Positive electrode material and preparation method thereof, and battery and preparation method thereof

Abstract

The invention relates to a positive electrode material and a preparation method thereof, and a battery and a preparation method thereof. The preparation method of the positive electrode material comprises the following steps: acquiring a general ingredient ratio of the positive electrode material in a battery to be prepared, and acquiring a repaired and recycled positive electrode material; determining the proportion range of a target inactive substance in the positive electrode material according to the general ingredient ratio; the upper limit value of the ratio range is smaller than the general ratio of the target inactive substance in the general ingredient ratio; and preparing the target inactive substance for the repaired and recycled positive electrode material according to the proportion range to obtain a newly prepared positive electrode material. By adopting the method, the proportion of auxiliary materials such as positive electrode inactive substances can be reduced, the proportion of main materials such as positive electrode active substances can be improved, the preparation cost is reduced, and the battery performance can be improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a positive electrode material and a preparation method thereof, a battery and a preparation method thereof. Background Art

[0002] With the development of new energy technologies, lithium-ion batteries are being used more and more widely.

[0003] Lithium-ion batteries mainly include positive electrode sheets, electrolytes, separators and negative electrode sheets. Among them, the positive electrode materials in the positive electrode sheets include positive electrode active substances and positive electrode inactive substances. The positive electrode active substances are the core components of lithium-ion batteries and are responsible for the occurrence of electrochemical reactions; while the positive electrode inactive substances are auxiliary materials that exist to optimize the electrode structure, improve performance and ensure long-term stability; the two work together to ensure the efficient operation and long life of the battery.

[0004] At present, the preparation cost of positive electrode materials is relatively high. Therefore, how to effectively reduce the preparation cost of positive electrode materials has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] Based on this, it is necessary to provide a positive electrode material and a preparation method thereof, a battery and a preparation method thereof that can reduce the preparation cost in order to address the above technical problems.

[0006] In a first aspect, the present application provides a method for preparing a positive electrode material, the method comprising:

[0007] Obtaining the general proportion of positive electrode materials in the battery to be prepared, and obtaining the positive electrode materials for repair and recycling;

[0008] Determining a proportion range of the target inactive substance in the positive electrode material according to the general proportion; an upper limit value of the proportion range is less than a general proportion value of the target inactive substance in the general proportion;

[0009] The target inactive substance is formulated into the repaired and recovered positive electrode material according to the proportion range to obtain a newly prepared positive electrode material.

[0010] In one embodiment, determining the proportion range of the target inactive substance in the positive electrode material according to the general ingredient ratio includes:

[0011] Determining a reduction range of the proportion of the target inactive substance according to the general proportion value of the target inactive substance in the general ingredient ratio;

[0012] The proportion range of the target inactive substance is determined according to the general proportion value and the proportion reduction range.

[0013] In one embodiment, determining the reduction range of the proportion of the target inactive substance according to the general proportion value of the target inactive substance in the general ingredient ratio includes:

[0014] Obtaining a preset lower limit value of the proportion reduction of the target inactive substance;

[0015] The range between the lower limit value of the proportion reduction and the general proportion value is determined as the proportion reduction range.

[0016] In one embodiment, determining the proportion range of the target inactive substance according to the general proportion value and the proportion reduction range includes:

[0017] Determine the difference between the general proportion value and the lower limit value of the proportion reduction range as the upper limit value of the proportion range;

[0018] The difference between the general proportion value and the upper limit value of the proportion reduction range is determined as the lower limit value of the proportion range.

[0019] In one embodiment, the target inactive substance includes at least one of a conductive agent and a binder, wherein the maximum value of the proportion range of the conductive agent is smaller than the general proportion value of the conductive agent in the general ingredient ratio, and the maximum value of the proportion range of the binder is smaller than the general proportion value of the binder in the general ingredient ratio.

[0020] In one embodiment, the step of obtaining the general proportion of the positive electrode material in the battery to be prepared includes:

[0021] Obtaining the battery type of the battery to be prepared;

[0022] The general proportion of the positive electrode material is obtained according to the battery type.

[0023] In one embodiment, the step of obtaining the repaired and recycled positive electrode material comprises:

[0024] Pre-treating waste materials to obtain positive electrode fragments; the waste materials include positive electrode materials;

[0025] placing the positive electrode fragments in an aqueous solution to obtain separated positive electrode materials;

[0026] The separated positive electrode material is dried and crushed to obtain the repaired and recovered positive electrode material.

[0027] In a second aspect, the present application provides a positive electrode material obtained by the positive electrode material preparation method as described above.

[0028] In a third aspect, the present application provides a method for preparing a battery, the method comprising:

[0029] Obtaining a positive electrode material using the positive electrode material preparation method as described above;

[0030] Mixing the positive electrode material and a solvent to obtain a positive electrode slurry;

[0031] Applying the positive electrode slurry on one side of the positive electrode current collector;

[0032] Drying the positive electrode current collector coated with the positive electrode slurry to obtain a positive electrode sheet;

[0033] The positive electrode sheet, the negative electrode sheet, the separator and the electrolyte are assembled to obtain a battery.

[0034] In a fourth aspect, the present application provides a battery obtained by the battery preparation method as described above.

[0035] The above-mentioned positive electrode material and preparation method thereof, battery and preparation method thereof, obtain the general ingredient ratio of the positive electrode material in the battery to be prepared, and obtain the repaired and recovered positive electrode material, determine the proportion range of the target inactive substance in the positive electrode material according to the general ingredient ratio, and prepare the target inactive substance for the repaired and recovered positive electrode material according to the proportion range to obtain a newly prepared positive electrode material; the method uses the repaired and recovered positive electrode material to re-formulate the newly prepared positive electrode material, which can be used to prepare batteries, realizes the repair, recovery and reuse of the positive electrode material, and reduces the preparation cost; in addition, because the target inactive substance in the repaired and recovered positive electrode material is active or well preserved, it is convenient for the subsequent preparation The process provides a prerequisite for reducing the proportion of target inactive substances to reduce the preparation cost; based on this, since the upper limit value of the proportion range of the target inactive substances is smaller than the general proportion value of the target inactive substances in the general ingredient ratio, therefore, in the newly prepared positive electrode material obtained according to the proportion range of the target inactive substances, the actual proportion value of the target inactive substances is smaller than the general proportion value in the general ingredient ratio, that is, preparing the positive electrode material according to the proportion range of the target inactive substances can reduce the proportion of auxiliary materials such as positive electrode inactive substances, thereby increasing the proportion of main materials such as positive electrode active substances, further reducing the preparation cost, and helping to improve battery performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic flow chart of a method for preparing a positive electrode material in one embodiment;

[0037] Figure 2 is a schematic flow chart of a method for preparing a positive electrode material in one embodiment;

[0038] Figure 3 is a schematic flow chart of a method for preparing a positive electrode material in yet another embodiment;

[0039] Figure 4 A schematic diagram of a process for preparing a positive electrode material in another embodiment;

[0040] Figure 5 is a schematic flow chart of a method for preparing a positive electrode material in another embodiment;

[0041] Figure 6 is a schematic diagram of a process for preparing a battery in one embodiment;

[0042] Figure 7 is a schematic diagram of the structure of a battery in one embodiment;

[0043] Figure 8 is a schematic flow chart of a method for preparing a battery in another embodiment;

[0044] Fig. 9 A schematic diagram of a scanning electron microscope showing a positive electrode material repaired and recovered in one embodiment;

[0045] Fig.10 A schematic diagram of a scanning electron microscope showing a positive electrode material that has been repaired and recovered in another embodiment;

[0046] Fig.11 A scanning electron microscope schematic diagram of the repaired and recycled positive electrode material in yet another embodiment. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0048] With the rapid development of modern electronic devices (such as smartphones, laptops, etc.) and the electric vehicle industry, the performance requirements for lithium-ion batteries are increasing. As a key component of lithium-ion batteries, cathode materials have a vital impact on battery capacity, cycle life, rate performance and safety. The quality of their performance directly affects the user experience and development prospects of related products. The composition and preparation process of cathode materials are the key factors that determine their performance.

[0049] As mentioned in the background technology, the preparation cost of battery positive electrode materials in the related technology is relatively high. In this regard, the present application provides a positive electrode material and a preparation method thereof, a battery and a preparation method thereof, which can reduce the proportion of inactive substances in the positive electrode and increase the proportion of active substances in the positive electrode, thereby reducing the preparation cost and helping to improve the performance of the battery.

[0050] In one embodiment, Figure 1As shown, a method for preparing a positive electrode material is provided, and the method includes the following steps S102 to S106.

[0051] S102: Obtain the general proportion of the positive electrode material in the battery to be prepared, and obtain the repaired and recycled positive electrode material.

[0052] The battery to be prepared refers to a battery prepared using a positive electrode material, such as a lithium-ion battery. The positive electrode material includes a positive electrode active material and a positive electrode inactive material. Among them, the positive electrode active material is the core component of the lithium-ion battery and is used to store and release energy. The battery performance is closely related to the positive electrode active material, for example, battery capacity, energy density, cycle life or other performance indicators.

[0053] The positive electrode active material may be any suitable material. For example, the positive electrode active material may include at least one of lithium iron phosphate (LiFePO4, LFP), nickel manganese cobalt oxide (NMC), nickel cobalt aluminum oxide (NCA), lithium cobalt oxide (LCO), lithium cobalt oxide, lithium manganese oxide, nickel cobalt manganese oxide, nickel cobalt aluminum oxide and other types of materials. Specifically, a suitable material can be selected as the positive electrode active material according to the preparation requirements, and there is no limitation here.

[0054] Positive electrode inactive materials are auxiliary materials that do not directly participate in electrochemical reactions. Positive electrode inactive materials are intended to improve battery performance, for example, to optimize electrode structure, improve battery stability, etc. Positive electrode inactive materials may include conductive agents and binders.

[0055] The ingredient ratio is used to indicate the ratio of various substances in the positive electrode material. The ingredient ratio includes the weight ratio or mass ratio of the positive electrode active material to the positive electrode inactive material. Taking the positive electrode inactive material including a binder and a conductive agent as an example, the ingredient ratio may include the ratio of the positive electrode active material, the binder and the conductive agent. The general ingredient ratio can be understood as the general or commonly used ingredient ratio of the positive electrode material in the battery manufacturing industry, and can also be understood as the ingredient ratio of the positive electrode material pre-set according to the battery preparation requirements. For example, the general ingredient ratio of the positive electrode active material such as LFP, the binder such as PDVF and the conductive agent such as SP in the battery to be prepared is 90:5:5. This is only an exemplary explanation, and the specific value of the general ingredient ratio can be determined according to the actual application scenario, and it is not too limited here.

[0056] Repaired and recycled positive electrode materials refer to positive electrode materials recovered by repairing and treating waste materials. Repaired and recycled positive electrode materials include repaired and recycled positive electrode active materials and repaired and recycled positive electrode inactive materials. Among them, the repaired and recycled positive electrode inactive materials include at least one of repaired and recycled binders and repaired and recycled conductive agents. Among them, the positive electrode inactive materials in the repaired and recycled positive electrode materials are active and well preserved.

[0057] S104: determining a proportion range of the target inactive substance in the positive electrode material according to the general proportion; an upper limit value of the proportion range is less than a general proportion value of the target inactive substance in the general proportion.

[0058] The target inactive substance is any one or more of the positive electrode inactive substances. Exemplarily, the target inactive substance includes at least one of a binder and a conductive agent. Among them, the binder is an inactive substance used to enhance the binding between the components in the positive electrode material. The binder can firmly bind the positive electrode active material, the conductive agent and other components together, and ensure that these materials can be stably attached to the positive electrode current collector. The binder helps maintain the integrity of the electrode structure. The binder may include at least one suitable material, for example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene, sodium carboxymethyl cellulose or other types of materials, which are not limited here.

[0059] Conductive agent is an inactive substance used to improve electronic conductivity. Conductive agent can ensure that the battery current can be evenly distributed throughout the electrode, thereby improving the overall performance of the battery, including charge and discharge efficiency, power density and cycle life. Conductive agent can include at least one suitable material, such as conductive carbon black (Super P, SP), graphite, carbon nanotubes, graphene, conductive polymers or other types of materials, which are not limited here.

[0060] The proportion range of the target inactive substance refers to the proportion range of the target inactive substance in the positive electrode material to be prepared (i.e., the newly prepared positive electrode material in the subsequent step S106). Among them, the upper limit value of the proportion range can be understood as the maximum value of the proportion range. The general proportion value of the target inactive substance refers to the proportion value of the target inactive substance in the general proportion. Among them, the upper limit value of the proportion range of the target inactive substance is less than the general proportion value of the target inactive substance in the general proportion. Exemplarily, the target inactive substance includes a binder and a conductive agent, then the upper limit value of the proportion range of the binder is less than the general proportion value of the binder in the general proportion, and the upper limit value of the proportion range of the conductive agent is less than the general proportion value of the conductive agent in the general proportion.

[0061] Taking the general proportion of the positive electrode active material such as LFP, the binder such as PVDF and the conductive agent such as SP in the aforementioned battery to be prepared as 90:5:5 as an example, the general proportion of the binder is 5%, and the general proportion of the conductive agent is 5%. If the target inactive material includes a binder, the upper limit of the binder proportion range is less than 5%, for example, the upper limit is 4.9%, 4.99%, 4.999% or other suitable values, which are only illustrative here and are not overly limited. The proportion in this application can be understood as weight proportion or mass proportion.

[0062] S106: preparing a target inactive substance for the repaired and recovered positive electrode material according to a proportion range to obtain a newly prepared positive electrode material.

[0063] Exemplarily, the actual proportion of the newly prepared positive electrode material is determined according to the proportion range of the target inactive substance, wherein the actual proportion includes the actual proportions of the positive electrode active substance and the positive electrode inactive substance, the actual proportions of the positive electrode inactive substance include the actual proportions of the target inactive substance, and the actual proportions of the target inactive substance are within the proportion range of the target inactive substance.

[0064] The newly prepared positive electrode material at least includes the repaired and recycled positive electrode material. Wherein, when the actual proportion of the target inactive substance is not zero, the newly prepared positive electrode material includes the repaired and recycled positive electrode material and the formulated and added target inactive substance.

[0065] It should be noted that, when the positive electrode inactive material includes the target inactive material, and the positive electrode inactive material also includes other inactive materials, the other inactive materials can be formulated into the repaired and recovered positive electrode material according to the general proportion of the other inactive materials in the general proportion, to obtain a newly prepared positive electrode material. For example, taking the general proportion of 90:5:5 of the positive electrode material to be prepared for the battery including the positive electrode inactive material such as LPF, the binder such as PVDF and the conductive agent such as SP as the target inactive material includes the binder PVDF, for example, the proportion of the binder ranges from 0 to 4.99%, wherein the general proportion of the conductive agent is 5%, based on this, the binder and the conductive agent can be formulated into the repaired and recovered positive electrode material to obtain a newly prepared positive electrode material.

[0066] The method for preparing the positive electrode material provided in the embodiment of the present application obtains the general ingredient ratio of the positive electrode material in the battery to be prepared, and obtains the repaired and recovered positive electrode material, determines the proportion range of the target inactive substance in the positive electrode material according to the general ingredient ratio, and prepares the target inactive substance for the repaired and recovered positive electrode material according to the proportion range to obtain a newly prepared positive electrode material; the method uses the repaired and recovered positive electrode material to re-formulate the newly prepared positive electrode material, which can be used to prepare the battery, realizes the repair, recovery and reuse of the positive electrode material, and reduces the preparation cost; in addition, because the target inactive substance in the repaired and recovered positive electrode material is active or well preserved, it is convenient for the subsequent preparation of the positive electrode material. The process provides a prerequisite for reducing the proportion of target inactive substances in order to reduce the preparation cost; based on this, since the upper limit value of the proportion range of the target inactive substances is smaller than the general proportion value of the target inactive substances in the general proportion, therefore, in the newly prepared positive electrode material obtained according to the proportion range of the target inactive substances, the actual proportion value of the target inactive substances is smaller than the general proportion value in the general proportion, that is, the positive electrode material is prepared according to the proportion range of the target inactive substances, compared with the preparation according to the general proportion, the proportion of auxiliary materials such as the target inactive substances is reduced, thereby increasing the proportion of main materials such as the positive electrode active substances, further reducing the preparation cost, and helping to improve the battery performance.

[0067] In one embodiment, Figure 2 As shown, step S104, determining the proportion range of the target inactive substance in the positive electrode material according to the general ingredient ratio, includes the following steps S202 and S204.

[0068] S202: Determine a reduction range of the proportion of the target inactive substance according to the general proportion value of the target inactive substance in the general ingredient ratio.

[0069] The reduced proportion range refers to the reduced proportion range of the target inactive substance compared to the general proportion value in the general ingredient ratio, or the reduced range.

[0070] Exemplarily, according to the general proportion value of the target inactive substance in the general ingredient ratio, the proportion reduction range of the target inactive substance is determined according to the preset rules. Among them, the preset rules are used to represent the rules for calculating the proportion reduction range according to the general proportion value of the target inactive substance. The preset rules can be pre-set and are not specifically limited here. For example, the proportion reduction range can be determined according to the preset proportion reduction lower limit value and the general proportion value, as described below for details.

[0071] S204: Determine a proportion range of the target inactive substance according to the general proportion value and the proportion reduction range.

[0072] Exemplarily, the difference between the general proportion value and the upper limit value of the proportion reduction range can be determined as the lower limit value of the proportion range of the target inactive substance, and the difference between the general proportion value and the lower limit value of the proportion reduction range can be determined as the upper limit value of the proportion range of the target inactive substance.

[0073] For example, the general proportion of the target inactive material including the conductive agent such as SP is 1.5%, and the proportion of the conductive agent is reduced in the range of 0.01% to 1.5%, so the proportion of the conductive agent ranges from 0 to 1.49%.

[0074] The method for preparing the positive electrode material provided in the embodiment of the present application determines the range of reduction of the proportion of the target inactive substance according to the general proportion value of the target inactive substance in the general ingredient ratio, and determines the range of the proportion of the target inactive substance according to the general proportion value and the range of reduction of the proportion. In this way, the positive electrode material prepared according to the proportion range has a reduced amount of the target inactive substance within the range of reduction of the proportion, compared with the positive electrode material prepared according to the general proportion value, which reduces the preparation cost and realizes the effective adjustment of the proportion of each component in the positive electrode material, which helps to improve the performance of the battery prepared subsequently.

[0075] In one embodiment, Figure 3 As shown, step S202, according to the general proportion value of the target inactive substance in the general ingredient ratio, determines the reduction range of the proportion of the target inactive substance, including the following steps S302 and S304.

[0076] S302: Obtaining a preset lower limit value of the percentage reduction of the target inactive substance.

[0077] The lower limit of the reduction in the proportion of the target inactive substance is preset and can be set accordingly based on experiments, experience or application requirements such as cost, etc., and is not limited here. The lower limit of the reduction in proportion is greater than 0 and is less than the general proportion of the target inactive substance in the general ingredient ratio. For example, the lower limit of the reduction in proportion can be 0.01%, 0.01%, 0.1%, 0.5%, 1% or other suitable values, which are not specifically limited here.

[0078] It should be noted that the lower limits of the proportion of different positive electrode inactive substances may be the same or different. For example, the lower limits of the proportion of the binder and the conductive agent are the same and are 0.01%; for another example, the lower limits of the proportion of the binder and the conductive agent are different, and the lower limit of the proportion of the binder is 0.01%, and the lower limit of the proportion of the conductive agent is 0.05%; the above is only an exemplary description and is not limited here.

[0079] S304: Determine a range between the lower limit value of the proportion reduction and the general proportion value as a proportion reduction range.

[0080] The lower limit of the percentage reduction is used as the lower limit of the percentage reduction range, and the general percentage value is used as the upper limit of the percentage reduction range. For example, if the conductive agent is the target inactive substance, its lower limit of the percentage reduction is 0.01%, and the general percentage value is 5%, then the percentage reduction range is 0.01%~5%.

[0081] The method for preparing the positive electrode material provided in the embodiment of the present application obtains the preset lower limit value of the proportion reduction of the target inactive substance, and determines the range between the lower limit value of the proportion reduction and the general proportion value as the proportion reduction range. In this way, the proportion reduction range can be accurately obtained based on the lower limit value of the proportion reduction and the general proportion value, so that the proportion range of the target inactive substance in the newly prepared positive electrode material can be determined according to the proportion reduction range, thereby achieving the reduction treatment of the target inactive substance, increasing the main material proportion of the positive electrode active substance in the positive electrode material, and helping to improve the battery performance.

[0082] In one embodiment, Figure 4 As shown, step S102, obtaining the general proportion of the positive electrode material in the battery to be prepared, includes the following steps S402 and S404.

[0083] S402: Obtain the battery type of the battery to be prepared.

[0084] Battery types include but are not limited to button batteries, soft-pack batteries, square-shell batteries, cylindrical batteries or other types of lithium-ion batteries.

[0085] S404: Obtain a general proportion of positive electrode materials according to the battery type.

[0086] In the application, an association library can be pre-stored, which includes the association relationship between various battery types and the corresponding universal ingredient ratios of positive electrode materials. After obtaining the battery type of the battery to be prepared, the association library can be queried according to the battery type to determine the corresponding universal ingredient ratio of the positive electrode material.

[0087] It should be noted that the general proportion of the positive electrode materials of different battery types to be prepared may be the same or different, and can be set according to actual preparation requirements, which is not limited here. For example, the general proportion of the positive electrode active material such as LFP, the binder such as PVDF and the conductive agent such as SP in button batteries is 90:5:5; the general proportion of the positive electrode active material such as LFP, the binder such as PVDF and the conductive agent such as SP in non-button batteries such as soft-pack batteries, square-shell batteries and cylindrical batteries is 96.5:2:1.5.

[0088] In an embodiment of the present application, by obtaining the battery type of the battery to be prepared, and obtaining the universal ingredient ratio of the positive electrode material according to the battery type, the target inactive substance in the positive electrode material is reduced based on the universal ingredient ratio of the positive electrode material of the battery to be prepared, and the target inactive substance is formulated for the repaired and recovered positive electrode material according to the proportion range obtained after the reduction. Not only can the positive electrode material that meets the ingredient requirements of the battery to be prepared be obtained, but also the proportion of two types of auxiliary materials such as conductive agents and / or binders of the positive electrode inactive substances can be reduced, thereby increasing the proportion of the main material of the positive electrode active substance, and then improving the battery performance.

[0089] It can be understood that positive electrode materials such as lithium iron phosphate materials have the advantages of high discharge specific capacity, excellent cycle stability and good thermal stability. With the popularization of new energy vehicles and energy storage batteries, a large number of lithium-ion battery factories are developing rapidly, and lithium-ion batteries will produce some defective products during the preparation process. Especially before the battery is filled with liquid, some scrapping is caused by processes such as coating, cutting, and pairing. The positive electrode materials of these scrapped pole pieces or winding cores themselves are basically not destroyed and the structure of the positive electrode materials themselves remains stable, and there is a possibility of direct repair, so there is an urgent need to seek a simple and efficient recycling method to deal with the scrapped pole pieces or winding cores. In addition, with the increase in the service life, a large number of retired batteries will be generated. If not handled properly, these retired batteries will not only cause waste of resources, but also pose a potential threat to the environment due to the heavy metals, electrolytes and other components contained in the batteries. Therefore, establishing an effective positive electrode material repair and recycling system has become a technical problem that needs to be solved urgently.

[0090] In the related technologies, pyrometallurgy and hydrometallurgy are generally used in the process of repairing and recycling positive electrode materials, but these methods have many problems. For example, the method lacks a complete set of integrated technical equipment for resource utilization of all components, and it is impossible to take into account both high-value and low-value resources and fully recover high- and low-concentration components. In addition, these methods are in urgent need of short-range and efficient technical processes to achieve cost reduction and efficiency improvement, but the current process is cumbersome, the amount of reagents used is large, the wastewater pressure is high, and the process cost is high. This is the main outstanding problem of the current wet process. At the same time, insufficient optimization of the process is also a problem, resulting in a large amount of by-product solid waste and a lot of waste of resources. For example, the amount of ferrophosphorus is large, the quality is poor, and it is difficult to utilize. The utilization cost of the crystallization by-product solid waste in the lithium extraction process is high, the separation of lithium and sodium is difficult, and the lithium loss is high. These problems not only increase the cost of recovery, but may also cause secondary environmental pollution.

[0091] For the positive electrode sheets that are not injected with liquid, there is currently a process method that uses a high-temperature sintering method under an inert atmosphere. The positive electrode sheets are crushed and then calcined at high temperature to obtain positive electrode materials and aluminum foil, and then positive electrode materials such as lithium iron phosphate are obtained through sorting. However, under this process, high temperature will cause lithium to volatilize in the form of lithium carbonate, and the problem of low recovery rate is difficult to solve. The high-temperature calcination process requires a lot of energy and is costly. In addition, a large amount of Al impurities will be introduced during the separation and crushing after sintering, affecting the electrochemical properties of the positive electrode material. In addition, due to the protection of inactive gas during the sintering process, the carbon components such as SP originally contained in the electrode sheet are relatively high. This part of the components exists in the LFP material. Since the carbon density is low and does not contribute to the discharge capacity, it will lead to a decrease in the battery energy density.

[0092] In this regard, the present application provides a method for repairing and recycling positive electrode materials, which can reduce pollution, energy consumption and cost, and improve the repair and recovery rate of positive electrode materials. Figure 5 The method of repairing and recycling positive electrode materials is introduced.

[0093] In one embodiment, Figure 5 As shown, step S102, obtaining the repaired and recycled positive electrode material, includes the following steps S502 to S506.

[0094] S502: pre-treating the waste materials to obtain positive electrode fragments; the waste materials include positive electrode materials.

[0095] The waste material includes at least one of a lithium-ion battery cell and a positive electrode sheet that are not filled with liquid. Both the lithium-ion battery cell and the positive electrode sheet include positive electrode materials, and the positive electrode materials include positive electrode active substances and positive electrode inactive substances. Exemplarily, the lithium-ion battery cell that is not filled with liquid is split to obtain positive electrode sheets; and the positive electrode sheets are shredded to obtain positive electrode fragments. The size of the positive electrode fragments is smaller than the size of the positive electrode sheets. Exemplarily, the size of the positive electrode fragments can be determined based on the equipment used to shred the positive electrode sheets.

[0096] In applications, discarded battery cells can be disassembled and shredded, and discarded positive electrode sheets can be shredded, which helps to increase the contact area between the positive electrode fragments and the aqueous solution in subsequent steps, thereby increasing the separation rate of the positive electrode active material, and also helps to improve the flow rate and process efficiency.

[0097] S504: placing the positive electrode fragments in an aqueous solution for separation treatment to obtain separated positive electrode materials.

[0098] The aqueous solution refers to a solution that can separate the positive electrode material from the positive electrode current collector and does not react with the positive electrode material. The aqueous solution includes at least one of tap water, deionized water, ethanol, acetone, dimethyl carbonate (DMC), N-methylpyrrolidone (NMP), citric acid and acetic acid. For example, the aqueous solution includes tap water; for another example, the aqueous solution includes deionized water and DMC. This is only an exemplary description, and one or more of them can be selected and mixed according to actual needs without making too many restrictions.

[0099] S506: Dry and crush the separated positive electrode material to obtain repaired and recycled positive electrode material.

[0100] The separated positive electrode material will contain an aqueous solution, and in this regard, a drying device can be used for drying, which is helpful for subsequent processes and improves the recovery rate of the positive electrode material. The drying device can be a blast oven, a vacuum oven, a drying furnace, a double cone dryer or other suitable types, which are not limited here.

[0101] After drying, the dried positive electrode material can be coarsely crushed by coarse crushing equipment to obtain coarsely crushed positive electrode material, and then the coarsely crushed positive electrode material can be finely crushed by fine crushing equipment under an inactive gas atmosphere to obtain repaired and recycled positive electrode material.

[0102] The size of the repaired and recovered positive electrode material meets the requirements for the preparation of positive electrode sheets, and the size of the repaired and recovered positive electrode material is smaller than the size of the coarsely crushed positive electrode material, and the size of the coarsely crushed positive electrode material is smaller than the size of the dried positive electrode material. It should be noted that the size of the repaired and recovered positive electrode material can be determined based on the size requirements of the subsequent preparation of positive electrode sheets and factors such as fine crushing processing equipment, and the size of the coarsely crushed positive electrode material can be determined based on the coarse crushing processing equipment, and is not specifically limited here.

[0103] Among them, the coarse crushing equipment may include at least one of a jaw crusher, a roller mill, a shredder, a pin mill, a ball mill, and a sand mill, or other suitable types, which are not limited here. The size range of the coarsely crushed positive electrode material can be 10μm~200μm, for example, it can be 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm or 200μm, or any other value between 10μm~200μm, which is not limited here.

[0104] The fine crushing equipment may include at least one of a jet mill, a mechanical mill, a pin mill, and a grading mill, or other suitable types, which are not limited here. The size range of the repaired and recycled positive electrode material may be 0.5 μm to 5 μm, for example, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4 μm, 4.5 μm or 5.0 μm, or any other value between 0.5 μm and 5 μm, which are not limited here.

[0105] It can be understood that the size of the repaired and recycled positive electrode material is at the micron level. Therefore, the introduction of inactive gas to protect the positive electrode material during the fine crushing process can avoid oxidation and help improve the repair and recovery effect of the positive electrode material. Exemplarily, the inactive gas includes at least one of nitrogen (N2) and an inert gas, wherein the inert gas includes argon (Ar), helium (He), etc., which are not limited here.

[0106] The above-mentioned lithium iron phosphate material recovery method dries the positive electrode active material to obtain dry active material, coarsely crushes the dry active material to obtain active material particles, and finely crushes the active material particles under an inactive gas atmosphere to obtain lithium iron phosphate particles, wherein the size of the lithium iron phosphate particles is smaller than the size of the active material particles, so that lithium iron phosphate particles that meet the size of electrode preparation can be obtained, and after subsequent classification treatment, the lithium iron phosphate material can be effectively recovered, the process is simple, the energy consumption and pollution are low, and the economy is high.

[0107] The preparation method of the positive electrode material provided in the embodiment of the present application pre-treats the waste material to obtain positive electrode fragments, and places the positive electrode fragments in an aqueous solution to obtain the separated positive electrode material, and then dries and crushes the positive electrode material to obtain the repaired and recovered positive electrode material, thereby realizing the repair and recovery of the positive electrode material in the waste material. The method adopts a direct repair positive electrode material process. Compared with the traditional hydrometallurgical and pyrometallurgical processes, the positive electrode material does not need to react chemically with substances such as acids and alkalis, nor does it need to be sintered at high temperature, that is, it avoids the use of acids and alkalis and high-temperature sintering in the related art, generates less pollution, consumes less energy, and has a lower process cost; and the content of positive electrode current collector components such as aluminum (AL) in the repaired and recovered positive electrode material is low, which can effectively improve the safety of subsequent battery preparation; in addition, the inactive substances in the repaired and recovered positive electrode material in the method can be preserved relatively intact, or maintain good activity, which provides a prerequisite for reducing the amount of inactive substances in the subsequent preparation of new positive electrode materials, so as to achieve the purpose of reducing costs.

[0108] Based on the same inventive concept, the embodiment of the present application further provides a positive electrode material, which is obtained by the above-mentioned preparation method of the positive electrode material. The specific definition of the preparation method of the positive electrode material can be found in the above description, and will not be repeated here.

[0109] Based on the same inventive concept, in some embodiments, Figure 6 As shown, a method for preparing a battery is provided, and the method includes the following steps S602 to S610.

[0110] S602: Obtain a positive electrode material using a positive electrode material preparation method.

[0111] The method for preparing the positive electrode material may be the method for preparing the positive electrode material provided in any of the aforementioned embodiments. The specific contents may be referred to the above description and will not be repeated here.

[0112] S604: Mix the positive electrode material and the solvent to obtain positive electrode slurry.

[0113] The solvent can be understood as a volatile solution that does not chemically react with the positive electrode material. For example, the solvent can be an organic solvent, which can include one or more of N-methylpyrrolidone (NMP), acetone, ether and ethanol, or other suitable solutions, which are not specifically limited here.

[0114] In applications, the newly prepared positive electrode material can be added to an appropriate amount of solvent such as NMP and stirred to initially disperse the solid particles.

[0115] S606: coating the positive electrode slurry on one side of the positive electrode current collector.

[0116] The positive electrode current collector may include aluminum foil or carbon-coated aluminum foil, wherein the carbon-coated aluminum foil includes an aluminum foil and a carbon-coated layer stacked. Taking the positive electrode current collector including aluminum foil as an example, the positive electrode slurry may be evenly coated on the aluminum foil. Figure 7 As shown, taking the positive electrode current collector including carbon-coated aluminum foil as an example, the positive electrode slurry can be evenly coated on the side of the carbon-coated layer away from the aluminum foil.

[0117] The thickness of the carbon coating layer can be any suitable value. For example, the thickness of the carbon coating layer can be less than 1 micron, such as 0.1μm, 0.2μm, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm or other values ​​less than 1μm, which are not limited too much here.

[0118] The functions of the carbon coating layer include: 1. Reducing the interface impedance of the positive electrode current collector, reducing polarization, and improving the cycle life and rate performance; 2. Improving the adhesion between the positive electrode active material and the positive electrode current collector, reducing the amount of binder used, and reducing the production cost; 3. Preventing the positive electrode current collector from being corroded and oxidized, thereby extending the battery life.

[0119] In applications, a suitable positive electrode current collector can be selected according to actual needs, and no limitation is made here.

[0120] The coating thickness of the positive electrode slurry can be any suitable value. For example, the coating thickness range can be less than or equal to 46μm, such as 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 46μm or other values ​​less than or equal to 46μm, which are not limited here.

[0121] S608: Drying the positive electrode current collector coated with the positive electrode slurry to obtain a positive electrode sheet.

[0122] It is understood that the positive electrode slurry contains a solvent, so the positive electrode current collector coated with the positive electrode slurry can be dried to remove the solvent to obtain a positive electrode sheet. In the application, a drying device can be used for drying, wherein the drying device includes but is not limited to a vacuum drying oven, an oven, a microwave dryer or other types of drying equipment, which are not specifically limited here.

[0123] S610: Assemble the positive electrode sheet, the negative electrode sheet, the separator and the electrolyte to obtain a battery.

[0124] Figure 7 A schematic diagram of the structure of a battery is provided. Figure 7As shown, the lithium-ion battery includes a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte (not shown in the figure). The separator is located between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a positive electrode current collector and a positive electrode material. The positive electrode material includes a positive electrode active material and a positive electrode inactive material. The positive electrode active material may include at least one of lithium iron phosphate (LFP), nickel manganese cobalt oxide (NMC), nickel cobalt aluminum oxide (NCA), lithium cobalt oxide (LCO), lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide and other types of materials. The positive electrode inactive material may include a conductive agent and a binder, wherein the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene, sodium carboxymethyl cellulose and other types of materials; the conductive agent may include at least one of conductive carbon black (SP), graphite, carbon nanotubes, graphene, conductive polymers and other types of materials. The positive electrode current collector includes aluminum foil, or the positive electrode current collector includes aluminum foil and a carbon coating layer, and the carbon coating layer is located between the aluminum foil and the positive electrode material. The negative electrode sheet includes a negative electrode active material and a negative electrode current collector. The negative electrode current collector layer may include copper foil or other suitable materials, and the negative electrode current collector may include graphite or other suitable materials. The electrolyte may be an electrolyte containing a lithium salt.

[0125] The preparation method of the battery provided in the embodiment of the present application adopts the preparation method of the positive electrode material to obtain the positive electrode material, mix the positive electrode material and the solvent to obtain the positive electrode slurry, apply the positive electrode slurry on one side of the positive electrode collector, dry the positive electrode collector coated with the positive electrode slurry to obtain the positive electrode sheet, and assemble the positive electrode sheet, the negative electrode sheet, the separator and the electrolyte to obtain the battery. In this way, the battery can be prepared using the newly prepared positive electrode material, realizing the reuse of the positive electrode material, effectively reducing the battery preparation cost, and in the preparation process of the positive electrode material, the proportion of positive electrode inactive substances is reduced, and the proportion of positive electrode active substances is increased, which can improve battery performance such as battery capacity; in addition, in the preparation process of the positive electrode material, a direct repair method is adopted to obtain the repaired and recovered positive electrode material, realizing the repair and recovery of the positive electrode material, reducing pollution, energy consumption and cost, improving the environmental protection of battery preparation, and further reducing the battery preparation cost.

[0126] In one embodiment, Figure 8 As shown, a method for preparing a battery is provided, and the method includes the following steps S802 to S824.

[0127] S802: disassembling the waste lithium iron phosphate coil core that has not been injected with liquid to obtain positive electrode sheets, and / or shredding the discarded positive electrode sheets to obtain positive electrode fragments.

[0128] The positive electrode fragments at least include positive electrode materials, and the positive electrode materials at least include LFP, PVDF and SP.

[0129] S804: Soaking the positive electrode fragments in an aqueous solution and obtaining the separated positive electrode material.

[0130] The solution components of the aqueous solution include a mixture of one or more liquids such as tap water, deionized water, ethanol, acetone, DMC, NMP, citric acid, acetic acid, etc.

[0131] S806: Place the positive electrode material into a drying device for high-temperature drying.

[0132] The drying equipment may be a blast oven, a vacuum oven, a drying furnace or a double cone dryer.

[0133] S808: The dried positive electrode material is put into a coarse crushing device for coarse crushing to obtain a coarsely crushed positive electrode material.

[0134] The coarse crushing equipment may be a jaw crusher, a roller mill, a shredder, a pin mill, a ball mill or a sand mill. The size of the positive electrode material after coarse crushing may range from 10 μm to 200 μm.

[0135] S810: Under an inactive gas atmosphere, the coarsely crushed positive electrode material is put into a fine crushing device for fine crushing to obtain a repaired and recycled positive electrode material.

[0136] The inactive gas may be nitrogen or argon. The fine crushing equipment may be a jet mill, a mechanical mill, a pin mill or a grading mill. The size range of the repaired and recycled positive electrode material may be 0.5 μm to 5 μm.

[0137] S812: Obtain the battery type of the battery to be prepared, and obtain the general ingredient ratio of the positive electrode material according to the battery type.

[0138] The battery types include button cells, soft pack cells, square shell cells, cylindrical cells, and other shapes or types of lithium-ion batteries. Among them, the general ratio of LFP:PVDF:SP in button cells is 90:5:5, and the general ratio of LFP:PVDF:SP in non-button cells is 96.5:2:1.5.

[0139] S814: Determine a reduction range of the proportion of PVDF according to the general proportion value of PVDF in the general proportion, and determine a reduction range of the proportion of SP according to the general proportion value of SP in the general proportion.

[0140] In the application, the preset lower limit values ​​of the proportion reduction of PVDF and SP are obtained, where the preset lower limit values ​​of the proportion reduction of PVDF and SP are both 0.01%. Then, the range between the lower limit value of the proportion reduction and the general proportion value is determined as the proportion reduction range; in button batteries, the proportion reduction range of PVDF is 0.01%~5%, and the proportion reduction range of SP is 0.01%~5%; in non-button batteries, the proportion reduction range of PVDF is 0.01%~2%, and the proportion reduction range of SP is 0.01%~1.5%.

[0141] S816: Determine the proportion ranges of PVDF and SP respectively according to the general proportion value and the proportion reduction range.

[0142] In button cells, the proportion of PVDF ranges from 0 to 4.99%, and the proportion of SP decreases to 0 to 4.99%; in non-button cells, the proportion of PVDF decreases to 0 to 1.99%, and the proportion of SP decreases to 0 to 1.49%.

[0143] S818: preparing target inactive substances for the repaired and recovered positive electrode materials according to the proportion range to obtain newly prepared positive electrode materials.

[0144] For button cells, PVDF and SP are formulated for the repaired and recycled positive electrode materials according to the proportion of PVDF in the range of 0-4.99% and the proportion of SP in the range of 0-4.99%. For non-button cells, PVDF and SP are formulated for the repaired and recycled positive electrode materials according to the proportion of PVDF in the range of 0-1.99% and the proportion of SP in the range of 0-1.49%. Figures 9 to 11 The scanning electron microscope schematic diagrams of the repaired and recycled positive electrode materials at different sizes are provided respectively. As shown in Table 1, different ingredient ratios of the positive electrode materials of button cells are provided.

[0145] Table 1

[0146]

[0147] S820: Add the newly prepared positive electrode material into an appropriate amount of organic solvent and stir to obtain a positive electrode slurry.

[0148] The organic solvent may be N-methylpyrrolidone (NMP).

[0149] S822: The positive electrode slurry is evenly coated on the aluminum foil current collector, and dried in a vacuum drying oven to remove the organic solvent to obtain a positive electrode sheet.

[0150] S824: Assemble the positive electrode sheet, the negative electrode sheet, the separator and the electrolyte into a lithium-ion battery.

[0151] The preparation method of the above-mentioned battery adopts a method of directly repairing the positive electrode material, avoiding the use of acid and alkali and high-temperature sintering in related methods, resulting in less pollution, lower energy consumption, and lower process cost; and, the Al content in the repaired and recovered positive electrode material in this method is low, which can effectively improve the safety of battery preparation; in addition, the PVDF and SP components in the repaired and recovered positive electrode material in this method are relatively well preserved, providing a prerequisite for reducing the corresponding components in subsequent battery preparation to reduce the battery manufacturing cost; in addition, compared with the conventional battery manufacturing formula, that is, the general ingredient ratio, the battery preparation method provided in the embodiment of the present application can effectively reduce the proportion of PVDF and SP, two types of auxiliary materials that do not contribute to the battery capacity, thereby increasing the proportion of LFP main materials in the formula, thereby improving the discharge capacity and other performance of the battery.

[0152] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0153] Based on the same inventive concept, the present application also provides a battery, which is obtained by the above-mentioned method for preparing the battery. The specific definition of the method for preparing the battery can be found in the above description, and will not be repeated here.

[0154] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0155] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for preparing a positive electrode material, characterized in that: The method comprises: Obtaining the general proportion of positive electrode materials in the battery to be prepared, and obtaining the positive electrode materials for repair and recycling; Determining a proportion range of the target inactive substance in the positive electrode material according to the general proportion; an upper limit value of the proportion range is less than a general proportion value of the target inactive substance in the general proportion; The target inactive substance is formulated into the repaired and recovered positive electrode material according to the proportion range to obtain a newly prepared positive electrode material.

2. The method according to claim 1, characterized in that The determining the proportion range of the target inactive substance in the positive electrode material according to the general proportion includes: Determining a reduction range of the proportion of the target inactive substance according to the general proportion value of the target inactive substance in the general ingredient ratio; The proportion range of the target inactive substance is determined according to the general proportion value and the proportion reduction range.

3. The method according to claim 2, characterized in that The step of determining the reduction range of the proportion of the target inactive substance according to the general proportion value of the target inactive substance in the general ingredient ratio includes: Obtaining a preset lower limit value of the proportion reduction of the target inactive substance; The range between the lower limit value of the proportion reduction and the general proportion value is determined as the proportion reduction range.

4. The method according to claim 2, characterized in that: The determining the proportion range of the target inactive substance according to the general proportion value and the proportion reduction range includes: Determine the difference between the general proportion value and the lower limit value of the proportion reduction range as the upper limit value of the proportion range; The difference between the general proportion value and the upper limit value of the proportion reduction range is determined as the lower limit value of the proportion range.

5. The method according to any one of claims 1 to 4, characterized in that: The target inactive substance includes at least one of a conductive agent and a binder, wherein the maximum value of the conductive agent's proportion range is less than the general proportion value of the conductive agent in the general ingredient ratio, and the maximum value of the binder's proportion range is less than the general proportion value of the binder in the general ingredient ratio.

6. The method according to any one of claims 1 to 4, characterized in that: The method of obtaining the general proportion of the positive electrode material in the battery to be prepared comprises: Obtaining the battery type of the battery to be prepared; The general proportion of the positive electrode material is obtained according to the battery type.

7. The method according to any one of claims 1 to 4, characterized in that: The method of obtaining the repaired and recycled positive electrode material comprises: Pre-treating waste materials to obtain positive electrode fragments; the waste materials include positive electrode materials; placing the positive electrode fragments in an aqueous solution to obtain separated positive electrode materials; The separated positive electrode material is dried and crushed to obtain the repaired and recovered positive electrode material.

8. A positive electrode material, characterized in that The cathode material is obtained by the method for preparing the cathode material according to any one of claims 1 to 7.

9. A method for preparing a battery, characterized in that: The method comprises: Obtaining a positive electrode material by using the method for preparing a positive electrode material according to any one of claims 1 to 7; Mixing the positive electrode material and a solvent to obtain a positive electrode slurry; Applying the positive electrode slurry on one side of the positive electrode current collector; Drying the positive electrode current collector coated with the positive electrode slurry to obtain a positive electrode sheet; The positive electrode sheet, the negative electrode sheet, the separator and the electrolyte are assembled to obtain a battery.

10. A battery, characterized in that: The battery is obtained by the preparation method of the battery as claimed in claim 9.

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