Method for reconditioning lithium-containing energy accumulators

Abstract

The present invention relates to a method for reconditioning lithium-containing energy accumulators, the method comprising at least the following method steps: i) possibly pretreating the lithium-containing energy accumulator, with the pretreatment comprising at least one of the following: thermal, mechanical and electrical pretreatment; ii) pyrolyzing the possibly pretreated lithium-containing energy accumulator, with the release of carbon dioxide, and with at least partial carbonation, under a carbon-dioxide atmosphere, of the lithium contained; iii) separating lithium in a separating step; and iv) hydrometallurgically reconditioning the mixture obtained in method step iii), with further carbonation of the lithium contained and with separation of lithium in a further separating step, with v) carbon dioxide released in method step ii) being returned in at least one of method steps ii) and iii).

Description

[0001] Processes for reprocessing lithium-containing energy storage devices >

[0002] Description

[0003] The present invention relates to a method for reprocessing lithium-containing energy storage devices. In particular, the present invention relates to a method by which lithium-containing energy storage devices, in particular lithium-ion batteries, can be reprocessed or recycled.

[0004] Sustainable and resource-efficient work is becoming increasingly important in all areas of technology. Due to the increasing use of electromobility, the recycling of lithium-ion batteries is gaining increasing attention and relevance. The recycling rate of batteries influences the life cycle assessment of electric vehicles. Furthermore, the EU Battery Directive requires a recycling efficiency of 50% by weight. This legislative framework will become more stringent in the future with regard to recycling efficiency. In addition, basic recovery quotas will be introduced. Until now, economic interests have led to the recovery of cobalt and nickel being the focus of established recycling processes. For example, cobalt, nickel, and manganese account for up to 80% of the material values ​​in the recycling of NMC cells (lithium nickel manganese cobalt oxide).However, for cost reasons, cobalt is expected to be largely omitted from future battery systems (lithium iron phosphate, LFP system) or at least minimized (nickel cobalt aluminum, NCA system). Lithium, on the other hand, will likely remain an established component of lithium-ion batteries due to its properties, such as low density and lowest standard potential. This gives rise to the need for efficient lithium recycling. Furthermore, economic and geopolitical factors are driving lithium recycling.

[0005] WO 2021 / 226719 A1 describes a green chemistry hydrometallurgical process for recovering one or more metals from a metal-containing material, comprising leaching the metal-containing material with formic acid, obtaining 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 lithium-ion batteries, resulting in Li formate remaining in solution and precipitating salts containing one or more of the formates Ni, Co, and Mn.The steps may include filtration of the leachate, sulfurization of the retained metal formate salts to produce metal sulfate salts, purification of the filtered leachate by addition of lithium carbonate and filtration, dewatering of the purified leachate, and thermal decomposition of the resulting lithium salts to produce battery-grade lithium carbonate.

[0006] CN109921125 A describes pretreatment methods for recycling lithium batteries, comprising the following steps: Step 1, disassembling a lithium battery to obtain a positive plate, a negative plate, a separator, a battery case, and a cover plate; Step 2, performing pre-grinding on the positive plate and selecting a positive electrode material and a conductive agent; Step 3, performing heat treatment on the positive electrode material; Step 4, mixing the heat-treated positive electrode material with an active additive for mechanical grounding to activate the positive electrode material; and Step 5, performing pre-grinding on the negative plate and then placing it in a shaker for separation to select a metal foil material and a treatment.

[0007] CN106505271 A discloses a method for recycling a lithium-ion battery. The method comprises the steps of cutting electrode plates removed from the lithium-ion battery and gradually heating and heat-preserving them in a heating furnace with a gas collection device; placing the electrode plates subjected to heating and heat-preserving in a sodium hydroxide solution until an electrode material is peeled off from the aluminum foil; directly recycling the aluminum foil, simultaneously collecting the electrode material, washing and drying the electrode material, and then uniformly grinding the electrode material in a ball mill; and testing the contents of various elements in the electrode material.

[0008] CN113921931 A relates to a method for recycling lithium carbonate from spent lithium-ion batteries, particularly to a method for recycling lithium carbonate from spent lithium-ion batteries by thermal reduction using carbon. This document aims to solve the technical problems of the difficulty of separating the positive and negative electrode materials in the existing black powder from spent lithium-ion batteries and the difficulty of recycling lithium resources.According to the method, a decommissioned lithium-ion battery can be directly crushed and sieved to obtain the black powder under conditions of no discharge and no disassembly and separation. Lithium is largely recycled from the decommissioned lithium-ion battery, while nickel, cobalt, and manganese in the filter residue obtained by the initial suction filtration step are used to produce a precursor or are selectively recycled. However, the solutions known from the state of the art may still have potential for improvement, particularly with regard to the efficient recycling of lithium-containing batteries.

[0009] It is therefore the object of the present invention to provide a measure by which at least one disadvantage of the prior art is at least partially overcome. In particular, it is an object of the present invention to provide a solution by means of which the recycling of lithium-containing batteries can be improved.

[0010] The object is achieved according to the invention by a method having the features of claim 1 and claim 2. The object is further achieved by using the method according to the invention for lithium and anode material recovery from lithium-containing energy storage devices. Preferred embodiments of the invention are disclosed in the subclaims, in the description, and in the figures. Further features described or shown in the subclaims or in the description or figures may constitute an object of the invention, individually or in any combination, unless the context clearly indicates otherwise.

[0011] The present invention relates to a method for reprocessing lithium-containing energy storage devices, wherein the method comprises at least the following method steps: i) optionally pretreating the lithium-containing energy storage device, wherein the pretreatment comprises at least one of thermal, mechanical, and electrical pretreatment; ii) pyrolyzing the optionally pretreated lithium-containing energy storage device with the release of carbon dioxide and under a carbon dioxide atmosphere with at least partial carbonation of the lithium contained; iii) separating lithium in a separation step;and iv) hydrometallurgical processing of the mixture resulting from process step iii) with further carbonation of the lithium contained and with separation of lithium in a further separation step, wherein v) carbon dioxide released in process step ii) is recycled to at least one of process steps ii) and iii);

[0012] The present invention also relates to a method for reprocessing lithium-containing energy storage devices, wherein the method comprises at least the following method steps: i) optionally pretreating the lithium-containing energy storage device, wherein the pretreatment comprises at least one of thermal, mechanical and electrical pretreatment; ii) pyrolyzing the optionally pretreated lithium-containing energy storage device with release of carbon dioxide and under a carbon dioxide atmosphere with at least partial carbonation of the lithium contained; iii) separating lithium in a separation step; and iv) hydrometallurgical processing of the mixture resulting in method step iii) with further carbonation of the lithium contained and with separation of lithium in a further separation step.

[0013] The method described above is thus used to reprocess energy storage devices containing lithium. Reprocessing is understood, in particular, as a process that allows the recovery of raw materials contained in the energy storage device. For example, an energy storage device usually contains metals or metal compounds that can be used as raw materials for value creation. In particular, the lithium used in energy storage devices can be recovered using the method described here. However, the method is not limited to the extraction of lithium, as will be understood by those skilled in the art. For example, anode material such as graphite can also be recovered.

[0014] Accordingly, the choice of reprocessed lithium-containing energy storage devices is not limited, but lithium or lithium-ion batteries can be used. Given the expanding electromobility sector, the recycling of used lithium-ion batteries is increasingly becoming a priority. Accordingly, the process described here primarily uses lithium-containing energy storage devices that have reached the end of their useful life. Such energy storage devices are also called "end-of-life" energy storage devices. However, other energy storage devices can also be used, such as defective or damaged energy storage devices. The advantage of using secondary material as the starting material for the process described here is that lithium is more highly concentrated in energy storage devices than in primary ores, for example.This fundamentally simplifies extraction compared to mining and is therefore advantageous. At the same time, lithium is currently not sufficiently recycled, which is why the invention contributes to the recycling of battery raw materials. According to the invention, shredded material, production scrap, cells, modules, and mixtures thereof can be used as lithium-containing energy storage materials.

[0015] The method described here comprises at least the following method steps.

[0016] According to process step i), the lithium-containing energy storage device is optionally pretreated, wherein the pretreatment, if carried out, comprises at least one of thermal, mechanical, and electrical pretreatment. The pretreatment serves, in particular, to prepare the lithium-containing energy storage device used for the further process and, in the process, for the actual recovery of the raw materials, in particular for the recovery of the lithium, and, if appropriate, to begin with the separation of some raw materials from the lithium-containing product stream. This product stream is also referred to as black mass and usually contains at least the active material, preferably cathode active material and anode active material, with a corresponding lithium compound.

[0017] Accordingly, pretreatment can ensure that subsequent process steps are more efficient or can be carried out with greater safety. Pretreatment, for example, makes it possible to remove plastic components or other specific materials, such as metals, solvents, and WEEE (Waste of Electrical and Electronic Equipment). For example, cabling, control units, such as the battery management system (BMS), or components referred to as heavy fraction, such as the module housing or parts thereof, for example, made of iron or aluminum, or even contacts, such as those made of copper, can be separated from the lithium-containing product stream that is to be further treated.

[0018] Thermal, mechanical, and electrical pretreatment are particularly advantageous as pretreatments. Only thermal, only mechanical, only electrical, or a combination of several of the respective pretreatments can be performed simultaneously or sequentially.

[0019] During thermal treatment, in particular, thermal deactivation of the energy storage device can occur so that the subsequent steps can be carried out without safety concerns. Preferably, the conducting salt, in particular LiPF6, is decomposed during the thermal pretreatment. The decomposition products of the conducting salt are then available for further conversion in the subsequent pyrolysis. Furthermore, during thermal pretreatment, the organic components or a portion of low-boiling components, preferably solvents, can be volatilized and then condensed. Preferably, during thermal pretreatment, solvents of the electrolyte are volatilized and condensed for recovery. Thus, thermal pretreatment can serve both a safety aspect and an already incipient separation of the materials in the energy storage device.

[0020] Mechanical pretreatment can, in particular, involve disassembling an energy storage device. For example, the energy storage device used can be disassembled down to the module or cell level to simplify subsequent process steps and, if necessary, to remove components such as contacts, housing components, and control units from the lithium-containing product stream. Furthermore, it is possible to mechanically reduce the energy storage device, such as shredding it, for example, under protective gas, while separating the electrolyte.

[0021] Electrical pretreatment can, in particular, include a preferably complete discharge of the energy storage device. This can be achieved purely electrically, by conducting a conventional discharge, or by thermal or mechanical treatment. Electrical discharge offers the advantage that the lithium ions are incorporated into the transition metal oxides on the cathode side. Since the cathode material is decomposed into short-chain components during pyrolysis, the lithium in the cathode material is more accessible after pyrolysis than it would be in the anode material. This can improve the lithium yield.

[0022] Following the above, it may be particularly preferred if, according to process step i), a pretreatment of the lithium-containing energy storage device is carried out, wherein process step i) comprises at least one of the following process steps:

[0023] 1.1 Mechanical disassembly of the lithium-containing energy storage device, preferably down to the module or cell level; and

[0024] 1.2 Discharging the lithium-containing energy storage device; and

[0025] 1.3 Thermal treatment of the energy storage device, preferably wherein the energy storage device is dismantled down to the module level and / or cell level, preferably for decomposing the conductive salt and for evaporating solvent, wherein the solvent is preferably condensed for recovery.

[0026] In a preferred embodiment, the method comprises a thermal pretreatment of the energy storage device dismantled down to the module level and / or cell level for decomposing the conductive salt and for evaporating solvent, wherein in method step ii) shredded material is used as the lithium-containing energy storage device, wherein the shredded material comprises cathode material and anode material, wherein between the thermal pretreatment and method step ii) a comminution of the pretreated lithium-containing energy storage device takes place.

[0027] Preferably, the temperature during the thermal pretreatment does not exceed 350 °C.

[0028] According to process step ii), the process further comprises pyrolyzing the optionally pretreated lithium-containing energy storage device with the release of carbon dioxide and under a carbon dioxide atmosphere with at least partial carbonation of the lithium contained. Accordingly, this step can comprise thermal treatment of the optionally pretreated energy storage device, i.e., the lithium-containing product stream resulting from the pretreatment. Alternatively, within the meaning of the present invention, it is not excluded that the energy storage devices to be treated are subjected directly to the thermal treatment or pyrolysis according to process step ii) without pretreatment. Accordingly, the product stream from the pretreatment can be used for process step ii), such as shredded material, production scrap, whole cells, modules, but also the untreated energy storage device.It is important that the lithium-containing active material or electrode material, advantageously cathode material, of the energy storage device is used in order to be able to recover the lithium. In process step ii), the lithium-containing energy storage device preferably comprises cathode material and anode material. Accordingly, it is preferable not to use a material that contains only minor residues of anode material. For example, in process step ii), the lithium-containing energy storage device preferably contains > 20 wt.% anode material, particularly preferably > 20 wt.% graphite. In process step ii), the lithium-containing energy storage device preferably further comprises the conductive salt and / or its decomposition products. In process step ii), the lithium-containing energy storage device preferably further comprises the current conductors.In other words, preferably, no separation of cathode material, anode material, conducting salt, and current conductors, as well as their decomposition products, takes place prior to pyrolysis. Preferably, shredded material is used for pyrolysis to which the active material powder from the cathode and anode adheres (so-called "powder-coated shredded material").

[0029] In a preferred embodiment, the temperature during process step ii) (pyrolysis) is 500 °C to 700 °C.

[0030] This process step serves in particular to at least partially carbonate the lithium contained in the lithium-containing product stream, i.e., in particular, to convert the lithium compounds present in the optionally pretreated battery cells into water-soluble lithium carbonate. This enables subsequent selective leaching of the carbonated lithium in aqueous solution without dissolving further components from the active mass. A further advantage is the possible combination of leaching with a flotation process to recover the graphite, as described in more detail below. During pyrolysis, lithium fluoride is also preferably formed, which can subsequently be separated. The process therefore preferably also represents a process for recovering lithium fluoride from lithium-containing energy storage devices.

[0031] To carry out process step ii), a reducing atmosphere is important to ensure that carbonation can proceed undisturbed. The reducing atmosphere can be achieved simply by producing and releasing CO2 during the pyrolysis of the lithium-containing material. In principle, the active material comprises materials such as NMC and the binder, which also release carbon dioxide during pyrolysis under a reducing atmosphere. Accordingly, it can be advantageous if the active material containing lithium and having one or more oxygen atoms in its molecular structure and the binder are present in this step as a carbonaceous or organic material, such as PVDF. In addition to the resulting carbon dioxide, a protective gas such as argon or nitrogen can be supplied to this process step.This allows for a suitable atmosphere to be created, although this need not be formed solely by carbon dioxide. However, according to the invention, the resulting carbon dioxide is also recycled, as described in detail later.

[0032] In the process according to the invention, it is preferred that the carbon dioxide atmosphere, optionally also in combination with a protective gas such as argon or nitrogen, suppresses undesirable oxidation reactions. Preferably, the atmosphere also enables the separation of lithium fluoride in step iii). Without wishing to be bound by this theory, the inventors assume that the carbon dioxide atmosphere forms a protective gas atmosphere. Pyrolysis under the carbon dioxide atmosphere leads to the decomposition of binder and the decomposition of the long-chain transition metal oxides into simple transition metal oxides, thereby releasing lithium. This pyrolytic change in the feedstock is evident, for example, in the flaking of powder coatings from the conductive foils (aluminum and copper foils).During thermal decomposition of the long-chain transition metal oxides under non-oxidizing conditions, the lithium is released from the matrix. Since entire modules / cells are treated, which still contain residues of the electrolyte and conducting salt, the yield is particularly high.

[0033] In a preferred embodiment of the process according to the invention, in process step ii) pyrolysis and in the optional thermal pretreatment, transition metals such as cobalt, nickel and manganese are not reduced to metallic transition metal.

[0034] After pyrolysis, the product stream, i.e. the lithium-containing material that has undergone pyrolysis, is fed to process step iii). According to process step iii), lithium is separated in a first separation step, whereby separation is understood to mean, in particular, the selective separation of a lithium compound from the residual mass. This can be achieved, in particular, by leaching the product obtained in the previously described steps. In particular, neutral leaching can take place in an aqueous solution by adding water to the product to be treated. This allows the lithium, in the form of lithium carbonate, which was produced by thermal carbonation as described above, to be washed out highly selectively without entrainment of foreign substances. This allows lithium carbonate to be separated in a comparatively clean form and subsequently processed to produce lithium.In a preferred embodiment, fluoride, in particular lithium fluoride, is also separated in process step iii). Specifically, neutral leaching, for example, takes place using only water, which is an advantage over prior art processes, which often required the use of acids. The introduction of carbon dioxide into the solution is advantageous here, as this produces carbonic acid, which can improve the dissolution of lithium compounds in aqueous solution and thus the removal of lithium. In a preferred embodiment, the carbon dioxide serves to adjust a pH in the neutral to slightly acidic range, thereby facilitating the selective separation of lithium.

[0035] According to process step iv), the mixture produced in process step iii), which has been depleted of lithium, is further processed hydrometallurgically. In this process step, the remaining lithium or lithium compound is further carbonated. This step involves the separation of other substances, particularly metals such as aluminum, iron, cobalt, nickel, and manganese, and thus also of residual lithium. The removal of the respective metals can be achieved, as is generally known for hydrometallurgical processes, by pH changes and / or by extraction with organic solvents.

[0036] In the process described here, it is further provided according to process step v) that carbon dioxide released in process step ii) is recycled to at least one of process steps ii) and iii).

[0037] For example, the carbon dioxide released in process step ii) can only be returned to process step ii), the carbon dioxide released in process step ii) can only be returned to process step iii), or the carbon dioxide released in process step ii) can be fed to both process steps ii) and iii) and, if necessary, to further process steps.

[0038] When the resulting carbon dioxide is fed into process step ii), it serves to create a reducing atmosphere and to provide a reagent for carbonation.

[0039] When carbon dioxide is added to process step iii), this also enables the addition of a reagent for carbonation as well as improved dissolution of the lithium compounds in aqueous solution by formation of carbonic acid.

[0040] Essentially, the use of exhaust gases from the thermal treatment of lithium-based energy storage systems is used to carbonate Li compounds, thus becoming a central point in the recovery of lithium as a new raw material. This creates a carbon dioxide cycle that is specifically tailored to the process developed here and offers significant synergistic advantages. For example, in addition to the recycling of carbon dioxide, other components, particularly gaseous ones, such as protective gases such as argon or nitrogen, can also be recycled. These gases, which occur in step ii) or are fed in there, can be recycled. These can simply be recycled together with the carbon dioxide or purified and used in a targeted manner. This also enables resource conservation and thus improved sustainability.

[0041] As described above, carbon dioxide is used in process step ii) to carbonate lithium. For this purpose, it is advantageous to add carbon dioxide to process step ii). By recycling the resulting carbon dioxide, the addition of fresh carbon dioxide can be avoided or at least significantly reduced. Furthermore, the production of carbon dioxide as exhaust gas, which is usually released into the environment in state-of-the-art processes, can be prevented. The process described here can therefore offer significant advantages in ecological aspects. Furthermore, the process can be carried out with reduced resources and at a lower cost. This results in particular in advantages over state-of-the-art solutions.For example, conventional processes for the thermal recycling of Li-ion batteries generate CO2 and emit the climate-damaging greenhouse gas into the environment, which runs counter to the aim of reducing CO2 emissions from industrial processes.

[0042] In particular, with an additional thermal pretreatment according to process step i), the carbon dioxide is thus generated in the second thermal treatment step through the appropriate temperature control of the thermal pretreatment according to process step i) and the pyrolysis according to process step ii). This enables the targeted generation and use of the resulting carbon dioxide.

[0043] According to the invention, emissions are reduced by recycling the CO2 and high lithium yields are achieved without additional additives, such as carbonation agents, which are necessary in the conventional process. This also eliminates the need for additional additives, such as pH adjusters, for further hydrometallurgical treatment. In the conventional hydrometallurgical process, an increased amount of leaching agents, such as HCl and H2SO4, pH adjusters, such as NaOH or KOH, or oxidizing agents, such as H2O2, is required because the water- and CO2-based process requires a preliminary separation of lithium and graphite. This achieves a mass reduction for the hydrometallurgy, which can be avoided with the invention.

[0044] Through targeted recycling of CO2, it is harnessed and converted into a product. This provides the benefits of thermal pretreatment without undesirable side effects. The use of CO2 generated in the process as a usable resource for both lithium and graphite through an innovative recycling process makes this possible in a very advantageous way.

[0045] It may further be preferred for the process to comprise the further process step of flotation, for example before process step iv). In a preferred embodiment, the process comprises flotation to obtain the anode material. The flotation preferably takes place after process step iii) and before process step iv). In one embodiment, process step v) takes place in such a way that recycled carbon dioxide is at least partially used in the flotation. Flotation is understood, in a manner known per se, to be a physico-chemical separation process for fine-grained solids based on the different surface wettability of the particles. The process takes place in a liquid, such as water in particular, and further with the addition of a gas, such as air. In the embodiment described here, anode material, in particular graphite, can be removed from the product stream in a particularly preferred manner.Graphite is typically used as an anode material in energy storage systems and is also a valuable raw material classified as critical by the EU. In the process according to the invention, the anode material preferably comprises graphite.

[0046] If necessary, very small amounts of additives are added to the aqueous solution to influence the attrition, causing graphite particles to float to the surface as foam and metallic particles to sink. The foam can then be skimmed off, thus separating the graphite.

[0047] Separating the graphite offers a further significant advantage over prior art processes, which generate CO2 by burning graphite and converting it to CO2 / CO. According to the invention, however, the loss of a critical raw material with additional CO2 generation can be prevented. In preferred embodiments of the process according to the invention, the graphite is inert.

[0048] The flotation process according to this embodiment can particularly preferably be carried out using carbon dioxide, since carbon dioxide is generated in-situ in the process, does not interfere with the process, and is also advantageously suitable for bubble formation or foam formation.

[0049] It may further be preferred that the carbon dioxide recycled in process step v) is purified before being recycled, in particular into at least one process step of process steps ii) and / or iii) and / or into the flotation. In particular, foreign substances present in the gas stream can thus be removed. This can be achieved, for example, by a filter unit, through which it is possible to remove entrained solids from the gas stream. Additionally or alternatively, it is also possible to remove gaseous impurities from the gas stream by using gas separation processes known per se. This step enables process step ii) to be carried out particularly efficiently, since no foreign substances or waste materials or, in principle, impurities are reintroduced into the product stream to be treated.The product leaving process step ii) can therefore be improved with regard to the presence of undesirable impurities, which enables improved purification of the resulting lithium.

[0050] It may further be preferred that carbon dioxide be supplied as fresh gas to process step ii) at least temporarily. This configuration can take into account the fact that the recycled carbon dioxide may not be sufficient to form the atmosphere in process step ii). Accordingly, new or non-recycled carbon dioxide can also be supplied to process step ii). Adding fresh gas can be advantageous, particularly during process start-up.

[0051] In principle, the origin of the CO2 fresh gas is not restricted. However, it is advantageous, for example, for the CO2 to originate from a so-called carbon capture process, which can also be referred to as carbon dioxide capture (CC), which describes the capture of carbon dioxide, particularly from combustion exhaust gases, and its subsequent use in further chemical processes. This design can further improve the ecological aspects and thus the sustainability of the process described here.

[0052] It may further be preferred that process step ii) be carried out in a continuously operated moving-bed reactor. It has been shown that, particularly in this configuration, the circulation of the material allows for effective carbonation of the lithium species. This allows for effective leaching of the lithium carbonate in subsequent steps, thus enabling particularly effective and clean recovery of the lithium.

[0053] In principle, however, the process is not limited to a continuously operated moving-bed reactor. Batch processes or other reactors are also possible within the meaning of the present invention to carry out the pyrolysis according to process step ii).

[0054] It may further be preferred that process step ii) is carried out at temperatures in a range from greater than or equal to 300°C to less than or equal to 800°C. Preferably, process step ii) can be carried out at temperatures in a range from greater than or equal to 350°C to less than or equal to 560°C, for example from greater than or equal to 400°C to less than or equal to 560°C. Particularly in this temperature range, the process step can be carried out in an energy-efficient manner. Furthermore, however, it can be ensured that effective thermal carbonation takes place, thus ensuring that a large amount of lithium compounds is already carbonated and reacts to form lithium carbonate.

[0055] Particularly in this embodiment, but not limited to it, it is possible for the exhaust gas stream, i.e., in particular the discharged and recirculated carbon dioxide stream, to have a high temperature, which is also usable in the process described here. In principle, the waste heat from the carbon dioxide stream leaving the pyrolysis process can be used to control the temperature of other processes, such as leaching lithium carbonate or hydrometallurgical processes. For this purpose, the hot carbon dioxide can pass through a heat exchanger or be introduced directly into a process.

[0056] Purely as an example, the exhaust gas can be recycled into the thermal pretreatment to create a suitable process atmosphere for the targeted phase transformations within the cathode material, which is particularly advantageous for subsequent treatments.

[0057] It may further be preferred that mechanical processing of the product obtained in process step ii) is carried out between process steps ii) and iii). This processing step can serve, in particular, to further concentrate the lithium-containing material in order to further improve the processing of the lithium. In detail, this processing step serves, for example, to separate aluminum and copper foils as well as housing parts from the active material, insofar as they are still present. This can be done, for example, using heavy-duty sieves or impact mills. This process step can be carried out in a manner understandable to the person skilled in the art depending on the substances actually still present or their amount.

[0058] Preferably, no solid carbon is added to the thermal pretreatment and / or pyrolysis process. In particular, coal, activated carbon, anthracite, or the like are preferably not added to the thermal pretreatment and / or pyrolysis.

[0059] Following the above, the present invention further relates to the use of a method as described above for reprocessing a lithium-containing energy storage device. In particular, the present invention relates to the use of a method as described above for recovering lithium and / or anode material from lithium-containing energy storage devices. In other words, the method according to the invention preferably represents a method for recovering lithium and / or anode material from lithium-containing energy storage devices.

[0060] As described above, the defined use of CO2 generated through targeted recycling allows it to be harnessed and converted into a product. This provides the advantages of thermal pretreatment without undesirable side effects. The use of CO2 generated in the process as a usable resource for both lithium and graphite through an innovative recycling process enables this in a very advantageous way. Compared to state-of-the-art solutions, good ecological behavior is combined with comparatively low costs and a potentially high purity of the recovered lithium. The process is thus cost-effective and ecologically improved, enabling economical lithium and graphite recovery.

[0061] The invention is explained below by way of example with reference to the attached drawing, wherein the features shown below can represent an aspect of the invention both individually and in combination, and wherein the invention is not limited to the following drawing, the following description and the following embodiments.

[0062] It shows:

[0063] Fig. 1 is a schematic flow diagram of an exemplary embodiment of a method according to the present invention.

[0064] Figure 1 shows a schematic flow diagram of a process according to the present invention. Such a process is used for reprocessing lithium-containing energy storage devices and, in doing so, for recovering the raw materials incorporated therein, in particular for recovering lithium.

[0065] Shown is the introduction of 10 lithium-containing energy storage devices into the process.

[0066] First, an optional pretreatment 12 of the lithium-containing energy storage device is carried out. This pretreatment 12 can be thermal, mechanical, and / or electrical, for example, and serves in particular to discharge or deactivate the energy storage device. Furthermore, a discharge 14 of components of the energy storage device can be carried out. The discharge 14 makes it possible, for example, to remove plastic components, metal components, or even electrical components, without being limited thereto, and thus to separate them from the lithium-containing product stream 16 to be further treated. Accordingly, the pretreatment 12 preferably comprises at least one of the following process steps:

[0067] 1.1 mechanical disassembly of the lithium-containing energy storage device;

[0068] 1.2 Discharging the lithium-containing energy storage device; and

[0069] 1.3 Thermal treatment of the energy storage device.

[0070] Furthermore, a preferably continuous pyrolysis 18 of the continued product stream 16 or of the optionally pretreated energy storage device takes place, for example at temperatures in the range of 300°C to 800°C and / or in a moving-bed reactor. The pyrolysis 18 takes place under a carbon dioxide atmosphere and thus under reducing conditions, and with at least partial carbonation of the lithium contained. Furthermore, materials contained in the product stream, such as in particular active material and binder components, decompose, so that carbon dioxide is produced or released during the pyrolysis 18.

[0071] Subsequently, the product resulting from pyrolysis 18 is optionally subjected to mechanical treatment 20. This treatment step can serve, in particular, to further concentrate the lithium-containing product stream 16 in order to further improve the processing of the lithium. Specifically, this treatment step serves, for example, to separate aluminum and copper foils as well as housing parts from the active mass or from the lithium-containing product stream 16, to the extent that they are still present, by means of a discharge 22.

[0072] Subsequently, lithium is separated in a separation step by means of a separation device 24. This can be achieved, in particular, by leaching the product obtained in the previously described steps. In particular, neutral leaching can take place in an aqueous solution by adding water to the product to be treated. This allows an aqueous solution containing lithium in the form of lithium carbonate, which has formed as a water-soluble product during pyrolysis, to be discharged through an outlet 26.

[0073] To remove graphite from the lithium-containing product stream 16, it is subsequently subjected to a flotation process 28. A gas, such as carbon dioxide in particular, can be introduced into a flotation vessel or the liquid contained therein with the lithium-containing product stream 16, whereby the graphite separates and can be removed from the lithium-containing product stream 16 via a discharge 30.

[0074] Finally, a hydrometallurgical processing 32 of the lithium-containing product stream 16 is carried out, in particular with further carbonation of the lithium contained and with separation of lithium in a further separation step by the discharge 34. In addition to lithium, other components, in particular metals, can be discharged by pH change processes and / or by extraction processes.

[0075] Figure 1 further shows that carbon dioxide released during pyrolysis 18 is circulated in a circuit 36 ​​and fed into at least one of the process steps of pyrolysis 18 and separation 24. Furthermore, the carbon dioxide can be fed to the flotation process 28. In principle, it may be preferable for the recirculated, i.e., supplied, carbon dioxide to be purified before being recirculated, i.e., supplied.

[0076] The recirculation system 36 may already be sufficient to create a suitable atmosphere for the pyrolysis 18. However, it may be necessary to supply carbon dioxide as fresh gas to the pyrolysis 18 through a feed 38, at least temporarily. Additionally or alternatively, protective gas can be supplied to the pyrolysis 18, which can also be recirculated and optionally purified.

[0077] In a further example, a method is described which also represents a method for lithium and anode material recovery from lithium-containing energy storage devices, wherein the anode material comprises graphite.

[0078] Production scrap, cells, modules and optionally also shredded material can be used as lithium-containing energy storage devices, whereby production scrap and modules in this example are dismantled down to the cell level.

[0079] First, the lithium-containing energy storage device undergoes pretreatment 12. This pretreatment 12 comprises thermal pretreatment of the energy storage device, dismantled down to the cell level, at no more than 350 °C to decompose the conductive salt and evaporate the solvent, with the solvent being condensed for recovery. The pretreated energy storage device is then shredded to provide shredded material for use as the lithium-containing energy storage device in the subsequent pyrolysis.

[0080] Furthermore, components of the energy storage device are removed (14). This removal (14) makes it possible, for example, to remove plastic components, metal components, or even electrical components and thus separate them from the lithium-containing product stream (16) that is to be further treated.

[0081] A continuous pyrolysis 18 of the continued product stream 16 or the pretreated energy storage device then takes place, approximately at temperatures in a range of 500°C to 800°C in a moving bed reactor. Prior to pyrolysis, no separation of anode and cathode material took place, so that the continued product stream 16 or the pretreated energy storage device contains cathode material and anode material during pyrolysis. The pyrolysis 18 takes place under a carbon dioxide atmosphere that suppresses oxidation reactions and contains a protective gas selected from argon and nitrogen, and with at least partial carbonation of the lithium contained. In addition, materials contained in the product stream, such as in particular active material and binder components, decompose, so that carbon dioxide is produced or released during pyrolysis 18.

[0082] Subsequently, a mechanical treatment 20 of the product resulting from pyrolysis 18 follows. This processing step serves, in particular, to further concentrate the lithium-containing product stream 16 in order to further improve the processing of the lithium. Specifically, this processing step serves, for example, to separate aluminum and copper foils as well as housing parts from the active mass or from the lithium-containing product stream 16, to the extent that they are still present, by means of a discharge 22.

[0083] Subsequently, lithium is separated in a separation step by means of a separation device 24. This occurs by leaching the product obtained in the previously described steps. In particular, a neutral leaching takes place in an aqueous solution by adding water to the product to be treated. This allows lithium to be discharged through an aqueous solution in the form of lithium fluoride and lithium carbonate (discharge device 26), which formed as water-soluble products during pyrolysis.

[0084] To remove and recover the anode material graphite from the lithium-containing product stream 16, the latter is subsequently subjected to a flotation process 28. Carbon dioxide is introduced into a flotation vessel or the liquid contained therein with the lithium-containing product stream 16, causing the graphite to separate and be removed from the lithium-containing product stream 16 via a discharge 30.

[0085] Finally, a hydrometallurgical processing 32 of the lithium-containing product stream 16 is carried out with further carbonation of the lithium contained and with separation of lithium in a further separation step by the discharge 34. In addition to lithium, other components, in particular metals, can be discharged by pH change processes and / or by extraction processes.

[0086] As shown in the first example and in Figure 1, carbon dioxide released during pyrolysis 18 can optionally be recirculated in a recirculation system 36 and fed into at least one of the process steps of pyrolysis 18, separation 24, and flotation process 28. The recirculated, i.e., supplied, carbon dioxide can be purified before being recirculated, i.e., supplied.

[0087] Reference symbol

[0088] 10 Insertion

[0089] 12 Pretreatment

[0090] 14 Discharge

[0091] 16 lithium-containing product stream

[0092] 18 Pyrolysis

[0093] 20 mechanical treatment

[0094] 22 Discharge

[0095] 24 Separation

[0096] 26 Discharge

[0097] 28 Flotation process

[0098] 30 Discharge

[0099] 32 hydrometallurgical processing

[0100] 34 Discharge

[0101] 36 Circulation

[0102] 38 Feed

Claims

Claims 1. A process for reprocessing lithium-containing energy storage devices, the process comprising at least the following process steps: i) optionally pretreating the lithium-containing energy storage device, the pretreatment comprising at least one of thermal, mechanical and electrical pretreatment; ii) pyrolyzing the optionally pretreated lithium-containing energy storage device with release of carbon dioxide and under a carbon dioxide atmosphere with at least partial carbonation of the lithium contained; iii) separating lithium in a separation step; and iv) hydrometallurgical processing of the mixture resulting from process step iii) with further carbonation of the lithium contained and with separation of lithium in a further separation step, wherein v) carbon dioxide released in process step ii) is recycled to at least one of process steps ii) and iii).

2. A process for reprocessing lithium-containing energy storage devices, the process comprising at least the following process steps: i) optionally pretreating the lithium-containing energy storage device, the pretreatment comprising at least one of thermal, mechanical and electrical pretreatment; ii) pyrolyzing the optionally pretreated lithium-containing energy storage device with release of carbon dioxide and under a carbon dioxide atmosphere with at least partial carbonation of the lithium contained; iii) separating lithium in a separation step; and iv) hydrometallurgical processing of the mixture resulting from process step iii) with further carbonation of the lithium contained and with separation of lithium in a further separation step.

3. A process according to claim 1, characterized in that process step v) is carried out in such a way that recycled carbon dioxide is at least partly used in process step iii).

4. Process according to one of claims 1 to 3, characterized in that the process preferably comprises the further process step of flotation after process step iii) and before process step iv), optionally wherein process step v) is carried out in such a way that recycled carbon dioxide is at least partly used in the flotation.

5. Process according to one of claims 1 and 3 to 4, characterized in that the carbon dioxide recycled in process step v) is purified before being recycled.

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

7. Method according to one of claims 1 to 6, characterized in that according to method step i) a pretreatment of the lithium-containing energy storage device takes place, wherein method step i) comprises at least one of the following method steps: 1.1 mechanical disassembly of the lithium-containing energy storage device down to the module or cell level; 1.2 Discharging the lithium-containing energy storage device; and 1.3 Thermal treatment of the energy storage device dismantled down to the module and / or cell level to decompose the conductive salt and evaporate the solvent, whereby the solvent is preferably condensed for recovery.

8. Process according to one of claims 1 to 7, characterized in that process step ii) is carried out in a continuously operated moving bed reactor.

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

10. Process according to one of claims 1 to 9, characterized in that the process comprises a flotation for obtaining the anode material, wherein the flotation preferably takes place after process step iii) and before process 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 devices.

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

13. A process according to any one of claims 1 to 12, characterized in that the process is a process for lithium fluoride recovery and in process step iii) lithium fluoride is separated.

14. Method according to one of claims 1 to 13, characterized in that the carbon dioxide atmosphere suppresses oxidation reactions and preferably contains a protective gas selected from argon and nitrogen.

15. The method according to any one of claims 1 to 14, characterized in that the method comprises a thermal pretreatment of the energy storage device dismantled down to the module level and / or cell level to decompose the conductive salt and to evaporate solvent, and that in method step ii) shredded material is used as the lithium-containing energy storage device, wherein the shredded material comprises cathode material and anode material, wherein between the thermal pretreatment and method step ii) a comminution of the pretreated lithium-containing energy storage device takes place.

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