Method for recycling waste lithium-ion secondary battery and raw material for lithium-ion battery positive electrode material obtainable thereby

Abstract

To provide a method for recycling a waste lithium-ion secondary battery, the method being capable of recovering a raw material for a positive electrode material from a waste lithium-ion secondary battery in an economical and eco-friendly manner, and powder including a valuable component obtainable thereby.SOLUTION: A method for recycling a waste lithium-ion secondary battery according to the present invention includes the steps of: (a) loading an object to be heat-treated, which is at least a part of a waste lithium-ion secondary battery including a positive electrode material, into a heat-treatment furnace; (b) increasing the temperature inside the heat-treatment furnace to a range of 200-400°C; (c) maintaining the increased temperature; and (d) discharging first powder produced after the completion of the heat treatment of the waste lithium-ion secondary battery, the first powder including valuable metal powder containing a valuable metal component of the positive electrode material.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for recycling used lithium ion batteries and a powder containing valuable components obtained thereby, and more particularly to a recycling method for heat treating used lithium ion secondary batteries at low temperatures and a powder recovered thereby. [Background technology]

[0002] As the automotive industry shifts from internal combustion engine vehicles to electric vehicles, Europe and China, the growth centers of global electric vehicles and secondary batteries, are promoting the expansion of electric vehicles and securing their competitiveness through carbon dioxide regulations and eco-car roadmaps. As a result, rapid growth is expected in the global electric vehicle market.

[0003] Electric vehicle batteries are typically discarded after 5 to 10 years of use, so the waste battery market is expected to take off. The amount of waste electric vehicle batteries generated globally is expected to reach approximately 1.6 million tons by 2030, and many countries, particularly in Europe, are making large-scale investments in developing processes to recover valuable metals from waste batteries.

[0004] Unlike reuse, the waste battery recycling industry recovers valuable metals from waste batteries and recycles them as raw materials, which can simultaneously solve environmental problems and secure a stable supply of valuable resources.

[0005] Recycling of waste batteries generally involves discharging, dismantling, and crushing the batteries, followed by extracting valuable metals through hydrometallurgy or pyrometallurgy processes. However, pyrometallurgy, which is suitable for large-volume processing and has a high recovery rate, is attracting attention.

[0006] In dry smelting, the powder obtained by crushing is heated at high temperatures to burn off the organic compounds and polymer components contained in the crushed powder, and then the powder is crushed again and the valuable metals are extracted by wet processing using a strong acid.

[0007] Such a pyrometallurgical process requires a lot of time and equipment for discharge and pulverization, and subsequent complicated processes make it less economical. The product discharged after high temperature heating contains a large amount of impurities, which reduces the extraction rate of valuable components from the whole powder. Furthermore, since the product exists in agglomerated form, further pulverization and the use of strong acids are unavoidable in order to extract valuable components from it, which poses environmental problems. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention aims to provide a method for recycling used lithium ion secondary batteries, which is economical and environmentally friendly, and capable of recovering raw materials for positive electrode materials from used lithium ion secondary batteries, and a powder containing valuable components obtained therefrom. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the method for recycling used lithium ion secondary batteries according to the present invention includes the steps of: (a) loading a heat treatment object, which is at least a part of a used lithium ion secondary battery including a cathode material, into a heat treatment furnace; (b) increasing the internal temperature of the heat treatment furnace to a range of 200 to 400°C; (c) maintaining the increased temperature; and (d) discharging a first powder produced after the heat treatment of the used lithium ion secondary batteries is completed, wherein the first powder contains valuable metal powder containing a valuable metal component of the cathode material.

[0010] In the method for recycling used lithium ion secondary batteries according to the present invention, the first powder may contain no organic components and may have a fluorine content of 2% by weight or less.

[0011] In the method for recycling used lithium ion secondary batteries according to the present invention, the first powder may be free of organic components and fluorine.

[0012] In the recycling method for used lithium ion secondary batteries according to the present invention, the valuable metal powder may contain Ni and Co, or Fe.

[0013] In addition, in the recycling method for used lithium ion secondary batteries according to an embodiment of the present invention, the valuable metal powder may include reduced Ni and Co.

[0014] In addition, the recycling method for used lithium ion secondary batteries according to the present invention may be characterized in that in the steps (b) and (c), gas generated from inside the heat treatment furnace is forcibly exhausted.

[0015] In addition, the recycling method for used lithium ion secondary batteries according to the present invention may be characterized in that in steps (b) and (c), the inside of the heat treatment furnace is made into a negative pressure state to forcibly exhaust the gas.

[0016] In addition, in the recycling method for used lithium ion secondary batteries according to the present invention, in steps (b) and (c), the gas may be forcibly exhausted through a fan disposed in the heat treatment furnace.

[0017] In addition, the recycling method for used lithium ion secondary batteries according to the present invention is characterized in that the forced exhaust through the fan is performed intermittently.

[0018] In the recycling method for used lithium ion secondary batteries according to an embodiment of the present invention, in step (a), the object to be heat-treated may be a positive electrode recovered by disassembling the used lithium ion batteries.

[0019] Meanwhile, the present invention can provide valuable metal powder for a cathode material recovered through the above-mentioned recycling method for used lithium ion secondary batteries. [Effects of the Invention]

[0020] The recycling method for used lithium ion secondary batteries according to the present invention is economical and environmentally friendly, so that it can increase the recycling rate of used lithium ion secondary batteries and solve environmental problems that may occur during recycling.

[0021] Furthermore, the valuable metal powder for cathode material obtained by the present invention makes it possible to manufacture highly economical lithium ion secondary batteries. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 shows the X-ray diffraction pattern of valuable metal powder recovered according to one embodiment of the present invention.

[0023] [Figure 2] FIG. 2 shows the results of Raman spectrum analysis of valuable metal powder recovered by one embodiment of the present invention.

[0024] [Figure 3] FIG. 3 shows the results of XRF (X-ray fluorescence) analysis of valuable metal powder recovered by one embodiment of the present invention.

[0025] [Figure 4] FIG. 4 shows an image of valuable metal powder recovered by processing according to the comparative example and the results of XRF analysis. DETAILED DESCRIPTION OF THE INVENTION

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The present invention will now be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily understand the present invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0027] Throughout this specification, unless specifically stated to the contrary, the term "comprising" a part means that it may further include other elements, rather than excluding other elements.

[0028] As used herein, terms of degree such as "about," "substantially," and the like are used in the sense of a numerical value or close to a numerical value when manufacturing and material tolerances inherent in the referred meaning are given, and are used to facilitate understanding of the present application and to prevent unscrupulous infringers from unfairly exploiting the disclosure in which precise or absolute numerical values ​​are referred to. Furthermore, throughout the present specification, "the step of" or "the step of" does not mean "the step for."

[0029] Throughout this specification, the term "combinations thereof" contained in a Markush expression means a mixture or combination of one or more elements selected from the group of elements set forth in the Markush expression, and means including one or more elements selected from the group of elements.

[0030] Throughout this specification, the phrase "A and / or B" means "A or B, or A and B."

[0031] A method for recycling used lithium ion secondary batteries according to one aspect of the present invention includes the steps of: (a) loading a heat treatment object, which is at least a part of a used lithium ion secondary battery including a cathode material, into a heat treatment furnace; (b) increasing the internal temperature of the heat treatment furnace to a range of 200 to 400°C; (c) maintaining the increased temperature; and (d) discharging a first powder produced after the heat treatment of the used lithium ion secondary batteries is completed, wherein the first powder contains valuable metal powder containing a valuable metal component of the cathode material.

[0032] The waste lithium-ion secondary batteries to be recycled in this invention are those that use lithium iron phosphate or a ternary oxide containing nickel and cobalt as a cathode material. The waste lithium-ion secondary batteries fed into the heat treatment furnace may be entire waste lithium-ion secondary battery cells, or at least a portion of the cells containing a ternary oxide cathode material or a cathode material containing lithium iron phosphate. The waste lithium-ion secondary batteries may also be black mass, which is a powder produced by disassembling and crushing waste lithium-ion secondary batteries, or waste lithium-ion secondary batteries that are discarded due to defects during the manufacturing process.

[0033] In addition, in one embodiment of the present invention, in order to effectively recover valuable components of the cathode material, the used lithium ion secondary battery may be disassembled to separate only the cathode, which is a composite of the current collector and the cathode material, and then the separated cathode may be placed inside a heat treatment furnace.

[0034] The conventional recycling process for used lithium-ion secondary batteries involves disassembling the batteries, pyrolyzing them at high temperatures to form agglomerates, and then pulverizing them. As a result, the cathode and cathode materials to be recovered, as well as the case and current collector, are crushed into agglomerates containing many impurities, resulting in significant deformation of the cathode and cathode materials, which are not maintained in their raw state.

[0035] In contrast, the recycling method of the present invention removes the electrolyte through low-temperature heat treatment, decomposes the binder contained in the waste lithium-ion batteries, and recovers valuable metal powder for cathode material with high purity, which can be used as a raw material for cathode material by containing the valuable metal components contained in the cathode material.

[0036] The valuable metal powder for cathode material thus separated can be recycled for the production of lithium-ion batteries after simple post-processing.

[0037] In the above-described recycling method, the heat treatment process may be carried out at a temperature in the range of 200 to 400°C, preferably 200 to 350°C, or 250 to 350°C. By heating the battery at a relatively low temperature, the binder, electrolyte, and other components contained in the battery are thermally decomposed and removed. In particular, the internal binder, electrolyte, and other components may generate heat and undergo thermal decomposition. Compared to conventional recycling methods, the heat treatment is carried out at a low temperature, which can reduce energy costs. Furthermore, the low-temperature heat treatment can facilitate the recovery of valuable metal components contained in the cathode material, and Ni, Co, or Fe can be easily recovered with high purity.

[0038] In particular, Ni and Co can be recovered in a reduced metallic state through low-temperature pyrolysis. By recovering them in a metallic state rather than an oxide state, they can be more economically converted into precursors, which are raw materials for producing cathode materials.

[0039] Meanwhile, in the above-mentioned steps (b) and (c), it is preferable to forcibly exhaust gases generated from inside the heat treatment furnace.

[0040] The key to discharging these gases is that the gases generated by the decomposition of binders, electrolytes, etc. during heat treatment contain fluorine. If these fluorine-containing gases remain in the heat treatment furnace, they will combine with the cathode material, cathode material, etc. to form strongly bonded agglomerates. If the heat-treated powders combine to form agglomerates, they will be difficult to pulverize through post-treatment processes. Therefore, rapid discharge of fluorine-containing gases is an important issue. However, conventional high-temperature heat treatment inevitably produces a rapid generation of fluorine-containing gases, which causes the gases to remain in the heat treatment furnace for a long time, accelerating the agglomeration of the powder.

[0041] In contrast, the method for recycling used lithium ion secondary batteries according to the present invention is carried out by controlling the decomposition rate of binders and the like through low-temperature heat treatment, thereby suppressing the rapid generation of fluorine component gas and keeping the amount of generated gas at an appropriate level, and at the same time, by quickly and forcibly discharging the generated gas, the time that the fluorine component-containing gas remains in the heat treatment furnace can be minimized, thereby preventing the agglomeration of powder due to fluorine.

[0042] Due to the forced exhaust during the heat treatment process, a negative pressure state may be maintained inside the heat treatment furnace, and gases generated when the binder, electrolyte, separator, etc. are decomposed as the waste lithium ion secondary batteries are heated in the heat treatment furnace can be discharged to the outside by maintaining this negative pressure state. To maintain this negative pressure state, the heat treatment furnace may have a gas exhaust port and a pump for maintaining the negative pressure may be connected to the exhaust port.

[0043] In addition, exhausting the atmosphere inside the heat treatment furnace can be performed using a fan disposed in the heat treatment furnace. The decomposition gas generated inside the heat treatment furnace can be continuously or intermittently exhausted through the fan. If the exhaust rate of the internal atmosphere is too high, it may be difficult to increase and maintain the temperature inside the heat treatment furnace, so exhausting the internal atmosphere may be performed intermittently in conjunction with the internal temperature.

[0044] The first powder recovered after heat treatment in this recycling method for used lithium ion secondary batteries may be free of organic components and fluorine. Impurities such as binders are completely removed through low-temperature heat treatment and forced evacuation, resulting in the absence of organic components and fluorine. The heat-treated used lithium ion secondary batteries can be easily recovered in powder form and used for manufacturing lithium ion secondary batteries. Here, "free of fluorine" means that fluorine is not detectable in analysis using X-ray fluorescence analysis.

[0045] On the other hand, the first powder described above does not contain any organic components and may contain fluorine at a concentration of 2% by weight or less. Even if a small amount of fluorine is contained, once it is below a certain level, it can be recovered in powder form without the powder agglomerating.

[0046] As described above, the method for recycling used lithium ion secondary batteries according to the present invention can recover valuable components contained in the cathode material in a powder state by heat-treating the used lithium ion secondary batteries at a low temperature and simultaneously discharging gas generated during the heat treatment, thereby eliminating the need for an additional pulverization process, and the recovered valuable metal powder containing the cathode material components can be recycled for manufacturing new batteries.

[0047] <Example>

[0048] A used lithium ion secondary battery using an NCM cathode material was treated by the recycling method according to the present invention, and the first powder was collected.

[0049] After loading the waste lithium-ion secondary batteries into a heat treatment furnace, the waste lithium-ion secondary batteries were heat-treated while adjusting the internal temperature of the heat treatment furnace to 250°C. The internal temperature was increased at a rate of 1°C / min and maintained at the increased temperature for 12 hours. During the reaction, the internal atmosphere was vented using a fan, and the internal temperature was maintained within the range of 250±15°C in conjunction with a temperature sensor. After the reaction was completed, the powdered material was separated and collected to obtain a first powder.

[0050] The obtained first powder was added to water and subjected to ultrasonic treatment. The treated solution was left for a certain period of time to separate into precipitate and suspended matter. The precipitate was then collected and dried to recover the valuable metal powder.

[0051] Figure 1 shows the results of X-ray diffraction analysis of the resulting first powder. Peaks for reduced metallic Ni and Co are observed, along with diffraction peaks for Mn oxide and crystalline carbon. This indicates that Ni and Co, which are valuable components of NCM, can be recovered as metallic components. Powder recovered in this metallic state allows for the production of a precursor for a cathode material in a more economical and environmentally friendly manner than further processing oxide powders.

[0052] Figure 2 shows the Raman spectrum analysis results for Powder 1. No other organic-related peaks were observed in the powder other than NCM components and carbon, indicating that the organic matter had been completely removed.

[0053] FIG. 3 shows the results of XRF component analysis of the first powder, and it can be seen that no hydrofluoric acid was detected.

[0054] On the other hand, Figure 4 shows the powder recovered after heat treatment of commercial black mass at low temperature, but without evacuation. The powder recovered in this way was hard and agglomerated, making it difficult to pulverize, and a large amount of fluorine was detected.

Claims

1. (a) charging a heat treatment object, which is at least a part of a waste lithium ion secondary battery including a cathode material, into a heat treatment furnace; (b) increasing the internal temperature of the heat treatment furnace to a range of 200 to 400°C; (c) maintaining the elevated temperature to heat-treat the object; and (d) discharging a first powder produced after the heat treatment of the waste lithium ion secondary batteries is completed; The method for recycling used lithium ion secondary batteries, wherein the first powder contains valuable metal powder containing a valuable metal component of the positive electrode material.

2. 2. The method for recycling used lithium ion secondary batteries according to claim 1, wherein the first powder does not contain any organic component and has a fluorine content of 2% by weight or less.

3. The method for recycling used lithium ion secondary batteries according to claim 1 , wherein the first powder does not contain organic components and fluorine.

4. 2. The method for recycling used lithium ion secondary batteries according to claim 1, wherein the valuable metal powder contains Ni and Co or Fe.

5. 2. The method for recycling used lithium ion secondary batteries according to claim 1, wherein the valuable metal powder contains reduced Ni and Co.

6. 2. The method of claim 1, wherein gas generated from the heat treatment furnace is forcibly exhausted in steps (b) and (c).

7. 7. The method of claim 6, wherein in steps (b) and (c), the inside of the heat treatment furnace is made to be in a negative pressure state to forcibly exhaust the gas.

8. 7. The method of claim 6, wherein in steps (b) and (c), the gas is forcibly exhausted through a fan disposed in the heat treatment furnace.

9. 9. The method for recycling used lithium ion secondary batteries according to claim 8, wherein the forced exhaust through the fan is performed intermittently.

10. 2. The method of claim 1, wherein in step (a), the object to be heat-treated is a positive electrode recovered by disassembling the used lithium ion battery.

11. A valuable metal powder for a positive electrode material, recovered through the recycling method for used lithium ion secondary batteries according to any one of claims 1 to 10.

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