WO2025170334A1 - Method for recovering iron phosphate battery material from used iron phosphate battery and method for disabling iron phosphate battery - Google Patents

Abstract

The present invention relates to a method for recovering an iron phosphate battery material, the method comprising: a step (S1) of inducing a chemical discharge by opening an outer pouch of a used iron phosphate battery in a solution; and a step (S2) of recovering a battery material from the solution after the chemical discharge. The method for recovering an iron phosphate battery material can recover the main materials from a used iron phosphate battery with high efficiency and speed at a low cost.

Description

Method for recovering iron phosphate battery materials from used iron phosphate batteries and method for disabling iron phosphate batteries

The present invention relates to a method for recovering iron phosphate battery materials from spent iron phosphate batteries and a method for disabling iron phosphate batteries. Specifically, the present invention relates to a method for recovering iron phosphate battery materials after chemically discharging a spent iron phosphate battery and a method for disabling iron phosphate batteries.

Lithium iron phosphate (LiFePO ₄ ), which has an olivine structure and is mainly used as a cathode active material for lithium secondary batteries, has the characteristics of long life and overcharge prevention due to high structural stability. In addition, lithium iron phosphate (LiFePO 4 ) is widely used as a cathode active material for lithium secondary batteries because it contains iron, which is abundant and inexpensive compared to other cathode active materials such as LiCoO ₂ , LiNi _x Co _{y Mn} 1 _{- xy} O ₂ , or LiNi _x Co y Al 1-xy O ₂ , making it easy to obtain raw materials and environmentally friendly due to its low toxicity. However, in the case of lithium secondary batteries that use lithium iron phosphate as a cathode active material, they are usually disposed of after about 10 years of use as the capacity of the battery decreases. Accordingly, interest in the treatment and recycling of spent lithium secondary batteries containing lithium iron phosphate as a cathode active material, i.e. spent iron phosphate batteries, is increasing, and various studies are being conducted on methods for recovering spent iron phosphate battery materials.

Existing recycling processes for used batteries can be broadly categorized into dry and wet processes. Dry processes involve placing the entire used battery in an electric furnace, eliminating the need for separate crushing and sorting. This process melts and separates valuable metals like cobalt and nickel, while other metals containing lithium are discharged as slag. In this high-temperature dry process, lithium either evaporates and is lost or remains in the slag. Recovering this lithium is challenging and requires high processing costs.

In the wet process, the cathode material from used batteries is crushed and sorted, then the lithium is extracted into a solution. The valuable metal is then separated from the solution through solvent extraction. The lithium is then manufactured into a metal or compound through processes such as electrowinning or crystallization. However, the wet process is complex and expensive, and the use of hazardous compounds, such as acids or alkaline solutions, to extract the lithium can cause environmental problems.

Meanwhile, a technology for recovering valuable metals from spent batteries without using hazardous compounds such as acid solutions has been devised (Patent Document 1). Specifically, a step of heat-treating an electrode recovered from a spent lithium-ion battery at 180 to 450 degrees to melt and remove the binder, and then obtaining a separated electrode active material, and recovering valuable metals through an electrolytic method (capacitive de-ionization (CDI) method) in an aqueous solution condition. However, in order to recover the electrode active material from the spent battery, a separate heat treatment process is required to melt and remove the binder of the spent battery, which incurs additional costs, and there is a problem that valuable metals including lithium contained in the cathode active material may be lost due to the high-temperature heat treatment.

Therefore, a technology for recovering iron phosphate battery materials with high efficiency, a fast process, and low cost is required in this technical field. The inventors of the present invention have completed the present invention after continuous research into a method for recovering iron phosphate battery materials to address the aforementioned problems in iron phosphate batteries using lithium iron phosphate as the cathode active material.

[Prior Art Literature]

[Patent Document]

(Patent Document 1) Republic of Korea Patent Publication No. 10-2403455

The present invention aims to recover major materials from used iron phosphate batteries with high efficiency, fast process, and low cost.

The purposes of the present invention are not limited to those mentioned above, and other purposes not mentioned will be clearly understood from the description below.

According to one aspect of the present invention, the present invention provides a method for recovering iron phosphate battery material.

In one specific example of the present invention, the method for recovering the iron phosphate battery material includes a step (S1) of inducing chemical discharge by opening an external pouch of a used iron phosphate battery in a solution, and a step (S2) of recovering the battery material from the solution after the chemical discharge.

In one specific example of the present invention, prior to the step S1, a step (S0) of charging a used iron phosphate battery is included.

In one specific example of the present invention, in the S0 step, the used iron phosphate battery is charged to an SOC of 50% or more.

In one specific example of the present invention, in the step S1, the chemical discharge supplies the solution into the interior of the used iron phosphate battery to induce a spontaneous reaction between lithium in the negative electrode and the solution.

In one specific example of the present invention, in step S1, the solution causes lithium in the negative electrode of the used iron phosphate battery to move into the solution.

In one specific example of the present invention, in the step S1, the solution contains water or LeS.

In one specific example of the present invention, the LeS comprises water, a solvent that reacts with the negative electrode to release lithium ions into the solution, and an antisolvent that has low solubility in lithium compounds and crystallizes lithium ions in the solution into lithium compounds.

In one specific example of the present invention, the antisolvent includes at least one selected from the group consisting of alcohol (R-OH) series solvents, ketone (R-CO-R') series solvents, ester series (R-COO-R') solvents, carboxylic acid (R-COOH) series solvents, N-Methyl-2-pyrrolidone (NMP), Dimethyl Sulfoxide (DMSO), Ethylene Glycol, Propylene Glycol, Pentane, and Heptane.

In one specific example of the present invention, the alcohol series solvent includes at least one selected from the group consisting of Methanol, Ethanol, 1-Propanol, 2-Propanol (Isopropyl alcohol) (IPA), Sec-Butanol, Iso-Butanol, Tert-Butanol, and Pentanol.

In one specific example of the present invention, the ketone series solvent includes at least one selected from the group consisting of Acetone and Methyl Ethyl Ketone.

In one specific example of the present invention, the ester-based solvent includes at least one selected from the group consisting of Methyl acetate, Ethyl acetate, and Methyl propionate.

In one specific example of the present invention, the volume ratio of water and antisolvent included in the LeS is 9:1 to 1:9.

In one specific example of the present invention, in the step S2, the battery materials are a separator, a negative electrode material, a negative electrode substrate, a positive electrode material, a positive electrode substrate, iron phosphate, and a battery outer shell.

In one specific example of the present invention, after the step S2, a step (S3) of recovering at least one of graphite and lithium is further included.

In one specific example of the present invention, the graphite is recovered by filtering the solution.

In one specific example of the present invention, the lithium is at least one lithium compound including LiOH, LiOH·H ₂ O, LiF, Li ₃ PO ₄ , Li ₂ O, C ₂ H ₅ OLi, LiHCO ₃ or Li ₂ CO ₃ .

In one specific example of the present invention, the lithium is recovered by adding an alcohol-containing solvent to the solution.

According to one aspect of the present invention, the present invention provides a method for disabling an iron phosphate battery material.

In one specific example of the present invention, the method for disabling the iron phosphate battery material includes a step (S1) of inducing chemical discharge by opening an external pouch of a used iron phosphate battery in a solution; and a step (S2) of recovering the battery material from the solution after the chemical discharge.

In one specific example of the present invention, the method for disabling the iron phosphate battery material includes, prior to the step S1, a step (S0) of charging the used iron phosphate battery.

The present invention has the effect of recovering the main materials of used iron phosphate batteries at low cost and high efficiency through a simple process and recycling them as battery raw materials.

In addition, the present invention has the effect of recovering lithium (Li) from a used iron phosphate battery with low energy consumption and in an environmentally friendly manner.

The technical effects of the present invention are not limited to those mentioned above, and other technical effects not mentioned will be clearly understood by those skilled in the art from the description below.

Figure 1 is a process diagram simply illustrating a method for recovering iron phosphate battery material according to one specific example of the present invention.

FIG. 2 is a process schematic diagram simply illustrating a method for recovering iron phosphate battery material from a 1Ah used iron phosphate battery according to one specific example of the present invention.

Figure 3 is a schematic diagram showing a chemical discharge process of an iron phosphate battery material according to one specific example of the present invention.

Figure 4 illustrates the results of XRD analysis of the cathode of a discharged iron phosphate battery according to one specific example of the present invention.

FIG. 5 illustrates the results of XRD analysis of the positive electrode of a used iron phosphate battery in a charged state according to one specific example of the present invention.

Figure 6 illustrates the XRD analysis results of iron phosphate recovered through a method for recovering iron phosphate battery material according to one specific example of the present invention.

Figure 7 illustrates the XRD analysis results of graphite recovered through a method for recovering iron phosphate battery material according to one specific example of the present invention.

FIG. 8 illustrates the results of XRD analysis of lithium powder recovered through a method for recovering iron phosphate battery material according to one specific example of the present invention.

Figure 9 is a process diagram simply illustrating a process for disabling an iron phosphate battery according to one specific example of the present invention.

The specific embodiments provided by the present invention can all be achieved by the following description. It should be understood that the following description describes preferred embodiments of the present invention and is not necessarily limited thereto. Furthermore, like reference numerals designate like elements throughout the specification.

According to one aspect of the present invention, the present invention provides a method for recovering iron phosphate battery materials. Conventional methods for recovering iron phosphate battery materials, such as dry and wet methods, have the disadvantages of using hazardous compounds, which pose environmental problems and require high disposal costs. The present invention provides a method for recovering iron phosphate battery materials, comprising the steps of charging a used iron phosphate battery, inducing chemical discharge, and recovering the battery materials, in order to recover iron phosphate battery materials quickly and efficiently at low cost without using hazardous compounds. Hereinafter, each step of the present invention will be described in detail.

According to one specific example of the present invention, a method for recovering iron phosphate battery material includes a step (S1) of inducing chemical discharge by opening an outer pouch of a used iron phosphate battery in a solution, and a step (S2) of recovering the battery material from the solution after the chemical discharge. The method for recovering iron phosphate battery material may additionally include other steps in addition to the above-described steps S1 and S2. To help understand the method for recovering iron phosphate battery material, FIGS. 1 and 2 provide a process diagram and a process schematic diagram simply illustrating a method for recovering iron phosphate battery material according to one specific example of the present invention.

Step (S0)

According to one specific example of the present invention, a method for recovering iron phosphate battery materials includes, prior to step S1, a step (S0) of charging a spent iron phosphate battery. The step (S0) may be performed in a solution described below, or may be performed in advance outside the solution. At this time, the spent iron phosphate battery may be charged at a charge rate of C-rate 3 or lower. The spent iron phosphate battery may be a lithium secondary battery that uses lithium iron phosphate as a cathode active material and is disposed of due to a decrease in battery capacity. The spent iron phosphate battery may use aluminum foil (Al foil) as a cathode substrate, lithium iron phosphate (LiFePO ₄ ) as a cathode material, copper foil (Cu foil) as an anode substrate, graphite as an anode material, and polypropylene as a separator. The anode of the spent iron phosphate battery charged through the step (S0) may be LiC ₆ . The above step (S0) can move lithium ions existing in the positive electrode to the negative electrode by charging the used iron phosphate battery. Through this, in the step (S1) described below, the thermodynamically unstable charged negative electrode can be reacted with a solution to induce a spontaneous reaction in which lithium ions dissolve in the solution. The above step (S0) can be performed by immersing in a liquid for safety. The liquid is a substance with a high specific heat and no volatility, and may be, but is not limited to, water or oil. The liquid can block oxygen and heat, thereby preventing a fire that may occur during the charging process of the used battery.

According to one specific example of the present invention, the S0 step charges the used iron phosphate battery to a SOC (State Of Charge) of 50% or more. Specifically, the SOC may be 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or an overcharged state.

The above step (S0) can charge the used iron phosphate battery to a SOC (State Of Charge) of 0% or more, but is not limited thereto, and can charge to 0% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, 100% or more, 110% or more, 120% or more, or in an overcharged state. Even when the SOC is in an overcharged state, the used iron phosphate battery can be disabled through opening the pouch in step (S1) described below. In this case, the disablement of the used iron phosphate battery can mean a process of consuming the remaining energy in the battery by removing or weakening the electrical or chemical activity state of the battery for safe disposal or recycling.

Step (S1)

According to one specific example of the present invention, a method for recovering iron phosphate battery materials includes a step (S1) of inducing chemical discharge of a spent iron phosphate battery by opening an outer pouch thereof in a solution. At this time, the spent iron phosphate battery may be a spent iron phosphate battery that has been charged through the above-described step (S0). To facilitate understanding of the chemical discharge process of the spent iron phosphate battery, FIG. 3 provides a schematic diagram illustrating the chemical discharge process of the iron phosphate battery according to one specific example of the present invention. Referring to FIG. 3, the step (S1) may be performed while the spent iron phosphate battery is immersed in the solution. Through the step (S1), the outer pouch of the spent battery may be opened to supply the solution into the interior of the spent battery. The step (S1) may be performed for 1 minute to 168 hours depending on the extent of opening the outer pouch. The spent iron phosphate battery may be disabled through the step (S1). Specifically, step (S1) facilitates the recovery of used iron phosphate battery materials as well as the separation and removal of internal residues by opening the external pouch. Thus, step (S1) enables the safe and effective separation or disposal of internal residues.

According to one specific example of the present invention, in step S1, a solution is supplied into the interior of a spent iron phosphate battery to induce a spontaneous reaction between lithium in the negative electrode and the solution. The lithium in the negative electrode may be lithium (or lithium ion) existing in the negative electrode layered structure or lithium (or lithium ion) forming the negative electrode SEI (Solid Electrolyte Interphase) layer and dendrite. The solution comes into contact with the thermodynamically unstable charged negative electrode inside the spent battery and reacts spontaneously, and lithium is released from the negative electrode, thereby inducing a chemical discharge. Specifically, the solution can cause various physical/chemical reactions, including an exothermic reaction, with the lithium in the negative electrode inside the spent battery, thereby peeling the lithium from the negative electrode substrate (Cu foil).

According to one specific example of the present invention, in step S1, the solution causes lithium within the negative electrode of the spent iron phosphate battery to migrate into the solution. Specifically, the migration may mean that lithium within the negative electrode of the spent iron phosphate battery is extracted into the solution. Through this, lithium within the negative electrode of the spent iron phosphate battery may be dissolved in the solution in the form of lithium ions and exist within the solution in the form of lithium hydroxide, lithium carbonate, or various lithium compounds, or may be precipitated in the form of lithium compounds.

According to one specific example of the present invention, in the step S1, the solution contains water or LeS (Lithium Extraction Solution). Since the water has a high solubility in lithium, high-concentration lithium accumulation is possible during solution recycling or multiple cell processing. However, the high-concentration Li aqueous solution formed by water has a high pH (for example, pH 14 or higher in the case of a 4 M LiOH aqueous solution), which corrodes the metals constituting the iron phosphate battery in a short period of time, thereby lowering the purity of the recovered battery material or requiring an additional process to remove impurities from the recovered battery material. In addition, there is a problem that the amount of lithium loss increases as lithium is inserted into the lattice of the cathode material.

According to one specific embodiment of the present invention, the LeS comprises water, a solvent that reacts with the negative electrode to desorb lithium ions into the solution, and an anti-solvent that has low solubility in lithium compounds and thus crystallizes lithium ions in the solution into lithium compounds. The LeS can lower the concentration of lithium ions in the solution because lithium ions easily precipitate into LeS in the form of LiOH. This can suppress lithium insertion into the lattice of the positive electrode material, thereby increasing the final lithium recovery rate. The LeS reduces -OH ions in the solution as the Li ions precipitate into the form of LiOH, thereby lowering the final pH, thereby suppressing metal corrosion, reducing impurities, and increasing the purity of the overall recovered material. Through this, when LeS is used as a solution, the pH can be maintained at 12.5 or lower even without a separate pH adjuster at each stage. In addition, it can be advantageous for commercialization because it resolves operational difficulties and worker safety issues due to high pH and violent reactions when processing a large number of cells.

According to one specific example of the present invention, the antisolvent may be a solvent of the alcohol (R-OH) series, a solvent of the ketone (R-CO-R') series, a solvent of the ester series (R-COO-R'), a solvent of the carboxylic acid (R-COOH) series, or a solvent such as N-Methyl-2-pyrrolidone (NMP), Dimethyl Sulfoxide (DMSO), Ethylene Glycol, Propylene Glycol, Pentane, and Heptane, either singly or in combination. Specifically, the alcohol series solvent may include Methanol, Ethanol, 1-Propanol, 2-Propanol (Isopropyl alcohol) (IPA), Sec-Butanol, Iso-Butanol, Tert-Butanol, Pentanol, and the like, and the ketone series solvent may include Acetone, Methyl Ethyl Ketone, and the like. As the ester series solvent, methyl acetate, ethyl acetate, methyl propionate, etc. can be used, and as the carboxylic acid series solvent, butyric acid, etc. can be used. The antisolvent is included in LeS and can precipitate lithium as a salt.

According to one specific example of the present invention, the volume ratio of water and antisolvent contained in the LeS is 9:1 to 1:9. By adjusting the volume ratio of water and antisolvent within the above-described range, lithium can be suppressed from being inserted into the lattice of the positive electrode material, and lithium can be precipitated as a salt, thereby increasing the lithium recovery rate. At this time, if the ratio of the antisolvent contained in the LeS is lower than that of water, so that the amount of lithium dissolved and leached in the LeS is low, lithium can be additionally recovered using a method capable of extracting lithium dissolved in a solution, such as LeS evaporation, antisolvent precipitation, and other chemical methods, thereby increasing the total lithium recovery rate.

Step (S2)

According to one specific example of the present invention, a method for recovering iron phosphate battery materials includes a step (S2) of recovering battery materials from a solution after chemical discharge. For safety reasons, step (S2) may be performed within 1 minute to 168 hours after the completion of chemical discharge, but is not limited thereto, and may be performed simultaneously with the start of chemical discharge or during the course of chemical discharge.

According to one specific example of the present invention, the battery materials are a separator, an anode material, an anode substrate, an anode material, an anode substrate, iron phosphate, and a battery outer case. Specifically, the separator may be polypropylene, the anode substrate may be copper foil (Cu foil), and the anode substrate may be aluminum foil (Al foil). In addition, specifically, the battery outer case may be a pouch film of a pouch-type battery, an outer case of a square battery, or a case of a cylindrical battery. At this time, the step (S2) may sequentially recover the separator, the anode substrate, the anode substrate, and iron phosphate. The separator, the anode substrate, the anode substrate, and the iron phosphate may be physically separated and recovered in a solution.

Step (S3)

According to one specific example of the present invention, the method for recovering iron phosphate battery materials further comprises, after step S2, a step (S3) of recovering at least one of graphite and lithium. In this case, step (S3) may be performed simultaneously with step (S2) or before step (S2) to efficiently recover the battery materials. In addition, step (S3) may additionally comprise a step of recovering the positive electrode substrate and positive electrode material from a powder in which graphite, lithium, positive electrode substrate, and positive electrode material are mixed.

According to one specific example of the present invention, the graphite is recovered by filtering the solution. At this time, the graphite may be recovered first, and then the lithium may be recovered. Specifically, the graphite may be recovered by vacuum filtering the solution after step (S2) has been completed. More specifically, the mixed powder containing graphite and lithium recovered from the solution after step (S2) has been redissolved in water, and then the graphite may be recovered through vacuum filtering and water washing.

According to one specific example of the present invention, the lithium (Li) is in the form of one or more lithium compounds including LiOH, LiOH H ₂ O, LiF, Li ₃ PO ₄ , Li ₂ O, C ₂ H ₅ OLi, LiHCO ₃ or Li ₂ CO _3. In order to dry and recover the lithium in the form of Li ₂ CO ₃ , carbon dioxide gas and a carbon dioxide precipitant may be used in the solution. Lithium may be recovered by filtering and separating the Li ₂ CO ₃ precipitated by the carbon dioxide precipitant. CO or CO ₂ may be used as the carbon dioxide gas. As the above carbonate precipitant, one or more carbonate precipitants _selected from the group consisting of sodium carbonate (Na ₂ CO ₃ ), sodium bicarbonate (NaHCO ₃ ), potassium carbonate (K ₂ CO ₃ ), potassium bicarbonate (KHCO ₃ ), calcium carbonate (CaCO ₃ ), magnesium carbonate (MgCO ₃ ), barium carbonate (BaCO 3 ), and dolomite (CaMg(CO ₃ ) ₂ ) can be used. In order to dry and recover the lithium in the form of LiOH, a hydroxide precipitant can be used in the solution. Lithium can be recovered by filtering and separating the LiOH precipitated by the hydroxide precipitant. Ca(OH) ₂ can be used as the above hydroxide precipitant.

According to one specific example of the present invention, the lithium can be recovered by adding an alcohol-containing solvent to the solution. At this time, the solution may be a solution in which graphite has been recovered through reduced pressure filtration after step (S2) is completed. The alcohol-containing solvent may be an insoluble solvent with a solubility in the lithium compound close to or equal to 0.

Specifically, in order to dry and recover the lithium in the form of Li ₂ CO ₃ , isopropyl alcohol (IPA), which has a solubility of 0 in Li ₂ CO ₃ , can be used. At this time, the solution and the alcohol-containing solvent can be mixed in a volume ratio of 1:1 to 1:9. Thereafter, the precipitated Li ₂ CO ₃ can be filtered (e.g., using a Buchner funnel) and dried to recover the lithium in the form of Li ₂ CO ₃ .

In addition, in order to specifically dry and recover the lithium in the form of LiOH, isopropyl alcohol (IPA), which has a solubility of 0 in LiOH, can be used. At this time, the solution and the alcohol-containing solvent can be mixed in a volume ratio of 1:1 to 1:9. Thereafter, the precipitated LiOH slurry can be filtered (e.g., using a Buchner funnel) and dried to recover lithium in the form of LiOH. At this time, in order to prevent CO ₂ and LiOH in the atmosphere from reacting to form Li ₂ CO ₃ , the precipitation, filtering, and separation processes can be performed in an inert gas atmosphere or vacuum. The inert gas can be argon (Ar) or nitrogen (N ₂ ).

A method for recovering iron phosphate battery materials according to one specific embodiment of the present invention consumes minimal energy when recovering lithium. Assuming the conditions in Table 1 below, 1.17 kWh of energy may be consumed per 1 kg of recovered lithium.

division Calculated value Power consumption when charging at 1Ah, 3.65V 3.5Wh Lithium content in a 1 Ah battery 0.49g Number of lithium recovered 0.49g/6.941g·mol ^-1 (lithium molecular weight) = 0.071mol Converted mass of recoverable lithium compound (LiOH·H ₂ O) 0.071 mol x 42 g/mol (LiOH·H ₂ O molecular weight) = 2.98 g Lithium recovery energy consumption 3.5Wh / 2.98g = 1.17kWh/kg

According to one aspect of the present invention, the present invention provides a method for disabling an iron phosphate battery. According to one specific example of the present invention, the method for disabling an iron phosphate battery includes a step (S1) of inducing chemical discharge of a used iron phosphate battery by opening an outer pouch in a solution; and a step (S2) of recovering battery materials from the solution after the chemical discharge. According to one specific example of the present invention, the method for disabling an iron phosphate battery includes a step (S0) of charging the used iron phosphate battery before step S1. Steps (S0) to (S2) of the method for disabling an iron phosphate battery may correspond to steps (S0) to (S2) of the method for recovering iron phosphate battery materials described above.

Below, specific embodiments of the present invention are presented. However, the embodiments described below are intended solely to specifically illustrate or explain the present invention and are not intended to limit the scope of the invention. Furthermore, any details not described herein are technically feasible to those skilled in the art and thus are omitted.

Example

Example 1

LiFePO ₄ as a cathode material, aluminum as a cathode substrate, graphite as a cathode material, copper as a cathode substrate, and LiPF ₆ as an electrolyte. A 1Ah pouch-type spent iron phosphate battery (total weight 25.45 g) using polypropylene as a separator is prepared. Tables 2 and 3 below show the types and contents of materials used in the spent iron phosphate battery and the Li content.

(1) The above used iron phosphate battery is charged to 1C SOC 100% for 1 hour to move lithium to the negative electrode layer structure.

(2) The spent iron phosphate battery charged in LeS is immersed in a mixture of _H2O and Isopropyl Alcohol (IPA) in a volume ratio of 1:3 using a stirrer (Daehan Science Publishing, MSH-20D) at 300 rpm for 30 minutes, and the outer pouch of the spent iron phosphate battery is opened to induce chemical discharge.

(3) After the above chemical discharge is completed, the polypropylene membrane, copper, aluminum, and iron phosphate are recovered from LeS.

(4) The solution that completed step (3) is filtered under reduced pressure to recover a mixed powder of graphite and lithium. After that, lithium is redissolved in 200 ml of water for 24 hours, and graphite is recovered through filtering under reduced pressure and washing with water. The solution from which graphite has been recovered is evaporated and concentrated to about 100 ml, and then the solution and isopropyl alcohol (IPA) are mixed at a volume ratio of 1:4 using a stirrer (Daehan Science Publishing, MSH-20D) at 100 rpm for 3 minutes. After that, the settled lithium precipitate is filtered using a Buchner funnel and dried in the air to recover lithium powder (Li ₂ CO ₃ ).

composition Chemical composition weight(%) Weight (g) Cathode materials and cathode substrates Lithium Iron Phosphate(LiFePO ₄ ), Aluminum(Al) 42.5 10.8 cathode material Graphite(C ₆ ) 18.6 4.7 cathode substrate Copper(Cu) 9.1 2.3 electrolyte Carbonate methyl ethyl (EMC), Ethylene carbonate (EC), Lithium hexafluorophosphate (LiPF ₆ ) 14.0 3.6 membrane Polypropylene 5.1 1.3 External case and charging tab - 10.7 2.7

Li(g) Li(mol) Li (wt%) furtherance 0.5 0.1 1.9

Example 2

The spent iron phosphate battery material was recovered in the same manner as in Example 1, except that the spent iron phosphate battery was charged to 1C SOC 60% for 1 hour to move lithium into the cathode layered structure.

Example 3

The spent iron phosphate battery material was recovered in the same manner as in Example 1, except that the spent iron phosphate battery was charged to 1C SOC 50% for 1 hour to move lithium to the cathode layered structure.

Example 4

The spent iron phosphate battery material was recovered in the same manner as in Example 1, except that the spent iron phosphate battery was immersed in LeS prepared by mixing _H2O and ethanol in a volume ratio of 1:3 using a stirrer at 300 rpm for 30 minutes, and the outer pouch of the spent iron phosphate battery was opened to induce chemical discharge.

Example 5

The spent iron phosphate battery material was recovered in the same manner as in Example 1, except that the spent iron phosphate battery was immersed in LeS prepared by mixing _H2O and methanol in a volume ratio of 1:3 using a stirrer at 300 rpm for 30 minutes, and the outer pouch of the spent iron phosphate battery was opened to induce chemical discharge.

Example 6

The spent iron phosphate battery material was recovered in the same manner as in Example 1, except that the spent iron phosphate battery was immersed in LeS prepared by mixing _H2O and acetone in a volume ratio of 1:3 using a stirrer at 300 rpm for 30 minutes, and the outer pouch of the spent iron phosphate battery was opened to induce chemical discharge.

Example 7

The spent iron phosphate battery material was recovered in the same manner as in Example 1, except that the spent iron phosphate battery was immersed in LeS prepared by mixing _H2O and isopropyl alcohol (IPA) in a 1:1 volume ratio at 300 rpm for 30 minutes using a stirrer, and then the outer pouch of the spent iron phosphate battery was opened to induce chemical discharge.

Example 8

The spent iron phosphate battery material was recovered in the same manner as in Example 1, except that the spent iron phosphate battery was immersed in LeS prepared by mixing _H2O and isopropyl alcohol (IPA) in a volume ratio of 1:9 using a stirrer at 300 rpm for 30 minutes, and the outer pouch of the spent iron phosphate battery was opened to induce chemical discharge.

Example 9

The spent iron phosphate battery material was recovered in the same manner as in Example 1, except that the spent iron phosphate battery was immersed in LeS prepared by mixing _H2O and isopropyl alcohol (IPA) in a volume ratio of 3:1 at 300 rpm for 30 minutes using a stirrer, and then the outer pouch of the spent iron phosphate battery was opened to induce chemical discharge.

Example 10

The spent iron phosphate battery material was recovered in the same manner as in Example 1, except that the spent iron phosphate battery was immersed in LeS prepared by mixing _H2O and isopropyl alcohol (IPA) in a volume ratio of 9:1 at 300 rpm for 30 minutes using a stirrer, and then the outer pouch of the spent iron phosphate battery was opened to induce chemical discharge.

Example 11

The spent iron phosphate battery was immersed in pure water ( _H2O ), the outer pouch of the spent iron phosphate battery was opened to induce chemical discharge, and the spent iron phosphate battery material was recovered in the same manner as in Example 1, except that the lithium re-dissolution process was omitted.

Example 12

The spent iron phosphate battery material was recovered in the same manner as in Example 1, except that the spent iron phosphate battery was immersed in LeS prepared by mixing _H2O and isopropyl alcohol (IPA) in a volume ratio of 5:1 at 300 rpm for 30 minutes using a stirrer, and then the outer pouch of the spent iron phosphate battery was opened to induce chemical discharge.

Example 13

The spent iron phosphate battery material was recovered in the same manner as in Example 1, except that the spent iron phosphate battery was immersed in LeS prepared by mixing _H2O and isopropyl alcohol (IPA) in a volume ratio of 1:5 using a stirrer at 300 rpm for 30 minutes, and the outer pouch of the spent iron phosphate battery was opened to induce chemical discharge.

Example 14

The spent iron phosphate battery material was recovered in the same manner as in Example 1, except that the spent iron phosphate battery was charged to 1C SOC 20% for 1 hour to move lithium into the cathode layered structure.

Example 15

The spent iron phosphate battery material was recovered in the same manner as in Example 1, except that the spent iron phosphate battery was discharged to 1C SOC 0% for 1 hour to move lithium into the positive electrode layer structure.

Example 16

LiFePO ₄ as a cathode material, aluminum as a cathode substrate, graphite as a cathode material, copper as a cathode substrate, and LiPF ₆ as an electrolyte. Prepare a 1Ah pouch-type spent iron phosphate battery (total weight 25.45 g) using polypropylene as a separator.

(1) The above used iron phosphate battery is charged to 1C SOC 120% for 1 hour to move lithium to the negative electrode layer structure.

(2) The spent iron phosphate battery charged in LeS is immersed in a mixture of _H2O and Isopropyl Alcohol (IPA) in a volume ratio of 1:3 using a stirrer (Daehan Science Publishing, MSH-20D) at 300 rpm for 30 minutes, and the outer pouch of the spent iron phosphate battery is opened to induce chemical discharge.

(3) After the above chemical discharge is completed, the polypropylene membrane, copper, aluminum, and iron phosphate are recovered from LeS.

Experimental example

Experimental Example 1 (Analysis of Bipolar Components)

XRD analysis was performed on the positive electrode of the used iron phosphate battery in a discharged state according to Example 1 and the positive electrode of the used iron phosphate battery in a charged state according to Step (1), and the XRD analysis results are shown in FIGS. 4 and 5.

Experimental Example 2 (Analysis of iron phosphate components)

XRD (X-ray Diffraction) analysis was performed on the iron phosphate recovered in Example 1, and the XRD analysis results are shown in Fig. 6. Referring to Fig. 6, it can be confirmed that iron phosphate was recovered from the cathode material.

Experimental Example 3 (Analysis of Graphite Components)

XRD analysis was performed on the graphite recovered in Example 1, and the XRD analysis results are shown in Fig. 7. Referring to Fig. 7, it can be confirmed that the recovered negative electrode material is graphite.

Experimental Example 4 (Li component analysis)

XRD (X-ray Diffraction) analysis was performed on the Li powder recovered in Example 1, and the XRD analysis results are shown in Fig. 8. Referring to Fig. 8, it can be confirmed that it exists in the form of Li ₂ CO ₃ (see “Recovery Li ₂ CO ₃ ” in Fig. 8).

Experimental Example 5 (Analysis of Major Substance Recovery Rate)

The recovery rates for the major substances recovered and separated in Examples 1 to 15 are summarized in Tables 4 to 9 below based on Tables 2 and 3 above. The theoretical recovery amounts in Tables 4 to 9 below are calculated from Table 2 above.

Specifically, Li ₂ Co ₃ is the amount of lithium excluding lithium contained in the positive electrode by SOC state of charge, converted to Li ₂ CO ₃ through ICP analysis. At this time, the total recoverable Li ₂ CO ₃ based on SOC 100% is 2.36 g.

In addition, the "actual recovery amount" in Tables 4 to 9 below is the actual weight measured by drying of each material recovered and separated through Examples 1 to 15. Meanwhile, the recovery rate of Li oxide in Tables 4 to 9 below is calculated based on Li ₂ CO ₃ .

Example 1 Example 2 Example 3 recovered material Theoretical recovery (g) Actual recovery amount (g) Recovery rate (%) Theoretical recovery (g) Actual recovery amount (g) Recovery rate (%) Theoretical recovery (g) Actual recovery amount (g) Recovery rate (%) Li ₂ CO ₃ 2.36 1.51 64.0 1.75 0.95 54.29 1.65 0.64 38.79 black smoke 4.73 4.17 88.16 4.73 4.28 90.49 4.73 4.21 89.01 copper 2.31 2.29 99.13 2.31 2.32 100 2.31 2.40 100 Bipolar material - 10.08 100 - 10.24 100 - 10.23 100

Referring to Table 4 above, it can be confirmed that in Examples 1 to 3, more than 30% of Li ₂ CO ₃ was recovered. Through this, it can be confirmed that when a used iron phosphate battery is charged to 1C SOC 50% or more for 1 hour, lithium moves to the negative electrode layered structure, resulting in a high lithium recovery rate.

Example 4 Example 5 Example 6 recovered material Theoretical recovery (g) Actual recovery amount (g) Recovery rate (%) Actual recovery amount (g) Recovery rate (%) Actual recovery amount (g) Recovery rate (%) Li ₂ CO ₃ 2.36 1.13 47.88 1.01 42.80 1.36 57.63 black smoke 4.73 4.35 91.97 4.24 89.64 4.26 90.06 copper 2.31 2.31 100 2:30 99.57 2.31 100 Bipolar material - 10.01 100 10.10 100 10.15 100

Referring to Table 5 above, it can be confirmed that in Examples 4 to 6, more than 40% of Li ₂ CO ₃ was recovered. Through this, it can be confirmed that when LeS is manufactured by mixing H ₂ O and ethanol, methanol, or acetone in a volume ratio of 1:3, lithium ions are easily precipitated in the form of LiOH in LeS, so the lithium recovery rate is high.

Example 7 Example 8 recovered material Theoretical recovery (g) Actual recovery amount (g) Recovery rate (%) Actual recovery amount (g) Recovery rate (%) Li ₂ CO ₃ 2.36 1.30 55.08 1.57 66.53 black smoke 4.73 4.24 89.64 4.21 89.01 copper 2.31 2.31 100 2.33 100 Bipolar material - 10.13 100 10.08 100

Referring to Table 6 above, it can be confirmed that in Examples 7 and 8, more than 50% of Li ₂ CO ₃ was recovered. Through this, it can be confirmed that when LeS is manufactured by mixing H ₂ O and isopropyl alcohol (IPA) in a volume ratio of 1:1 to 1:9, the amount of lithium ions inserted into the lattice of the cathode material is reduced, so that the lithium recovery rate is high.

Example 9 Example 10 Example 11 recovered material Theoretical recovery (g) Actual recovery amount (g) Recovery rate (%) Actual recovery amount (g) Recovery rate (%) Actual recovery amount (g) Recovery rate (%) Li ₂ CO ₃ 2.36 0.83 35.17 0.03 1.27 1.61 68.22 black smoke 4.73 4.28 90.49 4.17 88.16 4.29 90.70 copper 2.31 2.31 100 2.35 100 2.31 100 Bipolar material - 10.12 100 10.02 100 10.05 100

Referring to Table 7 above, it can be confirmed that in Example 11, more than 60% of Li ₂ CO ₃ was recovered. Through this, it is expected that if lithium is additionally recovered in the same manner as in Example 11 for Examples 9 and 10, in which the ratio of antisolvent in LeS is low and lithium is dissolved in LeS, resulting in a low lithium recovery rate, the lithium recovery rate can be increased.

Example 12 Example 13 recovered material Theoretical recovery (g) Actual recovery amount (g) Recovery rate (%) Actual recovery amount (g) Recovery rate (%) Li ₂ CO ₃ 2.36 0.15 6.36 1.12 47.46 black smoke 4.73 4.25 89.85 4.67 98.73 copper 2.31 2.31 100 2.32 100 Bipolar material - 10.21 100 10.25 100

Referring to Table 8 above, it can be confirmed that Example 13 recovered more than 40% of Li ₂ CO _3. Through this, it can be confirmed that when the ratio of antisolvent in LeS is high, lithium ions are easily precipitated into LeS, resulting in a high lithium recovery rate.

Example 1 Example 14 Example 15 recovered material Theoretical recovery (g) Actual recovery amount (g) Recovery rate (%) Theoretical recovery (g) Actual recovery amount (g) Recovery rate (%) Theoretical recovery (g) Actual recovery amount (g) Recovery rate (%) Li ₂ CO ₃ 2.36 1.51 64.0 1.20 0.41 34.01 - 0.17 100 black smoke 4.73 4.17 88.16 4.73 4.34 91.77 4.73 4.23 89.56 copper 2.31 2.29 99.13 2.31 2.45 100 2.31 2.32 100 Bipolar material - 10.08 100 - 10.27 100 - 10.48 100

Referring to Table 9 above, it can be confirmed that Example 14 recovered more than 30% of Li ₂ CO _3. Through this, it can be confirmed that even if a used iron phosphate battery is charged for 1 hour at 1C SOC 50% or less, lithium moves to the negative electrode layered structure, making lithium recovery possible.

Referring to Table 9 above, it can be confirmed that Li ₂ CO ₃ was recovered in Example 15 as well. Through this, it can be confirmed that even if a used iron phosphate battery is discharged to SOC 0%, it is possible to recover a small amount of lithium contained in the electrolyte.

Experimental Example 6 (Battery Disabling Analysis)

The process for recovering battery materials from the spent iron phosphate battery of Example 16 is illustrated in FIG. 9. Referring to FIG. 9, it can be confirmed that even when the spent iron phosphate battery is overcharged to 120% SOC, battery materials can be reliably recovered and the battery can be disabled. This allows for the safe disposal of spent iron phosphate batteries without the risk of fire or explosion.

All simple modifications or changes of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will be made clear by the appended claims.

Claims (19)

Step (S1) of inducing chemical discharge by opening the external pouch of the used iron phosphate battery in a solution, and A method for recovering iron phosphate battery material, comprising a step (S2) of recovering battery material from a solution after the chemical discharge. In claim 1, Before the above S1 step, A method for recovering iron phosphate battery material, characterized in that it includes a step (S0) of charging a used iron phosphate battery. In claim 2, A method for recovering iron phosphate battery materials, characterized in that, in the above S0 step, the used iron phosphate battery is charged to an SOC of 50% or more. In claim 1, A method for recovering iron phosphate battery materials, characterized in that in the above step S1, the chemical discharge supplies the solution into the interior of the used iron phosphate battery to induce a spontaneous reaction between lithium in the negative electrode and the solution. In claim 1, A method for recovering iron phosphate battery materials, characterized in that in the above step S1, the solution causes lithium in the negative electrode of the used iron phosphate battery to move into the solution. In claim 1, A method for recovering iron phosphate battery material, characterized in that in the above step S1, the solution contains water or LeS. In claim 6, A method for recovering iron phosphate battery material, characterized in that the LeS comprises water, a solvent that reacts with the negative electrode to release lithium ions into a solution, and an antisolvent that has low solubility in lithium compounds and crystallizes lithium ions in the solution into lithium compounds. In claim 7, A method for recovering iron phosphate battery material, characterized in that the antisolvent comprises at least one selected from the group consisting of alcohol (R-OH) series solvents, ketone (R-CO-R') series solvents, ester series (R-COO-R') solvents, carboxylic acid (R-COOH) series solvents, N-Methyl-2-pyrrolidone (NMP), Dimethyl Sulfoxide (DMSO), Ethylene Glycol, Propylene Glycol, Pentane, and Heptane. In claim 8, A method for recovering iron phosphate battery material, characterized in that the alcohol series solvent includes at least one selected from the group consisting of Methanol, Ethanol, 1-Propanol, 2-Propanol (Isopropyl alcohol) (IPA), Sec-Butanol, Iso-Butanol, Tert-Butanol, and Pentanol. In claim 8, A method for recovering iron phosphate battery material, characterized in that the above ketone series solvent comprises at least one selected from the group consisting of acetone and methyl ethyl ketone. In claim 8, A method for recovering iron phosphate battery material, characterized in that the above ester series solvent comprises at least one selected from the group consisting of methyl acetate, ethyl acetate, and methyl propionate. In claim 7, A method for recovering iron phosphate battery material, characterized in that the volume ratio of water and antisolvent included in the above LeS is 9:1 to 1:9. In claim 1, A method for recovering iron phosphate battery materials, characterized in that in the above step S2, the battery materials are a separator, a cathode material, a cathode substrate, a cathode material, a cathode substrate, iron phosphate, and a battery outer material. In claim 1, A method for recovering iron phosphate battery material, characterized in that it further comprises a step (S3) of recovering at least one of graphite and lithium after the above step S2. In claim 14, A method for recovering iron phosphate battery material, characterized in that the graphite is recovered by filtering the solution. In claim 14, A method for recovering an iron phosphate battery material, characterized in that the lithium is in the form of one or more lithium compounds including LiOH, LiOH·H ₂ O, LiF, Li ₃ PO ₄ , Li ₂ O, C ₂ H ₅ OLi, LiHCO ₃ or Li ₂ CO ₃ . In claim 14, A method for recovering a battery material, characterized in that the lithium is recovered by adding an alcohol-containing solvent to the solution. Step (S1) of inducing chemical discharge of a used iron phosphate battery by opening the outer pouch in a solution; and A method for disabling an iron phosphate battery, comprising a step (S2) of recovering battery material from a solution after the chemical discharge. In claim 18, Before the above S1 step, A method for disabling an iron phosphate battery, characterized in that it comprises a step (S0) of charging a used iron phosphate battery.