A method for selectively recycling lithium and cobalt from waste lithium-ion battery cathode material, lithium cobalt oxide.

Abstract

This invention provides a method for selectively recovering lithium and cobalt from waste lithium-ion battery cathode material, lithium cobalt oxide, belonging to the field of lithium-ion battery metal recycling. The method includes the following steps: mixing chloroacetic acid and tetrabutylammonium chloride to form a leaching solvent; then adding the waste lithium cobalt oxide cathode material and oxalic acid to this solvent to selectively leach cobalt, with lithium precipitating as oxalate; adding water to obtain cobalt oxalate dihydrate precipitate; evaporating the water from the solvent to obtain a regenerated solvent, which is recycled as a leaching solvent. This method, without using strong acids, utilizes the leaching solvent formed by chloroacetic acid and tetrabutylammonium chloride to selectively dissolve metals in waste lithium-ion battery cathodes, recovering lithium and cobalt stepwise; the process is simple, can recover lithium and cobalt under mild conditions, and is easily regenerated.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery metal recycling, and in particular relates to a method for selectively recycling lithium and cobalt from waste lithium battery cathode material lithium cobalt oxide. Background Technology

[0002] As the world's largest consumer of new energy vehicles, China's rapid iteration and upgrading of new energy vehicles has accelerated the retirement of discarded lithium-ion batteries. Lithium-ion battery cathode materials are rich in valuable metals such as lithium and cobalt. If these are not effectively recycled, it will not only lead to resource waste but also cause environmental pollution. Therefore, the efficient recovery of valuable metals from discarded lithium-ion batteries is crucial.

[0003] Industrially, the recycling of valuable metals from waste lithium batteries mainly involves two methods: pyrometallurgical recovery and hydrometallurgical recovery. Pyrometallurgy utilizes extremely high temperatures (exceeding 1000℃) to break down the structure of the lithium battery cathode material, recovering the metals in the form of alloys. This results in significant carbon dioxide emissions and requires substantial energy consumption. Compared to pyrometallurgy, hydrometallurgy offers unique advantages such as high selectivity and high leaching rates. Specifically, it involves dissolving waste cathode material in acidic or alkaline solutions, followed by concentration, separation, and resynthesis, thereby obtaining high-purity products with less energy consumption. However, traditional hydrometallurgical processes use strong acids and alkalis as leaching agents, which can cause equipment corrosion, generate large amounts of wastewater and toxic gases, polluting the environment and posing health risks. Therefore, low-toxicity and low-corrosion organic leaching agents, such as citric acid and tartaric acid, have attracted considerable interest from researchers. Although organic leaching agents are more environmentally friendly, their cost is significantly higher than that of inorganic leaching agents. Furthermore, because organic leaching solutions have lower acidity or alkalinity, higher leaching temperatures are required. Therefore, there is an urgent need to develop an economical, environmentally friendly, and energy-efficient method to recover useful metals from waste lithium batteries.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a method for selectively recovering lithium and cobalt from waste lithium-ion battery cathode material lithium cobalt oxide. Under conditions without the use of strong acids, the method utilizes a solvent formed by chloroacetic acid and tetrabutylammonium chloride to selectively dissolve the metals in the waste lithium-ion battery cathode, thereby recovering lithium and cobalt in steps. This method has a simple process, can achieve the recovery and utilization of lithium and cobalt under mild conditions, and is easy to regenerate.

[0006] To achieve the above objectives, the present invention adopts the following specific technical solution:

[0007] A method for selectively recovering lithium and cobalt from waste lithium-ion battery cathode material lithium cobalt oxide includes the following steps: first, preparing a leaching solvent by mixing chloroacetic acid and tetrabutylammonium chloride; second, using the solvent to leach cobalt from the waste lithium-ion battery cathode material lithium cobalt oxide, precipitating lithium oxalate; and precipitating cobalt oxalate dihydrate.

[0008] Furthermore, the process of leaching cobalt and precipitating lithium oxalate from the waste lithium cobalt oxide cathode material involves adding the waste lithium cobalt oxide cathode material to a prepared solvent, adding oxalic acid, heating and stirring to selectively leach cobalt, and precipitating lithium as oxalate; then filtering to obtain solid lithium oxalate and a cobalt-containing leachate.

[0009] Preferably, the solvent is prepared by mixing chloroacetic acid and tetrabutylammonium chloride and heating and stirring. The choice of solvent is crucial to this invention; it must be able to dissolve lithium and cobalt metal ions and achieve subsequent selective separation. Chloroacetic acid is a strong organic acid, which is beneficial for the dissolution of the cathode material. Tetrabutylammonium chloride provides chloride ions and has a strong coordination effect, which can combine with cobalt metal, thus facilitating dissolution. After mixing chloroacetic acid and tetrabutylammonium chloride, salts can be formed with lithium and cobalt, dissolving both metals. When oxalic acid is added to the solvent, the formed lithium oxalate is insoluble in the solvent, causing lithium oxalate to precipitate. When water is added to the filtered leachate, cobalt oxalate dihydrate is formed. This hydrate is insoluble in the aqueous solution of the solvent, thus precipitating out and achieving cobalt recovery. Compared to traditional wet recovery methods using strong acids such as sulfuric acid and nitric acid, although these can dissolve the two metals, selective separation cannot occur, especially for lithium. If a solvent with too weak an acidity is used, it is difficult to dissolve the two metals, and no separation effect can be achieved.

[0010] Furthermore, the heating temperature for the mixture of chloroacetic acid and tetrabutylammonium chloride is 65–75°C; in some embodiments of the present invention, the heating temperature can be any value between 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, and 75°C. Heating the mixture of chloroacetic acid and tetrabutylammonium chloride rapidly forms a solvent; without heating, a long mixing time is required, and the solvent's ability to leach the metal cannot be fully realized.

[0011] Preferably, the molar ratio of chloroacetic acid to tetrabutylammonium chloride is 2.8:1 to 3.2:1. In some embodiments of the present invention, the molar ratio of chloroacetic acid to tetrabutylammonium chloride can be any value between 2.8:1, 2.9:1, 3:1, 3.1:1, and 3.2:1. If the amount of chloroacetic acid is low, the solvent viscosity is high. For example, when the molar ratio of chloroacetic acid to tetrabutylammonium chloride is 1:1, the solvent viscosity at room temperature is as high as 992 mPa·s, and the acidity also decreases, which is not conducive to the dissolution of the positive electrode material. When more chloroacetic acid is added, the concentration of tetrabutylammonium chloride decreases, and the chloride ion concentration decreases, which is not conducive to the complexation of chloride ions with metal ions, thus hindering dissolution and reducing the leaching rate. At the same time, excessive chloroacetic acid content is not conducive to the precipitation of lithium oxalate.

[0012] Furthermore, the amount of oxalic acid added is 20–40 g / L.

[0013] The purpose of adding oxalic acid here is twofold. First, it protects the leaching solvent; oxalic acid acts as a reducing agent, preventing the solvent from being oxidized by the high-valence cobalt in the lithium cobalt oxide powder. Second, it causes lithium to form oxalate precipitate, facilitating the separation of lithium and cobalt. Adding too much oxalic acid reduces the solubility of cobalt, hindering the dissolution of large quantities of metal and wasting resources. Adding too little oxalic acid, on the one hand, fails to cause lithium to form a large amount of lithium oxalate precipitate, reducing the recovery rate; on the other hand, it cannot completely reduce the high-valence cobalt, failing to adequately protect the leaching solvent; and it also prevents cobalt from forming a large amount of cobalt oxalate, which is detrimental to subsequent cobalt recovery. In some embodiments of the present invention, the amount of oxalic acid added can be any value between 20 g / L, 21 g / L, 22 g / L, 23 g / L, 24 g / L, 25 g / L, 26 g / L, 27 g / L, 28 g / L, 29 g / L, 30 g / L, 31 g / L, 32 g / L, 33 g / L, 34 g / L, 35 g / L, 36 g / L, 37 g / L, 38 g / L, 39 g / L, and 40 g / L.

[0014] Further, the solid-liquid ratio of the waste lithium cobalt oxide powder to the leaching solvent is 10–20 g / L. In some embodiments of the present invention, the solid-liquid ratio can be any value between 10 g / L, 11 g / L, 12 g / L, 13 g / L, 14 g / L, 15 g / L, 16 g / L, 17 g / L, 18 g / L, 19 g / L, and 20 g / L.

[0015] Furthermore, the temperature at which the waste lithium cobalt oxide powder is heated and leached with the leaching solvent is 90–100°C. In some embodiments of the present invention, the heating temperature can be any value between 90°C, 91°C, 92°C, 93°C, 94°C, 95°C, 96°C, 97°C, 98°C, 99°C, and 100°C.

[0016] Preferably, the stirring time is 5 to 7 hours.

[0017] Furthermore, the cobalt oxalate dihydrate precipitate is obtained by adding water to the cobalt-containing leachate, filtering, and then obtaining a solid precipitate of cobalt oxalate dihydrate and a leachate.

[0018] Preferably, the amount of water added is equal to the volume of the cobalt-containing leachate.

[0019] The leaching agent, after evaporating the water from the leachate, can be reused to leach lithium battery cathode materials.

[0020] Furthermore, the leaching agent, which contains a small amount of residual metal ions, will participate in the recovery process together with the newly added lithium cobalt oxide powder, preventing gradual accumulation. Therefore, the recycling of the leaching agent can achieve better metal recovery results.

[0021] Compared with existing technologies, this invention optimizes the metal recovery process of traditional waste lithium cobalt oxide battery cathode materials by using chloroacetic acid and tetrabutylammonium chloride as leaching solvents. It recovers waste lithium cobalt oxide battery cathode material powder under mild conditions and is easy to operate. The solvent has low pollution, is easily regenerated, and can be recycled. Furthermore, lithium and cobalt can be 100% recovered during the solvent recycling process. Attached Figure Description

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

[0023] Figure 1 This is a process flow diagram of the present invention.

[0024] Figure 2 The image shows the X-ray powder diffraction (XRD) pattern of the lithium oxalate product recovered in this embodiment of the invention.

[0025] Figure 3 The image shows the X-ray powder diffraction (XRD) pattern of the cobalt oxalate dihydrate product recovered in this embodiment of the invention. Detailed Implementation

[0026] As used in this article:

[0027] "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0028] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0029] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0030] The technical solution of the present invention will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used that do not specify the manufacturer are all conventional products that can be purchased commercially. In the present invention, there are no special limitations on the form of the reactor.

[0031] Example 1

[0032] A method for selectively recycling lithium and cobalt from waste lithium-ion battery cathode materials, such as Figure 1 As shown, it includes the following steps:

[0033] (1) Mix 33.19g of chloroacetic acid with 30.57g of tetrabutylammonium chloride (3:1 molar ratio), heat to 70°C, and stir to form an leaching solvent.

[0034] (2) Weigh 0.8g of waste lithium-ion battery cathode material lithium cobalt oxide powder (mass content of each element: Co: 60.21wt%; Li: 6.94wt%), add it to 50mL of the leaching solvent obtained in step (1), then add 1.6g of oxalic acid, heat and stir at 100℃ for 7h to obtain a mixture containing lithium and cobalt. At this time, cobalt will leach into the solvent, and lithium will precipitate in the form of oxalate.

[0035] (3) The mixture obtained in step (2) was filtered to obtain a leachate and lithium oxalate precipitate. The lithium element was analyzed using an ICP-OES instrument (ICAP6300, USA), and the lithium element recovery rate was calculated to be 98%. The obtained leachate was then used for the next step.

[0036] (4) Add 50 mL of water to the leachate obtained in step (3), filter, and obtain cobalt oxalate dihydrate precipitate and leachate aqueous solution. Dry the precipitate to obtain cobalt oxalate dihydrate solid. Analyze the cobalt element in the precipitate using an ICP-OES instrument, and the cobalt element recovery rate is calculated to be 93%.

[0037] (5) Collect the leachate aqueous solution from step (4), evaporate the water, and obtain the regenerated leachate.

[0038] Steps (2) to (5) were repeated five times using the regenerated leaching agent, and the recovery rate of the recovered metal elements was analyzed using an ICP-OES instrument each time. In the first two recoveries, both lithium and cobalt achieved 100% recovery. In the third recovery, the lithium recovery rate was 98%, and the cobalt recovery rate was 100%. In the fourth recovery, the lithium recovery rate was 97%, and the cobalt recovery rate was 100%. In the fifth recovery, the lithium recovery rate was 100%, and the cobalt recovery rate was 99%.

[0039] Example 2

[0040] A method for selectively recycling lithium and cobalt from waste lithium-ion battery cathode materials, such as Figure 1 As shown, it includes the following steps:

[0041] (1) Mix 33.19g of chloroacetic acid with 30.57g of tetrabutylammonium chloride (3:1 molar ratio), heat to 70°C, and stir to form an leaching solvent.

[0042] (2) Weigh 1g of waste lithium-ion battery cathode material lithium cobalt oxide powder (mass content of each element: Co: 60.21wt%; Li: 6.94wt%), add it to 50mL of the leaching solvent obtained in step (1), then add 2g of oxalic acid, heat and stir at 100℃ for 7h to obtain a mixture containing lithium and cobalt. At this time, cobalt will leach into the solvent, and lithium will precipitate in the form of oxalate.

[0043] (3) The mixture obtained in step (2) was filtered to obtain a leachate and lithium oxalate precipitate. The lithium element was analyzed using an ICP-OES instrument (ICAP6300, USA), and the lithium element recovery rate was calculated to be 96%. The obtained leachate was then used for the next step.

[0044] (4) Add 50 mL of water to the leachate obtained in step (3), filter, and obtain cobalt oxalate dihydrate precipitate and leachate aqueous solution. Dry the precipitate to obtain cobalt oxalate dihydrate solid. Analyze the cobalt element in the precipitate using an ICP-OES instrument, and the cobalt element recovery rate is calculated to be 90%.

[0045] (5) Collect the leachate aqueous solution from step (4), evaporate the water, and obtain the regenerated leachate.

[0046] Example 3

[0047] A method for selectively recycling lithium and cobalt from waste lithium-ion battery cathode materials, such as Figure 1 As shown, it includes the following steps:

[0048] (1) Mix 33.19g of chloroacetic acid with 30.57g of tetrabutylammonium chloride (3:1 molar ratio), heat to 70°C, and stir to form an leaching solvent.

[0049] (2) Weigh 0.5g of waste lithium-ion battery cathode material lithium cobalt oxide powder (mass content of each element: Co: 60.21wt%; Li: 6.94wt%), add it to 50mL of the leaching solvent obtained in step (1), then add 1g of oxalic acid, heat and stir at 100℃ for 7h to obtain a mixture containing lithium and cobalt. At this time, cobalt will leach into the solvent, and lithium will precipitate in the form of oxalate.

[0050] (3) The mixture obtained in step (2) was filtered to obtain a leachate and lithium oxalate precipitate. The lithium element was analyzed using an ICP-OES instrument (ICAP6300, USA), and the lithium element recovery rate was calculated to be 98%. The obtained leachate was then used for the next step.

[0051] (4) Add 50 mL of water to the leachate obtained in step (3), filter, and obtain cobalt oxalate dihydrate precipitate and leachate aqueous solution. Dry the precipitate to obtain cobalt oxalate dihydrate solid. Analyze the cobalt element in it using an ICP-OES instrument, and the cobalt element recovery rate is calculated to be 92%.

[0052] (5) Collect the leachate aqueous solution from step (4), evaporate the water, and obtain the regenerated leachate.

[0053] Example 4

[0054] A method for selectively recycling lithium and cobalt from waste lithium-ion battery cathode materials, such as Figure 1 As shown, it includes the following steps:

[0055] (1) Mix 33.19g of chloroacetic acid with 30.57g of tetrabutylammonium chloride (3:1 molar ratio), heat to 70°C, and stir to form an leaching solvent.

[0056] (2) Weigh 0.8g of waste lithium-ion battery cathode material lithium cobalt oxide powder (mass content of each element: Co: 60.21wt%; Li: 6.94wt%), add it to 50mL of the leaching solvent obtained in step (1), then add 1.6g of oxalic acid, heat and stir at 90℃ for leaching for 7h, to obtain a mixture containing lithium and cobalt. At this time, cobalt will leach into the solvent, and lithium will precipitate in the form of oxalate.

[0057] (3) The mixture obtained in step (2) was filtered to obtain a leachate and lithium oxalate precipitate. The lithium element was analyzed using an ICP-OES instrument (ICAP6300, USA), and the lithium element recovery rate was calculated to be 94%. The obtained leachate was then used for the next step.

[0058] (4) Add 50 mL of water to the leachate obtained in step (3), filter, and obtain cobalt oxalate dihydrate precipitate and leachate aqueous solution. Dry the precipitate to obtain cobalt oxalate dihydrate solid. Analyze the cobalt element in the precipitate using an ICP-OES instrument, and the cobalt element recovery rate is calculated to be 88%.

[0059] (5) Collect the leachate aqueous solution from step (4), evaporate the water, and obtain the regenerated leachate.

[0060] Example 5

[0061] A method for selectively recycling lithium and cobalt from waste lithium-ion battery cathode materials, such as Figure 1 As shown, it includes the following steps:

[0062] (1) Mix 33.19g of chloroacetic acid with 30.57g of tetrabutylammonium chloride (3:1 molar ratio), heat to 70°C, and stir to form an leaching solvent.

[0063] (2) Weigh 0.8g of waste lithium-ion battery cathode material lithium cobalt oxide powder (mass content of each element: Co: 60.21wt%; Li: 6.94wt%), add it to 50mL of the leaching solvent obtained in step (1), then add 1.6g of oxalic acid, heat and stir at 100℃ for 5h to obtain a mixture containing lithium and cobalt. At this time, cobalt will leach into the solvent, and lithium will precipitate in the form of oxalate.

[0064] (3) The mixture obtained in step (2) was filtered to obtain a leachate and lithium oxalate precipitate. The lithium element was analyzed using an ICP-OES instrument (ICAP6300, USA), and the lithium element recovery rate was calculated to be 95%. The obtained leachate was then used for the next step.

[0065] (4) Add 50 mL of water to the leachate obtained in step (3), filter, and obtain cobalt oxalate dihydrate precipitate and leachate aqueous solution. Dry the precipitate to obtain cobalt oxalate dihydrate solid. Analyze the cobalt element in the precipitate using an ICP-OES instrument, and the cobalt element recovery rate is calculated to be 90%.

[0066] (5) Collect the leachate aqueous solution from step (4), evaporate the water, and obtain the regenerated leachate.

[0067] Example 6

[0068] A method for selectively recycling lithium and cobalt from waste lithium-ion battery cathode materials, such as Figure 1 As shown, it includes the following steps:

[0069] (1) Mix 29.11g of chloroacetic acid with 30.57g of tetrabutylammonium chloride (2.8:1 molar ratio), heat to 70°C, and stir to form an leaching solvent.

[0070] (2) Weigh 0.8g of waste lithium-ion battery cathode material lithium cobalt oxide powder (mass content of each element: Co: 60.21wt%; Li: 6.94wt%), add it to 50mL of the leaching solvent obtained in step (1), then add 1.6g of oxalic acid, heat and stir at 100℃ for 7h to obtain a mixture containing lithium and cobalt. At this time, cobalt will leach into the solvent, and lithium will precipitate in the form of oxalate.

[0071] (3) The mixture obtained in step (2) was filtered to obtain a leachate and lithium oxalate precipitate. The lithium element was analyzed using an ICP-OES instrument (ICAP6300, USA), and the lithium element recovery rate was calculated to be 97%. The obtained leachate was then used for the next step.

[0072] (4) Add 50 mL of water to the leachate obtained in step (3), filter, and obtain cobalt oxalate dihydrate precipitate and leachate aqueous solution. Dry the precipitate to obtain cobalt oxalate dihydrate solid. Analyze the cobalt element in the precipitate using an ICP-OES instrument, and the cobalt element recovery rate is calculated to be 91%.

[0073] (5) Collect the leachate aqueous solution from step (4), evaporate the water, and obtain the regenerated leachate.

[0074] Example 7

[0075] A method for selectively recycling lithium and cobalt from waste lithium-ion battery cathode materials, such as Figure 1 As shown, it includes the following steps:

[0076] (1) Mix 37.42g of chloroacetic acid with 30.57g of tetrabutylammonium chloride (3.2:1 molar ratio), heat to 70°C, and stir to form an leaching solvent.

[0077] (2) Weigh 0.8g of waste lithium-ion battery cathode material lithium cobalt oxide powder (mass content of each element: Co: 60.21wt%; Li: 6.94wt%), add it to 50mL of the leaching solvent obtained in step (1), then add 1.6g of oxalic acid, heat and stir at 100℃ for 7h to obtain a mixture containing lithium and cobalt. At this time, cobalt will leach into the solvent, and lithium will precipitate in the form of oxalate.

[0078] (3) The mixture obtained in step (2) was filtered to obtain a leachate and lithium oxalate precipitate. The lithium element was analyzed using an ICP-OES instrument (ICAP6300, USA), and the lithium element recovery rate was calculated to be 97%. The obtained leachate was then used for the next step.

[0079] (4) Add 50 mL of water to the leachate obtained in step (3), filter, and obtain cobalt oxalate dihydrate precipitate and leachate aqueous solution. Dry the precipitate to obtain cobalt oxalate dihydrate solid. Analyze the cobalt element in the precipitate using an ICP-OES instrument, and the cobalt element recovery rate is calculated to be 90%.

[0080] (5) Collect the leachate aqueous solution from step (4), evaporate the water, and obtain the regenerated leachate.

[0081] Example 8

[0082] A method for selectively recycling lithium and cobalt from waste lithium-ion battery cathode materials, such as Figure 1 As shown, it includes the following steps:

[0083] (1) Mix 33.19g of chloroacetic acid with 30.57g of tetrabutylammonium chloride (3:1 molar ratio), heat to 70°C, and stir to form an leaching solvent.

[0084] (2) Weigh 0.8g of waste lithium-ion battery cathode material lithium cobalt oxide powder (mass content of each element: Co: 60.21wt%; Li: 6.94wt%), add it to 50mL of the leaching solvent obtained in step (1), then add 1.4g of oxalic acid, heat and stir at 100℃ for 7h to obtain a mixture containing lithium and cobalt. At this time, cobalt will leach into the solvent, and lithium will precipitate in the form of oxalate.

[0085] (3) The mixture obtained in step (2) was filtered to obtain a leachate and lithium oxalate precipitate. The lithium element was analyzed using an ICP-OES instrument (ICAP6300, USA), and the lithium element recovery rate was calculated to be 93%. The obtained leachate was then used for the next step.

[0086] (4) Add 50 mL of water to the leachate obtained in step (3), filter, and obtain cobalt oxalate dihydrate precipitate and leachate aqueous solution. Dry the precipitate to obtain cobalt oxalate dihydrate solid. Analyze the cobalt element in the precipitate using an ICP-OES instrument, and the cobalt element recovery rate is calculated to be 91%.

[0087] (5) Collect the leachate aqueous solution from step (4), evaporate the water, and obtain the regenerated leachate.

[0088] Example 9

[0089] A method for selectively recycling lithium and cobalt from waste lithium-ion battery cathode materials, such as Figure 1 As shown, it includes the following steps:

[0090] (1) Mix 33.19g of chloroacetic acid with 30.57g of tetrabutylammonium chloride (3:1 molar ratio), heat to 70°C, and stir to form an leaching solvent.

[0091] (2) Weigh 0.8g of waste lithium-ion battery cathode material lithium cobalt oxide powder (mass content of each element: Co: 60.21wt%; Li: 6.94wt%), add it to 50mL of the leaching solvent obtained in step (1), then add 1.8g of oxalic acid, heat and stir at 100℃ for 7h to obtain a mixture containing lithium and cobalt. At this time, cobalt will leach into the solvent, and lithium will precipitate in the form of oxalate.

[0092] (3) The mixture obtained in step (2) was filtered to obtain a leachate and lithium oxalate precipitate. The lithium element was analyzed using an ICP-OES instrument (ICAP6300, USA), and the lithium element recovery rate was calculated to be 98%. The obtained leachate was then used for the next step.

[0093] (4) Add 50 mL of water to the leachate obtained in step (3), filter, and obtain cobalt oxalate dihydrate precipitate and leachate aqueous solution. Dry the precipitate to obtain cobalt oxalate dihydrate solid. Analyze the cobalt element in the precipitate using an ICP-OES instrument, and the cobalt element recovery rate is calculated to be 89%.

[0094] (5) Collect the leachate aqueous solution from step (4), evaporate the water, and obtain the regenerated leachate.

[0095] Example 10

[0096] A method for selectively recycling lithium and cobalt from waste lithium-ion battery cathode materials, such as Figure 1 As shown, it includes the following steps:

[0097] (1) Mix 33.19g of chloroacetic acid with 30.57g of tetrabutylammonium chloride (3:1 molar ratio), heat to 70°C, and stir to form an leaching solvent.

[0098] (2) Weigh 0.8g of waste lithium-ion battery cathode material lithium cobalt oxide powder (mass content of each element: Co: 60.21wt%; Li: 6.94wt%), add it to 50mL of the leaching solvent obtained in step (1), then add 1.6g of oxalic acid, heat and stir at 100℃ for 7h to obtain a mixture containing lithium and cobalt. At this time, cobalt will leach into the solvent, and lithium will precipitate in the form of oxalate.

[0099] (3) The mixture obtained in step (2) was filtered to obtain a leachate and lithium oxalate precipitate. The lithium element was analyzed using an ICP-OES instrument (ICAP6300, USA), and the lithium element recovery rate was calculated to be 98%. The obtained leachate was then used for the next step.

[0100] (4) Add 40 mL of water to the leachate obtained in step (3), filter, and obtain cobalt oxalate dihydrate precipitate and leachate aqueous solution. Dry the precipitate to obtain cobalt oxalate dihydrate solid. Analyze the cobalt element in the precipitate using an ICP-OES instrument, and the cobalt element recovery rate is calculated to be 88%.

[0101] (5) Collect the leachate aqueous solution from step (4), evaporate the water, and obtain the regenerated leachate.

[0102] Comparative Example 1

[0103] The difference from Example 1 is that the molar ratio of chloroacetic acid to tetrabutylammonium chloride is 4:1, and steps (2) to (4) are not repeated after step (4). Analysis of the obtained lithium and cobalt elements showed that the recovery rates of lithium and cobalt were both 86%. It is evident that as the proportion of chloroacetic acid increases, the recovery rates of both metals decrease simultaneously.

[0104] Comparative Example 2

[0105] The difference from Example 1 is that the molar ratio of chloroacetic acid to tetrabutylammonium chloride is 2.5:1, and steps (2) to (4) are not repeated after step (4). During this process, the stirring resistance is high, and the lithium and cobalt elements obtained are analyzed. The calculated recovery rate of lithium is 90%, and the recovery rate of cobalt is 88%. It can be seen that after the proportion of chloroacetic acid decreases, the viscosity increases, the acidity of the solvent decreases, the metal solubility decreases, and the recovery rate of both metals also decreases simultaneously.

[0106] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for selectively recovering lithium and cobalt from waste lithium cathode material lithium cobaltate, characterized in that, The method comprises the following steps: S1: proportionally weigh chloroacetic acid and tetrabutylammonium chloride, mix them, heat and stir to form a leaching solvent; S2: add waste lithium cobaltate powder to the prepared leaching solvent, add a certain amount of oxalic acid, heat and stir at 90-100℃, so that cobalt in the lithium cobaltate selectively dissolves in the leaching solvent, and lithium reacts with oxalic acid to form lithium oxalate precipitate which is insoluble in the leaching solvent at 90-100℃; S3: filter the mixture produced in S2 to obtain a leaching solution containing cobalt and lithium oxalate solid precipitate; S4: add water to the leaching solution containing cobalt obtained in S3, and after filtration, obtain cobalt oxalate dihydrate solid precipitate and leaching solution aqueous solution; S5: evaporate the water in the leaching solution aqueous solution to obtain regenerated leaching solvent which can be repeatedly used for leaching lithium battery cathode material; In step S2, the solid-liquid ratio of the waste lithium cobaltate powder to the leaching solvent is 10-20 g / L, and the amount of oxalic acid added is 20-40 g / L.

2. The method of claim 1, wherein, In step S1, the molar ratio of chloroacetic acid to tetrabutylammonium chloride is 2.8:1-3.2:

1.

3. The method of claim 1, wherein, In step S1, the heating temperature for forming the leaching solvent is 65-75℃.

4. The method of claim 1, wherein, In step S2, the stirring time is 5-7 h.

5. The method of claim 1, wherein, In step S4, the amount of water added is equal in volume to the leaching solution.

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