Method for separating positive electrode material and current collector in waste lithium battery

Abstract

The invention provides a method for separating a positive electrode material and a current collector in a waste lithium battery, and the method comprises the following steps: carrying out electric pulse heating treatment on a positive plate and an alkaline substance to obtain the positive electrode material and the current collector; wherein the alkaline substance comprises one or more of oxides, hydroxides, carbonates or peroxides of potassium, calcium, sodium, magnesium and aluminum. Therefore, the positive electrode material can be rapidly and nondestructively stripped from the current collector aluminum foil by adopting the electric pulse heating technology, and meanwhile, the alkaline substance is adopted as an auxiliary medium in the electric pulse heating process, so that the separation efficiency of the positive electrode material and the current collector can be improved, and fluorine-containing components in the positive electrode plate can be effectively captured; the deep defluorination of the waste lithium battery positive electrode material is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery recycling, and in particular to a method for separating positive electrode materials and current collectors in waste lithium batteries, and regenerating positive electrode materials and batteries. Background Art

[0002] In recent years, the lithium-ion battery industry has developed rapidly. Due to its advantages such as high energy density, long cycle life and no memory, lithium-ion batteries are widely used in 3C electronic products, power vehicles and chemical energy storage fields, and are a research hotspot in the current new energy field. With the rapid growth of lithium-ion battery applications and demand, a large number of scrapped batteries will be generated. It is estimated that by 2030, more than 1,100 tons of retired lithium-ion batteries will be generated. Environmental problems and resource recycling and reuse issues will also follow.

[0003] The recycling technology route for waste lithium-ion batteries is generally: discharge treatment - disassembly treatment - separation of active substances on aluminum foil - dissolution treatment - resynthesis of new materials. Among them, the separation of active substances on aluminum foil is one of the key links to achieve efficient recycling of lithium-ion batteries. Due to the low adhesion between graphite particles in the negative electrode and copper foil, the graphite in waste lithium-ion batteries can be easily recycled through mechanical treatment. In contrast, the more valuable positive electrode material and aluminum foil are tightly connected by polyvinylidene fluoride (PVDF), which is difficult to separate and recycle by traditional methods.

[0004] Therefore, there is an urgent need to develop a separation method with low energy consumption, high efficiency and effective control of fluorine pollution, so as to achieve lossless stripping of various types of waste lithium-ion battery positive electrode materials. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art to a certain extent. To this end, the present invention provides a method for separating positive electrode materials and current collectors in waste lithium batteries by using electric heating technology. The method uses alkaline substances as auxiliary media and performs heat treatment in an instantaneous high temperature environment to separate the positive electrode sheets of waste lithium ion batteries to obtain positive electrode materials and current collector aluminum foil, while capturing organic fluorine components in the positive electrode materials of waste lithium batteries.

[0006] Therefore, in the first aspect of the present invention, the present invention proposes a method for separating positive electrode materials and current collectors in waste lithium batteries. According to an embodiment of the present invention, the method comprises: subjecting a positive electrode sheet and an alkaline substance to electric pulse heating treatment to obtain the positive electrode material and the current collector; wherein the alkaline substance comprises one or more of oxides, hydroxides, carbonates or peroxides of potassium, calcium, sodium, magnesium and aluminum.

[0007] During the experiment, the inventor unexpectedly discovered that the electric pulse heating technology can be used to quickly and non-destructively peel the positive electrode material from the current collector aluminum foil. At the same time, the use of alkaline substances as auxiliary media in the electric pulse heating process can not only improve the separation efficiency of the positive electrode material and the current collector, but also effectively capture the fluorine-containing components in the positive electrode sheet, and achieve deep defluorination of the positive electrode material of the waste lithium battery. Among them, the introduction of alkaline substances effectively buffers the heat conductivity of the positive electrode sheet, prevents the high-temperature phase change of the low-melting point aluminum foil, and inhibits the aluminum thermal reduction reaction of the aluminum element and the positive electrode material; in addition, the heat insulation effect of the alkaline substance helps to protect the crystal structure and chemical composition of the positive electrode material, reduce heat loss, and enable the separated positive electrode material to be directly used for repair and regeneration or the extraction of valuable metals; in addition, the addition of alkaline substances increases the contact rate between the alkaline group donor and polyvinylidene fluoride, thereby promoting the thermal defluorination reaction and effectively controlling fluorine pollution.

[0008] According to an embodiment of the present invention, the method may further include at least one of the following additional technical features:

[0009] According to an embodiment of the present invention, the alkaline substance covers at least a portion of the surface of both sides of the positive electrode sheet.

[0010] According to an embodiment of the present invention, the alkaline substance includes one or more of calcium carbonate, calcium hydroxide, magnesium carbonate, sodium hydroxide, magnesium hydroxide, calcium oxide, sodium oxide, and magnesium oxide.

[0011] According to an embodiment of the present invention, the alkaline substances covered on both sides of the positive electrode sheet may be the same or different.

[0012] According to an embodiment of the present invention, the positive electrode sheet with both sides covered with the alkaline substance is placed between graphite carriers and then subjected to the electric pulse heating treatment.

[0013] According to an embodiment of the present invention, the mass ratio of the alkaline substance to the positive electrode sheet is (1-10):1.

[0014] According to an embodiment of the present invention, the current of the electric pulse heating treatment is 50A-200A.

[0015] According to an embodiment of the present invention, the time of the electric pulse heating treatment is 1s-10s.

[0016] According to an embodiment of the present invention, after the electric pulse heating treatment, the method further comprises: subjecting the product of the electric pulse heating treatment to ultrasonic cavitation treatment to obtain the positive electrode material and the current collector.

[0017] According to an embodiment of the present invention, the power of the ultrasonic cavitation treatment is 20w-100w.

[0018] According to an embodiment of the present invention, the ultrasonic cavitation treatment time is 5s-60s.

[0019] According to an embodiment of the present invention, the waste lithium battery includes one or more of a lithium cobalt oxide battery, a ternary lithium battery, a lithium iron phosphate battery or a lithium manganese oxide battery.

[0020] In the second aspect of the present invention, the present invention provides a regenerated positive electrode material. According to an embodiment of the present invention, the regenerated positive electrode material is obtained by separating from a waste lithium battery using the method described in the first aspect. As shown above, the method of the present invention can efficiently and non-destructively peel the positive electrode material in the waste lithium battery from the current collector aluminum foil, ensuring that the positive electrode material after peeling maintains its original performance and structure, so that it can be directly used for recycling or recycled after simple repair.

[0021] In the third aspect of the present invention, the present invention proposes a battery. According to an embodiment of the present invention, the battery includes the regenerated positive electrode material described in the second aspect. As shown above, the method of the present invention can efficiently and non-destructively peel the positive electrode material in the waste lithium battery from the current collector aluminum foil, ensuring that the positive electrode material after peeling maintains the original performance and structure, so that its key performance indicators such as charge and discharge capacity and voltage platform are similar to those of the original material, thereby ensuring that the battery prepared therefrom has good energy storage and release capabilities, can meet the basic requirements of battery performance for different application scenarios, and can improve the utilization efficiency of resources, reduce the over-exploitation of natural resources, and reduce costs.

[0022] Beneficial effects:

[0023] 1. The present invention adopts a method combining electric pulse heating and ultrasonic cavitation technology to achieve rapid and non-destructive stripping of positive electrode materials from highly reactive current collectors (aluminum foil). The electric pulse heating device in the present invention can quickly heat the raw materials from room temperature to a high temperature of 1000 to 3000°C within a few seconds. This transient high-temperature treatment can completely destroy the chemical structure of polyvinylidene fluoride without affecting the crystal structure of the positive electrode material, and minimizes the thermal volatilization loss of lithium elements in the positive electrode material. In addition, the product after thermal shock can be treated with low-power ultrasonic cavitation to efficiently separate the positive electrode material from the aluminum foil, and the positive electrode material maintains good performance and structural integrity, and can be directly used in the repair and regeneration or extraction of valuable metals.

[0024] 2. The process energy consumption of the present invention is only one thousandth of that of the traditional low-temperature pyrolysis process, and no external acid or alkali reagents are required in the entire process.

[0025] 3. The present invention uses solid alkaline medium as an auxiliary medium in the electric pulse heating process, which effectively buffers the heat conductivity of the positive electrode sheet, prevents the high-temperature phase change of the low-melting point aluminum foil, and inhibits the aluminothermic reduction reaction between the aluminum element and the positive electrode material. At the same time, the alkaline group of the solid alkaline medium promotes the thermal decomposition behavior of polyvinylidene fluoride. Most importantly, the solid alkaline medium can completely capture the fluorine-containing components in the positive electrode sheet, thereby achieving deep defluorination of the waste lithium battery positive electrode material.

[0026] 4. The positive electrode material separated by the method of the present invention has extremely low organic and inorganic fluorine content, which can effectively avoid strong acid etching caused by HF release during the subsequent roasting and regeneration process. Even if a simple fire roasting and regeneration process is used, a regenerated positive electrode material with good electrochemical properties can be obtained.

[0027] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0029] Figure 1 is a schematic diagram of the distribution and position relationship of alkaline substances on the positive electrode sheet according to an embodiment of the present invention;

[0030] Description of the drawings: 100: alkaline substance; 200: positive electrode sheet; 300: alkaline substance. DETAILED DESCRIPTION

[0031] The embodiments of the present invention are described in detail below, which are intended to explain the present invention but should not be construed as limiting the present invention.

[0032] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0033] For simplicity, only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and any upper limit can be combined with any other upper limit to form an unspecified range. In addition, each separately disclosed point or single value can itself be combined as a lower limit or upper limit with any other point or single value or with other lower limits or upper limits to form an unspecified range.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the terms "including" and "having" in the specification and claims of the present invention and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0035] In this document, the terms “include” or “comprising” are open expressions, that is, including the contents specified in the present invention but not excluding other contents.

[0036] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Further, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0037] my country has seen an industry contradiction between insufficient supply of new lithium battery raw materials and explosive growth of waste lithium batteries. Repairing and regenerating waste lithium batteries or extracting valuable metals is the key to ensuring the sustainable development of the new energy vehicle industry. Stripping the positive electrode material of the positive electrode sheet of waste lithium batteries is a necessary pretreatment process for subsequent resource recycling. However, the positive electrode material is firmly fixed on the aluminum foil carrier with high chemical activity by an organic binder (such as polyvinylidene fluoride), and green and efficient stripping of the positive electrode material is a difficulty in the pretreatment process. Many scholars in my country have begun to study the use of low-temperature pyrolysis, reagent dissolution, mechanochemistry and other methods to separate the positive electrode material from the current collector aluminum foil. Although these methods can destroy the bonding force of the organic binder and achieve the separation of the positive electrode material and the current collector in the waste lithium battery, the above methods have problems such as long processing time, complex process flow, and inability to completely decompose the organic binder. In addition, polyvinylidene fluoride still remains between the particles of the obtained positive electrode material, which will cause the particles to agglomerate and may produce fluorine-containing pollutants in the subsequent repair and regeneration or metal extraction process.

[0038] In view of this, the inventor has developed a separation method with low energy consumption, high efficiency and effective control of fluorine pollution after a large number of experiments. This method uses alkaline substances as auxiliary media and adopts electric pulse heating technology to separate the positive electrode material and the current collector in the waste lithium battery. This method can not only achieve non-destructive stripping of the positive electrode material in the waste lithium battery, so that the separation efficiency of the positive electrode material and the current collector aluminum foil reaches more than 90%, but also will not change the crystal structure of the positive electrode material, and minimize the thermal volatilization loss of lithium elements in the positive electrode material. In addition, this method can also effectively capture the fluorine-containing components in the positive electrode sheet, realize the deep defluorination of the positive electrode material of the waste lithium battery, and thus effectively control the fluorine pollution. The following will introduce in detail the method of separating the positive electrode material and aluminum foil in the waste lithium battery, the regenerated positive electrode material and the battery.

[0039] Method for separating positive electrode material and aluminum foil from waste lithium batteries

[0040] In a first aspect of the present invention, the present invention provides a method for separating positive electrode materials and current collectors in waste lithium batteries. According to an embodiment of the present invention, the method comprises: subjecting a positive electrode sheet and an alkaline substance to electric pulse heating treatment to obtain the positive electrode material and the current collector; wherein the alkaline substance comprises one or more of oxides, hydroxides, carbonates or peroxides of potassium, calcium, sodium, magnesium and aluminum.

[0041] During the experiment, the inventor unexpectedly found that the electric pulse heating technology can be used to quickly and non-destructively peel the positive electrode material from the current collector. At the same time, the use of alkaline substances as auxiliary media in the electric pulse heating process can not only improve the separation efficiency of the positive electrode material and the current collector, but also effectively capture the fluorine-containing components in the positive electrode sheet, and achieve deep defluorination of the positive electrode material of the waste lithium battery. Among them, the introduction of alkaline substances effectively buffers the heat conductivity of the positive electrode sheet, prevents the high-temperature phase change of the low-melting point current collector aluminum foil, and inhibits the aluminum thermal reduction reaction of the aluminum element and the positive electrode material; in addition, the heat insulation effect of the alkaline substance helps to protect the crystal structure and chemical composition of the positive electrode material, reduce heat loss, and enable the separated positive electrode material to be directly used for repair and regeneration or the extraction of valuable metals; in addition, the addition of alkaline substances increases the contact rate between the alkaline group donor and the organic binder (such as polyvinylidene fluoride), thereby promoting the thermal defluorination reaction and effectively controlling fluorine pollution.

[0042] In some embodiments of the present invention, reference Figure 1, the alkaline substance is covered on at least part of the surface of both sides of the positive electrode sheet. 100 and 300 represent alkaline substances, and 200 represents a positive electrode sheet. As a result, the alkaline substance not only improves the separation efficiency of the positive electrode material and the current collector in the waste lithium battery, but also plays a good heat insulation role, effectively buffers the heat conductivity of the positive electrode sheet, prevents the high-temperature phase change of the low-melting point aluminum foil, and inhibits the aluminum thermal reduction reaction of the aluminum element and the positive electrode material; in addition, the alkaline group of the solid alkaline medium promotes the thermal decomposition behavior of the organic binder polyvinylidene fluoride, thereby capturing the fluorine-containing components in the positive electrode sheet, and realizing the deep defluorination of the positive electrode material of the waste lithium battery.

[0043] In some embodiments of the present invention, the alkaline substance includes one or more of calcium carbonate, calcium hydroxide, magnesium carbonate, sodium hydroxide, magnesium hydroxide, calcium oxide, sodium oxide, and magnesium oxide. Thus, the above-mentioned alkaline substances can increase the contact rate between the alkaline group donor and the organic binder polyvinylidene fluoride, and promote the thermal defluorination reaction. At the same time, the heat loss of the crystal structure and chemical composition of the positive electrode material is avoided.

[0044] In some embodiments of the present invention, the alkaline substances covered on both sides of the positive electrode sheet may be the same or different. According to an embodiment of the present invention, the alkaline substance 100 may be sodium oxide, and the alkaline substance 200 may be magnesium oxide. According to an embodiment of the present invention, the alkaline substance 200 may be sodium oxide, and the alkaline substance 100 may be magnesium oxide.

[0045] In some embodiments of the present invention, the positive electrode sheet covered with alkaline substances on both sides is placed between graphite carriers, and then the electric pulse heating treatment is performed. Therefore, the graphite carrier can, on the one hand, evenly transfer the electric pulse current to various parts of the positive electrode sheet, so that a uniform electric field is formed on the positive electrode sheet, ensuring uniform heat generation during the electric pulse heating process, avoiding local overheating or insufficient heating, thereby improving the uniformity and consistency of the separation effect; on the other hand, it plays a buffering role, protecting the positive electrode sheet from direct damage at high temperature, reducing the material structure damage caused by thermal stress concentration, and ensuring the integrity and performance of the positive electrode material.

[0046] In some embodiments of the present invention, the graphite carrier is selected from carbon paper. According to an embodiment of the present invention, the positive electrode sheet covered with alkaline substances on both sides is placed between two sheets of carbon paper before the electric pulse heating treatment is performed.

[0047] In some embodiments of the present invention, the mass ratio of the alkaline substance to the positive electrode sheet is (1-10): 1. For example, it can be 1: 1, 2: 1, 3: 1, 4: 1, 5: 1, 6: 1, 7: 1, 8: 1, 9: 1, 10: 1, etc., or it can be a range composed of any of the above values. Thus, by making the mass of the alkaline substance and the positive electrode sheet within the above range, the separation rate of the positive electrode material and the current collector can be improved, and the contact rate between the alkaline group donor and the organic binder polyvinylidene fluoride can be increased, thereby promoting the thermal defluorination reaction.

[0048] In some embodiments of the present invention, the alkaline substance is selected from calcium carbonate and magnesium carbonate, and the mass ratio of the calcium carbonate and magnesium carbonate to the positive electrode sheet is (2-7): 1. For example, it can be 2: 1, 3: 1, 4: 1, 5: 1, 6: 1, 7: 1, etc., or can be a range composed of any of the above values.

[0049] In the present invention, calcium carbonate and magnesium carbonate are decomposed into calcium oxide or magnesium oxide and carbon dioxide respectively under the action of high temperature and electric pulse. This process not only promotes the degradation of organic binder PVDF, but also effectively controls fluoride pollution. Calcium carbonate or magnesium carbonate is decomposed into calcium oxide (CaO) or magnesium oxide (MgO) and carbon dioxide (CO 2 ), the calcium ions (Ca 2+ ) or magnesium ions in magnesium oxide (Mg 2+ ) will adsorb fluorine atoms (F) in PVDF to form coordination bonds, causing the electrons of fluorine atoms to migrate to calcium ions or magnesium ions, thereby inducing PVDF decoupling, forming Ca-F or Mg-F ion bonds, and destroying the chemical structure of PVDF. At the same time, high-temperature carbon dioxide will undergo oxidative dehydrogenation reactions with the CH bonds in the PVDF monomer to form carbon-carbon double bonds, significantly reducing its mechanical properties and heat resistance. The newly formed calcium oxide or magnesium oxide will also adsorb hydrogen fluoride (HF) formed by further degradation of low-polymerization PVDF, achieving deep defluorination of waste lithium battery positive electrode materials and effectively controlling fluoride pollution.

[0050] In some embodiments of the present invention, the alkaline substance is selected from calcium hydroxide, and the mass ratio of the calcium hydroxide to the positive electrode sheet is (1-5): 1. For example, it can be 1: 1, 2: 1, 3: 1, 4: 1, 5: 1, etc., or can be a range composed of any of the above values.

[0051] In some embodiments of the present invention, the alkaline substance is selected from sodium hydroxide, and the mass ratio of the sodium hydroxide to the positive electrode sheet is (6-10): 1. For example, it can be 6: 1, 7: 1, 8: 1, 9: 1, 10: 1, etc., or can be a range composed of any of the above values.

[0052] In some embodiments of the present invention, the alkaline substance is selected from magnesium hydroxide, and the mass ratio of the magnesium hydroxide to the positive electrode sheet is (4-8): 1. For example, it can be 4: 1, 5: 1, 6: 1, 7: 1, 8: 1, etc., or can be a range composed of any of the above values.

[0053] In the present invention, calcium hydroxide, sodium hydroxide or magnesium hydroxide is decomposed into calcium oxide, sodium oxide or magnesium oxide, and water under the action of high temperature and electric pulse. This process not only promotes the degradation of the organic binder PVDF, but also effectively inhibits the aluminothermic reduction reaction between the positive electrode material and the aluminum foil. Calcium hydroxide, sodium hydroxide or magnesium hydroxide is decomposed into calcium oxide (CaO), sodium oxide (Na 2 O) or magnesium oxide (MgO), and water (H 2 O), the calcium ions (Ca 2+ ), sodium ions in sodium oxide (Na + ) or magnesium ions in magnesium oxide (Mg 2+ ) will adsorb fluorine atoms (F) in PVDF to form coordination bonds, causing the electrons of fluorine atoms to migrate to calcium ions, sodium ions or magnesium ions, thereby inducing PVDF decoupling and forming Ca-F, Na-F or Mg-F ion bonds, destroying the chemical structure of PVDF. At the same time, the enthalpy change of the thermal decomposition process of hydroxide is greater than zero, and its thermal decomposition process will absorb additional heat, avoiding thermal degradation of the positive electrode material caused by the aluminum thermal reduction reaction.

[0054] In some embodiments of the present invention, the alkaline substance is selected from calcium oxide, and the mass ratio of the calcium oxide to the positive electrode sheet is (2-6): 1. For example, it can be 2: 1, 3: 1, 4: 1, 5: 1, 6: 1, etc., or can be a range composed of any of the above values.

[0055] In some embodiments of the present invention, the alkaline substance is selected from sodium oxide and magnesium oxide, and the mass ratio of the sodium oxide to the positive electrode sheet is (1-2): 1, and the mass ratio of the magnesium oxide to the positive electrode sheet is (1-2): 1. For example, it can be 1: 1, 2: 1, etc., or it can be a range composed of any of the above values.

[0056] In the present invention, calcium oxide, sodium oxide or magnesium oxide will adsorb fluorine atoms (F) in PVDF under high temperature and electric pulses to form coordination bonds, prompting the electrons of fluorine atoms to migrate to calcium ions, sodium ions or magnesium ions, thereby inducing PVDF decoupling to form Ca-F, Na-F or Mg-F ion bonds, and destroying the chemical structure of PVDF.

[0057] It should be noted that in the present invention, the electric pulse heating technology uses electric pulses to quickly and selectively heat the low-resistance carbonaceous substrate, completing ultra-high temperature oscillation within a few seconds, thereby achieving transient thermal shock of the raw materials. In some embodiments of the present invention, the positive electrode sheet of the waste lithium battery and the carbon paper layer of the alkaline substance are connected to the positive and negative electrodes of the power supply, and a pulse current is applied to the carbon paper layer, and then according to Joule's law (Q = I 2 Rt) converts electrical energy into thermal energy, and controls the thermal shock temperature of the positive electrode of the waste lithium battery by adjusting the current size and the duration of the electric pulse.

[0058] In some embodiments of the present invention, the current of the electric pulse heating treatment is 50A-200A. For example, it can be 50A, 70A, 100A, 120A, 150A, 170A, 200A, etc., or it can be a range composed of any of the above numerical values. In some embodiments of the present invention, the time of the electric pulse heating treatment is 1s-10s. For example, it can be 1s, 2s, 3s, 4s, 5s, 6s, 7s, 8s, 9s, 10s, etc., or it can be a range composed of any of the above numerical values. Therefore, by making the conditions of the electric pulse heating treatment within the above range, the chemical structure of the organic binder can be completely destroyed, and the crystal structure of the positive electrode material will not be changed, and the heat loss volatilization of the lithium element in the positive electrode material is reduced, so as to achieve efficient separation of the positive electrode material and the current collector.

[0059] In some embodiments of the present invention, after the electric pulse heating treatment, it further includes: subjecting the product of the electric pulse heating treatment to ultrasonic cavitation treatment to obtain the positive electrode material and the current collector. According to an embodiment of the present invention, the power of the ultrasonic cavitation treatment is 20w-100w, for example, it can be 20w, 40w, 60w, 80w, 100w, etc., or it can be a range composed of any of the above numerical values. According to an embodiment of the present invention, the time of the ultrasonic cavitation treatment is 5s-60s. For example, it can be 5s, 10s, 20s, 30s, 40s, 50s, 60s, etc., or it can be a range composed of any of the above numerical values. Thus, efficient separation of the positive electrode material and the current collector can be achieved.

[0060] In some embodiments of the present invention, the positive electrode sheet is obtained by the following method: soaking the waste lithium battery in a sodium chloride solution; drying the soaked waste lithium battery; and manually disassembling the dried waste lithium battery to obtain the positive electrode sheet. Thus, a safe positive electrode sheet without hidden dangers can be obtained.

[0061] It should be noted that the present invention does not specifically limit the specific type of waste lithium batteries, as long as the waste lithium batteries have positive electrode materials, current collectors and organic binders. In some embodiments of the present invention, the waste lithium batteries may be, but are not limited to, one or more of lithium cobalt oxide batteries, ternary lithium batteries, lithium iron phosphate batteries or lithium manganese oxide batteries. In some embodiments of the present invention, the current collector may be aluminum foil, and the organic binder may be polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), polyvinyl alcohol (PVA), sodium alginate (Alg), β-cyclodextrin polymer (β-CDp), polypropylene emulsion (LA132) and polytetrafluoroethylene (PTFE), etc.

[0062] Recycled cathode materials and batteries

[0063] In the second aspect of the present invention, the present invention provides a regenerated positive electrode material. According to an embodiment of the present invention, the regenerated positive electrode material is obtained by separating from a waste lithium battery using the method described in the first aspect. As shown above, the method of the present invention can efficiently and non-destructively peel the positive electrode material in the waste lithium battery from the current collector aluminum foil, ensuring that the positive electrode material after peeling maintains its original performance and structure, so that it can be directly used for recycling or recycled after simple repair.

[0064] In the third aspect of the present invention, the present invention proposes a battery. According to an embodiment of the present invention, the battery includes the regenerated positive electrode material described in the second aspect. As shown above, the method of the present invention can efficiently and non-destructively peel the positive electrode material in the waste lithium battery from the current collector aluminum foil, ensuring that the positive electrode material after peeling maintains the original performance and structure, so that its key performance indicators such as charge and discharge capacity and voltage platform are similar to those of the original material, thereby ensuring that the battery prepared therefrom has good energy storage and release capabilities, can meet the basic requirements of battery performance for different application scenarios, and can improve the utilization efficiency of resources, reduce the over-exploitation of natural resources, and reduce costs.

[0065] Generally, a battery cell includes a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte. During the battery charging and discharging process, active metal ions are embedded and removed back and forth between the positive electrode sheet and the negative electrode sheet. The separator is set between the positive electrode sheet and the negative electrode sheet to play a role of isolation. The electrolyte plays a role of conducting active metal ions between the positive electrode sheet and the negative electrode sheet.

[0066] In some embodiments of the present invention, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one side surface of the positive electrode current collector, and the positive electrode active material layer includes the regenerated positive electrode material.

[0067] In some embodiments of the present invention, the positive electrode current collector may include a metal foil or a composite positive electrode current collector. For example, the metal foil may be aluminum foil. The composite positive electrode current collector may include a polymer material base and a metal layer formed on at least one side of the polymer material base. For example, the composite positive electrode current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT) and other substrates).

[0068] In some embodiments of the present invention, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one side surface of the negative electrode current collector, and the negative electrode active material layer includes a negative electrode material.

[0069] In some embodiments of the present invention, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, a copper foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc.).

[0070] In some embodiments of the present invention, the negative electrode active material may be a negative electrode active material for a battery known in the art. As an example, the negative electrode active material may include at least one of the following materials: natural graphite, artificial graphite, soft carbon, hard carbon, mesophase carbon microspheres, nanocarbon, elemental silicon, silicon oxide, silicon carbon composite, silicon alloy, elemental tin, tin oxide, tin carbon composite, tin alloy, lithium titanate.

[0071] In some embodiments of the present invention, the electrolyte includes a lithium salt and a solvent.

[0072] Exemplarily, the lithium salt includes lithium hexafluorophosphate (LiPF 6 ), at least one of lithium tetrafluoroborate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium trifluoromethanesulfonate, bis(trifluoromethylsulfonyl)methyllithium, and tris(trifluoromethylsulfonyl)methyllithium.

[0073] Exemplarily, the solvent includes at least one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propyl carbonate, ethyl propyl carbonate, ethylene carbonate, vinylene carbonate (VC), methyl vinylene carbonate, 1,2-dimethyl vinylene carbonate, ethyl vinylene carbonate, 1,2-diethyl vinylene carbonate, propyl vinylene carbonate, 1,2-dipropyl vinylene carbonate, vinyl ethylene carbonate (VEC), divinyl ethylene carbonate (DVEC), methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate.

[0074] The present invention has no particular limitation on the type of the separator, and any known porous separator with good chemical and mechanical stability can be selected. According to an embodiment of the present invention, the separator can be made of at least one of glass fiber, non-woven fabric, polyethylene, polypropylene or polyvinylidene fluoride.

[0075] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. If no specific techniques or conditions are specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used that do not specify the manufacturer are all conventional products that can be obtained commercially.

[0076] Example 1

[0077] Calcium carbonate is used as an alkaline substance to separate the positive electrode material and the current collector in the waste lithium battery. The specific steps are as follows:

[0078] (1) Place the waste lithium cobalt oxide battery pack in a saturated NaCl solution and soak for 24 hours to fully discharge it to eliminate the potential risk of combustion or explosion during the disassembly process;

[0079] (2) placing the waste lithium cobalt oxide battery obtained in step (1) in an oven and drying it at 80° C., and then manually disassembling the dried waste lithium cobalt oxide battery to remove the positive electrode sheet;

[0080] (3) Cut the positive electrode sheet obtained in step (2) into pieces with an area of ​​1 cm 2 Then, calcium carbonate 5 times its weight is taken to cover the upper and lower sides of the positive electrode sheet and compacted to obtain a pretreated positive electrode sheet;

[0081] (4) sandwiching the pretreated positive electrode sheet between two sheets of graphite carbon paper, setting the electric pulse parameters, wherein the current size is 140A and the pulse time is 5s, and then performing electric pulse heating treatment to obtain an electric pulse heating product;

[0082] (5) The electric pulse heating product is rinsed with deionized water to obtain a positive electrode sheet, which is placed in an ultrasonic cleaning machine and subjected to cavitation treatment with an ultrasonic power of 40 W for 20 seconds. The ultrasonic cavitation product is filtered to obtain a positive electrode material and a current collector aluminum foil.

[0083] Example 2

[0084] Calcium hydroxide is used as an alkaline substance to separate the positive electrode material and the current collector in the waste lithium battery. The specific steps are as follows:

[0085] (1) Place the waste 811 ternary battery pack in a saturated NaCl solution and soak for 24 hours to fully discharge it to eliminate the potential risk of combustion or explosion during the disassembly process;

[0086] (2) placing the waste 811 ternary battery obtained in step (1) in an oven at 80° C. and then manually disassembling the dried waste 811 ternary battery to remove the positive electrode sheet;

[0087] (3) Cut the positive electrode sheet obtained in step (2) into pieces with an area of ​​1 cm 2 Then, calcium hydroxide 3 times its weight is taken to cover the upper and lower sides of the positive electrode sheet and compacted to obtain a pretreated positive electrode sheet;

[0088] (4) sandwiching the pretreated positive electrode sheet between two sheets of graphite carbon paper, setting the electric pulse parameters, wherein the current size is 130A, the pulse time is 10s, and then performing electric pulse heating treatment to obtain an electric pulse heating product;

[0089] (5) The electric pulse heating product is rinsed with deionized water to obtain a positive electrode sheet, which is placed in an ultrasonic cleaning machine and subjected to cavitation treatment for 30 seconds using an ultrasonic power of 30 W. The ultrasonic cavitation product is filtered to obtain a positive electrode material and a current collector aluminum foil.

[0090] Example 3

[0091] Magnesium carbonate is used as an alkaline substance to separate the positive electrode material and the current collector in the waste lithium battery. The specific steps are as follows:

[0092] (1) Place the waste lithium iron phosphate battery pack in a saturated NaCl solution and soak for 24 hours to fully discharge it to eliminate the potential risk of combustion or explosion during the disassembly process;

[0093] (2) placing the waste lithium iron phosphate battery obtained in step (1) in an oven at 80° C. and drying it, and then manually disassembling the dried waste lithium iron phosphate battery to remove the positive electrode sheet;

[0094] (3) Cut the positive electrode sheet obtained in step (2) into pieces with an area of ​​1 cm2 Then, magnesium carbonate 5 times its weight is weighed and covered on the upper and lower sides of the positive electrode sheet, and compacted to obtain a pretreated positive electrode sheet;

[0095] (4) sandwiching the pretreated positive electrode sheet between two sheets of graphite carbon paper, setting the electric pulse parameters, wherein the current size is 150A and the pulse time is 3s, and then performing electric pulse heating treatment to obtain an electric pulse heating product;

[0096] (5) The electric pulse heating product is rinsed with deionized water to obtain a positive electrode sheet, which is placed in an ultrasonic cleaning machine and subjected to cavitation treatment with an ultrasonic power of 50 W for 10 seconds. The ultrasonic cavitation product is filtered to obtain a positive electrode material and a current collector aluminum foil.

[0097] Example 4

[0098] Sodium hydroxide is used as an alkaline substance to separate the positive electrode material and the current collector in the waste lithium battery. The specific steps are as follows:

[0099] (1) Place the waste lithium manganese oxide battery pack in a saturated NaCl solution and soak for 24 hours to fully discharge it to eliminate the potential risks of combustion or explosion during the disassembly process;

[0100] (2) placing the waste lithium manganese oxide battery obtained in step (1) in an oven and drying it at 80° C., and then manually disassembling the dried waste lithium manganese oxide battery to remove the positive electrode sheet;

[0101] (3) Cut the positive electrode sheet obtained in step (2) into pieces with an area of ​​1 cm 2 Then, 8 times the weight of sodium hydroxide is taken to cover the upper and lower sides of the positive electrode sheet, and compacted to obtain a pretreated positive electrode sheet;

[0102] (4) sandwiching the pretreated positive electrode sheet between two sheets of graphite carbon paper, setting the electric pulse parameters, wherein the current size is 50A and the pulse time is 10s, and then performing electric pulse heating treatment to obtain an electric pulse heating product;

[0103] (5) The electric pulse heating product is rinsed with deionized water to obtain a positive electrode sheet, which is placed in an ultrasonic cleaning machine and subjected to cavitation treatment with an ultrasonic power of 100 W for 5 seconds. The ultrasonic cavitation product is filtered to obtain a positive electrode material and a current collector aluminum foil.

[0104] Example 5

[0105] Magnesium hydroxide is used as an alkaline substance to separate the positive electrode material and the current collector in the waste lithium battery. The specific steps are as follows:

[0106] (1) Place the waste 532 ternary lithium battery pack in a saturated NaCl solution and soak for 24 hours to fully discharge it to eliminate the potential risk of combustion or explosion during the disassembly process;

[0107] (2) placing the waste 532 ternary lithium battery obtained in step (1) in an oven at 80° C. and then manually disassembling the dried waste 532 ternary lithium battery to remove the positive electrode sheet;

[0108] (3) Cut the positive electrode sheet obtained in step (2) into pieces with an area of ​​1 cm 2 Then, magnesium hydroxide 6 times its weight is taken to cover the upper and lower sides of the positive electrode sheet, and compacted to obtain a pretreated positive electrode sheet;

[0109] (4) sandwiching the pretreated positive electrode sheet between two sheets of graphite carbon paper, setting the electric pulse parameters, wherein the current size is 200A and the pulse time is 1s, and then performing electric pulse heating treatment to obtain an electric pulse heating product;

[0110] (5) The electric pulse heating product is rinsed with deionized water to obtain a positive electrode sheet, which is placed in an ultrasonic cleaning machine and subjected to cavitation treatment for 60 seconds using an ultrasonic power of 20 W. The ultrasonic cavitation product is filtered to obtain a positive electrode material and a current collector aluminum foil.

[0111] Example 6

[0112] Calcium oxide is used as an alkaline substance to separate the positive electrode material and the current collector in the waste lithium battery. The specific steps are as follows:

[0113] (1) Place the waste 622 ternary lithium battery pack in a saturated NaCl solution and soak for 24 hours to fully discharge it to eliminate the potential risk of combustion or explosion during the disassembly process;

[0114] (2) placing the waste 622 ternary lithium battery obtained in step (1) in an oven at 80° C. and then manually disassembling the dried waste 622 ternary lithium battery to remove the positive electrode sheet;

[0115] (3) Cut the positive electrode sheet obtained in step (2) into pieces with an area of ​​1 cm 2 Then, calcium oxide 4 times its weight is taken to cover the upper and lower sides of the positive electrode sheet, and compacted to obtain a pretreated positive electrode sheet;

[0116] (4) sandwiching the pretreated positive electrode sheet between two sheets of graphite carbon paper, setting the electric pulse parameters, wherein the current size is 100A and the pulse time is 5s, and then performing electric pulse heating treatment to obtain an electric pulse heating product;

[0117] (5) The electric pulse heating product is rinsed with deionized water to obtain a positive electrode sheet, which is placed in an ultrasonic cleaning machine and subjected to cavitation treatment for 60 seconds using an ultrasonic power of 50 W. The ultrasonic cavitation product is filtered to obtain a positive electrode material and a current collector aluminum foil.

[0118] Example 7

[0119] Sodium oxide and magnesium oxide are used as alkaline substances to separate the positive electrode material and the current collector in the waste lithium battery. The specific steps are as follows:

[0120] (1) Place the waste 811 ternary lithium battery pack in a saturated NaCl solution and soak for 24 hours to fully discharge it to eliminate the potential risk of combustion or explosion during the disassembly process;

[0121] (2) placing the waste 811 ternary lithium battery obtained in step (1) in an oven and drying it at 80° C., and then manually disassembling the dried waste 811 ternary lithium battery to remove the positive electrode sheet;

[0122] (3) Cut the positive electrode sheet obtained in step (2) into pieces with an area of ​​1 cm 2 Then take 1 times the weight of sodium oxide and 1 times the weight of magnesium oxide, cover the upper and lower sides of the positive electrode sheet respectively, and compact them to obtain a pretreated positive electrode sheet;

[0123] (4) sandwiching the pretreated positive electrode sheet between two sheets of graphite carbon paper, setting the electric pulse parameters, wherein the current size is 150A and the pulse time is 5s, and then performing electric pulse heating treatment to obtain an electric pulse heating product;

[0124] (5) The electric pulse heating product is rinsed with deionized water to obtain a positive electrode sheet, which is placed in an ultrasonic cleaning machine and subjected to cavitation treatment with an ultrasonic power of 40 W for 50 seconds. The ultrasonic cavitation product is filtered to obtain a positive electrode material and a current collector aluminum foil.

[0125] Comparative Example 1

[0126] The positive electrode material and the current collector in the waste lithium battery are separated according to the method of Example 1, except that no alkaline substance is added. The specific steps are as follows:

[0127] (1) Place the waste lithium cobalt oxide battery pack in a saturated NaCl solution and soak for 24 hours to fully discharge it to eliminate the potential risk of combustion or explosion during the disassembly process;

[0128] (2) placing the waste lithium cobalt oxide battery obtained in step (1) in an oven and drying it at 80° C., and then manually disassembling the dried waste lithium cobalt oxide battery to remove the positive electrode sheet;

[0129] (3) Cut the positive electrode sheet obtained in step (2) into pieces with an area of ​​1 cm2 A square is formed to obtain a pre-treated positive electrode sheet;

[0130] (4) sandwiching the pretreated positive electrode sheet between two sheets of graphite carbon paper, setting the electric pulse parameters, wherein the current size is 140A and the pulse time is 5s, and then performing electric pulse heating treatment to obtain an electric pulse heating product;

[0131] (5) The electric pulse heating product is rinsed with deionized water to obtain a positive electrode sheet, which is placed in an ultrasonic cleaning machine and subjected to cavitation treatment with an ultrasonic power of 40 W for 20 seconds. The ultrasonic cavitation product is filtered to obtain a positive electrode material and a current collector aluminum foil.

[0132] Test experiment

[0133] 1. The separation efficiency of the positive electrode material and the aluminum foil in Examples 1-7 and Comparative Example 1 was determined. The specific process is as follows:

[0134] The positive electrode powder after ultrasonic separation was placed in an oven at 60°C and dried for 12 hours and then weighed. The formula R(%) = W 1 / W 2 ×100% to calculate the separation efficiency of the positive electrode powder, where R is the separation efficiency (%), W 1 W is the weight of the positive electrode powder obtained by stripping. 2 is the theoretical weight of the positive electrode powder.

[0135] 2. Determine the heat loss of lithium element in the positive electrode materials obtained in Examples 1-7 and Comparative Example 1. The specific process is as follows:

[0136] The positive electrode powder obtained by stripping was immersed in aqua regia for digestion, and then the lithium ion concentration in the digestion solution was tested by inductively coupled plasma-optical emission spectrometry. The formula η(%) = n 1 / n 2 ×100% to calculate the lithium heat loss before and after heat treatment, where η is the heat loss rate efficiency (%), n 1 The lithium content in the positive electrode powder obtained by stripping is n 2 is the theoretical lithium content of the positive electrode powder.

[0137] 3. Determine the fluorine content in the positive electrode materials obtained in Examples 1-7 and Comparative Example 1. The specific process is as follows:

[0138] The fluorine content in waste lithium battery powder is tested using oxygen bomb combustion-ion chromatography. The weighed powder sample is first placed in an oxygen bomb and burned in a high-pressure oxygen environment to generate gas products. The generated gas is captured by an absorption liquid to capture fluoride, and then the capture liquid is treated and injected into an ion chromatograph for analysis to determine the concentration of fluoride ions and calculate the fluorine content in the sample based on the standard curve.

[0139] The experimental results are shown in Table 1. In the separation process of waste lithium battery positive electrode materials and current collectors, compared with the electric pulse heating treatment without the addition of alkaline substances, the introduction of solid alkaline substances can significantly improve the separation efficiency, while reducing the heat loss of lithium elements and the residual fluorine elements in the positive electrode materials. Specifically, after adding alkaline substances, the separation efficiency can be stably reached above 90%, the heat loss of lithium elements can be reduced to below 1.7%, and the fluorine content can be reduced to below 1.5%. These improvements not only optimize the separation effect, but also provide quality assurance for the recycling of positive electrode materials.

[0140] Table 1

[0141] Separation efficiency / % Heat loss of lithium element / % Fluorine content / wt.% Example 1 98.1 1.2 0.7 Example 2 98.5 0.94 0.8 Example 3 97.6 1.5 0.9 Example 4 98 0.91 0.8 Example 5 94.1 0.42 1.5 Example 6 96.4 1.1 1.3 Example 7 95.8 1.7 1.2 Comparative Example 1 2.5 1.8 3.7

[0142] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0143] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for separating positive electrode materials and current collectors in waste lithium batteries, characterized in that: include: The positive electrode sheet and the alkaline substance are subjected to electric pulse heating treatment to obtain the positive electrode material and the current collector; The alkaline substance includes one or more of oxides, hydroxides, carbonates or peroxides of potassium, calcium, sodium, magnesium or aluminum.

2. The method according to claim 1, characterized in that The alkaline substance covers at least a portion of the surface of both sides of the positive electrode sheet.

3. The method according to claim 2, characterized in that The alkaline substance includes one or more of calcium carbonate, calcium hydroxide, magnesium carbonate, sodium hydroxide, magnesium hydroxide, calcium oxide, sodium oxide, and magnesium oxide; Optionally, the alkaline substances covered on both sides of the positive electrode sheet may be the same or different; Optionally, the positive electrode sheet with both sides covered with the alkaline substance is placed between graphite carriers and then subjected to the electric pulse heating treatment.

4. The method according to claim 3, characterized in that The mass ratio of the alkaline substance to the positive electrode sheet is (1-10):

1.

5. The method according to claim 3, characterized in that: The current of the electric pulse heating treatment is 50A-200A; Optionally, the electric pulse heating treatment lasts for 1s-10s.

6. The method according to claim 1, characterized in that After the electric pulse heating treatment, the method further includes: subjecting the product of the electric pulse heating treatment to ultrasonic cavitation treatment to obtain the positive electrode material and the current collector.

7. The method according to claim 6, characterized in that The power of the ultrasonic cavitation treatment is 20w-100w; Optionally, the ultrasonic cavitation treatment time is 5s-60s.

8. The method according to claim 1, characterized in that The waste lithium batteries include one or more of lithium cobalt oxide batteries, ternary lithium batteries, lithium iron phosphate batteries or lithium manganese oxide batteries.

9. A regenerated positive electrode material, characterized in that: The method is separated from waste lithium batteries by the method described in any one of claims 1 to 8.

10. A battery, characterized in that: Including the regenerated positive electrode material as described in claim 9.

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