Method for separating cathode material and current collector in spent lithium battery

Abstract

The application 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: subjecting a positive electrode sheet to an electric pulse heating treatment with 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. Thus, the electric pulse heating technology can quickly and non-destructively separate the positive electrode material from the aluminum foil current collector, and the alkaline substance is used as an auxiliary medium in the electric pulse heating process, which 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, so that the deep defluorination of the positive electrode material of the waste lithium battery is realized.

Description

Technical Field

[0001] This invention relates to the field of lithium battery recycling technology, specifically to a method for separating the positive electrode material and current collector from waste lithium batteries, and to regenerating the positive electrode material and the battery. Background Technology

[0002] In recent years, the lithium-ion battery industry has developed rapidly. Due to its high energy density, long cycle life, and lack of memory effect, lithium-ion batteries are widely used in 3C electronic products, electric vehicles, and chemical energy storage, making them a current research hotspot in the new energy field. With the rapid growth in the application and demand for lithium-ion batteries, a large number of end-of-life batteries will be generated. It is estimated that by 2030, more than 1,100 tons of retired lithium-ion batteries will be produced. Environmental problems and resource recycling issues will also arise as a result.

[0003] The general recycling process for spent lithium-ion batteries is as follows: discharge treatment - disassembly treatment - separation of active materials from aluminum foil - dissolution treatment - resynthesis of new materials. Among these, the separation of active materials from aluminum foil is a key step in achieving efficient lithium-ion battery recycling. Because the adhesion between graphite particles in the negative electrode and copper foil is relatively low, graphite in spent lithium-ion batteries can be easily recycled through mechanical processing. In contrast, the more valuable positive electrode material and aluminum foil are tightly bonded together by polyvinylidene fluoride (PVDF), making them difficult to separate and recycle using traditional methods.

[0004] Therefore, there is an urgent need to develop a separation method that is low in energy consumption, highly efficient, and can effectively control fluorine pollution, so as to achieve non-destructive stripping of various types of waste lithium-ion battery cathode materials. Summary of the Invention

[0005] This invention aims to at least partially solve at least one of the technical problems existing in the prior art. To this end, this invention provides a method for separating the positive electrode material and current collector from waste lithium batteries using electrothermal technology. This method uses an alkaline substance as an auxiliary medium and performs heat treatment under an instantaneous high-temperature environment, which can separate the positive electrode sheet of waste lithium-ion batteries into the positive electrode material and the current collector aluminum foil, while simultaneously capturing the organic fluorine components in the positive electrode material of the waste lithium battery.

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

[0007] During the experiment, the inventors unexpectedly discovered that using electric pulse heating technology could rapidly and non-destructively peel the positive electrode material from the current collector aluminum foil. Simultaneously, using an alkaline substance as an auxiliary medium in the electric pulse heating process not only improved the separation efficiency of the positive electrode material and the current collector but also effectively captured the fluorine-containing components in the positive electrode sheet, achieving deep defluorination of waste lithium battery positive electrode materials. Specifically, the introduction of the alkaline substance effectively buffered the heat conduction of the positive electrode sheet, preventing the high-temperature phase transition of the low-melting-point aluminum foil and inhibiting the aluminothermic reduction reaction between elemental aluminum and the positive electrode material. Furthermore, the thermal insulation effect of the alkaline substance helped protect the crystal structure and chemical composition of the positive electrode material, reducing heat loss and allowing the separated positive electrode material to be directly used for remediation or extraction of valuable metals. In addition, the addition of the alkaline substance increased 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 embodiments 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 is used to cover at least a portion of the surface on both sides of the positive electrode.

[0010] According to 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.

[0011] According to an embodiment of the present invention, the alkaline substances covering both sides of the positive electrode can be the same or different.

[0012] According to an embodiment of the present invention, after the positive electrode sheet covered with the alkaline substance on both sides is placed between the graphite carrier, the electric pulse heating treatment is performed.

[0013] According to an embodiment of the present invention, the mass ratio of the alkaline substance to the positive electrode 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 duration 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 process further includes: subjecting the electric pulse heating treatment product 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 lithium cobalt oxide batteries, ternary lithium batteries, lithium iron phosphate batteries, or lithium manganese oxide batteries.

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

[0021] In a third aspect, the present invention provides a battery. According to an embodiment of the present invention, the battery comprises the recycled 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 from the current collector aluminum foil in waste lithium batteries, ensuring that the peeled positive electrode material retains its original performance and structure, making its key performance indicators such as charge / discharge capacity and voltage platform similar to those of the original material. This ensures that the battery prepared from it has good energy storage and release capabilities, can meet the basic requirements of battery performance in different application scenarios, and can improve resource utilization efficiency, reduce over-exploitation of natural resources, and reduce costs.

[0022] Beneficial effects:

[0023] 1. This invention employs a combination of electric pulse heating and ultrasonic cavitation technology to achieve rapid and non-destructive peeling of the cathode material from a highly reactive current collector (aluminum foil). The electric pulse heating device in this invention can rapidly heat the raw material from room temperature to a high temperature of 1000~3000℃ within seconds. This transient high-temperature treatment can completely destroy the chemical structure of polyvinylidene fluoride without affecting the crystal structure of the cathode material, and minimizes the thermal volatilization loss of lithium in the cathode material. Furthermore, by treating the product after thermal shock with low-power ultrasonic cavitation, the cathode material can be efficiently separated from the aluminum foil, and the cathode material maintains good performance and structural integrity, which can be directly applied to the remediation or extraction of valuable metals.

[0024] 2. The 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. This invention uses a solid alkaline medium as an auxiliary medium in the electric pulse heating process, effectively buffering the heat conduction of the positive electrode sheet, preventing the high-temperature phase transition of low-melting-point aluminum foil, and suppressing the aluminothermic reduction reaction between elemental aluminum and the positive electrode material. Simultaneously, the alkaline groups of the solid alkaline medium promote the pyrolysis 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 waste lithium battery positive electrode materials.

[0026] 4. The positive electrode material obtained 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 subsequent roasting and regeneration. Even with a simple pyrometallurgical roasting and regeneration process, a regenerated positive electrode material with good electrochemical performance can be obtained.

[0027] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

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

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

[0030] Figure description: 100: alkaline substance; 200: positive electrode plate; 300: alkaline substance. Detailed Implementation

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

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

[0033] For the sake of brevity, this article only discloses some specific numerical ranges. 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, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower 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 one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the invention, are intended to cover non-exclusive inclusion.

[0035] In this document, the terms “comprising” or “including” are open-ended expressions, meaning that they include the contents specified in this invention, but do not exclude other aspects.

[0036] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0037] Removing the cathode material from waste lithium-ion battery cathode sheets is a necessary pretreatment step for subsequent resource recycling. However, the cathode material is firmly fixed to a highly chemically active aluminum foil carrier by organic binders (such as polyvinylidene fluoride), making the green and efficient removal of the cathode material a challenge in the pretreatment process. Research has begun on using methods such as low-temperature pyrolysis, reagent dissolution, and mechanochemical separation to separate the cathode material from the current collector aluminum foil. Although these methods can break the adhesive force of the organic binder and achieve separation of the cathode material from the current collector in waste lithium-ion batteries, they suffer from problems such as long processing time, complex process flow, inability to completely decompose the organic binder, and the presence of residual polyvinylidene fluoride between the obtained cathode material particles. This can lead to particle agglomeration and may generate fluorine-containing pollutants during subsequent remediation or metal extraction processes.

[0038] In view of this, the inventors, through extensive experimentation, developed a low-energy-consumption, high-efficiency separation method that effectively controls fluoride pollution. This method uses an alkaline substance as an auxiliary medium and employs electric pulse heating technology to separate the positive electrode material and current collector from waste lithium batteries. This method not only achieves non-destructive stripping of the positive electrode material from waste lithium batteries, achieving a separation efficiency of over 90% between the positive electrode material and the current collector aluminum foil, but also preserves the crystal structure of the positive electrode material and minimizes the thermal volatilization loss of lithium elements in the positive electrode material. Furthermore, this method can effectively capture fluoride-containing components in the positive electrode sheet, achieving deep defluorination of the positive electrode material from waste lithium batteries, thereby effectively controlling fluoride pollution. The following will provide a detailed introduction to the method for separating the positive electrode material and aluminum foil from waste lithium batteries, as well as the regenerated positive electrode material and the battery itself.

[0039] Methods for separating positive electrode materials and aluminum foil from waste lithium batteries

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

[0041] During the experiment, the inventors unexpectedly discovered that electric pulse heating technology could rapidly and non-destructively peel the cathode material from the current collector. Simultaneously, using an alkaline substance as an auxiliary medium in the electric pulse heating process not only improved the separation efficiency of the cathode material and the current collector but also effectively captured the fluorine-containing components in the cathode sheet, achieving deep defluorination of waste lithium battery cathode materials. Specifically, the introduction of the alkaline substance effectively buffered the heat conduction of the cathode sheet, preventing the high-temperature phase transition of the low-melting-point current collector aluminum foil and inhibiting the aluminothermic reduction reaction between elemental aluminum and the cathode material. Furthermore, the thermal insulation effect of the alkaline substance helped protect the crystal structure and chemical composition of the cathode material, reducing heat loss and allowing the separated cathode material to be directly used for remediation or extraction of valuable metals. In addition, the addition of the alkaline substance increased 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 is made to Figure 1The alkaline substance is applied to at least a portion of the surface on both sides of the positive electrode sheet. Here, 100 and 300 represent the alkaline substance, and 200 represents the positive electrode sheet. This alkaline substance not only improves the separation efficiency of the positive electrode material and current collector in waste lithium batteries, but also provides good thermal insulation, effectively buffering the heat conduction of the positive electrode sheet, preventing the high-temperature phase transition of low-melting-point aluminum foil, and inhibiting the aluminothermic reduction reaction between elemental aluminum and the positive electrode material. Furthermore, the alkaline groups of the solid alkaline medium promote the pyrolysis of the organic binder polyvinylidene fluoride, thereby capturing the fluorine-containing components in the positive electrode sheet and achieving deep defluorination of the waste lithium battery positive electrode material.

[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. Therefore, the above-mentioned alkaline substances can improve the contact rate between the alkaline group donor and the organic binder polyvinylidene fluoride, promoting the thermal defluorination reaction. Simultaneously, it avoids heat loss due to the crystal structure and chemical composition of the cathode material.

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

[0045] In some embodiments of the present invention, a positive electrode sheet coated with an alkaline substance on both sides is placed between graphite supports before undergoing the aforementioned electric pulse heating treatment. Thus, the graphite support, on the one hand, can uniformly transmit the electric pulse current to all parts of the positive electrode sheet, forming a uniform electric field on the positive electrode sheet, ensuring uniform heat generation during the electric pulse heating process, avoiding localized overheating or insufficient heating, thereby improving the uniformity and consistency of the separation effect; on the other hand, it acts as a buffer, protecting the positive electrode sheet from direct damage at high temperatures, reducing material structural 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, after placing a positive electrode sheet covered with an alkaline substance on both sides between two sheets of carbon paper, the aforementioned electrical 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, or any range of the above values. Therefore, by keeping the mass ratio of the alkaline substance to the positive electrode sheet within the above range, the separation rate of the positive electrode material and the current collector can be better improved, as well as the contact rate between the alkaline group donor and the organic binder polyvinylidene fluoride (PVDF), 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 calcium carbonate and magnesium carbonate to the positive electrode is (2-7):1. For example, it can be 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, etc., or it can be any range of the above values.

[0049] In this invention, calcium carbonate and magnesium carbonate decompose into calcium oxide or magnesium oxide and carbon dioxide, respectively, under high temperature and electrical pulse. This process not only promotes the degradation of the organic binder PVDF, but also effectively treats fluoride pollution. Specifically, calcium carbonate or magnesium carbonate decomposes into calcium oxide (CaO) or magnesium oxide (MgO) and carbon dioxide (CO2) under high temperature and electrical pulse. The calcium ions (CaO) in the generated calcium oxide... 2+ ) or magnesium ions (Mg) in magnesium oxide 2+ The carbon dioxide will adsorb fluorine atoms (F) from PVDF, forming coordinate bonds and promoting the migration of electrons from fluorine atoms to calcium or magnesium ions. This induces PVDF decoupling, forming Ca-F or Mg-F ionic bonds and disrupting the chemical structure of PVDF. Simultaneously, high-temperature carbon dioxide will react with the CH bonds in PVDF monomers through an oxidative dehydrogenation reaction, generating carbon-carbon double bonds, significantly reducing its mechanical properties and heat resistance. The newly formed calcium oxide or magnesium oxide will also adsorb low-polymerization-degree PVDF, further degrading it to form hydrogen fluoride (HF), achieving deep defluorination of waste lithium battery cathode 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 is (1-5):1. For example, it can be 1:1, 2:1, 3:1, 4:1, 5:1, etc., or it can be any range 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 is (6-10):1. For example, it can be 6:1, 7:1, 8:1, 9:1, 10:1, etc., or it can be any range 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 magnesium hydroxide to the positive electrode is (4-8):1. For example, it can be 4:1, 5:1, 6:1, 7:1, 8:1, etc., or it can be any range of the above values.

[0053] In this invention, calcium hydroxide, sodium hydroxide, or magnesium hydroxide decomposes into calcium oxide, sodium oxide, or magnesium oxide, and water under high temperature and electrical pulse. This process not only promotes the degradation of the organic binder PVDF but also effectively inhibits the aluminothermic reduction reaction between the cathode material and the aluminum foil. Specifically, calcium hydroxide, sodium hydroxide, or magnesium hydroxide decomposes into calcium oxide (CaO), sodium oxide (Na2O), or magnesium oxide (MgO), and water (H2O) under high temperature and electrical pulse. The calcium ions (CaO) in the generated calcium oxide... 2+ Sodium ions (Na+) in sodium oxide + ) or magnesium ions (Mg) in magnesium oxide 2+ The fluorine atom (F) in the PVDF will adsorb and form a coordinate bond, causing the electrons of the fluorine atom to migrate to calcium, sodium, or magnesium ions. This induces the PVDF to decouple and form Ca-F, Na-F, or Mg-F ionic bonds, thus disrupting the chemical structure of the PVDF. Simultaneously, the enthalpy change during the thermal decomposition of the hydroxide is greater than zero, and the thermal decomposition process absorbs additional heat, avoiding the thermal degradation of the cathode material caused by the aluminothermic reduction reaction.

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

[0056] In this invention, calcium oxide, sodium oxide, or magnesium oxide adsorb fluorine atoms (F) in PVDF under high temperature and electric pulse, forming coordinate bonds. This causes electrons of the fluorine atoms to migrate to calcium, sodium, or magnesium ions, thereby inducing PVDF to decouple and form Ca-F, Na-F, or Mg-F ionic bonds, thus destroying the chemical structure of PVDF.

[0057] It should be noted that in this invention, the electric pulse heating technology utilizes electric pulses to rapidly and selectively heat a low-resistance carbon substrate, completing ultra-high temperature oscillation within seconds, thereby achieving transient thermal shock of the raw material. In some embodiments of this invention, the positive electrode of the carbon paper layer containing the waste lithium battery and the alkaline material are connected to the positive and negative terminals of a power source, respectively. A pulse current is applied to the carbon paper layer, and then, according to Joule's law (… Q = I 2 Rt It converts electrical energy into heat energy and controls the thermal shock temperature of waste lithium battery positive electrode sheets by adjusting the current magnitude and the duration of the electrical 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 any range of the above 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 any range of the above values. Therefore, by keeping the conditions of the electric pulse heating treatment within the above range, the chemical structure of the organic binder can be completely destroyed without changing the crystal structure of the cathode material, and the thermal loss and volatilization of lithium in the cathode material is reduced, achieving efficient separation of the cathode material and the current collector.

[0059] In some embodiments of the present invention, after the electropulse heating treatment, the process further includes: subjecting the electropulse heating treatment product to ultrasonic cavitation treatment to obtain the positive electrode material and the current collector. According to embodiments of the present invention, the power of the ultrasonic cavitation treatment is 20W-100W, for example, 20W, 40W, 60W, 80W, 100W, or any range of the above values. According to embodiments of the present invention, the time of the ultrasonic cavitation treatment is 5s-60s, for example, 5s, 10s, 20s, 30s, 40s, 50s, 60s, or any range of the above values. Therefore, 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: immersing waste lithium batteries in a sodium chloride solution; drying the immersed waste lithium batteries; and manually disassembling the dried waste lithium batteries to obtain the positive electrode sheet. This method yields a safe and hazard-free positive electrode sheet.

[0061] It should be noted that this invention does not specifically limit the type of waste lithium battery, as long as the waste lithium battery has a positive electrode material, a current collector, and an organic binder. In some embodiments of this invention, the waste lithium battery can be, but is 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 this invention, the current collector can be aluminum foil, and the organic binder can 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] Regenerated cathode materials and batteries

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

[0064] In a third aspect, the present invention provides a battery. According to an embodiment of the present invention, the battery comprises the recycled 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 from the current collector aluminum foil in waste lithium batteries, ensuring that the peeled positive electrode material retains its original performance and structure, making its key performance indicators such as charge / discharge capacity and voltage platform similar to those of the original material. This ensures that the battery prepared from it has good energy storage and release capabilities, can meet the basic requirements of battery performance in different application scenarios, and can improve resource utilization efficiency, reduce over-exploitation of natural resources, and reduce costs.

[0065] Typically, a battery cell includes a positive electrode, a negative electrode, a separator, and an electrolyte. During charging and discharging, active metal ions repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, serves as a barrier. The electrolyte, acting as a conductor for the active metal ions, lies between the positive and negative electrodes.

[0066] In some embodiments of the present invention, the positive electrode sheet includes a positive current collector and a positive active material layer disposed on at least one side surface of the positive current collector, the positive active material layer including 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 substrate and a metal layer formed on at least one surface of the polymer material substrate. 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), etc.).

[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, the negative electrode active material layer including 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, copper foil may be used as the metal foil. The composite current collector may include a polymer material substrate 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 known in the art for use in batteries. 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, nano-carbon, elemental silicon, silicon oxide, silicon-carbon composite, silicon alloy, elemental tin, tin oxide, tin-carbon composite, tin alloy, and lithium titanate.

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

[0072] For example, the lithium salt includes at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, bis(trifluoromethanesulfonyl)methyl lithium, and tri(trifluoromethanesulfonyl)methyl lithium.

[0073] Exemplarily, the solvent includes at least one of ethylene carbonate (EC), propylene carbonate (PC), butyl carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl ethyl carbonate (EMC), methyl propyl carbonate, ethyl propyl carbonate, ethylene carbonate, vinyl carbonate (VC), methyl vinyl carbonate, 1,2-dimethyl vinyl carbonate, ethyl vinyl carbonate, 1,2-diethyl vinyl carbonate, propyl vinyl carbonate, 1,2-dipropyl vinyl 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] This invention does not impose any particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected. According to embodiments of this invention, the separator membrane material may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, or polyvinylidene fluoride.

[0075] The embodiments of the present invention are described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0076] Example 1

[0077] The positive electrode material and current collector in waste lithium batteries are separated using calcium carbonate as an alkaline substance. The specific steps are as follows:

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

[0079] (2) Place the waste lithium cobalt oxide battery obtained in step (1) in an oven and dry it at 80°C. Then, manually disassemble the dried waste lithium cobalt oxide battery and remove the positive electrode sheet.

[0080] (3) Cut the positive electrode sheet obtained in step (2) into pieces with an area of ​​1 cm². 2 The positive electrode sheet is square, and then five times its weight of calcium carbonate is used to cover the top and bottom sides of the positive electrode sheet and compacted to obtain a pretreated positive electrode sheet.

[0081] (4) The pretreated positive electrode is sandwiched between two sheets of graphite carbon paper. The electrical pulse parameters are set, with the current being 140 A and the pulse time being 5 s. Then, electrical pulse heating is performed to obtain the electrical pulse heating product.

[0082] (5) After rinsing the product heated by electric pulse with deionized water, a positive electrode sheet is obtained. The positive electrode sheet is placed in an ultrasonic cleaner and cavitation is performed with 40 W ultrasonic power for 20 s. After filtering the ultrasonic cavitation product, positive electrode material and current collector aluminum foil are obtained.

[0083] Example 2

[0084] The positive electrode material and current collector in waste lithium batteries are separated using calcium hydroxide as an alkaline substance. The specific steps are as follows:

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

[0086] (2) Place the waste 811 ternary batteries obtained in step (1) in an oven and dry them at 80°C. Then, manually disassemble the dried waste 811 ternary batteries and remove the positive electrode.

[0087] (3) Cut the positive electrode sheet obtained in step (2) into pieces with an area of ​​1 cm². 2 A square is formed, and then calcium hydroxide, three times its weight, is taken and covered on the top and bottom sides of the positive electrode sheet and compacted to obtain a pretreated positive electrode sheet.

[0088] (4) The pretreated positive electrode is sandwiched between two sheets of graphite carbon paper. The electrical pulse parameters are set, with the current being 130 A and the pulse time being 10 s. Then, electrical pulse heating is performed to obtain the electrical pulse heating product.

[0089] (5) After rinsing the product heated by electric pulse with deionized water, a positive electrode sheet is obtained. The positive electrode sheet is placed in an ultrasonic cleaner and cavitation is performed with 30 W ultrasonic power for 30 s. After filtering the ultrasonic cavitation product, positive electrode material and current collector aluminum foil are obtained.

[0090] Example 3

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

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

[0093] (2) Place the waste lithium iron phosphate battery obtained in step (1) in an oven and dry it at 80°C. Then, manually disassemble the dried waste lithium iron phosphate battery and remove the positive electrode.

[0094] (3) Cut the positive electrode sheet obtained in step (2) into pieces with an area of ​​1 cm². 2 The positive electrode sheet is square, and then five times its weight of magnesium carbonate is weighed and covered on the top and bottom sides of the positive electrode sheet, and compacted to obtain a pretreated positive electrode sheet.

[0095] (4) The pretreated positive electrode is sandwiched between two sheets of graphite carbon paper. The electrical pulse parameters are set, with the current being 150 A and the pulse time being 3 s. Then, electrical pulse heating is performed to obtain the electrical pulse heating product.

[0096] (5) After rinsing the product heated by electric pulse with deionized water, a positive electrode sheet is obtained. The positive electrode sheet is placed in an ultrasonic cleaner and cavitation is performed with 50 W ultrasonic power for 10 s. After filtering the ultrasonic cavitation product, a positive electrode material and a current collector aluminum foil are obtained.

[0097] Example 4

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

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

[0100] (2) Place the waste lithium manganese oxide battery obtained in step (1) in an oven and dry it at 80°C. Then, manually disassemble the dried waste lithium manganese oxide battery and remove the positive electrode.

[0101] (3) Cut the positive electrode sheet obtained in step (2) into pieces with an area of ​​1 cm². 2 The positive electrode sheet is square, and then eight times its weight of sodium hydroxide is used to cover the top and bottom sides of the positive electrode sheet and compacted to obtain a pretreated positive electrode sheet.

[0102] (4) The pretreated positive electrode is sandwiched between two sheets of graphite carbon paper. The electrical pulse parameters are set, with the current being 50A and the pulse time being 10 s. Then, electrical pulse heating is performed to obtain the electrical pulse heating product.

[0103] (5) After rinsing the product heated by electric pulse with deionized water, a positive electrode sheet is obtained. The positive electrode sheet is placed in an ultrasonic cleaner and cavitation is performed with 100W ultrasonic power for 5 s. After filtering the ultrasonic cavitation product, the positive electrode material and current collector aluminum foil are obtained.

[0104] Example 5

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

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

[0107] (2) Place the waste 532 ternary lithium battery obtained in step (1) in an oven and dry it at 80°C. Then, manually disassemble the dried waste 532 ternary lithium battery and remove the positive electrode sheet.

[0108] (3) Cut the positive electrode sheet obtained in step (2) into pieces with an area of ​​1 cm². 2 A square shape is formed, and then magnesium hydroxide, which is 6 times its weight, is placed on the top and bottom sides of the positive electrode and compacted to obtain a pretreated positive electrode.

[0109] (4) The pretreated positive electrode is sandwiched between two sheets of graphite carbon paper. The electrical pulse parameters are set, with the current being 200 A and the pulse time being 1 s. Then, electrical pulse heating is performed to obtain the electrical pulse heating product.

[0110] (5) After rinsing the product heated by electric pulse with deionized water, a positive electrode sheet is obtained. The positive electrode sheet is placed in an ultrasonic cleaner and cavitation is performed with 20W ultrasonic power for 60 s. After filtering the ultrasonic cavitation product, positive electrode material and current collector aluminum foil are obtained.

[0111] Example 6

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

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

[0114] (2) Place the waste 622 ternary lithium battery obtained in step (1) in an oven and dry it at 80°C. Then, manually disassemble the dried waste 622 ternary lithium battery and remove the positive electrode.

[0115] (3) Cut the positive electrode sheet obtained in step (2) into pieces with an area of ​​1 cm². 2 A square is formed, and then four times its weight of calcium oxide is taken and covered on the top and bottom sides of the positive electrode sheet, and compacted to obtain a pretreated positive electrode sheet.

[0116] (4) The pretreated positive electrode is sandwiched between two sheets of graphite carbon paper. The electrical pulse parameters are set, with the current being 100 A and the pulse time being 5 s. Then, electrical pulse heating is performed to obtain the electrical pulse heating product.

[0117] (5) After rinsing the product heated by electric pulse with deionized water, a positive electrode sheet is obtained. The positive electrode sheet is placed in an ultrasonic cleaner and cavitation is performed with 50W ultrasonic power for 60 s. After filtering the ultrasonic cavitation product, positive electrode material and current collector aluminum foil are obtained.

[0118] Example 7

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

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

[0121] (2) Place the waste 811 ternary lithium battery obtained in step (1) in an oven and dry it at 80°C. Then, manually disassemble the dried waste 811 ternary lithium battery and remove the positive electrode.

[0122] (3) Cut the positive electrode sheet obtained in step (2) into pieces with an area of ​​1 cm². 2 Take a square shape, then take sodium oxide and magnesium oxide of equal weight, cover the top and bottom sides of the positive electrode sheet respectively, and compact them to obtain a pretreated positive electrode sheet.

[0123] (4) The pretreated positive electrode is sandwiched between two sheets of graphite carbon paper. The electrical pulse parameters are set, with the current being 150 A and the pulse duration being 5 s. Then, electrical pulse heating is performed to obtain the electrical pulse heating product.

[0124] (5) After rinsing the product heated by electric pulse with deionized water, a positive electrode sheet is obtained. The positive electrode sheet is placed in an ultrasonic cleaner and cavitation is performed with 40W ultrasonic power for 50 s. After filtering the ultrasonic cavitation product, positive electrode material and current collector aluminum foil are obtained.

[0125] Comparative Example 1

[0126] The positive electrode material and current collector in waste lithium batteries are separated according to the method in 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 it for 24 hours to fully discharge it in order to eliminate the risk of combustion or explosion during the dismantling process;

[0128] (2) Place the waste lithium cobalt oxide battery obtained in step (1) in an oven and dry it at 80°C. Then, manually disassemble the dried waste lithium cobalt oxide battery and remove the positive electrode sheet.

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

[0130] (4) The pretreated positive electrode is sandwiched between two sheets of graphite carbon paper. The electrical pulse parameters are set, with the current being 140 A and the pulse time being 5 s. Then, electrical pulse heating is performed to obtain the electrical pulse heating product.

[0131] (5) After rinsing the product heated by electric pulse with deionized water, a positive electrode sheet is obtained. The positive electrode sheet is placed in an ultrasonic cleaner and cavitation is performed with 40 W ultrasonic power for 20 s. After filtering the ultrasonic cavitation product, positive electrode material and current collector aluminum foil are obtained.

[0132] Test Experiment

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

[0134] The ultrasonically separated positive electrode powder was dried in a 60℃ oven for 12 hours and then weighed. The formula was used. R (%)= W 1 / W Calculate the separation efficiency of the cathode powder by 2×100%, where R Separation efficiency (%) W 1 represents the weight of the positive electrode powder obtained from the stripping process. W 2 represents the theoretical weight of the positive electrode powder.

[0135] 2. The thermal loss of lithium in the cathode materials obtained in Examples 1-7 and Comparative Example 1 was measured. The specific process is as follows:

[0136] The obtained positive electrode powder was soaked in aqua regia for digestion, and then the lithium ion concentration in the digestion solution was measured by inductively coupled plasma optical emission spectrometry (ICP-OES). The formula η(%) was used. n 1 / n Calculate the lithium heat loss before and after heat treatment using 2 × 100%, where η is the heat loss rate efficiency (%). n 1 represents the lithium content in the cathode powder obtained from the stripping process. n 2 represents the theoretical lithium content of the cathode powder.

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

[0138] The fluorine content in waste lithium battery powder was tested using an oxygen bomb combustion-ion chromatography method. First, the weighed powder sample was loaded into an oxygen bomb and burned under high-pressure oxygen to generate gaseous products. The generated gas was passed through an absorbent to capture fluorides. The collected solution was then treated and injected into an ion chromatograph for analysis to determine the concentration of fluoride ions. The fluorine content in the sample was calculated based on a standard curve.

[0139] The experimental results are shown in Table 1. In the separation process of waste lithium-ion battery cathode materials and current collectors, compared with electro-pulse heating treatment without the addition of alkaline substances, the introduction of solid alkaline substances significantly improves the separation efficiency while reducing the thermal loss of lithium and the residual fluorine in the cathode material. Specifically, after adding alkaline substances, the separation efficiency can stably reach over 90%, the thermal loss of lithium 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 cathode materials.

[0140] Table 1

[0141]

[0142] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0143] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for separating the positive electrode material and the current collector in waste lithium batteries, characterized in that, include: A solid alkaline substance is coated on both sides of the positive electrode sheet, followed by electric pulse heating treatment. The product of the electric pulse heating treatment is then subjected to ultrasonic cavitation treatment to obtain the positive electrode material and the current collector. The solid alkaline substance includes one or more of the following: oxides, hydroxides, and carbonates of potassium, calcium, sodium, and magnesium. The current for the electric pulse heating treatment is 50A-200A; The duration of the electric pulse heating treatment is 1s-10s.

2. The method according to claim 1, characterized in that, The solid alkaline substance includes one or more of calcium carbonate, calcium hydroxide, magnesium carbonate, sodium hydroxide, magnesium hydroxide, calcium oxide, sodium oxide, and magnesium oxide. The solid alkaline substances covering both sides of the positive electrode can be the same or different; After the positive electrode sheet, which is covered with the solid alkaline material on both sides, is placed between the graphite carriers, the electric pulse heating treatment is performed.

3. The method according to claim 2, characterized in that, The mass ratio of the solid alkaline substance to the positive electrode is (1-10):

1.

4. The method according to claim 1, characterized in that, The power of the ultrasonic cavitation treatment is 20W-100W; The ultrasonic cavitation treatment time is 5s-60s.

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

6. A recycled cathode material, characterized in that, It is obtained by separating from waste lithium batteries using the method described in any one of claims 1-5.

7. A battery, characterized in that, Includes the recycled cathode material as described in claim 6.

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