01, the acid solution is selected from at least one of hydrochloric acid, nitric acid, phosphoric acid or an organic acid; wherein the organic acid includes but is not limited to at least one of oxalic acid, acetic acid or acrylic acid.

[0041] In some embodiments of the present application, in step S01, the acid solution used for the acid hydrolysis treatment includes phosphoric acid. At this time, phosphorus elements introduced by phosphoric acid will exist in the precursor solution, and this part of phosphorus elements can be used as LiM x Fe 1-x PO4 is a phosphorus source. Therefore, in step S02, it is also necessary to determine the content of phosphorus in the precursor solution, and then determine the content of phosphorus according to the actual situation and the LiM to be prepared. x Fe 1-x The molar ratio of each element in PO4 determines the amount of phosphorus source added.

[0042] In some embodiments of the present application, in step S01, after the lithium-rich manganese-based cathode material waste is immersed in an acid solution for acid hydrolysis, the step further includes performing solid-liquid separation on the material obtained by acid hydrolysis to obtain a precursor solution. x Fe 1-x PO4, part of the phosphorus source can be replaced by an equal molar amount of other element sources, such as LiMn x Fe 1-x P 0.99 Si 0.01 O4. Those skilled in the art can make a selection according to practical applications.

[0043] In the embodiment of the present application, in step S02, an inductively coupled plasma atomic emission spectrometer (ICP-AES) is used to measure the content of lithium and transition metal elements in the precursor solution, and further obtain the molar ratio of lithium to transition metal elements.

[0044] In some embodiments of the present application, the phosphorus source includes but is not limited to one or more of phosphoric acid, ammonium dihydrogen phosphate, ammonium monohydrogen phosphate or lithium dihydrogen phosphate. It should be noted that lithium dihydrogen phosphate will also introduce an additional lithium source into the precursor solution, and ordinary technicians in this field need to select it according to actual production needs.

[0045] In some embodiments of the present application, in step S02, the iron source added to the precursor solution can be selected from the iron sources commonly used in lithium iron phosphate positive electrode materials, illustratively including but not limited to at least one of iron oxide, ferrous carbonate, ferrous oxalate, ferric chloride, ferrous nitrate or ferric acetate. The above iron sources are cheap and easy to obtain.

[0046] In some embodiments of the present application, in step S11, if incompletely discharged lithium-rich manganese-based cathode material waste is used, a lithium source may need to be added to the precursor solution in step S02. In some embodiments of the present application, the lithium source is at least one of but not limited to lithium acetate, lithium carbonate, lithium bicarbonate, lithium dihydrogen phosphate, lithium hydroxide or lithium oxalate.

[0047] In some embodiments of the present application, if in step S01, the manganese element is lost resulting in insufficient manganese content, or the transition metal element is lost resulting in LiM x Fe 1-x If the raw material of the transition metal element at the M position in PO4 is insufficient, a manganese source, or at least one of a manganese source, a nickel source, and a cobalt source may be added to the precursor solution. In some specific embodiments, the manganese source includes but is not limited to at least one of manganese carbonate, manganese oxalate, manganese sulfate, manganese nitrate, manganese chloride, or manganese acetate.

[0048] In some embodiments of the present application, in step S02, the carbon source includes but is not limited to at least one of glucose, sucrose, citric acid, conductive carbon black, carbon nanotubes or graphene. The above carbon source can not only serve as a reducing agent, but also reduce the high-valent metal ions in the precursor material (for example, Fe 3+ Reduction to Fe 2+ ), a carbon coating layer may also be formed on the surface of the finally prepared positive electrode material. That is, in some embodiments, the surface of the positive electrode material has a carbon coating layer.

[0049] In some embodiments of the present application, the amount of carbon source added can be determined according to the required thickness of the carbon coating layer.

[0050] In some embodiments of the present application, the drying in step S02 may be spray drying.

[0051] In some embodiments of the present application, in step S03, the sintering condition under the protective atmosphere is calcining at 600°C-800°C for 3h-15h. The sintering temperature may be, but not limited to, 600°C, 650°C, 700°C, 750°C, 800°C, etc., and the sintering time may be, but not limited to, 3h, 5h, 8h, 10h, 12h, 15h, etc. In some specific embodiments of the present application, the protective atmosphere may be nitrogen or argon.

[0052] In some embodiments of the present application, the method for recycling waste lithium-rich manganese-based positive electrode materials includes step S01, step S02 and step S03:

[0053] Among them, S01 includes S11-S13, specifically:

[0054] S11, dismantling the fully discharged waste batteries containing lithium-rich manganese-based positive electrode materials, taking out the positive electrode, and immersing the positive electrode in an organic solvent to remove the residual electrolyte in the positive electrode sheet, and separating the material of the positive electrode active material layer.

[0055] S12, calcining the obtained material of the positive electrode active material layer under air atmosphere;

[0056] S13, soaking the material calcined in step S12 in an acid solution to obtain a precursor solution;

[0057] S02: Detect the element content of the precursor solution, and then x Fe 1-x The stoichiometric ratio of each element in PO4 is added to the precursor solution, and then dried to obtain a cathode material precursor;

[0058] S03: Sintering the positive electrode material precursor under a protective atmosphere to obtain a positive electrode material, wherein the positive electrode material includes LiM x Fe 1-x PO4.

[0059] The embodiment of the present application also provides a positive electrode material, which is prepared by the recycling method of the aforementioned lithium-rich manganese-based positive electrode material waste provided in the embodiment of the present application.

[0060] The above-mentioned positive electrode material is not only low in cost but also has excellent electrochemical performance.

[0061] The technical solution of the present application is described below in conjunction with Example 1.

[0062] Example 1

[0063] Disassemble the lithium-rich manganese-based waste batteries to obtain a positive electrode active material layer mixed with 0.4Li2MnO3·0.6LiMnO2, and calcine it in an air atmosphere to obtain Li 1.4 MnO 2.4 , namely LiMn 0.71 O 1.71 , and soak it in an acid solution (specifically dilute nitric acid with a pH of 1) at room temperature for acid hydrolysis for 10 hours to obtain a precursor solution; wherein the molar ratio of lithium ions to manganese ions in the precursor solution is 1:0.71, and then the precursor solution is supplemented with an iron source (specifically Fe2O3), a phosphorus source (specifically H3PO4) and a carbon source (specifically glucose), wherein 0.29 mol of iron and 1 mol of phosphorus are supplemented for every 1 mol of lithium ions, and then dried to obtain a positive electrode material precursor, and the positive electrode material precursor is sintered in a nitrogen atmosphere to obtain a positive electrode material LiFe 0.29 Mn 0.71 PO4.

[0064] In order to highlight the beneficial effects of the embodiments of the present application, the following comparative examples are provided.

[0065] Comparative Example 1

[0066] According to the existing technology, lithium iron phosphate materials are recycled from waste lithium iron phosphate batteries to prepare LiFe 0.29 Mn 0.71 PO4.

[0067] Comparative Example 2

[0068] According to the existing technology, the lithium manganese oxide material in the waste lithium manganese oxide battery is recycled to prepare LiFe 0.29 Mn 0.71 PO4.

[0069] Comparative Example 3

[0070] According to the existing technology, an iron source, a lithium source (specifically lithium carbonate), a manganese source, a phosphorus source and a carbon source are mixed to synthesize LiFe 0.29 Mn 0.71 PO4.

[0071] The recycling prices of used batteries are summarized in Table 1. 0.29 Mn 0.71The cost of PO4 is summarized in Table 1. Understandably, market prices fluctuate, and the calculation is based on the current market prices. Among them, the price of lithium source is 200 yuan / kg, the average price of iron source is 2 yuan / kg, the average price of manganese source is 5 yuan / kg, the price of phosphorus source is 10 yuan / kg, and the price of carbon source is 1 yuan / kg.

[0072] Table 1

[0073]

[0074]

[0075] It can be seen from Table 1 that the method for recycling lithium-rich manganese-based cathode material waste provided in the embodiment of the present application can greatly reduce the production cost of lithium iron manganese phosphate materials.

[0076] The above is an exemplary embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made thereto without departing from the principles of the present application. These improvements and modifications are also considered to be within the scope of protection of the present application.

Claims

1. A method for recycling waste lithium-rich manganese-based positive electrode materials, characterized in that: Including: Recycling and preparing a cathode material from waste of a lithium-rich manganese-based cathode material, the cathode material comprising LiM x Fe 1-x PO4, where 0 < x < 1 and M comprises Mn.

2. The recycling method according to claim 1, characterized in that: The preparation of the cathode material by recycling the waste of the lithium-rich manganese-based cathode material includes the following steps: Placing the waste of the lithium-rich manganese-based cathode material in an acid solution for acidolysis to obtain a precursor solution; wherein, the waste of the lithium-rich manganese-based cathode material includes lithium elements and transition metal elements, and the transition metal elements include Mn; Detect the element content of the precursor solution, and then x Fe 1-x The stoichiometric ratio of each element in PO4 is added to the precursor solution, and then dried to obtain a cathode material precursor; Sintering the cathode material precursor under a protective atmosphere to obtain the cathode material.

3. The recycling method according to claim 2, characterized in that: The molar ratio of the lithium element to the transition metal element in the waste of the lithium-rich manganese-based cathode material is greater than 1.

4. The recycling method according to any one of claims 2 to 3, characterized in that: The transition metal element further includes at least one of Ni, Co, V, Ti or Mo.

5. The recycling method according to any one of claims 1 to 4, characterized in that: The waste of the lithium-rich manganese-based cathode material includes aLi2MnO3·(1-a)LiM’O2, where 0 < a < 1, and M’ includes at least one of Ni, Co, V, Ti or Mo and Mn.

6. The recycling method according to any one of claims 2 to 5, characterized in that: Also included is the LiM to be prepared x Fe 1-x The stoichiometric ratio of each element in PO4, and a lithium source are added to the precursor solution.

7. The recycling method according to any one of claims 2 to 6, characterized in that: The pH value of the acid solution ≤ 3.

8. The recycling method according to claim 7, characterized in that: The acid solution includes at least one of hydrochloric acid, nitric acid, phosphoric acid or organic acid; wherein, the organic acid includes at least one of oxalic acid, acetic acid or acrylic acid.

9. The recycling method according to any one of claims 2 to 8, characterized in that: Before the acidolysis, it further includes calcining the waste of the lithium-rich manganese-based cathode material in an air atmosphere.

10. A positive electrode material, characterized in that: The cathode material is obtained by the recycling method of the waste of the lithium-rich manganese-based cathode material according to any one of claims 1-9.

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