Method for recovering lithium precursor

Abstract

In the method for recovering a lithium precursor, electrode powder and carbon dioxide are added to a solvent so as to form an electrode powder solution. An oxidizing agent is added in portions to the electrode powder solution so as to generate a lithium precursor solution. The oxidation-reduction-potential (ORP) change rate of the lithium precursor solution, calculated by equation 1, is 80% or more. According to the method for recovering a lithium precursor, of the present disclosure, a lithium recovery rate can be improved.

Description

Lithium precursor recovery method

[0001] The present disclosure relates to a method for recovering a lithium precursor. More specifically, it relates to a method for recovering a lithium precursor from a lithium secondary battery.

[0002]

[0003] Rechargeable batteries are batteries capable of repeated charging and discharging, and with the advancement of the information and communication and display industries, they are widely applied as power sources for portable electronic communication devices such as camcorders, mobile phones, and laptop PCs. Furthermore, recently, battery modules or battery packs containing rechargeable batteries are being developed and applied as power sources for eco-friendly vehicles.

[0004] For example, a secondary battery may include an electrode assembly comprising a positive electrode, a negative electrode, and a separator, and an electrolyte impregnating the electrode assembly. The secondary battery may further include an outer casing that accommodates the electrode assembly and the electrolyte. Depending on the shape of the outer casing, the secondary battery may be classified as a coin-type, prismatic, cylindrical, or pouch-type secondary battery.

[0005] Secondary batteries include, for example, lead-acid batteries, nickel-cadmium batteries (NiCd), nickel-metal hydride batteries (Ni-MH), lithium secondary batteries, etc. The lithium secondary batteries include lithium-ion batteries (Li-ion), lithium polymer batteries (Li-Po), lithium iron phosphate batteries (LiFePO4), lithium sulfur batteries (Li-S), etc.

[0006] With the increasing demand for secondary batteries, research on recycling methods is on the rise due to environmental protection issues and the cost of metal materials. For example, secondary batteries can be crushed to form electrode powder, and the metal can be recovered by oxidizing the electrode powder. However, this recovery process requires numerous steps, and costs associated with waste generation may increase. Therefore, there is a need for methods to efficiently recycle secondary batteries.

[0007]

[0008] One objective of the present disclosure is to provide a method for recovering a lithium precursor with high efficiency.

[0009]

[0010] In a method for recovering a lithium precursor according to exemplary embodiments, electrode powder and carbon dioxide are introduced into a solvent to form an electrode powder solution. An oxidizing agent is introduced in portions into the electrode powder solution to produce a lithium precursor solution.

[0011] The change rate of the Oxidation-Reduction Potential (ORP) of the lithium precursor solution calculated by the following Equation 1 may be 80% or more.

[0012] [Equation 1]

[0013] ORP Change Rate (%) =

[0014] In the above Equation 1, O i represents the initial ORP value measured 30 minutes after the start of the addition of the oxidizing agent to the electrode powder solution, and O f represents the late ORP value measured at a time when 120 minutes have elapsed from the time the oxidizing agent was introduced into the electrode powder solution, and O i and O f It can be based on a value converted based on the standard hydrogen electrode (SHE).

[0015] According to exemplary embodiments, the ORP change rate of the lithium precursor solution may be 90% or more.

[0016] According to exemplary embodiments, the ORP value of the lithium precursor solution produced in the step of producing the lithium precursor solution can be maintained at 200 mV or higher.

[0017] In some embodiments, the ORP value of the lithium precursor solution may be maintained at 200 mV to 1,770 mV.

[0018] According to exemplary embodiments, the electrode powder may contain iron.

[0019] According to exemplary embodiments, the oxidizing agent can be divided and added six or more times.

[0020] In some embodiments, the molar ratio of the oxidizing agent to the iron contained in the electrode powder may be 0.4 to 1.0.

[0021] In some embodiments, the time interval between the divided inputs may be 30 minutes or less.

[0022] According to exemplary embodiments, the molar ratio of the oxidizing agent to the iron contained in the electrode powder is 1.0 to 1.5, and the oxidizing agent can be added in 2 to 5 divided doses.

[0023] In some embodiments, the time interval between the divided inputs may be 1 hour or less.

[0024] According to exemplary embodiments, the oxidizing agent may be divided and introduced at a rate of 0.001 mol / min to 0.02 mol / min based on the molar amount of iron contained in the electrode powder.

[0025] According to exemplary embodiments, the electrode powder contains lithium, and the carbon dioxide may be introduced at a rate of 0.5 L / min to 4.5 L / min per 1 g of lithium contained in the electrode powder.

[0026] According to exemplary embodiments, the solvent may include an aqueous solvent from which strong acids are excluded.

[0027] According to exemplary embodiments, a solid containing iron may be produced in the step of producing the lithium precursor solution.

[0028] In some embodiments, the step of separating the solid containing iron from the liquid may be further included.

[0029] According to exemplary embodiments, the step of heat-treating the lithium precursor solution may be further included.

[0030] According to exemplary embodiments, the oxidizing agent may include one or more of hydrogen peroxide, ozone water, perbromic acid, perchloric acid, and periodic acid.

[0031]

[0032] According to the lithium precursor recovery method of the present disclosure, an oxidizing agent can be introduced in divided portions. Accordingly, the lithium recovery rate can be improved while efficiently controlling the amount of oxidizing agent introduced.

[0033] According to exemplary embodiments, the Oxidation-Reduction Potential (ORP) of the resulting lithium precursor solution can be maintained above a certain level. Accordingly, the lithium precursor generation reaction can be carried out efficiently, thereby improving the lithium recovery rate.

[0034]

[0035] FIG. 1 is a schematic flowchart illustrating a method for recovering a lithium precursor according to exemplary embodiments.

[0036]

[0037] According to the lithium precursor recovery method according to the embodiments of the present disclosure, electrode powder can be prepared from a lithium iron phosphate battery. An electrode powder solution can be formed by introducing the electrode powder and carbon dioxide into a solvent, and a lithium precursor solution can be produced by adding an oxidizing agent in portions to the electrode powder solution. A lithium precursor can be recovered through the lithium precursor solution.

[0038] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings. However, this is merely illustrative and the present disclosure is not limited to the specific embodiments described illustratively.

[0039] As used in this specification, the term "precursor" is used to collectively refer to a compound containing a specific metal to provide the specific metal included in the electrode active material. For example, a lithium precursor is a compound containing lithium, and may include lithium hydroxide (LiOH), lithium carbonate (Li2CO3), lithium fluoride (LiF), etc.

[0040] As used in this specification, the term "electrode powder" is used to comprehensively refer to a material in powder form generated from a battery. For example, the electrode powder may include a positive electrode active material, a conductive material, a binder, etc., generated by grinding a lithium secondary battery (e.g., a lithium nickel-manganese-cobalt battery, a lithium nickel-cobalt-manganese-aluminum battery, a lithium iron phosphate battery, etc.).

[0041] The term "divided input" as used in this specification may indicate that an input substance is divided and injected over a period of time. For example, it may indicate that an input substance is divided and injected over a period of time of 1 minute or more, 5 minutes or more, or 10 minutes or more. For example, cases in which an input substance is injected intermittently at time intervals of 10 minutes or more, and cases in which an input substance is injected continuously for a period of 10 minutes or more, may all be included in the divided input.

[0042] FIG. 1 is a schematic flowchart illustrating a method for recovering a lithium precursor according to exemplary embodiments.

[0043] Referring to FIG. 1, electrode powder can be prepared (e.g., process S10).

[0044] For example, electrode powder can be prepared from a lithium secondary battery. The lithium secondary battery may include a nickel-based lithium secondary battery containing nickel, cobalt, and manganese, and / or an iron phosphate-based lithium secondary battery containing iron and phosphorus, etc.

[0045] The above lithium secondary battery may include an electrode assembly comprising a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. The positive electrode and the negative electrode may each include a positive active material layer and a negative active material layer coated on a positive current collector and a negative current collector, respectively.

[0046] The above cathode includes a cathode current collector (e.g., copper (Cu)) and a cathode active material layer, and the cathode active material layer may include a cathode active material, a conductive material, and a binder together.

[0047] For example, the above-mentioned negative electrode active material capable of absorbing and extracting lithium ions may be used without special limitation if it is known in the art. For example, the above-mentioned negative electrode active material may include carbon-based materials such as crystalline carbon, amorphous carbon, carbon composites, carbon fibers; lithium alloys; silicon (Si)-based compounds or tin, etc.

[0048] The conductive material may include, for example, carbon-based materials such as graphite, carbon black, graphene, carbon nanotubes, etc. The binder may include, for example, resin materials such as vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidenefluoride (PVDF), polyacrylonitrile, and polymethylmethacrylate.

[0049] The above-mentioned anode comprises an anode current collector (e.g., aluminum (Al)) and an anode active material layer, and the anode active material layer may include the anode active material together with the aforementioned conductive material and binder.

[0050] The above-mentioned anode may be obtained from spent lithium secondary batteries. For example, the above-mentioned anode may include a used spent lithium secondary battery anode, an anode that was damaged or defective during the manufacturing process, etc.

[0051] In some embodiments, the anode may be obtained from a spent lithium iron phosphate battery.

[0052] According to exemplary embodiments, the anode can be crushed to recover electrode powder containing an anode active material.

[0053] In some embodiments, the electrode powder may include black powder obtained by physically crushing spent lithium iron phosphate batteries. When introduced into a solvent in the form of black powder, a reaction with carbon dioxide and an oxidizing agent may be promoted.

[0054] The above positive active material may include metals such as lithium, nickel, cobalt, manganese, and iron, for example. The above positive active material may include non-metals such as phosphoric acid, for example.

[0055] According to exemplary embodiments, the positive electrode active material may include lithium. For example, the positive electrode active material may include lithium and nickel. For example, the positive electrode active material may include lithium and iron.

[0056] In some embodiments, the positive electrode active material may comprise a lithium iron phosphate (LiFePO4, LFP)-based lithium oxide comprising lithium, iron, and phosphoric acid. For example, the positive electrode active material may comprise lithium iron phosphate (LiFePO4).

[0057] In some embodiments, the electrode powder containing the positive active material may be heat-treated. The heat treatment may be performed before being introduced into the solvent described below. For example, the heat treatment may be performed at 100°C to 900°C, or at 350°C to 800°C.

[0058] Impurities such as conductive materials and binders can be removed or reduced by the above heat treatment. Accordingly, a lithium precursor can be recovered from electrode powder containing a high-purity positive electrode active material.

[0059] According to exemplary embodiments, electrode powder and carbon dioxide can be introduced into a solvent (e.g., process S21).

[0060] For example, an electrode powder solution can be formed by introducing electrode powder and carbon dioxide into a solvent.

[0061] The above solvent may include an aqueous solvent. For example, the above aqueous solvent may include water; water-soluble organic solvents such as ethanol, acetone, etc.

[0062] According to exemplary embodiments, the solvent may include an aqueous solvent from which strong acids are excluded.

[0063] For example, strong acids may include sulfuric acid, hydrochloric acid, nitric acid, etc. As strong acids are excluded, byproducts such as sodium sulfate (Na2SO4) resulting from the reaction between the cathode active material and strong acids may not be generated. Therefore, since additional processes for byproduct removal are not required, lithium precursors can be recovered efficiently and in an environmentally friendly manner.

[0064] According to exemplary embodiments, the content of the solvent may be 50 to 500 parts by weight, 60 to 350 parts by weight, or 70 to 200 parts by weight relative to 10 parts by weight of the electrode powder. Within the above content range, the electrode powder, oxidizing agent, and / or carbon dioxide are efficiently dissolved, and the reaction can be promoted.

[0065] Carbon dioxide can produce a lithium precursor solution containing a lithium salt together with the above-mentioned oxidizing agent.

[0066] For example, carbon dioxide can react with the electrode powder and the oxidizing agent to produce a lithium salt. For example, the lithium salt can be efficiently produced by controlling the input rate of carbon dioxide based on the weight or moles of lithium contained in the electrode powder.

[0067] According to exemplary embodiments, the rate of carbon dioxide input per 1 g of lithium contained in the electrode powder may be 0.5 L / min or more. In some embodiments, the rate of carbon dioxide input may be 0.7 L / min or more, 0.9 L / min or more, 1.0 L / min or more, or 1.2 L / min or more.

[0068] According to exemplary embodiments, the rate of carbon dioxide input per 1 g of lithium contained in the electrode powder may be 4.5 L / min or less. In some embodiments, the rate of carbon dioxide input may be 4.3 L / min or less, 4.2 L / min or less, 4.0 L / min or less, 3.8 L / min or less, or 3.5 L / min or less.

[0069] For example, the rate of carbon dioxide input per 1g of lithium contained in the electrode powder may be 0.5 L / min to 4.5 L / min, 0.7 L / min to 4.3 L / min, 0.9 L / min to 4.2 L / min, 1.0 L / min to 4.0 L / min, or 1.2 L / min to 3.5 L / min.

[0070] In some embodiments, the rate of carbon dioxide input per 0.9g of lithium contained in the electrode powder may be 1 L / min to 4 L / min, 1.1 L / min to 3.8 L / min, or 1.2 L / min to 3.5 L / min.

[0071] Carbon dioxide introduced within the above numerical range can improve reaction efficiency in conjunction with the divided introduction of the oxidizing agent described below.

[0072] According to exemplary embodiments, an oxidizing agent can be divided and added to the electrode powder solution (e.g., process S22).

[0073] The above oxidizing agent can oxidize the positive active material contained in the electrode powder together with the above carbon dioxide to convert it into a lithium salt form, thereby producing a lithium precursor solution containing a lithium salt.

[0074] The efficiency of lithium salt production can be improved by the divided input of the above-mentioned oxidizing agent. For example, if the above-mentioned oxidizing agent is not divided, it may be difficult to maintain an oxidation atmosphere, and consequently, the efficiency of the lithium salt production reaction may decrease. In addition, the generation of byproducts caused by impurities in the electrode powder and the oxidizing agent and / or carbon dioxide may increase.

[0075] The above oxidizing agent can be divided and added based on the stoichiometric equivalent amount as the total amount. For example, if the stoichiometric equivalent amount of the above oxidizing agent is 1 mole, it can be divided and added twice in 0.5 mole portions.

[0076] According to exemplary embodiments, the oxidizing agent may include a peroxide. For example, the oxidizing agent may include hydrogen peroxide (H2O2), ozone water, perbromic acid, perchloric acid, periodic acid, sodium peroxide, sodium persulfate, ammonium persulfate, etc.

[0077] According to exemplary embodiments, the oxidizing agent may include one or more of hydrogen peroxide, ozone water, perbromic acid, perchloric acid, and periodic acid.

[0078] In some embodiments, the oxidizing agent may include hydrogen peroxide (H2O2). When hydrogen peroxide is used, the generation of impurities can be suppressed, thereby improving the efficiency of lithium precursor recovery. In addition, even if byproducts are generated, water (H2O) is produced, so the lithium precursor can be recovered in an environmentally friendly manner.

[0079] In some embodiments, the change rate of the Oxidation-Reduction Potential (ORP) of the lithium precursor solution calculated by the following Formula 1 may be 80% or more.

[0080] [Equation 1]

[0081] ORP Change Rate (%) =

[0082] In Equation 1, O i represents the initial ORP value measured 30 minutes after the start of the addition of the oxidizing agent to the electrode powder solution, and O f represents the late ORP value measured at a time when 120 minutes have elapsed from the time the oxidizing agent was introduced into the electrode powder solution, and O i and O f It is based on a value converted based on the standard hydrogen electrode (SHE).

[0083] The ORP meter may be equipped with, for example, an Ag / AgCl reference electrode.

[0084] O i and O f The value can be converted into a standard hydrogen electrode (SHE) reference value by applying a potential correction value to the value measured by the ORP meter.

[0085] O i and O f It can be measured at room temperature. As a non-limiting example, Oi and Of can be measured under an alkali metal chloride electrolyte solution.

[0086] For example, it can be measured using an ORP meter equipped with an Ag / AgCl reference electrode containing a 3M KCl solution as an internal electrolyte, and the measured value can be converted and displayed based on a standard hydrogen electrode (SHE).

[0087] For example, if the internal electrolyte of the Ag / AgCl electrode is 3M KCl, the converted potential based on the standard hydrogen electrode (SHE) at 25 ℃ may be approximately +0.210 V.

[0088] The above ORP value can be measured using an ORP measuring device. The above ORP can be measured using an ORP measuring device known in the art. For example, the above ORP value can be measured using an ORP measuring device (Mettler Toledo) with an Ag / AgCl electrode or a Standard Hydrogen Electrode (SHE) as the reference electrode. For example, the probe of the above ORP measuring device can be introduced into the slurry to measure the ORP value while the lithium precursor solution is being formed. For example, if an Ag / AgCl electrode is used as the reference electrode, the value can be converted to the SHE reference ORP value through a program.

[0089] The above initial 30 minutes may represent 30 minutes from the time the oxidizing agent is first introduced.

[0090] For example, the ORP value measured at the time when the initial 30 minutes have elapsed from the time the oxidizing agent was first added to the solvent can be used as a basis.

[0091] According to exemplary embodiments, the ORP change rate of the lithium precursor solution may be 90% or more, 90.2% or more, 90.4% or more, 90.5% or more, 90.6% or more, 90.7% or more, 90.8% or more, 90.9% or more, or 91% or more.

[0092] According to exemplary embodiments, the ORP change rate of the lithium precursor solution may be 200% or less, 180% or less, 170% or less, 160% or less, 150% or less, 135% or less, or 120% or less.

[0093] For example, the ORP change rate of the lithium precursor solution may be 90% to 200%, 90.2% to 180%, 90.4% to 160%, 90.5% to 150%, 90.8% to 135%, or 91% to 120%.

[0094] As it is maintained within the above range, an oxidizing atmosphere can be maintained, and accordingly, the production rate of lithium precursors can be increased, thereby improving the lithium precursor recovery efficiency.

[0095] For example, if the ORP change rate of the lithium precursor solution is below the above range, the reaction rate of the oxidation reaction may decrease, and consequently, the lithium recovery rate may decrease. For example, if the ORP change rate of the lithium precursor solution exceeds the above range, side reactions other than the oxidation reaction by the oxidizing agent may occur, and consequently, the purity and recovery rate may decrease.

[0096] According to exemplary embodiments, the ORP value of the lithium precursor solution can be maintained at 200 mV or higher.

[0097] In some embodiments, the ORP value of the lithium precursor solution may be maintained at 200 mV or higher, 201 mV or higher, 203 mV or higher, 204 mV or higher, or 205 mV or higher.

[0098] In some embodiments, the ORP value of the lithium precursor solution may be maintained at 1,770 mV or less, 1,650 mV or less, 1,500 mV or less, 1,350 mV or less, 1,200 mV or less, or 1,000 mV or less.

[0099] For example, the ORP value of the lithium precursor solution may be 200 mV to 1,770 mV, 201 mV to 1,650 mV, 203 mV to 1,500 mV, 204 mV to 1,350 mV, 204 mV to 1,200 mV, or 205 mV to 1,000 mV.

[0100] The recovery efficiency of the lithium precursor can be improved within the above range. For example, if the ORP value is below the above range, the generation of byproducts is not suppressed, so the amount of lithium salt produced may decrease, and accordingly, the recovery rate of the lithium precursor may decrease.

[0101] According to exemplary embodiments, the divided injection of the oxidizing agent may be injected together with or after carbon dioxide to control the Oxidation-Reduction Potential (ORP) value. Accordingly, control of the ORP value may be possible through the divided injection of the oxidizing agent.

[0102] The total amount of oxidizing agent to be added can be adjusted by considering the numerical value of the ORP of the lithium precursor solution, the time interval between divided additions, the number of divided additions, etc.

[0103] According to exemplary embodiments, the electrode powder contains iron, and the ratio of the total moles of the oxidizing agent added to the total moles of iron contained in the electrode powder may be 0.4 to 2.0.

[0104] Lithium salts can be produced by an oxidation reaction within the above range.

[0105] The total content of the oxidizing agent introduced can be controlled according to the number of divided introductions of the oxidizing agent. The content of the oxidizing agent introduced in the divided introductions can be controlled based on the total number of moles of iron contained in the electrode powder.

[0106] For example, if the number of divided inputs of the oxidizing agent is relatively increased, the content of the oxidizing agent being input can be reduced, and accordingly, the consumption of the reactant can be reduced, thereby improving process efficiency.

[0107] For example, if the number of divided inputs of the oxidizing agent is relatively reduced, the content of the oxidizing agent being input may increase, but the variation due to divided inputs is reduced, so the purity of the resulting lithium salt can be maintained above a certain level.

[0108] For example, the reaction time from the time the oxidizing agent is first added may be 2 hours.

[0109] The time interval of the divided injection can be adjusted according to the number of divided injections of the above-mentioned oxidizing agent.

[0110] For example, if the number of divided injections of the oxidizing agent increases relatively, the time interval between divided injections can be reduced. For example, if the number of divided injections of the oxidizing agent decreases relatively, the time interval between divided injections can be increased.

[0111] According to exemplary embodiments, the number of divided injections of the oxidizing agent may be 6 or more (hereinafter abbreviated as "first divided injection"). In some embodiments, the first divided injection of the oxidizing agent may be 6 to 15 times, 6 to 14 times, 6 to 13 times, or 6 to 12 times.

[0112] In some embodiments, within the first number of divided inputs, the ratio of the total moles of the oxidizing agent to the total moles of iron contained in the electrode powder may be 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.71 or more, 0.71 to 1.75, 0.72 to 1.5, 0.73 to 1.4, 0.74 to 1.35, 0.75 to 1.3, or 0.75 or more and less than 1.3.

[0113] Within the above range, a high lithium precursor recovery rate can be achieved from a relatively small amount of oxidant.

[0114] In some embodiments, within the first number of divided inputs, the time interval between divided inputs may be 30 minutes or less, 5 minutes to 30 minutes, 6 minutes to 28 minutes, 7 minutes to 27 minutes, 8 minutes to 26 minutes, or 10 minutes to 25 minutes.

[0115] The oxidation atmosphere can be maintained through the above time interval, and accordingly, the generation efficiency of the lithium precursor solution can be improved.

[0116] According to exemplary embodiments, the number of times the oxidizing agent is divided and added may be 2 to 5 times, 2 to 4 times, or 3 to 4 times (hereinafter referred to as "second divided addition time").

[0117] In some embodiments, within the second divided input number, the ratio of the total moles of the oxidizing agent to the total moles of iron contained in the electrode powder may be 1.20 or more, 1.22 or more, 1.23 to 2.0, 1.24 to 1.95, 1.25 to 1.9, 1.25 to 1.85, or less than 1.25 to 1.8.

[0118] Within the above range, it is possible to maintain an oxidation atmosphere even with a small number of divided inputs. Additionally, as the number of inputs decreases, the deviation decreases, allowing for the realization of a lithium recovery rate above a certain level.

[0119] In some embodiments, within the second number of divided inputs, the time interval between divided inputs may be 1 hour or less, 30 minutes to 1 hour or less, 31 minutes to 55 minutes, 32 minutes to 53 minutes, 33 minutes to 52 minutes, 34 minutes to 51 minutes, or 35 minutes to 50 minutes.

[0120] The oxidation atmosphere can be maintained through the above time interval, and accordingly, the generation efficiency of the lithium precursor solution can be improved.

[0121] According to exemplary embodiments, the amount of oxidizing agent added in each of the divided additions may be the same.

[0122] For example, if the equivalent amount of the oxidizing agent is 1.25 relative to the iron contained in the electrode powder, the oxidizing agent may be added in eight divided doses of approximately 0.16 equivalents each.

[0123] As the amount of oxidizing agent added is maintained at a constant level, the reaction rate and reaction time of the lithium salt can be maintained at a constant level, and accordingly, repeatability can be achieved.

[0124] The above oxidizing agent may also be injected in divided portions at an injection rate within a predetermined range over a certain period of time.

[0125] According to exemplary embodiments, the oxidizing agent may be divided and introduced at a rate of 0.001 mol / min or more based on the molar amount of iron contained in the electrode powder. In some embodiments, the oxidizing agent may be divided and introduced at a rate of 0.002 mol / min or more, 0.004 mol / min or more, 0.005 mol / min to 0.02 mol / min, 0.006 mol / min to 0.018 mol / min, 0.007 mol / min to 0.016 mol / min, or 0.0075 mol / min to 0.015 mol / min based on the molar amount of iron contained in the electrode powder.

[0126] Oxidizers divided and injected at the above range of speeds can further reduce the change in the ORP value.

[0127] The order of the step of adding the oxidizing agent in divided portions may not be limited. For example, the addition of the oxidizing agent in divided portions may be performed together with the addition of the electrode powder and carbon dioxide. Alternatively, the addition of the oxidizing agent in divided portions may be performed after the addition of the electrode powder and carbon dioxide.

[0128] According to exemplary embodiments, the reaction of the electrode powder, carbon dioxide, and the oxidizing agent may proceed according to the following reaction scheme 1.

[0129] [Reaction Equation 1]

[0130] 2LiFePO4(s) + H2O2(aq) + 2CO2(aq) → 2LiHCO3(aq) + 2FePO4(s)

[0131] According to exemplary embodiments, the reaction of the electrode powder, carbon dioxide, and the oxidizing agent may proceed according to the following reaction scheme 1-1 and / or reaction scheme 1-2.

[0132] [Reaction Equation 1-1]

[0133] LiFePO4(s) + 0.5H2O2(aq) → FePO4(s) + LiOH (aq)

[0134] [Reaction Equation 1-2]

[0135] LiOH(aq) + CO2(aq) → LiHCO3(aq)

[0136] According to the above reaction, the lithium precursor solution may contain lithium hydroxide or lithium carbonate.

[0137] According to exemplary embodiments, a lithium precursor can be recovered from the lithium precursor solution (e.g., process S30).

[0138] According to exemplary embodiments, a solid containing iron can be produced by the reaction of the electrode powder, the oxidizing agent, and the carbon dioxide. For example, a solid containing iron can be produced according to the reaction scheme 1-1 described above.

[0139] According to exemplary embodiments, the step of separating the solid containing iron from the liquid may be further included.

[0140] The step of separating the solid containing the iron from the solid can be performed before recovering the lithium precursor. For example, the lithium precursor can be recovered after the solid is recovered through solid-liquid separation.

[0141] In some embodiments, the iron-containing solid may comprise iron phosphate (FePO4). The iron phosphate may be recycled by solid-liquid separation from the preliminary lithium precursor solution. For example, the separated iron phosphate may be recycled into a lithium iron phosphate battery.

[0142] According to exemplary embodiments, the lithium precursor solution may comprise a lithium salt containing carbonate ions. The carbonate ions are carbonate ions (CO3 2- ), bicarbonate ion (HCO3 - It may contain one or more of ions derived from carbonic acid (H2CO3). Lithium salts containing carbonate ions can be easily recovered by heating the lithium precursor solution.

[0143] According to exemplary embodiments, the lithium precursor can be recovered by heat-treating the lithium precursor solution.

[0144] The above heat treatment can be performed within a temperature range in which the solvent can be evaporated. For example, the heat treatment can be performed at 60°C to 150°C, and depending on the heat treatment, a lithium salt solid containing carbonate ions can be obtained. A lithium precursor can be obtained within the above temperature range without damage to the crystal structure.

[0145] For example, the lithium salt containing the carbonate ion may include lithium bicarbonate (LiHCO3), and the lithium bicarbonate may be converted into lithium carbonate (Li2CO3) by heat treatment. Accordingly, a lithium precursor can be recovered in the form of lithium carbonate.

[0146] According to exemplary embodiments, the content of lithium in the total content of lithium, iron, and phosphorus contained in the lithium precursor solution may be 70 wt% or more, 75 wt% or more, or 80 wt% or more. The upper limit of the content of lithium in the total content of lithium, iron, and phosphorus contained in the lithium precursor solution is not limited, but may be, for example, 99 wt% or less, 97 wt% or less, 96 wt% or less, or 95 wt% or less. As lithium is optionally leached, a lithium precursor solution containing lithium within the above content range may be formed.

[0147] According to exemplary embodiments, the leaching rate of lithium can be calculated from the lithium content contained in the lithium precursor solution according to the following Equation 2.

[0148] [Equation 2]

[0149] Leaching rate (%) = (Weight of element contained in the lithium precursor solution after time / Weight of element contained in the electrode powder) * 100

[0150] According to exemplary embodiments, the leaching rate of lithium may be 85% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 92.5% or more, or 93% or more. The upper limit of the leaching rate of lithium is not limited, but may be, for example, 99.9% or less, 99.5% or less, or 99% or less.

[0151] According to exemplary embodiments, the lithium recovery rate can be calculated from the lithium content contained in the lithium precursor solution according to the following Equation 3.

[0152] [Equation 3]

[0153] Lithium recovery rate (%) = (Weight of lithium contained in the recovered lithium precursor / Weight of lithium contained in the electrode powder) X 100

[0154] According to exemplary embodiments, the recovery rate of lithium may be 70% or more, 72% or more, 75% or more, 78% or more, 80% or more, 82% or more, 84% or more, 84.5% or more, or 85% or more. The upper limit of the lithium recovery rate is not limited, but may be, for example, 99.9% or less, 99.5% or less, or 99% or less.

[0155] High-purity lithium precursors can be obtained with leaching rates and / or recovery rates within the above range.

[0156]

[0157] The embodiments of the present disclosure described above include the following aspects and can be implemented through at least one of the following aspects.

[0158] A method for recovering a lithium precursor according to the first aspect of the present disclosure comprises the steps of: introducing electrode powder and carbon dioxide into a solvent to form an electrode powder solution; and introducing an oxidizing agent in portions into the electrode powder solution to produce a lithium precursor solution.

[0159] The change rate of the Oxidation-Reduction Potential (ORP) of the lithium precursor solution calculated by the following Equation 1 may be 80% or more.

[0160] [Equation 1]

[0161] ORP Change Rate (%) =

[0162] In the above Equation 1, O i represents the initial ORP value measured 30 minutes after the start of the addition of the oxidizing agent to the electrode powder solution, and O frepresents the late ORP value measured at a time when 120 minutes have elapsed from the time the oxidizing agent was introduced into the electrode powder solution, and O i and O f It can be based on a value converted based on the standard hydrogen electrode (SHE).

[0163] In the first aspect above, according to the second aspect, the ORP change rate of the lithium precursor solution may be 90% or more.

[0164] According to the first aspect or the second aspect, and the third aspect, in the step of producing the lithium precursor solution, the ORP value of the lithium precursor solution can be maintained at 200 mV or higher.

[0165] In the third aspect above, according to the fourth aspect, the ORP value of the lithium precursor solution can be maintained at 200 mV to 1,770 mV.

[0166] In any one of the first to fourth aspects above, according to the fifth aspect, the electrode powder may include iron.

[0167] In the above fifth aspect, according to the sixth aspect, the oxidizing agent can be divided and injected six or more times.

[0168] In the sixth aspect above, according to the seventh aspect, the molar ratio of the oxidizing agent to the iron contained in the electrode powder may be 0.4 to 1.0.

[0169] In the above-mentioned sixth aspect, according to the eighth aspect, the time interval between the split inputs may be 30 minutes or less.

[0170] In the fifth aspect above, according to the ninth aspect, the molar ratio of the oxidizing agent to the iron contained in the electrode powder is 1.0 to 1.5, and the oxidizing agent can be divided and added 2 to 5 times.

[0171] In the ninth aspect above, according to the tenth aspect, the time interval between the split inputs may be one hour or less.

[0172] In the fifth aspect above, according to the eleventh aspect, the oxidizing agent may be divided and introduced at a rate of 0.001 mol / min to 0.02 mol / min based on the molar amount of iron contained in the electrode powder.

[0173] In any one of the first to eleventh aspects above, according to the twelfth aspect, the electrode powder contains lithium, and the carbon dioxide can be introduced at a rate of 0.5 L / min to 4.5 L / min per 1g of lithium contained in the electrode powder.

[0174] In any one of the first to twelfth aspects above, according to the twelfth aspect, the solvent may comprise an aqueous solvent in which strong acids are excluded.

[0175] In the fifth aspect above, according to the 14th aspect, a solid containing iron may be produced in the step of producing the lithium precursor solution.

[0176] In the above 14th aspect, according to the 15th aspect, a step of solid-liquid separation of the solid containing iron may be further included.

[0177] In any one of the first to fifth aspects above, according to the sixth aspect, the step of heat-treating the lithium precursor solution may be further included.

[0178] In any one of the first to sixth aspects above, according to the seventh aspect, the oxidizing agent may include one or more of hydrogen peroxide, ozone water, perbromic acid, perchloric acid, and periodic acid.

[0179]

[0180]

[0181] Hereinafter, experimental examples including specific embodiments and comparative examples are presented to aid in understanding the present disclosure; however, these are merely illustrative of the present disclosure and are not intended to limit the appended claims. It is obvious to those skilled in the art that various changes and modifications to the embodiments are possible within the scope and spirit of the present disclosure, and that such variations and modifications fall within the scope of the appended claims.

[0182]

[0183] Examples and Comparative Examples

[0184] Example 1

[0185] After discharging the cells separated from the spent lithium iron phosphate battery, they were cut and crushed into units of several centimeters to obtain black powder containing lithium iron phosphate (LiFePO4) as electrode powder. 20g of the black powder and 185g of distilled water (H2O) were mixed.

[0186] Carbon dioxide was injected into the mixed solution at an injection rate of 2 L / min per 0.9 g of lithium in the black powder, and 30% hydrogen peroxide (H2O2) was added at equal amounts at 15-minute intervals for 2 hours to leach lithium, thereby producing a leachate as a lithium precursor solution. Hydrogen peroxide was added such that the ratio of the total moles of hydrogen peroxide to the total moles of iron in the black powder was 1.25.

[0187] Afterwards, lithium carbonate (Li2CO3) was recovered as a lithium precursor by heating to about 80°C.

[0188] The probe of an ORP (Oxidation-Reduction Potential) meter (Mettler Toledo ORP meter (reference electrode Ag / AgCl)) was inserted into the leaching solution to check the oxidation atmosphere of the leaching solution over time. The potential values ​​measured by the ORP meter based on Ag / AgCl were converted to the standard hydrogen electrode (SHE) standard using the instrument program.

[0189] In addition, the weights of lithium, iron, and phosphorus contained in the leaching solution over time were determined using an ICP-OES analyzer (Inductively Coupled Plasma-Optical Emission Spectroscopy, Agilent 5800). The ICP-OES analysis was performed by sampling and analyzing the leaching solution.

[0190] The leaching rate was calculated from the ICP analysis results, and the leaching rate was calculated according to Equation 2 below.

[0191] [Equation 2]

[0192] Leaching rate (%) = (Weight of elements contained in the leaching solution (lithium precursor solution) after time / Weight of elements contained in the black powder (electrode powder)) * 100

[0193] The results of the analysis of the hydrogen peroxide injection interval, injection amount, ORP of the leaching solution, and ICP of the leaching solution according to Example 1 are shown in Table 1 below.

[0194] Time Elapsed (min) Whether Water Was Added ORP Elemental Concentration in Leachate (Wt%) Leaching Rate (%) mV LiFe P LiFe P 0 O-------15 O 2 25.10.14 0.01 20.03 5 29.8 0.31.73 0 O 2 2 30.23 0.015 0.04 2 49.0 0.4 2.14 5 O 2 16.2 0.3 0.019 0.04 6 3.9 0.5 2.06 0 O 2 11.10.37 0.02 20.04 57 8.90.62.275O207.70.410.0250.04787.40.72.390O209.70.4390.0260.04793.60. 72.3105O209.40.4390.0270.0593.60.72.5120X210.50.4380.030.05293.40.82.6

[0195]

[0196] Example 2

[0197] A lithium precursor was recovered by the same method as in Example 1, except that the number of times, intervals, and amount of hydrogen peroxide were added were changed so that the ratio of the total moles of hydrogen peroxide added to the total moles of iron in the black powder was 0.75. The number of times, intervals, and amount of hydrogen peroxide added, as well as the ORP of the leaching solution and the ICP of the leaching solution analysis results according to Example 2, are shown in Table 2 below.

[0198] Time Elapsed (min) Whether Water Was Added ORP Elemental Concentration in Leachate (Wt%) Leaching Rate (%) mV LiFe P LiFe P 0 O-------15 O 2 2.7 0.1 2 0.01 1 0.03 4 2 5.6 0.3 1.73 0 O 2 9.3 0.19 0.01 3 0.03 7 4 0.5 0.4 1.84 5 O 2 5.1 0.27 0.01 6 0.03 9 5 7.6 0.4 1.96 0 O 2 1 6.5 0.3 2 0.01 9 0.04 168.20.52.075O214.20.370.0210.04378.90.62.190X2120.4110.0230.04487.60.6 2.2105X216.40.4280.0230.04791.20.62.3120X214.90.4350.0230.04692.70.62.3

[0199]

[0200] Example 3

[0201] A lithium precursor was recovered by the same method as in Example 1, except that the number of times, intervals, and amount of hydrogen peroxide were added were changed so that the ratio of the total moles of hydrogen peroxide added to the total moles of iron in the black powder was 0.5. The number of times, intervals, and amount of hydrogen peroxide added, as well as the ORP of the leaching solution and the ICP of the leaching solution analysis results according to Example 3, are shown in Table 3 below.

[0202] Time Elapsed (min) Whether Water Was Added ORP Elemental Concentration in Leachate (Wt%) Leaching Rate (%) mV LiFe P LiFe P 0 O-------15 O 13 5.3 0.0 8 10.0 11 0.0 3 17.3 0.3 1.5 30 O 23 9.2 0.1 5 0.0 12 0.0 3 4 32.0 0.3 1.7 45 O 23 8.9 0.1 9 0.0 13 0.0 3 6 4 0.5 0.4 1.8 60 O 23 7.8 0.2 4 0.0 1 50 .03251.20.41.675O233.20.290.0170.03861.80.51.990O2320.330.0190.0470.3 0.52.0105X227.80.350.0180.04474.60.52.2120X2240.360.0190.04276.70.52.1

[0203]

[0204] Example 4

[0205] A lithium precursor was recovered by the same method as in Example 1, except that the number of times, intervals, and amount of hydrogen peroxide were added were changed within the range where the ratio of the total moles of hydrogen peroxide added to the total moles of iron in the black powder was maintained at 1.25. The number of times, intervals, and amount of hydrogen peroxide added, as well as the ORP of the leaching solution and the ICP of the leaching solution analysis results according to Example 4, are shown in Table 4 below.

[0206] Time Elapsed (min) Whether Water Was Added ORP Elemental Concentration in Leachate (Wt%) Leaching Rate (%) mV LiFe P LiFe P 0 O -------15 X 2 1 1.4 0.3 1 0.0 2 0.0 43 6 6.1 0.5 2.13 0 X 2 3.5 0.3 3 0.0 2 1 0.0 47 7 0.3 0.6 2.34 5 X 2 3.2 0.3 3 0.0 2 1 0.0 47 7 0.3 0.6 2.36 0 O 2 0 2.8 0.3 4 0.0 2 2 0.0 4 972.50.62.475X209.50.40.0280.0585.30.82.590X208.20.4310.0330.05191.90. 92.5105X2100.4420.0320.05394.20.92.6120X212.20.4480.0310.05695.50.82.8

[0207]

[0208] Example 5

[0209] A lithium precursor was recovered by the same method as in Example 1, except that hydrogen peroxide was added at a constant rate for 2 hours within a range where the ratio of the total moles of hydrogen peroxide added to the total moles of iron in the black powder was maintained at 1.25. Based on the ratio of the total moles of hydrogen peroxide added to the total moles of iron in the black powder, hydrogen peroxide was added at a rate of 0.01 mol / min, and the ORP of the leaching solution and the ICP of the leaching solution analysis results are shown in Table 5 below.

[0210] Time (min) ORP Elemental Concentration in Leachate (Wt%) Leaching Rate (%) m VLiFePLiFeP0-------15 211.00.30 0.02 0.04 36 3.9 0.5 2.13 0 213.00.35 0.02 20.04 77 4.6 0.6 2.34 5 212.5 0.38 0.02 10.04 88 1.00.6 2.46 0 210.2 0.4 20.02 10.04 889.50.62.475209.90.440.0250.04993.80.72.490209.50.450.0260.0595.90.72.5105210.10.460.0280.05198.10.82.5120208.60.460.0300.05398.10.82.6

[0211]

[0212] Comparative Example 1

[0213] The lithium precursor was recovered by the same method as in Example 1, except that hydrogen peroxide was added all at once. The ORP of the leaching solution and the ICP of the leaching solution according to Comparative Example 1 are shown in Table 6 below.

[0214] Time Elapsed (min) Whether Water Was Added ORP Elemental Concentration in Leachate (Wt%) Leaching Rate (%) mV LiFe PL iFe P 0 O -------7 X 20 70.2 20.0 15 0.0 44 6.9 0.4 2.0 13 X 19 0.3 5 0.0 25 0.0 48 74.6 0.7 2.4 35 X -0.3 6 0.0 26 0.0 47 76.7 0.7 2.3 59 X 16 5.5 0.3 7 0.0 27 0.0 47 78.9 0.7 2.3 93 X 16 1.7 0.3 7 0.0 27 0.0 46 78.9 0.7 2.3 12 4 X 15 9.8 0.3 8 0.0 28 0.0 46 81.0 0.8 2.3

[0215]

[0216] Comparative Example 2

[0217] A lithium precursor was recovered by the same method as in Example 1, except that the number of times, intervals, and amount of hydrogen peroxide were added were adjusted within a range where the ratio of the number of moles of hydrogen peroxide to the number of moles of iron in the black powder was maintained at 0.75, and the ORP range was changed. The number of times, intervals, and amount of hydrogen peroxide added, as well as the ORP of the leaching solution and the ICP analysis results of the leaching solution according to Comparative Example 2, are shown in Table 7 below.

[0218] Time Elapsed (min) Whether Water Was Added ORP Elemental Concentration in Leachate (Wt%) Leaching Rate (%) mV LiFe P LiFe P 0 O-------30 X 2 19.7 0.25 0.01 70.046 5 3.3 0.5 2.36 0 O 20 0.2 0.26 0.01 70.045 5 5.4 0.5 2.29 0 X 2 14.4 0.35 0.02 40.049 74.6 0.7 2.41 20 X 17 1.1 0.4 10.02 40.05 48 7.4 0.7 2.7

[0219]

[0220] Experimental Example. Evaluation of Lithium Recovery Rate

[0221] The lithium recovery rate of the process according to the examples and comparative examples was measured. The lithium recovery rate was calculated according to Equation 3 below from the weight of lithium contained in the black powder and the weight of lithium contained in the recovered lithium precursor. The weight of lithium contained in the black powder and the weight of lithium contained in the recovered lithium precursor were measured using the ICP-OES analyzer.

[0222] [Equation 3]

[0223] Lithium Recovery Rate (%) = (Weight of lithium contained in recovered lithium precursor / Weight of lithium contained in black powder (electrode powder)) * 100

[0224] The calculation results of the lithium recovery rate according to Equation 3 above are shown in Table 8 below.

[0225] Classification Lithium Recovery Rate (%) Example 191.5 Example 288.3 Example 372.5 Example 492.6 Example 595.4 Comparative Example 178.2 Comparative Example 281.3

[0226] Referring to Table 8 above, the lithium recovery rate was improved in the lithium precursor recovery process according to the examples.

[0227] In Example 3, where the content of hydrogen peroxide introduced was reduced, the lithium recovery rate decreased.

[0228] In the lithium precursor recovery process according to Comparative Example 1, in which hydrogen peroxide was introduced all at once, the lithium recovery rate decreased. In Comparative Example 2, in which the ORP of the leaching solution was reduced, the lithium recovery rate decreased.

Claims

1. A step of forming an electrode powder solution by adding electrode powder and carbon dioxide to a solvent; and The method includes the step of generating a lithium precursor solution by adding an oxidizing agent in portions to the electrode powder solution. A lithium precursor recovery method wherein the change rate of the Oxidation-Reduction Potential (ORP) of the lithium precursor solution calculated by the following Equation 1 is 80% or more: [Equation 1] ORP Change Rate (%) = (In Equation 1, O i represents the initial ORP value measured 30 minutes after the start of the addition of the oxidizing agent to the electrode powder solution, and O f represents the late ORP value measured at a time when 120 minutes have elapsed from the time the oxidizing agent was introduced into the electrode powder solution, and O i and O f is based on a value converted based on the standard hydrogen electrode (SHE).

2. A method for recovering a lithium precursor according to claim 1, wherein the ORP change rate of the lithium precursor solution is 90% or more.

3. A method for recovering a lithium precursor according to claim 1, wherein the ORP value of the lithium precursor solution is maintained at 200 mV or higher in the step of generating the lithium precursor solution.

4. A method for recovering a lithium precursor according to claim 3, wherein the ORP value of the lithium precursor solution is maintained at 200 mV to 1,770 mV.

5. A method for recovering a lithium precursor according to claim 1, wherein the electrode powder comprises iron.

6. A method for recovering a lithium precursor according to claim 5, wherein the oxidizing agent is divided and added six or more times.

7. A method for recovering a lithium precursor according to claim 6, wherein the molar ratio of the oxidizing agent to the iron contained in the electrode powder is 0.4 to 1.

0.

8. A method for recovering a lithium precursor according to claim 6, wherein the time interval between the divided inputs is 30 minutes or less.

9. A method for recovering a lithium precursor according to claim 5, wherein the molar ratio of the oxidizing agent to the iron contained in the electrode powder is 1.0 to 1.5, and the oxidizing agent is added in 2 to 5 divided portions.

10. A method for recovering a lithium precursor according to claim 9, wherein the time interval between the divided inputs is 1 hour or less.

11. A method for recovering a lithium precursor according to claim 5, wherein the oxidizing agent is divided and introduced at a rate of 0.001 mol / min to 0.02 mol / min based on the molar amount of iron contained in the electrode powder.

12. A method for recovering a lithium precursor according to claim 1, wherein the electrode powder contains lithium, and the carbon dioxide is introduced at a rate of 0.5 L / min to 4.5 L / min per 1 g of lithium contained in the electrode powder.

13. A method for recovering a lithium precursor according to claim 1, wherein the solvent comprises an aqueous solvent from which strong acids are excluded.

14. A method for recovering a lithium precursor according to claim 5, wherein a solid containing iron is produced in the step of producing the lithium precursor solution.

15. A method for recovering a lithium precursor according to claim 14, further comprising the step of solid-liquid separation of the solid containing iron.

16. A method for recovering a lithium precursor according to claim 1, further comprising the step of heat-treating the lithium precursor solution.

17. A method for recovering a lithium precursor according to claim 1, wherein the oxidizing agent comprises one or more of hydrogen peroxide, ozone water, perbromic acid, perchloric acid, and periodic acid.

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