Composition comprising lithium-containing compound and battery processing method

Abstract

The present invention relates to a lithium compound for valuable metal recovery and a method for recovering the same. The method for recovering a lithium compound for valuable metal recovery comprises: a step for preparing a battery; freezing and forcibly discharging the battery; a step of crushing the battery; and a step of heating the crushed battery product, the heating step being carried out at a temperature in the range of 1100 to 1400 DEG C, the heating step being carried out at a vacuum degree (LogP [standard atmospheric pressure]) in the range of-4 to 0, the lithium compound recovered by the heating step containing impurities, in wt%, the content of the impurities in the crushed battery product being less than or equal to 1% by weight, and the content of the impurities in the crushed battery product being less than or equal to 1% by weight, and the content of the impurities in the crushed battery product being less than or equal to 1% by weight. The impurities may include 1.8 wt% or less and 0 wt% excluding Na, 0.06 wt% or less and 0 wt% excluding K, 0.62 wt% or less and 0 wt% excluding Ca, and 0.47 wt% or less and 0 wt% excluding Mg.

Description

Technical Field

[0001] The present invention relates to waste batteries, and in particular to a composition containing lithium compounds extracted from the waste batteries for recycling and a battery treatment method. Background Art

[0002] As the global demand for electric vehicles grows, how to deal with the waste batteries generated by these vehicles has become a social issue. Lithium secondary batteries, which are the main raw materials of the waste batteries, contain organic solvents, explosive substances and heavy metal substances such as Ni, Co, Mn and Fe, but Ni, Co, Mn and Li are valuable metals with great scarcity value. The recycling and reuse process of discarded lithium secondary batteries has become an important research field.

[0003] Specifically, the lithium secondary battery is mainly composed of copper and aluminum used as collectors, oxides containing Li, Ni, Co, and Mn constituting positive electrode materials, and graphite used as negative electrode materials, and includes a separator for isolating the positive electrode material and the negative electrode material and an electrolyte injected into the separator. The solvent (Solvent) constituting the electrolyte and the solvent used as the salt (Salt) are mainly mixed with carbonate organics such as ethylene carbonate (Ethylene Carbonate) and propylene carbonate (Propylene Carbonate), for example, LiPF6 is used.

[0004] In order to utilize the waste batteries, a waste battery recycling process is currently being actively developed, which is used to crush the waste batteries to produce intermediate materials such as waste battery crushed materials or black powder, and then recover valuable metals through subsequent processes.

[0005] However, in the waste battery recycling process, for the waste batteries, although it varies depending on the number of times the battery is used or the state, generally each battery has a voltage in the range of 3.0 to 3.2V in a fully discharged state, and has a voltage close to 4V in a fully charged state. Therefore, a module or battery pack connected with dozens to hundreds of batteries has a considerable amount of energy in these residual voltages, so when an external impact is applied to the waste batteries for physical decomposition, there are safety issues related to battery explosion or electric shock.

[0006] In order to prevent the above situation, after the decomposition, the battery is punched and placed in salt water for discharge. The battery after the discharge is crushed and then subjected to high temperature heat treatment to remove water and electrolyte.

[0007] At this time, the salt used for the salt water discharge contains a large amount of substances such as Na, K, Cl, Mg and Ca. Among the aforementioned substances, Cl is removed to a certain extent during the high temperature heat treatment process, but the crushed material of the waste battery or the further processed crushed material to remove Al, Cu and the oxide of Ni-Co-Mn-Li-O of part of the diaphragm and the powdery powder mixed with C, that is, the black powder, contains substances such as Na, K and Mg as impurities.

[0008] Because of the impurities, there is the following problem: in the waste battery recycling process, due to the process characteristics of recovering Li from the residual acid leaching solution after recovering Ni-Co-Mn in the subsequent acid leaching extraction process, the Li concentration is diluted, resulting in a decrease in the recovery rate. Therefore, it is necessary to study a method for solving the above problem.

[0009] In addition, among lithium-containing substances, lithium fluoride (LiF) and lithium carbonate (Li2CO3) are water-soluble, but oxides such as LiAlO2-Li5AlO4 are not water-soluble, so when these compounds are mixed, it is necessary to use acid leaching using sulfuric acid to maximize the recovery of lithium-containing substances instead of using water leaching. However, lithium compounds are generated in different amounts at high temperatures, and there is a problem that the lithium recovery rate is reduced due to lithium loss caused by the gasification of LiF(g), so it is necessary to study the process conditions that can maximize the recovery of lithium compounds. Summary of the invention

[0010] Technical issues to be solved

[0011] According to one embodiment of the present invention, a composition comprising a lithium-containing compound is provided, which can effectively recover lithium-containing substances, minimize LiF gasification, and maximize the ratio of LiAlO2-Li5AlO4.

[0012] According to another embodiment of the present invention, a lithium compound recovery method is provided for recovering compounds having the aforementioned advantages.

[0013] Technical Solution

[0014] According to one embodiment of the present invention, the composition containing a lithium-containing compound is a composition containing a lithium compound, wherein the lithium compound includes LiAlO2; and at least any one of Li2CO3, LiF and Li5AlO4, and the content of the LiAlO2 may be greater than 12% based on the total 100 weight%.

[0015] In one embodiment, the composition comprising a lithium-containing compound may be recovered from waste batteries.

[0016] In one embodiment, in terms of weight %, the content of Li2CO3 may be less than 30%, the content of LiF may be less than 30%, and the content of Li5AlO4 may be less than 40%. In one embodiment, the total content of Li2CO3 and LiF may satisfy less than 50%.

[0017] In one embodiment, the composition including the lithium-containing compound may include a lithium-containing compound satisfying Formula 1 below.

[0018] <Formula 1>

[0019] 3.0≤([LiAlO2]+[Li5AlO4]) / ([LiF]+[Li2CO3]))≤10.0

[0020] [LiAlO2], [Li5AlO4], [LiF] and [Li2CO3] represent the crystal phase ratios of LiAlO2, Li5AlO4, LiF and Li2CO3, respectively.

[0021] In one embodiment, the composition including the lithium-containing compound may satisfy Formula 2 below.

[0022] <Formula 2>

[0023] 0.1≤I A / I B ≤1.5

[0024] I A The peak intensity value of LiAlO2 product at 2θ = 21° ± 0.5°, I B The peak intensity value of 2θ=32.6°±0.4° for the LiAlO2 product is shown.

[0025] In one embodiment, the composition including the lithium-containing compound may satisfy Formula 3 below.

[0026] <Formula 3>

[0027] [Al]=0.3702×[Li]+0.0832±0.5

[0028] [Al] and [Li] represent the moles of Al and Li, respectively.

[0029] According to another embodiment of the present invention, a battery processing method may include: a step of preparing a battery; a step of crushing the battery into battery fragments; and a step of performing high-temperature heat treatment on the crushed battery fragments, wherein the high-temperature heat treatment step may be performed at a temperature range of 1100 to 1500°C and in a gas environment with an oxygen concentration in the range of 0.4 to 0.8%.

[0030] In one embodiment, the step of preparing the battery includes the step of freezing the battery.

[0031] The step of freezing the battery satisfies the following formula 4.

[0032] <Formula 4>

[0033] Minimum cooling time (hours) = A × (W0.33)

[0034] A=4×e(-0.02×dT), W=battery weight (Kg), dT=│external cooling temperature-target temperature│, ││ represents absolute value.

[0035] In one embodiment, the step of freezing the battery may include a step of cooling the battery to -150°C to -20°C.

[0036] In one embodiment, the step of preparing the battery may include the step of performing a forced discharge.

[0037] In one embodiment, the battery treatment method may further include, after the high temperature heat treatment step, a step of obtaining a composition comprising a lithium compound remaining after the nickel alloy is separated by magnetic screening. In one embodiment, the acidic solution may satisfy a pH of 4 or less.

[0038] In one embodiment, the composition containing a lithium compound obtained by high temperature heat treatment may have a leaching rate of 95% or more in an acidic solution with a pH of 4 or less. In one embodiment, in a battery treatment method, the composition containing a lithium compound obtained by high temperature heat treatment may satisfy the following formula 1.

[0039] <Formula 1>

[0040] 3.0≤([LiAlO2]+[Li5AlO4]) / ([LiF]+[Li2CO3]))≤10

[0041] [LiAlO2], [Li5AlO4], [LiF] and [Li2CO3] represent the crystal phase ratios of LiAlO2, Li5AlO4, LiF and Li2CO3, respectively.

[0042] In one embodiment, the lithium compound obtained by high temperature heat treatment may satisfy Formula 3 below.

[0043] <Formula 3>

[0044] [Al]=0.3702×[Li]+0.0832±0.5

[0045] [Al] and [Li] represent the moles of Al and Li, respectively.

[0046] Beneficial Effects

[0047] According to one embodiment of the present invention, by controlling the content ratio of the compound in the lithium-containing substance based on temperature, oxygen and retention time, a lithium-containing compound with excellent stability at high temperature is ensured, thereby providing a lithium-containing compound with excellent lithium recovery rate.

[0048] According to another embodiment of the present invention, a method for recovering lithium-containing compounds provides a method for recovering lithium-containing compounds having the aforementioned advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a graph showing a battery voltage change based on a cooling temperature according to an embodiment of the present invention.

[0050] Figure 2 is a graph showing the relationship among battery weight, external cooling temperature, and cooling time according to one embodiment of the present invention.

[0051] Figure 3a and Figure 3b is a photograph showing a fire that occurred when a comparative example of the present invention was broken after being frozen (the time is shorter than the minimum cooling time), Figure 3c and Figure 3d This is a photograph of an embodiment according to the present invention in which no fire occurred when the sample was crushed after being frozen (for a period longer than the minimum cooling time).

[0052] Figure 4 The change in the partial pressure of LiF(g) during the high temperature heat treatment step according to one embodiment of the present invention is shown.

[0053] Figure 5 The content ratio of LiAlO2 and Li5AlO4 based on the oxygen content under the high temperature heat treatment step condition of 1600°C according to one embodiment of the present invention is shown.

[0054] Figure 6 An EH-pH diagram of Li—Al—H 2 O according to one embodiment of the present invention is shown.

[0055] Figure 7 A graph is shown for deriving a relational expression based on the molar ratio of Li and Al in a Li—Al—O compound according to an embodiment of the present invention.

[0056] Figure 8 is an XRD analysis result of a lithium compound according to an embodiment of the present invention. DETAILED DESCRIPTION

[0057] The composition according to one embodiment of the present invention comprises a lithium-containing compound. Specifically, the lithium-containing compound comprises lithium aluminum oxide. The lithium-containing compound comprises a lithium-containing compound generated by the following battery treatment method, such as a lithium-containing compound recovered from a waste battery. The lithium aluminum oxide may be LiAlO2 or Li5AlO4, such as LiAlO2. In one embodiment, the lithium-containing compound may also comprise at least one of Li2CO3, LiF and Li5AlO4.

[0058] Based on 100 wt % of the total composition, the LiAlO2 may contain 12% or more, specifically, 45%, and more specifically, 70% or more.

[0059] By satisfying the aforementioned range of the content of LiAlO2, a stable product is ensured under a high temperature and reasonable oxygen concentration environment, thereby having the advantage of being able to improve the actual recovery rate of lithium. If the high temperature and oxygen concentration environment are not suitable, the loss of Li caused by the gasification of LiF or the water solubility of Li2CO3 or LiF leads to the generation of a large amount of compounds that are difficult to recover, resulting in a problem of reduced lithium recovery rate.

[0060] In one embodiment, based on 100 wt % of the total composition, Li2CO3 may contain 30% or less. The Li2CO3 may contain 15.0% or less, and more specifically, may contain 5% or less. By satisfying the aforementioned range of the content of the Li2CO3, there is an advantage of preventing the water solubility problem from causing a large amount of compounds that are difficult to recover.

[0061] In one embodiment, based on 100 wt % of the total composition, LiF may include 30 wt % or less. Based on 100 wt % of the total composition, the LiF may include 19 wt %, specifically 17 wt % or less. By satisfying the aforementioned range of the content of the LiF, there is an advantage of preventing the water solubility problem from causing a large amount of compounds that are difficult to recycle.

[0062] In one embodiment, the total content of Li2CO3 and LiF may be less than 50% by weight. Specifically, the total content may be 0.5 to 50%, and more specifically, the content may be less than 0.5 to 30%. By ensuring that the total content of Li2CO3 and LiF meets the aforementioned range, it is possible to prevent the water solubility problem from causing a large amount of compounds that are difficult to recover, and to reasonably adjust the high temperature and oxygen concentration to generate a large amount of stable compounds with excellent leaching rate in sulfuric acid, thereby having the advantage of high lithium recovery efficiency.

[0063] In one embodiment, the composition including the lithium-containing compound may satisfy Formula 1 below.

[0064] <Formula 1>

[0065] 3.0≤([LiAlO2]+[Li5AlO4]) / ([LiF]+[Li2CO3]))≤10.0

[0066] [LiAlO2], [Li5AlO4], [LiF] and [Li2CO3] represent the crystal phase ratios of LiAlO2, Li5AlO4, LiF and Li2CO3, respectively.

[0067] The above formula 1 is a relationship formula for the crystal phase ratio of the lithium-containing compound in the reactant (i.e., the composition containing the lithium-containing compound) generated by the following high-temperature reduction reaction. The above formula 1 may satisfy 3.0 to 10.0, specifically 3.60 to 7.50, and more specifically 3.64 to 7.07.

[0068] By satisfying the above formula 1, the composition containing the lithium-containing compound of the present invention promotes the formation of LiAlO2 and Li5AlO4 crystal phases, thereby having the advantage of improving the actual yield of lithium. If the content of the above formula 1 is not satisfied, specifically, if it has a value lower than the content of the above formula 1, there is a problem of decreased actual yield of lithium due to LiF gasification.

[0069] In one embodiment, the composition including the lithium-containing compound may satisfy Formula 2 below.

[0070] <Formula 2>

[0071] 0.1〈I A / I B 〈1.5

[0072] In the above formula 2, I A The peak intensity value of LiAlO2 product at 2θ = 21° ± 0.5°, I B The peak intensity value of 2θ=32.6°±0.4° for the LiAlO2 product is shown.

[0073] The above formula 2 is a relationship formula for the ratio of the peak intensity values ​​of lithium oxide LiAlO2 at a specific angle in the reactant (i.e., the composition containing the lithium compound) generated by the following high-temperature reduction reaction. 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.

[0074] In one embodiment, for LiAlO2, as an XRD peak, at least one of 20.5 to 21.5°, 29.0 to 29.5°, 31.5 to 32.0°, 32.2 to 33.0°, 60.5 to 61.5°, and 70.0 to 72.0° may be included. For Li5AlO4, as an XRD peak, at least one of 19.5 to 20.2° and 21.6 to 22.2° may be included. For LiF compositions, as an XRD peak, at least one of 37.5 to 40.2°, 43.9 to 46.5°, and 64.5 to 66.5° may be included. For Li2CO3 compositions, as an XRD peak, at least one of 24.0 to 26.0°, 27.0 to 29.0°, 34.0 to 36.0°, and 37.0 to 39.0° may be included.

[0075] In one embodiment, the composition including the lithium-containing compound may satisfy Formula 3 below.

[0076] <Formula 3>

[0077] [Al]=0.3702×[Li]+0.0832±0.5

[0078] [Al] and [Li] represent the moles of Al and Li, respectively.

[0079] It is confirmed by the above formula 3 that elements such as Li and Al that have strong oxidizing power at high temperatures generate stable reaction products such as LiAlO2 or Li5AlO4 at high temperatures. The above formula 3 may be within the range of [Al] = 0.3702 × [Li] + 0.5832 as the upper limit and [Al] = 0.3702 × [Li] - 0.4168 as the lower limit. If the above formula 3 is not satisfied, there will be a problem that the generation of lithium aluminum oxide that has strong oxidizing power at high temperatures decreases.

[0080] According to another embodiment of the present invention, a battery processing method includes the steps of preparing a battery; crushing the battery into battery crushed objects; and performing a high-temperature heat treatment on the crushed battery crushed objects.

[0081] In the step of preparing the battery, the battery may be a battery processed by a method for processing various batteries containing lithium ions, and the battery may be, for example, a lithium secondary battery separated from a car, 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, since the battery utilizes waste batteries, it has the advantage of being environmentally friendly.

[0082] In one embodiment, the step of preparing the battery may include a step of freezing the battery. The step of freezing the battery is a step for stabilizing the electrolyte in the battery, which has the advantage of reducing the risk of fire in the following battery crushing step.

[0083] In one embodiment, the step of freezing the battery may satisfy the following formula 4.

[0084] <Formula 4>

[0085] Minimum cooling time (hours) = A × (W 0.33 )

[0086] A=4×e (-0.02×dT) , W = battery weight (Kg), dT = |external cooling temperature-target temperature|, ││ represents absolute value.

[0087] W in the above formula 4 represents the weight of the battery, for example, the weight of a battery pack, a single battery or a combination thereof. The minimum cooling time represents the time required for cooling the electrolyte in the battery to a target temperature by a cooling temperature (ie, an external cooling temperature) applied to the battery.

[0088] The step of freezing the battery is performed for more than the minimum cooling time, so that the electrolyte inside the battery is cooled, which has the advantage of being able to stably perform subsequent processes. In the step of freezing the battery, if the freezing time of the battery is less than the minimum cooling time, the electrolyte will not be cooled, and there is a risk of fire when it is broken.

[0089] 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. Specifically, the temperature range can be -150 to -50°C, more specifically, a temperature range of -80 to -60°C.

[0090] If the battery is frozen in the temperature range, the residual voltage inside the battery (e.g., about 2V to 3V) drops to nearly 0V, so even if a short circuit occurs where the positive and negative electrodes are in direct contact, a battery reaction does not occur, and the battery temperature does not increase, thereby preventing the generation of electrolyte gas and combustion. In addition, since the electrolyte is in a frozen state or a state where gasification is suppressed, the mobility of lithium ions is very low, and the power-on characteristics based on the migration of lithium ions may be significantly reduced. Since gasification of the electrolyte does not occur, the generation of combustible gases such as ethylene, propylene, and hydrogen can be avoided.

[0091] If the freezing process exceeds the temperature range, for example, it is cooled to a temperature higher than -60°C, the residual voltage inside the battery will not drop to 0V, a battery reaction caused by a short circuit may occur, and the electrolyte will not be completely frozen, so it is not suitable. In addition, when cooled to -150°C, the electrolyte will be fully frozen and the internal voltage of the battery will also drop to 0V, so there is no need to lower the temperature. As described above, the battery processing method has the following advantages: before crushing a battery such as a lithium secondary battery, a freezing step is included, thereby preventing the risk of fire that may occur in the battery crushing process.

[0092] The step of crushing the battery may refer to a process of applying an impact or compressive force to the battery to cause a portion of the battery to fall off. In one embodiment, the step of crushing the battery may refer to a process of crushing the battery, a process of cutting the battery, a process of compressing the battery, and a combination thereof. Specifically, the crushing step may include all processes that can destroy the battery to obtain small-sized crushed objects.

[0093] In one embodiment, the step of crushing the battery may include all processes of compressing the prepared battery or applying external force such as shear force or tensile force to destroy the battery. For example, the step of crushing the battery may be implemented using a crusher.

[0094] In one embodiment, the step of crushing the battery can be performed at least once. Specifically, the crushing step can be performed continuously or discontinuously at least once.

[0095] In one embodiment, the step of crushing the battery can be performed under the condition of supplying an inert gas, carbon dioxide, nitrogen, water or a combination thereof or under a vacuum environment condition of less than 100 Torr. For example, if the process of freezing the battery is performed by cooling to a temperature range of -60 to -20°C, if it is performed under the aforementioned conditions, the electrolyte can be prevented from reacting with oxygen by suppressing the supply of oxygen, and the explosion caused can be prevented, and the gasification of the electrolyte can be suppressed, thereby avoiding the generation of flammable gases such as ethylene, propylene or hydrogen.

[0096] In one embodiment, the step of crushing the battery can be implemented until the maximum size of the battery crushed object is less than 100 mm. Specifically, it can be implemented until the size of the battery crushed object is less than 50 mm. If the maximum size of the battery crushed object is more than 100 mm, as the battery crushed object is crushed, the heat temperature caused by instability will rise to the average vaporization temperature of the electrolyte (i.e., the temperature range of 120°C), thereby causing stability problems such as fire.

[0097] In one embodiment, the step of preparing the battery may include the step of performing forced discharge on the battery. The forced discharge is to discharge the battery and reduce the reverse voltage to below 3.2V, so that the voltage can be reduced to close to 0V. For example, after the step of freezing the battery, if the battery is crushed after the forced discharge, problems such as electrolyte gasification during discharge can be prevented.

[0098] In the step of subjecting the crushed battery fragments to high temperature heat treatment, the battery fragments are placed in a heating furnace that can be heated to a high temperature, so that the battery fragments can be heated to a temperature above the melting point. The high temperature heat treatment can be accompanied by a heat treatment condition for a high temperature reduction reaction of the battery without the need for a melting step.

[0099] In one embodiment, the step of subjecting the battery fragments to high temperature heat treatment may be performed at a temperature ranging from 1100 to 1500° C. Specifically, the step of subjecting the battery fragments to high temperature heat treatment may be performed at a temperature ranging from 1300 to 1500° C.

[0100] If the upper limit of the range is exceeded, there is a problem of lithium loss caused by lithium gasification. If the lower limit of the range is exceeded, the sintering and reduction of the alloying elements will not be carried out smoothly, and a stable lithium-containing compound will not be formed. Therefore, when the lithium compound is subsequently recovered, it is difficult to recover the stable compound.

[0101] In one embodiment, the step of subjecting the battery fragments to high temperature heat treatment can be performed in an environment of at least one of an inert gas, carbon dioxide, carbon monoxide, hydrocarbon gas, and oxygen. The inert gas may include, for example, at least one of argon and nitrogen. By performing the reduction reaction of the fragments in the gas environment, the recovery rate of the valuable metal elements contained in the battery fragments can be increased.

[0102] In one embodiment, the step of high-temperature heat treatment of the battery fragments can be performed in a gas environment containing at least one of an inert gas, carbon dioxide, carbon monoxide and a hydrocarbon gas; and oxygen. In one embodiment, it can be performed in a gas environment in which the oxygen concentration is in the range of 0.4 to 0.8 vol%. Specifically, it can be performed in a gas environment in which the oxygen concentration is in the range of 0.4 to 0.6%. The higher the oxygen range, the more it promotes the reaction of Li2O+C+O2(g)=Li2CO3, and there is a problem of reducing LiAlO2 and Li5AlO4, so it is preferably performed when the oxygen range is within the aforementioned range.

[0103] In addition, as the temperature rises, Li5AlO4 is generated by the reaction of LiAlO2(s)+2Li2CO3(s)=Li5AlO4+2CO2(g), but the gasification reaction of LiF(g) is promoted, and the reaction temperature is preferably carried out in the range of 1000 to 1500° C. If the oxygen concentration in the gas exceeds the upper limit, carbon dioxide is excessively formed during the reduction reaction and is lost by gasification with lithium, or Li2CO3(s) is excessively generated, which is difficult to recover by acid leaching.

[0104] In one embodiment, the step of subjecting the battery fragments to high temperature heat treatment may satisfy the following formula 4.

[0105] In one embodiment, for the battery treatment method, after the high-temperature heat treatment step, a step of obtaining a composition containing a lithium compound remaining after the nickel alloy is separated by magnetic screening may be included. Specifically, after the high-temperature heat treatment step, a composition containing a lithium compound and a powder containing a nickel alloy (such as black powder) may be included. The nickel alloy contained in the black powder is separated by magnetic screening, so that the composition containing a lithium compound can be separated.

[0106] In one embodiment, the battery treatment method may further include the step of leaching the composition containing the lithium compound with an acidic solution to recover lithium. The acidic solution may satisfy a pH value of 4 or less.

[0107] If the pH is above 4, there is a problem that the stable lithium-containing compound cannot ensure the target precipitation rate. For example, the acidic solution may be sulfuric acid. Specifically, the composition containing the lithium compound is leached with the acidic solution to dissolve metals such as aluminum in the lithium compound, thereby recovering lithium.

[0108] In one embodiment, the leaching rate of the composition containing the lithium compound in sulfuric acid may be 95% or more. Specifically, the leaching rate of the composition containing the lithium compound in sulfuric acid may be 96% or more.

[0109] By increasing the leaching rate of the composition comprising a lithium-containing compound, there is an advantage that the lithium recovery rate can be maximized.

[0110] The preferred embodiments and comparative examples of the present invention are described below. However, the following embodiment is only a preferred embodiment of the present invention, and the present invention is not limited to the following embodiment.

[0111] <Battery internal temperature based on minimum freezing time>

[0112] In the absence of freezing, the battery pack used in the embodiment is crushed using the same crusher as in the embodiment. Figure 6 As shown, a short circuit caused a flame during the crushing process.

[0113] As described above, it can be confirmed through Example 1 and Comparative Example 1 that since the step of freezing the battery pack including the battery is included before the battery crushing, short circuit and flame will not occur during the battery crushing step, and the battery has excellent stability.

[0114] Figure 1 is a graph showing a battery voltage change based on a cooling temperature according to an embodiment of the present invention.

[0115] Reference Figure 1 It can be confirmed that, for the battery processing method according to an embodiment of the present invention, in the step of freezing the battery, the minimum cooling time for cooling the battery can be derived. Specifically, it can be confirmed that the minimum cooling time is related to the battery weight, the external cooling temperature and the target temperature.

[0116] Figure 2 is a graph showing the relationship among battery weight, external cooling temperature, and cooling time according to one embodiment of the present invention.

[0117] Reference Figure 2 The figure shows the external cooling temperature and minimum cooling time when the target temperature is set to -70°C and the battery weights are 2.5kg (A), 10kg (B), 20kg (C) and 50kg (D). When cooling the battery, after a predetermined time, it can be confirmed that the electrolyte of the battery begins to cool and the voltage becomes 0. It can be confirmed that when cooling the battery, a minimum holding time is required to fully cool the inside (specifically the electrolyte).

[0118] Specifically, it can be confirmed that in the case of heat transfer for cooling (heat is taken to the outside), if the specific heat of the battery itself is taken into account, the battery weight and the time required for cooling are required. Even in the case of heat transfer for cooling (heat is taken to the outside), if the specific heat of the battery itself is taken into account, the battery weight and the time required for cooling are required.

[0119] As described above, in the present invention, in order to cool the battery, the minimum time required for cooling can be confirmed using the external cooling temperature and the target temperature for freezing and the battery weight.

[0120] The following Table 1 shows the minimum cooling time based on the battery weight and the external cooling temperature.

[0121]

Table 1

[0122]

[0123] It can be confirmed from Table 1 above that the smaller the battery weight, the shorter the minimum cooling time required for the battery to be cooled. In addition, when cooling is performed with the minimum cooling time derived from the relationship between the battery weight, the external cooling temperature and the target temperature, it can be confirmed that the battery is cooled, specifically, the electrolyte of the battery is cooled. In addition, when the battery is cooled for a time longer than the minimum cooling time shown in Table 1 above, no fire occurs during the battery crushing process in the subsequent process. Figure 3a and Figure 3b is a photograph showing a fire that occurred when a comparative example of the present invention was broken after being frozen (the time is shorter than the minimum cooling time), Figure 3c and Figure 3d This is a photograph of an embodiment of the present invention in which no fire occurs when the sample is crushed after being frozen (for a period longer than the minimum cooling time). Figure 3a and Figure 3b , the experiment was conducted to investigate the fire state of the broken objects when the freezing time during battery cooling was less than the required minimum cooling time. In the experiment, when the battery weight was 25kg, the external cooling temperature was -95°C, and the target freezing temperature was -70°C, if the value of the following formula 4 (i.e., the minimum cooling time) was 7 hours, the experiment was conducted for less than 5 hours of the minimum cooling time.

[0124] <Formula 4>

[0125] Minimum cooling time = A × (W 0.33 )

[0126] A=4×e (-0.02×dT) , W = battery weight (Kg), dT = |external cooling temperature-target temperature|, ││ represents absolute value.

[0127] Reference Figure 3c and Figure 3d The experiment tested the fire state of the broken objects when the battery was frozen for more than the minimum freezing time required for battery cooling. In the experiment, the battery weight, external cooling temperature and Figure 3a and Figure 3b Similarly, the minimum freezing time is more than 7 hours.

[0128] Table 2 below compares Figure 3a to Figure 3d The fire occurrence status of the embodiment and the comparative example based on the same battery weight, external cooling temperature and minimum freezing time. For the judgment of the fire occurrence status, if a fire is observed after the battery is crushed, it is represented as "O", and if a fire is not observed, it is represented as "X".

[0129]

Table 2

[0130]

[0131] From Table 2 above, it can be confirmed that if the battery cooling time is less than the value of Formula 4 (equivalent to the minimum cooling time), the electrolyte will not be cooled, and a fire will occur after the battery is broken. As mentioned above, if the battery is cooled with the value of Formula 4 as the minimum cooling time, the broken materials can be stably used after the battery is broken, and a fire will not occur.

[0132] <High-temperature heat treatment step - Amount of lithium compound generated based on temperature>

[0133] The high temperature heat treatment reaction generates a reduction reaction, thereby generating reaction products such as LiAlO2, Li2CO3, LiF and Li5AlO4. Specifically, the reaction products can be generated by the following reaction formulas 1 to 6.

[0134] [Reaction formula 1] Li2O(s)+Al2O3(s)=2LiAlO2(s)

[0135] [Reaction 2] 5 / 2Li2O(s)+1 / 2Al2O3(s)=Li5AlO4(s)

[0136] [Reaction 3] Li2O(s)+C(s)+O2(g)=Li2CO3(s)

[0137] [Reaction 4] Li2O(s)+2F(l)=2LiF(s)+1 / 2O2(g)

[0138] [Reaction formula 5] LiPF6(l)+H2O(l)=2HF(g)+POF3(g)+LiF(s)

[0139] [Reaction formula 6] LiAlO2(s)+2Li2CO3(s)=Li5AlO4(s)+2CO2(g)

[0140] The amount of the reaction product generated by the reaction formulas 1 to 6 will be different under the temperature and oxygen concentration range. Tables 3 to 7 below show the amount of the reaction product based on 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.

[0141]

Table 3

[0142]

[0143]

Table 4

[0144]

[0145]

[0146]

Table 5

[0147]

[0148]

Table 6

[0149]

[0150]

Table 7

[0151]

[0152] It can be confirmed from Table 3 to Table 7 above that, under the same oxygen concentration conditions, as the heat treatment temperature increases, the LiF concentration increases and then decreases sharply. Specifically, it can be confirmed that as the heat treatment temperature increases, the amount of LiF generated decreases due to partial gasification of LiF at 1300°C. More specifically, it can be confirmed that the content of LiF at 1600°C is 0. Under the same oxygen concentration conditions, if the temperature increases excessively, it is difficult to ensure the amount of LiF generated due to LiF gasification, and there is a problem of decreased lithium yield. Therefore, under the same oxygen concentration conditions, the heat treatment temperature suppresses the gasification of LiF within a range below 1500°C, thereby increasing the lithium yield. In addition, it can be confirmed from Table 3 to Table 5 above that, under the same temperature conditions, as the oxygen concentration increases, the generation of Li5AlO4 is promoted. In contrast, it can be confirmed from Tables 6 and 7 that if the oxygen partial pressure is above 1.0%, the total generation of LiAlO2-Li5AlO4 decreases as the generation of Li2CO3 becomes stable.

[0153] Figure 4 The change in the partial pressure of LiF(g) during the high temperature heat treatment step according to one embodiment of the present invention is shown.

[0154] from Figure 4 It was confirmed that the vaporization of LiF increased as the temperature increased during the high temperature heat treatment step. Specifically, it was confirmed that the recovery of lithium was not easy at a temperature of 1300° C. or higher due to the vaporization of LiF.

[0155] From Table 3 to Table 7 above and Figure 4 It is confirmed that, for the high temperature heat treatment process, when it is carried out at a temperature of 1100° C. or more, specifically at a temperature of 1300° C. or more, LiF and Li2CO3 can be minimized and Li5AlO4 and LiAlO2 can be maximized. As described above, when the temperature range in the high temperature heat treatment step is 1100 to 1500° C. and the oxygen concentration is 0.4 to 0.8% in the gas environment, the LiF gasification phenomenon is suppressed and the generation of LiAlO2 and Li5AlO4 is promoted.

[0156] Table 8 below shows the content ratio of LiAlO2 and Li5AlO4 according to the oxygen content under the conditions of the high-temperature heat treatment step at 1600°C.

[0157]

Table 8

[0158]

[0159] Figure 5 shows the content ratio of LiAlO2 and Li5AlO4 based on the oxygen content under the conditions of the high-temperature heat treatment step at 1600°C according to an embodiment of the present invention. Referring to Table 8 above and Figure 5 , it is confirmed from the content ratio that, under the same temperature conditions, as the oxygen content ratio increases, the production amount of Li5AlO4 increases. In addition, when comparing the leaching rates of the LiAlO2 and Li5AlO4 mixtures generated under the same temperature conditions in sulfuric acid, even when the content of Li5AlO4 is high, the leaching rates are at a similar level. As described above, since the leaching rates are at a similar level, conditions for mainly generating LiAlO2 or Li5AlO4 while suppressing the gasification of LiF are required.

[0160] <EH-pH diagram of Li-Al-H2O (Pourbaix diagram)>

[0161] Figure 6 shows the EH-pH diagram of Li-Al-H2O according to an embodiment of the present invention.

[0162] The EH-pH diagram is a curve graph showing the relationship between the potential and pH at which metals and metal ions in an aqueous solution exist in a thermodynamically stable manner. Figure 6 The EH-pH diagram of

[0163] is a curve graph measured at 25°C. Figure 6 It is confirmed from + that the standard electrode potential of Al is -1.66 and that of Li is -3.04, and that under strong acid conditions with a pH of 4 or less such as sulfuric acid and conditions where the potential is -0.2 V or less, Li 3+ and Al exist in ionic forms. Specifically, for the compound of Li2O and Al2O3, Li and Al ions are easily ionized under strong acids with a low pH such as sulfuric acid and present a form that easily forms a complex with SO4 2- , and the leaching rate is high regardless of the type of compound. In addition, in the high-temperature heat treatment step, as the temperature rises, a large amount of Li is lost due to the gasification of LiF(g). Therefore, in order to promote the formation of LiAlO2 and Li5AlO4, suppress the gasification of LiF, and at the same time improve the recovery rate of Li, it is preferable to perform the high-temperature heat treatment at a temperature of 1500°C or lower.

[0165] <Relationship formula of Li-Al-O compound>

[0166] Figure 7 A graph showing a relationship formula derived based on the molar ratio of Li and Al in a Li-Al-O compound according to an embodiment of the present invention is shown.

[0167] From Figure 7 It can be confirmed that after the freezing step at ultra-low temperature, when the battery is heat-treated at high temperature, the molar ratio between Li and Al of the Li-Al-O compound generated at a temperature above 900 °C satisfies the following relationship formula.

[0168] <Relationship formula>

[0169] [Al] = 0.3702 × [Li] + 0.0832 ± 0.5

[0170] [Al] and [Li] represent the number of moles of Al and Li, respectively.

[0171] It is confirmed by the above relationship formula that elements with strong oxidizing power such as Li and Al at high temperature generate stable reaction products such as LiAlO2 or Li5AlO4 at high temperature. As described above, when heat-treated at high temperature, the reaction between the Al cover or Al current collector of the LiB battery and Li in the positive electrode material occurs stably according to the above relationship formula. By satisfying the above relationship formula, there is an advantage of being able to improve the lithium recovery rate.

[0172] <Analysis of the generated lithium compound>

[0173] Analysis of the composition and crystal phase ratio of lithium compounds

[0174] It can be confirmed from Table 9 below that in the high-temperature heat-treatment step of the present invention, due to the control of temperature and oxygen concentration, the performance of the composition and crystal phase ratio is different. The crystal phase ratio is analyzed based on the quantitative XRD results and represents the proportion when the crystal phase is 100%, and can be judged in the same way as weight%.

[0175]

Table 9

[0176]

[0177] It is confirmed from Table 9 above that in the high temperature heat treatment step of the present invention, when the temperature and oxygen concentration are controlled within the range of the present invention, the generation of LiAlO2 and Li5AlO4 is promoted, the gasification of LiF is suppressed, and the actual yield of Li is improved. Specifically, it is confirmed from Experimental Examples 1 to 3 and Comparative Example 1 that if the oxygen concentration is lower than 1.0 vol%, the generation of LiAlO2 and Li5AlO4 is promoted. In addition, it is confirmed from Experimental Examples 1 to 3 and Experimental Examples 4 to 6 that the gasification of LiF is suppressed and the actual yield of Li is improved.

[0178] Analysis of the composition and crystal phase ratio of lithium compounds

[0179] Figure 8 is an XRD analysis result of a lithium compound according to an embodiment of the present invention.

[0180] Reference Figure 8 The figure shows the composition and XRD analysis results of lithium compounds generated after high-temperature heat treatment at 1300°C of the crushed product obtained by ultra-low temperature freezing and crushing without salt water discharge. It can be confirmed that the lithium compound generated after high-temperature heat treatment is composed of LiAlO2, Li2CO3 or LiF phase as a crystal phase, and the crystal phase ratio is LiAlO2 accounting for more than 12%.

[0181] Table 10 below shows the composition and XRD analysis results of lithium compounds generated when the oxygen concentration is controlled based on the temperature of 1100° C. and 1500° C. Specifically, Table 10 below shows the XRD peaks of the experimental examples and comparative examples of Table 9 above.

[0182]

Table 10

[0183]

[0184] It is confirmed from Table 10 above that in the XRD peak, the value of the intensity ratio I(A) / I(B) falls within the range of 0.1 to 1.5. The detailed description of the intensity ratio can refer to the above description. The preferred embodiments are described in detail above, but the scope of rights of the present invention is not limited to the above embodiments, and various deformations and improved forms made by those skilled in the art using the basic concepts defined in the claims also fall within the scope of rights of the present invention.

Claims

1. A composition comprising a lithium-containing compound, wherein: The lithium compound comprises LiAlO2; and at least any one of Li2CO3, LiF and Li5AlO4, Based on the total 100 weight %, the content of LiAlO2 is more than 12%.

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

3. The composition comprising a lithium-containing compound according to claim 1, wherein: In terms of weight %, the Li2CO3 is less than 30%, the LiF is less than 30% and the Li5AlO4 is less than 40%.

4. The composition comprising a lithium-containing compound according to claim 1, wherein: The total content of Li2CO3 and LiF is less than 50%.

5. The composition comprising a lithium-containing compound according to claim 1, wherein: The composition satisfies the following formula 1, <Formula 1> 3.0≤([LiAlO2]+[Li5AlO4]) / ([LiF]+[Li2CO3]))≤10.0 [LiAlO2], [Li5AlO4], [LiF] and [Li2CO3] represent the crystal phase ratios of LiAlO2, Li5AlO4, LiF and Li2CO3, respectively.

6. The composition comprising a lithium-containing compound according to claim 1, wherein: The composition satisfies the following formula 2, <Formula 2> 0.1≤I A / I B ≤1.5 I A The peak intensity value of LiAlO2 product at 2θ = 21° ± 0.5°, I B The peak intensity value of 2θ=32.6°±0.4° of the LiAlO2 product is shown.

7. The composition comprising a lithium-containing compound according to claim 1, wherein: The composition satisfies the following formula 3, <Formula 3> [Al]=0.3702×[Li]+0.0832±0.5 [Al] and [Li] represent the molar numbers of Al and Li, respectively.

8. A battery processing method, comprising: Steps to prepare the battery; The step of crushing the battery into battery fragments; and The step of subjecting the crushed battery fragments to high temperature heat treatment, The high temperature heat treatment step is carried out at a temperature ranging from 1100 to 1500° C. Furthermore, the process is performed in a gas environment with an oxygen concentration in the range of 0.4 to 0.8%.

9. The battery processing method according to claim 8, wherein: The step of preparing the battery includes the step of freezing the battery. The step of freezing the battery satisfies the following formula 4: <Formula 4> Minimum cooling time (hours) = A × (W 0.33 ) A=4×e (-0.02×dT) , W = battery weight (Kg), dT = |external cooling temperature-target temperature|, ││ represents absolute value.

10. The battery processing 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 battery processing method according to claim 8, wherein: The step of preparing the battery includes the step of performing forced discharge.

12. The battery processing method according to claim 8, wherein: After the high-temperature heat treatment step, the method further comprises a step of obtaining a composition comprising a lithium compound remaining after the nickel alloy is separated by magnetic screening.

13. The battery processing method according to claim 12, further comprising: The step of leaching the composition comprising lithium compounds with an acidic solution to recover lithium.

14. The battery processing method according to claim 13, wherein: The acidic solution satisfies a pH of 4 or less.

15. The battery processing method according to claim 13, wherein: The composition containing a lithium compound obtained by high-temperature heat treatment has a leaching rate of 95% or more in an acidic solution with a pH of 4 or less.

16. The battery processing method according to claim 8, wherein: The composition containing the lithium compound obtained by high temperature heat treatment satisfies the following formula 1, <Formula 1> 3.0≤([LiAlO2]+[Li5AlO4]) / ([LiF]+[Li2CO3]))≤10 [LiAlO2], [Li5AlO4], [LiF] and [Li2CO3] represent the crystal phase ratios of LiAlO2, Li5AlO4, LiF and Li2CO3, respectively.

17. The battery processing method according to claim 8, wherein: The lithium compound obtained by high temperature heat treatment satisfies the following formula 3, <Formula 3> [Al]=0.3702×[Li]+0.0832±0.5 [Al] and [Li] represent the molar numbers of Al and Li, respectively.

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