Compositions including lithium-containing compounds and methods for treating batteries

Abstract

Regarding a lithium compound for valuable metal recovery and a recovery method thereof, the recovery method for the lithium compound for valuable metal recovery includes the steps of preparing a battery, freezing and forcibly discharging the battery, crushing the battery, and heating the crushed battery material, wherein the heating step is performed at a temperature range of 1,100 to 1,400°C and the degree of vacuum (LogP [atm]) during the heating step is performed in the range of -4 to 0, and the lithium compound recovered through the heating step contains impurities, which may include, in weight percent, Na: 1.8 wt% or less (excluding 0 wt%), K: 0.06 wt% or less (excluding 0 wt%), Ca: 0.62 wt% or less (excluding 0 wt%), and Mg: 0.47 wt% or less (excluding 0 wt%).

Description

[Technical Field]

[0001] The present invention relates to waste batteries, and to a composition comprising a lithium-containing compound extracted from recycled waste batteries, and a method for treating batteries. [Background technology]

[0002] As the demand for electric vehicles increases worldwide, the disposal of waste batteries from these vehicles has become a social issue. Lithium secondary batteries, which are the main raw materials for such waste batteries, contain organic solvents, explosives, and heavy metals such as Ni, Co, Mn, and Fe. Ni, Co, Mn, and Li are highly valuable as valuable metals, and therefore, the recovery and recycling process of discarded lithium secondary batteries has emerged as an important research field.

[0003] Specifically, a lithium secondary battery mainly comprises copper and aluminum used as a current collector, an oxide containing Li, Ni, Co, and Mn that constitutes the cathode material, and graphite used as the anode material, a separator that separates the cathode material from the anode material, and an electrolyte that is poured into the separator. The solvent and salt that constitute the electrolyte are typically a mixture of carbonate organic compounds such as ethylene carbonate and propylene carbonate, e.g., LiPF6.

[0004] In order to utilize the waste batteries, active development has been made into a waste battery recycling process in which the waste batteries are crushed to generate intermediate materials such as waste battery crushed materials or black powder, and valuable metals are recovered through post-processing.

[0005] However, in the waste battery recycling process, although the waste batteries vary depending on the number of times they have been used and their condition, they generally have a voltage in the range of 3.0 to 3.2 V in a fully discharged state per cell and a voltage close to 4 V in a fully charged state. In modules or packs in which tens to hundreds of cells are connected, such residual voltages have a very large amount of energy, so when the waste batteries are physically disassembled by applying an external impact to them, safety issues arise regarding battery explosion and electric shock.

[0006] To prevent this, after disassembly, holes are created in the battery and it is discharged with salt water. After the discharge is complete, the battery is crushed and then subjected to high-temperature heat treatment to remove water and electrolyte.

[0007] The salt used in the saltwater discharge contains large amounts of substances such as Na, K, Cl, Mg, and Ca. Of these substances, Cl in particular is partially removed during high-temperature heat treatment, but the crushed waste batteries and the black powder, which is a powder mixture of Ni-Co-Mn-Li-O oxide and C obtained by further processing the crushed waste batteries to remove Al, Cu, and part of the separator, contain impurities such as Na, K, and Mg.

[0008] The impurities are extracted using acid leaching in the post-process of waste battery recycling. After Ni-Co-Mn is recovered, Li is recovered using the residual acid leaching solution. This process dilutes the Li concentration, resulting in a lower recovery rate. Therefore, research into methods to resolve this issue is needed.

[0009] In addition, while lithium fluoride (LiF) and lithium carbonate (Li2CO3) are water-soluble among Li-containing materials, oxides such as LiAlO2-Li5AlO4 are not, and when these compounds are mixed, it is necessary to maximize the recovery of lithium-containing materials by using acid leaching using sulfuric acid rather than water leaching. However, there are problems with the amount of Li compounds produced at high temperatures varying, and the loss of Li due to the vaporization of LiF(g) reducing the Li recovery rate, so research is needed into process conditions that can maximize the recovery of Li compounds. Summary of the Invention [Problem to be solved by the invention]

[0010] A composition including a lithium-containing compound according to one embodiment of the present invention provides a composition that can efficiently recover lithium-containing materials, thereby minimizing LiF vaporization and maximizing the LiAlO-LiAlO ratio.

[0011] In accordance with another embodiment of the present invention, a method for recovering lithium compounds provides a method for recovering compounds with the advantages described above. [Means for solving the problem]

[0012] According to one embodiment of the present invention, the composition containing a lithium-containing compound is a composition containing LiAlO2 and at least one of Li2CO3, LiF, and Li5AlO4, and the content of LiAlO2 may be 12% or more based on 100% by weight of the total. In one embodiment, the composition containing a lithium-containing compound may be recovered from waste batteries.

[0013] In one embodiment, the Li2CO3 may be 30% or less, the LiF may be 30% or less, and the Li5AlO4 may be 40% or less by weight. In one embodiment, the total content of Li2CO3 and LiF may be 50% or less.

[0014] In one embodiment, the composition including the lithium-containing compound can include a lithium-containing compound satisfying Formula 1 below. <Expression 1> 3.0≦([LiAlO2]+[Li5AlO4]) / ([LiF]+[Li2CO3]))≦10.0 ([LiAlO2], [Li5AlO4], [LiF], and [Li2CO3] represent the crystalline phase fractions of LiAlO2, Li5AlO4, LiF, and Li2CO3, respectively.)

[0015] In one embodiment, the composition including the lithium-containing compound can satisfy the following formula 2: <Expression 2> 0.1≦I A / I B ≦1.5 (I A is the peak intensity value of the LiAlO2 product at 2θ=21°±0.5°, and I B (means the peak intensity value of the LiAlO2 product at 2θ=32.6°±0.4°)

[0016] In one embodiment, the composition including the lithium-containing compound can satisfy the following formula 3: <Expression 3> [Al] = 0.3702 × [Li] + 0.0832 ± 0.5 ([Al] and [Li] mean the number of moles of Al and Li, respectively.)

[0017] According to another embodiment of the present invention, a battery treatment method includes the steps of preparing a battery, crushing the battery into crushed battery fragments, and subjecting the crushed battery fragments to a high-temperature heat treatment, the high-temperature heat treatment being performed at a temperature in the range of 1,100 to 1,500°C and in a gas atmosphere having an oxygen concentration in the range of 0.4 to 0.8%. In one embodiment, the step of preparing the battery includes a step of freezing the battery, and the step of freezing the battery satisfies the following formula 4: <Expression 4> Minimum cooling time (Hr)=A×(W 0.33 ) (A=4×e (-0.02×dT) ,W=battery weight (kg), dT=|external cooling temperature - target temperature|, || means absolute value)

[0018] In one embodiment, the step of freezing the battery can include a step of cooling the battery to −150° C. to −20° C. In one embodiment, the step of preparing the battery can include a step of performing forced discharge.

[0019] In one embodiment, the battery treatment method may further include a step of separating the nickel alloy by magnetic separation after the high-temperature heat treatment, and then obtaining a composition containing a remaining lithium compound. In one embodiment, the acidic solution may have a pH of 4 or less.

[0020] In one embodiment, the composition including the lithium compound obtained through high-temperature heat treatment may have a leaching rate of 95% or more in an acidic solution of pH 4 or less. In one embodiment, in the battery treatment method, the composition including the lithium compound obtained through high-temperature heat treatment may satisfy the following formula 1: <Expression 1> 3.0≦([LiAlO2]+[Li5AlO4]) / ([LiF]+[Li2CO3]))≦10 ([LiAlO2], [Li5AlO4], [LiF], and [Li2CO3] refer to the crystalline phase fractions of LiAlO2, Li5AlO4, LiF, and Li2CO3, respectively.)

[0021] In one embodiment, the lithium compound obtained through high-temperature heat treatment may satisfy the following formula 3: <Expression 3> [Al] = 0.3702 × [Li] + 0.0832 ± 0.5 ([Al] and [Li] mean the number of moles of Al and Li, respectively.) [Effects of the Invention]

[0022] According to one embodiment of the present invention, by controlling the content ratio of the compound in the lithium-containing material according to the temperature, oxygen, and maintenance time, a lithium-containing compound with excellent stability at high temperatures is secured, and a lithium-containing compound with excellent lithium recovery rate is provided.

[0023] A method for recovering lithium-containing compounds according to another embodiment of the present invention provides a method for recovering lithium-containing compounds having the advantages described above. [Brief explanation of the drawings]

[0024] [Figure 1] 4 is a graph illustrating the change in battery voltage as a function of coolant temperature according to one embodiment of the present invention. [Figure 2] 1 is a graph showing the relationship between battery weight, external cooling temperature, and cooling time according to an embodiment of the present invention. [Figure 3A] This is a photograph showing a fire that occurred when the product was crushed after being frozen for a shorter time than the minimum cooling time according to a comparative example of the present invention. [Figure 3B] This is a photograph showing a fire that occurred when the product was crushed after being frozen for a shorter time than the minimum cooling time according to a comparative example of the present invention. [Figure 3C] 10 is a photograph of an example in which no fire occurred when crushed after being frozen for a period longer than the minimum cooling time according to an example of the present invention. [Figure 3D] 10 is a photograph of an example in which no fire occurred when crushed after being frozen for a period longer than the minimum cooling time according to an example of the present invention. [Figure 4] 1 shows the LiF(g) partial pressure change during a high temperature heat treatment step according to one embodiment of the present invention. [Figure 5] 1 shows the content ratio of LiAlO2 and Li5AlO4 as a function of oxygen content under the condition of a high temperature heat treatment step at 1600°C according to an embodiment of the present invention. [Figure 6] 1 shows a Li-Al-HOEH-pH diagram according to one embodiment of the present invention. [Figure 7]1 shows a graph for deriving a relationship depending on the molar ratio of Li and Al in a Li—Al—O compound according to one embodiment of the present invention. [Figure 8] 1 is an XRD analysis result of a lithium compound according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] Terms such as first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited thereto. These terms are used only to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Thus, a first part, component, region, layer, or section described below can be referred to as a second part, component, region, layer, or section without departing from the scope of the present invention.

[0026] The terminology used herein is for the purpose of referring to particular embodiments only and is not intended to limit the present invention. As used herein, the singular forms "a," "an," and "the" include the plural forms unless the context clearly dictates otherwise. As used in the specification, the term "comprising" refers to the inclusion of particular features, regions, integers, steps, operations, elements, and / or components, and does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and / or components.

[0027] When a part is described as being "on" or "above" another part, it is above the other part, and there may be other parts between them. In contrast, when a part is described as being "directly on" another part, there are no other parts between them.

[0028] In addition, % in this specification means % by weight unless otherwise specified.

[0029] Unless otherwise defined, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by a person of ordinary skill in the art to which this invention belongs. Commonly used predefined terms are additionally interpreted to have a meaning consistent with the relevant technical literature and the presently disclosed content, and are not interpreted in an ideal or very formal sense unless defined.

[0030] Hereinafter, embodiments of the present invention will be described in detail, but these are presented as examples and are not intended to limit the present invention, which is defined only by the scope of the claims set forth below.

[0031] A composition according to one embodiment of the present invention includes a lithium-containing compound. Specifically, the lithium-containing compound includes lithium aluminum oxide. The lithium-containing compound includes a lithium-containing compound produced by the battery treatment method described below, such as one recovered from used batteries. The lithium aluminum oxide may be LiAlO2 or Li5AlO4, for example, LiAlO2. In one embodiment, the lithium-containing compound may further include at least one of Li2CO3, LiF, and Li5AlO4.

[0032] The LiAlO2 may be contained in an amount of 12% or more based on 100% by weight of the entire composition. Specifically, the LiAlO2 may be contained in an amount of 45%, more specifically, 70% or more.

[0033] The LiAlO2 content within the above range has the advantage of ensuring stable products under high temperature and oxygen concentration atmosphere and increasing the lithium recovery yield. If the high temperature and oxygen concentration atmosphere are not appropriate, LiF will be lost due to vaporization, or a large amount of compounds such as Li2CO3 or LiF, which are difficult to recover due to water solubility, will be produced, resulting in a decrease in lithium recovery rate.

[0034] In one embodiment, Li2CO3 may be contained in an amount of 30% or less based on 100% by weight of the total composition. The Li2CO3 may be contained in an amount of 15.0% or less, more specifically, 5% or less. By ensuring that the Li2CO3 content satisfies the above range, there is an advantage in preventing the large amount of compounds that are difficult to recover due to water solubility issues from being produced.

[0035] In one embodiment, LiF may be contained in an amount of 30 wt% or less based on 100 wt% of the total composition. The LiF may be contained in an amount of 19 wt%, specifically 17 wt% or less based on 100 wt% of the total composition. By ensuring that the LiF content satisfies the above range, it is possible to prevent the large amount of compounds that are difficult to recover due to water solubility issues from being produced.

[0036] In one embodiment, the total content of Li2CO3 and LiF may be 50% or less by weight. Specifically, the total content may be 0.5 to 50%, more specifically, the total content may be 0.5 to 30%. By having the total amount of Li2CO3 and LiF satisfy the above range, it is possible to prevent the large amount of compounds that are difficult to recover due to water solubility problems from being produced, and it is possible to appropriately control the high temperature and oxygen concentration to produce a large amount of stable compounds that have excellent sulfuric acid leaching rates, thereby improving the efficiency of lithium recovery.

[0037] In one embodiment, the composition including the lithium-containing compound can satisfy the following formula 1: <Expression 1> 3.0≦([LiAlO2]+[Li5AlO4]) / ([LiF]+[Li2CO3]))≦10.0 ([LiAlO2], [Li5AlO4], [LiF], and [Li2CO3] refer to the crystalline phase fractions of LiAlO2, Li5AlO4, LiF, and Li2CO3, respectively.)

[0038] The formula 1 is a relational expression for the crystalline phase ratio of the lithium-containing compound in the composition containing the lithium-containing compound, which is a reactant produced through a high-temperature reduction reaction described below. The formula 1 may satisfy 3.0 to 10.0, specifically 3.60 to 7.50, and more specifically 3.64 to 7.07.

[0039] By satisfying the above formula 1, the composition containing the lithium-containing compound of the present invention has the advantage of promoting the formation of crystalline phases of LiAlO2 and Li5AlO4, thereby improving the lithium recovery rate. If the content of the above formula 1 is not satisfied, specifically, if the content is lower than the content of the above formula 1, there is a problem that the lithium recovery rate decreases as LiF evaporates.

[0040] In one embodiment, the composition including the lithium-containing compound can satisfy the following formula 2: <Expression 2> 0.1 A / I B <1.5 (In the above formula 2, I A is the peak intensity value of the LiAlO2 product at 2θ=21°±0.5°, and I B is the peak intensity value of the LiAlO2 product at 2θ=32.6°±0.4°)

[0041] The above formula 2 is a relational expression for the ratio of peak intensity values ​​at a specific angle of LiAlO2, which is a lithium oxide in a composition containing a lithium-containing compound, which is a reactant produced through a high-temperature reduction reaction described below. The above formula 2 can satisfy 0.1 to 1.5, specifically 0.3 to 1.5, and more specifically 0.7 to 1.3.

[0042] ​In one embodiment, LiAlO2 may have at least one of XRD peaks at 20.5-21.5°, 29.0-29.5°, 31.5-32.0°, 32.2-33.0°, 60.5-61.5°, and 70.0-72.0°. Li5AlO4 may have at least one of XRD peaks at 19.5-20.2° and 21.6-22.2°. LiF compositions may have at least one of XRD peaks at 37.5-40.2°, 43.9-46.5°, and 64.5-66.5°. Li2CO3 compositions may have at least one of XRD peaks at 24.0-26.0°, 27.0-29.0°, 34.0-36.0°, and 37.0-39.0°.

[0043] In one embodiment, the composition including the lithium-containing compound can satisfy the following formula 3: <Expression 3> [Al] = 0.3702 × [Li] + 0.0832 ± 0.5 ([Al] and [Li] mean the number of moles of Al and Li, respectively.)

[0044] It was confirmed through Equation 3 that elements such as Li and Al, which have strong oxidizing power at high temperatures, produce reaction products such as LiAlO2 or Li5AlO4, which are stable at high temperatures. Equation 3 may fall within the range of [Al] = 0.3702 × [Li] + 0.5832 as an upper limit and [Al] = 0.3702 × [Li] - 0.4168 as a lower limit. Failure to satisfy Equation 3 may result in a decrease in the production of lithium aluminum oxide, which has strong oxidizing power at high temperatures.

[0045] According to another embodiment of the present invention, a battery processing method includes the steps of preparing a battery, crushing the battery into battery fragments, and subjecting the crushed battery fragments to high-temperature heat treatment.

[0046] In the step of preparing the battery, the method for processing various types of batteries including lithium ion batteries may be, for example, a lithium secondary battery separated from an automobile or a secondary battery separated from an electronic device such as a mobile phone, a camera, or a laptop computer, specifically a lithium secondary battery. More specifically, the battery utilizes waste batteries, which has the advantage of being environmentally friendly.

[0047] In one embodiment, the step of preparing the battery may include a step of freezing the battery, which is a step for stabilizing the electrolyte in the battery and has the advantage of reducing the risk of fire during the battery crushing step described below.

[0048] In one embodiment, the step of freezing the battery may satisfy the following formula 4: <Expression 4> Minimum cooling time (Hr)=A×(W 0.33 ) (A=4×e (-0.02×dT) ,W=battery weight (kg), dT=|external cooling temperature - target temperature|, || means absolute value)

[0049] In Equation 4, W represents the weight of the battery, e.g., the weight of a battery pack, a single battery, or a combination thereof. The minimum cooling time represents the external cooling temperature applied to the battery, e.g., the target temperature for cooling the electrolyte in the battery.

[0050] The step of freezing the battery has an advantage that the electrolyte inside the battery is cooled by performing the step of freezing the battery for a minimum cooling time or more, thereby enabling subsequent processes to be performed stably. However, if the step of freezing the battery is performed for a time shorter than the minimum cooling time, the electrolyte is not cooled, which may pose a risk of fire when the battery is crushed.

[0051] The step of freezing the battery is carried out at a temperature sufficient to freeze the electrolyte contained in the battery. Specifically, the freezing step can be carried out at a temperature range of, for example, −150 to −20° C. More specifically, the temperature range is −150 to −50° C., and even more specifically, the temperature range is −80 to −60° C.

[0052] When the battery is frozen within the above temperature range, the slight voltage remaining inside the battery, for example, about 2 V to 3 V, drops to nearly 0 V. As a result, even if a short circuit occurs due to direct contact between the positive and negative electrodes, no battery reaction occurs, so the battery temperature does not increase and gas generation and combustion of the electrolyte do not occur. Furthermore, because the electrolyte is in a frozen state or a state in which vaporization is suppressed, the mobility of lithium ions is very low, significantly reducing the current-carrying properties due to the lithium ion migration, and vaporization of the electrolyte does not occur, so flammable gases such as ethylene, propylene, and hydrogen are not generated.

[0053] If the freezing process is performed outside the above temperature range, for example, at a temperature higher than -60°C, the remaining voltage inside the battery will not drop to 0V, which may cause a battery reaction due to a short circuit, and the electrolyte will not be completely frozen, making this unsuitable. Furthermore, if the battery is cooled to -150°C, the electrolyte will be sufficiently frozen and the internal voltage of the battery will also drop to 0V, so there is no need to lower the temperature below this. Thus, by including a step of freezing batteries, such as lithium secondary batteries, before crushing them, the battery disposal method advantageously prevents the risk of fire that may occur during the battery crushing process.

[0054] The step of crushing the battery may refer to a step of applying impact or pressure to the battery so that a portion of the battery separates from the battery. In one embodiment, the step of crushing the battery may refer to a step of crushing the battery, a step of cutting the battery, a step of compressing the battery, and combinations thereof. Specifically, the step of crushing may include any step of breaking the battery to obtain small pieces.

[0055] In one embodiment, the step of crushing the battery may include all of the steps of crushing the prepared battery by compressing the battery or applying an external force such as a shear force or a tensile force, etc. The step of crushing the battery may be performed using, for example, a crusher.

[0056] In one embodiment, the step of crushing the battery can be performed at least once or more times. Specifically, the step of crushing the battery can be performed at least once or more times continuously or discontinuously.

[0057] In one embodiment, the step of crushing the battery can be performed under conditions of supplying an inert gas, carbon dioxide, nitrogen, water, or a combination thereof, or under a vacuum atmosphere of 100 torr or less. For example, when the freezing step of the battery is performed by cooling at a temperature range of −60 to −20° C., when performed under the above conditions, the supply of oxygen can be suppressed to prevent the electrolyte from reacting with oxygen, thereby preventing an explosion, and the vaporization of the electrolyte can be suppressed to prevent the generation of flammable gases such as ethylene, propylene, or hydrogen.

[0058] In one embodiment, the step of crushing the battery may be performed so that the maximum size of the crushed battery fragments is 100 mm or less. Specifically, the size of the crushed battery fragments may be 50 mm or less. If the maximum size of the crushed battery fragments is 100 mm or more, as the crushed battery fragments are crushed, the heat generated due to instability may rise to a temperature range of 120°C, which is the average vaporization temperature of the electrolyte, and stability issues such as fire may occur.

[0059] In one embodiment, the step of preparing the battery may include a step of forcibly discharging the battery. The forcible discharge may involve electrically discharging the battery, and may involve reducing the voltage to less than 3.2 V using a reverse voltage, thereby reducing the voltage to nearly 0 V. For example, if the battery is subjected to the forcible discharge after the step of freezing the battery, problems such as electrolyte evaporation during discharge can be prevented when the battery is to be crushed.

[0060] The high-temperature heat treatment of the crushed battery fragments may involve placing the crushed battery fragments in a furnace capable of raising the temperature to a temperature equal to or higher than the melting point of the crushed battery fragments. The high-temperature heat treatment may involve heat treatment conditions for performing a high-temperature reduction reaction on the battery fragments without melting the battery fragments.

[0061] In one embodiment, the step of subjecting the crushed battery material to high-temperature heat treatment can be performed at a temperature in the range of 1100 to 1500° C. Specifically, the step of subjecting the crushed battery material to high-temperature heat treatment can be performed at a temperature in the range of 1300 to 1500° C.

[0062] If the temperature is outside the upper limit of the range, lithium may be lost due to lithium evaporation, whereas if the temperature is outside the lower limit of the range, sintering and reduction of the alloying elements may not proceed smoothly, making it impossible to form a stabilized lithium-containing compound, which may make it difficult to recover the stabilized compound in the future.

[0063] In one embodiment, the high-temperature heat treatment of the crushed battery material can be performed in an atmosphere of at least one gas selected from the group consisting of an inert gas, carbon dioxide, carbon monoxide, a hydrocarbon gas, and oxygen. The inert gas may include at least one of argon and nitrogen. The reduction reaction of the crushed battery material in the gas atmosphere can advantageously increase the recovery rate of valuable metal elements contained in the crushed battery material.

[0064] In one embodiment, the step of subjecting the crushed battery material to high-temperature heat treatment can be performed in a gas atmosphere containing at least one of an inert gas, carbon dioxide, carbon monoxide, and a hydrocarbon gas; and oxygen. In one embodiment, the step can be performed in a gas atmosphere having an oxygen concentration in the range of 0.4 to 0.8 vol%. Specifically, the step can be performed in a gas atmosphere having an oxygen concentration in the range of 0.4 to 0.6%. As the oxygen concentration increases, the Li2O+C+O2(g)=Li2CO3 reaction is promoted while LiAlO2 and Li5AlO4 are reduced. Therefore, it is preferable that the oxygen concentration be within the aforementioned range.

[0065] Furthermore, as the temperature rises, Li5AlO4 is produced through the reaction LiAlO2(s) + 2Li2CO3(s) = Li5AlO4 + 2CO2(g), and since the LiF(g) vaporization reaction is promoted, the reaction temperature is preferably in the range of 1,000 to 1,500°C. If the oxygen concentration in the gas is outside the upper limit, excessive carbon dioxide is formed during the reduction reaction and is gasified and lost along with lithium, or Li2CO3(s) is produced in such an excessive amount that it is difficult to recover by acid leaching.

[0066] In one embodiment, the step of subjecting the crushed battery to high-temperature heat treatment may satisfy the following formula 4:

[0067] In one embodiment, the battery processing method may include a step of separating the nickel alloy by magnetic separation after the high-temperature heat treatment step, and then obtaining a composition containing a lithium compound. Specifically, after the high-temperature heat treatment step, the composition containing the lithium compound and a powder containing the nickel alloy, e.g., black powder, may be obtained. The nickel alloy contained in the black powder may be separated by magnetic separation to separate the composition containing the lithium compound.

[0068] In one embodiment, the battery treatment method may further include recovering lithium by leaching the composition containing the lithium compound with an acidic solution, wherein the acidic solution may have a pH of 4 or less.

[0069] If the pH is 4 or higher, the stabilized lithium-containing compound may not achieve the desired precipitation rate. The acidic solution may be, for example, sulfuric acid. Specifically, the composition containing the lithium compound may be leached with the acidic solution to dissolve metals, such as aluminum, in the lithium compound, thereby recovering lithium.

[0070] In one embodiment, the leachability of the composition including the lithium-containing compound in sulfate may be 95% or greater. Specifically, the leachability of the composition including the lithium-containing compound in sulfate may be 96% or greater.

[0071] Advantageously, by increasing the leaching rate of the composition containing the lithium-containing compound, the lithium recovery rate can be maximized. [Example]

[0072] Preferred examples and comparative examples of the present invention will be described below. However, the following examples are preferred embodiments of the present invention, and the present invention is not limited to the following examples.

[0073] <Battery internal temperature according to minimum freezing time> The battery pack used in the example was crushed without freezing using the same crusher as in the example. During the crushing process, a flame occurred due to a short circuit, as shown in Figure 6.

[0074] As described above, through Example 1 and Comparative Example 1, it can be confirmed that by including a step of freezing the battery pack including the battery before crushing the battery, no short circuit occurs and no flame occurs during the battery crushing step, resulting in excellent stability.

[0075] FIG. 1 is a graph illustrating the variation of battery voltage as a function of cooling temperature, according to one embodiment of the present invention.

[0076] 1, it can be seen that a battery processing method according to an embodiment of the present invention can derive a minimum cooling time for cooling the battery in the step of freezing the battery. Specifically, it can be seen that the minimum cooling time is related to the battery weight, the external cooling temperature, and the target temperature.

[0077] FIG. 2 is a graph showing the relationship between battery weight, external cooling temperature, and cooling time according to one embodiment of the present invention.

[0078] Referring to Figure 2, the external cooling temperature and minimum cooling time are shown when the target temperature is set to -70°C and the battery weights are 2.5 kg (A), 10 kg (B), 20 kg (C), and 50 kg (D). When cooling the battery, the battery electrolyte begins to cool after a predetermined time, and it can be seen that the voltage becomes 0. This confirms that a minimum maintenance time is required to sufficiently cool the battery's interior, specifically the electrolyte.

[0079] Specifically, in the heat transfer situation for cooling where heat is taken away to the outside, when the specific heat of the battery itself is taken into account, it can be confirmed that the battery weight and cooling time are required.

[0080] Even in the case of heat transfer for cooling where heat is taken away from the outside, it can be seen that the battery weight and cooling time are required when considering the specific heat of the battery itself.

[0081] In this way, in the present invention, the minimum time required for cooling the battery can be confirmed using the external cooling temperature for refrigeration, the target temperature, and the battery weight.

[0082] Table 1 below lists the minimum cooling time depending on the battery weight and external cooling temperature.

[0083] [Table 1]

[0084] Table 1 shows that the smaller the battery weight, the shorter the minimum cooling time required for the battery to be cooled. It can also be seen that when the battery is cooled for the minimum cooling time derived from the relationship between the battery weight, external cooling temperature, and target temperature, the battery, specifically the battery electrolyte, is cooled. Furthermore, when the battery is cooled for a time longer than the minimum cooling time listed in Table 1, no fire occurs during the subsequent battery crushing process. Figures 3A and 3B are photographs of a comparative example of the present invention in which a fire occurred when the battery was crushed after being frozen for a shorter time than the minimum cooling time. Figures 3C and 3D are photographs of an example of the present invention in which a fire did not occur when the battery was crushed after being frozen for a longer time than the minimum cooling time. Figures 3A and 3B show an experiment to determine the fire occurrence status of crushed batteries when the battery was frozen for a time shorter than the minimum cooling time required. In the experiment, when the battery weight was 25 kg, the external cooling temperature was -95°C, and the target freezing temperature was -70°C, the minimum cooling time, which is the value of Equation 4 below, was 7 hours. The experiment was conducted for 5 hours, which is shorter than the minimum cooling time. <Expression 4> Minimum cooling time = A × (W 0.33 ) (A=4×e (-0.02×dT) ,W=battery weight (kg), dT=|external cooling temperature - target temperature|, || means absolute value)

[0085] 3C and 3D show an experiment on the fire occurrence state of crushed batteries when the batteries were frozen for more than the minimum freezing time required for cooling. The experiment was conducted with the same battery weight, external cooling temperature, and minimum freezing time as in Figures 3A and 3B, and was conducted for more than 7 hours.

[0086] Table 2 below compares the fire occurrence status between the Example and Comparative Example, with the same battery weight, external cooling temperature, and minimum freezing time, as shown in Figures 3A to 3D. The fire occurrence status was judged as "○" if a fire was observed after the battery was crushed, and "×" if not.

[0087] [Table 2]

[0088] From Table 2, it can be seen that if the battery is cooled at a value smaller than the value of Equation 4, which corresponds to the minimum cooling time, the electrolyte will not be cooled down, resulting in a fire occurring after the battery is crushed. Thus, it can be seen that if the battery is cooled using the value of Equation 4 as the minimum cooling time, the crushed battery can be stably utilized without the risk of fire occurring after being crushed.

[0089] <High-temperature heat treatment step - amount of Li compounds produced depending on temperature> During the high-temperature heat treatment, a reduction reaction occurs, producing reaction products such as LiAlO2, Li2CO3, LiF, and Li5AlO4. Specifically, the reaction products are produced according to the following reaction formulas 1 to 6. [Reaction Equation 1] Li2O(s) + Al2O3(s) = 2LiAlO2(s) [Reaction Equation 2] 5 / 2Li2O(s) + 1 / 2Al2O3(s) = Li5AlO4(s) [Reaction 3] Li2O(s) + C(s) + O2(g) = Li2CO3(s) [Reaction 4] Li2O(s) + 2F(l) = 2LiF(s) + 1 / 2O2(g) [Reaction 5] LiPF6(l) + H2O(l) = 2HF(g) + POF3(g) + LiF(s) [Reaction 6] LiAlO2(s) + 2Li2CO3(s) = Li5AlO4(s) + 2CO2(g) The amounts of reaction products generated by the above reactions 1 to 6 may vary depending on the temperature and oxygen concentration. Tables 3 to 7 below show the amounts of reaction products as a function of the heat treatment temperature when the oxygen concentration is 0.4 vol%, 0.6 vol%, 0.8 vol%, 1.0 vol%, and 1.2 vol%, respectively.

[0090] [Table 3]

[0091] [Table 4]

[0092] [Table 5]

[0093] [Table 6]

[0094] [Table 7]

[0095] From Tables 3 to 7, it can be seen that as the heat treatment temperature increases under the same oxygen concentration conditions, the LiF concentration increases and then suddenly decreases. Specifically, as the heat treatment temperature increases, the amount of LiF produced decreases as LiF is partially gasified at 1,300°C. More specifically, at 1,600°C, the LiF content is zero. Under the same oxygen concentration, excessively increasing the temperature results in LiF vaporization, making it difficult to secure the amount of LiF produced and reducing the lithium recovery rate. Therefore, under the same oxygen concentration, a heat treatment temperature of 1,500°C or less can suppress LiF vaporization and increase the lithium recovery rate. Furthermore, Tables 3 to 5 show that, under the same temperature conditions, increasing the oxygen concentration promotes the formation of Li5AlO4. In contrast, Tables 6 and 7 show that when the oxygen partial pressure is 1.0% or higher, the formation of Li2CO3 is stabilized, resulting in a decrease in the total amount of LiAlO2-Li5AlO4 produced.

[0096] FIG. 4 shows the LiF(g) partial pressure change during the high temperature heat treatment step according to one embodiment of the present invention. As can be seen from Figure 4, the vaporization of LiF increases as the temperature rises during the high-temperature heat treatment step. Specifically, above 1,300°C, it can be seen that lithium recovery is difficult due to the vaporization of LiF.

[0097] From Tables 3 to 7 and Figure 4, it was confirmed that when the high-temperature heat treatment process is performed at 1,100°C or higher, specifically 1,300°C or higher, LiF and Li2CO3 are minimized and Li5AlO4 and LiAlO2 are maximized. Thus, it was confirmed that when the high-temperature heat treatment step is performed at a temperature range of 1,100 to 1,500°C in a gas atmosphere with an oxygen concentration of 0.4 to 0.8%, LiF vaporization is suppressed and the formation of LiAlO2 and Li5AlO4 is promoted.

[0098] Table 8 below shows the content ratio of LiAlO2 and Li5AlO4 according to the oxygen content under the high temperature heat treatment step conditions of 1,600°C.

[0099] [Table 8]

[0100] Figure 5 shows the LiAlO2 and Li5AlO4 content ratios as a function of oxygen content under a high-temperature heat treatment step at 1600°C according to one embodiment of the present invention. Table 8 and Figure 5 show that the amount of Li5AlO4 produced increases as the oxygen content increases under the same temperature conditions. Furthermore, when comparing the sulfuric acid leaching rates of LiAlO2 and Li5AlO4 mixtures produced under the same temperature conditions, the leaching rates were found to be similar even when the Li5AlO4 content was high. Because the leaching rates were similar, it was determined that conditions were needed to primarily produce LiAlO2 or Li5AlO4 while suppressing LiF vaporization.

[0101] <Li-Al-H2OのEH-pHタイアグラム(Pourbaix Diagram)> FIG. 6 shows a Li-Al-H2OEH-pH diagram according to one embodiment of the present invention. The EH-pH time series is a graph showing the relationship between the potential and pH at which metals and metal ions in an aqueous solution are thermodynamically stable. The EH-pH time series in Figure 6 was measured at 25°C. As shown in Figure 6, the standard electrode potential of Al is -1.66, and that of Li is -3.04. Under strong acid conditions with a pH of 4 or less, such as sulfuric acid, the potential is -0.2 V or less. + and Al 3+ It was confirmed that it exists as an ion. Specifically, in the case of compounds Li2O and Al2O3, the Li and Al ions are easily ionized in strong acids with low pH, such as sulfuric acid, to form SO4 2-It shows a form that easily forms a complex, and it can be confirmed that the leaching rate is high regardless of the type of compound. Also, in the high-temperature heat treatment step, it was confirmed that by raising the temperature, a large amount of Li was lost due to the large generation corresponding to the vaporization of LiF(g). Thereby, in order to promote the formation of LiAlO2 and Li5AlO4 and improve the actual yield of Li while suppressing the vaporization of LiF, it was confirmed that it is preferable to perform high-temperature heat treatment at 1500 °C or lower.

[0102] <Relationship formula of Li-Al-O compound> FIG. 7 shows a graph for deriving a relational expression according to the molar ratio of Li and Al in a Li-Al-O compound according to an embodiment of the present invention. Looking at FIG. 7, when the battery is heat-treated at a high temperature after going through a freezing step at an extremely low temperature, it can be confirmed that for the Li-Al-O compound generated at 900 °C or higher, the molar ratio between Li and Al satisfies the following relational expression. <Relational expression> [Al] = 0.3702 × [Li] + 0.0832 ± 0.5 ([Al] and [Li] respectively mean the number of moles of Al and Li) Through the above relational expression, it was confirmed that elements having a strong oxidizing power at high temperatures, such as Li and Al, produce reaction products such as LiAlO2 or Li5AlO4 that are stable at high temperatures. Thus, during high-temperature heat treatment, the reaction between the Al cover or Al current collector of the LiB battery and Li in the positive electrode material stably occurs according to the above relational expression, and by satisfying the above relational expression, it was confirmed that there is an advantage that the Li recovery rate can be improved.

[0103] <Analysis of the generated lithium compound> Analysis of the components and crystal phase ratio of the lithium compound As shown in Table 9 below, it was confirmed that the components and crystalline phase ratios were varied by controlling the temperature and oxygen concentration in the high-temperature heat treatment step of the present invention. The crystalline phase ratios were analyzed based on quantitative XRD results and represent the ratios when the crystalline phase is taken as 100%, and can be determined in the same way as weight percent.

[0104] [Table 9]

[0105] Table 9 above confirms that when the temperature and oxygen concentration in the high-temperature heat treatment step of the present invention are controlled within the ranges of the present invention, the formation of LiAlO2 and Li5AlO4 is promoted, the vaporization of LiF is suppressed, and the Li recovery rate is improved. Specifically, Experimental Examples 1 to 3 and Comparative Example 1 confirm that when the oxygen concentration is lower than 1.0 vol%, the formation of LiAlO2 and Li5AlO4 is promoted. Furthermore, Experimental Examples 1 to 3 and Experimental Examples 4 to 6 confirm that the vaporization of LiF is suppressed, and the Li recovery rate is improved.

[0106] Analysis of lithium compound components and crystalline phase ratios FIG. 8 shows an XRD analysis of a lithium compound according to one embodiment of the present invention. Figure 8 shows the composition and XRD analysis results of the lithium compounds produced after high-temperature heat treatment at 1,300°C of crushed material obtained by cryogenic freeze crushing without saltwater discharge. It was confirmed that the lithium compounds produced after high-temperature heat treatment consisted of crystalline phases, LiAlO2, Li2CO3, or LiF, with LiAlO2 accounting for more than 12% of the crystalline phase.

[0107] Table 10 below shows the components and XRD analysis results of the lithium compounds produced when the oxygen concentration was controlled based on the temperatures of 1,100° C. and 1,500° C. Specifically, Table 10 below shows the XRD peak values ​​of the experimental examples and comparative examples in Table 9 above.

[0108] [Table 10]

[0109] From Table 10, it was confirmed that the intensity ratio I(A) / I(B) of the XRD peak values ​​was within the range of 0.1 to 1.5. For a detailed explanation of the intensity ratio, please refer to the above description. Although the preferred embodiments have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concepts defined in the following claims also fall within the scope of the present invention.

Claims

1. LiAlO ２ and Li ２ CO ３ , LiF, and Li ５ AlO ４ A composition containing a lithium compound containing at least one of The LiAlO ２ The content of the lithium-containing compound is 12% or more based on 100% by weight of the total.

2. The composition containing a lithium-containing compound according to claim 1 , wherein the composition containing a lithium-containing compound is recovered from waste batteries.

3. The Li in wt. ２ CO ３ is 30% or less, LiF is 30% or less, and Li ５ AlO ４ The composition comprising the lithium-containing compound according to claim 1, wherein the ratio of the total amount of the lithium-containing compound to the total amount of the lithium-containing compound is 40% or less.

4. Li ２ CO ３ and LiF, the total content of which is 50% or less.

5. A composition comprising the lithium-containing compound according to claim 1, which satisfies the following formula 1: <Formula 1> 3.0≦([L-A-O ２ ]+[L- ５ A-O ４ ]) / ([LF]+[[F ２ CO ３ ]))≦10.0 ([LiAlO ２ ], [Li ５ AlO ４ ], [LiF], and [Li ２ CO ３ ] are LiAlO ２ , Li ５ AlO ４ , LiF, and Li ２ CO ３ (meaning the crystalline phase ratio of

6. A composition comprising the lithium-containing compound according to claim 1, which satisfies the following formula 2: <Formula 2> 0.1≦I Ａ / I Ｂ ≦1.5 (I Ａ is LiAlO ２ is the peak intensity value of the product at 2θ=21°±0.5°, and I Ｂ is LiAlO ２ (This means the peak intensity value of the product at 2θ = 32.6° ± 0.4°)

7. A composition comprising the lithium-containing compound according to claim 1, which satisfies the following formula 3: <Formula 3> [Al]=0.3702×[Li]+0.0832±0.5 ([Al] and [Li] mean the number of moles of Al and Li, respectively.)

8. preparing a battery; shredding the battery into battery shreds; and A step of subjecting the crushed battery fragments to high-temperature heat treatment; The high-temperature heat treatment step is carried out at a temperature in the range of 1,100 to 1,500°C; A battery treatment method carried out in a gas atmosphere having an oxygen concentration in the range of 0.4 to 0.8%.

9. preparing the battery includes freezing the battery; 9. The battery treatment method according to claim 8, wherein the step of freezing the battery satisfies the following formula 4: <Formula 4> Minimum cooldown time (Hr) = A × (W) ０．３３ ) (A = 4 × e （－０．０２×ｄＴ） , W = battery weight (kg), dT = |external cooling temperature-target temperature|, || means absolute value)

10. 10. The battery treatment method according to claim 9, wherein the step of freezing the battery is performed by cooling the battery to -150°C to -20°C.

11. The step of preparing a battery includes:

9. The battery treatment method of claim 8, further comprising the step of performing a forced discharge.

12. 9. The method of claim 8, further comprising the step of: separating the nickel alloy by magnetic separation after the high-temperature heat treatment, and then obtaining a composition containing the remaining lithium compound.

13. 13. The battery treatment method of claim 12, further comprising leaching the composition comprising the lithium compound with an acidic solution to recover the lithium.

14. The battery treatment method of claim 13, wherein the acidic solution has a pH of 4 or less.

15. 14. The method of claim 13, wherein the composition containing the lithium compound obtained through the high-temperature heat treatment has a leaching rate of 95% or more in an acidic solution of pH 4 or less.

16. 9. The battery treatment method of claim 8, wherein the composition containing the lithium compound obtained through the high-temperature heat treatment satisfies the following formula 1: <Formula 1> 3.0≦([L-A-O ２ ]+[L- ５ A-O ４ ]) / ([LF]+[[F ２ CO ３ ]))≦10 ([LiAlO ２ ], [Li ５ AlO ４ ], [LiF], and [Li ２ CO ３ ] are LiAlO ２ , Li ５ AlO ４ , LiF, and Li ２ CO ３ (meaning the crystalline phase ratio of

17. 9. The method of claim 8, wherein the lithium compound obtained through the high-temperature heat treatment satisfies the following formula 3: <Formula 3> [Al]=0.3702×[Li]+0.0832±0.5 ([Al] and [Li] mean the number of moles of Al and Li, respectively.)

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