Lithium recovery method

Abstract

The present invention relates to a lithium recovery method and, more specifically, to a lithium recovery method comprising the steps of: obtaining a leachate in which a lithium component is dissolved from positive electrode material powder; and purifying the lithium component by introducing the leachate into a flow-capacitive deionization device. According to the present invention, it is possible to provide a lithium recovery method that is eco-friendly by enabling high-purity lithium to be recovered and wastewater generation to be reduced by easily removing impurities through electrochemical adsorption and desorption processes from the leachate in which the lithium component is dissolved from the positive electrode material powder. In addition, since the purification and filtration of lithium are simultaneously performed, the process is simpler compared to the prior art and a continuous process is possible, thereby providing the method with reduced process costs and energy.

Description

Lithium recovery method

[0001] [Cross-reference with application(s)]

[0002] The present application claims the benefit of priority based on Korean Patent Application No. 10-2024-0131492 filed on September 27, 2024, and Korean Patent Application No. 10-2025-0138761 filed on September 25, 2025, based thereon, and all contents disclosed in the documents of said Korean patent applications are incorporated as part of this specification.

[0003] The present invention relates to a method for recovering lithium, and more specifically, to a method for recovering lithium of high purity by easily removing impurities, particularly anionic impurities, through an electrochemical adsorption and desorption process of a leachate in which lithium components are selectively dissolved from waste cathode material powder, and furthermore, being environmentally friendly by reducing the amount of wastewater generated, and also reducing process costs and energy by simultaneously performing the purification and filtration of lithium, thereby making the process simpler and enabling a continuous process compared to existing processes.

[0004] The demand for lithium-ion batteries has continuously increased since the 1990s alongside the portable electronic device market, and has surged even more globally recently due to the rapid expansion of the electric vehicle market. This could lead to instability in the supply and demand of lithium resources in the near future, and the continuously accumulating end-of-life waste batteries could also cause significant environmental problems. To address these issues, the recycling of waste batteries is a critical technical challenge.

[0005] A lithium-ion battery is largely composed of a positive electrode in which a positive active material layer is coated on a metal foil such as aluminum, a negative electrode in which a negative active material layer is coated on a metal foil such as copper, a separator that prevents the positive and negative electrodes from mixing with each other, and an electrolyte that enables the movement of lithium ions between the positive and negative electrodes.

[0006] The cathode accounts for more than 60% of the cost of a lithium-ion battery. For this cathode, lithium cobalt oxide (LiCoO2), which has excellent reversibility, a low self-discharge rate, high capacity, and high energy density, and is easy to synthesize, is used. Alternatively, to reduce the use of expensive cobalt, lithium composite oxides such as lithium nickel cobalt manganese oxide (LiNiMnCoO2), lithium manganese oxide (LiMnO2), or lithium iron phosphate (LiFePO4) containing Ni and Mn are used. Since the above cathode materials contain about 5 to 7% lithium, methods for recovering lithium from the cathode materials of spent lithium-ion batteries are receiving significant attention.

[0007] Conventional methods for recovering lithium from lithium-ion battery cathode materials employ a terminal recovery approach in which the entire cathode material is leached using acid, additives for recovering valuable metals are introduced, and the lithium components contained in the remaining solution are recovered. This terminal lithium recovery technology contains a large amount of impurities accumulated during the process, requiring repeated additional purification steps to obtain high-purity lithium. Furthermore, it uses high-concentration acid solvents to leach lithium components containing valuable metals, generates a large amount of wastewater due to the repetitive process, and suffers from problems such as low purity and recovery rates of the recovered lithium.

[0008] Therefore, there is a need to develop a lithium recovery method that can recover lithium from spent lithium-ion battery cathode materials with high purity, reduce wastewater generation, and save energy, cost, and time required for lithium filtration.

[0009] [Prior Art Literature]

[0010] [Patent Literature]

[0011] Korean Patent Publication No. 2012-0031832

[0012] In order to solve the problems of the conventional technology described above, the present invention aims to provide a method for recovering lithium that is environmentally friendly by easily removing impurities, particularly anionic impurities, through an electrochemical adsorption and desorption process of a leachate in which lithium components are selectively dissolved from waste cathode material powder, thereby reducing the amount of wastewater generated, and also reduces process costs and energy by simplifying the process and enabling a continuous process compared to existing processes by simultaneously performing lithium purification and filtration.

[0013] The above and other objectives of the present invention can all be achieved by the present invention described below.

[0014] To achieve the above objective, the present invention provides a method for recovering lithium, characterized by comprising the steps of: obtaining a leaching solution in which a lithium component is dissolved from a cathode material powder; and introducing the leaching solution into a flow capacitive deionization device to purify the lithium component.

[0015] In addition, II) the present invention provides a method for recovering lithium, characterized by comprising the steps of: passing a leaching solution in which a lithium component is dissolved between an anion adsorption unit including a negative film flow electrode and a cation adsorption unit including a positive film flow electrode to adsorb lithium cations onto the positive film flow electrode; passing the positive film flow electrode on which lithium cations are adsorbed between a current collector and a cation exchange membrane to desorb lithium cations from the positive film flow electrode; and collecting the desorbed lithium cations as deionized water.

[0016] In addition, III) the present invention provides a method for recovering lithium, characterized by comprising: (a) a step of crushing and / or grinding a lithium-ion battery positive electrode to obtain a positive electrode material powder; (b) a step of adding a leaching solvent to the positive electrode material powder to obtain a leaching solution in which a lithium component is dissolved; (c) a step of purifying the lithium component from the leaching solution through a flow capacitive deionization device; and (d) a step of obtaining the purified lithium component as a lithium crystalline salt.

[0017] IV) In the above I) to III), in step (a), the anode material powder is preferably heat-treated with a carbon-containing reducing agent to obtain a heat-treated product, and the obtained heat-treated product may be crushed and / or ground and fed into step (b).

[0018] V) In the above I) to IV), the heat treatment can preferably be carried out at a temperature of 550 to 750 ℃ ​​under a reducing gas or an inert gas.

[0019] VI) In I) to V) above, the carbon-containing reducing agent can preferably be used in an amount of 0.3 to 3 moles per mole of the positive active material in the positive material powder.

[0020] VII) In the above I) to VI), the carbon-containing reducing agent may preferably be an organic material containing carbon, an inorganic material containing carbon, a carbon-based cathode material, or a mixture of two or more of these.

[0021] VIII) In the above I) to VII), the above step (b) preferably involves leaching the cathode material powder obtained in step (a) with water to obtain a leaching solution in which lithium is dissolved and a leaching residue, and separating them to obtain the leaching solution.

[0022] IX) In the above I) to VIII), the above step (b) preferably involves adding the cathode material powder obtained in step (a) to a mixture of an acidic solution and an oxidizing agent to obtain a leaching solution in which lithium is dissolved and a leaching residue, and separating them to collect the leaching solution.

[0023] X) In the above I) to IX), the acidic solution in step (b) may preferably have an acid concentration of 0.1 to 1.5 molar concentration (mol / L).

[0024] XI) In the above I) to X), in step (b), the acidic solution may preferably be added in an amount of 0.5 to 1.5 moles of acid per 1 mole of positive active material in the positive material powder.

[0025] XII) In the above I) to XI), in step (b), the oxidizing agent may preferably be added in an amount of 0.5 to 2.3 moles per mole of the anode active material in the anode powder.

[0026] XIII) In the above I) to XII), the oxidizing agent in step (b) may preferably include one or more selected from the group consisting of hydrogen peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, oxygen, and air.

[0027] XIV) In the above I) to XIII), the leaching solution obtained in step (b) can preferably be introduced into step (c) after performing the impurity removal step (b').

[0028] XV) In the above I) to XIV), the impurity removal step (b') may preferably be a step of filtering the leachate with a nanofiltration membrane.

[0029] XVI) In the above I) to XV), the impurity removal step (b') may preferably be a step of adding one or more impurity removal agents selected from the group consisting of lithium hydroxide (LiOH); a basic compound; a cathode material powder; and the filtrate remaining after obtaining a lithium crystal salt from a purified lithium component to the leaching solution.

[0030] XVII) In the above I) to XVI), the step of purifying lithium in step (c) can preferably be filtered together with the purification.

[0031] XVIII) In the above I) to XVII), the leaching solution introduced into the flow capacitive deionization device in step (c) may preferably have a total of 1 weight% or less of metal components excluding lithium.

[0032] XIX) In the above I) to XVIII), in step (c), the flow capacitive deionization device may preferably include: a lithium leaching solution circulation tank; an anion adsorption unit comprising a negative film flow electrode circulation tank, a current collector, and an anion exchange membrane; a cation adsorption unit comprising a cation exchange membrane, a current collector, and a positive film flow electrode circulation tank; a cation desorption unit comprising a current collector and a cation exchange membrane; and a cation collection unit comprising a deionized water circulation tank, an anion exchange membrane, a current collector, and a negative film flow electrode circulation tank.

[0033] XX) In the above I) to XIX), the flow capacitive deionization device may preferably include the step of passing a leaching solution in which a lithium component is dissolved between an anion adsorption part including a negative film flow electrode and a cation adsorption part including a positive film flow electrode to adsorb lithium cations onto the positive film flow electrode; the step of passing the positive film flow electrode on which lithium cations are adsorbed between a current collector and a cation exchange membrane to desorb lithium cations from the positive film flow electrode; and the step of collecting the desorbed lithium cations as deionized water.

[0034] XXI) In the above I) to XX), the flow capacitive deionization device may further include: a step of passing a leaching solution in which a lithium component is dissolved between a cation adsorption part including a positive film flow electrode and an anion adsorption part including a negative film flow electrode to adsorb anions onto the negative film flow electrode; a step of passing the negative film flow electrode on which anions are adsorbed between a current collector and an anion exchange membrane to desorb anions from the negative film flow electrode; and a step of collecting the desorbed anions as deionized water.

[0035] XXII) In I) to XXI) above, the positive and negative flow electrodes may preferably each comprise an active material, a conductive additive, and a solvent.

[0036] XXIII) In the above I) to XXII), the active material may preferably be one or more selected from the group consisting of activated carbon, carbon beads, mesoporous carbon, carbon nanotubes, graphene, carbon black, activated carbon fiber, and MnO2.

[0037] XXIV) In the above I) to XXIII), the conductive additive may preferably be one or more selected from the group consisting of carbon black, carbon nanotubes, graphene, and reduced graphene oxide (rGO), and may not be the same as the active material.

[0038] XXV) In I) to XXIV) above, the solvent may preferably be a sodium chloride (NaCl) solution, deionized water, or distilled water.

[0039] XXVI) In the above I) to XXV), the lithium crystalline salt obtained in step (d) may preferably comprise one or more selected from the group consisting of LiOH, Li2CO3, LiCl, Li2SO4, and LiNO3.

[0040] XXVII) In the above I) to XXVI), the above step (d) may preferably be a step of carbonating the purified lithium component to obtain lithium carbonate.

[0041] XXVIII) In the above I) to XXVII), the lithium crystal salt obtained in step (d) may preferably have a lithium purity of 99 weight% or more.

[0042] XXIX) In the above I) to XXVIII), the remaining liquid after obtaining the lithium component purified in step (d) as a lithium crystal salt can preferably be introduced into a flow capacitive deionization device and reused.

[0043] XXX) In the above I) to XXIX), the cathode material may preferably comprise one or more selected from the group consisting of lithium cobalt oxide; lithium manganese oxide; lithium iron phosphate compound; lithium nickel cobalt aluminum oxide; lithium nickel oxide; a nickel manganese-based lithium composite metal oxide in which a portion of the nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn); and an NCM-based lithium composite transition metal oxide in which a portion of the nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn) and cobalt (Co).

[0044] XXXI) In the above I) to XXX), the lithium-ion battery positive electrode may preferably be the positive electrode of a spent lithium-ion battery.

[0045] In addition, the present invention provides a lithium recovery device comprising: a lithium leaching solution circulation tank; an anion adsorption unit including a negative film flow electrode circulation tank, a current collector, and an anion exchange membrane; a cation adsorption unit including a cation exchange membrane, a current collector, and an positive film flow electrode circulation tank; a cation desorption unit including a current collector and a cation exchange membrane; and a cation collection unit including a deionized water circulation tank, an anion exchange membrane, a current collector, and a negative film flow electrode circulation tank; wherein the lithium cations contained in the lithium leaching solution move to the positive film flow electrode circulation tank via the cation exchange membrane of the adsorption unit, and then are collected in the deionized water circulation tank of the collection unit via the cation exchange membrane of the desorption unit.

[0046] According to the present invention, by purifying the leaching solution in which lithium components are dissolved from waste cathode material powder through a flow capacitive deionization device, which is an electrochemical adsorption and desorption process, the removal of impurities, particularly anionic impurities, is excellent, thereby recovering lithium with high purity. Furthermore, the lithium recovery rate is maximized by recirculating the remaining liquid after obtaining the purified lithium components as lithium crystal salts, and the process is simplified, a continuous process is possible, energy can be saved, and the amount of wastewater generated can be reduced, thereby providing an environmentally friendly method for recovering lithium.

[0047] In addition, the recovered lithium according to the present invention has the effect of having a purity of 99 weight% or more.

[0048] The following drawings attached to this specification illustrate embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention in conjunction with the detailed description provided below; therefore, the present invention should not be interpreted as being limited to the matters described in these drawings.

[0049] FIG. 1 is a process diagram for a method of recovering lithium from waste lithium-ion battery cathode material powder according to one embodiment of the present invention.

[0050] FIG. 2 is a process diagram for a method of recovering lithium from waste lithium-ion battery cathode material powder according to Example 1 of the present invention.

[0051] FIG. 3 is a process diagram for a method of recovering lithium from waste lithium-ion battery cathode material powder according to Example 2 of the present invention.

[0052] Figure 4 is a process diagram for a method of recovering lithium from waste lithium-ion battery cathode material powder according to Example 3 of the present invention.

[0053] FIG. 5 is a process diagram for a method of recovering lithium from waste lithium-ion battery cathode material powder according to one embodiment of the present invention.

[0054] FIG. 6 is a process diagram for a method of recovering lithium from waste lithium-ion battery cathode material powder according to one embodiment of the present invention.

[0055] FIG. 7 is a schematic diagram illustrating a process for purifying a lithium component by introducing a leaching solution in which a lithium component is dissolved into a flow capacitive deionization (FCDI) device comprising an anion adsorption unit, a cation adsorption unit, a cation desorption unit, and a cation collection unit, according to one embodiment of the present invention.

[0056] FIG. 8 is a schematic diagram illustrating a process according to one embodiment of the present invention in which a leaching solution in which a lithium component is dissolved is introduced into a flow capacitive deionization unit comprising one module including an anion adsorption unit and a cation adsorption unit to adsorb lithium cations onto a positive membrane flow electrode, and then the cation adsorption unit is used as a cation desorption unit and the anion adsorption unit is used as a cation collection unit to desorb and recover lithium from the positive membrane flow electrode on which lithium cations are adsorbed.

[0057] FIG. 9 is a schematic diagram illustrating a process in which an adsorption negative film flow electrode regeneration unit is added to a process for purifying a lithium component by introducing a leaching solution in which a lithium component is dissolved into a flow capacitive deionization device comprising an anion adsorption unit, a cation adsorption unit, a cation desorption unit, and a cation collection unit, as one embodiment according to the present invention.

[0058] Figure 10 is a photograph taken of the Li2CO3 powder obtained from Example 1 placed in a transparent container.

[0059] Figure 11 is a graph of XRD analysis of Li2CO3 obtained in Example 1.

[0060] Figure 12 is a graph of XRD analysis of Li2CO3 obtained in Comparative Example 1.

[0061] While researching a method to recover lithium with high purity from lithium-ion battery cathode materials, the inventors obtained a leachate containing dissolved lithium components from waste cathode material powder and confirmed that when lithium is recovered from said leachate through a predetermined flow-capacitive deionization device, the purity and recovery rate of lithium are significantly improved, the process is simplified, and a continuous process is possible, thereby enhancing efficiency. Based on this, they devoted themselves to further research and completed the present invention.

[0062] The method for recovering lithium described herein will be explained in detail below.

[0063] However, terms and words used in this specification and claims cannot be interpreted as being limited to their ordinary or dictionary meanings, and must be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor may appropriately define the concept of the terms to best describe his application. Accordingly, it should be understood that the embodiments described in this specification and the configurations illustrated in the drawings are merely one embodiment of the invention and do not represent all of the technical spirit of the invention, and that there may be various equivalents and modifications that can replace them, and that they may be arranged, replaced, combined, separated, or designed into various other configurations.

[0064] All technical and scientific terms used in this description have the same meaning as commonly understood by those skilled in the art to which the present invention belongs, unless otherwise defined.

[0065] Lithium recovery method

[0066] The lithium recovery method of the present invention is characterized by comprising the steps of obtaining a leaching solution in which a lithium component is dissolved from a cathode material powder, and introducing the leaching solution into a flow capacitive deionization device to purify the lithium component. In this case, purification through a flow capacitive deionization device, which is an electrochemical adsorption and desorption process, effectively removes impurities, particularly anionic impurities, thereby recovering lithium with high purity. Furthermore, the lithium recovery rate is maximized by recirculating the remaining liquid or lithium-containing waste liquid after obtaining the purified lithium component as a lithium crystal salt. Additionally, the process is simplified, energy is saved, and the amount of wastewater generated can be reduced, thus providing environmentally friendly advantages.

[0067] In addition, the lithium recovery method of the present invention is characterized by comprising the steps of: passing a leaching solution in which a lithium component is dissolved between an anion adsorption unit including a negative film flow electrode and a cation adsorption unit including a positive film flow electrode to adsorb lithium cations onto the positive film flow electrode; passing the positive film flow electrode on which lithium cations are adsorbed between a current collector and a cation exchange membrane to desorb lithium cations from the positive film flow electrode; and collecting the desorbed lithium cations as deionized water. In this case, the removal of impurities, particularly anion impurities, is excellent through a flow capacitive deionization device, which is an electrochemical adsorption and desorption process, thereby recovering lithium with high purity. Furthermore, the lithium recovery rate is maximized by recirculating the remaining filtrate or lithium-containing waste liquid after obtaining the purified lithium component as a lithium crystal salt. Additionally, the process is simplified, energy is saved, and the amount of wastewater generated can be reduced, thus providing environmentally friendly advantages.

[0068] In addition, the lithium recovery method of the present invention is characterized by comprising: (a) a step of obtaining a cathode material powder by crushing and / or grinding a lithium-ion battery cathode; (b) a step of obtaining a leaching solution in which a lithium component is dissolved from the cathode material powder; (c) a step of purifying the lithium component through a flow capacitive deionization device; and (d) a step of obtaining the purified lithium component as a lithium crystalline salt. In this case, by purifying through a flow capacitive deionization device, which is an electrochemical adsorption and desorption process, the removal of impurities, particularly anionic impurities, is excellent, thereby recovering lithium with high purity. Furthermore, the lithium recovery rate is maximized through the recirculation of the remaining liquid or lithium-containing waste liquid after obtaining the purified lithium component as a lithium crystalline salt. Additionally, the process is simplified, energy is saved, and the amount of wastewater generated can be reduced, thus providing an environmentally friendly advantage.

[0069]

[0070] The lithium recovery method is explained in detail below, divided into steps.

[0071]

[0072] (a) A step of obtaining cathode material powder by crushing and / or grinding the lithium-ion battery cathode.

[0073] The lithium recovery method of the present invention comprises the step of (a) crushing and / or grinding a lithium-ion battery positive electrode to obtain a positive electrode material powder. In this case, the positive electrode active material layer and the current collector are easily separated from a waste positive electrode in which a positive electrode active material layer comprising a positive electrode active material and a conductive material is bonded to a current collector by a binder, thereby allowing the positive electrode active material layer to be obtained as a powder, and there is an advantage that the lithium component is easily dissolved in a subsequent process.

[0074]

[0075] The cathode material described herein means that it includes a cathode active material or is a cathode active material, and may include, for example, a cathode active material, a conductive material, a binder, and aluminum incorporated during the crushing and / or grinding process.

[0076]

[0077] The positive electrode of the above-mentioned waste lithium-ion battery may be, for example, a discarded lithium-ion battery positive electrode, a defective product generated during the positive electrode coating process, or a positive electrode scrap discarded after cutting the electrode plate; preferably, it may be a discarded lithium-ion battery positive electrode, and in this case, there is an economic advantage of recycling resources by recovering expensive lithium.

[0078]

[0079] The above crushing may, for example, involve cutting or shredding discarded lithium-ion battery positive electrodes, and preferably may be performed using dry crushing equipment, specifically using a hand mill, pin mill, disc mill, cutting mill, hammer mill, or shredder.

[0080]

[0081] The crushed anode can be ground using, for example, a mixer, a hand mill, a pin mill, a disc mill, a cutting mill, or a hammer mill, and preferably by a mixer; in this case, there is an advantage that the current collector pieces are finely cut and the anode material is separated from the current collector pieces.

[0082]

[0083] The above-mentioned crushed anode material can be obtained as a powder, for example, through sieving, and in this case, leaching is facilitated more easily.

[0084] The above sieve can be sieved, for example, with a mesh of 30 to 500, preferably 32 to 400, and more preferably 35 to 325. In this case, the current collector pieces separated during the crushing and / or grinding process are separated, and the size of the crushed and / or ground positive active material layer is homogenized, which has the advantage of allowing the lithium component to be easily dissolved in a subsequent process.

[0085]

[0086] In addition, the above-mentioned cathode material powder is not particularly limited if it is manufactured using a method of producing cathode material powder from waste lithium-ion battery cathodes commonly practiced in the technical field to which the present invention belongs, and it may be commercially purchased and used as long as it conforms to the definition of cathode material powder according to the present invention.

[0087]

[0088] The cathode material powder obtained in step (a) above may be heat-treated with, for example (a'), a carbon-containing reducing agent to obtain a heat-treated product, and the process may further include a step of crushing the obtained heat-treated product, and the crushed heat-treated product may be fed into step (b). In this case, by removing the binder and conductive material from the cathode material powder obtained from the waste cathode through heat treatment, there is an advantage that the lithium component is easily dissolved in the subsequent process.

[0089] The above heat treatment can be carried out, for example, under a reducing gas or an inert gas, and preferably under a nitrogen (N2) gas atmosphere. In this case, the cathode material powder is easily reduced, which has the advantage of recovering high-purity lithium in a high yield.

[0090] The flow rate of the above reducing gas or inert gas can be, for example, 1 to 20 L / min, preferably 3 to 17 L / min, more preferably 5 to 15 L / min, and within this range, there is an advantage of excellent reaction efficiency.

[0091]

[0092] The above heat treatment can be performed, for example, at 550 to 750 ℃, preferably at 570 to 730 ℃, more preferably at 600 to 700 ℃, and even more preferably at 600 to 670 ℃. Within this range, the lithium of the cathode material is converted to a high level of lithium compound, and there is an advantage of reducing process costs.

[0093] After the above heat treatment, furnace cooling can be performed.

[0094] In this description, furnace cooling refers to the operation of cooling a heat-treated material inside a furnace, specifically a method of slowly cooling from a high temperature inside the furnace.

[0095]

[0096] The rate of temperature increase until reaching the above heat treatment temperature may be, for example, 1 to 20 ℃ / min, preferably 1 to 10 ℃ / min, more preferably 1 to 7 ℃ / min, and even more preferably 1 to 5 ℃ / min. Within this range, it is possible to implement it without putting strain on the heat treatment equipment, and there is an advantage of not causing thermal shock to the cathode material.

[0097]

[0098] The above heat treatment can be carried out for, for example, 0.5 to 7 hours, preferably 1.5 to 6.5 hours, more preferably 2.5 to 6 hours, and even more preferably 3.5 to 5.5 hours, and within this range, the binder and conductive material in the cathode material are removed and the lithium is converted to a lithium compound by carbon to a high level, which has the advantage.

[0099] The above heat treatment step may, for example, not include a reducing agent other than a carbon-containing reducing agent, and in this case, there is an advantage of reducing impurities and increasing the purity and recovery rate of the recovered lithium compound.

[0100] In this description, the heat treatment time refers to the time processed at the corresponding heat treatment temperature, and the time to reach the corresponding heat treatment temperature is not calculated.

[0101]

[0102] The above heat treatment can be performed, for example, at atmospheric pressure, and in this case, there is the advantage of reduced process costs and a safe process.

[0103] In this description, atmospheric pressure may be normal pressure, and 1 atm is used to refer to the pressure of air (atmosphere).

[0104]

[0105] The above heat treatment can be performed using various types of furnaces, for example, preferably with a box-type furnace, and more preferably with a rotary kiln. In this case, continuous processing is possible, productivity is excellent, and the reduction reaction can be promoted, which has the advantage of an excellent conversion rate to lithium compounds.

[0106]

[0107] For crushing the heat-treated material, a milling machine may be used, for example, and preferably a roll press, ball mill, or pin mill may be used, and more preferably a roll press may be used. In this case, the heat-treated material is uniformly crushed to increase the specific surface area, which has the advantage of allowing lithium to be easily dissolved in the subsequent process.

[0108] The above heat-treated material may have a particle size after crushing of, for example, 0.5 to 100 μm, preferably 3 to 70 μm, more preferably 3 to 50 μm, even more preferably 5 to 30 μm, and even more preferably 5 to 20 μm, and within this range, there is an advantage that lithium is easily dissolved in a subsequent process.

[0109] In this description, the particle size can be measured using a measurement method commonly used in the technical field to which the present invention belongs, and, for example, can be measured using a sieve.

[0110]

[0111] The above carbon-containing reducing agent can preferably be used in an amount of 0.3 to 3 moles per mole of cathode active material in the cathode material powder, more preferably 0.3 to 2 moles, even more preferably 0.7 to 1.5 moles, and even more preferably 0.9 to 1.2 moles, and within this range, there is an effect of high heat treatment efficiency and shortened reaction time.

[0112] In this description, the number of moles of the cathode active material in the cathode powder can be determined by assuming the entire cathode powder as the mass of the cathode active material, since the cathode powder contains a conductive material, a binder, and aluminum incorporated during the crushing and / or grinding process in addition to the cathode active material, but the amounts are trace and do not significantly affect the result.

[0113]

[0114] The above carbon-containing reducing agent may be, for example, an organic material containing carbon, an inorganic material containing carbon, a cathode material, or a mixture thereof, and preferably graphite, in which case there is an advantage of easily reacting with lithium in the cathode material of a lithium-ion battery.

[0115] The graphite above may preferably have a fixed carbon content of 90 weight% or more, more preferably 95 weight% or more, and even more preferably 98 weight% or more, and within this range, it has the advantage of being easy to react with lithium in the cathode material.

[0116] In this description, fixed carbon content (by weight) refers to the combustible residue remaining after volatile matter has evaporated from carbon, and represents the content excluding volatile matter, moisture, and ash from carbon.

[0117] The above graphite may preferably be graphite derived from the cathode material, in which case there is an advantage of reducing production costs and recycling resources.

[0118]

[0119] The above-mentioned cathode material may include, for example, one or more selected from the group consisting of lithium cobalt oxide; lithium manganese oxide; lithium iron phosphate compound; lithium nickel cobalt aluminum oxide; lithium nickel oxide; nickel manganese-based lithium composite metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn); and NCM-based lithium composite transition metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn) and cobalt (Co), and in this case, it has the effect of having excellent reversible capacity and thermal stability.

[0120] As another specific example, the above-mentioned cathode material is the following chemical formula 1

[0121] [Chemical Formula 1]

[0122] Li a Ni x Mn y Co z Mw O 2+δ

[0123] (In the above chemical formula 1, M comprises one or more selected from the group consisting of B, W, Al, Ti, and Mg, and 1 <a≤1.1, 0<x<0.95, 0<y<0.8, 0<z<1.0, 0≤w≤0.1, -0.02≤δ≤0.02, x+y+z+w=1이다.)로 표시되는 화합물을 포함할 수 있다.

[0124]

[0125] The above lithium-ion battery cathode may be, for example, a discarded lithium-ion battery cathode, and in this case, Ni, Co, Mn, etc., can be recovered along with expensive lithium, thus providing an economic advantage of resource recycling.

[0126]

[0127] (b) A step of obtaining a leaching solution in which a lithium component is dissolved from the cathode material powder

[0128] The lithium recovery method of the present invention includes the step of (b) obtaining a leaching solution in which a lithium component is dissolved from a cathode material powder. In this case, the process of purifying and filtering the lithium component by introducing it into a subsequent process, a flow-capacitive deionization device, is smoothly performed, and there is an advantage of increasing the purity and recovery rate of the recovered lithium.

[0129]

[0130] The cathode material powder introduced in step (b) above may be, for example, a cathode material powder obtained by crushing and / or grinding a lithium-ion battery cathode, or a cathode material powder obtained after heat-treating the cathode material powder with a carbon-containing reducing agent.

[0131]

[0132] In step (b) above, the leaching solution in which the lithium component is dissolved can be obtained by, for example, by leaching the cathode material powder obtained in step (a) with water to obtain the leaching solution in which lithium is dissolved and the leaching residue, and separating them (b-1). In this case, since acid is not used, it is environmentally friendly and production costs are reduced. Furthermore, since there are few impurities such as Ni, Co, and Mn in the leaching solution, high-purity lithium compounds can be recovered, and the leaching residue contains a large amount of Ni, Co, and Mn, etc., making it easy to manufacture as a precursor raw material, thus providing economic advantages.

[0133] In the above step (b-1), the cathode material powder may preferably be a cathode material powder obtained after heat-treating the cathode material powder with a carbon-containing reducing agent. In this case, lithium is dissolved without using acid, which is environmentally friendly, reduces production costs, and has the advantage of recovering a high-purity lithium compound with fewer impurities such as Ni, Co, and Mn in the leaching solution.

[0134] In the above (b-1) step, the cathode material may preferably include one or more selected from the group consisting of lithium cobalt oxide; lithium manganese oxide; lithium nickel cobalt aluminum oxide; lithium nickel oxide; a nickel manganese-based lithium composite metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn); and an NCM-based lithium composite transition metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn) and cobalt (Co). In this case, lithium is easily dissolved without using acid, which has the advantage of increasing the purity and recovery rate of lithium.

[0135]

[0136] The solid-liquid ratio of the above cathode material powder and water may be, for example, 1g / 20ml to 1g / 40ml, preferably 1g / 22ml to 1g / 37ml, more preferably 1g / 25ml to 1g / 35ml, and within this range, the lithium component is sufficiently dissolved, which has the advantage of increasing the recovery rate of lithium.

[0137] In this description, the solid-to-liquid ratio refers to the volume of liquid relative to the weight of the solid, that is, the volume of water (mL) relative to the content (g) of the cathode material powder.

[0138]

[0139] The above step (b-1) can be performed by adding water to the cathode material powder and stirring with a stirrer at, for example, 1°C to room temperature, preferably at room temperature, and in this case, there is an advantage of shortening the time for the lithium component to dissolve.

[0140] In this description, room temperature may be one point within the range of 20 ± 5 ℃.

[0141]

[0142] The above stirring speed may be, for example, 300 to 700 rpm, preferably 400 to 600 rpm, more preferably 450 to 550 rpm, and within this range, there is an advantage that the lithium component is easily leached from the cathode material powder.

[0143]

[0144] The above stirring time may be, for example, 0.5 hours or more, preferably 0.5 to 3 hours, more preferably 0.5 to 2.5 hours, and even more preferably 1 to 2 hours, and within this range, the lithium component is sufficiently dissolved in the cathode material powder, which has the advantage of recovering lithium with high purity and high recovery rate.

[0145]

[0146] The above water may be, for example, neutral water, preferably tap water, distilled water, or deionized water, and more preferably distilled water; in this case, it does not contain acid, allows lithium components to be easily leached, and has the effect of being environmentally friendly and reducing production costs.

[0147] The above-mentioned dissolution of the lithium component using water is carried out using water without using acid, for example, and thus has the advantage of easily recovering high-purity lithium because the leaching solution in which the lithium component is dissolved has a low content of impurities such as Ni, Co, and Mn.

[0148]

[0149] In the above step (b-1), the separation of the leachate and the leachate residue can be achieved by, for example, filtration, and preferably by vacuum filtration. In this case, the leachate and the leachate residue can be easily separated through a simple process, reducing process costs and providing an environmentally friendly advantage.

[0150] The above vacuum filtration may preferably be vacuum vacuum filtration, specifically vacuum vacuum filtration using a filtration flask, and in this case, there is an advantage that the leachate and leachate residue are easily separated.

[0151] In this description, vacuum reduced pressure filtration is not particularly limited to conventional vacuum reduced pressure filtration in the technical field to which the present invention belongs, and may include, for example, filtration in a partial vacuum state or a low pressure state.

[0152]

[0153] In addition, the leaching solution in which the lithium component is dissolved in step (b) above can be obtained by including step (b-2), for example, by adding cathode material powder to a mixture of an acidic solution and an oxidizing agent and leaching to obtain the leaching solution in which lithium is dissolved and the leaching residue, and separating them to obtain the leaching solution. In this case, there is an advantage of selectively leaching the lithium component.

[0154] In the above step (b-2), the cathode material powder may preferably be a cathode material powder obtained by crushing and / or grinding a lithium-ion battery cathode, and in this case, there is an advantage that the lithium is easily dissolved, thereby increasing the purity and recovery rate of the lithium.

[0155] In the above step (b-2), the cathode material powder may preferably be cobalt oxide; lithium manganese oxide; lithium iron phosphate compound; lithium nickel cobalt aluminum oxide; lithium nickel oxide; a nickel-manganese-based lithium composite metal oxide in which a portion of the nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn); and an NCM-based lithium composite transition metal oxide in which a portion of the nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn) and cobalt (Co). In this case, lithium is easily dissolved, which has the advantage of increasing the purity and recovery rate of lithium.

[0156]

[0157] The above acidic solution may have an acid concentration of, for example, 0.1 to 1.5 molar concentration (mol / L), preferably 0.2 to 1.3 molar concentration, more preferably 0.3 to 1.0 molar concentration, and even more preferably 0.4 to 0.8 molar concentration, within this range, the lithium component in the cathode material powder is selectively dissolved, and by using a low concentration of acid, the amount of wastewater generated is reduced, which has the advantage of being environmentally friendly.

[0158] The above acidic solution may, for example, contain 0.5 to 1.5 moles of acid, preferably 0.55 to 1.3 moles, and more preferably 0.60 to 1.2 moles per mole of positive active material in the positive material powder, and has the advantage of selectively leaching lithium components within this range.

[0159]

[0160] The above acidic solution is not limited to acidic components capable of adjusting the pH to 1 to 5 in a mixture of acidic solution and oxidizing agent, and, for example, may be a solution containing one or more selected from the group consisting of sulfuric acid, hydrochloric acid, hypochlorous acid, nitric acid, carbonic acid, acetic acid, and oxalic acid, preferably an aqueous solution, and preferably may be a solution containing hydrochloric acid or sulfuric acid, preferably an aqueous solution, in which case there is an advantage of selectively leaching lithium components.

[0161]

[0162] The above oxidizing agent can be introduced in an amount including, for example, 0.5 to 2.3 moles, preferably 0.7 to 2.2 moles, more preferably 1.0 to 2.2 moles, even more preferably 1.2 to 2.2 moles, even more preferably 1.5 to 2.2 moles, particularly preferably 1.8 to 2.2 moles, and particularly more preferably 1.9 to 2.1 moles per mole of positive active material in the positive material powder, and within this range, metal components excluding lithium components are precipitated and easily removed, which has the advantage of increasing the yield and purity of lithium.

[0163] The above oxidizing agent may be, for example, in a solid, liquid, or gaseous form, preferably in a liquid form, more preferably in a solution containing the oxidizing agent, and even more preferably in an aqueous solution containing the oxidizing agent, in which case there is an advantage of selectively recovering lithium.

[0164] The solution containing the above oxidizing agent may, for example, contain the oxidizing agent at a concentration of 20 to 40 weight%, preferably 25 to 35 weight%, more preferably 30 to 35 weight%, and within this range, there is an advantage that selective leaching of lithium is easy.

[0165]

[0166] The above oxidizing agent may include, for example, one or more selected from the group consisting of hydrogen peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, oxygen, and air, and preferably may be hydrogen peroxide, in which case there is an advantage of selectively leaching lithium components in the cathode material.

[0167] Preferably, the solution containing the oxidizing agent may be an aqueous hydrogen peroxide solution containing 20 to 40 weight%, more preferably 25 to 35 weight%, and even more preferably 30 to 35 weight% of hydrogen peroxide, in which case there is an advantage of selectively leaching the lithium component in the cathode material powder.

[0168]

[0169] The mixture of the acidic solution and the oxidizing agent may, for example, have a pH of 1 to 5, preferably 2 to 4, and more preferably 2 to 3. Within this range, the lithium component is easily dissolved, and the metal component other than lithium is precipitated and can be easily removed as a leaching residue.

[0170] In this description, pH measurement can be performed using measurement methods commonly used in the technical field to which this invention belongs, and unless otherwise specified, it can be measured using a general pH measuring device at room temperature, specifically using the Thermo Scientific Orion Star A Series.

[0171]

[0172] Step (b-2) above can be carried out at room temperature, for example, and in this case, metal components other than the lithium component are precipitated and easily removed, which has the advantage of increasing the yield and purity of lithium.

[0173] Step (b-2) above can be carried out, for example, under stirring, and in this case, there is an advantage that the time for the lithium component to dissolve and the metal component excluding the lithium component to precipitate is shortened.

[0174] The above stirring speed may be, for example, 300 to 700 rpm, preferably 350 to 650 rpm, more preferably 400 to 600 rpm, and even more preferably 450 to 550 rpm, and within this range, there is an advantage of easily dissolving the lithium component to obtain a leaching solution containing the lithium component and a leaching residue.

[0175] The above stirring time can be carried out for, for example, 10 to 60 minutes, preferably 20 to 50 minutes, more preferably 30 to 40 minutes, and within this range, there is an advantage of shortening the time for the lithium component to dissolve.

[0176] The separation of the leachate and leachate residue obtained in step (b-2) above can be achieved by, for example, filtration, and preferably by vacuum filtration. In this case, the leachate and leachate residue can be easily separated with only a simple process, reducing process costs and providing an environmentally friendly advantage.

[0177]

[0178] In addition, the leaching solution in which the lithium component is dissolved in step (b) above can be obtained by including step (b-3), for example, by adding an oxidizing agent to a solution in which cathode material powder is dissolved in an acidic solution to obtain a leaching solution in which lithium is dissolved and a leaching residue, and separating them to obtain a leaching solution, and in this case, there is an advantage of selectively leaching the lithium component.

[0179] In the above step (b-3), the cathode material powder may preferably be a cathode material powder obtained by crushing and / or grinding a lithium-ion battery cathode, and in this case, lithium is selectively and easily dissolved, which has the advantage of increasing the purity and recovery rate of lithium.

[0180] In the above step (b-3), the cathode material powder may preferably be a lithium iron phosphate compound, and in this case, lithium is selectively and easily dissolved, which has the advantage of increasing the purity and recovery rate of lithium.

[0181]

[0182] In step (b-3) above, the oxidizing agent can be added to the solution, for example, continuously or in batches, preferably continuously, and specifically continuously while stirring, in which case there is an advantage that lithium is sufficiently and selectively leached from the solution. For the batch addition, the oxidizing agent can be added in batches, for example, at the start of stirring or immediately before stirring, in which case there is an advantage that lithium is selectively leached.

[0183] In this description, the term "continuous feeding" means that it is not "batch feeding," and refers to feeding in a drop-by-drop, little-by-little, step-by-step, or continuous flow manner for at least 10 minutes, preferably at least 30 minutes, within the leaching time range.

[0184]

[0185] In step (b-3) above, the type, concentration, amount of acidic solution and oxidizing agent, and leaching conditions, etc., may be within the same category as step (b-2) of this description.

[0186]

[0187] The leaching solution obtained in step (b) above can be introduced into step (c) after performing step (b') to remove impurities, such as polyvalent cations, for example, and in this case, there is an advantage of further increasing the purity and recovery rate of the recovered lithium.

[0188]

[0189] The step of removing impurities (b') above may further perform a step (b'-1) of filtering the leachate with a nanofiltration membrane, for example. In this case, the purity and recovery rate of the recovered lithium are further increased as polyvalent cations are removed by the microporousness and pressure of the nanofiltration membrane.

[0190] The above nanofiltration membrane may, for example, have a molecular weight cutoff (MWCO) of 100 to 1,000 Da, preferably 200 to 700 Da, more preferably 200 to 500 Da, and in this case, there is an advantage that the purity of lithium is further improved by removing polyvalent cations such as Fe, Al, Ni, Co, or Mn.

[0191] In this description, the fractional molecular weight is measured indirectly because it is difficult to directly measure the size of the fine pores within the filtration membrane, and is defined as the minimum molecular weight of a solute that exhibits an exclusion rate of 90% or more by the membrane, serving as an indicator of separation performance in Dalton (Da), the unit of molecular weight. The fractional molecular weight can be measured by measurement methods commonly used in the technical field to which this invention belongs. Specifically, the molecular weight of the solute at which the removal rate of 1,000 mg / L of non-charged solute dissolved in a solvent is 90% or more when operating under conditions of a temperature of 25 ℃ and a pressure of 75 psig using a membrane evaluation device can be defined as the fractional molecular weight of the membrane.

[0192]

[0193] In addition, the above (b') impurity removal step may include, for example, a step (b'-2) of adding one or more impurity removal agents selected from the group consisting of lithium hydroxide (LiOH); a basic compound; a cathode material powder; and the remaining liquid after obtaining a lithium crystal salt from a purified lithium component; and in this case, the pH of the leaching solution is raised by adding the impurity removal agent, so that the impurities are easily removed by precipitating, thereby increasing the purity and recovery rate of lithium.

[0194] In the above step (b'-2), the basic compound may be, for example, a metal hydroxide, a metal carbonate, or a mixture thereof, and in this case, the polyvalent cation in the leaching solution is easily removed by precipitation, which has the advantage of increasing the purity and recovery rate of lithium.

[0195] In the above step (b'-2), the metal hydroxide may preferably be sodium hydroxide, potassium hydroxide, or a mixture thereof, and in this case, the polyvalent cation in the leaching solution is easily removed by precipitation, which has the advantage of increasing the purity and recovery rate of lithium.

[0196] The above metal carbonate may preferably be sodium carbonate, potassium carbonate, or a mixture thereof, and in this case, there is an advantage that the purity and recovery rate of lithium are increased as polyvalent cations in the leaching solution are easily removed by precipitation.

[0197]

[0198] In step (b'-2) above, the lithium hydroxide may be, for example, 0.05 to 0.3 moles, preferably 0.10 to 0.25 moles, more preferably 0.15 to 0.20 moles per mole of positive electrode active material in the leaching solution, and within this range, the polyvalent cation in the leaching solution is easily removed by precipitation, which has the advantage of increasing the purity and recovery rate of lithium.

[0199] In step (b'-2) above, the basic compound may be, for example, 0.05 to 0.3 moles, preferably 0.10 to 0.25 moles, more preferably 0.15 to 0.20 moles per 1 mole of positive electrode active material in the leaching solution, and within this range, the polyvalent cation in the leaching solution is easily removed by precipitation, which has the advantage of increasing the purity and recovery rate of lithium.

[0200]

[0201] The above impurity remover can be added, for example, to raise the pH of the leaching solution to pH 3 or higher, preferably pH 4 or higher, more preferably pH 5 or higher, even more preferably pH 6 or higher, even more preferably pH 6 to 9, and particularly preferably pH 6 to 8. In this case, the polyvalent cations are precipitated and easily removed, which has the advantage of increasing the purity and recovery rate of lithium.

[0202]

[0203] In step (b'-2) above, the cathode material powder, which is an impurity remover, may preferably be a cathode material powder obtained by crushing and / or grinding a lithium-ion battery cathode. In this case, the cathode material powder contains a large amount of lithium, so when it is added to the leaching solution, the pH of the leaching solution rises, causing polyvalent cations to precipitate and be easily removed, which has the advantage of increasing the purity and recovery rate of lithium.

[0204] As an impurity remover, the cathode material powder can be added in an amount containing, for example, 0.1 to 0.7 moles, preferably 0.2 to 0.5 moles, and more preferably 0.2 to 0.3 moles of lithium in the cathode material powder per 1 mole of lithium in the leaching solution. Within this range, the pH of the leaching solution increases, so that polyvalent cations such as Fe, Al, Ni, Co, or Mn are precipitated and easily removed, thereby increasing the purity and recovery rate of lithium.

[0205] When the cathode material powder is added as the above impurity remover, H in the leaching solution reacts further with unreacted acid components and oxidizing agents in the leaching solution. + It is consumed, and the pH rises.

[0206]

[0207] In the above step (b'-2), the filtrate is preferably the filtrate remaining after obtaining a lithium crystalline salt from a purified lithium component, specifically the filtrate remaining after obtaining a lithium component purified through a flow capacitive deionization device and obtaining it as a lithium crystalline salt. Since this contains a small amount of lithium, when it is added to the leaching solution, the pH of the leaching solution rises, causing polyvalent cations to precipitate and be easily removed, thereby providing the advantage of increasing the purity and recovery rate of lithium.

[0208] Since the above filtrate is a solution in which lithium carbonate and / or lithium hydroxide is dissolved and exhibits basicity, when it is added to the leaching solution as an impurity remover, it dilutes the leaching solution while simultaneously producing H through a reaction such as Reaction Scheme 1 or 2 below. + Consuming it raises the pH.

[0209] [Reaction Equation 1]

[0210] CO3 2- + 2H + <--> HCO3 - + H + <--> H2CO3 <--> CO2 + H2O

[0211] H+ + OH - --> H2O

[0212] [Reaction Equation 2]

[0213] CO3 2- + H2O <--> HCO3 - + OH -

[0214]

[0215] The above filtrate can be introduced in an amount containing, for example, 0.2 to 0.8 moles of lithium in the filtrate, preferably 0.3 to 0.7 moles, and more preferably 0.4 to 0.6 moles, for every 1 mole of lithium in the leaching solution. Within this range, the pH of the leaching solution increases, and polyvalent cations such as Fe, Al, Ni, Co, or Mn are precipitated and easily removed, thereby having the advantage of increasing the purity and recovery rate of lithium.

[0216]

[0217] In the above (b') impurity removal step, the leaching solution into which the impurity removal agent is added may have a pH of, for example, 3 or higher, preferably 4 or higher, more preferably 5 or higher, even more preferably 6 or higher, even more preferably 6 to 9, and particularly preferably 6 to 8, and there is an advantage that the purity and recovery rate of lithium are improved as impurities are easily removed by precipitating within this range.

[0218]

[0219] (c) a step of purifying the lithium component by introducing the obtained leaching solution into a flow capacitive deionization device.

[0220] The lithium recovery method of the present invention may include (c) a step of purifying the lithium component of the obtained leaching solution through a flow capacitive deionization device to obtain a lithium concentrate, and in this case, the lithium component can be efficiently purified through a simple and continuous process compared to existing processes, and there are advantages such as reduced process costs and energy, and increased purity and yield of lithium.

[0221]

[0222] In step (c) above, the leaching solution introduced into the flow capacitive deionization device may, for example, have a total metal component excluding lithium of 1 weight% or less, preferably 0.01 to 1 weight%, and there is an advantage that the purity and yield of the recovered lithium are increased within this range.

[0223] In this description, the content of lithium or metal components can be measured by measurement methods commonly used in the technical field to which the present invention belongs, and specifically, can be measured through ICP analysis. A specific measurement example is to take 0.2 g of the leachate, place it in a conical tube, and measure the exact weight, then add 0.1 ml of nitric acid with a concentration of 70 wt% to it, add 500 µl of 1000 mg / kg internal STD (Sc), and dilute with ultrapure water to 50 ml for measurement by ICP analysis; if necessary, further dilution with ultrapure water may be performed so that the sample concentration falls within the standard substance calibration curve.

[0224]

[0225] In step (c) above, the flow capacitive deionization device may include, for example, a lithium leaching solution circulation tank; an anion adsorption unit including a negative film flow electrode circulation tank, a current collector, and an anion exchange membrane; a cation adsorption unit including a cation exchange membrane, a current collector, and an positive film flow electrode circulation tank; a cation desorption unit including a current collector and a cation exchange membrane; and a cation collection unit including a deionized water circulation tank, an anion exchange membrane, a current collector, and a negative film flow electrode circulation tank; and in this case, by utilizing the principles of electrochemical ion adsorption and desorption, it is possible to obtain lithium with high purity and high recovery rate through a simpler and continuous process compared to conventional methods, thereby providing the advantage of reducing process costs and energy.

[0226] The above-described flow-capacitive deionization device may preferably include two or more anion adsorption units, cation adsorption units, and cation desorption units, respectively, and in this case, there is an advantage of further improving productivity.

[0227]

[0228] The above-described flow-capacitance deionization device may, for example, have a lithium leaching solution circulation tank, a negative membrane flow electrode circulation tank within an anion adsorption section, a positive membrane flow electrode circulation tank, a negative membrane flow electrode circulation tank within a cation collection section, and a deionized water circulation tank each connected to a pump to circulate individually, and ions can be separated by the current and / or voltage applied to the current collector. The flow rate of the pump and the applied current and / or voltage can be adjusted according to the size of the current collector, the performance of the cation exchange membrane and anion exchange membrane, the capacity of the flow electrode and the lithium leaching solution, etc.

[0229] The above-mentioned amniotic flow electrode circulation tank can, for example, share an amniotic flow electrode in which lithium cations are adsorbed in a cation adsorption section and an amniotic flow electrode in which lithium cations are adsorbed in a cation desorption section, and in this case, a continuous process is possible, which has the advantage of improving productivity.

[0230] The above pump may preferably be a metering pump.

[0231]

[0232] The above cation exchange membrane is, for example, -SO3 as a fixed charge or functional group. - , -COOH - , -PO3 2- and -PO3H - It may include one or more selected from the group consisting of, preferably -SO3 - It may include, in this case, the advantage is that high-purity lithium components are obtained by easily passing lithium cations through and attaching or detaching them from the amniotic membrane flow electrode.

[0233] In this document, the cation exchange membrane is also referred to as the amniotic membrane.

[0234]

[0235] The above anion exchange membrane is, for example, -NH3 as a fixed charge or functional group. + , -NRH2 + , -NR2H + and -NR3 +It may include one or more selected from the group consisting of, preferably -NH3 + It may include, in this case, anionic impurities in the leaching solution can be easily passed through and attached to the negative film flow electrode, thereby increasing the purity of lithium.

[0236] In this description, the anion exchange membrane is also referred to as a negative membrane.

[0237]

[0238] The above current collector may be one or more selected from the group consisting of graphite, SUS (Steel Use Stainless), nickel, copper, and platinum, and preferably graphite, in which case it has the effect of allowing the flow electrode to move easily.

[0239]

[0240] The above lithium leaching solution circulation tank, the negative film flow electrode circulation tank in the anion adsorption section, the positive film flow electrode circulation tank in the cation adsorption section, the deionized water circulation tank, and the negative film flow electrode tank in the cation collection section may preferably be tanks in an electrically insulated state, and in this case, there is an advantage that cations or anions are not attached to the tanks and are recirculated.

[0241]

[0242] In step (c) above, the flow capacitive deionization device may include, for example, a step of passing a leaching solution in which a lithium component is dissolved between an anion adsorption unit including a negative film flow electrode and a cation adsorption unit including a positive film flow electrode to adsorb lithium cations onto the positive film flow electrode; a step of passing the positive film flow electrode on which lithium cations are adsorbed between a current collector and a cation exchange membrane to desorb lithium cations from the positive film flow electrode; and a step of collecting the desorbed lithium cations as deionized water. In this case, lithium is recovered with high purity by purifying and concentrating the lithium component using the electrochemical ion adsorption and desorption principles, and compared to conventional methods, the process is simple and continuous operation is possible, which is efficient and reduces process costs and energy.

[0243]

[0244] The above-described flow capacitive deionization device may perform a step of adsorbing lithium cations from a lithium leaching solution onto a positive film flow electrode using one module comprising, for example, a lithium leaching solution circulation tank, a negative film flow electrode circulation tank, a current collector, and an anion exchange membrane; and a cation adsorption unit comprising a cation exchange membrane, a current collector, and a positive film flow electrode circulation tank. Then, in the one module, the cation adsorption unit is used as a cation desorption unit and the anion adsorption unit is used as a cation collection unit to perform a step of desorbing and recovering lithium from the positive film flow electrode on which lithium cations have been adsorbed. In this case, there is an effect of reducing equipment costs.

[0245]

[0246] Specifically, the step of adsorbing lithium cations in the above-mentioned leaching solution involves passing the leaching solution between an anion adsorption section including a negative film flow electrode and a cation adsorption section including an amphoteric film flow electrode; the lithium cations in the leaching solution pass through a cation exchange membrane via a negatively charged current collector and are adsorbed onto the amphoteric film flow electrode, then move together with the amphoteric film flow electrode to the amphoteric film flow electrode circulation tank to collect the lithium cations, after which the amphoteric film flow electrode circulates to repeat the step of adsorbing lithium cations onto the amphoteric film flow electrode; and the anions in the leaching solution pass through an anion exchange membrane via a positively charged current collector and are adsorbed onto the negative film flow electrode, then move together with the negative film flow electrode to the amphoteric film flow electrode circulation tank to collect the anions, after which the negative film flow electrode circulates again to repeat the step of adsorbing anions onto the negative film flow electrode; in this case, the lithium cations in the leaching solution and F - , PO4 3- , SO4 2- , Cl - The anions are easily separated and collected in the positive membrane flow electrode circulation tank and the negative membrane flow electrode circulation tank, respectively, thereby having the effect of recovering high-purity lithium.

[0247] In the above-mentioned negative membrane flow electrode circulation tank, for example, F - , PO4 3- , SO4 2- , Cl - There is an advantage in that the purity of lithium is improved as negative ions are collected.

[0248] The step of adsorbing lithium cations in the above-mentioned leaching solution may, for example, include placing a spacer between the anion separator and the cation separator, and in this case, the lithium cations and anions from the leaching solution are sufficiently adsorbed onto the positive and negative flow electrodes, respectively.

[0249]

[0250] In this description, the term "module" is not particularly limited to modules commonly used in the technical field to which the present invention belongs, and may refer, for example, to a configuration designed to be independently installed, replaced, and / or used within a process, device, or system.

[0251]

[0252] The step of desorbing lithium cations from the above-mentioned amphoteric flow electrode on which lithium cations are adsorbed is specifically such that when the amphoteric flow electrode on which lithium cations are adsorbed is passed between a positively charged current collector and a cation exchange membrane, the lithium cations are desorbed from the amphoteric flow electrode and pass through the cation exchange membrane, thereby purifying and filtering the lithium component and recovering high-purity lithium.

[0253] The step of desorbing lithium cations from the above-mentioned amphoteric flow electrode on which lithium cations are adsorbed may, for example, involve placing a spacer between the cation separator and the anion separator, and in this case, the lithium cations are sufficiently desorbed from the amphoteric flow electrode on which lithium cations are adsorbed, thereby having the effect of recovering high-purity lithium.

[0254]

[0255] The above spacer is not particularly limited to any spacer defined or used in the technical field to which the present invention belongs.

[0256]

[0257] The step of collecting the above-mentioned desorbed lithium cations into deionized water has the effect of recovering high-purity lithium by purifying and filtering the lithium components simultaneously, for example, by repeating the step in which the desorbed lithium cations combine with anions that have passed through an anion exchange membrane and are collected together with deionized water into a deionized water circulation tank.

[0258] The step of collecting the above-mentioned desorbed lithium cations into deionized water is, specifically, a step in which the desorbed lithium cations pass between the negative membrane flow electrode in the cation collection section and the negative (-) charged current collector, combine with the anions that have passed through the negative membrane, and are collected together with the deionized water in a deionized water circulation tank, thereby purifying and filtering the lithium components at the same time, and thus having the effect of recovering high-purity lithium.

[0259] The step of collecting the desorbed lithium cations with deionized water is, more specifically, when the negative membrane flow electrode in the cation collection unit includes deionized water, distilled water, or a mixture thereof as a solvent, the desorbed lithium cations pass between the negative membrane flow electrode in the cation collection unit and the anion exchange membrane and the negatively charged current collector, and the OH that has passed through the anion exchange membrane - By repeating the step of combining with and collecting in the form of LiOH along with deionized water in a deionized water circulation tank, the lithium component is purified and filtered simultaneously, thereby having the effect of recovering high-purity lithium.

[0260]

[0261] In addition, negative membrane flow electrodes that did not pass through the above-mentioned anion exchange membrane are recovered and recirculated to the negative membrane flow electrode circulation tank within the cation collection unit.

[0262]

[0263] The above-described flow-capacitance deionization device may further include, for example, an adsorbed negative film flow electrode regeneration unit, and in this case, there is an advantage of continuously operating the process without replacing the negative film flow electrode on which the negative ions are adsorbed.

[0264]

[0265] The above-mentioned adsorption negative film flow electrode regeneration unit may include, for example, a negative (-) charged current collector, an anion exchange membrane, a cation exchange membrane, and a positive (+) charged current collector. In this case, there is an advantage that a continuous process is possible by desorbing the negative ions from the negative film flow electrode on which the negative ions are adsorbed in the anion adsorption unit and collecting them as deionized water.

[0266] The step of desorbing anions from the negative film flow electrode on which the anions are adsorbed may, for example, include the step of desorbing anions from the negative film flow electrode by passing the negative film flow electrode on which anions adsorbed, collected in the negative film flow electrode circulation tank within the anion adsorption section, between a negatively charged current collector and an anion exchange membrane, and separating the desorbed anions by passing them between a positively charged current collector and a cation exchange membrane, and collecting the cations that have passed through the cation exchange membrane and deionized water; in this case, F from the negative film flow electrode - , PO4 3- , SO4 2- , Cl - By desorbing negative ions, the negative film flow electrode in the negative ion adsorption section can be used continuously without replacement, resulting in excellent productivity.

[0267] The step of desorbing anions from the negative membrane flow electrode on which the anions are adsorbed is specifically to desorb anions from the negative membrane flow electrode by passing the negative membrane flow electrode, on which anions adsorbed and collected in the negative membrane flow electrode circulation tank within the anion adsorption section, between a negatively charged current collector and an anion exchange membrane, and the desorbed anions are separated as deionized water circulating between a positively charged current collector and a cation exchange membrane passes through, and H₂ that has passed through the cation exchange membrane + , and can be collected as deionized water passing between the cation exchange membrane and the anion exchange membrane, in this case, the desorbed F - , PO4 3- , SO4 2- , Cl - Anions such as H +By combining with and collecting deionized water in the form of H2SO4, HF, HCl, H3PO4, etc., it is possible to use it continuously without replacing the negative membrane flow electrode in the anion adsorption section, which has the effect of excellent productivity.

[0268]

[0269] The above positive or negative flow electrode may be composed of, for example, an active material, a conductive additive, and a solvent, and in this case, there is an advantage of easily separating lithium cations and anions, which are impurities, and collecting lithium cations with high purity.

[0270]

[0271] The above active material may be one or more selected from the group consisting of, for example, activated carbon, carbon beads, mesoporous carbon, carbon nanotubes, graphene, and MnO2, and in this case, the purity and recovery rate of the recovered lithium are increased by facilitating the adsorption and desorption of lithium components.

[0272]

[0273] The conductive additive may be one or more selected from the group consisting of carbon black, carbon nanotubes, graphene, and reduced graphene oxide (rGO), for example, and may not be the same as the active material, and in this case, the purity and recovery rate of the recovered lithium are increased by facilitating the adsorption and desorption of the lithium component.

[0274]

[0275] The above solvent may be, for example, a sodium chloride (NaCl) solution, deionized water, or distilled water, and in this case, there is an advantage in that the purity and recovery rate of the recovered lithium are increased by facilitating the adsorption and desorption of lithium components.

[0276] The above sodium chloride solution may preferably be an aqueous sodium chloride solution.

[0277]

[0278] The above active material and conductive additive may be in the form of a slurry mixed in a solvent, for example, and in this case, the movement of the flow electrode is smooth, and the current collection capacity and ion selectivity are increased.

[0279]

[0280] The active material, conductive additive, and solvent in the above-mentioned positive and negative flow electrodes may, for example, be the same or different.

[0281]

[0282] (d) A step of obtaining the purified lithium component as a lithium crystal salt

[0283] The lithium recovery method of the present invention includes (d) a step of obtaining a purified lithium component as a lithium crystalline salt, and in this case, there is an advantage of significantly reducing the energy, cost, and time required to purify and concentrate lithium to recover it as a powder.

[0284]

[0285] The above lithium crystal salt may be one or more selected from the group consisting of, for example, lithium hydroxide (LiOH), lithium carbonate (Li2CO3), lithium chloride (LiCl), lithium sulfate (Li2SO4), and lithium nitrate (LiNO3), and preferably may be lithium hydroxide (LiOH) or lithium carbonate (Li2CO3), in which case there is an advantage of significantly reducing the energy, cost, and time required for lithium recovery.

[0286]

[0287] In the present invention, the step of obtaining a lithium component as a lithium crystalline salt can utilize methods commonly used in the technical field to which the present invention belongs. For example, the lithium component can be obtained by carbonating it to convert it into lithium carbonate. In this case, there is an advantage in that the energy, cost, and time required to purify and concentrate the lithium and recover it as a powder are significantly reduced.

[0288] The above carbonation can be carried out, for example, by introducing carbonate or carbon dioxide gas. In this case, the lithium component is converted into lithium carbonate to recover it at a high yield, and there is an advantage of reducing the energy, cost, and time required for purification and concentration to recover lithium.

[0289]

[0290] The above carbonate may be one or more selected from the group consisting of, for example, sodium carbonate, ammonium carbonate, and potassium carbonate, and preferably may be sodium carbonate. In this case, the lithium component is changed to lithium carbonate to recover it with high purity, and there is an advantage of reducing the energy, cost, and time required for concentration to recover lithium.

[0291] The above carbonate can be added, for example, in an amount of 0.8 to 1.5 moles, preferably 0.9 to 1.3 moles, and more preferably 1.0 to 1.2 moles per 1 mole of lithium component, and within this range, there is an excellent advantage of conversion to lithium carbonate.

[0292] The above carbon dioxide may be, for example, carbon dioxide, and in this case, the lithium component is changed to lithium carbonate to recover it at a high yield, and there is an advantage of reducing the energy, cost, and time required for concentration to recover lithium.

[0293] For example, the above carbon dioxide can be introduced in an amount greater than that capable of carbonating the lithium component obtained after purifying the lithium component through a flow capacitive deionization device in step (c), and in this case, there is an advantage of recovering lithium with high purity.

[0294] The above lithium component may include a step of carbonating and then heating, for example.

[0295] The heating above can be carried out, for example, at a temperature of 65 to 95 ℃, preferably 70 to 90 ℃, more preferably 75 to 85 ℃, and within this range, there is an advantage of easily recovering the lithium component in the form of lithium carbonate.

[0296] The heating above can be carried out for, for example, 40 to 80 minutes, preferably 45 to 75 minutes, more preferably 50 to 70 minutes, and within this range, there is an advantage of easily recovering the lithium component in the form of lithium carbonate.

[0297]

[0298] As a specific example of the above carbonation process, the purified lithium component exists as a concentrate of LiOH and Li2CO3. When carbon dioxide (CO2) or Na2CO3 is introduced to carbonate it, it becomes Li3CO3 and LiHCO3. When heated, a Li2CO3 solution and a crystalline salt in the form of Li2CO3 are obtained. Lithium is recovered as a crystalline salt in the form of Li2CO3 through solid-liquid separation. In this case, there is an advantage of significantly reducing energy, cost, and time compared to conventional heating or vacuum evaporation crystallization processes used to recover lithium components as powder.

[0299]

[0300] In step (d) above, after obtaining the purified lithium component as a lithium crystal salt, the remaining liquid can be recirculated and reused, for example, to the flow capacitive deionization device of step (c), and in this case, the lithium remaining in the liquid is purified, thereby maximizing the lithium recovery rate.

[0301] In addition, in step (d) above, the filtrate remaining after obtaining the purified lithium component as a lithium crystal salt can be introduced, for example, into the impurity removal step (b') above. In this case, the lithium component remaining in the filtrate raises the pH of the leaching solution, thereby precipitating polyvalent cations for easy removal and reducing process costs.

[0302]

[0303] The lithium crystal salt obtained in step (d) above may, for example, have a lithium purity of 99 weight% or more, preferably 99.5 weight% or more, and in this case, there is an advantage that high-purity lithium is recovered.

[0304] In this description, the purity of lithium is defined or calculated as shown in Equation 1 below, and can be measured by measurement methods commonly used in the technical field to which the present invention belongs, and as a specific example, can be measured through ICP analysis. A specific measurement example involves taking 0.1 g of a sample, placing it in a conical tube, and accurately weighing it. Then, 1.0 ml of nitric acid with a concentration of 70 wt% is added to the sample, and the solution is diluted with ultrapure water to a volume of 10 ml. The content of Li, Ni, Co, Mn, Fe, P, and Al is measured through ICP-OES analysis. If necessary, the sample concentration is further diluted with ultrapure water so that it falls within the standard material calibration curve, and the content (ppm) of Li, Ni, Co, Mn, Fe, P, and Al is measured.

[0305] In this document, % and ppm are based on weight unless otherwise defined.

[0306]

[0307] [Mathematical Formula 1]

[0308] Lithium Purity (weight%) = 100 weight% - Total of Components Excluding Lithium (weight%)

[0309]

[0310] In addition, the lithium recovery device of the present invention may include, for example, a lithium leaching solution circulation tank; an anion adsorption unit comprising a negative film flow electrode circulation tank, a current collector, and an anion exchange membrane; a cation adsorption unit comprising a cation exchange membrane, a current collector, and an positive film flow electrode circulation tank; a cation desorption unit comprising a current collector and a cation exchange membrane; and a cation collection unit comprising a deionized water circulation tank, an anion exchange membrane, a current collector, and a negative film flow electrode circulation tank. In this case, the lithium cations contained in the lithium leaching solution move to the positive film flow electrode circulation tank via the cation exchange membrane of the adsorption unit, and then pass through the cation exchange membrane of the desorption unit to be collected in the deionized water circulation tank of the collection unit. In this case, the lithium components in the leaching solution can be easily purified through the adsorption and desorption processes, and the process is simple and continuous, which has the effect of reducing process costs and energy.

[0311]

[0312] In addition, the lithium recovery method of the present invention may include, for example, (a) a step of obtaining a cathode material powder by crushing and / or grinding a lithium-ion battery cathode; (a') a step of obtaining a heat-treated product by heat-treating the obtained cathode material powder together with a carbon-containing reducing agent, and obtaining a heat-treated cathode material powder by crushing the obtained heat-treated product; (b) a step of obtaining a leaching solution in which a lithium component is dissolved by adding the heat-treated cathode material powder to water; (c) a step of purifying the lithium component from the obtained leaching solution through a flow-capacitive deionization device; and (d) a step of obtaining the purified lithium component as a lithium crystalline salt. In this case, the removal of impurities, especially anionic impurities, is excellent through a flow capacitive deionization device, which is an electrochemical adsorption and desorption process, thereby recovering lithium with high purity. Furthermore, the lithium recovery rate is maximized by recirculating the remaining liquid or lithium-containing waste liquid after obtaining the purified lithium component as a lithium crystal salt. Additionally, the process is simplified, energy is saved, and the amount of wastewater generated can be reduced, which provides environmentally friendly advantages.

[0313] The above-mentioned cathode material may include, for example, one or more selected from the group consisting of lithium cobalt oxide; lithium manganese oxide; lithium nickel cobalt aluminum oxide; lithium nickel oxide; nickel manganese-based lithium composite metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn); and NCM-based lithium composite transition metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn) and cobalt (Co). Preferably, it may include an NCM-based lithium composite transition metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn) and cobalt (Co). In this case, the generation of wastewater is reduced because an acidic solution is not used, and there is an advantage of simplifying the process because an impurity removal process is not required to remove multivalent cations such as Fe, Al, Ni, Co, or Mn due to high selectivity of lithium.

[0314]

[0315] In addition, the lithium recovery method of the present invention may include, for example, (a) a step of crushing and / or grinding a lithium-ion battery cathode to obtain cathode material powder; (b) a step of introducing the obtained cathode material powder into a mixture of an acidic solution and an oxidizing agent and leaching to obtain a leaching solution in which lithium is dissolved and a leaching residue, and separating them to obtain a leaching solution; (b') a step of filtering the obtained leaching solution through a nanofiltration membrane to obtain a filtered leaching solution; (c) a step of purifying the lithium component of the obtained filtered leaching solution through a flow capacitive deionization device; and (d) a step of obtaining the purified lithium component as a lithium crystalline salt.

[0316] In the above method for recovering lithium, for example, in step (d), after obtaining the purified lithium component as a lithium crystal salt, the remaining liquid can be fed into the flow capacitive deionization device of step (c) and reused.

[0317] The above-mentioned cathode material may include, for example, one or more selected from the group consisting of lithium cobalt oxide; lithium manganese oxide; lithium iron phosphate compound; lithium nickel cobalt aluminum oxide; lithium nickel oxide; nickel manganese-based lithium composite metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn); and NCM-based lithium composite transition metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn) and cobalt (Co). Preferably, it may include an NCM-based lithium composite transition metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn) and cobalt (Co), a lithium iron phosphate compound, or a mixture thereof. In this case, high-purity lithium is recovered by removing polyvalent cations such as Fe, Al, Ni, Co, or Mn contained in the leaching solution through a nanofiltration membrane.

[0318]

[0319] In addition, the lithium recovery method of the present invention may include, for example, (a) a step of obtaining a cathode material powder by crushing and / or grinding a lithium-ion battery cathode; (b) a step of dissolving the obtained cathode material powder in an acidic solution to obtain a solution, adding an oxidizing agent to the solution and leaching to obtain a leaching solution containing dissolved lithium and a leaching residue, and separating them to obtain a leaching solution; (b') a step of filtering the obtained leaching solution through a nanofiltration membrane to obtain a filtered leaching solution; (c) a step of purifying the lithium component of the obtained filtered leaching solution through a flow capacitive deionization device; and (d) a step of obtaining the purified lithium component as a lithium crystalline salt.

[0320] In the above method for recovering lithium, for example, in step (d), after obtaining the purified lithium component as a lithium crystal salt, the remaining liquid can be fed into the flow capacitive deionization device of step (c) and reused.

[0321]

[0322] In addition, the lithium recovery method of the present invention comprises, for example, (a) a step of crushing and / or grinding a lithium-ion battery cathode to obtain cathode material powder; (b) a step of introducing the obtained cathode material powder into a mixture of an acidic solution and an oxidizing agent and leaching to obtain a leaching solution in which lithium is dissolved and a leaching residue, and separating them to obtain a leaching solution; (b') a step of introducing an impurity removal agent into the obtained leaching solution to remove impurities; (c) a step of purifying the lithium component from the leaching solution from which impurities have been removed through a flow capacitive deionization device; and (d) a step of obtaining the purified lithium component as a lithium crystalline salt; wherein the impurity removal agent may be lithium hydroxide (LiOH) or a basic compound.

[0323] In the above method for recovering lithium, for example, in step (d), after obtaining the purified lithium component as a lithium crystal salt, the remaining liquid can be fed into the flow capacitive deionization device of step (c) and reused.

[0324] In step (b) above, the cathode material powder obtained as another example is dissolved in an acidic solution to obtain a solution, an oxidizing agent is added to the solution and leached to obtain a leached solution containing dissolved lithium and a leaching residue, and these are separated to obtain a leached solution.

[0325] The above-mentioned cathode material may include, for example, one or more selected from the group consisting of lithium cobalt oxide; lithium manganese oxide; lithium iron phosphate compound; lithium nickel cobalt aluminum oxide; lithium nickel oxide; nickel manganese-based lithium composite metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn); and NCM-based lithium composite transition metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn) and cobalt (Co). Preferably, it may include an NCM-based lithium composite transition metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn) and cobalt (Co), a lithium iron phosphate compound, or a mixture thereof. In this case, lithium hydroxide (LiOH) or a basic compound is added to the leaching solution to raise the pH of the leaching solution, thereby precipitating and removing polyvalent cations such as Fe, Al, Ni, Co, or Mn, which has the effect of recovering high-purity lithium.

[0326]

[0327] In addition, the lithium recovery method of the present invention comprises, for example, (a) a step of crushing and / or grinding a lithium-ion battery cathode to obtain cathode material powder; (b) a step of introducing the obtained cathode material powder into a mixture of an acidic solution and an oxidizing agent and leaching to obtain a leaching solution in which lithium is dissolved and a leaching residue, and separating them to obtain a leaching solution; (b') a step of introducing an impurity removal agent into the obtained leaching solution to precipitate and remove impurities; (c) a step of purifying the lithium component from the leaching solution from which impurities have been removed through a flow capacitive deionization device; and (d) a step of obtaining the purified lithium component as a lithium crystalline salt; wherein the impurity removal agent may be the liquid remaining after obtaining the purified lithium component as a lithium crystalline salt in step (d).

[0328] In step (b) above, the cathode material powder obtained as another example is dissolved in an acidic solution to obtain a solution, an oxidizing agent is added to the solution and leached to obtain a leached solution containing dissolved lithium and a leaching residue, and these are separated to obtain a leached solution.

[0329] The above cathode material may comprise, for example, one or more selected from the group consisting of lithium cobalt oxide; lithium manganese oxide; lithium iron phosphate compound; lithium nickel cobalt aluminum oxide; lithium nickel oxide; nickel-manganese-based lithium composite metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn); and NCM-based lithium composite transition metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn) and cobalt (Co). Preferably, it may comprise an NCM-based lithium composite transition metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn) and cobalt (Co), a lithium iron phosphate compound, or a mixture thereof. In this case, the pH of the leaching solution is raised by recovering and adding the remaining filtrate after changing from a lithium concentrate to a lithium crystalline salt to the leaching solution, thereby F - , PO4 3- , SO4 2- , Cl - The precipitation of polyvalent ions facilitates the easy removal of impurities, thereby having the effect of recovering high-purity lithium.

[0330]

[0331] In addition, the lithium recovery method of the present invention comprises, for example, (a) a step of crushing and / or grinding a lithium-ion battery cathode to obtain cathode material powder; (b) a step of introducing the obtained cathode material powder into a mixture of an acidic solution and an oxidizing agent and leaching to obtain a leaching solution in which lithium is dissolved and a leaching residue, and separating them to obtain a leaching solution; (b') a step of introducing an impurity removal agent into the obtained leaching solution to precipitate and remove impurities; (c) a step of purifying the lithium component from the leaching solution from which impurities have been removed through a flow capacitive deionization device; and (d) a step of obtaining the purified lithium component as a lithium crystalline salt; wherein the impurity removal agent may be the cathode material powder.

[0332] In step (b') above, the cathode material powder that is an impurity remover may be, for example, a cathode material powder obtained by crushing and / or grinding a lithium-ion battery cathode.

[0333] In the above method for recovering lithium, for example, in step (d), after obtaining the purified lithium component as a lithium crystal salt, the remaining liquid can be fed into the flow capacitive deionization device of step (c) and reused.

[0334] In step (b) above, the cathode material powder obtained as another example is dissolved in an acidic solution to obtain a solution, an oxidizing agent is added to the solution and leached to obtain a leached solution containing dissolved lithium and a leaching residue, and these are separated to obtain a leached solution.

[0335] The above-mentioned cathode material may comprise, for example, one or more selected from the group consisting of lithium cobalt oxide; lithium manganese oxide; lithium iron phosphate compound; lithium nickel cobalt aluminum oxide; lithium nickel oxide; nickel-manganese-based lithium composite metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn); and NCM-based lithium composite transition metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn) and cobalt (Co). Preferably, it may comprise an NCM-based lithium composite transition metal oxide in which a portion of nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn) and cobalt (Co), a lithium iron phosphate compound, or a mixture thereof. In this case, when cathode material powder obtained by crushing and / or grinding a lithium-ion battery cathode is introduced into a leaching solution, the pH of the leaching solution is raised due to a large amount of lithium in the cathode material powder, and F - , PO4 3- , SO4 2- , Cl - It has the effect of recovering high-purity lithium by removing multivalent ions such as those from the back through precipitation.

[0336]

[0337] Figure 7 below is a schematic diagram illustrating a process for purifying a lithium component by introducing a leaching solution in which a lithium component is dissolved into an anion adsorption unit, a cation adsorption unit, a cation desorption unit, and a cation collection unit into a flow capacitive deionization (FCDI) device, according to one embodiment of the present invention.

[0338] Specifically, Figure 7 below shows a process for purifying lithium components from a leaching solution in which lithium components are dissolved by connecting two modules, namely one module consisting of an anion adsorption unit and a cation adsorption unit, and one module consisting of a cation desorption unit and a cation collection unit, and in this case, there is an advantage of improved productivity.

[0339] More specifically, the above-described flow capacitive deionization (FCDI) device comprises: a lithium leaching solution circulation tank (11); an anion adsorption unit comprising a negative film flow electrode circulation tank (12), a current collector (100), and an anion exchange membrane (200); a cation adsorption unit comprising a cation exchange membrane (300), a current collector, and a positive film flow electrode circulation tank (13); a cation desorption unit comprising a current collector (100) and a cation exchange membrane (300); and a cation collection unit comprising a deionized water circulation tank (15), an anion exchange membrane (200), a current collector (100), and a negative film flow electrode circulation tank (14). Here, the anion adsorption unit and the cation adsorption unit are referred to as the adsorption unit (10), and the cation desorption unit and the cation collection unit are referred to as the desorption unit (20).

[0340]

[0341] In addition, Figure 8 below is a schematic diagram illustrating a process in which, according to one embodiment of the present invention, a leaching solution in which a lithium component is dissolved is introduced into a flow capacitive deionization unit comprising one module including an anion adsorption unit and a cation adsorption unit to adsorb lithium cations onto a positive membrane flow electrode, and then the cation adsorption unit is used as a cation desorption unit and the anion adsorption unit is used as a cation collection unit to desorb and recover lithium from the positive membrane flow electrode on which lithium cations are adsorbed.

[0342] Specifically, a flow capacitive deionization device consisting of one module comprises: a lithium leaching solution circulation tank (11); an anion adsorption unit including a negative film flow electrode circulation tank (12), a current collector (100), and an anion exchange membrane (200); and a cation adsorption unit including a cation exchange membrane (300), a current collector, and a positive film flow electrode circulation tank (13). After adsorbing lithium cations onto the positive film flow electrode, the cation adsorption unit is used as a cation desorption unit and the anion adsorption unit is used as a cation collection unit to desorb and recover lithium from the positive film flow electrode on which lithium cations have been adsorbed. In this case, there is an advantage of saving device costs and space.

[0343]

[0344] In addition, Figure 9 below is a schematic diagram illustrating a process in which an adsorption negative film flow electrode regeneration unit is added to a process for purifying a lithium component by introducing a leaching solution in which a lithium component is dissolved into a flow capacitive deionization device comprising an anion adsorption unit, a cation adsorption unit, a cation desorption unit, and a cation collection unit, as one embodiment according to the present invention.

[0345] Specifically, the adsorbed negative membrane flow electrode regeneration unit may include a current collector (100), a cation exchange membrane (300), an anion exchange membrane (200), and a current collector (100), and in this case, there is an advantage of continuously operating the process without replacing the negative membrane flow electrode on which anions are adsorbed.

[0346]

[0347] Referring to FIG. 1, first, a lithium-ion battery positive electrode is crushed and / or ground to prepare a positive electrode material powder (step S10).

[0348] Next, a leaching solvent is added to the cathode material powder to obtain a leaching solution in which the lithium component is dissolved and a leaching residue, and these are separated to obtain a leaching solution (step S20).

[0349] Next, the obtained leaching solution is fed into a flow capacitive deionization device to purify the lithium component (step S30).

[0350] Next, the purified lithium component is obtained as a lithium crystalline salt (step S40).

[0351]

[0352] Hereinafter, a method for recovering lithium will be explained in detail step by step through FIGS. 2 to 6.

[0353]

[0354] Referring to FIG. 2, first, a lithium-ion battery positive electrode is crushed and / or ground to prepare a positive electrode material powder (step S10).

[0355] The above waste lithium-ion battery cathode may preferably be a discarded lithium-ion battery cathode, a defective product generated during the cathode coating process, or a cathode scrap discarded after cutting the electrode plate, and preferably, a discarded lithium-ion battery cathode may be prepared.

[0356] The above-mentioned anode has a structure in which an anode active material layer comprising an anode active material and a conductive material is bonded to an aluminum foil by a binder.

[0357] The above positive active material may be an NCM-based lithium composite transition metal oxide.

[0358] First, to prepare the cathode material powder, the cathodes of spent lithium-ion batteries are crushed and ground into appropriate sizes.

[0359] Here, crushing involves cutting or shredding the anode into a size that is easy to handle. As a specific example, the crushed anode may be 1 cm x 1 cm in size. The crushing may be performed using various dry crushing equipment, such as a hand mill, pin mill, disc mill, cutting mill, hammer mill, or shredder, for example, or a high-speed cutter may be used to increase productivity.

[0360] The above crushing can preferably be performed or the size of the pieces can be determined by considering the characteristics required by the equipment used in the handling of the anode and subsequent processes. For example, if equipment capable of continuous processing is used, the anode must be crushed into smaller pieces because fluidity must be good.

[0361] Subsequently, the crushed anode is ground using, for example, a mixer, a hand mill, a pin mill, a disc mill, a cutting mill, or a hammer mill; specifically, when ground with a mixer, the current collector pieces are finely cut and the anode material separates from the current collector pieces.

[0362] The above-mentioned crushed cathode material is sieved to obtain cathode material powder. The sieve can be sieved, for example, with a mesh size of 30 to 500, and specifically, with a mesh size of 325.

[0363] The above sieving method has the advantage of obtaining powder of uniform size and separating the collector fragments.

[0364]

[0365] Next, the cathode material powder is heat-treated with a carbon-containing reducing agent (step S20).

[0366] Here, the cathode material of a lithium-ion battery undergoes complex processes during manufacturing, such as calcination, the addition of carbon and other metal oxides, and thermal fusion after the addition of a binder, in order to maintain or improve battery characteristics. For this reason, the discarded cathode material of a lithium-ion battery contains valuable metals in the form of various oxides and impurities, which can act as an impeding factor in the recovery of lithium and valuable metals. To eliminate these factors, heat treatment is performed at a high temperature by mixing with carbon to remove the binder added during the manufacturing of the cathode material and to reduce metallic substances combined with oxygen; this process is the heat treatment step.

[0367] The above heat treatment involves adding a carbon-containing reducing agent to the obtained anode powder and heat-treating it to obtain a heat-treated product.

[0368] The above carbon-containing reducing agent may be, for example, an organic material containing carbon, an inorganic material containing carbon, a cathode material, or a mixture thereof, and specifically, a graphite cathode material, in which case there is an advantage of being able to dissolve lithium from the anode material powder with water rather than an acidic solution.

[0369]

[0370] The above carbon-containing reducing agent is used in an amount of, for example, 0.3 to 3 moles based on 1 mole of the cathode active material in the cathode material powder, and specifically, 1 mole. In this case, the cathode material is sufficiently reduced, which has the advantage of easily dissolving the lithium component in a subsequent process.

[0371] The above heat treatment can be carried out, for example, under a reducing gas or an inert gas, preferably under an argon or nitrogen atmosphere, and specifically under a nitrogen atmosphere, in which case there is an advantage that the cathode material is easily reduced. At this time, the flow rate of the nitrogen gas can be, for example, 1 to 20 L / min, and specifically, 10 L / min, and within this range there is an advantage that the conversion rate to the lithium compound is high.

[0372] The above heat treatment can be carried out, for example, at 550 to 750 ℃, and specifically at 630 ℃, and within this range, there is an advantage that the cathode material is sufficiently reduced.

[0373] The rate of temperature increase until reaching the above heat treatment temperature can be, for example, 1 to 20 ℃ / min, specifically 3 ℃ / min, and within this range, it is possible to implement it without putting strain on the heat treatment equipment and has the advantage of not causing thermal shock to the cathode material.

[0374]

[0375] The above heat treatment can be performed for, for example, 0.5 to 5.5 hours, and specifically for 5 hours, and within this range, there is an advantage that the cathode material is sufficiently reduced.

[0376] The above heat treatment can be carried out, for example, at atmospheric pressure, and in this case, there is an advantage of a safe process and reduced production costs.

[0377] The above heat treatment can preferably be performed using a rotary kiln, in which case continuous processing is possible, productivity is excellent, and the reduction reaction can be promoted, which has the advantage of recovering high-purity lithium at a high yield.

[0378] After the above heat treatment, it may be cooled slowly or rapidly in the atmosphere, for example.

[0379] By crushing the heat-treated material obtained above to obtain heat-treated cathode material powder, the specific surface area of ​​the heat-treated material is increased, making it easy to leach with water, which has the advantage of recovering high-purity lithium at a high yield.

[0380] The cathode material powder crushed after the above heat treatment may have a particle size of, for example, 0.5 to 100 μm, and specifically, 10 to 15 μm, and within this range, lithium is easily leached out, which has the advantage of recovering high-purity lithium at a high yield.

[0381] In this description, the particle size can be measured using a measurement method commonly used in the technical field to which the present invention belongs, for example, by using a laser diffraction method. Specifically, after dispersing particles of the positive electrode active material in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device such as Microtrac S3500, and ultrasound of about 28 kHz is irradiated at an output of 60 W, and the average particle size (D50) at 50% of the particle diameter distribution in the measuring device can be calculated.

[0382]

[0383] For example, the above crushing can be performed using a milling machine, and specifically, a roll press can be used; in this case, there is an advantage of crushing the material uniformly.

[0384] The above crushing may be, for example, dry crushing, and in this case, there is an advantage of crushing the material uniformly and increasing the specific surface area of ​​the material.

[0385]

[0386] Next, the heat-treated cathode material powder is leached with water to obtain a leaching solution in which the lithium component is dissolved and a leaching residue, and these are separated to obtain a leaching solution (step S30).

[0387] Here, by leaching the heat-treated cathode powder with water, high-purity lithium compounds are recovered with fewer impurities such as Ni, Co, and Mn in the leaching solution compared to leaching using acid; furthermore, since no acid is used, wastewater treatment is unnecessary, which reduces production costs and offers the advantage of being environmentally friendly.

[0388] The above heat-treated cathode material powder and water can be mixed, for example, at a solid-liquid ratio of 1 g / 20 mL to 1 g / 40 mL, and specifically, at 1 g / 30 mL. Within this range, sufficient leaching of lithium occurs from the heat-treated cathode material powder, so that a leaching solution can be obtained in which the lithium component is dissolved at a high concentration and impurities are reduced.

[0389] The above water may be, for example, distilled water or deionized water, and specifically, distilled water, in which case there is an advantage of reducing impurities in the leachate.

[0390]

[0391] The above leaching can be performed by adding water to the heat-treated anode powder and stirring with a stirrer at room temperature.

[0392] The above stirring can be performed at 300 to 700 rpm, for example, and specifically at 500 rpm, and within this range, there is an advantage of promoting the leaching of lithium components from the heat-treated cathode powder.

[0393] The above stirring can be carried out for, for example, 0.5 hours or more, specifically for 1 hour, and within this range, lithium components are sufficiently leached from the heat-treated cathode powder, which has the advantage of obtaining lithium with a high recovery rate.

[0394] The above water may be neutral water, for example, and specifically distilled water; in this case, impurities in the leachate containing dissolved lithium components are reduced, and since acid is not used, there is an environmentally friendly advantage.

[0395] The above leaching is performed with water, which has the advantage of easily recovering high-purity lithium compounds because the leaching solution in which the lithium component is dissolved has a low content of impurities such as Ni, Co, and Mn.

[0396] The separation of the leachate and leachate residue obtained by the above leaching can be achieved by filtration, for example, and specifically by vacuum filtration. In this case, the leachate and leachate residue can be easily separated through a simple process without the use of acid, thereby reducing process costs and offering environmentally friendly advantages.

[0397] Through the above separation, a leachate containing dissolved lithium components is obtained.

[0398]

[0399] Next, the obtained leaching solution is fed into a flow capacitive deionization device to purify the lithium component (step S40).

[0400] The above-described flow-capacitance type deionization device comprises, for example, a lithium leaching solution circulation tank; an anion adsorption unit including a negative film flow electrode circulation tank, a current collector, and an anion exchange membrane; a cation adsorption unit including a cation exchange membrane, a current collector, and a positive film flow electrode circulation tank; a cation desorption unit including a current collector and a cation exchange membrane; and a cation collection unit including a deionized water circulation tank, an anion exchange membrane, a current collector, and a negative film flow electrode circulation tank.

[0401] The step (step S40) of purifying the obtained leaching solution in a flow capacitive deionization device may include, for example, a step of passing the leaching solution in which a lithium component is dissolved between an anion adsorption unit including a negative film flow electrode and a cation adsorption unit including an amphoteric film flow electrode to adsorb lithium cations onto the amphoteric film flow electrode; a step of passing the amphoteric film flow electrode on which lithium cations are adsorbed between a current collector and a cation exchange membrane to desorb lithium cations from the amphoteric film flow electrode; and a step of collecting the desorbed lithium cations as deionized water.

[0402] The lithium component purified through the above-mentioned flow-capacitance deionization device has high lithium purity and contains only trace amounts of impurities.

[0403]

[0404] Next, the purified lithium component is obtained as a lithium crystalline salt (step S50).

[0405] The above-mentioned purified lithium component may exist in the form of a concentrate containing the purified lithium component, for example.

[0406] In the present invention, the step of obtaining a lithium crystalline salt from a purified lithium component may utilize methods commonly used in the technical field to which the present invention belongs. For example, lithium carbonate may be recovered by introducing a carbonate or carbon dioxide gas into the purified lithium component. Preferably, Na2CO3 or CO2 may be introduced, and more preferably, CO2 may be introduced.

[0407] The concentrate containing the above-mentioned purified lithium component may, for example, have a pH of 11 or higher, and in this case, there is an advantage of easily carbonating the lithium by introducing CO2 to recover high-purity lithium.

[0408] For example, carbon dioxide can be introduced into the concentrate containing the above-mentioned purified lithium component, and specifically, if CO2 is introduced, the lithium is ionized into the forms of Li2CO3 and LiHCO3. Here, CO2 is introduced in an amount greater than that which can convert LiOH in the lithium concentrate into Li2CO3, and in this case, there is an advantage that the lithium component is carbonated and recovered as lithium carbonate.

[0409]

[0410] The lithium compounds ionized in the form of Li2CO3 and LiHCO3 are heated, for example, at 65 to 95 ℃ for 40 to 80 minutes, and specifically, at 80 ℃ for 60 minutes, to obtain a precipitate precipitated in the form of Li2CO3 and a filtrate.

[0411] Once the above precipitation is complete, the precipitate in the form of Li2CO3 and the filtrate are separated by vacuum filtration. Since the filtrate contains a small amount of lithium, it is fed into the flow capacitive deionization device of step S40 to be recirculated.

[0412] The above Li2CO3-type precipitate is washed with water at 70 to 90°C, for example, 80°C, and then dried to obtain the final Li2CO3 powder.

[0413]

[0414] In addition, referring to FIG. 3, a lithium-ion battery positive electrode is first crushed and ground to prepare a positive electrode material powder (step S10).

[0415] The positive active material in the above positive material powder may be an NCM-based lithium complex transition metal oxide or a lithium iron phosphate compound.

[0416] Since the above step S10 is identical to the step S10 of FIG. 2 described above, it is omitted here.

[0417]

[0418] Next, a leachate is obtained from the obtained cathode material powder (step S20).

[0419] Step S20 above involves introducing the obtained cathode material powder into a mixture of an acidic solution and an oxidizing agent and leaching to obtain a leaching solution in which lithium is dissolved and a leaching residue, and separating them to obtain the leaching solution.

[0420] The above acidic solution may be a solution containing one or more selected from the group consisting of sulfuric acid, hydrochloric acid, hypochlorous acid, nitric acid, carbonic acid, acetic acid, and oxalic acid, for example, a solution containing hydrochloric acid or sulfuric acid as a specific example, and in one embodiment, an aqueous hydrochloric acid solution or an aqueous sulfuric acid solution, in which case there is an advantage of selectively leaching lithium components.

[0421] The acidic solution may have an acid concentration of, for example, 0.1 to 1.5 molar concentrations (mol / L), and specifically, 0.6 molar concentrations to 1.0 molar concentrations. In this case, using a low concentration of acid reduces wastewater generation and has the advantage of selectively leaching lithium components.

[0422] The above acidic solution may contain, for example, 0.5 to 1.5 moles of acid per 1 mole of positive active material in the positive material powder, and specifically, 1.1 moles, and in this case, there is an advantage that all elements in the positive material are easily dissolved with a small amount of acid.

[0423] The above oxidizing agent may be included in an amount of, for example, 0.5 to 2.3 moles per mole of the positive active material in the positive material powder, and specifically, 2.1 moles. In this case, there is an advantage of selectively dissolving the lithium component in the positive material powder and precipitating the metallic component other than lithium to easily separate them.

[0424] The above oxidizing agent may include, for example, one or more selected from the group consisting of hydrogen peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, oxygen, and air, and specifically, hydrogen peroxide may be used. In this case, there is an advantage of selectively dissolving the lithium component in the cathode material powder and precipitating the metallic component other than lithium to easily separate them.

[0425]

[0426] The above step S20 can be carried out at room temperature, for example, and in this case, there is an advantage that the lithium in the cathode material powder dissolves and metal components other than lithium precipitate.

[0427] The above step S20 can be carried out under stirring, for example, at a stirring speed of 300 to 700 rpm, specifically 500 rpm, and within this range, there is an advantage that lithium in the cathode powder is dissolved and metal components other than lithium are precipitated.

[0428] In step S20 above, stirring can be performed for, for example, 0.5 hours or more, specifically for 2 hours, and within this range, there is an advantage that lithium in the cathode powder is dissolved and metal components other than lithium are precipitated.

[0429] The separation of the above lithium-dissolved leaching solution and the leaching residue can be achieved, for example, by filtration; specifically, the leaching solution can be obtained by separation using vacuum filtration. In this case, the leaching solution and the leaching residue can be easily separated through a simple process, reducing process costs and offering environmentally friendly advantages.

[0430]

[0431] Next, the obtained leachate is filtered through a nanofiltration membrane (step S30).

[0432] The above step S30 has the advantage of removing polyvalent cations such as Fe, Al, Ni, Co, or Mn in addition to lithium from the obtained leaching solution, thereby recovering high-purity lithium.

[0433] The above nanofiltration membrane may, for example, have a fractional molecular weight of 100 to 1,000 Da, preferably 200 to 700 Da, more preferably 200 to 500 Da, and in this case, there is an advantage that the purity of lithium is further improved by removing polyvalent cations such as Fe, Al, Ni, Co, or Mn.

[0434]

[0435] Next, the filtered leachate is fed into a flow capacitive deionization device to purify the lithium component (step S40).

[0436] Since the above step S40 is identical to the step S40 of FIG. 2 described above, it is omitted here.

[0437] The lithium component purified through the above-mentioned flow-capacitance deionization device has high lithium purity and contains only trace amounts of impurities.

[0438]

[0439] Next, the purified lithium component is obtained as a lithium crystalline salt (step S50).

[0440] Since the above step S50 is identical to the step S50 of FIG. 2 described above, it is omitted here.

[0441]

[0442] In addition, referring to FIG. 4, a lithium-ion battery positive electrode is first crushed and ground to prepare a positive electrode material powder (step S10).

[0443] The positive active material in the above positive material powder may be an NCM-based lithium complex transition metal oxide or a lithium iron phosphate compound.

[0444] Since the above step S10 is identical to the step S10 of FIG. 2 described above, it is omitted here.

[0445]

[0446] Next, a leachate is obtained from the obtained cathode material powder (step S20).

[0447] Since the above step S20 is identical to the step S20 of FIG. 3 described above, it is omitted here.

[0448]

[0449] Next, lithium hydroxide (LiOH) or a basic compound is added to the obtained leaching solution as an impurity removal agent to remove impurities (step S30).

[0450] The above step S30 has the advantage of recovering high-purity lithium, as high-purity lithium can be easily removed by precipitating polyvalent cations such as Fe, Al, Ni, Co, or Mn, by adding, for example, lithium hydroxide (LiOH) or a basic compound to the obtained leachate to raise the pH of the leachate.

[0451] The above basic compound may be, for example, a metal hydroxide, a metal carbonate, or a mixture thereof, and specifically, NaOH. In this case, the pH of the leaching solution is raised so that polyvalent cations such as Fe, Al, Ni, Co, or Mn can be easily removed by precipitating them, which has the advantage of recovering high-purity lithium.

[0452] The above metal hydroxide may preferably be sodium hydroxide, potassium hydroxide, or a mixture thereof. In this case, the pH of the leaching solution is raised so that polyvalent cations such as Fe, Al, Ni, Co, or Mn can be easily removed by precipitating them, which has the advantage of recovering high-purity lithium.

[0453] The above metal carbonate may preferably be sodium carbonate, potassium carbonate, or a mixture thereof, and in this case, the pH of the leaching solution is raised so that polyvalent cations such as Fe, Al, Ni, Co, or Mn can be easily removed by precipitating them, thereby having the advantage of recovering high-purity lithium.

[0454] The above lithium hydroxide (LiOH) may be, for example, 0.05 to 0.3 moles per 1 mole of positive active material in the leaching solution, and as a specific example, 0.17 moles may be added. In this case, the pH of the leaching solution is increased, and there is an advantage that polyvalent cations such as Fe, Al, Ni, Co, or Mn are precipitated and easily removed.

[0455] The above basic compound can be added, for example, in an amount of 0.05 to 0.3 moles per mole of positive active material in the leaching solution, and specifically in an amount of 0.17 moles. In this case, the pH of the leaching solution is increased, and there is an advantage that polyvalent cations such as Fe, Al, Ni, Co, or Mn are precipitated and easily removed.

[0456] After adding lithium hydroxide (LiOH) or a basic compound to the above leaching solution, the pH may be, for example, pH 3 or higher, and specifically, pH 4.3 or higher, and within this range, there is an advantage that polyvalent cations such as Fe, Al, Ni, Co, or Mn, which are impurities, are precipitated and easily removed.

[0457]

[0458] Next, the lithium component of the leaching solution from which impurities have been removed is purified through a flow capacitive deionization device (step S40).

[0459] Since the above step S40 is identical to the step S40 of FIG. 2 described above, it is omitted here.

[0460] The lithium component purified through the above-mentioned flow-capacitance deionization device has high lithium purity and contains only trace amounts of impurities.

[0461]

[0462] Next, the purified lithium component is obtained as a lithium crystalline salt (step S50).

[0463] Since the above step S50 is identical to the step S50 of FIG. 2 described above, it is omitted here.

[0464]

[0465] In addition, referring to FIG. 5, a lithium-ion battery positive electrode is first crushed and ground to prepare a positive electrode material powder (step S10).

[0466] The positive active material in the above positive material powder may preferably be an NCM-based lithium complex transition metal oxide or a lithium iron phosphate compound.

[0467] Since the above step S10 is identical to the step S10 of FIG. 2 described above, it is omitted here.

[0468]

[0469] Next, a leachate is obtained from the obtained cathode material powder (step S20).

[0470] Since the above step S20 is identical to the step S20 of FIG. 3 described above, it is omitted here.

[0471]

[0472] Next, the remaining liquid after obtaining a lithium component purified by an impurity removal agent as a lithium crystal salt is added to the obtained leaching solution to remove impurities (step S30).

[0473] In the above step S30, the filtrate is the liquid remaining after separating the purified lithium component obtained through a flow capacitive deionization device by precipitating it as a lithium crystal salt, and the filtrate contains a lithium component.

[0474] The above liquid can be added in an amount such that, for example, 0.2 to 0.8 moles, or specifically 0.5 moles of lithium, are contained in 1 mole of lithium in the purified lithium component. In this case, the pH of the leaching solution is raised so that polyvalent cations such as Fe, Al, Ni, Co, or Mn can be precipitated and easily removed, which has the advantage of recovering high-purity lithium.

[0475] After adding the filtrate to the above-mentioned leachate, the pH may be, for example, pH 3 or higher, and specifically, pH 4.3 or higher, and within this range, polyvalent cations such as Fe, Al, Ni, Co, or Mn are precipitated and easily removed, which is an advantage.

[0476]

[0477] Next, the leaching solution from which the above impurities have been removed is introduced into a flow capacitive deionization device to purify the lithium component (step S40).

[0478] Since the above step S40 is identical to the step S40 of FIG. 2 described above, it is omitted here.

[0479] The above-mentioned refined lithium component has high lithium purity and contains only trace amounts of impurities.

[0480]

[0481] Next, the purified lithium component is obtained as a lithium crystalline salt (step S50).

[0482] Since the above step S50 is identical to the step S50 of FIG. 2 described above, it is omitted here.

[0483]

[0484] In addition, referring to FIG. 6, a lithium-ion battery positive electrode is first crushed and ground to prepare a positive electrode material powder (step S10).

[0485] The positive active material in the above positive material powder may preferably be an NCM-based lithium complex transition metal oxide or a lithium iron phosphate compound.

[0486] Since the above step S10 is identical to the step S10 of FIG. 2 described above, it is omitted here.

[0487] A leaching solution can be obtained from a portion of the cathode material powder obtained by crushing and grinding as described above, and the remainder of the cathode material powder can be used as an impurity removal agent.

[0488]

[0489] Next, a leachate is obtained from the obtained cathode material powder (step S20).

[0490] Since the above step S20 is identical to the step S20 of FIG. 3 described above, it is omitted here.

[0491]

[0492] Next, the cathode material powder is added to the obtained leaching solution as an impurity removal agent to remove impurities (step S30).

[0493] In step S30 above, the cathode material powder is obtained by crushing and grinding the lithium-ion battery cathode in step S10 above, and contains a large amount of lithium.

[0494] The above-mentioned cathode material powder can be added in such a way that, for example, 0.1 to 0.7 moles, or specifically 0.21 moles of lithium, are contained in 1 mole of lithium in the lithium leaching solution. In this case, the pH of the leaching solution is raised so that impurities such as Fe, Al, Ni, Co, or Mn can be precipitated and easily removed, which has the advantage of recovering high-purity lithium.

[0495] After adding the filtrate to the above-mentioned leachate, the pH may be, for example, pH 3 or higher, specifically, pH 4.3 or higher, and within this range, polyvalent cations such as Fe, Al, Ni, Co, or Mn are precipitated and easily removed, which is an advantage.

[0496]

[0497] Next, the lithium component is purified by introducing it into a flow capacitive deionization device (step S40).

[0498] Since the above step S40 is identical to the step S40 of FIG. 2 described above, it is omitted here.

[0499] The lithium component purified through the above-mentioned flow-capacitance deionization device has high lithium purity and contains only trace amounts of impurities.

[0500]

[0501] Next, the purified lithium component is obtained as a lithium crystalline salt (step S50).

[0502] Since the above step S50 is identical to the step S50 of FIG. 2 described above, it is omitted here.

[0503]

[0504] Hereinafter, preferred embodiments are presented to aid in understanding the present invention; however, the following embodiments are merely illustrative of the invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and spirit of the invention, and that such variations and modifications fall within the scope of the appended claims.

[0505]

[0506] [Example I: Purification of lithium components using a flow-capacitance deionization device]

[0507] * Flow-capacitive deionization device: A flow-capacitive deionization device as shown in FIG. 7 below was used. Specifically, it included a lithium leaching solution circulation tank (11); an anion adsorption unit including a negative film flow electrode circulation tank (12), a current collector (100), and an anion exchange membrane (200); a cation adsorption unit including a cation exchange membrane (300), a current collector, and a positive film flow electrode circulation tank (13); a cation desorption unit including a current collector (100) and a cation exchange membrane (300); and a cation collection unit including a deionized water circulation tank (15), an anion exchange membrane (200), a current collector (100), and a negative film flow electrode circulation tank (14). The above cation exchange membrane (300) and anion exchange membrane (200) are pore-filled ion exchange membranes from TAK, with an electrolyte filled in a polyolefin-based support and a thickness of 60 μm, the current collector (100) is graphite, the active material in the flow electrode is activated carbon, the conductive additive is carbon black, and the solvent is water. The current collector of the above flow capacitive deionization device was connected to a power supply (Potentiostat) and electricity was applied under a constant current condition of 1.5 A, and the flow electrode concentration was 13 wt%, the positive membrane flow electrode, the negative membrane flow electrode, the lithium leaching solution, and the deionized water were operated at a speed of 40 mL / min.

[0508] * A method for purifying a lithium component using a flow capacitive deionization device: comprising the steps of: passing a leaching solution in which a lithium component is dissolved between an anion adsorption unit including a negative film flow electrode and a cation adsorption unit including a positive film flow electrode to adsorb lithium cations onto the positive film flow electrode; passing the positive film flow electrode on which lithium cations are adsorbed between a current collector and a cation exchange membrane to desorb lithium cations from the positive film flow electrode; and collecting the desorbed lithium cations as deionized water.

[0509] * Content of Li, Ni, Co, Mn, Fe, P, and Al (ppm): Measured via ICP analysis. Specifically, 0.2 g of a solution containing Li, Ni, Co, Mn, Fe, P, or Al was taken, placed in a conical tube, and weighed accurately. Then, 0.1 ml of nitric acid with a concentration of 70 wt% was added, followed by the addition of 500 µl of 1000 mg / kg internal STD (Sc), and the solution was diluted with ultrapure water to a volume of 50 ml. The content of Li, Ni, Co, Mn, Fe, P, and Al was then measured via ICP analysis.

[0510] * Lithium purity (wt%): 0.1 g of the sample was taken, placed in a conical tube, and weighed accurately. Then, 1.0 ml of nitric acid with a concentration of 70 wt% was added to dissolve it. After the sample was decomposed, 0.1 ml of internal STD (Sc, 1000 ppm) was added and diluted with ultrapure water to a total volume of 10 ml. The content of Li, Ni, Co, Mn, Fe, P, and Al was measured by ICP-OES analysis. The purity of lithium was calculated from the measured content using the following Equation 1.

[0511] [Mathematical Formula 1]

[0512] Lithium Purity (weight%) = 100 weight% - Total of Components Excluding Lithium (weight%)

[0513]

[0514] Example 1

[0515] The discarded anode scrap (current collector: aluminum foil, anode active material: NCMA-based lithium composite transition metal oxide) after anode plate stamping was crushed and ground to obtain anode material in powder form. The crushing was performed using a shredder and the grinding was performed using a solid mixer, after which the anode material powder was obtained by sieving using a 325 mesh sieve.

[0516] 37 g of graphite anode material was added as a carbon-based reducing agent to 300 g of the above-mentioned obtained cathode material powder, and the product was heat-treated at 630 ℃ for 5 hours in an N2 atmosphere to obtain a heat-treated product. Here, the temperature rise rate until reaching the heat treatment temperature was 3 ℃ / min, and N2 was supplied at 10 L / min. At this time, 1 mole of carbon-based reducing agent was added for every 1 mole of cathode active material in the cathode material powder. Here, the number of moles of cathode active material in the cathode material powder can be calculated by assuming the mass of the cathode material powder to be the mass of the cathode active material.

[0517] The above heat-treated product was crushed and ground to obtain heat-treated cathode material powder.

[0518] The heat-treated cathode material powder was placed in distilled water at room temperature and stirred at a stirring speed of 500 rpm for 60 minutes to obtain a leaching solution containing dissolved lithium and a leaching residue. At this time, the solid-to-liquid ratio of the heat-treated cathode material powder to the distilled water was 1 g / 30 mL.

[0519] The above leachate and leachate residue were separated by vacuum filtration to obtain the leachate, and the components of the obtained leachate were measured by ICP analysis and are shown in Table 1 below.

[0520] The lithium component of the above leaching solution was purified through a flow capacitive deionization device to obtain a lithium concentrate, and the components of the obtained lithium concentrate were measured by ICP analysis and are shown in Table 1 below.

[0521] CO2 was added to the obtained lithium concentrate to carbonate the lithium component in the concentrate, and then heated at 80°C for 60 minutes to precipitate it as Li2CO3.

[0522] The above-mentioned precipitated Li2CO3 was separated by vacuum filtration, and the obtained Li2CO3 was washed with water at 80°C and then dried.

[0523] The content of each component of the Li2CO3 powder obtained after drying was measured by ICP analysis and is shown in Table 2 below, and the results of XRD analysis are shown in Figure 11 below. For reference, the Li content was not measured because the reliability of the quantitative value was low due to the high Li content, which is the main component of lithium carbonate.

[0524]

[0525] As a result of measuring the purity of lithium from the content of each component measured by ICP analysis, the purity of lithium was 99 wt% or higher.

[0526]

[0527]

[0528] The above ppm means mg / kg.

[0529]

[0530] As shown in Table 1 above, it was confirmed that during the purification process of lithium components using a flow capacitive deionization device, the lithium content increased significantly, while Ni, Co, Mn, Fe, Al, and Cu components were not detected, and the F component also decreased significantly. Here, the increase in the content of 13 types of etc (other) components, such as Na, K, Ca, S, and P, is due to the inclusion of elements originating from activated carbon during the purification process of lithium components using the flow capacitive deionization device. The 13 types of etc (other) components can be easily removed by washing during the subsequent lithium crystallization stage.

[0531]

[0532]

[0533] The above ppm means mg / kg.

[0534]

[0535] As shown in Table 2 above, it was confirmed that high-purity lithium was recovered from the final obtained lithium carbonate powder, as Ni, Co, Mn, Fe, Al, and Cu components were not detected, and only small amounts of 13 other components such as Na, K, Ca, S, and P, as well as F, were detected.

[0536] In addition, as shown in Figure 11 below, XRD measurement results confirmed that it was consistent with the crystalline phase of lithium carbonate.

[0537]

[0538] Example 2

[0539] The anode scrap (current collector: aluminum foil, anode active material: LFP-based lithium iron phosphate compound) discarded after anode plate stamping was crushed and ground to obtain anode material in powder form.

[0540] 500 g of the above cathode material powder was added to a mixed solution of 4300 mL of an aqueous hydrochloric acid solution with a concentration of 0.8 molar (mol / L) and 700 mL of an aqueous hydrogen peroxide solution with a concentration of 30-32 wt%, and dissolved at room temperature under stirring to obtain a leaching solution containing dissolved lithium and a leaching residue. At this time, for every 1 mol of cathode active material in the cathode material powder, the hydrochloric acid was 1.1 mol and the hydrogen peroxide was 2.1 mol.

[0541] The above-mentioned leachate and leachate residue were separated by vacuum filtration to obtain the leachate, and the content of Li, Fe, P, and Al was measured through ICP analysis and is shown in Table 3 below.

[0542] The above leachate was filtered through a nanofiltration membrane to remove polyvalent ions such as Fe and Al from the leachate, and the content of Li, Fe, P, and Al was measured through ICP analysis and is shown in Table 3 below.

[0543] The lithium component of the leaching solution from which the above-mentioned polyvalent ions had been removed was purified through a flow capacitive deionization device to obtain a lithium concentrate.

[0544] The above-mentioned lithium concentrate was carbonated by adding CO2, and then heated at 80°C for 60 minutes to precipitate as Li2CO3.

[0545] The above-mentioned precipitated Li2CO3 was separated by vacuum filtration, and the obtained Li2CO3 was washed with water at 80°C and then dried.

[0546] The purity of the Li2CO3 powder obtained after drying was calculated through ICP analysis, and the purity of the lithium was 99 wt% or higher.

[0547]

[0548]

[0549] The above ppm means mg / kg.

[0550]

[0551] As shown in Table 3 above, it was confirmed that Fe and Al components were not detected and P components were significantly reduced through the process of filtering the lithium leaching solution with a nanofiltration membrane.

[0552]

[0553] Example 3

[0554] The anode scrap (current collector: aluminum foil, anode active material: LFP-based lithium iron phosphate compound) discarded after anode plate stamping was crushed and ground to obtain anode material in powder form.

[0555] 500 g of the above cathode material powder was added to a mixed solution of 4300 ml of an aqueous hydrochloric acid solution with a concentration of 0.8 mol (mol / L) and 700 ml of an aqueous hydrogen peroxide solution with a concentration of 30-32 wt%, and dissolved at room temperature under stirring to obtain a leaching solution containing dissolved lithium and a leaching residue. At this time, for every 1 mol of cathode active material in the cathode material powder, the hydrochloric acid was 1.1 mol and the hydrogen peroxide was 2.1 mol.

[0556] The above-mentioned leachate and leachate residue were separated by vacuum filtration to obtain the leachate.

[0557] LiOH was added to the above leachate to raise the pH to 4.3 or higher, thereby causing polyvalent ions such as Fe and Al to precipitate, and these were separated by vacuum filtration to obtain a leachate from which polyvalent ions were removed. At this time, LiOH was added in an amount of 0.17 moles per 1 mole of Li in the leachate.

[0558] The lithium component of the leaching solution from which the above-mentioned polyvalent ions had been removed was purified through a flow capacitive deionization device to obtain a lithium concentrate.

[0559] CO2 was added to the obtained lithium concentrate to carbonate the lithium component in the concentrate, and then heated at 80°C for 60 minutes to precipitate it as Li2CO3.

[0560] The above-mentioned precipitated Li2CO3 was separated by vacuum filtration, and the obtained Li2CO3 was washed with water at 80°C and then dried.

[0561] As a result of measuring the purity of the Li2CO3 powder obtained after drying through ICP analysis, the purity of lithium was 99 wt% or higher.

[0562]

[0563] Comparative Example 1

[0564] The procedure was carried out in the same manner as Example 1, except that the leaching solution was not introduced into a flow-capacitive deionization device, but a precipitate was obtained through vacuum evaporation and dried to obtain Li2CO3 powder. The obtained Li2CO3 powder was analyzed by XRD and is shown in Fig. 12 below.

[0565]

[0566] As shown in Fig. 12 below, in Comparative Example 1, a LiF peak was observed in addition to Li2CO3, and the LiF content measured by quantitative analysis based on peak intensity was 2 wt%, from which the purity of lithium was calculated to be 97.6 wt%.

[0567]

[0568] [Explanation of the symbol]

[0569] 10: Adsorption part

[0570] 11: Li leaching solution circulation tank

[0571] 12: Negative membrane flow electrode circulating tank

[0572] 13: Amniotic membrane flow electrode circulation tank

[0573] 14: Negative film flow electrode circulating tank

[0574] 15: Deionized water circulation tank

[0575] 20: Detachable part

[0576] 100: Whole house

[0577] 200: Anion Exchange Membrane (AEM)

[0578] 300: Cation Exchange Membrane (CEM)

[0579] 400: Spacer

[0580] 500: Pump

Claims

The method is characterized by comprising the steps of obtaining a leaching solution in which a lithium component is dissolved from a cathode material powder, and introducing the leaching solution into a flow capacitive deionization device to purify the lithium component. Method for recovering lithium. A step of passing a leachate containing dissolved lithium components between an anion adsorption section including a negative film flow electrode and a cation adsorption section including an amniotic film flow electrode to adsorb lithium cations onto the amniotic film flow electrode; A step of desorbing lithium cations from an amniotic flow electrode by passing the amniotic flow electrode, on which lithium cations are adsorbed, between a current collector and a cation exchange membrane, and Characterized by including the step of collecting detached lithium cations in deionized water. Method for recovering lithium. (a) A step of obtaining cathode material powder by crushing and / or grinding the lithium-ion battery cathode; (b) a step of adding a leaching solvent to the cathode material powder to obtain a leaching solution in which the lithium component is dissolved; (c) a step of purifying the lithium component of the leaching solution through a flow capacitive deionization device; and (d) a step of obtaining a purified lithium component as a lithium crystal salt; characterized by including Method for recovering lithium. In paragraph 3, The method is characterized by heat-treating the anode material powder obtained in step (a) with a carbon-containing reducing agent to obtain a heat-treated product, crushing and / or grinding the heat-treated product, and then introducing it into step (b). Method for recovering lithium. In paragraph 4, The above heat treatment is characterized by being carried out at a temperature of 550 to 750 ℃ ​​under a reducing gas or an inert gas. Method for recovering lithium. In paragraph 4, The above carbon-containing reducing agent is characterized by being used in an amount of 0.3 to 3 moles per mole of cathode active material in the cathode material powder. Method for recovering lithium. In paragraph 4, The above carbon-containing reducing agent is characterized by being an organic material containing carbon, an inorganic material containing carbon, a carbon-based cathode material, or a mixture of two or more of these. Method for recovering lithium. In paragraph 3, The above step (b) is characterized by leaching the cathode material powder obtained in step (a) with water to obtain a leaching solution in which lithium is dissolved and a leaching residue, and separating them to collect the leaching solution. Method for recovering lithium. In paragraph 3, The above step (b) is characterized by adding the cathode material powder obtained in step (a) to a mixture of an acidic solution and an oxidizing agent to obtain a leaching solution in which lithium is dissolved and a leaching residue, and separating them to collect the leaching solution. Method for recovering lithium. In Paragraph 9, In step (b) above, the acidic solution is characterized by having an acid concentration of 0.1 to 1.5 (mol / L). Method for recovering lithium. In Paragraph 9, The acidic solution is characterized in that, in step (b) above, it is added in an amount of 0.1 to 1.5 moles of acid per 1 mole of positive active material in the positive material powder. Method for recovering lithium. In Paragraph 9, The oxidizing agent is characterized in that, in step (b) above, it is added in an amount of 0.5 to 2.3 moles per mole of anode active material in the anode powder. Method for recovering lithium. In Paragraph 9, The oxidizing agent in step (b) above is characterized by comprising one or more selected from the group consisting of hydrogen peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, oxygen, and air. Method for recovering lithium. In paragraph 3, The leaching solution obtained in step (b) above is characterized by being introduced into step (c) after performing an impurity removal step (b'). Method for recovering lithium. In Paragraph 14, The above impurity removal step (b') is characterized by being a step of filtering the leachate through a nanofiltration membrane. Method for recovering lithium. In Paragraph 14, The above impurity removal step (b') is characterized by adding one or more impurity removal agents selected from the group consisting of lithium hydroxide (LiOH); a basic compound; cathode material powder; and the filtrate remaining after obtaining a lithium crystal salt from a purified lithium component to the leaching solution. Method for recovering lithium. In paragraph 3, In the above step (c), the step of purifying the lithium component is characterized by being filtered together with the purification. Method for recovering lithium. In paragraph 3, In step (c) above, the leaching solution introduced into the flow capacitive deionization device is characterized by having a total metal component excluding lithium of 1 weight% or less. Method for recovering lithium. In paragraph 3, In the above step (c), the flow capacitive deionization device is characterized by comprising: a lithium leaching solution circulation tank; an anion adsorption unit including a negative film flow electrode circulation tank, a current collector, and an anion exchange membrane; a cation adsorption unit including a cation exchange membrane, a current collector, and an anode flow electrode circulation tank; a cation desorption unit including a current collector and a cation exchange membrane; and a cation collection unit including a deionized water circulation tank, an anion exchange membrane, a current collector, and a negative film flow electrode circulation tank. Method for recovering lithium. In Paragraph 19, In the above step (c), the flow capacitive deionization device passes a leaching solution in which a lithium component is dissolved between an anion adsorption part including a negative film flow electrode and a cation adsorption part including an amniotic film flow electrode to adsorb lithium cations onto the amniotic film flow electrode; A step of desorbing lithium cations from an amniotic flow electrode by passing the amniotic flow electrode, on which lithium cations are adsorbed, between a current collector and a cation exchange membrane; and Characterized by including the step of collecting detached lithium cations in deionized water. Method for recovering lithium. In paragraph 20, The above-described flow capacitive deionization device is characterized by comprising: a step of passing a leaching solution in which a lithium component is dissolved between a cation adsorption part including a positive film flow electrode and an anion adsorption part including a negative film flow electrode to adsorb anions onto the negative film flow electrode; a step of passing the negative film flow electrode on which anions are adsorbed between a current collector and an anion exchange membrane to desorb anions from the negative film flow electrode; and a step of collecting the desorbed anions as deionized water. Method for recovering lithium. In Paragraph 19, The above-mentioned positive and negative flow electrodes are each characterized by comprising an active material, a conductive additive, and a solvent. Method for recovering lithium. In Paragraph 22, The above active material is characterized by comprising one or more selected from the group consisting of activated carbon, carbon beads, mesoporous carbon, carbon nanotubes, graphene, carbon black, activated carbon fiber, and MnO2. Method for recovering lithium. In Paragraph 22, The conductive additive comprises one or more selected from the group consisting of carbon black, carbon nanotubes, graphene, and reduced graphene oxide (rGO), and is characterized by not being identical to the active material. Method for recovering lithium. In Paragraph 22, The above solvent is characterized as being a sodium chloride (NaCl) solution, deionized water, or distilled water. Method for recovering lithium. In paragraph 3, The lithium crystalline salt obtained in step (d) above is characterized by comprising one or more selected from the group consisting of LiOH, Li2CO3, LiCl, Li2SO4, and LiNO3. Method for recovering lithium. In paragraph 3, The above step (d) is characterized by being a step of carbonating the purified lithium component to obtain lithium carbonate. Method for recovering lithium. In paragraph 3, The lithium crystalline salt obtained in step (d) above is characterized by having a lithium purity of 99 weight% or more. Method for recovering lithium. In paragraph 3, The lithium component purified in step (d) above is converted into a lithium crystal salt, and the remaining liquid is fed into a flow capacitive deionization device for reuse. Method for recovering lithium. In paragraph 3, The above-mentioned cathode material is characterized by comprising one or more selected from the group consisting of lithium cobalt oxide; lithium manganese oxide; lithium iron phosphate compound; lithium nickel cobalt aluminum oxide; lithium nickel oxide; a nickel-manganese-based lithium composite metal oxide in which a portion of the nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn); and an NCM-based lithium composite transition metal oxide in which a portion of the nickel (Ni) in the lithium nickel oxide is substituted with manganese (Mn) and cobalt (Co). Method for recovering lithium. In paragraph 3, The above lithium-ion battery positive electrode is characterized as being a discarded lithium-ion battery positive electrode. Method for recovering lithium. Lithium leaching solution circulation tank; Anion adsorption unit comprising a negative film flow electrode circulation tank, a current collector, and an anion exchange membrane; A cation adsorption unit comprising a cation exchange membrane, a current collector, and a cation flow electrode circulation tank; A cation desorption unit comprising a current collector and a cation exchange membrane; and A cation collection unit comprising a deionized water circulation tank, an anion exchange membrane, a current collector, and a negative film flow electrode circulation tank; and Herein, the lithium cations contained in the lithium leaching solution are characterized by moving to the cation exchange membrane of the adsorption section and then to the cation flow electrode circulation tank, and then passing through the cation exchange membrane of the desorption section and being collected in the deionized water circulation tank of the collection section. Lithium recovery device.

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