Method for recycling waste lithium ion secondary battery and electrode raw material obtained thereby

Abstract

The purpose of the present invention is to provide: a method for economically and environmentally-friendly recovery of an electrode raw material for positive and negative electrodes from a spent lithium ion secondary battery, said electrode raw material being formed by pyrolyzing a spent lithium ion secondary battery; and an electrode raw material for positive and negative electrodes obtained thereby. In order to achieve the purpose, the recycling method of the waste lithium ion secondary battery according to the present invention may include (a) filling the waste lithium ion secondary battery into a pyrolyzing furnace, (b) increasing an internal temperature of the pyrolyzing furnace to induce self-heating of the waste lithium ion secondary battery, (c) maintaining a self-heating reaction of the waste lithium ion secondary battery, and (e) reducing the internal temperature of the pyrolyzing furnace to induce self-heating of the waste lithium ion secondary battery. (d) discharging a first powder formed after the completion of the self-heating reaction of the waste lithium ion secondary battery, and (e) injecting the first powder into water, dissolving a lithium component contained in the first powder, and separating and recovering an aqueous lithium solution, a precipitate precipitated in the aqueous lithium solution, and a float on the surface of the aqueous lithium solution, respectively.

Description

Technical Field

[0001] The present invention relates to a method for recycling waste lithium-ion batteries and electrode raw materials obtained thereby, and more particularly to a method for recycling electrode raw materials in an environmentally friendly and economical manner by pyrolysis of waste lithium-ion secondary batteries and a separation process using water, and electrode raw materials obtained thereby. Background Art

[0002] In line with the automotive industry's shift from internal combustion engine vehicles to electric vehicles, Europe and China, which are the growth axes of global electric vehicles and secondary batteries, are seeking to expand the supply of electric vehicles and ensure competitiveness through CO2 regulations and green vehicle roadmaps. As a result, the global electric vehicle market is expected to grow rapidly.

[0003] Typically, electric vehicle batteries are discarded after 5-10 years of use, and the market for scrap batteries is expected to become serious. Global generation of scrap electric vehicle batteries is expected to be around 1.6 million tonnes by 2030, and in many countries, mainly in Europe, large-scale investments are being made to develop processes to recover valuable metals from scrap batteries.

[0004] In the waste battery recycling industry, unlike reuse, recovering valuable metals from waste batteries and reusing them as raw materials can simultaneously solve environmental problems and stably secure valuable raw materials.

[0005] The recycling of waste batteries is usually carried out through the following process: extraction of valuable metals through discharge, decomposition and pulverization, followed by a subsequent wet smelting process (smelting process) or a dry smelting process. The dry smelting process, which is suitable for large-scale processing and has high recovery efficiency, has attracted much attention.

[0006] According to the dry smelting process, the powder obtained by pulverization is heated at a high temperature to burn and remove organic compounds and polymer components contained in the pulverized powder, the resultant is pulverized again, and valuable metals are extracted by a wet method using a strong acid.

[0007] The dry smelting process requires a lot of time and equipment for discharge and pulverization, and the subsequent complicated process becomes less economical, heating at high temperature causes a large amount of impurities in the discharged resultant, thereby reducing the extraction ratio of valuable components obtained from the entire powder, and the resultant existing in a bulk state inevitably requires pulverization again and the use of strong acid to extract valuable components, thereby causing environmental problems. Summary of the invention

[0008] The object of the present invention is to provide a method for economically and environmentally friendly recovering electrode raw materials for positive and negative electrodes from waste lithium ion secondary batteries, and the electrode raw materials for positive and negative electrodes obtained thereby, wherein the electrode raw materials are formed by pyrolyzing waste lithium ion secondary batteries.

[0009] To achieve this purpose, the method for recycling waste lithium-ion secondary batteries of the present invention may include: (a) filling the waste lithium-ion secondary batteries into a pyrolysis furnace, (b) increasing the internal temperature of the pyrolysis furnace to induce self-heating of the waste lithium-ion secondary batteries, (c) maintaining the self-heating reaction of the waste lithium-ion secondary batteries, (d) discharging a first powder formed after the self-heating reaction of the waste lithium-ion secondary batteries is completed, and (e) injecting the first powder into water to dissolve the lithium component contained in the first powder, and separating and recovering the lithium aqueous solution, the precipitate precipitated in the lithium aqueous solution, and the floating matter on the surface of the lithium aqueous solution, respectively.

[0010] In addition, in the method for recycling waste lithium-ion secondary batteries according to the embodiment of the present invention, the temperature of the water used to inject the first powder in step (e) may be 30° C. or lower.

[0011] In addition, in the method for recycling waste lithium-ion secondary batteries according to the embodiment of the present invention, microbubbles having a size of 20 μm or less may be injected into the slurry formed after injecting the first powder into water in step (e).

[0012] In addition, the method for reusing a waste lithium-ion secondary battery according to an embodiment of the present invention may further include evaporating water in the lithium aqueous solution to recover lithium carbonate.

[0013] In addition, the method for recycling a waste lithium-ion secondary battery according to an embodiment of the present invention may further include injecting an alkali into the lithium aqueous solution to increase the pH, and precipitating and recovering the lithium component as lithium hydroxide.

[0014] In addition, the method for reusing a waste lithium-ion secondary battery according to an embodiment of the present invention may further include injecting the precipitate into an acidic aqueous solution to recover a metal aqueous solution in which a metal component contained in the precipitate is dissolved.

[0015] In addition, in the method for recycling a waste lithium-ion secondary battery according to an embodiment of the present invention, the precipitate may contain metallic nickel and cobalt.

[0016] In addition, in the method for recycling a waste lithium-ion secondary battery according to the embodiment of the present invention, the precipitate may contain metallic iron.

[0017] In addition, in the method for recycling waste lithium-ion secondary batteries according to the embodiment of the present invention, water may be injected into the pyrolysis furnace in step (a).

[0018] In addition, in the method for recycling waste lithium ion secondary batteries of an embodiment of the present invention, the injection amount of water in step (a) can be 1 to 10 parts by mass based on 100 parts by mass of the weight of the positive electrode material contained in the waste lithium ion secondary batteries filled in the pyrolysis furnace.

[0019] In addition, in the method for recycling waste lithium ion secondary batteries according to the embodiment of the present invention, the waste lithium ion secondary batteries in step (a) may be in an undischarged state.

[0020] In addition, in the method for recycling waste lithium ion secondary batteries according to the embodiment of the present invention, the waste lithium ion secondary batteries in step (a) may be in an unshredded state.

[0021] In addition, in the method for recycling waste lithium ion secondary batteries according to the embodiment of the present invention, the waste lithium ion secondary batteries in step (a) may include waste lithium ion secondary batteries discarded as defects in the manufacturing process of lithium ion secondary batteries.

[0022] In addition, in the method for recycling waste lithium ion secondary batteries according to the embodiment of the present invention, the waste lithium ion secondary batteries in step (a) may be decomposed and pulverized, and may include waste lithium ion secondary batteries in a powder state.

[0023] In addition, in the method for recycling waste lithium-ion secondary batteries according to the embodiment of the present invention, the internal temperature in step (b) may be 400° C. or lower.

[0024] In addition, in the method for recycling waste lithium-ion secondary batteries according to the embodiment of the present invention, the pyrolysis furnace may not be heated in step (c).

[0025] In addition, in the method for recycling waste lithium-ion secondary batteries according to an embodiment of the present invention, step (c) may last for 10 to 24 hours.

[0026] In addition, in the method for recycling waste lithium-ion secondary batteries according to the embodiment of the present invention, step (c) may be performed in an inert gas atmosphere.

[0027] According to the present invention, there can be provided a metal powder recovered from a waste lithium ion secondary battery as a precipitate recovered by the above-mentioned method for recycling a waste lithium ion secondary battery, the metal powder containing Ni and Co and having magnetism.

[0028] The metal powder according to the embodiment of the present invention may have a saturation magnetization value of 15 emu / g or more.

[0029] The average particle size of the metal powder according to the embodiment of the present invention measured by a particle size analyzer using laser diffraction may be 20 μm or less, and the standard deviation in the particle size distribution may be 10 μm or less.

[0030] In the metal powder of the embodiment of the present invention, if the molar ratio (M Ni / M Co , M Ni and M Co The molar ratio of Ni to Co in the positive electrode material of the waste lithium-ion secondary battery before pyrolysis is (m Ni / m Co , m Ni and m Co are the molar fraction of Ni and the molar fraction of Co in the positive electrode material, respectively) is the second molar ratio (M2), then the difference between the first molar ratio and the second molar ratio may be less than 10% of the second molar ratio.

[0031] The metal powder of the embodiment of the present invention may not contain metal ions other than metal ions of Li, Ni, Co, Fe, and Al, and may not contain F. - and Cl - anion.

[0032] According to the present invention, there can be provided an iron powder recovered from a waste lithium ion secondary battery as a precipitate recovered from the above-mentioned method for recycling waste lithium ion secondary batteries and containing metallic iron or iron oxide.

[0033] According to the present invention, there can be provided a carbon powder recovered from a waste lithium ion secondary battery as a floating material recovered from the above-mentioned method for recycling waste lithium ion secondary batteries, and comprising graphite, or graphite and silicon dioxide.

[0034] The average particle size of the carbon powder according to the embodiment of the present invention measured by a particle size analyzer using laser diffraction may be 20 μm or less, and the standard deviation in the particle size distribution may be 10 μm or less.

[0035] According to the present invention, there can be provided a waste lithium ion secondary battery recycling powder comprising lithium carbonate, metal nickel and metal cobalt as a first powder recovered by a method for recycling waste lithium ion secondary batteries.

[0036] Beneficial Effects

[0037] The method for recycling waste lithium-ion secondary batteries of the present invention is both economical and environmentally friendly, and can improve the recycling efficiency of waste lithium-ion secondary batteries and solve environmental problems generated in the recycling process.

[0038] In addition, an economically feasible positive electrode material or negative electrode material can be prepared from a raw material for a positive electrode or a negative electrode using the valuable element components obtained according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a flow chart illustrating a method for recycling waste lithium-ion secondary batteries according to an embodiment of the present invention;

[0040] Figure 2 Schematic diagram illustrating a process for obtaining lithium carbonate in a method for recycling waste lithium-ion secondary batteries according to an embodiment of the present invention;

[0041] Figure 3 1 is a diagram showing the results of X-ray diffraction analysis of lithium carbonate obtained by the method for recycling waste lithium-ion secondary batteries according to an embodiment of the present invention;

[0042] Figure 4 is a diagram showing the results of particle size analysis using laser diffraction on a precipitate obtained by the method for recycling a waste lithium-ion secondary battery according to an embodiment of the present invention;

[0043] Figure 5 is a graph showing the measurement results of saturation magnetization values ​​of a powder obtained immediately after pyrolysis and a precipitate recovered after treatment in water in a method for recycling a waste lithium-ion secondary battery according to an embodiment of the present invention;

[0044] Figure 6 A transmission electron microscope image and a diffraction pattern analysis result of a precipitate obtained by the method for recycling a waste lithium-ion secondary battery according to an embodiment of the present invention are shown; and

[0045] Figure 7 The transmission electron microscope image and diffraction pattern analysis results of the precipitate obtained by the method for recycling a waste lithium-ion secondary battery according to an embodiment of the present invention are shown. DETAILED DESCRIPTION

[0046] Hereinafter, the embodiments of the present application will be explained in detail with reference to the accompanying drawings so that a person skilled in the art can easily carry out the present application. However, the present application can be implemented in various different types and is not limited to the embodiments explained herein.

[0047] Throughout the specification, when a part is referred to as “comprising” any components, it means that the part may further include other components, rather than excluding other components, unless otherwise specified.

[0048] The terms "about" and "substantially" and the like used herein are used in the sense of approximating a numerical value when manufacturing and material errors specific to the meaning are given, and are used to prevent unscrupulous persons from abusing the disclosure that gives exact or absolute values ​​for the purpose of helping to understand the present invention. In addition, the term "to step" or "step of to" used throughout the specification does not mean "step for to".

[0049] Throughout the specification, the term "combination thereof" included in the expression of Markush form means a mixture or combination of more than one selected from the group consisting of the components described in the expression of Markush form, and means including more than one selected from the group consisting of the components.

[0050] Throughout the specification, the term "A and / or B" means "A or B, or A and B".

[0051] The method for recycling waste lithium ion secondary batteries provided by the present invention comprises: (a) filling waste lithium ion secondary batteries into a pyrolysis furnace, (b) increasing the internal temperature of the pyrolysis furnace to induce self-heating of the waste lithium ion secondary batteries, (c) maintaining the self-heating reaction of the waste lithium ion secondary batteries, (d) discharging a first powder formed after the self-heating reaction of the waste lithium ion secondary batteries is completed, and (e) injecting the first powder into water to dissolve the lithium component contained in the first powder, and separating and recovering a lithium aqueous solution, a precipitate precipitated in the lithium aqueous solution, and a floating object on the surface of the lithium aqueous solution, respectively.

[0052] In the method for recycling waste lithium ion secondary batteries of the present invention, the battery is heated at a relatively low temperature to induce pyrolysis by self-heating of the positive electrode material, binder or electrolyte contained in the battery. In particular, a uniform reaction can be induced by stirring during the injection of the waste lithium ion secondary battery into the pyrolysis furnace and the increase of the internal temperature.

[0053] Meanwhile, the black mass, which is a powder formed by decomposing and pulverizing the waste lithium ion secondary battery, can also be self-heated by the positive electrode material, binder or electrolyte in the battery, and can induce a reaction by low temperature heating. In this case, the black mass may preferably be a black mass that is not heated in the treatment process of the waste lithium ion battery.

[0054] In order to make the self-heating reaction proceed smoothly, the waste lithium ion secondary battery can be injected into the pyrolysis furnace in an undischarged state, and then the temperature can be increased. The undischarged waste lithium ion secondary battery has a high energy state, and self-heating can easily occur by heating at a low temperature to achieve pyrolysis. In particular, since no discharge treatment is required, unlike the conventional pyrolysis method, equipment for discharge and a process for discharge are not required, and the process cost can be significantly saved.

[0055] In addition, the waste lithium ion secondary battery injected in the recycling method of the waste lithium ion secondary battery of the present invention can be in an un-crushed state. In conventional recycling methods, the waste lithium ion secondary battery is heated to a high temperature after crushing, but in the recycling method of the present invention, the battery is injected into a pyrolysis furnace in an un-crushed state. After completing the self-heating reaction, the positive electrode material, negative electrode material or electrolyte in the waste lithium ion secondary battery can be decomposed into a powder state, but the shell or current collector of the battery can maintain its shape. Thus, after self-heating at low temperature, the crushed positive electrode material or negative electrode material can be easily separated from the shell or current collector that maintains the shape. Since equipment and process for crushing are not required, a reduction in process cost can be achieved.

[0056] Meanwhile, the waste lithium ion secondary battery injected in the method for recycling waste lithium ion secondary batteries of the present invention may be a black mass as a powder formed by decomposing and crushing the waste lithium ion secondary battery. The black mass may also be self-heated by the positive electrode material, adhesive or electrolyte in the battery, and may induce a reaction by low temperature heating. In this case, the black mass may preferably be a black mass that is not heated in the treatment process of the waste lithium ion battery.

[0057] Meanwhile, the waste lithium ion secondary battery injected into the method for recycling waste lithium ion secondary batteries of the present invention may include waste lithium ion secondary batteries discarded as defects in the manufacturing process of the secondary battery. The manufacturing process of the secondary battery can be divided into a plating process, an assembly process or a formation process, etc., and the waste lithium ion secondary battery as intermediate waste, including the electrode plate on which the positive electrode material is coated in each process, can be reused by the method for recycling waste lithium ion secondary batteries of the present invention.

[0058] In conventional high-temperature pyrolysis processes, the entirety of the housing or current collector contained in the waste lithium-ion battery and the positive electrode material and the negative electrode material may form a bulk. Therefore, in order to separate valuable components from the bulk, the bulk needs to be subjected to a crushing process after the heating process and before the heating process, and a large amount of impurities may be included. On the contrary, by the recycling method of the present invention, only the valuable element components contained in the positive electrode material or the negative electrode material can be easily crushed and separated by the self-heating process.

[0059] In addition, in the recycling method of the present invention, pyrolysis is performed by self-heating of materials in the waste lithium-ion secondary battery, which does not require temperature increase and can save energy costs compared to conventional recycling methods.

[0060] After the self-heating is completed, the metal elements (such as nickel, cobalt, manganese, aluminum and iron) that may be contained in the positive electrode material of the waste lithium ion secondary battery may be contained in the first powder recovered in the form of metal or oxide. In particular, nickel, cobalt or iron, etc. may be partially reduced to metal nickel, cobalt or iron, etc. through a thermal carbon reduction reaction by carbon components such as separators and negative electrode materials contained in the waste lithium ion secondary battery, and may be contained in the first powder. At the same time, the lithium in the positive electrode material and the electrolyte may be converted into lithium carbonate (Li2CO3) during the self-heating reaction, the negative electrode material may be partially decomposed, volatilized and removed, and the remaining part may remain in the first powder in the form of graphite or silicon dioxide.

[0061] If the first powder in which various valuable components remain is injected into pure water, the lithium carbonate contained is first dissolved in water to form a lithium aqueous solution. In addition, nickel, cobalt, manganese, aluminum, or iron, etc. contained in the first powder in a metal or oxide state precipitates and settles at the bottom. Moreover, graphite and silicon dioxide, which are constituent components of the negative electrode material, are materials with low density and float on the water surface.

[0062] Therefore, in step (e), the valuable element components can be recovered from the waste lithium ion secondary battery as a lithium aqueous solution, a precipitate and a floating object, respectively. Lithium can be recovered from the lithium aqueous solution, and nickel, cobalt, manganese, aluminum or iron as a raw material of the positive electrode material can be recovered from the precipitate. In addition, graphite and / or silicon dioxide as a material of the negative electrode material can be recovered from the floating objects on the water surface.

[0063] The method for recycling waste lithium ion secondary batteries of the present invention is as follows Figure 1 The flowchart is shown in FIG.

[0064] Meanwhile, if the temperature of the water injected into the first powder is low, it is advantageous for the lithium aqueous solution because the solubility of lithium carbonate in water increases at low temperatures. Therefore, in the method for recycling waste lithium-ion secondary batteries of the present invention, the temperature of the water injected into the first powder is preferably 30°C or less, more preferably 25°C or less, and even more preferably 10°C or less. If the temperature of the water is low, it is advantageous, but considering the process cost, it is advantageous to control the temperature below an appropriate level.

[0065] In addition, in order to effectively and quickly dissolve lithium and to effectively separate floating objects and precipitates, microbubbles of 20 microns or less may be supplied to the slurry formed by injecting the first powder into water. Through the supplied microbubbles, the flow of the slurry may occur in the slurry, rapid dissolution of lithium carbonate may be induced, and effective separation into precipitates and floating objects may be facilitated. The size of the microbubbles is preferably 20 microns or less, because the larger the size, the microbubbles may rise to the surface of the slurry, and it is difficult to obtain the effect of the microbubbles.

[0066] Meanwhile, the slurry formed after injecting the first powder into water can be effectively separated into a lithium aqueous solution in which lithium carbonate is dissolved, a floating substance, and a precipitate by stirring or treating with ultrasonic waves.

[0067] To recover lithium from the aqueous lithium solution, all water contained in the aqueous lithium solution can be evaporated to recover lithium carbonate (Li2CO3). The lithium carbonate contained in the first powder can be dissolved in water, the aqueous lithium solution can be separated, and then the water can be removed again to recover pure lithium carbonate.

[0068] Figure 2 Schematic diagram illustrating a method of obtaining pure lithium carbonate by dissolving a first powder (obtained by completing pyrolysis according to the method for recycling waste lithium-ion secondary batteries of the present invention), separating a lithium aqueous solution, and evaporating water from the lithium aqueous solution.

[0069] In addition, recovery of lithium from a lithium aqueous solution may be performed by injecting an alkali (eg, sodium hydroxide and calcium hydroxide) into the aqueous solution to increase pH and precipitate lithium ions contained in the aqueous solution into the form of lithium hydroxide (LiOH).

[0070] Meanwhile, in the method for recycling waste lithium ion secondary batteries of the present invention, water can be injected into the pyrolysis furnace together with the waste lithium ion secondary batteries in step (a). The injected water can react with the carbon components in the waste lithium ion secondary batteries to generate methane (CH4) gas, thereby making it easier to reduce the nickel or cobalt components contained in the positive electrode material in the waste lithium ion batteries.

[0071] Even if the amount of water injected is small, sufficient effect can be obtained, and it can be 1 to 10 parts by mass based on 100 parts by mass of the weight of the positive electrode material contained in the waste lithium ion secondary battery. If the amount is too small, it is difficult to obtain the methane gas effect, and if the amount is too large, it is not preferred because the energy cost for pyrolysis increases.

[0072] In addition, in the method for recycling waste lithium-ion secondary batteries of the present invention, heating for pyrolysis can be performed at 400°C or less, and energy costs for pyrolysis can also be saved. Heating for pyrolysis can also be 300°C or less, and 200°C or less.

[0073] After heating and starting self-heating, the artificial heating of the pyrolysis furnace is 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. If the reaction time is too short, the possibility of producing impurities may be high due to the rapid reaction, and if the reaction time is too long, the process productivity may be undesirably deteriorated. The control of the reaction time can be carried out by controlling the internal temperature and atmosphere in the pyrolysis furnace in steps (b) and (c).

[0074] After self-heating, the pyrolysis reaction may be performed in an inert gas atmosphere, and nitrogen, helium, or argon may be used as the inert gas.

[0075] At the same time, in the precipitate recovered in step (e), nickel, cobalt, manganese, aluminum or iron, etc., which are positive electrode raw materials, can be recovered, and by dissolving the precipitate in an acid (such as sulfuric acid, hydrochloric acid and nitric acid), valuable metal components can be separated by a wet method. If a ternary positive electrode material (NCA or NCM, etc.) is applied to a waste lithium-ion secondary battery, nickel, cobalt, manganese and aluminum can be recovered, and if an iron phosphate positive electrode material (LFP) is used, iron can be recovered.

[0076] In the conventional method of performing high-temperature pyrolysis, the valuable metal components contained in the positive electrode material cannot be separated by water, but are separated by wet treatment via pulverization and using a strong acid. However, in the recycling method of the present invention, only the valuable metal components of the positive electrode material can be simply separated by water. Therefore, the precipitate of the present invention has a powder type and does not contain metal ions other than ions of Li, Ni, Co, Mn, Al, and Fe, and since no wet treatment is performed, it may not contain ions such as SO4 2- 、F - and Cl - Anions.

[0077] In the recycling method of the present invention, if the target positive electrode material of the waste lithium ion secondary battery is a ternary positive electrode material, the recovered precipitate may particularly include metal nickel and cobalt, and may be a metal powder having magnetism. Through a pyrolysis process at a low temperature, a negative electrode material or a conductive material in the battery may undergo a thermal carbon reduction reaction, and the nickel and cobalt contained in the positive electrode material may be reduced to a metal phase.

[0078] The metal powder may have magnetism, and its saturation magnetization value may be 15 emu / g or more, more preferably 30 emu / g or more.

[0079] The metal Ni and Co contained in high content in the metal powder as the precipitate of the present invention are ferromagnetic substances and have a high degree of saturation magnetization value. Some residual non-magnetic aluminum or manganese oxides, etc. can play a role in reducing the saturation magnetization value. The metal powder of the present invention has a low content of residues other than Ni and Co, and the saturation magnetization value is relatively high, preferably 15emu / g or more, more preferably 30emu / g or more. By utilizing magnetism, the oxide contained in the precipitate can be removed by magnetic separation, and only the metal component can be further separated and selected.

[0080] In addition, the metal powder of the present invention may have an average particle size of 20 μm or less as measured by a particle size analyzer using laser diffraction, and a standard deviation in particle size distribution may be 10 μm or less.

[0081] In the conventional high-temperature pyrolysis process, due to the high-temperature process, a mass of the resultant may be formed after processing, so for powderization, a pulverization process is inevitable. However, since the metal powder of the present invention is obtained by a low-temperature pyrolysis process, the particle size may be smaller and an additional pulverization process is not required.

[0082] In addition, if the particle size of the metal powder for recycling waste lithium-ion secondary batteries is reduced, it may be advantageous to extract valuable metals through post-processing. Therefore, the average particle size of the metal powder of the present invention is preferably 20 μm or less. In addition, the standard deviation in the particle size distribution is 10 μm or less and uniform, and the powder may be easy to handle.

[0083] Meanwhile, the metal Ni and Co contained in the metal powder of the present invention are derived from the Ni and Co contained in the positive electrode material of the waste lithium ion secondary battery. Therefore, their ratio follows the composition of the positive electrode material of the waste lithium ion secondary battery before pyrolysis. The metal powder of the present invention is very efficient in recovering Ni and Co from waste lithium ion secondary batteries, and the ratio of Ni and Co in the waste lithium ion secondary battery before pyrolysis may not be much different from the ratio of Ni and Co in the metal powder after pyrolysis.

[0084] Therefore, if the molar ratio of metal Ni to metal Co in the metal powder of the present invention (M Ni / M Co , M Ni and M Co The molar ratio of Ni to Co in the positive electrode material of the waste lithium-ion secondary battery before pyrolysis is (m Ni / m Co , m Ni and m Co The molar fraction of Ni and the molar fraction of Co in the positive electrode material of the waste lithium-ion secondary battery are respectively the molar fraction of Ni and the molar fraction of Co in the positive electrode material of the waste lithium-ion secondary battery) is the second molar ratio (M2), then the difference between the first molar ratio and the second molar ratio can be less than 10% of the second molar ratio, more preferably less than 5%.

[0085] In addition, in the metal powder of the present invention, since the valuable metals of nickel and cobalt are in a metallic state, they can be easily extracted by only weak acid treatment compared to oxides. Therefore, by wet extraction of the metal reduction powder of the present invention, sulfides, nitrides or chlorides including nickel or cobalt can be effectively obtained. This metal compound can be used again as a raw material for the positive electrode material of a lithium ion secondary battery.

[0086] In addition, in the recycling method of the present invention, if the target positive electrode material of the waste lithium ion secondary battery is an iron phosphate-based positive electrode material, the recovered precipitate can be a metal powder including metallic iron or iron oxide. As with the ternary positive electrode material, the iron contained in the positive electrode material can be contained in the precipitate in a reduced metal phase or an iron oxide state through a carbon thermal reduction reaction of pyrolysis at low temperature.

[0087] Meanwhile, the floating matter recovered in the recycling method of the present invention may be a carbon powder including graphite, or graphite and silicon dioxide having a low density as a negative electrode material. The carbon powder floating matter may be captured and dried, and graphite or silicon that can be reused as a negative electrode material may be recovered.

[0088] The carbon powder may also have an average particle size of 20 μm or less as measured by a particle size analyzer using laser diffraction, and a standard deviation in particle size distribution may be 10 μm or less.

[0089] [Example]

[0090] According to the recycling method of the present invention, a waste lithium ion secondary battery using a ternary (NCM) positive electrode material to form a positive electrode is processed to obtain a first powder. The undischarged waste lithium ion secondary battery is injected into a pyrolysis furnace, and while the temperature of the hot line in the pyrolysis furnace is controlled below 300°C, a self-heating reaction of the waste lithium ion secondary battery is induced. After the self-heating reaction starts, the internal temperature is controlled so that the pyrolysis reaction lasts for 12 hours. After the reaction is completed, the crushed material is separated and recovered to obtain a first powder.

[0091] The obtained first powder was poured into water maintained at 4° C. and treated with ultrasonic waves. The solution thus treated was allowed to stand for a certain period of time to separate the precipitate and the floating matter in the solution. Then, the precipitate, the lithium aqueous solution and the floating matter were separated by filtration.

[0092] From the lithium aqueous solution thus obtained, water was removed by evaporation to obtain lithium carbonate. The lithium carbonate powder thus obtained was subjected to component analysis using X-ray diffraction analysis and inductively coupled plasma-optical emission spectroscopy (ICP-OES). Figure 3 The X-ray diffraction analysis results are shown, and it can be found that the lithium carbonate powders obtained through the two experiments are all pure lithium carbonate, and no impurities other than lithium are found in the ICP-OES results (see Table 1).

[0093] [Table 1]

[0094] Li Ni Co Mn Al Sample 1 20.41 Not Detected Not Detected Not Detected Not Detected Sample 2 18.34 Not Detected Not Detected Not Detected Not Detected

[0095] Figure 4The results of measuring the particle size of the recovered precipitate are shown. The metal powder precipitate was mostly spherical powder, and the average particle size of the metal reduction powder was 14.8 μm, and its distribution was not wide.

[0096] Figure 5 is a graph showing the measurement results of the saturation magnetization values ​​of the first powder discharged after the reaction is completed in the pyrolysis furnace and the precipitate dissolved in water and separated from the water.

[0097] It can be found that the saturation magnetization value of the metal powder precipitate is significantly increased compared to the powder before dissolution. Compared with the first powder, in the precipitate, lithium carbonate and graphite and silicon as negative electrode materials are separated into lithium aqueous solution and floating materials, respectively, and metal Ni and metal Co are contained in high content, thus showing a high saturation magnetization value (34.02emu / g).

[0098] Figure 6 and Figure 7 The transmission electron microscope image and diffraction pattern analysis results of the precipitate of the present invention are shown. In the diffraction pattern, metal Ni with an fcc structure can be confirmed.

Claims

1. 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 to induce self-heating of the spent lithium-ion secondary battery; (c) maintaining a self-heating reaction of the waste lithium-ion secondary battery; (d) discharging a first powder formed after the self-heating reaction of the waste lithium ion secondary battery is completed; and (e) injecting the first powder into water to dissolve the lithium component contained in the first powder, and separating and recovering the lithium aqueous solution, the precipitate precipitated in the lithium aqueous solution, and the floating matter on the surface of the lithium aqueous solution.

2. The method for recycling waste lithium-ion secondary batteries according to claim 1, The temperature of the water used to inject the first powder in step (e) is below 30°C.

3. The method for recycling waste lithium-ion secondary batteries according to claim 1, The microbubbles having a size of less than 20 micrometers are injected into the slurry formed after the first powder is injected into the water in step (e).

4. The method for recycling waste lithium-ion secondary batteries according to claim 1, The method further comprises evaporating water in the aqueous lithium solution to recover lithium carbonate.

5. The method for recycling waste lithium-ion secondary batteries according to claim 1, The method further includes injecting a base into the aqueous lithium solution to increase the pH, and precipitating and recovering the lithium component as lithium hydroxide.

6. The method for recycling waste lithium-ion secondary batteries according to claim 1, The method further includes injecting the precipitate into an acidic aqueous solution to recover a metal aqueous solution in which a metal component contained in the precipitate is dissolved.

7. The method for recycling waste lithium-ion secondary batteries according to claim 1, The precipitate contains metallic nickel and cobalt.

8. The method for recycling waste lithium-ion secondary batteries according to claim 1, wherein the precipitate comprises metallic iron.

9. The method for recycling waste lithium-ion secondary batteries according to claim 1, In step (a), water is injected into the pyrolysis furnace.

10. The method for recycling waste lithium-ion secondary batteries according to claim 9, in, The injection amount of the water in step (a) is 1 to 10 parts by mass based on 100 parts by mass of the weight of the positive electrode material contained in the waste lithium ion secondary battery filled in the pyrolysis furnace.

11. The method for recycling waste lithium-ion secondary batteries according to claim 1, The waste lithium-ion secondary battery in step (a) is in an undischarged state.

12. The method for recycling waste lithium-ion secondary batteries according to claim 1, The waste lithium-ion secondary battery in step (a) is in an uncrushed state.

13. The method for recycling waste lithium-ion secondary batteries according to claim 1, The waste lithium ion secondary batteries in step (a) include waste lithium ion secondary batteries discarded as defects in the manufacturing process of lithium ion secondary batteries.

14. The method for recycling waste lithium-ion secondary batteries according to claim 1, The waste lithium ion secondary batteries in step (a) are decomposed and crushed and include waste lithium ion secondary batteries in a powder state.

15. The method for recycling waste lithium-ion secondary batteries according to claim 1, The internal temperature in step (b) is below 400°C.

16. The method for recycling waste lithium-ion secondary batteries according to claim 1, The pyrolysis furnace is not heated in step (c).

17. The method for recycling waste lithium-ion secondary batteries according to claim 1, Wherein step (c) lasts for 10 to 24 hours.

18. The method for recycling waste lithium-ion secondary batteries according to claim 1, Wherein step (c) is carried out in an inert gas atmosphere.

19. A metal powder recovered from waste lithium-ion secondary batteries, the powder being a precipitate recovered by the method for recycling waste lithium-ion secondary batteries according to claim 1, comprising metals Ni and Co and having magnetism.

20. The metal powder recovered from waste lithium-ion secondary batteries according to claim 19, The saturation magnetization value of the metal powder is greater than 15 emu / g.

21. The metal powder recovered from waste lithium-ion secondary batteries according to claim 19, The metal powder has an average particle size of 20 μm or less as measured by a particle size analyzer using laser diffraction, and a standard deviation in particle size distribution of 10 μm or less.

22. The metal powder recovered from waste lithium-ion secondary batteries according to claim 19, in, If the molar ratio of metal Ni to metal Co in the metal powder (M Ni / M Co , M Ni and M Co The molar ratio of Ni to Co in the positive electrode material of the waste lithium-ion secondary battery before pyrolysis is Ni / m Co , m Ni and m Co are the molar fraction of Ni and the molar fraction of Co in the positive electrode material, respectively) is a second molar ratio (M2), then the difference between the first molar ratio and the second molar ratio is less than 10% of the second molar ratio.

23. The metal powder recovered from waste lithium-ion secondary batteries according to claim 19, The metal powder does not contain metal ions other than Li, Ni, Co, Fe and Al, and does not contain F - and Cl - anion.

24. An iron powder recovered from a waste lithium ion secondary battery, the powder being a precipitate recovered from the method for recycling waste lithium ion secondary batteries according to claim 1 and comprising metallic iron or iron oxide.

25. A carbon powder recovered from a waste lithium ion secondary battery, the powder being a floating material separated and recovered from the method for recycling waste lithium ion secondary batteries according to claim 1, and comprising graphite, or graphite and silicon dioxide.

26. The carbon powder recovered from waste lithium-ion secondary batteries according to claim 25, The carbon powder has an average particle size of 20 μm or less as measured by a particle size analyzer using laser diffraction, and a standard deviation in particle size distribution of 10 μm or less.

27. A waste lithium ion secondary battery recycling powder, comprising lithium carbonate, metal nickel and metal cobalt as a first powder formed by the method for recycling waste lithium ion secondary batteries according to claim 1.

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