Patent Application
20240262703
Embodiments of the present disclosure relate generally to methods for recovering lithium precursors from waste lithium secondary batteries. More particularly, a method for recovering high-purity lithium precursors from waste lithium secondary batteries.
A secondary battery which can be charged and discharged repeatedly has been widely employed as a power source of mobile electronic devices such as camcorders, mobile phones, laptop computers, and the like, according to developments of information and display technologies. Examples of a secondary battery include a lithium secondary battery, a nickel-cadmium battery, and a nickel-hydrogen battery. The lithium secondary battery has been more actively developed and applied due to higher operational voltage and energy density per unit weight, higher charging rate, and more compact size.
The lithium secondary battery may include an electrode assembly including a cathode, an anode and a separation layer (separator), immersed in an electrolyte. The lithium secondary battery may further include an outer case having, e.g., a pouch shape for accommodating the electrode assembly and the electrolyte.
A lithium composite oxide may be used as cathode active material for the lithium secondary battery. The lithium composite oxide may further contain a transition metal such as, for example, nickel, cobalt, and manganese.
These are valuable high cost metals and as a result 20% or more of the production cost is required for manufacturing the cathode material. Additionally, environmental considerations have recently highlighted the need for developing effective recycling methods of the cathode active material.
A conventional method known as a wet method for recovering valuable metals employs leaching a waste cathode active material into a strong acid such as sulfuric acid, however, such method is disadvantageous because of poor regeneration selectivity, excessive regeneration time, and environmental pollution concerns.
Japanese Patent Publication No. 2019-178395 describes a method of recovering a lithium precursor using a wet method, however, the purity of the recovered lithium precursor is generally poor. Thus, a method for recovering high purity lithium precursor is needed.
According to an embodiment of the present disclosure, there is provided a method for recovering a lithium precursor from a used lithium secondary battery with high purity.
In a method for recovering a lithium precursor according to some embodiments of the present disclosure, a powder including lithium and valuable metals is prepared from a lithium secondary battery. The powder is reduction-treated to form a preliminary precursor mixture including a preliminary lithium precursor and valuable metal-containing particles. A primary washing of the preliminary precursor mixture with water (H2O) is performed to generate a lithium precursor aqueous solution and a precipitate. A lithium precursor is recovered by a solid-liquid separation of the lithium precursor aqueous solution from the precipitate. An additional washing and solid-liquid separation of the precipitate obtained from the solid-liquid separation is performed to recover a lithium precursor. A calcium compound is added in the primary washing or the additional washing.
In some embodiments, the reduction-treating may be performed through a fluidized bed reactor utilizing a hydrogen gas.
In some embodiments, the preliminary lithium precursor may include lithium hydroxide, lithium fluoride and lithium carbonate.
In some embodiments, lithium fluoride and lithium carbonate contained in the preliminary lithium precursor may be dissolved in water and converted into lithium hydroxide in the primary washing.
In some embodiments, the precipitate may include at least one of an unrecovered lithium compound, a valuable metal compound and the calcium compound.
In some embodiments, the primary washing may be performed through a fluidization hydration device.
In some embodiments, the primary washing may be performed at a temperature of 20 to 70° C. for 4 to 6 hours.
In some embodiments, the additional washing may be performed at a temperature of 20 to 70° C. for 0.5 to 2 hours.
In some embodiments, the powder may include a component derived from at least one of a cathode active material, an anode active material, a cathode current collector, an anode current collector, an electrolyte solution, a conductive material and a binder.
In some embodiments, the primary washing or the additional washing may include at least partially removing the component derived from the anode active material, the electrolyte solution, the conductive material or the binder by a reaction with the calcium compound.
In some embodiments, the component derived from the anode active material, the electrolyte solution, the conductive material or the binder may include a fluorine component and a carbon component.
In some embodiments, the primary washing or the additional washing may include at least partially removing the valuable metal-containing particles by a reaction with the calcium compound.
In some embodiments, the valuable metals may include aluminum.
In some embodiments, the calcium compound may include calcium oxide or calcium hydroxide.
In some embodiments, the calcium compound may be added in an amount of 2 to 10 wt % based on a total weight of the powder.
In some embodiments, the primary washing or the additional washing may be performed using 200 to 400 wt % of water based on a total weight of the powder.
In some embodiments, preparing the powder may include a dry-pulverization of the lithium secondary battery.
In some embodiments, the method of recovering the lithium precursor may include heat-treating the powder prior to the reduction-treatment.
According to some embodiments of the present disclosure, an additional washing treatment may be performed on a precipitate, so that an added calcium compound may substantially react with impurities. Accordingly, selectivity and efficiency of the lithium precursor recovery process may be further improved.
According to some embodiments of the present disclosure, an operation where water mainly reacts with a preliminary lithium precursor and an operation where the calcium compound mainly reacts with the impurities may be divided to further improve recovery efficiency of the lithium precursor.
Various embodiments of the present disclosure provide a high-purity, high-yield method for recovering a lithium precursor from a lithium secondary battery.
Hereinafter, some embodiments of the present disclosure will be described in detail with reference to
As used herein, the term “precursor” is used to comprehensively refer to a compound including a specific metal to provide the specific metal included in an electrode active material.
As used herein, the term “powder” may refer to a raw material in the form of granules or particles. The powder may be introduced into a reductive reaction treatment as will be described later.
Referring to
The lithium secondary battery may include an electrode assembly including a cathode, an anode and a separation layer interposed between the cathode and the anode. The cathode and the anode may include a cathode active material layer and an anode active material layer coated on a cathode current collector and an anode current collector, respectively.
For example, the cathode active material included in the cathode active material layer may include an oxide containing lithium and other valuable metals selected from Ni, Co, Mn, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo, Al, Ga or B.
For example, the cathode active material may include a compound represented by Chemical Formula 1 below.
In Chemical Formula 1, M1, M2 and M3 may be valuable metals selected from Ni, Co, Mn, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo, Al, Ga or B. In the chemical formula 1, the following relationships may be satisfied: 0<x≤1.1, 2≤y≤2.02, 0<a<1, 0<b<1, 0<c<1, and 0<a+b+c≤1.
In some embodiments, the cathode active material may be a nickel-cobalt-manganese (NCM)-based lithium oxide including nickel, cobalt, and manganese.
The cathode may include a cathode current collector (e.g., aluminum (Al)) and the cathode active material layer. The cathode active material layer may include a conductive material and a binder together with the cathode active material described above.
The conductive material may be included to promote an electron transfer between active material particles. For example, a carbon-based material such as graphite, carbon black, graphene, carbon nanotube, etc., or a metal-based material such as tin, tin oxide, titanium oxide, a perovskite material including LaSrCoO3 or LaSrMnO3, etc., may be included. The above conductive materials may also be used in the anode.
The binder may include, e.g., a vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, styrene butadiene rubber (SBR), polyvinyl alcohol, polyacrylic acid (PAA), carboxymethylcellulose (CMC), hydroxypropyl cellulose, diacetyl cellulose, etc. The above-described binder may also be used in the anode in addition to the cathode.
In some embodiments, the anode active material may be any suitable material known in the art being capable of intercalating and de-intercalating lithium ions without a particular limitation. For example, a carbon-based material such as crystalline carbon, amorphous carbon, a carbon composite a carbon fiber, etc.; a lithium alloy; silicon (Si)-based compounds or tin may be used.
As described above, the anode may include an anode current collector (e.g., copper (Cu)) and the anode active material layer, and the anode active material layer may include a conductive material and a binder together with the anode active material.
In some embodiments, the electrolyte solution may include a non-aqueous electrolyte solution. The non-aqueous electrolyte solution may include a lithium salt as an electrolyte and an organic solvent. The lithium salt may be represented by, e.g., Li+X−. An anion (X−) of the lithium salt may F−, Cl−, Br−, I−, NO3−, N(CN)2−, BF4−, ClO4−, PF6−, (CF3)2PF4−, (CF3)3PF3−, (CF3)4PF2−, (CF3)5PF−, (CF3)6P−, CF3SO3−, CF3CF2SO3−, (CF3SO2)2N−, (FSO2)2N−, CF3CF2(CF3)2CO−, (CF3SO2)2CH−, (SFs)3C−, (CF3SO2)3C−, CF3(CF2)7SO3−, CF3CO2−, CH3CO2−, SCN− and (CF3CF2SO2)2N−, etc.
In some embodiments, the preparation of the powder may include separating a waste battery into a cell unit. For example, a case and an electric wiring of the waste battery may be separated so that the waste battery may be separated to a module unit, and the module unit may be further separated into the cell unit.
In some embodiments, the preparation of the powder may include separating the cathode from a battery cell, and may include separating the cathode active material layer from the cathode.
In some embodiments, the preparation of the powder may include dry pulverization of the lithium secondary battery. Accordingly, the form of the powder may be prepared.
In some embodiments, the dry-pulverized lithium secondary battery may be the cell unit, a cathode unit or a cathode active material layer unit as described above.
In some embodiments, the powder may include components derived from at least one of the cathode active material, the anode active material, the cathode current collector, the anode current collector, the electrolyte solution, the conductive material and the binder.
In some embodiments, the powder may be heat-treated before being introduced into a reductive reactor as will be described later. Impurities such as the conductive material and the binder may be removed or reduced by the heat treatment so that a lithium-valuable metal oxide of the powder may be introduced into the reductive reactor with high purity. A temperature of the heat treatment may be in a range from, e.g., about 100 to 500° C., or from about 350 to 450° C. Within the above range, the impurities may be substantially removed, so that decomposition and damages of the lithium-valuable metal oxide may be prevented.
In some embodiments, an average particle diameter (an average particle diameter in a volume accumulation distribution) (D50) of the powder may be in a range from 5 to 100 μm. Within the above range, a reductive reaction through a fluidized bed reactor as described later may be easily performed.
In some embodiments, the powder may be reduced to prepare a preliminary precursor mixture including a preliminary lithium precursor and valuable metal-containing particles, e.g., in operation S20.
The valuable metal-containing particles may include Ni, Co, Al, NiO, CoO, MnO, Al2O3, etc.
In some embodiments, the preliminary lithium precursor may include lithium hydroxide (LiOH) or lithium oxide (Li2O), and may include lithium fluoride (LiF) or lithium carbonate (LizCO3) derived from the anode active material, the electrolyte solution, the conductive material or the binder.
In some embodiments, the powder may be introduced into the reductive reactor, and may be reduced using a hydrogen gas.
During the reduction treatment, the hydrogen gas may be injected into a lower portion of the reductive reactor. The hydrogen gas may contact the powder while being supplied from the lower portion of the reductive reactor. Thus, the injected powder may be converted into the preliminary precursor mixture by reacting with the reducing reactive gas while moving to an upper portion of the reactor or residing in a reactor body.
In some embodiments, the hydrogen gas may be injected or a carrier gas may be injected together to form a fluidized bed in the reductive reactor. Accordingly, the reductive reactor may serve as a fluidized bed reactor. The carrier gas may include, e.g., an inert gas such as nitrogen (N2), argon (Ar), and the like.
As the powder may repeatedly rise, reside and fall when being treated in the fluidized bed, a reaction contact time may be increased and dispersion of particles may be improved. Thus, the preliminary precursor mixture having a uniform size may be obtained.
However, the embodiments of the present disclosure are not necessarily limited to the fluidized bed reaction. For example, a fixed reaction where a cathode active material mixture may be pre-loaded into a batch reactor or a tubular reactor, and then the reducing reactive gas is supplied may be performed.
In some embodiments, a temperature of the reduction treatment may be adjusted in a range from about 400 to 800° C., or from about 400 to 600° C., or from about 400 to 500° C. Further, the reduction treatment may be finely controlled through process conditions such as the hydrogen concentration, the reaction temperature, and the reduction reaction time.
In some embodiments, the prepared preliminary precursor mixture may be primary-washed with water (H2O) to generate an aqueous lithium precursor solution and a precipitate, e.g. in operation S30.
In some embodiments, an inert gas may be injected during the primary washing to form a fluidized bed in a washing treatment apparatus. That is, the primary washing may be performed by a fluidized hydration apparatus. The type of the inert gas is not limited, and may include, e.g., nitrogen (N2) or argon (Ar).
During the washing treatment in the fluidized hydration apparatus, a contact area and a contact time may be increased as the preliminary lithium precursor mixture may repeatedly rise and fall in the aqueous solution. Accordingly, a reaction between the water and the preliminary lithium precursor as described later may be performed more easily.
The preliminary precursor mixture may be uniformly dispersed without being aggregated by mixing the inert gas. Accordingly, the preliminary lithium precursor may be prevented from being aggregated and precipitated with the valuable metal-containing particles, thereby increasing a recovery ratio of a lithium precursor.
Lithium hydroxide may be advantageous as the lithium precursor from aspects of charging/discharging properties, life-span properties, high-temperature stability, etc., of the lithium secondary battery. For example, lithium carbonate may cause a deposition reaction on the separation layer, thereby degrading life-span stability.
Additionally, lithium hydroxide may be advantageous as the lithium precursor from aspects of lithium precursor regeneration and process efficiency. For example, a solubility of lithium hydroxide in water may be greater than that of lithium carbonate or lithium fluoride, and thus an amount of water required for the washing treatment may become small. Accordingly, device size and process time may be reduced.
In some embodiments, lithium fluoride and lithium carbonate contained in the preliminary lithium precursor may be dissolved in water and converted into lithium hydroxide by the primary washing. Therefore, a high-purity lithium precursor converted to the form of lithium hydroxide form may be obtained.
In some embodiments of the present disclosure, a calcium compound may be added in the primary washing.
In some embodiments, the calcium compound may include calcium oxide or calcium hydroxide. The primary washing may include at least partially removing components derived from the anode active material, the electrolyte solution, the conductive material or the binder by a reaction with the calcium compound.
In some embodiments, the components derived from the anode active material, the electrolyte solution, the conductive material or the binder may include a fluorine component or a carbon component. When the fluorine component and the carbon component react with lithium, lithium fluoride (LiF) and lithium carbonate (LizCO3) are formed. Accordingly, the recovery ratio of lithium precursor may be decreased. The calcium compound added in the primary washing may react with the fluorine component and the carbon component contained in the preliminary precursor mixture to form calcium fluoride (CaF2) and calcium carbonate (CaCO3), and may be precipitated.
In some embodiments, the calcium compound added in the primary washing may be precipitated. A dissolution rate of the lithium precursor in water is greater than that of the calcium compound. Thus, when the calcium compound is added in the primary washing, a pH of the lithium precursor aqueous solution may be increased as the lithium precursor dissolves more quickly in water. Therefore, the calcium compound that is not dissolved in the lithium precursor aqueous solution or the precipitated calcium compounds after being dissolved may be sedimented.
As the calcium compound is precipitated, a precipitation reaction with the carbon component and the fluorine component of the calcium compound added in the primary washing may not easily occur. Further, the precipitation reaction with the carbon and fluorine components of the calcium compound may substantially occur in an additional washing as described later. A phase where the calcium compound mainly reacts with the components derived from the anode active material, the electrolyte solution, the conductive material or the binder may be the additional washing operation as described later. In consideration of the above aspects, the calcium compound may be selectively added to the primary washing operation or the additional washing as described later.
In some embodiments, the valuable metal-containing particles included in the preliminary precursor mixture may not be dissolved in or react with water in the primary washing, and may be precipitated.
In some embodiments, the valuable metal-containing particles may react with the calcium compound added in the primary washing to be precipitated, and may be removed by a solid-liquid separation, which will be described later.
In some embodiments, the valuable metal that reacts with the calcium compound to be precipitated may include aluminum. For example, an aluminum compound contained in the valuable metal-containing particles may be precipitated after reacting with the calcium compound, and may be removed by the solid-liquid separation, as described later. When the calcium compound is added in the primary washing, the aluminum compound may be more easily precipitated as the pH increases. The precipitation of the aluminum compound may substantially occur in the primary washing.
In some embodiments, as the amount of the added calcium compound increases, an amount of the aluminum compounds precipitated and removed may increase.
In some embodiments, the preliminary lithium precursor that is not dissolved in water may be precipitated during the primary washing. For example, the preliminary lithium precursor may be aggregated with the valuable metal-containing particles, and precipitated. Additionally, a lithium compound having a low solubility in water of the preliminary lithium precursor may be precipitated in a solid phase.
In some embodiments, the precipitate may include at least one of an unrecovered lithium compound, a valuable metal compound and a calcium compound.
In some embodiments, the calcium compound may be added in the primary washing in an amount of 2 to 10 wt % based on a total weight of the powder. When adding 2 wt % of the calcium compound based on the total weight of the powder, 70% or more of the components derived from the binder and the conductive material may be removed. When adding 5 wt % or more of the calcium compound based on the total weight of the powder, 90% or more of the fluorine component and the carbon component may be removed.
In some embodiments, the primary washing may be performed using 200 to 400 wt % of water based on the total weight of the powder. If 200 wt % or more of water is added, the preliminary precursor mixture and the calcium compound may be uniformly mixed so that a selectivity of lithium hydroxide may be improved. The added amount of water is not limited to the above range, and may be adjusted according to a viscosity of the preliminary precursor mixture and a standard of the reactor.
In some embodiments, the primary washing may be performed at a temperature in a range from 20 to 70° C. for 4 to 6 hours. When performing at a temperature of 70° C. for 4 hours or more, 90% or more of the binder and conductive material-derived components may be removed, and a hydration temperature and time may be adjusted depending on an operating situation.
In some embodiments, the lithium precursor aqueous solution may be solid-liquid separated from the precipitate to recover the lithium precursor (e.g., in an operation S40). The calcium compounds or the valuable metal compounds precipitated in the solid phase may be separated by the solid-liquid separation, and the high-purity lithium precursor may be obtained.
In some embodiments, the solid-liquid separation may be performed using a centrifuge.
In some embodiments, the lithium precursor aqueous solution may include lithium hydroxide, lithium carbonate and lithium fluoride, and may be substantially separated into a lithium hydroxide aqueous solution to obtain the high-purity lithium precursor in the form of lithium hydroxide.
In some embodiments, the lithium precursor may be recovered by additional washing and solid-liquid separation of the precipitate obtained through the solid-liquid separation, e.g., in operation S50).
A first precipitate generated through the primary washing and solid-liquid separation (e.g., in operations S30 and S40) may be additionally washed with water (e.g., in operation S50) to produce a second lithium precursor aqueous solution and a second precipitate.
The preliminary lithium precursor contained in the first precipitate may be dissolved in the additional washing and may be recovered as the second lithium precursor aqueous solution.
For example, the preliminary lithium precursor aggregated and precipitated with the valuable metal-containing particles during the primary washing (e.g., the operation S30) may be dissolved in the additional washing (e.g., the operation S50). Lithium fluoride and lithium carbonate contained in the preliminary lithium precursor may be converted to lithium hydroxide in the additional washing or removed by the washing. Thus, the high-purity lithium precursor converted into lithium hydroxide form may be produced.
In some embodiments, when the calcium compound is added in the primary washing (e.g., the operation S30), the calcium compound that may not be dissolved in the primary washing to be included in the first precipitate may be dissolved substantially by the additional washing (e.g., the operation of S50) and may be reacted with components derived from the anode active material, the electrolyte solution, the conductive material or the binder to be at least partially removed.
In some embodiments, the components derived from the anode active material, the electrolyte solution, the conductive material or the binder may include a fluorine component and a carbon component. The calcium compound dissolved in the additional washing may react with the fluorine component and the carbon component to form calcium fluoride (CaF2) and calcium carbonate (CaCO3) and may be precipitated.
In some embodiments, during the additional washing, the calcium compound that may be added in the primary washing and may not be dissolved in water may be precipitated. The valuable metal-containing particles included in the preliminary precursor mixture may be precipitated without being dissolved or reacted in water by the additional washing. During the additional washing, the preliminary lithium precursor that is not dissolved in water may be precipitated.
In some embodiments, the second lithium precursor aqueous solution and the second precipitate may be separated by the additional solid-liquid separation. The second precipitate may include unrecovered lithium compound, the calcium compound the and valuable metal compounds.
In some embodiments, the calcium compound may be added in the primary washing or the additional washing.
For example, the calcium compound may not be added in the primary washing, but may be added in the additional washing. As described above, if the calcium compound is added in the primary washing, the lithium precursor may be dissolved, and the calcium compound may not react with the fluorine and carbon components and may be precipitated. Thus, the effect of the embodiments of the present disclosure may be implemented even if the calcium compound is not added in the primary washing and is added in the additional washing. In this case, the above-mentioned valuable metal removal effect may occur in the additional washing.
In some embodiments, the additional washing and the solid-liquid separation (e.g., operation S50) may be repeated in a plurality of cycles.
Substantially all lithium in the powder may be recovered by the additional washing and the solid-liquid separation.
If the calcium compound is added in the primary washing, the calcium compound that may not be dissolved in the primary washing and may be precipitated among the added calcium compound may be dissolved in the additional washing. In the additional washing, the calcium compound may react with impurities to remove the fluorine and carbon components, and substantially all lithium in the powder may be recovered in the form of lithium hydroxide.
In some embodiments, the additional washing may be performed with 200 to 400 wt % of water based on the total weight of the powder. The additional washing may be performed for 0.5 to 2 hours at a temperature of 20 to 70° C.
The added amount of water, and the temperature and time of the treatment are not limited to the above-mentioned range, and may be adjusted depending on the number of cycles of the additional washing, a viscosity of the preliminary precursor mixture, operating conditions, etc. For example, when the additional washing is performed only once after the primary washing, 8000 wt % of water based on the total weight of the powder may be added to achieve a desired recovery ratio, and may be performed at a temperature of 70° C. for 20 hours.
According to embodiments of the present disclosure, a method for recovering lithium hydroxide as the lithium precursor with a high selectivity may be provided.
In some embodiments, impurities derived from the binder and the conductive material may be removed by performing the heat treatment before the reduction treatment. Thus, contents of lithium carbonate and lithium fluoride among the lithium compounds contained in the lithium precursor aqueous solution may be reduced.
In some embodiments, the reduction process may utilize the hydrogen gas and a carbon-containing gas may be excluded. Accordingly, when washing the preliminary precursor mixture obtained through the reduction treatment, a content of lithium hydroxide in the lithium precursor aqueous solution may be increased, and by-products of other types of the lithium precursor such as lithium carbonate may be prevented.
The by-products of other types of the lithium precursor such as lithium carbonate and lithium fluoride may be prevented, so that an added amount of the calcium compound may be reduced.
In some embodiments, the lithium precursor may be collected through a dry reductive reaction that may exclude the use of a solution. Therefore, an amount of by-products may be lowered, yield may be increased, and wastewater treatment may not be required, so that an eco-friendly process may be implemented.
Hereinafter, specific experimental examples for enhancing the understanding of the embodiments of the present disclosure are presented, but this is merely illustrative of the embodiments and does not limit the accompanying claims. It is apparent to those skilled in the art that various modifications and modifications to the embodiments are possible within the scope and technical concepts of the present disclosure. Such alterations and modifications are duly included in the appended claims.
A cell separated from a waste lithium secondary battery was discharged, and then cut into several cm-sized pieces and pulverized by a milling. The pulverized cell was heat-treated at 450° C. for 1 hour to collect 200 g of powder containing a Li—Ni—Co—Mn oxide.
The collected powder was loaded into a fluidized bed reactor, and a mixed gas of 20 vol % hydrogen/80 vol % nitrogen was injected from a bottom of the reactor at a flow rate of 5.5 L/min for 4 hours to proceed with a reductive reaction. A temperature in the fluidized bed reactor was maintained at 460° C. After performing the reductive reaction, a temperature of the reactor was lowered to 25° C. to obtain a preliminary precursor mixture.
300 wt % of water based on a total weight of the powder, 10 wt % of calcium oxide (CaO) based on the total weight of the powder and the obtained preliminary precursor mixture were introduced into a fluidizing hydration device. A flow was formed by injecting 100 vol % nitrogen gas at 30° C. at a flow rate of 12 L/min for 5 hours, and a solid-liquid separation was performed through a centrifuge to obtain a first lithium precursor aqueous solution and a first precipitate (a first washing and solid-liquid separation).
The first precipitate was put in a hydration device together with 300 wt % of water based on the total weight of the powder, stirred at 45° C. for 1 hour, and a solid-liquid separation was performed through a centrifuge to obtain a second lithium precursor aqueous solution and a second precipitate (a second washing with water and solid-liquid separation).
The second precipitate was put in a hydration device together with 200 wt % of water based on the total weight of the powder, stirred at 45° C. for 1 hour, and a solid-liquid separation was performed through a centrifuge to obtain a third lithium precursor aqueous solution and a third precipitate (a third washing and solid-liquid separation).
The third precipitate was put in a hydration device with 200 wt % of water based on the total weight of the powder, stirred at 45° C. for 1 hour, and a solid-liquid separation was performed through a centrifuge to obtain a fourth lithium precursor aqueous solution and a fourth precipitate (a fourth washing and solid-liquid separation).
Concentrations of lithium hydroxide, lithium carbonate and lithium fluoride remaining in each of the first to fourth lithium precursor aqueous solutions were measured, and a weight ratio (recovery ratio) of each lithium compound contained in each of the first to fourth lithium precursor aqueous solutions was measured with respect to the total weight of the lithium compound recovered in the aqueous solution. The measured results are shown in Table 1 below.
A cell separated from a waste lithium secondary battery was discharged, and then cut into several cm-sized pieces and pulverized by a milling. The pulverized cell was heat-treated at 450° C. for 1 hour to collect 200 g of powder containing a Li—Ni—Co—Mn oxide.
The collected powder was loaded into a fluidized bed reactor, and a mixed gas of 20 vol % hydrogen/80 vol % nitrogen was injected from a bottom of the reactor at a flow rate of 5.5 L/min for 4 hours to proceed with a reductive reaction. A temperature in the fluidized bed reactor was maintained at 460° C. After performing the reductive reaction, a temperature of the reactor was lowered to 25° C. to obtain a preliminary precursor mixture.
300 wt % of water based on a total weight of the powder, 1.75 wt % of calcium oxide (CaO) based on the total weight of the powder and the obtained preliminary precursor mixture were introduced into a fluidizing hydration device. A flow was formed by injecting 100 vol % nitrogen gas at 30° C. at a flow rate of 12 L/min for 5 hours, and a solid-liquid separation was performed through a centrifuge to obtain a first lithium precursor aqueous solution and a first precipitate (a first washing and solid-liquid separation).
The first precipitate was put in a hydration device together with 8000 wt % of water based on the total weight of the powder, stirred at 70° C. for 20 hours, and a solid-liquid separation was performed through a centrifuge to obtain a second lithium precursor aqueous solution and a second precipitate (a second washing with water and solid-liquid separation).
Concentrations of lithium hydroxide, lithium carbonate, lithium fluoride and aluminum remaining in the final lithium precursor aqueous solutions including the first and second lithium precursor aqueous solutions obtained by the solid-liquid separation were measured, and weight ratios of each lithium compound and aluminum with respect to the total weight of the lithium compound recovered in the aqueous solution. The measured results are shown in Table 3 below.
The same process as that in Example 2 was performed except that 3.5 wt % of calcium oxide (CaO) was added based on the total weight of the powder. The measured results are also shown in Table 3 below.
The same process as that in Example 2 was performed except that 5.25 wt % of calcium oxide (CaO) was added based on the total weight of the powder. The measured results are also shown in Table 3 below.
The same process as in Example 2 was performed except that 7% by weight of calcium oxide (CaO) was added based on the total weight of the powder. The measurement results are also shown in Table 3 below.
The same process as in that Example 1 was performed except that calcium oxide was not included. The measured results are shown in Table 2 below.
The same process as in that Example 2 was performed except that calcium oxide was not included. The measured results are also shown in Table 3 below.
Referring to Tables 1 and 2, when the calcium compound was included within the range according to the above-described embodiments of the present disclosure, it was confirmed that a ratio of lithium hydroxide in the lithium compound recovered in the aqueous solution increased and ratios of lithium carbonate and lithium fluoride decreased. When the washing treatment was performed only once, the ratio of lithium hydroxide in Comparative Example 1 was higher than that of Example 1. However, when the washing treatment was performed two or more times, it was confirmed that the ratio of lithium hydroxide in Example 1 was higher than that of Comparative Example 1.
Referring to Table 3, when the calcium compound was included within the range of the above-described embodiments of the present disclosure, it was confirmed that the ratio of lithium hydroxide in the lithium compound recovered in the aqueous solution increased and the ratios of lithium carbonate and lithium fluoride decreased. It was confirmed that the amount of aluminum contained in the aqueous solution decreased as the input amount of the calcium compound increased.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2021-0135782 | Oct 2021 | KR | national |
This application is a Bypass Continuation Application of PCT/KR2022/015266 filed on Oct. 11, 2022, which claims priority to Korean Patent Application No. 10-2021-0135782 filed on Oct. 13, 2021. The entire disclosure of each of the foregoing applications is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/KR2022/015266 | Oct 2022 | WO |
| Child | 18632296 | US |
