Method for recycling lithium-ion batteries

Abstract

The present invention relates to a method for recycling lithium-containing electrochemical energy storage devices, in particular cells and / or batteries, i) an electrochemical energy storage device is first pulverized and an active material-containing fraction is separated from the pulverized material, wherein the active material-containing fraction comprises carbon (C), lithium (Li), and at least one element selected from the series comprising cobalt (Co), manganese (Mn), nickel (Ni), iron (Fe), and / or combinations thereof; ii) the fraction containing the active material is then fed to a smelting plant and melted in the presence of a slag former to form a molten slag phase and a molten metal phase; iii) A process in which lithium (Li) contained in the molten slag phase and / or the molten metal phase is converted into the gas phase by the addition of a fluorinating agent and carbon (C) is converted into the gas phase by the addition of an oxygen-containing gas and removed from the process as waste gas.

Description

[Technical Field]

[0001] The present invention relates to a method for recycling lithium-containing electrochemical energy storage devices, in particular cells and / or batteries. [Background technology]

[0002] The increasing electrification of the automotive sector is driving global demand for elemental lithium, a key component of lithium-ion batteries. To recover the valuable raw materials contained within lithium, such as lithium, cobalt, nickel, manganese, iron, aluminum, copper and vanadium, as efficiently as possible requires methods that minimize hydrometallurgical processing.

[0003] In a method known in the prior art, lithium-ion batteries are first discharged and crushed under inert gas. The coarse material is then separated from the electrolyte and dried in a thermal conditioning step. The resulting fractions are the electrolyte containing lithium in the form of lithium hexafluorophosphate, graphite, an active material consisting of valuable transition metals and lithium, metal foils with the active material attached, and various plastic and housing components.

[0004] The separated active materials are further treated and processed in hydro- and / or thermo-metallurgical processes. Some of the raw materials contained therein, such as graphite, cobalt, manganese, iron, aluminum, copper and vanadium, are extracted at various stages of the process. Lithium is usually only extracted in a further stage of the recycling process.

[0005] WO2020 / 104164A1 also discloses a process in which most of the lithium can be fumigated from the slag phase as lithium chloride by adding alkali metal chlorides and / or alkaline earth metal chlorides. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] WO 2020 / 104164 A1 Summary of the Invention [Problem to be solved by the invention]

[0007] It is therefore an object of the present invention to provide an improved method for recycling lithium-containing electrochemical energy storage devices, in particular cells and / or batteries, compared to the prior art, and in particular to provide a process for recycling lithium-containing electrochemical energy storage devices that can minimize hydrometallurgical processing. [Means for solving the problem]

[0008] Description of the Invention According to the invention, this problem is solved by a method having the features of claim 1.

[0009] In the method proposed by the present invention for recycling lithium-containing electrochemical energy storage devices, in particular cells and / or batteries, i) An electrochemical energy storage device is first pulverized, and an active material-containing fraction is separated from the pulverized material, where the active material-containing fraction contains carbon (C), lithium (Li), and at least one element selected from the series including cobalt (Co), manganese (Mn), nickel (Ni), iron (Fe), and / or combinations thereof. The active material-containing fraction is then fed to a smelting apparatus and melted in the presence of a slag-forming agent to form a molten slag phase and a molten metal phase (step ii). The lithium (Li) contained in the molten slag phase and / or the molten metal phase is then converted to a gas phase by the addition of a fluorinating agent, and the carbon (C) is converted to a gas phase by the addition of an oxygen-containing gas, which is then removed from the process as waste gas (step iii).

[0010] According to the method of the present invention, the fraction containing the active material is reacted in a refinery under high temperature and reducing conditions. By targeted administration of a fluorinating agent, lithium is directly fluorinated and quantitatively extracted as a lithium fluoride-containing gas at an early stage of the process. The recovery rate is advantageously at least 90%, more preferably at least 95%, and even more preferably 99%, based on the total amount of lithium fed to the recycling process. The lithium thus transferred to the gas phase can be directly recovered in a subsequent condensation step. At the same time, valuable metals, especially cobalt and nickel, are concentrated in the molten metal phase, while less valuable metals, especially iron and manganese, are oxidized and converted to slag. Thus, the method of the present invention minimizes the hydrometallurgical recovery of lithium and valuable metals. DETAILED DESCRIPTION OF THE INVENTION

[0011] Further advantageous embodiments of the invention are defined in the dependent claims. The features individually recited in the dependent claims can be combined with one another in a technically meaningful manner to define further embodiments of the invention. Furthermore, the features defined in the claims are further defined and explained in this specification, thereby indicating further preferred embodiments of the invention.

[0012] For the purposes of this invention, the term "melting unit" refers to a conventional bath melter or an electric arc furnace (EAF).

[0013] For the purposes of this invention, the term "fraction containing active material" refers to a mixture essentially containing the anode and cathode materials of a lithium-containing cell and / or battery. This fraction is obtained by mechanical processing from crushed electrochemical energy storage devices. The anode material is usually made of graphite and is capable of containing lithium ions. On the other hand, the cathode material is formed by lithium-containing transition metal oxides, which can have different cell chemistries depending on the material system.

[0014] For the purposes of the present invention, the term "oxygen-containing gas" is understood to mean air, oxygen-enriched air or pure oxygen, which gas is advantageously fed to the refinery via an injector.

[0015] For the purposes of the present invention, the term "injector" is understood to mean, unless otherwise defined, a lance or injection tube formed essentially from a hollow cylindrical element. In a preferred embodiment, at least one injector comprises a Laval nozzle through which an oxygen-containing gas is injected into the molten slag and / or metal phase. A Laval nozzle is characterized by consisting of a converging section and a diverging section adjacent to each other at the nozzle throat. The radius of the narrowest cross section, the exit radius, and the length of the nozzle may vary depending on the respective design case.

[0016] In a first embodiment, the fraction containing the active material comprises at least the elements carbon and lithium and at least one element selected from the series comprising cobalt, manganese, nickel, iron and / or combinations thereof. Additionally, at least one element from the series comprising phosphorus, sulfur, vanadium, aluminum and / or copper may be present.

[0017] The process according to the invention can be carried out under atmospheric pressure or under reduced pressure. When the process is carried out at atmospheric pressure (1 atmosphere), the fraction containing the active material is melted in the presence of a slag-forming agent at a temperature of preferably at least 1000°C, more preferably at least 1250°C, even more preferably at least 1450°C, and most preferably at least 1600°C. On the other hand, when carried out under reduced pressure, for example at a pressure of less than 1000 mbar, the fraction containing the active material is melted in the presence of a slag-forming agent at a temperature adapted to the respective reduced pressure, as appropriate.

[0018] The temperature of the gas phase and / or the exhaust gas is preferably detected continuously, if necessary.

[0019] For example, FeO, CaO, SiO2, MgO and / or Al2O3 can be used as slag formers. 4, Other mixed oxides such as may also be added.

[0020] The molten metal phase obtained in step ii) of the process according to the invention is preferably scraped off as soon as the desired concentration of valuable metals is reached, and can then be fed to subsequent hydrometallurgical processing steps, in particular separation and purification steps, while the molten slag phase, after scraping off, can be granulated and fed to further utilization, for example, road construction.

[0021] To obtain a sufficiently reducing atmosphere in the refinery and / or in the exhaust gas, carbon (C) is oxidized to carbon monoxide (CO) in step iii) together with an oxygen-containing gas. Advantageously, the proportion of carbon monoxide in the gas phase and / or in the exhaust gas can be continuously detected and adjusted by a corresponding enrichment or reduction of the oxygen partial pressure, if necessary. The oxygen-containing gas can preferably be supplied to the refinery via at least one injector.

[0022] The lithium converted as lithium fluoride-containing gas is advantageously thermally reacted with carbon monoxide (CO) and oxygen to form lithium carbonate (LiCO) in a further process step, which can take the form of, for example, a post-combustion chamber in which the lithium fluoride-containing gas is converted to lithium carbonate under highly reducing conditions at a suitable temperature.

[0023] As already explained, the target amount of fluorinating agent is such that lithium is quantitatively removed from the process at an early stage of the process while the valuable metals in the molten metal phase are concentrated. In order to achieve sufficient fluorination of lithium, the content of fluorine added to the process via the fluorinating agent should be at least 0.05% by weight, preferably at least 0.5% by weight, more preferably at least 1.0% by weight, even more preferably at least 1.5% by weight, and most preferably at least 2.0% by weight, relative to the amount of active material added to the process according to step ii).

[0024] Since some of the valuable transition metals, in particular cobalt and / or nickel, may also compete with the fluorinating agent, thereby impairing the desired separation between lithium and the valuable transition metal, the content of fluorine added to the process via the fluorinating agent does not exceed 15.0% by weight, preferably at most 12.5% ​​by weight, more preferably at most 10.0% by weight, even more preferably at most 8.5% by weight, and most preferably at most 7.5% by weight.

[0025] Advantageously, a fluorine content of 0.05 to 15.0% by weight, more preferably 0.5 to 12.5% ​​by weight, even more preferably 1.0 to 10.0% by weight, even more preferably 1.5 to 8.5% by weight, and most preferably 2.0 to 7.5% by weight, based on the amount of active material added to the process in step ii) is added to the process via the fluorinating agent. In this context, it is particularly preferred that the proportion of lithium fluoride-containing gas in the gas phase and / or in the exhaust gas is continuously detected, if necessary, so that the amount of fluorinating agent can be adjusted accordingly.

[0026] In a particularly preferred embodiment of the method, the electrolyte of the lithium-containing energy storage device is used as the fluorinating agent, which preferably comprises lithium hexafluorophosphate (LiPF6). For this purpose, it is advantageously provided that a fraction comprising the electrolyte is separated from the electrochemical energy storage device and / or from the pulverized material, and this fraction is used as the fluorinating agent according to step iii). On the one hand, this allows for a further increase in the lithium recovery rate. On the other hand, the recycling process is carried out largely on the basis of the components of the lithium-containing energy storage device.

[0027] If the fraction containing active material contains aluminum, the aluminum content may have a thermodynamically significant effect on the lithium recovery rate. To ensure an efficient process, the fraction containing active material should contain at most 10.0% by weight of aluminum, preferably at most 7.0% by weight of aluminum, more preferably at most 6.0% by weight of aluminum, even more preferably at most 5.0% by weight of aluminum, and most preferably at most 4.5% by weight of aluminum, relative to the amount of active material fed to the process according to step ii).

[0028] The oxygen partial pressure can also have a significant thermodynamic impact on lithium recovery. To achieve reducing conditions, a certain level of oxygen is required, which is oxidized to carbon monoxide along with the carbon involved in the process. However, too high an oxygen partial pressure can undesirably promote the formation of metal oxides. Therefore, the specific parameters of each process must always be adapted to the specific process conditions.

[0029] In a particularly advantageous variant, the process is carried out in the presence of a carrier gas, which may be inert, in particular in the presence of nitrogen. In another embodiment, air or oxygen-enriched air can also be used as carrier gas. A concentration of at least 300 Nm3 is used, based on the amount of 1000 kg of active material fed to the process according to step ii). 3 / h continuous flow rate, preferably at least 500 Nm 3 / h continuous flow rate, more preferably at least 750 Nm 3 / h continuous flow rate, even more preferably at least 900 Nm 3 / h continuous flow rate, most preferably at least 1000 Nm 3 / h continuous flow rate has been shown to have a particularly favorable effect on recovery. Continuous detection is used as needed to adjust the carrier gas flow rate accordingly. [Example]

[0030] example The present invention and its technical conditions will be described in more detail below using exemplary embodiments. Note that the present invention is not intended to be limited by the illustrated exemplary embodiments. In particular, unless explicitly stated otherwise, partial aspects of the illustrated embodiments and / or the matters described in the drawings may be extracted and combined with other components and findings from this specification. [Brief explanation of the drawings]

[0031] Figures 1 to 9 show the results of various examples carried out using the simulation tool Factsage®, using the FactPS, FToxid, FTmisc and FScopp databases for the calculations.

[0032] The analytically determined fraction containing active material from the crushed lithium-containing battery, with a composition according to Table 1 below, was used as input variable.

[0033] [Table 1]

[0034] In the thermodynamic calculation, mass and energy transfer, temperature, oxygen partial pressure of the carrier gas flow, and chemical properties were considered to investigate the distribution of each element in the molten slag phase, molten metal phase, and gas phase.

[0035] The following elements and compounds were identified as typical species in the gas phase: LiF;Li;(LiF)2;(LiF)3;Li2O;LiN;LiAlF4;Li2AlF5;LiO;AlF3;

[0036] Typical chemical species in the molten slag phase include the following elements and compounds: Al2O3;SiO2;CoO;NiO;MnO;Cu2O;Mn2O3;Li2O;LiAlO2;P2O5;LiF;LiAlF4; and small amounts of metal halides of Co, Cu, and Ni;

[0037] The molten metal phase contained the following elements: Co;Cu;Ni;Mn;C;P;Si;Li;Al;Fe; There was also an excess of graphite.

[0038] For the results shown in Figures 1-3, thermodynamic equilibrium calculations were performed using the parameters shown in Table 2:

[0039] [Table 2]

[0040] The results shown in Figures 1 to 3 show that, on the one hand, the conversion of lithium into the gas phase increases with increasing temperature, and, on the other hand, that an increase in the fluorine content promotes the thermodynamic process, while an increase in the Al content in the active material aggravates the thermodynamic process.

[0041] For the results shown in Figures 4 to 6, thermodynamic equilibrium calculations were performed using the parameters shown in Table 3:

[0042] [Table 3]

[0043] Comparing the results shown in Figures 1 to 3, it can be seen that the thermodynamic reaction is promoted as the continuous flow rate of the carrier gas increases.

[0044] For the results in Figures 7-9, thermodynamic equilibrium calculations were performed using the parameters in Table 4:

[0045] [Table 4]

[0046] To further investigate the effect of oxygen partial pressure, the value of oxygen partial pressure was varied while other parameters were kept constant in Examples 7 to 9. Compared with the previous examples, this example shows that lower oxygen partial pressure provides better reduction conditions and therefore favors the thermodynamic reaction. The present invention includes the following items. [Item 1] 1. A method for recycling lithium-containing electrochemical energy storage devices, particularly cells and / or batteries, comprising: i) an electrochemical energy storage device is first pulverized and a fraction containing active material is separated from the pulverized material; Here, the fraction containing the active material is carbon (C), lithium (Li), and and at least one element selected from the series including cobalt (Co), manganese (Mn), nickel (Ni), iron (Fe) and / or combinations thereof: ii) the fraction containing the active material is then fed to a smelting plant and melted in the presence of a slag former to form a molten slag phase and a molten metal phase; and iii) The method as described above, wherein lithium (Li) contained in the molten slag phase and / or the molten metal phase is converted into a gas phase by adding a fluorinating agent, and carbon (C) is converted into a gas phase by adding an oxygen-containing gas, and the converted gas is removed from the process as an exhaust gas. [Item 2] Item 3. The method according to item 1, wherein in step iii), carbon (C) is oxidized to carbon monoxide (CO) with an oxygen-containing gas. [Item 3] In a further process step, the lithium fluoride-containing gas is thermally reacted with carbon monoxide (CO) and oxygen to produce lithium carbonate (Li 2 CO 3 Item 3. The method according to item 2, wherein a hydroxyl group is formed. [Item 4] 4. The method according to any one of items 1 to 3, wherein a fluorine content of 0.05 to 15.0% by mass, based on the fraction containing the active material fed to the process according to step ii), is added to the process via a fluorinating agent. [Item 5] 5. The method according to any one of items 2 to 4, wherein the proportion of the lithium fluoride-containing gas and / or the proportion of carbon monoxide (CO) in the gas phase and / or in the exhaust gas is detected, optionally continuously. [Item 6] 6. The method according to any one of items 1 to 5, wherein the process is carried out in the presence of a carrier gas, optionally inert, in particular in the presence of nitrogen. [Item 7] The carrier gas has a flow rate of at least 300 Nm based on the amount of 1000 kg of active material fed to the process according to step ii). 3 / h, preferably at least 500 Nm 3 / h, preferably at least 750 Nm 3 / h, more preferably at least 900 Nm 3 / h, most preferably at least 1000 Nm 3 The method according to item 6, wherein the slag is injected into the refining apparatus at a flow rate of 1000 kJ / h. [Item 8] 8. The method according to item 7, wherein the flow rate of the carrier gas is detected, optionally continuously. [Item 9] 9. The method according to any one of items 1 to 8, wherein the temperature of the gas phase and / or the exhaust gas is detected, optionally continuously. [Item 10] 10. The method according to any one of items 1 to 9, wherein a fraction containing the electrolyte is separated from the electrochemical energy storage device and / or from the pulverized material, and this fraction is used as the fluorinating agent. [Item 11] The electrolyte-containing fraction was lithium hexafluorophosphate (LiPF 6 Item 11. The method according to item 10, comprising: [Item 12] 12. The method according to any one of items 1 to 11, wherein the fraction containing the active material further contains aluminum (Al) in a proportion of up to 10.0% by mass.

Claims

1. 1. A method for recycling lithium-containing electrochemical energy storage devices, particularly cells and / or batteries, comprising: i) an electrochemical energy storage device is first pulverized and a fraction containing active material is separated from the pulverized material; Here, the fraction containing the active material is composed of carbon (C), lithium (Li), and at least one element selected from the series including cobalt (Co), manganese (Mn), nickel (Ni), iron (Fe) and / or combinations thereof; ii) the fraction containing the active material is then fed to a smelting plant and melted in the presence of a slag former to form a molten slag phase and a molten metal phase; and iii) Lithium (Li) contained in the molten slag phase and / or the molten metal phase is converted into a gas phase by adding a fluorinating agent, and carbon (C) is converted into a gas phase by adding an oxygen-containing gas, and the gas is removed from the process as an exhaust gas; The method, wherein an electrolyte-containing fraction is separated from the electrochemical energy storage device and / or from the pulverized material, and this fraction is used as the fluorinating agent.

2. 2. The method of claim 1, wherein in step iii) carbon (C) is oxidized to carbon monoxide (CO) with an oxygen-containing gas.

3. The lithium fluoride-containing gas is thermally reacted with carbon monoxide (CO) and oxygen in a further process step to produce lithium carbonate (Li ２ CO ３ 3. The method of claim 2, wherein

4. 3. The method according to claim 1 or 2, wherein a fluorine content of 0.05 to 15.0% by weight, based on the fraction comprising the active material fed to the process according to step ii), is added to the process via a fluorinating agent.

5. 4. The method according to claim 2 or 3, wherein the proportion of lithium fluoride-containing gas and / or the proportion of carbon monoxide (CO) in the gas phase and / or in the exhaust gas is detected.

6. 3. The method of claim 1 or 2, wherein the process is carried out in the presence of a carrier gas.

7. The carrier gas has a flow rate of at least 300 Nm3, based on the amount of 1000 kg of active material fed to the process according to step ii). ３ / h, preferably at least 500 Nm ３ / h, more preferably at least 750 Nm ３ / h, more preferably at least 900 Nm ３ / h, most preferably at least 1000 Nm ３ 7. The method according to claim 6, wherein the molten metal is injected into the refining apparatus at a flow rate of 1000 kJ / h.

8. The method of claim 7 , wherein the flow rate of the carrier gas is detected.

9. 3. The method according to claim 1, wherein the temperature of the gas phase and / or the exhaust gas is detected.

10. The electrolyte-containing fraction is lithium hexafluorophosphate (LiPF ６ 10. The method of claim 1, comprising:

11. 3. The method according to claim 1 or 2, wherein the fraction containing the active material further comprises aluminum (Al) in a proportion of up to 10.0% by mass.

12. A method according to claim 2 or 3, wherein the proportion of lithium fluoride-containing gas and / or the proportion of carbon monoxide (CO) in the gas phase and / or in the exhaust gas is continuously detected.

13. The method of claim 1 or 2, wherein the process is carried out in the presence of an inert carrier gas, i.e., nitrogen.

14. The method of claim 7, wherein the flow rate of the carrier gas is detected continuously.

15. A method according to claim 1 or 2, wherein the temperature of the gas phase and / or exhaust gas is detected continuously.

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