Reducing metal powder for recovering valuable metal from waste lithium ion secondary battery and preparation method of reducing metal powder

Abstract

The present invention provides a reduced metal powder prepared by processing a spent lithium ion secondary battery to recover valuable metals from the spent lithium ion secondary battery in an economical and environmentally friendly manner. In order to achieve the above-mentioned purpose, the reduced metal powder of the present invention is prepared by pyrolyzing waste lithium ion secondary batteries, contains metals Ni and Co, and has magnetism.

Description

Technical Field

[0001] The present invention relates to a reduced metal powder for recycling waste lithium ion secondary batteries and a preparation method thereof, and more specifically, to a reduced metal powder containing a large amount of metal nickel and cobalt obtained by low-temperature pyrolysis of waste lithium ion secondary batteries and a preparation method thereof. Background Art

[0002] As the automotive industry transitions from internal combustion engine vehicles to electric vehicles, Europe and China, the growth axes of global electric vehicles and secondary batteries, are seeking to expand the supply of electric vehicles and gain competitiveness through carbon dioxide regulations and environmentally friendly vehicle roadmaps. As a result, the global electric vehicle market is expected to grow rapidly.

[0003] The market for scrap batteries is also expected to really grow, as EV batteries are typically discarded after 5 to 10 years of use. Global production of scrap EV batteries is expected to reach around 1.6 million tonnes by 2030, and a number of different countries, mainly in Europe, are investing heavily in developing processes to recover valuable metals from scrap batteries.

[0004] Unlike reuse, the waste battery recycling industry involves recovering valuable metals from waste batteries and reusing the valuable metals as raw materials, so both solving environmental problems and ensuring a stable supply of valuable resources are achievable.

[0005] The recycling of waste batteries usually involves extracting valuable metals through wet smelting or dry smelting processes after discharge, disassembly and pulverization. In particular, the dry smelting process, which is suitable for high-capacity processing and provides a high recovery rate, is becoming a focus.

[0006] Dry smelting involves heating the powder obtained after pulverization at high temperatures to incinerate and remove organic compounds and polymer components contained in the pulverized powder, and then extracting valuable metals through a wet process.

[0007] The dry smelting process requires a lot of time and equipment for discharge and is subsequently subjected to a complicated process, thus making it less economical in itself, and the resulting product, which is heated and discharged at a high temperature, contains a large amount of impurities and the valuable metals to be extracted are in the form of oxides, which makes it inevitable to use strong acids for wet extraction, thereby causing environmental problems. Summary of the invention

[0008] The present invention aims to provide a reduced metal powder prepared by pyrolysis of waste lithium-ion secondary batteries and suitable for recovering valuable metals in an economical and environmentally friendly manner, and a preparation method thereof.

[0009] To achieve the above object, according to an embodiment of the present invention, there is provided a reduced metal powder recovered from a waste lithium ion secondary battery, which is formed by pyrolyzing the waste lithium ion secondary battery and contains metal Ni and Co and has magnetism.

[0010] Furthermore, the saturation magnetization value of the reduced metal powder of the present invention may be 15 emu / g or more.

[0011] Furthermore, the saturation magnetization value of the reduced metal powder of the present invention may be 30 emu / g or more.

[0012] In addition, the reduced metal powder of the present invention may have metal Ni and Co in an amount of 50% by weight or more.

[0013] In addition, the reduced metal powder of the present invention may have an average particle size of 20 μm or less and a standard deviation in particle size distribution of 10 μm or less.

[0014] In addition, when the molar ratio of metal Ni to metal Co in the reduced metal powder of the present invention (M Ni / M Co , where M Ni and M Co are the molar fraction of metal Ni and the molar fraction of metal Co in the reduced metal powder) as the first molar ratio (M 1 ), and the molar ratio of Ni to Co in the positive electrode material of the spent lithium-ion secondary battery before pyrolysis (m Ni / m Co , where m ni and m Co are the molar fraction of Ni and the molar fraction of Co in the positive electrode material) is the second molar ratio (M 2 ), the difference between the first molar ratio and the second molar ratio may be less than 10% of the second molar ratio.

[0015] In addition, when pyrolysis is performed by heating the spent lithium ion battery at a temperature of 400° C. or less to induce self-heating, the reduced metal powder of the present invention can be formed.

[0016] In addition, the reduced metal powder of the present invention may not contain metal ions other than Li, Ni, Co, Mn and Al, and may not contain F. - and Cl - anion.

[0017] Meanwhile, according to an embodiment of the present invention, there is provided a metal compound prepared by wet extraction of the reduced metal powder of the present invention as a sulfide, nitride or chloride containing nickel or cobalt.

[0018] According to an embodiment of the present invention, a method for recycling waste lithium-ion secondary batteries is provided, which includes: (a) filling the waste lithium-ion secondary batteries into a pyrolysis furnace, (b) increasing the internal temperature of the pyrolysis furnace while stirring the waste lithium-ion secondary batteries to induce self-heating of the waste lithium-ion secondary batteries, (c) continuing the self-heating reaction of the waste lithium-ion secondary batteries, (d) discharging a first powder prepared after the self-heating reaction of the waste lithium-ion secondary batteries is completed, and (e) magnetically separating the first powder into a second powder driven by magnetic force and a third powder not driven by magnetic force, wherein the second powder can be the reduced metal powder of the present invention described above.

[0019] In addition, in step (a) of the method of the present invention, the spent lithium-ion secondary battery may be in an undischarged state.

[0020] In addition, in step (b) of the method of the present invention, the internal temperature may be 400° C. or lower.

[0021] In addition, in step (c) of the method of the present invention, the pyrolysis furnace may not be heated.

[0022] Additionally, step (c) of the method of the present invention may last from 10 to 24 hours.

[0023] Alternatively, step (c) of the method of the present invention may be performed in an inert gas atmosphere. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a scanning electron microscope image of the reduced metal powder of the present invention;

[0025] Figure 2 is a graph showing the measurement results of the particle size distribution of the reduced metal powder of the present invention;

[0026] Figure 3 is a graph showing the measurement results of the saturation magnetization value of the reduced metal powder of the present invention;

[0027] Figure 4 shows the X-ray diffraction analysis results of the reduced metal powder of the present invention;

[0028] Figure 5 are the transmission electron microscope images and diffraction pattern analysis results of the reduced metal powder of the present invention; and

[0029] Figure 6 These are the transmission electron microscope images and diffraction pattern analysis results of the reduced metal powder of the present invention. DETAILED DESCRIPTION

[0030] The embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily practice it. However, the present invention can be implemented in many different forms and should not be construed as limited to the embodiments set forth herein.

[0031] Throughout the specification, when an element “includes” a component, unless explicitly described to the contrary, it may mean that the element does not exclude another component but may further include another component.

[0032] The terms "about" and "substantially" and the like used throughout the specification indicate that when inherent manufacturing and material tolerances are given, such tolerances correspond to or are similar to such values, and such values ​​are for the purpose of clearly understanding the present invention or preventing an unintentional infringer from illegally using the disclosure of the present invention. In addition, throughout the specification, the term "a step in which..." or "a step of..." does not mean "a step for...".

[0033] Throughout the specification, the term “combination thereof” included in the expression in Markush form means a mixture or combination of one or more elements selected from the group consisting of the elements in the expression in Markush form, thereby meaning including at least one selected from the group consisting of the elements.

[0034] Throughout the specification, the description of "A and / or B" means "A or B, or A and B".

[0035] In a typical recycling process for extracting valuable metals from waste lithium-ion secondary batteries, pyrolysis powder is obtained through a high-temperature pyrolysis and pulverization process, and valuable metals are extracted from valuable metal oxides contained in the pyrolysis powder.

[0036] Due to the nature of the high temperature pyrolysis process, the pyrolysis powder obtained by this typical method contains impurities such as carbon and current collector materials in addition to the valuable metal oxides, so the extraction rate of valuable metals available from the whole powder is low and the extraction occurs from the oxides, thus requiring the use of strong acids.

[0037] In contrast, the reduced metal powder of the present invention is prepared by pyrolyzing waste lithium ion secondary batteries, and contains metal Ni and Co and has magnetism. In this specification, waste lithium ion secondary batteries include secondary batteries discarded after use, and secondary battery waste discarded due to defects generated during the manufacturing process.

[0038] As described above, the reduced metal powder produced by typical high-temperature pyrolysis is inevitably produced in the form of oxides due to the combination of metal ions with oxygen and contains a large amount of impurities. However, the reduced metal powder of the present invention contains metal Ni and Co, and thus has magnetic properties, enabling magnetic separation and preventing the use of environmentally harmful strong acids even in wet extraction.

[0039] The reduced metal powder of the present invention may be prepared by pyrolyzing the spent lithium ion batteries by heating the spent lithium ion batteries at a low temperature of 400° C. or lower to induce self-heating of the spent lithium ion batteries themselves.

[0040] Even at relatively low temperatures, the exothermic reaction of the positive electrode material and the electrolyte contained in the waste lithium ion secondary battery can start, so the self-heating of the waste lithium ion secondary battery can be induced even by low-temperature heating. In order to facilitate process energy consumption and metal production, while performing self-heating, the heating temperature is preferably as low as possible, so the heating temperature is 400°C or less, preferably 300°C or less, and more preferably 200°C or less.

[0041] This low-temperature pyrolysis process allows Ni and Co to exist as metals in the reduced metal powder of the present invention. In the low-temperature pyrolysis process, the carbon of the negative electrode material contained in the waste lithium-ion battery and the carbon components contained in the separator and the electrolyte are used as reducing agents for metal oxides in the pyrolysis process, thereby reducing Ni and Co contained in the positive electrode material of the waste lithium-ion secondary battery in the form of oxides to metals. In addition, the heating for pyrolysis is performed at a low temperature, so the temperature of the entire reaction is low, and therefore, the reduced Ni and Co will not be oxidized again and exist in a metallic state.

[0042] In addition, in a typical pyrolysis powder pyrolyzed at high temperature, impurities such as Cu from the negative electrode current collector, Fe from the shell, and Si and Ca from the refractory material are mixed into the pyrolysis powder. However, due to low temperature pyrolysis, such impurities may not be mixed into the reduced metal powder of the present invention. Therefore, the reduced metal powder of the present invention does not contain metal ions other than Li, Ni, Co, Mn and Al that can be obtained from the positive electrode material and the positive electrode current collector. In addition, the reduced metal powder of the present invention is not wet-processed, so it may not contain metal ions such as F - and Cl - Anions.

[0043] The reduced metal powder prepared in this way may contain a high proportion of Ni and Co in a metallic state due to low temperature pyrolysis, and in the reduced metal powder of the present invention, the sum of metallic Ni and Co may be 50 wt % or more, preferably 70 wt % or more.

[0044] Meanwhile, the reduced metal powder of the present invention has magnetic properties and may have a saturation magnetization value of 15 emu / g or more, more preferably 30 emu / g or more.

[0045] A large amount of metal Ni and Co contained in the reduced metal powder of the present invention is a ferromagnetic material, so the metal Ni and Co have a high level of saturation magnetization value, and some residual carbon and manganese oxides, etc., which do not have magnetism, contribute to lowering the saturation magnetization value. The reduced metal powder of the present invention contains a small amount of residues other than Ni and Co, so the saturation magnetization value is relatively high, preferably 15emu / g or more, more preferably 30emu / g or more.

[0046] In addition, the reduced metal powder of the present invention may have an average particle size of 20 μm or less and a standard deviation in particle size distribution of 10 μm or less.

[0047] In a typical high-temperature pyrolysis process, due to the high temperature, the obtained product agglomerates after the process, and a pulverization process is required to powder the product. However, the reduced metal powder of the present invention is obtained by a low-temperature pyrolysis process and thus has a small particle size, indicating that an additional pulverization process is not required.

[0048] In addition, the smaller the particle size of the powder for recycling waste lithium-ion batteries, the more conducive it is to extract valuable metals through post-processing. Therefore, the average particle size of the reduced metal powder of the present invention is preferably 20 μm or less. In addition, when the uniform standard deviation in the particle size distribution is 10 μm or less, it becomes easier to handle the powder.

[0049] Meanwhile, the metal Ni and Co contained in the reduced metal powder of the present invention are from the Ni and Co contained in the positive electrode material of the waste lithium ion secondary battery. Therefore, the ratio of Ni and Co depends on the ratio of the positive electrode material of the waste lithium ion secondary battery before pyrolysis. The reduced metal powder of the present invention has a very high recovery rate of Ni and Co in the waste lithium ion secondary battery, and therefore, the ratio of Ni and Co in the waste lithium ion secondary battery before pyrolysis does not show a large difference from the ratio of Ni and Co in the reduced metal powder after pyrolysis.

[0050] Therefore, when the molar ratio (M Ni / M Co , where M Ni and M Co are the molar fraction of metal Ni and the molar fraction of metal Co in the reduced metal powder) as the first molar ratio (M 1 ), and the molar ratio of Ni to Co in the positive electrode material of the spent lithium-ion secondary battery before pyrolysis (m Ni / m Co , where m ni and m Coare the molar fraction of Ni and the molar fraction of Co in the positive electrode material) is the second molar ratio (M 2 ), the difference between the first molar ratio and the second molar ratio may be 10% or less, more preferably 5% or less of the second molar ratio.

[0051] At the same time, the valuable metals nickel and cobalt in the reduced metal powder of the present invention are in a metallic state, so compared with oxides, they can be easily extracted even by weak acid treatment. Therefore, by wet extraction of the reduced metal powder of the present invention, sulfides, nitrides or chlorides containing nickel or cobalt can be effectively obtained. These metal compounds can be used again as raw materials for positive electrode materials of lithium ion secondary batteries.

[0052] The method for preparing reduced metal powder of the present invention comprises: (a) filling waste lithium ion secondary batteries into a pyrolysis furnace, (b) increasing the internal temperature of the pyrolysis furnace while stirring the waste lithium ion secondary batteries to induce self-heating of the waste lithium ion secondary batteries, (c) stopping the heating of the pyrolysis furnace and continuing the self-heating reaction of the waste lithium ion secondary batteries, (d) discharging a first powder prepared after the self-heating reaction of the waste lithium ion secondary batteries is completed, and (e) magnetically separating the first powder into a second powder driven by magnetic force and a third powder not driven by magnetic force, and the second powder can be the reduced metal powder of the present invention described above.

[0053] As described above, the reduced metal powder of the present invention is achieved by low temperature heating to induce self-heating and the resulting pyrolysis. The powder obtained after the pyrolysis is completed can be discharged from the pyrolysis furnace and magnetically separated to obtain the reduced metal powder of the present invention containing Ni and Co as metal components.

[0054] In this case, the waste lithium ion secondary battery may be put into the pyrolysis furnace while not being discharged, and such undischarged waste lithium ion secondary battery may easily generate self-heating even when heated at a low temperature, thereby causing pyrolysis.

[0055] In particular, since no discharge treatment is required, unlike a typical pyrolysis method, no equipment and process for discharge are required, which can greatly reduce the process cost.

[0056] In addition, in the method for recycling waste lithium-ion batteries of the present invention, heating for pyrolysis can be performed even at a temperature below 400°C, so the energy cost for pyrolysis can also be reduced. Heating for pyrolysis can also be performed at a temperature below 300°C, and can be below 200°C.

[0057] After the self-heating starts after heating, the artificial heating of the pyrolysis furnace can be stopped and the self-heating reaction of the waste lithium-ion secondary battery can be continued. The reaction can last for 10 to 24 hours. When the reaction time is too short, it is very likely that impurities will be generated due to the rapid reaction, and when the reaction time is too long, the process productivity decreases, which is undesirable. The reaction time can be controlled by adjusting the internal temperature and atmosphere in the pyrolysis furnace in steps (b) and (c).

[0058] After the self-heating is completed, the pyrolysis reaction may be performed in an inert gas atmosphere, and nitrogen, argon, and the like may be used as the inert gas.

[0059] Hereinafter, analysis results of the reduced metal powder of the present invention will be described with reference to the accompanying drawings.

[0060] Figure 1 is a scanning electron microscope image of the reduced metal powder of the present invention, Figure 2 It is the result of measuring the particle size of the reduced metal powder. The reduced metal powder is usually spherical powder with an average particle size of 14.8 μm and a narrow distribution.

[0061] Figure 3 It is a graph showing the measurement results of the saturation magnetization value of the reduced metal powder before and after the magnetic separation of the reactant discharged after the reaction is completed in the pyrolysis furnace.

[0062] It was observed that the saturation magnetization value of the powder after magnetic separation (i.e., the reduced metal powder of the present invention) was significantly increased compared to the powder before magnetic separation. The powder after magnetic separation became the reduced metal powder of the present invention and contained a large amount of metal Ni and metal Co, and therefore had a high saturation magnetization value (34.02emu / g).

[0063] Figure 4 : is a graph showing the results of X-ray diffraction analysis of the reduced metal powder of the present invention. It was found that the peaks of metal Ni (fcc structure) and metal Co (hcp structure) were the strongest, so the content of metal Ni and Co was high. In addition, lithium carbonate (Li 2 CO 3 ), MnO and Al, etc.

[0064] Figure 5 and 6 The transmission electron microscope image and diffraction pattern analysis results of the reduced metal powder of the present invention are shown. In the diffraction pattern, metal Ni having an fcc structure is observed, such as Figure 4 The XRD results are shown in .

[0065] According to the present invention, reduced metal powders prepared by pyrolyzing spent lithium-ion secondary batteries allow for the recovery of valuable metals in an economical and environmentally friendly manner.

Claims

1. A reduced metal powder recovered from a waste lithium ion secondary battery, the reduced metal powder being prepared by pyrolyzing the waste lithium ion secondary battery and containing metals Ni and Co and having magnetism.

2. The reduced metal powder according to claim 1, The reduced metal powder has a saturation magnetization value of 15 emu / g or more.

3. The reduced metal powder according to claim 1, The reduced metal powder has a saturation magnetization value of 30emu / g or more.

4. The reduced metal powder according to claim 1, The amount of the metal Ni and Co is 50 wt % or more.

5. The reduced metal powder according to claim 1, The reduced metal powder has an average particle size of 20 μm or less and a standard deviation in particle size distribution of 10 μm or less.

6. The reduced metal powder according to claim 1, Wherein, when the molar ratio of metal Ni to metal Co in the reduced metal powder (M Ni / M Co , where M Ni and M Co The molar fraction of metal Ni and the molar fraction of metal Co in the reduced metal powder are respectively the first molar ratio (M1), and the molar ratio of Ni to Co in the positive electrode material of the waste lithium ion secondary battery before pyrolysis (m Ni / m Co , where m ni and m Co When the molar fraction of Ni and the molar fraction of Co in the positive electrode material are respectively the second molar ratio (M2), the difference between the first molar ratio and the second molar ratio is less than 10% of the second molar ratio.

7. The reduced metal powder according to claim 1, The pyrolysis is performed by heating the spent lithium-ion batteries at a temperature below 400° C. to induce self-heating.

8. The reduced metal powder according to claim 1, The reduced metal powder does not contain metal ions other than Li, Ni, Co, Mn and Al, and does not contain F - and Cl - anion.

9. A metal compound prepared by wet extraction of the reduced metal powder according to any one of claims 1 to 8 as a sulfide, nitride or chloride containing nickel or cobalt.

10. A method for recycling waste lithium-ion secondary batteries, the method comprising: (a) filling the waste lithium-ion secondary batteries into a pyrolysis furnace; (b) increasing the internal temperature of the pyrolysis furnace while stirring the spent lithium ion secondary batteries to induce self-heating of the spent lithium ion secondary batteries; (c) continuing the self-heating reaction of the waste lithium-ion secondary battery; (d) discharging a first powder prepared after the self-heating reaction of the waste lithium ion secondary battery is completed; and (e) magnetically separating the first powder into a second powder driven by magnetic force and a third powder not driven by magnetic force, The second powder is the reduced metal powder according to any one of claims 1 to 8.

11. The method according to claim 10, Wherein in the step (a), the waste lithium-ion secondary battery is in an undischarged state.

12. The method according to claim 10, Wherein in the step (b), the internal temperature is below 400°C.

13. The method according to claim 10, Wherein in the step (c), the pyrolysis furnace is not heated.

14. The method according to claim 10, The step (c) lasts for 10 to 24 hours.

15. The method according to claim 10, Wherein the step (c) is carried out in an inert gas atmosphere.

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