Method for regenerating lithium-containing energy storage batteries

Abstract

The present invention relates to a method for reprocessing lithium-containing energy storage means, said method comprising at least the following method steps: i) optionally pre-treating said lithium-containing energy storage means, said pre-treatment comprising at least one of thermal, mechanical and electrical pre-treatment; ii) pyrolyzing said optionally pre-treated lithium-containing energy storage means to liberate carbon dioxide and carbonate at least a portion of its contained lithium under a carbon dioxide atmosphere; iii) separating the lithium in a separation step; iv) hydrometallurgically reprocessing the mixture obtained in method step iii) to further carbonate said contained lithium and separate the lithium in a further separation step; and v) returning the carbon dioxide liberated in method step ii) to at least one of method steps ii) and iii).

Description

[Technical Field]

[0001] The present invention relates to a method for reprocessing lithium-containing energy storage means. The present invention relates in particular to a method by which lithium-containing energy storage means, in particular lithium-ion batteries, can be reprocessed or reused. [Background technology]

[0002] Sustainable and resource-efficient operations are becoming increasingly important in all technological fields. Rising levels of electromobility mean that lithium-ion battery reuse is of growing interest and relevance. Battery reuse rates influence the life cycle assessment of electric vehicles. Furthermore, the EU Battery Directive requires a reuse efficiency of 50% by weight. This legal standard is likely to become even stricter in the future. Element recovery rates are also being introduced. To date, established reuse methods have focused on recovering cobalt and nickel due to economic benefits. For example, cobalt, nickel, and manganese constitute up to 80% of the material value of recycled NMC cells (lithium nickel manganese cobalt oxide). However, for cost reasons, cobalt is expected to be largely eliminated or at least minimized in future battery systems (lithium iron phosphate (LFP)-based) or nickel-cobalt aluminum (NCA)-based). Meanwhile, lithium will likely remain the default component of lithium-ion batteries due to its properties, such as low density and lowest standard potential. Therefore, efficient lithium recycling is essential. Economic and geopolitical factors are further drivers for lithium recycling.

[0003] WO 2021 / 226719 describes a hydrometallurgical green chemistry method for recovering one or more metals from a metal-containing material, comprising leaching the metal-containing material with formic acid to obtain a leachate containing the one or more metals as one or more metal formates, and precipitating at least one of the one or more metal formates. The metal-containing material may be a cathode material for a lithium-ion battery, in which case lithium formate remains in solution and salts including one or more of nickel formate, cobalt formate, and manganese formate are precipitated. The steps may include filtering the leachate, sulfiding the remaining metal formate to form metal sulfates, purifying the filtered leachate by adding lithium carbonate and filtering, dehydrating the purified leachate, and thermally decomposing the resulting lithium salt to obtain battery-grade lithium carbonate.

[0004] Chinese Patent Publication No. 109921125 describes a pretreatment method for recycling lithium batteries, which includes the following steps: step 1, disassembling the lithium battery to obtain a cathode plate, an anode plate, a separator, a battery shell, and a cover plate; step 2, pre-grinding the cathode plate and selecting a cathode material and a conductive agent; step 3, heat-treating the cathode material; step 4, mixing an active additive for mechanical grounding into the heat-treated cathode material to activate the cathode material; and step 5, pre-grinding the anode plate, which is then placed in a shaker to separate it, and selecting a metal foil material and a formula.

[0005] Chinese Patent Publication No. 106505271 discloses a method for recycling lithium-ion batteries, which includes the steps of cutting electrode plates removed from lithium-ion batteries into small pieces, gradually heating and warming them in a heating furnace equipped with a gas recovery device, stirring the heated and warmed electrode plates in a sodium hydroxide solution to peel the electrode material from the aluminum foil, directly recycling the aluminum foil and simultaneously recovering the electrode material, washing and drying the electrode material, and uniformly grinding the electrode material in a ball mill, and analyzing the contents of various elements in the electrode material.

[0006] Chinese Patent Publication No. 113921931 relates to a method for recycling lithium carbonate from used lithium-ion batteries, particularly by thermal reduction using carbon. This patent document aims to solve the technical problem of the difficulty of separating the cathode and anode materials in the black powder of used lithium-ion battery waste, making it difficult to recycle lithium resources. This method allows used lithium-ion batteries to be directly destroyed and sorted without discharging, disassembling, or separating them to obtain black powder, thereby maximizing the recycling of lithium from used lithium-ion batteries. At the same time, the nickel, cobalt, and manganese in the filtration residue obtained from the first suction filtration step can be used to prepare precursors or be intentionally recycled.

[0007] However, the solutions known from the prior art still leave room for improvement, especially with regard to the efficient recycling of lithium-containing batteries. Summary of the Invention

[0008] It is therefore an object of the present invention to create a means of at least partially overcoming at least one of the drawbacks of the prior art, in particular to provide a solution that allows for an improved recycling of lithium-containing batteries.

[0009] This object is achieved according to the invention by a method having the features of claims 1 and 2. This object is further achieved by using the method according to the invention for recovering lithium and anode material from lithium-containing energy storage means. Preferred developments of the invention are disclosed in the dependent claims, the description and the drawings, and further features mentioned or shown in the dependent claims or in the description or drawings may, individually or in any desired combination, constitute the subject-matter of the invention, unless the context clearly dictates otherwise.

[0010] The present invention relates to a method for reprocessing lithium-containing energy storage means, said method comprising the following method steps: i) optionally pre-treating the lithium-containing energy storage means, the pre-treatment comprising at least one of thermal, mechanical, and electrical pre-treatment; ii) pyrolyzing the optionally pretreated lithium-containing energy storage means to liberate carbon dioxide and carbonate at least a portion of the contained lithium in a carbon dioxide atmosphere; iii) separating the lithium in a separation step; iv) hydrometallurgically reprocessing the mixture obtained in process step iii) to further carbonate the contained lithium and separate the lithium in a further separation step; and v) returning the carbon dioxide liberated in process step ii) to at least one of process steps ii) and iii), The present invention relates to a method comprising at least

[0011] The present invention relates to a method for reprocessing lithium-containing energy storage means, said method comprising the following method steps: i) optionally pre-treating the lithium-containing energy storage means, the pre-treatment comprising at least one of thermal, mechanical, and electrical pre-treatment; ii) pyrolyzing the optionally pretreated lithium-containing energy storage means to liberate carbon dioxide and carbonate at least a portion of the contained lithium in a carbon dioxide atmosphere; iii) separating the lithium in a separation step; and iv) hydrometallurgically reprocessing the mixture obtained in process step iii) to further carbonate the lithium contained therein and separate the lithium in a further separation step; The present invention relates to a method comprising at least

[0012] The above-described method is therefore useful for the reprocessing of lithium-containing energy storage means. Reprocessing should be interpreted in particular to mean a process that allows the recovery of raw materials contained in said energy storage means. For example, energy storage means typically contain metals or metal compounds that can be used as raw materials for value creation. In particular, the method described here can be used to recover lithium used in energy storage means, but as will be appreciated by those skilled in the art, this method is not limited to obtaining lithium. For example, anode materials such as graphite can also be recovered.

[0013] Therefore, the selection of reprocessed lithium-containing energy storage means is not limited, and lithium and lithium-ion batteries can be used in particular. Due to the expansion of electromobility, the reuse of used lithium-ion batteries is gaining attention. Therefore, the method described herein in particular uses lithium-containing energy storage means that have exceeded their useful life. Such energy storage means are known as "end-of-life" energy storage means. However, in principle, other energy storage means, such as energy storage means with manufacturing defects or damage, can also be used. The advantage of using secondary materials as starting materials for the method described herein is, in particular, that the lithium is more concentrated in the energy storage means than, for example, primary ores. Therefore, extraction is, in principle, simplified and advantageous compared to mining. At the same time, since lithium is currently not sufficiently recycled, the present invention contributes to closed-loop management of battery raw materials. In the present invention, shredded materials, production scrap, cells, modules, and mixtures thereof can be used as lithium-containing energy storage means.

[0014] The method described herein includes at least the following method steps:

[0015] In method step i), the lithium-containing energy storage means is optionally pre-treated, which, if pre-treated, comprises at least one of thermal, mechanical and electrical pre-treatment.

[0016] The purpose of pre-treatment is in particular to prepare the lithium-containing energy storage means used for the remainder of the process and therefore for the actual feedstock recovery, in particular for lithium recovery, and, if necessary, to initiate the separation of part of the feedstock from the lithium-containing product stream, also called "black mass", which typically contains at least the active materials, preferably the cathode and anode active materials, and the corresponding lithium compounds.

[0017] Pretreatment ensures that subsequent process steps can be carried out more efficiently or safely. Plastic components or certain other materials, such as metals, solvents, or reusable WEEE materials (Waste Electrical and Electronic Equipment), can, for example, be removed during pretreatment. For example, cables, control devices, e.g., battery management systems (BMS), or module shells or their components, so-called heavy fractions made of iron or aluminum, or contacts made of copper, can be separated from the lithium-containing product stream to be further processed.

[0018] Thermal, mechanical, and electrical pretreatments are particularly advantageous pretreatments, which may be solely thermal, solely mechanical, solely electrical, or may be a combination of several respective pretreatments, either simultaneously or sequentially.

[0019] In the case of thermal pretreatment, the energy storage means can be particularly thermally inactivated, so that subsequent steps can be carried out without safety concerns. The conductive salt, particularly LiPF6, is preferably decomposed during the thermal pretreatment. The decomposition products of the conductive salt are then available for further transformation in subsequent pyrolysis. Furthermore, organic components or some low-boiling components, preferably solvents, can be volatilized during the thermal pretreatment and then condensed. The electrolyte solvent is preferably volatilized during the thermal pretreatment and condensed for recovery. Thus, the thermal pretreatment can serve both safety purposes and the purpose of initiating the separation of the materials of the energy storage means.

[0020] The mechanical pretreatment may in particular comprise the disassembly of the energy storage means. For example, used energy storage means can be disassembled to the module or cell level to simplify further method steps and, if necessary, remove components such as contacts, shell components, and control devices from the lithium-containing product stream. Furthermore, it is also possible to mechanically destroy, for example shred, the energy storage means while separating the electrolyte, for example under a protective gas atmosphere.

[0021] The electrical pretreatment may preferably include a complete discharge of the energy storage means. This can be achieved purely electrically by normal discharge, or by thermal or mechanical treatment. Discharge offers the advantage that Li ions on the cathode side are inserted into the transition metal oxide. During pyrolysis, the cathode material is decomposed into short-chain components, so that the lithium in the cathode material is more readily available after pyrolysis than the lithium in the anode material. This can therefore improve the lithium yield.

[0022] In accordance with the above, said lithium-containing energy storage means is pretreated according to method step i), which method step i) comprises the following reaction steps: i.1 mechanically disassembling said lithium-containing energy storage means, preferably to module or cell level; i.2 discharging said lithium-containing energy storage means; and i.3 thermal treatment of said energy storage means, preferably disassembled to module and / or cell level, preferably to decompose the conductive salt and volatilize the solvent, said solvent preferably being condensed for recovery, It is particularly preferred to have at least one of the following:

[0023] In a preferred embodiment, the method comprises a thermal pre-treatment of the energy storage means disassembled to module and / or cell level in order to decompose the conductive salt and volatilize the solvent, In method step ii), the shredded material is used as the lithium-containing energy storage means, the shredded material comprising a cathode material and an anode material; and The pretreated lithium-containing energy storage means is destroyed between the thermal pretreatment and method step ii).

[0024] The temperature in the thermal pretreatment is preferably 350°C or less.

[0025] In method step ii), the method further comprises pyrolyzing the optionally pretreated lithium-containing energy storage means to liberate carbon dioxide and carbonate at least a portion of the contained lithium under a carbon dioxide atmosphere. This step may therefore comprise thermal treatment of the optionally pretreated energy storage means, and thus the lithium-containing product stream resulting from the pretreatment. Alternatively, the present invention does not exclude that the treated energy storage means may be directly subjected to thermal treatment or pyrolysis according to method step ii) without pretreatment. Thus, not only product streams from pretreatment, such as shredded material, production scrap, whole cells, or modules, but also untreated energy storage means may be used in method step ii). To enable lithium recovery, it is important that a lithium-containing active material or electrode material of the energy storage means, preferably a cathode material, is used. The lithium-containing energy storage means in method step ii) preferably comprises a cathode material and an anode material. Therefore, preferably, materials containing only small amounts of anode material residues are not used. For example, the lithium-containing energy storage means of method step ii) preferably comprises more than 20% by weight of anode material, particularly preferably more than 20% by weight of graphite. The lithium-containing energy storage means of method step ii) further preferably comprises a conductive salt and / or decomposition products thereof. The lithium-containing energy storage means of method step ii) further preferably comprises a current conductor. In other words, the cathode material, the anode material, the conductive salt, and the current conductor and their decomposition products are preferably not separated before pyrolysis. For pyrolysis, preferably, shredded material having cathode and anode active material powders attached thereto ("powder-coated shredded material") is used.

[0026] In a preferred embodiment, the temperature in process step ii) (pyrolysis) is between 500°C and 700°C.

[0027] This method step serves in particular to at least partially carbonate the lithium contained in the lithium-containing product stream, i.e., to convert lithium compounds present in the battery cell, especially if pretreated, into aqueous lithium carbonate. This allows the lithium carbonate to be subsequently selectively washed off in an aqueous solution without dissolving further components from the active material. Another advantage is the possibility of recovering graphite by combining leaching and flotation processes, as explained in more detail below. Lithium fluoride can then be separated, but is preferably formed during pyrolysis. Therefore, this method is also preferably a method for recovering lithium fluoride from lithium-containing energy storage means.

[0028] To carry out method step ii), a reducing atmosphere is essential so that carbonation can proceed unhindered. A reducing atmosphere can be established by the thermal decomposition of the lithium-containing material, which produces and liberates pure CO2. Active materials include, in principle, materials such as NMC and binders, which also liberate carbon dioxide during thermal decomposition in a reducing atmosphere. Therefore, in this step, it may be advantageous for the lithium-containing active material and binder to also be present as a carbon-containing or organic material, such as PVDF, which has one or more oxygen atoms in its molecular structure.

[0029] In addition to the carbon dioxide obtained, a protective gas, such as argon or nitrogen, can also be fed to this process step. In this process, a suitable atmosphere can be present and does not have to consist solely of carbon dioxide. However, in the present invention, the carbon dioxide obtained is also recycled, as will be explained in more detail below.

[0030] In the method according to the present invention, a carbon dioxide atmosphere, optionally combined with a protective gas such as argon or nitrogen, is preferably used to suppress undesired oxidation reactions. This atmosphere also preferably allows for the separation of lithium fluoride in step iii). Without intending to be bound by this theory, the inventors hypothesize that the carbon dioxide atmosphere forms a protective gas atmosphere. Pyrolysis under a carbon dioxide atmosphere leads to the decomposition of the binder and the decomposition of the long-chain transition metal oxides into simple transition metal oxides, thereby liberating lithium. This thermal decomposition of the raw materials is evident, for example, by the powder coating peeling off from the current conductor foils (aluminum and copper foils). During the pyrolysis of the long-chain transition metal oxides under non-oxidizing conditions, lithium is liberated from the base material. This treatment is carried out on the entire module / cell, still containing the electrolyte and conductive salt residues, resulting in a particularly high yield.

[0031] In a preferred embodiment of the process according to the invention, during said pyrolysis process step ii) and optionally the thermal pretreatment, transition metals such as cobalt, nickel and manganese are not reduced to metallic transition metals.

[0032] After the pyrolysis, the product stream, i.e., the lithium-containing material subjected to pyrolysis, is fed to process step iii). In process step iii), lithium is separated in a first separation step, where separation specifically refers to selective separation of lithium compounds from the remaining mass. This can be achieved, in particular, by leaching the product obtained in the above-mentioned step. In particular, neutral leaching can be carried out in aqueous solution by mixing the product to be treated with water. In this way, lithium can be rinsed off highly selectively in the form of lithium carbonate produced by the above-mentioned thermal carbonation, without involving foreign matter. In this way, lithium carbonate is already separated in a relatively pure form and can then be processed to lithium. In a preferred embodiment, fluorides, in particular lithium fluoride, are also separated in process step iii).

[0033] In particular, neutral leaching is carried out using, for example, only water, which is an advantage over prior art methods that often required the use of acid. The introduction of carbon dioxide into the solution is advantageous in this method because it produces carbonic acid, which can improve the solubility of lithium compounds in aqueous solution and therefore improve the extraction of lithium. In preferred embodiments, the carbon dioxide helps establish a neutral to slightly acidic pH value that facilitates the selective separation of lithium.

[0034] In process step iv), the lithium-depleted mixture obtained in process step iii) is further hydrometallurgically reprocessed. In this process step, any lithium or lithium compounds still present are further carbonated. This step allows for the separation of further substances, in particular metals such as aluminum, iron, cobalt, nickel, manganese, and therefore also the separation of residual lithium. As is generally known in hydrometallurgical processes, the respective metals can be removed by changing the pH and / or by extraction with organic solvents.

[0035] In the methods described herein, method step v) further comprises returning the carbon dioxide liberated in method step ii) to at least one of method steps ii) and iii), for example, the carbon dioxide liberated in method step ii) may be returned only to method step ii), only to method step iii), or to both method steps ii) and iii), or may be directed to further method steps as required.

[0036] The carbon dioxide obtained is fed to process step ii), which serves to create a reducing atmosphere and to provide a reagent for carbonation.

[0037] The supply of carbon dioxide to process step iii) likewise makes it possible to supply a reagent for carbonation and improve the dissolution of the lithium compound in aqueous solution by the formation of carbonic acid.

[0038] In principle, waste gases from the thermal processing of lithium-based energy storage devices could be used for the carbonation of Li compounds and thus represent a focal point for the recovery of lithium as a new raw material, making the CO2 cycle particularly suited to the method developed here and offering significant synergistic benefits.

[0039] For example, in addition to recycling carbon dioxide, it is possible to recycle other, especially gaseous, components, such as protective gases, e.g., argon or nitrogen, obtained in or fed to step ii), which may simply be conducted together with the carbon dioxide or purified and put to suitable use. This also helps to conserve resources and thus improves sustainability.

[0040] As mentioned above, carbon dioxide is used in process step ii) to carry out the carbonation of lithium. For this purpose, it is advantageous to add carbon dioxide to process step ii). Recycling the carbon dioxide obtained means that the addition of fresh carbon dioxide, if necessary, can be omitted or at least significantly reduced. Furthermore, it is possible to prevent the carbon dioxide generated as a waste gas, which is usually released into the environment in prior art processes. Therefore, the process described herein can have clear environmental advantages. Furthermore, the process can be implemented with reduced resource consumption and low cost, which is a particular advantage over prior art solutions. For example, prior art processes for the thermal reuse of lithium-ion batteries generate CO2, which releases this climate-harming greenhouse gas into the environment, which runs counter to efforts to reduce CO2 emissions from industrial processes.

[0041] In particular, in the case of an additional thermal pretreatment according to method step i), carbon dioxide is obtained in a second thermal treatment step by suitable temperature control of the thermal pretreatment according to method step i) and the pyrolysis according to method step ii), whereby the carbon dioxide obtained can be purified and used as desired.

[0042] Therefore, the present invention not only improves lithium yield but also reduces emissions by recycling CO2 without the need for additional additives, such as carbonizing agents, required in conventional methods. This method also saves on additional additives, such as pH adjusters, for further hydrometallurgical processing. Conventional hydrometallurgical processes, based on water and CO2, require large amounts of leaching agents, such as HCl and H2SO4, pH adjusters, such as NaOH or KOH, or oxidizers, such as HO2, because lithium and graphite must be separated beforehand. This results in mass loss, which can be avoided in the present invention.

[0043] By intentionally recycling the carbon dioxide, it becomes available and is converted into products, thereby providing the benefits of thermal pretreatment without the unwanted side effects. It is highly advantageous that the CO2 generated in this process can be utilized as a usable resource for both lithium and graphite through an innovative recycling method.

[0044] It is further preferred that the method further comprises a further process step of flotation, e.g., before process step iv). A preferred embodiment of this method comprises flotation to obtain the anode material. Flotation is preferably carried out after process step iii) and before process step iv). In one embodiment, process step v) is carried out so that at least a portion of the returned carbon dioxide is used in the flotation. Flotation must be carried out in a manner known per se, meaning a physicochemical separation method for particulate solids based on the different surface wettability of the particles. This method is carried out in a liquid, in particular water, and further involves the supply of a gas, e.g., air. Anode materials, in particular graphite, can particularly preferably be removed from the product stream in the development described herein. Graphite is typically present as an anode material in energy storage devices and is a valuable raw material classified as critical by the EU. In the method according to the invention, the anode material preferably comprises graphite.

[0045] If necessary, adding a small amount of additive to the aqueous solution will affect the friction grinding so that the graphite particles float to the surface as bubbles and the metal particles sink. Then, in this method, the bubbles can be skimmed off and the graphite can be separated.

[0046] Isolating the graphite offers a further significant advantage compared to prior art processes that generate CO2 by burning graphite and converting it to CO2 / CO. In contrast, the present invention prevents the loss of important raw materials, along with the production of additional CO2. In a preferred embodiment of the process according to the invention, the graphite is inert.

[0047] In the present development, flotation is particularly preferably carried out using carbon dioxide, since carbon dioxide is generated in situ in the present process, does not interfere with bubble formation or foaming, and is moreover advantageously suitable for bubble formation or foaming.

[0048] Furthermore, the carbon dioxide returned in process step v) is preferably purified before being returned, in particular in at least one of process steps ii) and / or iii) and / or during flotation. This allows for the particular removal of contaminants present in the gas stream. This can be achieved, for example, by means of a filter device capable of removing entrained solids from the gas stream. Additionally or alternatively, gaseous impurities can also be removed from the gas stream using gas separation methods known per se.

[0049] This step allows method step ii) to be carried out particularly efficiently, since no foreign bodies, waste or impurities are reintroduced into the product stream to be treated. Method step ii) of separating the products can therefore be improved with respect to the feeding of undesired foreign bodies, and thereby the purification of the lithium obtained can be improved.

[0050] Furthermore, it is preferred to at least intermittently supply carbon dioxide as fresh gas to process step ii). This development allows for the fact that the returned carbon dioxide may be insufficient to form the atmosphere of process step ii). Fresh or non-returned carbon dioxide can therefore be supplied to process step ii). The addition of fresh gas can be advantageous, particularly during the start-up of the process.

[0051] The source of fresh CO gas is in principle not limited. However, it is advantageous for CO to originate, for example, from a "CC" process, also known as a carbon dioxide carbon capture process, which refers to the capture of carbon dioxide, in particular from waste gases derived from combustion, and its subsequent use in further chemical processes. This development allows further improvements in the environmental aspects and, consequently, the sustainability of the method described herein.

[0052] It may further be preferred that process step ii) is carried out in a continuously operated moving-bed reactor. In particular, this development has shown that recycling the material allows for an effective carbonation of the lithium species, which allows for an effective leaching of the lithium carbonate in a subsequent step, and therefore a particularly effective and impurity-free recovery of lithium.

[0053] However, the process is not limited in principle to continuously operated moving-bed reactors: for the purposes of the present invention, batch processes or other reactors are also possible for carrying out the pyrolysis according to process step ii).

[0054] It is further preferred that process step ii) is carried out at a temperature in the range from 300° C. to 800° C. Process step ii) can preferably be carried out at a temperature in the range from 350° C. to 560° C., for example from 400° C. to 560° C. In particular, this temperature range allows this process step to be carried out in an energy-saving manner. However, it also allows ensuring that an efficient thermal carbonation takes place, so as to ensure that a large amount of the lithium compound is already carbonated and can react to form lithium carbonate.

[0055] In particular, but not exclusively, in this development, the waste gas stream, and therefore in particular the discharged and returned carbon dioxide stream, can be brought to a high temperature, which can likewise be utilized in the method described herein. The waste heat from the carbon dioxide stream leaving the pyrolysis can in principle be utilized to regulate the temperature of further processes, such as lithium carbonate leaching or hydrometallurgy. For this purpose, the hot carbon dioxide can be passed through a heat exchanger, as appropriate, or introduced directly into the process.

[0056] By way of example only, the waste gases can be recycled to the thermal pretreatment to establish a suitable process atmosphere for the deliberate phase transformation in the cathode material, which is particularly advantageous for subsequent processing.

[0057] Furthermore, the product obtained in process step ii) is preferably mechanically treated between process steps ii) and iii). This treatment step may in particular serve to further concentrate the lithium-containing material and thus further improve the treatment of lithium. In particular, this treatment step serves, for example, to separate the aluminum and copper foils and shell parts (if they are still present) from the active material. This can be done, for example, by intensive sieving or impact milling. As will be understood by those skilled in the art, this process step may be carried out as a function of the actual material still present or its amount.

[0058] Preferably, in the method for thermal pretreatment and / or pyrolysis, no solid carbon is added. Particularly preferably, no coal, activated carbon, anthracite, etc. is added for thermal pretreatment and / or pyrolysis.

[0059] In view of the above, the present invention further provides the use of the above-described method for reprocessing lithium-containing energy storage means. In particular, the present invention provides the use of the above-described method for recovering lithium and / or anode material from lithium-containing energy storage means. In other words, the method according to the present invention is preferably a method for recovering lithium and / or anode material from lithium-containing energy storage means.

[0060] As mentioned above, the deliberate recycling of the defined end-of-life products makes the resulting CO2 available and can be converted into products, thereby providing the benefits of thermal pretreatment without the unwanted side effects. It is highly advantageous that the CO2 generated in this way can be utilized as a usable resource for both lithium and graphite through an innovative recycling process. Compared to prior art solutions, this combines good environmental performance with relatively low costs and the possibility of improving the purity of the recovered lithium. This method is therefore cost-effective, environmentally friendly, and allows for an economically viable recovery of lithium and graphite.

[0061] The present invention will now be described by way of example with reference to the accompanying drawings, in which each feature may be individually or in combination as appropriate to form an aspect of the invention as set forth below, and the present invention is not limited to the following drawings, description, and exemplary embodiments. [Brief explanation of the drawings]

[0062] [Figure 1]1 shows a schematic flow chart of an exemplary development of the method according to the invention. Figure 1 is a schematic flow chart of the method according to the invention. This method is used to reprocess lithium-containing energy storage means, thereby recovering in particular the raw materials incorporated therein, in particular lithium. The chart shows the introduction 10 of the lithium-containing energy storage means into the method. DETAILED DESCRIPTION OF THE INVENTION

[0063] The lithium-containing energy storage means is first subjected to an optional pre-treatment 12. This pre-treatment 12 may be, for example, thermal, mechanical and / or electrical and serves in particular to discharge or passivate the energy storage means. The components of the energy storage means may further be subjected to a discharge 14. This discharge 14 makes it possible to remove, for example but not limited to, plastic, metal or electrical components, so that they can be separated from a lithium-containing product stream 16 destined for further processing. Therefore, the pre-treatment 12 preferably comprises at least one of the following method steps: i.1 Mechanical disassembly of lithium-containing energy storage means; i.2 Discharge of lithium-containing energy storage means; and i.3 Thermal treatment of said energy storage means.

[0064] The sent product stream 16, or the optionally pretreated energy storage means, is further subjected to pyrolysis 18, which is preferably operated continuously, for example at a temperature in the range of 300°C to 800°C and / or in a moving-bed reactor. Pyrolysis 18 is carried out under a carbon dioxide atmosphere, thus under reducing conditions, and at least a portion of the lithium contained is carbonated. Materials contained in the product stream, such as in particular the active material and binder components, are further decomposed, and carbon dioxide is obtained or liberated during pyrolysis 18.

[0065] The products obtained during pyrolysis 18 are optionally subjected to mechanical treatment 20. This treatment step may serve in particular to further concentrate the lithium-containing product stream 16 and to further improve the treatment of lithium. In particular, this treatment step serves, for example, to separate, by discharge 22, aluminum and copper foils and shell parts, if still present, from the active material or lithium-containing product stream 16.

[0066] The lithium is then separated 24 in a separation step. This can in particular be carried out by leaching the product obtained in the above step. In particular, neutral leaching can be carried out in an aqueous solution by mixing the product to be treated with water, resulting in the discharge 26 of an aqueous solution containing lithium in the form of lithium carbonate formed as a water-soluble product during thermal decomposition.

[0067] To remove graphite from the lithium-containing product stream 16, the stream is then subjected to a flotation process 28. In particular, a gas such as carbon dioxide may be introduced into the flotation tank or liquid contained therein along with the lithium-containing product stream 16, thereby allowing the graphite to be separated and removed from the lithium-containing product stream 16 by discharge 30.

[0068] The lithium-containing product stream 16 is finally subjected to hydrometallurgical reprocessing 32, in particular further carbonation of the lithium content and separation of the lithium in a further separation step by discharge 34. In addition to lithium, further components, in particular metals, can be discharged by pH conversion and / or extraction methods.

[0069] 1 further shows that the carbon dioxide liberated during pyrolysis 18 is recycled 36 within the cycle and fed to at least one of the process steps of pyrolysis 18 and separation 24. The carbon dioxide may further be fed to a flotation process 28. In principle, it is preferred that the returned or fed carbon dioxide is purified before being returned / fed.

[0070] The recirculation 36 may itself be sufficient to create a suitable atmosphere during pyrolysis 18. However, it may also be necessary to supply 38 carbon dioxide as fresh gas to pyrolysis 18, at least intermittently. Protective gas may additionally or alternatively be supplied to pyrolysis 18, and this gas may likewise be recycled and purified as necessary.

[0071] In a further embodiment, a method for recovering lithium and anode material from a lithium-containing energy storage means is described, wherein the anode material comprises graphite.

[0072] Production scrap, cells, modules, and optionally shredded material may also be used as lithium-containing energy storage means, with the production scrap and modules being broken down to the cell level in this example.

[0073] The lithium-containing energy storage means is first subjected to pretreatment 12. In this pretreatment 12, the energy storage means decomposed to the cell level is thermally pretreated at 350°C or less to decompose the conductive salt and volatilize the solvent. The solvent is condensed and recovered, and the thermally pretreated lithium-containing energy storage means is decomposed and the shredded material is used as the lithium-containing energy storage means in the subsequent thermal decomposition.

[0074] The components of the energy storage means are further subjected to a discharge 14, which makes it possible to remove, for example, plastic, metal or electrical components, thereby separating them from a lithium-containing product stream 16 destined for further processing.

[0075] The product stream 16 or pretreated energy storage means sent to the next step is subjected to a continuously operated pyrolysis 18, for example in a moving-bed reactor at a temperature in the range of 500°C to 800°C. Prior to pyrolysis, the anode and cathode materials are not separated; instead, the product stream 16 or pretreated energy storage means sent to the next step contains the cathode and anode materials during pyrolysis. Pyrolysis 18 is carried out in a carbon dioxide atmosphere containing a protective gas that inhibits oxidation reactions and is selected from argon and nitrogen, and involves at least partial carbonation of the contained lithium. Materials contained in the product stream, such as in particular active material and binder components, are further decomposed, and carbon dioxide is obtained or liberated during pyrolysis 18.

[0076] The products obtained during pyrolysis 18 are then subjected to a mechanical treatment 20. This treatment step serves in particular to further concentrate the lithium-containing product stream 16 for further improving the processing of lithium. In particular, this treatment step serves, for example, to separate, by discharge 22, aluminum and copper foils and shell parts, if still present, from the active material or lithium-containing product stream 16.

[0077] The lithium is then separated by a separation step 24. This is carried out by leaching the product obtained in the above steps. In particular, a neutral leaching is carried out in aqueous solution by mixing the product to be treated with water, so that an aqueous solution containing lithium in the form of lithium fluoride and lithium carbonate formed as water-soluble products during thermal decomposition can be discharged (discharge 26).

[0078] To remove and obtain graphite anode material from the lithium-containing product stream 16, the stream is then subjected to a flotation process 28. Carbon dioxide is introduced into the flotation tank along with the lithium-containing product stream 16 or the liquid contained therein, whereby the graphite is separated and removed from the lithium-containing product stream 16 via discharge 30.

[0079] The lithium-containing product stream 16 is finally subjected to hydrometallurgical reprocessing 32 to further carbonate the contained lithium and separate it in a further separation step by discharge 34. In addition to lithium, further components, particularly metals, can be discharged by pH conversion and / or extraction methods.

[0080] As shown in the first embodiment and in Figure 1, the carbon dioxide liberated during pyrolysis 18 can be recycled 36 in a cycle as needed and fed to at least one of the process steps of pyrolysis 18, separation 24, and flotation treatment 28. The returned or fed carbon dioxide may be purified before being returned or fed. [Explanation of symbols]

[0081] 10 Introduction 12 Pretreatment 14 Emission 16 Lithium-containing product stream 18 Pyrolysis 20 Mechanical Processing 22 Emission 24 separation 26 Emission 28 Flotation treatment 30 discharge 32 Hydrometallurgical reprocessing 34 Emission 36 Recirculation 38 Supply

Claims

1. 1. A method for reprocessing a lithium-containing energy storage means, comprising the steps of: The method comprises the following method steps: i) optionally pre-treating said lithium-containing energy storage means, said pre-treatment comprising at least one of thermal, mechanical and electrical pre-treatment; ii) pyrolyzing the optionally pretreated lithium-containing energy storage means to liberate carbon dioxide and carbonate at least a portion of the contained lithium in a carbon dioxide atmosphere; iii) separating the lithium in a separation step; iv) hydrometallurgically reprocessing the mixture obtained in process step iii) to further carbonate the contained lithium and separate the lithium in a further separation step; and v) returning the carbon dioxide liberated in process step ii) to at least one of process steps ii) and iii), The method includes at least

2. 1. A method for reprocessing a lithium-containing energy storage means, comprising the steps of: The method comprises the following method steps: i) optionally pre-treating said lithium-containing energy storage means, said pre-treatment comprising at least one of thermal, mechanical and electrical pre-treatment; ii) pyrolyzing the optionally pretreated lithium-containing energy storage means to liberate carbon dioxide and carbonate at least a portion of the contained lithium in a carbon dioxide atmosphere; iii) separating the lithium in a separation step; and iv) hydrometallurgically reprocessing the mixture obtained in process step iii) to further carbonate the lithium contained therein and separate the lithium in a further separation step; The method includes at least

3. 2. The method according to claim 1, characterized in that process step v) is carried out in such a way that at least a portion of the returned carbon dioxide is used in process step iii).

4. 4. The method according to claim 1, further comprising a further process step of flotation, preferably after process step iii) and before process step iv), wherein process step v) is carried out, if necessary, in such a way that at least a part of the returned carbon dioxide is used in the flotation.

5. 5. The method according to claim 1, wherein the carbon dioxide returned in process step v) is purified before being returned.

6. 6. The method according to any one of claims 1 to 5, characterized in that the lithium-containing energy storage means in method step ii) comprises a cathode material and an anode material.

7. Said lithium-containing energy storage means is pretreated according to method step i), which comprises the following reaction steps: i.1 Mechanically disassembling the lithium-containing energy storage means to a module or cell level; i.2 discharging said lithium-containing energy storage means; and i.3 Thermal treatment of the energy storage means decomposed to the module and / or cell level to decompose the conductive salt and volatilize the solvent, which is preferably condensed for recovery; 7. The method according to claim 1, further comprising at least one of the following steps:

8. 8. The process according to claim 1, wherein process step ii) is carried out in a continuously operated moving bed reactor.

9. 9. The method according to any one of claims 1 to 8, characterized in that a material selected from shredded material, production scrap, cells, modules and mixtures thereof is used as the lithium-containing energy storage means.

10. 10. The method according to any one of claims 1 to 9, characterized in that the method comprises flotation to obtain the anode material, the flotation preferably being carried out after method step iii) and before method step iv).

11. A method according to any one of claims 1 to 10, characterized in that the method is a method for recovering lithium and anode material from lithium-containing energy storage means.

12. The method according to any one of claims 1 to 11, characterized in that the anode material comprises graphite.

13. 13. The method according to any one of claims 1 to 12, characterized in that the method is a method for recovering lithium fluoride, which is separated in method step iii).

14. A method according to any one of claims 1 to 13, characterized in that the carbon dioxide atmosphere contains a protective gas which inhibits oxidation reactions and is preferably selected from argon and nitrogen.

15. The method comprises a thermal pretreatment of the energy storage means disassembled to the module and / or cell level in order to decompose the conductive salt and volatilize the solvent; and In method step ii), the shredded material is used as the lithium-containing energy storage means, the shredded material comprising a cathode material and an anode material; and 15. Method according to any one of claims 1 to 14, characterized in that the pretreated lithium-containing energy storage means is destroyed between the thermal pretreatment and method step ii).

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