Method for recycling lithium metal in waste lithium battery cathode material

Abstract

The application discloses a method for recycling metal lithium in a positive material of a waste lithium battery. First, the positive material of a lithium ion battery to be recycled is dissolved in a nitric acid solution to prepare a to-be-recycled stock solution; the to-be-recycled stock solution is injected into a filler chromatographic column, the filler is polyacrylonitrile fiber modified by diethylenetriamine amination, and effluent within six column volumes is collected; the filler chromatographic column is replaced to continue the above process until all the to-be-recycled samples are processed, and the recycling of metal lithium in the waste lithium battery material is completed. The application maximally improves the Li recycling rate.

Description

Technical Field

[0001] This invention belongs to the field of valuable metal recycling technology of waste batteries, and relates to a method for recycling metallic lithium in the positive electrode material of waste lithium batteries. Background Technology

[0002] Lithium-ion batteries offer numerous advantages, including high operating voltage, high energy density, wide operating temperature range, and long cycle life. The main cathode materials for lithium-ion batteries include lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide (LCM), and lithium nickel cobalt aluminum oxide (LCA). Due to the rapid development of industries such as portable electronic devices, new energy electric vehicles, and large-scale energy storage, the production and use of lithium-ion batteries are increasing rapidly, leading to a surge in demand for metal elements such as Co, Ni, Mn, and Li. Consequently, the number of retired and discarded lithium-ion batteries is also increasing rapidly. If these discarded batteries are not properly disposed of, it will result in serious resource waste. Compared to directly extracting these metal elements from raw materials, recycling lithium-ion batteries will alleviate resource pressure and reduce energy consumption and costs. Furthermore, the metal elements in discarded lithium-ion batteries may also pollute soil and water sources. Therefore, the recycling of discarded lithium-ion batteries has significant economic and environmental value.

[0003] Currently, the main methods for recovering metal elements from waste lithium-ion battery cathode materials include pyrometallurgy and hydrometallurgy. Pyrometallurgy directly extracts metals or metal oxides from the electrodes using high-temperature treatment. While simple, pyrometallurgical processes result in low purity recovered materials, high energy consumption, and the electrolyte and binders in the battery produce harmful gases such as CO, CO2, and VOCs due to high-temperature reactions, requiring secondary waste gas treatment facilities. Furthermore, the high-temperature smelting process in direct pyrometallurgy leads to lithium loss. Hydrometallurgy involves disassembling the battery casing, crushing and screening it to obtain the electrode materials. Valuable metals in the electrode materials are leached in acid or biological solutions, followed by separation to obtain the corresponding salts or oxides of each metal. The hydrometallurgical process mainly includes cathode pretreatment, valuable metal leaching, and valuable metal separation and recovery. Although hydrometallurgy can recover almost all metals from waste NCM batteries, the use of inorganic acids and alkalis as leaching agents causes many environmental problems, while organic acids, although environmentally friendly, are relatively expensive. Furthermore, due to the high valence state of the active cathode material and the strong binding of organic binders in waste lithium batteries, some hydrometallurgical processes suffer from relatively long leaching times and low efficiency. During the leaching process, impurities such as aluminum and iron enter the acid solution along with lithium, nickel, cobalt, and manganese, making the process of separating valuable metals from the leachate lengthy and cumbersome. Most importantly, lithium is also dispersed in these separation and refining stages, resulting in low lithium recovery rates.

[0004] In recent years, adsorption chromatography has attracted widespread attention and research in the field of chromatographic separation. Its working principle utilizes the difference in partition coefficients between different components in the stationary phase adsorbent and the mobile phase, resulting in varying retention capacities of different components in the adsorbent, thus achieving efficient separation of substances. This method can effectively achieve the separation and purification of multiple components. When the solid and liquid phases move relative to each other, the different adsorption degrees of the stationary phase on each component in the solution cause multiple partitioning processes during the flow. Even with slight differences in partition coefficients, a good partitioning effect can be achieved, thus realizing efficient separation of multiple components. Chinese patent application CN116262946A discloses a method for separating and extracting valuable metals from acidic leaching solutions of ternary materials from waste batteries using a chromatographic separation system. However, this method uses a series countercurrent chromatography system and a bipolar membrane electrodialysis system, separating and recovering four metal ions through a multi-stage separation system, making the separation process relatively cumbersome. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for recovering metallic lithium from waste lithium battery cathode materials, thereby solving the technical problem of low lithium recovery efficiency in the prior art.

[0006] This invention is achieved through the following technical solution:

[0007] A method for recovering metallic lithium from waste lithium battery cathode materials includes the following steps:

[0008] S1: Dissolve the positive electrode material of the lithium-ion battery to be recycled in nitric acid solution to obtain the raw solution to be recycled;

[0009] S2: Inject the original solution to be recovered into a packed column, wherein the packed column is adiethylenetriamine-aminated modified polyacrylonitrile fiber, and collect the eluent up to six column volumes.

[0010] S3: Replace the packing column and repeat step S2 until all samples to be recovered are processed, thus completing the recovery of metallic lithium from the waste lithium battery materials.

[0011] Preferably, the column volume of the packed column is 10-20 cm³. 3 .

[0012] Preferably, the packing density of the chromatographic column is 8-15 cm³. 3 .

[0013] Preferably, the pH of the original solution to be recovered is adjusted to 2-6 before it is injected into the packed column.

[0014] Preferably, before injecting the original solution to be recovered into the packed column, the concentration of the original solution to be recovered is adjusted to 0.1~20 mmol / L.

[0015] Preferably, the flow rate of the original solution to be recovered in the packed column is 0.05~0.60 mL / min.

[0016] Preferably, in step S2, the effluent within the first three column volumes is collected.

[0017] Preferably, in step S3, the packed column is replaced with a packed column that has not undergone adsorption treatment or a packed column that has been eluted with an elution buffer.

[0018] Preferably, the eluent is nitric acid with a concentration of 0.01~0.2 mol / L.

[0019] Preferably, the eluent used during elution is 10 to 12 column volumes.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] This invention discloses a method for recovering metallic lithium from the cathode material of spent lithium batteries. The method first dissolves the cathode material in nitric acid solution to ensure effective release of metallic lithium. Then, amination-modified polyacrylonitrile fibers are used as fillers. Through amination modification with diethylenetriamine, amino functional groups are introduced into the polyacrylonitrile fibers. The modified fibers exhibit selective adsorption of metal ions, and these amino functional groups have a strong complexing ability for transition metal ions, effectively realizing the recovery of lithium ions from the mixed metal solution. The amino-modified polyacrylonitrile fibers generate OH- in water. - Li ions can exchange with various anions to adsorb them, and can also form coordinate bonds with metal ions using N as the coordinating atom, achieving effective adsorption of metal cations. This invention employs a single-stage chromatographic separation system to separate Li from a mixed solution, achieving a Li recovery rate exceeding 99%. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the separation device in this invention;

[0024] Figure 2 This is a schematic diagram illustrating the principle of separating metal ions using ammoniated fibers in this invention.

[0025] Figure 3 The adsorption curve (a) and elution curve (b) of metal ions in the cathode material of a ternary lithium-ion battery in Example 1 of this invention are shown.

[0026] Figure 4 The adsorption curve (a) and elution curve (b) of metal ions in the Co-Li system in Example 2 of this invention are shown.

[0027] Figure 5 The adsorption curve (a) and elution curve (b) of metal ions in the Mn-Li system in Example 3 of this invention are shown.

[0028] Figure 6 This is a graph showing the effect of different mixed solution acidity values ​​on fiber adsorption of mixed metal ions in this invention;

[0029] Figure 7 This is a graph showing the separation effect of metal ions at an injection concentration of 10 mmol / L in this invention.

[0030] Figure 8 In this invention, the fiber-filled adsorption column is filled to its full length, and the fiber is effective against Li. + Ni 2+ Co 2+ Mn 2+ Adsorption curve;

[0031] Figure 9 In this invention, when the peristaltic pump power is 2.0 rpm, the fiber is related to Li... + Ni 2+ Co 2+ Mn 2+ Adsorption curve;

[0032] Figure 10 When the elution acid concentration is 0.2 mol / L, Li + Ni 2+ Co 2+ Mn 2+ The elution curve;

[0033] Figure 11 To analyze the adsorption of (a)Li on the fiber in Example 1 + (b)Ni 2+ (c)Co 2+ (d)Mn 2+ XPS plot;

[0034] Figure 12 To investigate the (e)Li on the fibers after elution in Example 1 + (f)Ni 2+ (g)Co2+ (h)Mn 2+ XPS plot;

[0035] Figure 13 The images shown are electron microscope (EM) images of the fibers before metal adsorption (a), the fibers after metal adsorption (b), and the fibers after elution (c) in Example 1.

[0036] The components include: 1. beaker, 2. peristaltic pump, 3. injection tubing, 4. fiber adsorption column, and 5. automatic collector. Detailed Implementation

[0037] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0038] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0039] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0040] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0041] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0042] This invention provides a method for recovering metallic lithium from the cathode material of spent lithium batteries, comprising the following steps:

[0043] S1: Dissolve the positive electrode material of the lithium-ion battery to be recycled in nitric acid solution to obtain the raw solution to be recycled;

[0044] The lithium-ion batteries include ternary lithium-ion batteries, lithium cobalt oxide batteries, or lithium manganese oxide batteries; the concentration of the nitric acid solution here is 0.2 mol / L.

[0045] S2: Inject the original solution to be recovered into a packed column, wherein the packed column is adiethylenetriamine-aminated modified polyacrylonitrile fiber, and collect the eluent up to six column volumes.

[0046] The column volume of the packed column is 10-20 cm³. 3 The packing volume of the chromatographic column is 8-15 cm³. 3 .

[0047] Preferably, the pH of the original solution to be recovered is adjusted to 2-6 before it is injected into the packed column.

[0048] Before injecting the original solution to be recovered into the packed column, adjust the concentration of the original solution to be recovered to 0.1~20 mmol / L.

[0049] The flow rate of the original solution to be recovered in the packed column is 0.05~0.60 mL / min.

[0050] In a more preferred embodiment, the effluent within the first three column volumes is collected.

[0051] The preparation process of diethylenetriamine amination-modified polyacrylonitrile fiber in this invention is as follows:

[0052] A certain volume of diethylenetriamine was added to a high-pressure reactor, and a certain mass of polyacrylonitrile fiber was placed in the system and stirred evenly to achieve a diethylenetriamine to polyacrylonitrile fiber ratio of 5 mL:1 g. Then, sodium carbonate solution was added, and the mixture was stirred evenly. The reaction system was allowed to react at 115 °C for 5 h to obtain the diethylenetriamine-modified polyacrylonitrile fiber. The ratio of polyacrylonitrile fiber to sodium carbonate solution was 1 g:1 mL, and the concentration of sodium carbonate solution was 0.01 g / mL.

[0053] S3: Replace the packing column and repeat step S2 until all samples to be recovered are processed, thus completing the recovery of metallic lithium from the waste lithium battery materials.

[0054] Replace the packed column with a packed column that has not undergone adsorption treatment or a packed column that has been eluted with elution solution.

[0055] The eluent is nitric acid with a concentration of 0.01~0.2 mol / L.

[0056] During elution, the eluent used is 10 to 12 column volumes.

[0057] This study used ammoniated fibers as an adsorption carrier and employed a constructed separation device to separate waste NCM battery cathode material Li using adsorption chromatography. + Recycling. For example... Figure 1 As shown, the separation device consists of a beaker 1, a peristaltic pump 2, a sample inlet tube 3, a fiber adsorption column 4, and an automatic collector 5. The original solution to be recovered is pumped into the fiber adsorption column 4 by the peristaltic pump 2. During the adsorption process, due to the difference in the partition coefficient between the adsorption fiber and the metal ions in the mixed solution, the retention capacity of each metal ion in the adsorbent is different, thus causing the metal ions to be distributed multiple times during the flow process, thereby achieving efficient separation between metal ions.

[0058] like Figure 2 As shown, this invention employs chromatographic separation technology, using diethylenetriamine-aminated polyacrylonitrile fiber as the adsorption carrier, to separate and recover valuable metals Li, Ni, Co, and Mn from waste ternary lithium-ion battery cathode materials, and to separate and recover Co and Li from binary lithium cobalt oxide cathode materials, and Mn and Li from lithium manganese oxide cathode materials. In the multi-component column adsorption-elution process, under optimal adsorption and elution conditions, the recovery rates of Li, Ni, Co, and Mn were 99.4%, 80.2%, 89.8%, and 71.4%, respectively. The purities of Ni, Co, and Mn in the 5th batch volume (BV) effluent were 65.5%, 22%, and 12.5%, respectively. In the binary lithium cobalt oxide system, under optimal adsorption and elution conditions, the recovery rate of Li was 96.1%, and the recovery rate of Co was 99.6%. In the binary lithium manganese oxide system, under optimal adsorption and elution conditions, the recovery rate of Li was 96.4%, and the recovery rate of Mn was 99.3%.

[0059] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0060] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0061] Example 1

[0062] This example uses column adsorption separation technology to separate four metals (Li, Ni, Co, and Mn) from a mixture of ternary lithium-ion battery cathode materials. 10.0 g of amination-modified polyacrylonitrile fiber was accurately weighed using an electronic balance and soaked in deionized water at 25 °C for 12 h to ensure complete wetting. The soaked fiber was then packed into an adsorption column, filling the entire column. During packing, the fiber was continuously compressed using a glass rod to minimize gaps between fibers. The concentration of the ternary mixture was 10 mmol / L, and the peristaltic pump was adjusted to 1.0 rpm (injection flow rate of 0.29 mL / min). After the reaction, 0.2 mL of the solution was taken using a 0.2 mL pipette and placed in a 10 mL centrifuge tube for 50-fold dilution. After adsorption, the entire injection solution in the adsorption column and inlet / outlet tubing was drained. The injection solution was then replaced with 0.2 mol / L nitric acid to elute the metals adsorbed on the fiber. After the reaction was complete, 0.2 mL of the solution was transferred to a 10 mL centrifuge tube using a 0.2 mL pipette and diluted 50 times. The concentration of metal ions in the solution was determined using ICP-OES.

[0063] The results showed that under the optimal adsorption-elution conditions—a mixed solution pH of 2, an injection solution concentration of 10 mmol / L, adsorption fiber packed to full column, a peristaltic pump power of 1.0 rpm, and an eluent nitric acid concentration of 0.2 mol / L—the separation of the four metal ions was relatively good. Figure 3 As shown in Figure (a), during the adsorption process, Li separates from Ni, Co, and Mn at 2 BV, with a separation interval of 5 BV, and the recovery rate of Li is 99.4%. Ni, Co, and Mn also begin to separate at 12 BV, and the entire adsorption process reaches adsorption equilibrium at 32 BV. Therefore, Li can be separated from Ni, Co, and Mn through adsorption. Furthermore, as... Figure 3 As shown in Figure (b), during the elution process, Ni exhibited ideal separation at 1 BV, while Co and Mn showed ideal separation at 5 BV, and were completely eluted from the fibers in a relatively small column volume of 10 BV. In the first 5 BV, the recovery rates of Ni, Co, and Mn were 80.2%, 89.8%, and 71.4%, respectively. The purities of Ni, Co, and Mn in the effluent from the 5th BV were 65.5%, 22%, and 12.5%, respectively.

[0064] Example 2

[0065] This example uses column adsorption separation technology to separate Co and Li metals from a binary lithium cobalt oxide cathode material mixture. 10.0 g of amination-modified polyacrylonitrile fiber was accurately weighed using an electronic balance and soaked in deionized water at 25 °C for 12 h to ensure complete wetting. The soaked adsorption fiber was then packed into an adsorption column, filling the entire column length. During packing, the fiber was continuously compressed using a glass rod to minimize gaps between fibers. The concentration of the lithium cobalt oxide cathode material mixture was 10 mmol / L, and the peristaltic pump power was adjusted to 1.0 rpm. After the reaction, 0.2 mL of the solution was transferred to a 10 mL centrifuge tube using a 0.2 mL pipette and diluted 50 times. After adsorption, the entire sample solution in the adsorption column and inlet / outlet tubing was drained. The sample solution was then replaced with 0.2 mol / L nitric acid to elute the metals adsorbed on the fiber. After the reaction, 0.2 mL of the solution was transferred to a 10 mL centrifuge tube using a 0.2 mL pipette and diluted 50 times. The concentration of metal ions in the solution was determined using ICP-OES.

[0066] The results are as follows Figure 4 As shown, where according to Figure 4 As shown in Figure (a), the fiber essentially does not adsorb Li. The concentration of Li in the effluent after the 3rd BV is roughly equal to that in the injection solution, with a C / C0 ratio of 0.99. Co and Li begin to separate at the 2nd BV, and Co appears in the effluent after the 16th BV. The separation range of Co-Li during adsorption reaches 15 BV, and the entire adsorption process reaches adsorption equilibrium at approximately 45 BV, with a Li recovery rate of 99.1%. Figure 4 As shown in Figure (b), the separation effect of Co and Li was best at 6 BV, with the separation factor being the highest during the entire elution process, and the Co content in the effluent was highest at this time. 2+ The concentration of Co was the highest, the entire elution process ended within 15 BV, the column volume consumed was small, and the recovery rate of Co was 99.6%. In summary, the fiber exhibited good performance in the adsorption and separation of Co-Li in lithium cobalt oxide cathode materials, and column adsorption separation technology can achieve efficient separation of Co-Li.

[0067] Example 3

[0068] This example uses column adsorption separation technology to separate Mn and Li metals from a binary lithium manganese oxide cathode material mixture. 10.0 g of amination-modified polyacrylonitrile fiber was accurately weighed using an electronic balance and soaked in deionized water at 25 °C for 12 h to ensure complete wetting. The soaked adsorption fiber was then packed into an adsorption column, filling the entire column length. During packing, the fiber was continuously compressed using a glass rod to minimize gaps between fibers. The concentration of the lithium manganese oxide cathode material mixture was 10 mmol / L, and the peristaltic pump was adjusted to 1.0 rpm. The sample solution was collected using an automatic collector. After the reaction, 0.2 mL of the solution was taken using a 0.2 mL pipette and placed in a 10 mL centrifuge tube for 50-fold dilution. After adsorption was complete, the entire sample solution in the adsorption column and inlet / outlet tubing was drained. The sample solution was then replaced with 0.2 mol / L nitric acid to elute the metals adsorbed on the fiber. After the reaction was complete, 0.2 mL of the solution was transferred to a 10 mL centrifuge tube using a 0.2 mL pipette and diluted 50 times. The concentration of metal ions in the solution was determined using ICP-OES. The test results are shown below. Figure 5 As shown in the figure, the fiber does not adsorb Li at all. The concentration of Li in the effluent at 4 BV is essentially the same as that in the injection solution, with a C / C0 greater than 1.0. Mn and Li begin to separate at 2 BV, and Mn begins to appear in the effluent after 15 BV. The separation range of Mn-Li during adsorption is 13 BV, and the entire adsorption process reaches adsorption equilibrium at approximately 44 BV. Figure 5 As shown in Figure (b), the separation effect of Mn and Li is better at 8-13 BV. The entire elution process ends at around 34 BV, consuming a relatively large column volume, but achieving the desired separation of the two metals. After column separation, the recovery rate of Li is 99.3%, and the recovery rate of Mn is 99.3%. In summary, the fiber exhibits good performance in the adsorption and separation of Mn and Li in lithium manganese oxide cathode materials in this invention, and the column adsorption separation technology can achieve the separation of Mn and Li.

[0069] To further verify the effect of the acidity value of the raw solution to be recovered on the separation efficiency, the following examples were conducted.

[0070] Example 4

[0071] Accurately weigh six 0.2 g portions of fiber using an electronic balance and place them in a dry place for later use. Use a 10 mL pipette to measure 30 mL of waste NCM battery cathode material (Li). + Ni 2+ Co 2+ Mn 2+A simulated mixed solution (molar ratio 1:1:1:1) was added to an Erlenmeyer flask, and the pH of the mixed solution was adjusted to 1 using 0.1 mol / L HNO3 and 0.1 mol / L NaOH solutions. The weighed adsorption fiber was placed into the Erlenmeyer flask, sealed, and labeled. The flask was then placed in a constant temperature water bath shaker at 25℃ and a shaking rate of 160 rpm for 24 h. After the reaction, the supernatant was filtered through a 0.45 μm filter membrane. 1 mL of the solution was transferred to a 10 mL centrifuge tube using a 10 mL pipette, diluted several times, and the Li content in the solution was determined using ICP-OES. + Ni 2 + Co 2+ Mn 2+ Plot the pH-C / C0 graph based on the concentration of the C0.

[0072] Example 4

[0073] First, accurately weigh 0.10~1.0 g of fiber using an electronic balance and place it in a dry place for later use. Then, use a 10 mL pipette to measure 10~30 mL of a simulated mixed solution of waste NCM battery cathode material (Li). + Ni 2+ Co 2+ Mn 2+ The molar ratio of the two components (1:1:1:1) was placed in a 50 mL glass conical flask, and the pH was adjusted to 1-6. The fiber was then placed in the conical flask, which was sealed and placed in a constant temperature shaking incubator at 25 °C and a shaking rate of 160 rpm for 24 hours. After the reaction was complete, the solution was filtered through a 0.45 μm filter membrane. 0.1-1 mL of the solution was pipetted into a 10 mL centrifuge tube, diluted several times, and the Li content in the solution was determined by ICP-OES. + Ni 2+ Co 2+ Mn 2+ The concentration of each metal was used to calculate the adsorption selectivity coefficient K of the fiber for each metal according to formula (1). d .

[0074] Partition coefficient (adsorption selectivity coefficient) K d This refers to the ratio of the concentration of solute adsorbed in a solid adsorbent to the concentration of solute remaining in the solvent at adsorption equilibrium. It reflects the distribution of each solute component between the adsorbent and solution phases, as well as the migration ability of each solute component between the two phases. A larger partition coefficient of ions on the adsorbent indicates that they are more easily adsorbed.

[0075] Allocation coefficient K d The calculation formula is as follows:

[0076] (1)

[0077] In the formula:

[0078] The initial concentration of metal ions (mg / L);

[0079] The equilibrium concentration of metal ions (mg / L);

[0080] V The volume of the solution is in L.

[0081] The mass of the fiber is expressed in grams (g).

[0082] As shown in Example 10, the adsorption selectivity coefficient (partition coefficient) K of the adsorption fiber for each metal in this invention is... d As shown in Table 1, the adsorption order of the fibers on the four metals in the mixed solution of waste ternary lithium battery cathode materials is as follows: Ni 2+ >Co 2+ >Mn 2+ >Li + This indicates that during the adsorption process, Ni 2+ It was the first to be adsorbed onto the fiber, Li + It was the last one to be adsorbed. Because of Li... + with Ni 2+ Co 2+ Mn 2+ The partition coefficients on the fibers vary greatly, thus Li can be adsorbed through the adsorption stage. + with Ni 2+ Co 2+ Mn 2+ Separation.

[0083] Table 1 Distribution coefficients of four metal ions on the amination fibers in this product

[0084]

[0085] Meanwhile, the separation factor SF is calculated using equation (2). The initial separation factors of the four metal ions on the fiber are shown in Table 2. When the separation factor SF is greater than 1, it indicates that the two can be effectively separated.

[0086] Table 2 Initial separation factors of four metal ions on fibers

[0087]

[0088] The formula for calculating the separation factor SF is as follows:

[0089] (2)

[0090] In the formula:

[0091] is the partition coefficient of metal ion A;

[0092] is the partition coefficient of metal ion B.

[0093] Example 6

[0094] The difference from Example 3 is that the pH of the mixed solution was adjusted to 2 using 0.1 mol / L HNO3 and 0.1 mol / L NaOH solutions.

[0095] Example 7

[0096] The difference from Example 3 is that the pH of the mixed solution was adjusted to 3 using 0.1 mol / L HNO3 and 0.1 mol / L NaOH solutions.

[0097] Example 8

[0098] The difference from Example 3 is that the pH of the mixed solution was adjusted to 4 using 0.1 mol / L HNO3 and 0.1 mol / L NaOH solutions.

[0099] Example 9

[0100] The difference from Example 3 is that the pH of the mixed solution was adjusted to 5 using 0.1 mol / L HNO3 and 0.1 mol / L NaOH solutions.

[0101] Example 10

[0102] The difference from Example 3 is that the pH of the mixed solution was adjusted to 6 using 0.1 mol / L HNO3 and 0.1 mol / L NaOH solutions.

[0103] The pH values ​​in Examples 5-10 were compared with the C / CO ratios of the four metal ions in the system after adsorption treatment, and the results are as follows: Figure 6 As shown, by Figure 6 It can be seen that the separation effect of the four metal ions is poor at low or high pH values, especially the separation effect between transition metals nickel and manganese. This may be because Ni, Co, and Mn are all transition metals with similar properties, resulting in similar adsorption capacities of the fibers for Ni, Co, and Mn. When the pH of the mixed solution is 2 and 4, Li + Ni 2+ Co 2+ Mn 2+The separation effect between them is very good, and effective separation can also be achieved between the three transition metals nickel, cobalt, and manganese. However, when the pH is too high, Ni... 2+ Co 2+ Mn 2+ Some precipitation may occur, which is not conducive to adsorption separation. Therefore, the pH of the mixed solution was adjusted to 2 in subsequent column chromatography separation studies. It is worth noting that effective separation and recovery of lithium ions can be achieved within a pH range of 2 to 6 for the mixed solution.

[0104] Example 11

[0105] This embodiment investigates the effect of different injection solution concentrations on fiber adsorption of Li. + Ni 2+ Co 2+ Mn 2+ The effect of four metal ion separation efficiency was investigated. First, fully wetted adsorption fibers were packed into the adsorption column. Simulated mixed solutions of waste NCM battery cathode material were diluted several times, and samples were injected using a peristaltic pump with a fixed pump power. The solutions were collected using an automatic collector. After the reaction, a certain volume of solution was transferred to a 10 mL centrifuge tube using a 1 or 0.2 mL pipette, diluted several times, and the Li content in the solution was determined using ICP-OES. + Ni 2+ Co 2+ Mn 2+ The concentrations were determined, and a BV-C / C0 plot was plotted. The effect of different injection solution concentrations on the adsorption and separation of four metal ions in the fiber adsorption mixed solution was analyzed to determine the optimal injection solution concentration. The injection concentration ranged from 0.1 to 20 mmol / L, with the optimal concentration being 10 mmol / L. The separation effect of metal ions at this concentration is shown in [Figure showing the results]. Figure 7 As shown in the figure, at an injection concentration of 10 mmol / L, Ni and Co, two metals with similar properties, not only begin to separate at a minimum of 12 BV, but also reach adsorption equilibrium at 30 BV. Meanwhile, the adsorption curves at injection concentrations of [missing information] show that Li begins to elute at 2 BV and reaches adsorption equilibrium at 3 BV, with a C / C0 ratio close to 1.0. This indicates that Li is less competitive than Ni, Co, and Mn, and the fiber hardly adsorbs Li.

[0106] Example 12

[0107] To investigate the effect of fiber-packed adsorption column length on adsorption separation, the following examples were conducted. The experiments explored the effect of different fiber-packed column lengths on the adsorption of Li while keeping the injection solution concentration and flow rate (peristaltic pump power) constant. + Ni 2+Co 2+ Mn 2+ The effect of four metal ion separation efficiency was investigated. Fully moistened adsorption fibers were packed into an adsorption column, with the fiber adsorption column length ranging from 1 / 5 of the column length to full column. During packing, the fibers were continuously compressed using a glass rod to minimize the gaps between the fibers. The concentration of the simulated mixed solution was fixed using waste NCM battery cathode material, and the peristaltic pump power was maintained. The sample solution was collected using an automatic collector. After the reaction, 0.2 mL of the solution was taken using a 0.2 mL pipette and placed in a 10 mL centrifuge tube. After diluting 50 times, the Li in the solution was determined using ICP-OES. + Ni 2+ Co 2+ Mn 2+ The concentrations were analyzed, and a BV-C / C0 plot was plotted to examine the effect of different fiber-packed column lengths on the adsorption and separation of four metal ions in a mixed solution, thus determining the optimal fiber-packed column length and concentration. The analysis results show that full column packing is the optimal solution. The analytical results for the four metal ions under full column packing are shown in the figure. Figure 8 As shown in the figure, when the fiber-filled column length is the full column length, Li has a better separation effect from the other three metals. The liquid effluent from the second to the sixth column volume is all Li. This indicates that the more volume of amination polyacrylonitrile fiber is filled in the adsorption column, the better the adsorption and separation effect of the fiber on Li and Ni, Co and Mn will be.

[0108] Example 13

[0109] While keeping the injection solution concentration and the length of the fiber-packed adsorption column constant, this embodiment investigated the effect of different peristaltic pump powers (injection flow rates) on the adsorption of Li by the fiber. + Ni 2+ Co 2+ Mn 2+ The effects of four metal ion separation efficiency were investigated. Specifically, fully wetted adsorption fibers were first packed into the adsorption column (the fiber mass and packing method were the same as described above). A simulated mixed solution concentration of waste NCM battery cathode material was fixed. A peristaltic pump was used for injection to vary the flow rate of the injected solution. The effluent solution was collected using an automatic collector. After the reaction, 0.2 mL of the solution was transferred to a 10 mL centrifuge tube using a 0.2 mL pipette. After diluting 50 times, the Li in the solution was determined using ICP-OES. + Ni 2+ Co 2+ Mn 2+ The concentrations were determined, and a BV-C / C0 plot was plotted. The effect of different peristaltic pump powers on the adsorption and separation of four metal ions in the fiber adsorption mixed solution was analyzed to determine the optimal peristaltic pump power. In the experiment, the peristaltic pump power was set to 1.0. The test results are shown in [Figure number missing]. Figure 9 ,Depend on Figure 9 As shown, when the peristaltic pump power is 1.0 rpm, the flow rate of the injected solution is moderate, and the separation effect between Li and the three metals Ni, Co, and Mn is good, with a separation range of 5 BV. The entire adsorption process reaches adsorption equilibrium at a column volume of approximately 32 BV. Ni and Co begin to separate at 12 BV, and at 2 BV, the C / C0 calculated from the Li content in the effluent reaches 0.97, which is approximately equivalent to the Li concentration in the injected solution. This indicates that at this point, almost no Li is adsorbed on the fiber, and Li has been replaced by the other three metals.

[0110] Analysis of Examples 4-13 shows that during the adsorption process, Li separates from Ni, Co, and Mn in the second BV, and there is a separation interval of 5 BV. The recovery rate of Li is 99.4% as calculated by formula (3).

[0111] The recovery rate R is calculated using the following formula:

[0112] (3)

[0113] In the formula: The mass of the target component in the solution after separation; This represents the mass of the target component in the solution before separation.

[0114] Example 14

[0115] To investigate the effect of eluent concentration on elution efficiency, the following examples were conducted:

[0116] After the fiber reaches adsorption saturation, all the sample solution in the adsorption column and inlet / outlet pipes is drained. Then, the sample solution is replaced with nitric acid to treat the Li adsorbed on the fiber. + Ni 2+ Co 2+ Mn 2+ Elution was performed to investigate the effect of different nitric acid concentrations on Li + Ni 2+ Co 2+ Mn 2+ The effect of elution efficiency. The concentration of eluting acid was set to 0.01–0.2 mol / L, and the peristaltic pump power was adjusted to 1.0 rpm. The sample solution was collected using an automatic collector. After elution (the fibers will turn pale yellow), 0.1–0.2 mL of the solution was transferred to a 10 mL centrifuge tube using a 0.2 mL pipette. After diluting 50–100 times, the Li in the solution was determined using ICP-OES. + Ni 2+ Co 2+ Mn 2+The concentration of nitric acid was determined, and a BV-C / C0 diagram was plotted to analyze the effect of different nitric acid concentrations on the elution of four metal ions adsorbed on the fiber, thus determining the optimal elution acid concentration. Results are shown below. Figure 10 , Figure 10 The concentration of nitric acid in the eluent was 0.2 mol / L. When the concentration of nitric acid was 0.2 mol / L, the separation effect among the four metal ions was the most ideal. The metals on the fiber could be completely eluted and separated in a smaller column volume of 10 BV, and the separation effect among the transition metals nickel, cobalt and manganese was also very significant. From the 1st BV to the 5th BV, Ni, Co and Mn were all separated well. Especially in the 3rd and 4th BV, the C / C0 of Ni in the effluent reached about 3.0, indicating that the concentration of Ni in the effluent was very high. At the same time, Ni, Co and Mn could be completely eluted from the fiber in a smaller column volume of 10 BV. According to formulas (3) and (4), the recovery rate of Ni in the first 5 BV was 80.2%, the recovery rate of Co was 89.8% and the recovery rate of Mn was 71.4%. The purity of Ni, Co and Mn in the effluent in the 5th BV was 65.5%, 22% and 12.5% ​​respectively.

[0117] The formula for calculating purity P is as follows:

[0118] (4)

[0119] In the formula:

[0120] This represents the mass of metal ion A in the solution after separation.

[0121] This represents the mass of metal ion B in the solution after separation.

[0122] Example 15

[0123] This embodiment performs XPS characterization analysis on the fibers after adsorption and elution in Example 1. The XPS spectrum of the adsorbed fibers is shown in [Figure 1]. Figure 11 After elution, the XPS of the fibers are shown in [the image]. Figure 12 As shown in the figure, after adsorption, Li, Ni, Co, and Mn all exhibited distinct peaks, indicating that the fiber adsorbed all four metal ions. The Li peak was weaker, the Ni peak was stronger, and the peaks of Co and Mn were weaker, indicating that the fiber adsorbed the least amount of Li, resulting in a lower Li concentration on the fiber surface. Conversely, the fiber adsorbed the most Ni, resulting in the highest Ni concentration on the fiber surface, consistent with the conclusions drawn from the adsorption process. After elution, no peaks were observed for Li, Ni, Co, or Mn, indicating that the metal ions adsorbed on the fiber surface had been completely eluted. Therefore, using fiber as the adsorbent material to separate the four metals from a ternary nickel-cobalt-manganese mixed solution via adsorption-elution is feasible.

[0124] Example 16

[0125] This embodiment tests the surface morphology of the fiber before, after, and after acid elution of the metal adsorption process in Example 1. The test results are shown in [Figure 1]. Figure 13 As shown in the figure, the fiber surface was relatively smooth before adsorbing metal ions, with a few small grooves and scratches likely due to the modification process. After adsorbing metal ions, the fiber surface morphology changed significantly; it became rougher with numerous protrusions, indicating good adsorption of metal ions. After acid elution, the adsorbed metals on the fiber were completely eluted, and the fiber surface became smoother compared to its original state, effectively eluting the adsorbed metal ions.

[0126] This invention primarily employs chromatographic separation technology, using diethylenetriamine-aminated polyacrylonitrile fiber as the adsorption carrier, to separate and recover valuable metals Li, Ni, Co, and Mn from waste ternary lithium-ion battery cathode materials, and to separate and recover Co-Li from binary lithium cobalt oxide cathode materials and Mn-Li from binary lithium manganese oxide cathode materials. During the adsorption-elution process in the multi-component column system, under optimal adsorption and elution conditions, the recovery rates were 99.4% for Li, 80.2% for Ni, 89.8% for Co, and 71.4% for Mn. The purities of Ni, Co, and Mn in the 5th batch volume effluent were 65.5%, 22%, and 12.5%, respectively. In the binary lithium cobalt oxide system, under optimal adsorption and elution conditions, the recovery rate of Li was 96.1% and the recovery rate of Co was 99.6%. In the binary lithium manganese oxide system, under optimal adsorption and elution conditions, the recovery rate of Li was 96.4% and the recovery rate of Mn was 99.3%.

[0127] Example 17

[0128] A method for recovering metallic lithium from waste lithium battery cathode materials includes the following steps:

[0129] S1: Dissolve the cathode material of the ternary lithium-ion battery to be recycled in nitric acid solution to obtain the raw solution to be recycled;

[0130] S2: Inject the original solution to be recovered into a packed column, wherein the packed column is adiethylenetriamine-aminated modified polyacrylonitrile fiber, and collect the eluent up to six column volumes.

[0131] The column volume of the packed column is 10 cm³. 3 The packing volume of the chromatographic column is 8 cm³. 3 .

[0132] Preferably, before injecting the original solution to be recovered into the packed column, the pH value of the original solution to be recovered is adjusted to 2, and the concentration of the original solution to be recovered is adjusted to 0.1 mmol / L.

[0133] The flow rate of the original solution to be recovered in the packed column was 0.05 mL / min.

[0134] S3: Replace the packing column and repeat step S2 until all samples to be recovered are processed, thus completing the recovery of metallic lithium from the waste lithium battery materials.

[0135] The packed column was replaced with a packed column that had been eluted with an eluent. The eluent used was 0.01 mol / L nitric acid. The eluent was used for 10 column volumes.

[0136] Example 18

[0137] A method for recovering metallic lithium from waste lithium battery cathode materials includes the following steps:

[0138] S1: Dissolve the positive electrode material of the lithium cobalt oxide battery to be recycled in nitric acid solution to obtain the raw solution to be recycled;

[0139] S2: Inject the original solution to be recovered into a packed column, wherein the packed column is adiethylenetriamine amination modified polyacrylonitrile fiber, and collect the eluent within three column volumes;

[0140] The column volume of the packed column is 20 cm³. 3 The packing volume of the chromatographic column is 15 cm³. 3 .

[0141] Preferably, before injecting the original solution to be recovered into the packed column, the pH value of the original solution to be recovered is adjusted to 6, and the concentration of the original solution to be recovered is adjusted to 20 mmol / L.

[0142] The flow rate of the original solution to be recovered in the packed column was 0.60 mL / min.

[0143] S3: Replace the packing column and repeat step S2 until all samples to be recovered are processed, thus completing the recovery of metallic lithium from the waste lithium battery materials.

[0144] The packed column was replaced with a packed column treated with elution buffer. The elution buffer was 0.2 mol / L nitric acid. The elution buffer was used for 12 column volumes.

[0145] Example 19

[0146] A method for recovering metallic lithium from waste lithium battery cathode materials includes the following steps:

[0147] S1: Dissolve the positive electrode material of the lithium manganese oxide battery to be recycled in nitric acid solution to obtain the raw solution to be recycled;

[0148] S2: Inject the original solution to be recovered into a packed column, wherein the packed column is adiethylenetriamine amination modified polyacrylonitrile fiber, and collect up to five column volumes of effluent.

[0149] The column volume of the packed column is 15 cm³. 3 The packing volume of the chromatographic column is 15 cm³. 3 .

[0150] Preferably, before injecting the raw solution to be recovered into the packed column, the pH value of the raw solution to be recovered is adjusted to 4, the concentration of the raw solution to be recovered is adjusted to 10 mmol / L, and the flow rate of the raw solution to be recovered in the packed column is 0.10 mL / min.

[0151] S3: Replace the packing column and repeat step S2 until all samples to be recovered are processed, thus completing the recovery of metallic lithium from the waste lithium battery materials.

[0152] The packed column was replaced with a packed column treated with elution buffer. The elution buffer was 0.1 mol / L nitric acid. The elution buffer was used for 11 column volumes.

[0153] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0154] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for recovering metallic lithium from waste lithium battery cathode materials, characterized in that, Includes the following steps: S1: Dissolve the positive electrode material of the lithium-ion battery to be recycled in nitric acid solution to obtain the raw solution to be recycled; S2: Inject the original solution to be recovered into a packed column, wherein the packed column is adiethylenetriamine-aminated modified polyacrylonitrile fiber, and collect the eluent up to six column volumes. The preparation process of the diethylenetriamine amination modified polyacrylonitrile fiber is as follows: A certain volume of diethylenetriamine was added to a high-pressure reactor, and a certain mass of polyacrylonitrile fiber was placed in the system and stirred evenly to make the ratio of diethylenetriamine to polyacrylonitrile fiber 5 mL: 1 g. Then, sodium carbonate solution was added and stirred evenly, and the reaction system was reacted at 115 °C for 5 h to obtain the diethylenetriamine amination modified polyacrylonitrile fiber; wherein, the ratio of polyacrylonitrile fiber to sodium carbonate solution was 1 g: 1 mL, and the concentration of sodium carbonate solution was 0.01 g / mL; S3: Replace the packing column and repeat step S2 until all samples to be recovered are processed, thus completing the recovery of metallic lithium from the waste lithium battery cathode material.

2. A method for recovering metallic lithium from waste lithium battery cathode materials according to claim 1, characterized in that, The column volume of the packed column is 10-20 cm³. 3 .

3. A method for recovering metallic lithium from waste lithium battery cathode materials according to claim 1, characterized in that, The packing volume of the chromatographic column is 8-15 cm³. 3 .

4. The method for recovering metallic lithium from waste lithium battery cathode materials according to claim 1, characterized in that, Before injecting the original solution to be recovered into the packed column, adjust the pH of the original solution to be recovered to 2-6.

5. A method for recovering metallic lithium from waste lithium battery cathode materials according to claim 1, characterized in that, Before injecting the original solution to be recovered into the packed column, adjust the concentration of the original solution to be recovered to 0.1~20 mmol / L.

6. A method for recovering metallic lithium from waste lithium battery cathode materials according to claim 1, characterized in that, The flow rate of the original solution to be recovered in the packed column is 0.05~0.60 mL / min.

7. The method for recovering metallic lithium from waste lithium battery cathode materials according to claim 1, characterized in that, In step S2, the effluent within the first three column volumes is collected.

8. The method for recovering metallic lithium from waste lithium battery cathode materials according to claim 1, characterized in that, In step S3, the packed column is replaced with a packed column that has not undergone adsorption treatment or a packed column that has been eluted with elution solution.

9. A method for recovering metallic lithium from waste lithium battery cathode materials according to claim 8, characterized in that, The eluent is nitric acid with a concentration of 0.01~0.2 mol / L.

10. A method for recovering metallic lithium from waste lithium battery cathode materials according to claim 8, characterized in that, During elution, the eluent used is 10 to 12 column volumes.

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