Electrochemical system for recycling positive electrode active material of waste battery and recycling method of positive electrode active material of waste battery

Abstract

The invention provides an electrochemical system for recycling a waste battery positive electrode active material and a recycling method of the waste battery positive electrode active material, and relates to the field of waste battery recycling. The electrochemical system comprises a positive electrode material pretreatment device and a metal ion separation device; the metal ion separation device comprises a Co < 2 + > electrolytic separation device and a Li < + > enrichment device, the Co < 2 + > electrolytic separation device is communicated with the Li < + > enrichment device through a salt bridge, and the Co < 2 + > electrolytic separation device is communicated with a liquid outlet of the positive electrode material pretreatment device; and the cathode of the Co < 2 + > electrolytic separation device comprises an MOF-303 modified titanium electrode. According to the method, the metal ions in the layered oxide positive electrode material of the lithium ion battery can be efficiently recycled in an environment-friendly manner, the separation purity can be effectively improved, the process is simplified, the energy consumption is reduced, and the problems of low separation purity, complex process and high energy consumption of the layered oxide metal ions of the lithium ion battery in the prior art are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of waste battery recycling, and in particular to an electrochemical system for recycling positive active material of waste batteries and a recycling method of positive active material of waste batteries. BACKGROUND

[0002] With the rapid development of lithium-ion battery industry, recycling and utilization of metal resources in waste batteries has become an important issue. At present, the mainstream recycling technologies mainly include hydrometallurgy, pyrometallurgy and traditional electrochemical method. Hydrometallurgy relies on acid leaching and chemical precipitation to realize separation of metal ions, but has problems such as large reagent consumption, easy secondary pollution, and complex process flow, usually requiring 5-8 steps, and the processing period is as long as 12-24 hours. Pyrometallurgy has a simple process, but needs to be carried out at high temperature (>800℃), has high energy consumption (about 5 kWh / kg metal), and is easy to cause metal volatilization loss, and the overall recovery rate is generally lower than 85%.

[0003] The traditional electrochemical method separates based on the difference in reduction potential of metal ions. However, the potential difference between Ni 2+ (-0.25 V vs. SHE) and Co 2+ (-0.28 V vs. SHE) is only 0.03 V, and it is difficult to achieve efficient separation, and the actual separation purity is usually lower than 95%. Therefore, it is an urgent need in the industry to develop a metal ion separation technology with low energy consumption, high selectivity and simple process. SUMMARY

[0004] The present application aims to provide an electrochemical system for recycling positive active material of waste batteries and a recycling method of positive active material of waste batteries to solve the above problems.

[0005] To achieve the above purpose, the following technical solutions are adopted in the present application: The present application provides an electrochemical system for recycling positive active material of waste batteries, comprising: a positive material pretreatment device, a metal ion separation device; The positive material pretreatment device is used for dissolving metal ions in the positive active material of waste batteries; The metal ion separation device comprises a Co 2+ electrolytic separation device and a Li + enrichment device, the Co 2+ electrolytic separation device and the Li + enrichment device are communicated through a salt bridge, and the Co 2+ electrolytic separation device is communicated with the liquid outlet of the positive material pretreatment device; The Co 2+The cathode of the electrolytic separation device comprises a MOF-303 modified titanium electrode.

[0006] According to an embodiment of the present application, the preparation method of the MOF-303 modified titanium electrode comprises: The titanium electrode is pretreated to remove the surface oxide layer of the titanium electrode, thereby obtaining a pretreated titanium electrode; MOF-303, 3-aminopropyltriethoxysilane and an alcohol solvent are mixed and reacted at a temperature of 25-35 DEG C for 1.9-2.1 hours to obtain a modified liquid, wherein the mass ratio of the MOF-303 to the 3-aminopropyltriethoxysilane is 8-12:1; A three-electrode system is constructed with the pretreated titanium electrode as a working electrode, a platinum sheet as a counter electrode and a saturated calomel electrode as a reference electrode; the electrodes are immersed in the modified liquid, the distance between the electrodes is fixed at 1.8-2.2 cm, a direct current voltage of 1.4-1.6 V is applied, and the MOF-303 modified titanium electrode is obtained by depositing for 9-11 minutes.

[0007] According to an embodiment of the present application, the metal ion separation device further comprises a Ni 2+ The electrolytic separation device, Mn 2+ The electrolytic separation device, Co 2+ The electrolytic separation device and the Ni 2+ The electrolytic separation device is connected through a salt bridge, and the Ni 2+ The electrolytic separation device and the Mn 2+ The electrolytic separation device is connected through a salt bridge, and the Mn 2+ The electrolytic separation device and the Li + The enrichment device is connected through a salt bridge.

[0008] According to an embodiment of the present application, the Ni 2+ The cathode of the electrolytic separation device comprises a UiO-66-NH2 modified electrode; The preparation method of the UiO-66-NH2 modified electrode comprises: A stainless steel electrode is fixed on a sample table by using a hot-wall atomic layer deposition system, ZrCl4 is used as a zirconium source, 2-amino terephthalic acid is used as an organic ligand source, and water is used as an oxygen source; a deposition temperature is set to 110-135 DEG C, a carrier gas flow is 18-22 sccm, and the carrier gas is nitrogen; a single deposition cycle includes: ZrCl4 pulse 0.4-0.6 s, nitrogen blowing 9.5-10.5 s, 2-amino terephthalic acid pulse 0.9-1.1 s, nitrogen blowing 14-16 s, water pulse 0.19-0.21 s, nitrogen blowing 9.9-10.1 s, a total of 48-52 cycles, after deposition, the temperature is kept in a vacuum oven at 90-110 DEG C for 0.9-1.1 hours, and the temperature is naturally cooled to room temperature, thereby obtaining a UiO-66-NH2 modified electrode.

[0009] According to the embodiments of the present application, the Mn 2+ The anode of the electrolytic separation device comprises the PSP-UiO-66 modified electrode; The preparation method of the PSP-UiO-66 modified electrode comprises: UiO-66 powder, DMF and PSP are mixed, and reacted at a temperature of 50-70 DEG C for 23-25 hours; after the reaction is completed, washing and drying are performed, thereby obtaining a PSP-UiO-66 composite material, wherein the mass ratio of the UiO-66 to the PSP is 6-10:1; The PSP-UiO-66 composite material is mixed with ethanol according to a solid-liquid ratio of 0.1-0.3 g / 50 mL to form a dispersion liquid; a graphite electrode is used as a working electrode, a platinum sheet is used as a counter electrode, a saturated calomel electrode is used as a reference electrode, the electrode spacing is 1.8-2.2 cm, a direct current voltage of 1.4-1.6 V is applied, and the electrode is deposited for 11-13 minutes; after deposition, the electrode is washed and dried, thereby obtaining a PSP-UiO-66 modified electrode.

[0010] According to the embodiments of the present application, the Li + The enrichment device comprises a cathode chamber and an anode chamber, an ion exchange membrane is arranged between the cathode chamber and the anode chamber, and the material forming the ion exchange membrane comprises PSP-UiO-66; The preparation method of the ion exchange membrane comprises: The PSP-UiO-66 composite material, PVDF and DMF are mixed under light-proof conditions to obtain a casting solution, wherein the mass of the PSP-UiO-66 composite material accounts for 2%-3% of the mass of the PVDF; The casting solution is coated on a substrate by using a flow casting method, and the coating gap is controlled to be 100-150 mu m; The coated substrate is preformed at a temperature of 59-61 DEG C under light-proof conditions for 5.9-6.1 hours, thereby obtaining a preformed film; The preformed film is vacuum dried at 95-105°C for 11-13 hours to remove the solvent, thereby obtaining the formed film. After cooling, the molded membrane is peeled off from the substrate to obtain an ion exchange membrane with a thickness of 80-120 μm; The metal ion separation device also includes multiple conveying pipes, each of which is equipped with an electric pump. The multiple conveying pipes are respectively located at the Co... 2+ Electrolytic separation device and the Ni 2+ Between the electrolytic separation devices, the Ni 2+ Electrolytic separation device and the Mn 2+ Between the electrolytic separation devices, the Mn 2+ Electrolytic separation device and the Li + Between enrichment devices.

[0011] This application also provides a method for recycling positive electrode active materials from spent batteries, employing the electrochemical system described above for recycling positive electrode active materials from spent batteries, wherein the positive electrode active material from spent batteries is a layered oxide, and the recycling method includes: The positive electrode active material of the waste battery is mixed with an acidic solution in a positive electrode material pretreatment device to carry out a leaching reaction and obtain a metal leaching solution. The metal leaching solution is transported to Co 2+ In the electrolytic separation device, a pulsed voltage is applied to initiate the first electrolytic reaction, causing Co to... 2+ Deposition; Will pass through Co 2+ The solution processed by the electrolytic separation unit is transported to Li + In the enrichment device, Li + Enrichment.

[0012] According to embodiments of this application, the layered oxide includes LiCoO2 and LiNi. x Co y Mn z At least one of O2, wherein, 0 <x<1,0<y<1,0<z<1,x+y+z=1; The parameters of the first electrolysis reaction include: cathode potential of -0.28~-0.30V vs SHE, pulse voltage frequency of 0.8-1.2Hz, pulse voltage duty cycle of 58-62%, and first electrolysis reaction time of 1.5-2 hours.

[0013] According to embodiments of this application, after the first electrolysis reaction, the method further includes: reacting the electrolyte with Co... 2+ The solution processed by the electrolytic separation unit is transported to Ni 2+ In the electrolytic separation unit, a second electrolytic reaction takes place, causing Ni to...2+ Deposition; Will pass through Ni 2+ The solution processed by the electrolytic separation unit is transported to Mn 2+ In the electrolytic separation device, under ultraviolet light irradiation, the third electrolytic reaction is carried out, causing Mn to... 2+ Deposition.

[0014] According to an embodiment of this application, the parameters of the second electrolysis reaction include: a cathode potential of -0.25 to -0.27 V vs SHE, and a reaction time of 1.9 to 2.1 hours; The parameters for the third electrolysis reaction include: anodic potential ≥ 1.23V vs SHE, ultraviolet light power of 290-310W, irradiation distance from the light source to the anode surface of 10-15cm, and ultraviolet light intensity of 100-150mW / cm². 2 The time for the third electrolysis reaction is 1.4-1.6 hours.

[0015] Compared with the prior art, the beneficial effects of this application include: This application provides a method for efficiently and environmentally recovering metal ions (Li) from layered oxide cathode materials used in lithium-ion batteries. + Ni 2+ Co 2+ Mn 2+ The electrochemical separation method and system for lithium-ion batteries can effectively improve separation purity, simplify the process, and reduce energy consumption, thus improving the existing technology for separating lithium-ion battery layered oxide metal ions (Li... + Ni 2+ Co 2+ Mn 2+ The problem of low purity separation, complex process and high energy consumption.

[0016] Specifically, this application can expand the separation window of metal ions and improve the Ni / Co separation factor. Moreover, this application can simultaneously separate multiple metal ions, reducing processing steps compared to traditional processes. Furthermore, the MOF-modified electrode used in this application can be recycled more than 50 times, with an activity retention rate exceeding 90%, significantly reducing operating costs. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0018] Figure 1 This is a schematic diagram of the electrochemical system for recycling positive electrode active materials from waste batteries, as described in this application.

[0019] Explanation of reference numerals in the attached figures 100-Metal ion separation device, 110-Co 2+ Electrolytic separation device, 111-Co 2+ Cathode of the electrolytic separation device, 112-Co 2+ The anode of the electrolytic separation device, 120-Li + Enrichment device, 121-cathode chamber, 122-anode chamber, 123-ion exchange membrane, 130-Ni 2+ Electrolytic separation device, 131-Ni 2+ Cathode of the electrolytic separation device, 132-Ni 2+ The anode of the electrolytic separation unit, 140-Mn 2+ Electrolytic separation device, 141-Mn 2+ The anode of the electrolytic separation unit, 142-Mn 2+ Cathode of the electrolytic separation device, 150-salt bridge, 160-transfer pipeline, 161-electric pump, 170-voltage control module. Detailed Implementation

[0020] As used in this article: "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.

[0021] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0022] 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.

[0023] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0024] "Parts by mass" refers to the basic unit of measurement that expresses the mass ratio of multiple components. One part can represent any unit mass, such as 1g or 2.689g. If we say that component A has "a" parts by mass and component B has "b" parts by mass, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it can mean that the mass of component A is aK and the mass of component B is bK (where K is any number representing a multiplier). It is important to understand that, unlike parts by mass, the sum of the mass parts of all components is not limited to 100 parts.

[0025] "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).

[0026] This application provides an electrochemical system for recycling positive electrode active materials from waste batteries, including: a positive electrode material pretreatment device and a metal ion separation device 100; The cathode material pretreatment device is used to dissolve metal ions from the cathode active material of waste batteries; Metal ion separation device 100 includes Co 2+ Electrolytic separation device 110 and Li + Enrichment device 120, Co 2+ Electrolytic separation device 110 and Li + Enrichment device 120 is connected via salt bridge 150, Co 2+ The electrolytic separation device 110 is connected to the liquid outlet of the positive electrode material pretreatment device; Co 2+ The cathode 111 of the electrolytic separation device includes a MOF-303 modified titanium electrode, Co 2+ The anode 112 of the electrolytic separation device is a platinum sheet.

[0027] According to embodiments of this application, the preparation method of the MOF-303 modified titanium electrode includes: The titanium electrode is pretreated to remove the surface oxide layer, resulting in a pretreated titanium electrode. MOF-303, 3-aminopropyltriethoxysilane, and an alcohol solvent are mixed and reacted at a temperature of 25-35°C (e.g., 25°C, 28°C, 30°C, 32°C, 35°C, or any value between 25-35°C) for 1.9-2.1 hours (e.g., 1.9 hours, 2 hours, 2.1 hours, or any value between 1.9-2.1 hours) to obtain a modified solution, wherein the mass ratio of MOF-303 to 3-aminopropyltriethoxysilane is 8-12:1 (e.g., 8:1, 10:1, 12:1, or any value between 8-12:1). A three-electrode system was constructed using a pretreated titanium electrode as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. The electrodes were immersed in a modification solution with a fixed electrode spacing of 1.8-2.2 cm (e.g., 1.8 cm, 2 cm, 2.2 cm, or any value between 1.8-2.2 cm). A DC voltage of 1.4-1.6 V (e.g., 1.4 V, 1.5 V, 1.6 V, or any value between 1.4-1.6 V) was applied, and deposition was carried out for 9-11 minutes (e.g., 9 minutes, 10 minutes, 11 minutes, or any value between 9 and 11 minutes) to obtain a MOF-303 modified titanium electrode.

[0028] According to an embodiment of this application, the metal ion separation device 100 further includes Ni 2+ Electrolytic separation device 130, Mn 2+ Electrolytic separation unit 140, Co 2+ Electrolytic separation device 110 and Ni 2+ Electrolytic separation device 130 is connected via salt bridge 150, Ni 2+ Electrolytic separation device 130 and Mn 2+ Electrolytic separation device 140 is connected via salt bridge 150, Mn 2+ Electrolytic separation device 140 and Li + The enrichment device 120 is connected via a salt bridge 150.

[0029] In some embodiments, the salt bridge uses deionized water as a solvent, 1-3% (preferably 2%) potassium chloride (KCl) as an electrolyte, 1.5-2.5% (preferably 2%) agarose as a gel matrix, and also incorporates a perfluorosulfonic acid type cation exchange membrane (such as Nafion 117, with a thickness of 200-250 μm and an ion exchange capacity of 1.0-1.2 meq / g), forming a composite system of "gel + electrolyte + selective membrane". The salt bridge has a tubular, layered structure, with a total length of 10-15 cm and an inner diameter of 8-12 mm. It consists of three layers from the outside in: Outer layer (support shell): made of borosilicate glass or polytetrafluoroethylene (PTFE) tubing, 1-2 mm thick, with fluororubber sealing rings at both ends for support and sealing to prevent electrolyte leakage; Middle layer (gel electrolyte layer): filling the space between the outer and inner layers, 3-5 mm thick, a porous gel (50-100 nm pore diameter) formed by agarose and KCl, used to immobilize the electrolyte, conduct ions, and buffer pH differences between tanks; Inner layer (selective separation channel): the central channel (2-4 mm inner diameter) running through the salt bridge, with a perfluorosulfonic acid cation exchange membrane (tubular, 0.2-0.25 mm thick) attached to its inner wall. Both ends of the membrane are covered with 50-100 mesh PTFE filters, allowing only Li+ to pass through. + By blocking divalent transition metal ions.

[0030] According to embodiments of this application, Ni 2+ The cathode 131 of the electrolytic separation device includes a UiO-66-NH2 modified electrode, Ni 2+ The anode 132 of the electrolytic separation device is a platinum sheet; The preparation methods of UiO-66-NH2 modified electrodes include: A hot-wall atomic layer deposition system was used, with ZrCl4 as the zirconium source, 2-aminoterephthalic acid as the organic ligand source, and water as the oxygen source. A stainless steel electrode was fixed to the sample stage, and the deposition temperature was set to 110-135℃ (e.g., 110℃, 120℃, 130℃, 135℃, or any value between 110-135℃), with a carrier gas flow rate of 18-22 sccm (e.g., 18 sccm, 20 sccm, 22 sccm, or 18-22 sccm). The carrier gas is nitrogen, and the total deposition cycle consists of: a ZrCl4 pulse of 0.4–0.6 s (e.g., 0.4 s, 0.5 s, 0.6 s, or any value between 0.4 and 0.6 s), a nitrogen purging of 9.5–10.5 s (e.g., 9.5 s, 10 s, 10.5 s, or any value between 9.5 and 10.5 s), a 2-aminoterephthalic acid pulse of 0.9–1.1 s (e.g., 0.9 s, 1 s, 1.1 s, or any value between 0.9 and 1.1 s), a nitrogen purging of 14–16 s (e.g., 14 s, 15 s, 16 s, or any value between 14 and 16 s), and a water pulse of 0.19–0.21 s (e.g., 0.19 s, 0.21 s). The deposition process involves purging with nitrogen for 9.9-10.1 s (e.g., 9.9 s, 10 s, 10.1 s, or any value between 9.9 and 10.1 s) for a total of 48-52 cycles (e.g., 48, 50, 52, or any value between 48 and 52). After deposition, the electrode is kept at 90-110℃ (e.g., 90℃, 100℃, 110℃, or any value between 90 and 110℃) in a vacuum oven for 0.9-1.1 hours (e.g., 0.9 hours, 1 hour, 1.1 hours, or any value between 0.9 and 1.1 hours) and then naturally cooled to room temperature to obtain the UiO-66-NH2 modified electrode.

[0031] According to an embodiment of this application, Mn 2+ The anode 141 of the electrolytic separation device includes a PSP-UiO-66 modified electrode, Mn 2 + The cathode 142 of the electrolytic separation device includes a graphite electrode; The preparation methods of PSP-UiO-66 modified electrodes include: UiO-66 powder, DMF, and PSP are mixed and reacted at a temperature of 50-70℃ (e.g., 50℃, 60℃, 70℃, or any value between 50-70℃) for 23-25 ​​hours (e.g., 23 hours, 24 hours, 25 hours, or any value between 23-25 ​​hours). After the reaction is complete, the mixture is washed and dried to obtain a PSP-UiO-66 composite material, wherein the mass ratio of UiO-66 to PSP is 6-10:1 (e.g., 6:1, 8:1, 10:1, or any value between 6-10:1). The PSP-UiO-66 composite material was mixed with ethanol at a solid-liquid ratio of 0.1-0.3 g / 50 mL (e.g., 0.1 g / 50 mL, 0.2 g / 50 mL, 0.3 g / 50 mL, or any value between 0.1-0.3 g / 50 mL) to form a dispersion. A graphite electrode was used as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. The electrode spacing was 1.8-2.2 cm (e.g., 1.8 cm, 2 cm, 2.2 cm, or any value between 1.8-2.2 cm). A DC voltage of 1.4-1.6 V (e.g., 1.4 V, 1.5 V, 1.6 V, or any value between 1.4-1.6 V) was applied for deposition for 11-13 minutes (e.g., 11 minutes, 12 minutes, 13 minutes, or any value between 11-13 minutes). The deposited electrode was washed and dried to obtain the PSP-UiO-66 modified electrode.

[0032] The PSP-UiO-66 modified electrode of this application is a photosensitive material. By using ultraviolet light irradiation, the pore size (6.0±0.5Å) and adsorption performance of the PSP-UiO-66 modified electrode can be dynamically adjusted to achieve precise control of the separation process.

[0033] According to embodiments of this application, Li + The enrichment device 120 includes a cathode chamber 121 and an anode chamber 122. An ion exchange membrane 123 is provided between the cathode chamber 121 and the anode chamber 122. The material forming the ion exchange membrane 123 includes PSP-UiO-66. Methods for preparing ion exchange membranes include: PSP-UiO-66 composite material, PVDF (polyvinylidene fluoride) and DMF are mixed under light-protected conditions to obtain a casting solution, wherein the mass of PSP-UiO-66 composite material accounts for 2%-3% of the mass of PVDF (e.g., 2%, 2.5%, 3% or any value between 2% and 3%). The casting solution is coated onto the substrate using a casting method, and the casting gap is controlled to be 100-150μm (e.g., 100μm, 120μm, 125μm, 140μm, 150μm or any value between 100-150μm). The coated substrate is pre-formed in the dark at a temperature of 59-61°C (e.g., 59°C, 60°C, 61°C or any value between 59-61°C) for 5.9-6.1 hours (e.g., 5.9 hours, 6 hours, 6.1 hours or any value between 5.9-6.1 hours) to obtain a pre-formed film. The preformed film is vacuum dried at a temperature of 95-105°C (e.g., 95°C, 100°C, 105°C or any value between 95-105°C) for 11-13 hours (e.g., 11 hours, 12 hours, 13 hours or any value between 11-13 hours) to remove the solvent, thereby obtaining the formed film. After cooling, the molded membrane is peeled off from the substrate to obtain an ion exchange membrane with a thickness of 80-120 μm (e.g., 80 μm, 100 μm, 120 μm or any value between 80-120 μm). The metal ion separation device also includes multiple conveying pipes 160, each of which is equipped with an electric pump 161. The multiple conveying pipes 160 are respectively located in Co 2+ Electrolytic separation device 110 and Ni 2+ Between electrolytic separation unit 130, Ni 2+ Electrolytic separation device 130 and Mn 2+ Between electrolytic separation unit 140, Mn 2+ Electrolytic separation device 140 and Li + Enrichment device 120.

[0034] The electrochemical system for recycling positive electrode active materials from waste batteries in this application may further include multiple voltage regulation modules 170, wherein the multiple voltage regulation modules 170 are respectively located in Co 2+ Electrolytic separation device 110, Ni 2+ Electrolytic separation device 130, Mn 2+ Electrolytic separation device 140, Li + In the enrichment device 120, the operating voltage of each electrolysis unit is set and maintained stably.

[0035] Furthermore, the electrochemical system for recycling positive electrode active materials from waste batteries may also include a central control system and multiple in-situ monitoring sensors, with the multiple in-situ monitoring sensors located at Co... 2+ Electrolytic separation device 110 and Ni 2+ Electrolytic separation device 130, Mn 2+ Electrolytic separation device 140, Li +In the enrichment device 120, information such as concentration and pH in the solution is monitored in real time. This application can also adjust process parameters in real time based on in-situ monitoring data, further reducing energy consumption. Specifically, the central control system can automatically adjust the voltage (±0.01V accuracy) and light intensity (100-150mW / cm²) based on in-situ monitoring data. 2 The electrolyte circulation rate (30-70 mL / min) is controlled in a closed loop.

[0036] This application also provides a method for recycling positive electrode active materials from spent batteries, employing the electrochemical system described above for recycling positive electrode active materials from spent batteries. The positive electrode active material from spent batteries is a layered oxide. The recycling method includes: The positive electrode active material of the waste battery is mixed with an acidic solution in a positive electrode material pretreatment device to carry out a leaching reaction and obtain a metal leaching solution. The metal leaching solution is transported to Co 2+ In the electrolytic separation device, a pulsed voltage is applied to initiate the first electrolytic reaction, causing Co to... 2+ Deposition; Will pass through Co 2+ The solution processed by the electrolytic separation unit is transported to Li + In the enrichment device, Li + Enrichment.

[0037] In some embodiments, the preparation of the metal leaching solution includes: pulverizing the layered oxide, adding 0.5-2 mol / L H2SO4 solution and 3%-8% H2O2 as a reducing agent, stirring the reaction at 50-70°C for 1-3 hours, filtering to remove residue, and obtaining the metal leaching solution.

[0038] In some embodiments, the content ratio of layered oxide to H2SO4 solution is 1:15-20 g / mL, and the mass ratio of H2O2 to layered oxide is 0.07-0.4:1.

[0039] In some embodiments, Li in the metal leaching solution + The concentration is 0.5-1.0 g / L, Ni 2+ The concentration was 2.0-3.0 g / L, Co 2+ The concentration is 1.0-1.5 g / L, Mn 2+ The concentration is 0.8-1.2 g / L.

[0040] According to embodiments of this application, the layered oxides include LiCoO2 and LiNi. x Co y Mn z At least one of O2, wherein, 0 <x<1,0<y<1,0<z<1,x+y+z=1; In some embodiments, x is 0.5, y is 0.2, z is 0.3, and LiNi x Co y Mn z O2 is LiNi 0.5 Co 0.2 Mn 0.3 O2.

[0041] The parameters for the first electrolysis reaction include: a cathode potential of -0.28 to -0.30V vs SHE (e.g., -0.28V, -0.29V, -0.30V, or any value between -0.28 and -0.30V), a pulse voltage frequency of 0.8-1.2Hz (e.g., 0.8Hz, 1Hz, 1.2Hz, or any value between 0.8 and 1.2Hz), a pulse voltage duty cycle of 58-62% (e.g., 58%, 60%, 62%, or any value between 58 and 62%), and a first electrolysis reaction time of 1.5-2 hours (e.g., 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, 2 hours, or any value between 1.5 and 2 hours).

[0042] Under the above conditions, Co can be made 2+ Selective adsorption and reduction deposition result in a separation purity ≥99.2%. Specifically, the MOF-303-modified titanium electrode can selectively adsorb Co. 2+ , making Co 2+ Electrodeposition of Co at the cathode. MOF-303-modified titanium electrode. 2+ The adsorption binding energy (-4.2 eV) is much higher than that for Ni. 2+ With an adsorption binding energy of -3.1 eV, it will preferentially adsorb Co from the solution. 2+ Under the aforementioned cathode potential, the adsorbed Co 2+ Electron-gain reduction deposition: Co 2+ + 2e - → Co↓. At this time, Li + Mn 2+ The titanium electrode, which is not adsorbed by the MOF-303 modified titanium electrode and exhibits no reduction reaction, enters the next stage separation unit with the solution; the MOF-303 modified titanium electrode is effective against Ni. 2+ The adsorption effect of Ni is weak. 2+ It also migrates with the solution into the next stage of separation.

[0043] According to embodiments of this application, after the first electrolysis reaction, the method further includes: reacting the electrolyte with Co... 2+ The solution processed by the electrolytic separation unit is transported to Ni 2+ In the electrolytic separation unit, a second electrolytic reaction takes place, causing Ni to... 2+ Deposition; Will pass through Ni 2+ The solution processed by the electrolytic separation unit is transported to Mn 2+ In the electrolytic separation device, under ultraviolet light irradiation, the third electrolytic reaction is carried out, causing Mn to... 2+ Deposition.

[0044] According to an embodiment of this application, the parameters of the second electrolysis reaction include: a cathode potential of -0.25 to -0.27V vsSHE (e.g., -0.25V, -0.26V, -0.27V, or any value between -0.25V and -0.27V), and a second electrolysis reaction time of 1.9 to 2.1 hours (e.g., 1.9 hours, 2 hours, 2.1 hours, or any value between 1.9 and 2.1 hours). Electrolyte enters Ni 2+ In the electrolytic separation apparatus, the UiO-66-NH2 modified electrode is used as the cathode. At a potential of -0.25 to -0.27 V vsSHE, Ni... 2+ The separation purity is ≥99.2% achieved through amino-site specific adsorption and deposition. Specifically, the amino groups (-NH2) on the surface of UiO-66-NH2 react with Ni... 2+ Stable coordination bonds are formed (Ni-N bond energy 385 kJ / mol), achieving selective adsorption; at a cathode potential of -0.25 to -0.27 V vs SHE, the coordinated Ni... 2+ Electron-gain reduction deposition: Ni 2+ + 2e - → Ni↓. At this time, Co 2 + Complete separation was achieved in the previous stage (residual ≤0.01g / L), Li + Mn 2+ No reaction occurs; it enters the Mn solution. 2+ Electrolytic separation device.

[0045] The parameters for the third electrolysis reaction include: an anode potential ≥1.23V vs SHE (e.g., 1.23V, 1.24V, 1.25V, 1.26V, 1.27V, or any value ≥1.23V), an ultraviolet light power of 290-310W (e.g., 290W, 300W, 310W, or any value between 290-310W), an irradiation distance from the light source to the anode surface of 10-15cm (e.g., 10cm, 11cm, 12cm, 13cm, 14cm, 15cm, or any value between 10-15cm), and an ultraviolet light intensity of 100-150mW / cm². 2 (e.g., 100mW / cm) 2 110mW / cm 2 120mW / cm 2130mW / cm 2 140mW / cm 2 150mW / cm 2 Or 100-150mW / cm 2 The time for the third electrolysis reaction is 1.4-1.6 hours (e.g., 1.4 hours, 1.5 hours, 1.6 hours, or any value between 1.4 and 1.6 hours).

[0046] In Mn 2+ In the electrolytic separation device, the PSP-UiO-66 modified electrode is used as the anode. Under an anode potential of ≥1.23V vs SHE and ultraviolet light irradiation, Mn 2+ Oxidation to MnO2, with a separation purity ≥99.0%. Specifically, under ultraviolet light irradiation, PSP (polyspiropyran) isomerization expands the MOF pore size from 5 Å to 7 Å, facilitating the separation of MnO2. 2+ Contact anode; at an anode potential ≥1.23V vs SHE, Mn 2+ Mn loses electrons and oxidizes to form MnO2 precipitate: Mn 2+ + 2H₂O - 2e - → MnO2↓ + 4H + At this time, Li + It does not participate in the oxidation reaction, but migrates to the electrodialysis unit through the cation exchange membrane of the salt bridge, and is eventually enriched in electrodialysis (the concentration increases from 0.8 g / L to 3.5 g / L).

[0047] It should be noted that the separation purity in this application refers to the purity of the target product (such as Co) after a certain stage of separation. 2+ Co deposition layer and Ni in electrolytic separation unit 2+ Ni deposition layer and Mn in electrolytic separation unit 2+ MnO2 in the electrolytic separation unit, Li in electrodialysis + In a solution, the percentage of the target metal element's mass relative to the total mass of metal elements is considered a high-efficiency separation if the separation purity is ≥99%. The testing method employs inductively coupled plasma optical emission spectrometry (ICP-OES): after atomizing the product (dissolved deposit or solution), the concentration of each metal ion is quantitatively analyzed by spectral intensity to calculate the percentage of the target metal.

[0048] Activity retention rate refers to the ratio (expressed as a percentage) of the core separation activity (such as adsorption capacity for target ions, electrodeposition efficiency, etc.) of a MOF-modified electrode after multiple cycles of use to the initial activity at the time of first use.

[0049] The Co / Ni separation factor refers to the ratio of the relative enrichment of Co in the cathodic deposit to the relative enrichment of Ni in the cathodic deposit. Specifically, the relative enrichment of Co is the ratio of the mass fraction of Co in the deposit to the mass fraction of Co in the original metal leaching solution, and the relative enrichment of Ni is the ratio of the mass fraction of Ni in the deposit to the mass fraction of Ni in the original metal leaching solution.

[0050] The implementation schemes of this application 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 this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0051] 1. Preparation of MOF-303 modified titanium electrode. The preparation method of MOF-303 modified titanium electrode includes the following steps: (1) Substrate pretreatment: The titanium electrode (size 10mm×20mm×0.5mm) was polished to a mirror finish by cross-polishing with 800# and 1200# silicon carbide sandpaper. After rinsing with deionized water, it was immersed in 5% (mass fraction) dilute hydrochloric acid solution and ultrasonically treated for 15 minutes (power 300W) to remove the surface oxide layer. After taking it out, it was rinsed with deionized water until neutral, and then ultrasonically cleaned with anhydrous ethanol for 10 minutes. It was then vacuum dried at 60℃ for later use.

[0052] (2) Preparation of MOF modified solution: Weigh 0.5g MOF-303 powder, add 50mL of anhydrous ethanol, stir magnetically (500r / min) and sonicate at 300W for 30 minutes to form a uniform dispersion; add 3-aminopropyltriethoxysilane to the dispersion, wherein the mass ratio of MOF-303 to 3-aminopropyltriethoxysilane is 10:1 (i.e. 0.05g 3-aminopropyltriethoxysilane), stir in a constant temperature water bath at 30℃ for 2 hours (300r / min) to complete the amino functionalization modification of MOF surface.

[0053] (3) Electrophoretic deposition: A three-electrode system was constructed using a pretreated titanium electrode as the working electrode, a platinum sheet (20 mm × 20 mm area) as the counter electrode, and a saturated calomel electrode as the reference electrode. The electrodes were immersed in the modification solution with a fixed electrode spacing of 2 cm. A DC voltage of 1.5 V was applied and deposition was carried out for 10 minutes (magnetic stirring was maintained during the deposition process at a speed of 200 r / min). A uniform MOF-303 modification layer (thickness 5-10 nm, measured by ellipsometry) was formed on the surface of the titanium electrode.

[0054] (4) Post-treatment: After deposition, the electrode is removed and the unbonded MOF particles on the surface are rinsed with anhydrous ethanol. It is then placed in a 90°C forced-air oven and dried for 2 hours. The modified layer is firmly attached to the surface of the titanium electrode, forming a composite structure of "titanium substrate-MOF-303 functional layer".

[0055] 2. Preparation of UiO-66-NH2 modified electrode. The preparation method of UiO-66-NH2 modified electrode includes the following steps: (1) Substrate pretreatment: After polishing the stainless steel electrode (316L material, size 10mm×20mm×0.3mm) with 1000# sandpaper, it is ultrasonically cleaned with deionized water and anhydrous ethanol for 15 minutes each (power 300W) to remove surface oil stains; after drying with nitrogen, it is immersed in 0.1mol / L nitric acid solution for 3 minutes for activation, rinsed with deionized water and dried for later use.

[0056] (2) Atomic layer deposition: A hot-wall atomic layer deposition system was used, with ZrCl4 (purity 99.9%) as the zirconium source, 2-aminoterephthalic acid (purity 98%) as the organic ligand source, and deionized water as the oxygen source. The stainless steel electrode was fixed on the sample stage, the deposition temperature was set to 120℃, and the carrier gas (high-purity nitrogen, purity 99.999%) flow rate was 20 sccm. A single deposition cycle included: ZrCl4 pulse 0.5s → nitrogen purging 10s → 2-aminoterephthalic acid pulse 1s → nitrogen purging 15s → water pulse 0.2s → nitrogen purging 10s, for a total of 50 cycles, forming an amino-functionalized UiO-66-NH2 coating with a thickness of 5nm on the surface of the stainless steel electrode (the modification layer was directly grown on the surface of the stainless steel substrate, and the thickness was measured by X-ray reflectometer).

[0057] (3) Activation: After deposition, the electrode is kept in a vacuum oven at 100°C for 1 hour to activate the amino active sites in the coating, and then naturally cooled to room temperature.

[0058] 3. Preparation of PSP-UiO-66 modified electrode. The preparation method of PSP-UiO-66 modified electrode includes the following steps: (1) Substrate pretreatment: The graphite electrode (size 10mm×20mm×0.5mm) was polished with a soft cloth dipped in alumina polishing powder (particle size 0.3μm) until the surface was smooth. After rinsing with deionized water, it was ultrasonically cleaned with 1mol / L hydrochloric acid and anhydrous ethanol for 10 minutes each (power 300W), and dried at 60℃ for later use.

[0059] (2) Preparation of photosensitive composite: Weigh 1g of UiO-66 powder and disperse it in 50mL of N,N-dimethylformamide (DMF). Sonicate at 300W for 20 minutes. Add photosensitive monomer at a mass ratio of UiO-66 to polyspiropyran (PSP) of 8:1 (i.e., 0.125g PSP). Stir magnetically in an oil bath at 60℃ (400r / min) for 24 hours to allow PSP to be covalently confined to the pores and surface of the UiO-66 framework. After the reaction, centrifuge (8000r / min, 10 minutes), wash with DMF 3 times, and vacuum dry at 60℃ for 12 hours to obtain PSP-UiO-66 composite material.

[0060] (3) Electrophoretic deposition: 0.2g of PSP-UiO-66 composite material was dispersed in 50mL of anhydrous ethanol and ultrasonically treated at 300W for 30 minutes to form a stable dispersion. A pretreated graphite electrode was used as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. The electrode spacing was 2cm. A DC voltage of 1.5V was applied and deposited for 12 minutes to form a photosensitive modification layer with a thickness of 8-12nm on the surface of the graphite electrode (the modification layer tightly covers the surface of the graphite substrate).

[0061] (4) Curing treatment: The deposited electrode is lightly washed with anhydrous ethanol and dried in an 80°C oven for 1.5 hours to make the modified layer form a stable bond with the graphite substrate.

[0062] 4. The preparation method of ion exchange membrane includes the following steps: The PSP-UiO-66 composite material, PVDF, and DMF were mixed under light-protected conditions, ultrasonically dispersed for 30 minutes (300W power), and then magnetically stirred for 2 hours (500r / min) to obtain a uniformly dispersed casting solution. The mass of the PSP-UiO-66 composite material accounted for 2.5% of the mass of the PVDF. The casting solution was poured onto a clean glass substrate using a casting method, and the casting gap was controlled to be 125μm using a casting tool to ensure uniform casting. Preforming: The substrate after coating is placed in a 60℃ forced-air oven for 6 hours in the dark to preform, thus obtaining a preformed film; Vacuum drying: The pre-formed film is transferred to a vacuum oven at 100°C and dried for 12 hours to completely remove the solvent and obtain the formed film; Demolding: After cooling to room temperature, the molded film is peeled off from the glass substrate to obtain a 100μm thick PSP-UiO-66 ion exchange membrane.

[0063] Example 1 Example 1 provides an electrochemical system for recycling positive electrode active materials from spent batteries, referencing... Figure 1It includes a positive electrode material pretreatment device and a metal ion separation device 100, wherein the metal ion separation device 100 includes Co 2+ Electrolytic separation device 110, Ni 2+ Electrolytic separation device 130, Mn 2+ Electrolytic separation device 140, Li + Enrichment device 120, Co 2+ Electrolytic separation device 110 is connected to the outlet of the positive electrode material pretreatment device, Co 2+ Electrolytic separation device 110 and Ni 2+ Electrolytic separation device 130 is connected via salt bridge 150, Ni 2+ Electrolytic separation device 130 and Mn 2+ Electrolytic separation device 140 is connected via salt bridge 150, Mn 2+ Electrolytic separation device 140 and Li + Enrichment device 120 is connected via salt bridge 150, Mn 2+ Electrolytic separation device 140 and Li + The enrichment devices 120 are connected by a salt bridge 150, Co 2+ The cathode 111 of the electrolytic separation device is a MOF-303 modified titanium electrode (10mm × 20mm × 0.5mm), Co 2+ The anode 112 of the electrolytic separation device is a platinum sheet (10mm × 20mm × 0.1mm), Ni 2+ The cathode 131 of the electrolytic separation device is a UiO-66-NH2 modified electrode (10mm × 20mm × 0.3mm), Ni 2+ The anode 132 of the electrolytic separation device is a platinum sheet (10mm × 20mm × 0.1mm); Mn 2+ The anode 141 of the electrolytic separation device is a PSP-UiO-66 modified electrode (10mm × 20mm × 0.5mm), Mn 2+ The cathode 142 of the electrolytic separation device is a high-purity graphite electrode (purity ≥99.9%, size 10mm×20mm×0.5mm). The metal ion separation device 100 also includes multiple conveying pipes 160, each equipped with an electric pump 161. The multiple conveying pipes 160 are located at Co... 2+ Electrolytic separation device 110 and Ni 2+ Between electrolytic separation unit 130, Ni 2+ Electrolytic separation device 130 and Mn 2+ Between electrolytic separation unit 140, Mn 2+ Electrolytic separation device 140 and Li +Between enrichment devices 120. The conveying pipe 160 can transport the solution processed by the previous stage device to the top inlet of the next stage device. Simultaneously, the Co in the system of Example 1... 2+ Electrolytic separation device 110, Ni 2+ Electrolytic separation device 130, Mn 2+ Electrolytic separation device 140, Li + The enrichment device 120 is equipped with a liquid level sensor. When the liquid level is lower than 1 / 2 of the tank height, it will trigger the pre-stage storage tank (containing the pre-treated mixed electrolyte) to automatically replenish the solution, maintain the stable liquid level in the tank, and ensure sufficient separation time.

[0064] Example 1 also provides a method for recycling positive electrode active material from waste batteries, wherein the positive electrode active material from the waste batteries is LiNi. 0.5 Co 0.2 Mn 0.3 O2 recycling methods include: The positive electrode active material from waste batteries is mixed with an acidic solution in a positive electrode material pretreatment device to carry out a leaching reaction, resulting in a metal leaching solution. The specific steps include: LiNi 0.5 Co 0.2 Mn 0.3 The O2 material was pulverized and passed through a 200-mesh sieve. Pretreatment: LiNi 0.5 Co 0.2 Mn 0.3 After the O2 material was pulverized, 1 mol / L H2SO4 and 5% H2O2 (by mass) were added as reducing agents. The mixture was stirred at 60°C for 2 hours, and the residue was removed by filtration to obtain a metal leaching solution. Among these, LiNi... 0.5 Co 0.2 Mn 0.3 The mass-to-volume ratio of O2 material to 1 mol / L H2SO4 solution is 1:15 g / mL; 5% H2O2 solution and LiNi 0.5 Co 0.2 Mn 0.3 The mass ratio of O2 material is 0.07:1.

[0065] Li in metal leaching solution + The concentration was 0.8 g / L, Ni 2+ The concentration was 2.5 g / L, Co 2+ The concentration was 1.2 g / L, Mn 2 + The concentration was 1.0 g / L; The metal leaching solution is transported to Co 2+ In the electrolytic separation device, a pulsed voltage is applied to initiate the first electrolytic reaction, causing Co to...2+ Deposition; The first electrolysis reaction includes: The cathode potential was -0.29V, the pulse voltage frequency was 1Hz, and the pulse voltage duty cycle was 60%. After 2 hours, the Co content in the solution... 2+ The concentration is 0.01 g / L, Co 2+ The separation purity was 99.2%, and the Co / Ni separation factor was 2700.

[0066] Will pass through Co 2+ The solution processed by the electrolytic separation unit is transported to Ni 2+ In the electrolytic separation unit, a second electrolytic reaction takes place, causing Ni to... 2+ Deposition; The second electrolysis reaction includes: a cathode potential of -0.26V, and Ni in the solution after 2 hours. 2+ The concentration is 0.02 g / L, Ni 2+ The separation purity was 99.2%; Will pass through Ni 2+ The solution processed by the electrolytic separation unit is transported to Mn 2+ In the electrolytic separation device, under ultraviolet light irradiation, the third electrolytic reaction is carried out, causing Mn to... 2+ Deposition.

[0067] The third electrolysis reaction includes: setting the anode potential to +1.25V, irradiating the anode with ultraviolet light of 254nm wavelength and 300W power, with the irradiation distance from the light source to the anode surface being 10-15cm, and at this time the light intensity in the anode region is stable at 100-150mW / cm². 2 After 1.5 hours of ultraviolet light irradiation, the Mn content in the solution decreased. 2+ The concentration is 0.01 g / L, Mn 2+ The separation purity was 99.0%; Irradiation method: Directional focused irradiation is adopted, and ultraviolet light is concentrated and projected onto the PSP-UiO-66 modified anode surface through a quartz glass sleeve (acid corrosion resistant) to reduce light energy loss; Stability control: During illumination, the light intensity is monitored in real time using an illuminance meter. If the light intensity decreases to below 100mW / cm², the light intensity will be controlled. 2 The system automatically adjusts the light source power to supplement illumination, ensuring stable lighting conditions for 1.5 hours, ultimately achieving Mn 2+ The concentration was reduced to 0.01 g / L, and the separation purity reached 99.0%.

[0068] Will pass through Mn 2+ The solution processed by the electrolytic separation unit is transported to Li + In the enrichment device, Li is extracted by electrodialysis. + Enrichment, making Li+ The concentration was enriched to 3.5 g / L, and the separation purity reached 99.5%. Li + The refined process parameters for the enrichment electrodialysis step are as follows: the current density is set to 15 mA / cm². 2 To match the ion conductivity of the PSP-UiO-66 ion exchange membrane, avoid concentration polarization, and meet the target total energy consumption of 2.8 kWh / kg metal; the operating voltage is controlled at 2.5V (total membrane stack voltage) to meet the requirements of Li + To facilitate mass transfer and prevent energy spikes, the solution flow rate into the device is set at 20 mL / min to ensure sufficient residence time (8-10 min) within the chamber, guaranteeing adequate mass transfer for Li. + The concentration is enriched to 3.5 g / L, while being compatible with the rated flow of the delivery pipeline and electric pump to ensure stable system operation.

[0069] Example 2 Example 2 provides an electrochemical system for recycling positive electrode active materials from waste batteries. It is otherwise identical to Example 1, except that Ni is omitted from the system of Example 2. 2+ Electrolytic separation device, Mn 2+ Electrolytic separation apparatus, Co in the system of Example 2 2+ Electrolytic separation device and Li + The enrichment devices are connected via salt bridges.

[0070] Example 2 also provides a method for recycling positive electrode active material from waste batteries. The positive electrode active material from waste batteries is LiCoO2 material. The recycling method includes: The LiCoO2 material is mixed with an acidic solution in a positive electrode material pretreatment device to carry out a dissolution reaction and obtain a metal dissolution solution. The specific steps include: crushing the LiCoO2 material and passing it through a 200-mesh sieve. Pretreatment: After pulverizing LiCoO2, 0.8 mol / L H2SO4 and 4% H2O2 (by mass fraction) were added as reducing agents. The mixture was stirred at 55℃ for 1.5 hours, and the residue was removed by filtration to obtain a metal leaching solution. The mass-to-volume ratio of LiCoO2 to 0.8 mol / L H2SO4 was 1:20 g / mL; the mass ratio of 4% H2O2 to LiCoO2 was 0.4:1.

[0071] Li in metal leaching solution + The concentration was 0.7 g / L, Co 2+ The concentration was 1.8 g / L; The metal leaching solution is transported to Co 2+ In the electrolytic separation device, a pulsed voltage is applied to initiate the first electrolytic reaction, causing Co to...2+ Deposition; The first electrolysis reaction used a MOF-303 modified titanium electrode as the cathode, with a cathode potential of -0.28V, a pulse voltage frequency of 1Hz, a pulse voltage duty cycle of 50%, and a current density set at 10mA / cm². 2 After 1.5 hours, the Co in the solution 2+ The concentration was 0.008 g / L, the separation purity was 99.6%, and the energy consumption met the target of 2.5 kWh / kg metal. Will pass through Co 2+ The solution processed by the electrolytic separation unit is transported to Li + In the enrichment device, Li is extracted by electrodialysis. + Enrichment, making Li + The concentration was enriched to 3.2 g / L, and the separation purity reached 99.7%; Li + The enrichment device (electrodialysis) was operated at a voltage of 1.8V and a current density of 12mA / cm² (to match the membrane conductivity and avoid polarization). The solution flow rate into the device was 15mL / min (to ensure sufficient enrichment by maintaining the solution in the chamber for approximately 10 minutes). Ultimately, Li... + The concentration was enriched to 3.2 g / L (separation purity 99.7%), while ensuring a Co recovery rate of 98.5%.

[0072] Comparative Example 1 Everything else is the same as in Example 1, except that a MOF-303 self-supporting block cathode is used as the Co cathode. 2+ Cathode of the electrolytic separation device.

[0073] The preparation method of MOF-303 self-supporting bulk cathode includes: MOF-303 powder pretreatment: Using the same MOF-303 powder (particle size 50-100nm) as in Example 1, ultrasonically cleaned with anhydrous ethanol for 15 minutes (power 300W) to remove residual impurities on the surface, and then vacuum dried at 60°C for 2 hours; Electrode forming: MOF-303 powder and polytetrafluoroethylene (PTFE, binder) are mixed at a mass ratio of 95:5, a small amount of anhydrous ethanol is added to make a paste, and the paste is poured into a mold. The size of the mold is the same as that of the cathode in Example 1. The paste is formed under a pressure of 10MPa for 30 seconds. Post-processing: The formed block electrode is placed in an 80℃ forced-air oven to dry for 4 hours to remove ethanol and enhance the mechanical strength of the electrode. After cooling, it becomes a MOF-303 self-supporting block cathode.

[0074] Co in Comparative Example 1 2+The separation purity was 97.5%, and the Co / Ni separation factor was 2600.

[0075] Comparative Example 2 Everything else is the same as in Example 1, except that: Comparative Example 2 uses a MOF-401 self-supporting block electrode as the Co. 2+ Cathode of the electrolytic separation device.

[0076] The preparation method of the MOF-401 self-supporting bulk electrode in Comparative Example 2 is the same as that of the MOF-303 self-supporting bulk cathode in Comparative Example 1, except that the MOF-303 powder in Comparative Example 1 is replaced with MOF-401 powder of the same particle size.

[0077] Co in Comparative Example 2 2+ The separation purity was 96.8%, and the Co / Ni separation factor was 2400.

[0078] Comparative Example 3 Everything else is the same as in Example 1, except that: Comparative Example 3 uses a UiO-66 self-supporting block electrode as the Co. 2+ Cathode of the electrolytic separation device.

[0079] The preparation method of the UiO-66 self-supporting block electrode in Comparative Example 3 is the same as that of the MOF-303 self-supporting block cathode in Comparative Example 1, except that the MOF-303 powder in Comparative Example 1 is replaced with UiO-66 powder of the same particle size.

[0080] Co in Comparative Example 3 2+ The separation purity was 92.5%, and the Co / Ni separation factor was 350.

[0081] As can be seen from Example 1 and Comparative Examples 1-3, MOF-303 modified titanium electrodes have a positive effect on Co. 2+ Its selectivity is significantly better than that of other MOF electrodes.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0083] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the foregoing claims, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. An electrochemical system for recycling positive electrode active materials from waste batteries, characterized in that, include: Positive electrode material pretreatment device, metal ion separation device; The cathode material pretreatment device is used to dissolve metal ions from the cathode active material of waste batteries. The metal ion separation device includes Co 2+ Electrolytic separation device and Li + Enrichment device, the Co 2+ Electrolytic separation device and the Li + The enrichment device is connected via a salt bridge, and the Co 2+ The electrolytic separation device is connected to the liquid outlet of the positive electrode material pretreatment device; The Co 2+ The cathode of the electrolytic separation device includes a MOF-303 modified titanium electrode.

2. The electrochemical system for recycling positive electrode active materials from waste batteries according to claim 1, characterized in that, The preparation method of the MOF-303 modified titanium electrode includes: The titanium electrode is pretreated to remove the surface oxide layer of the titanium electrode, resulting in a pretreated titanium electrode. MOF-303, 3-aminopropyltriethoxysilane, and an alcohol solvent are mixed and reacted at 25-35°C for 1.9-2.1 hours to obtain a modified solution, wherein the mass ratio of MOF-303 to 3-aminopropyltriethoxysilane is 8-12:

1. Using the pretreated titanium electrode as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode, a three-electrode system was constructed. The electrodes were immersed in the modified solution, with the electrode spacing fixed at 1.8-2.2 cm, and a DC voltage of 1.4-1.6 V was applied. After deposition for 9-11 minutes, MOF-303 modified titanium electrode was obtained.

3. The electrochemical system for recycling positive electrode active materials from waste batteries according to claim 1, characterized in that, The metal ion separation device also includes Ni 2+ Electrolytic separation device, Mn 2+ Electrolytic separation device, wherein the Co 2+ Electrolytic separation device and the Ni 2+ The electrolytic separation unit is connected via a salt bridge, and the Ni 2+ Electrolytic separation device and the Mn 2+ The electrolytic separation device is connected via a salt bridge, and the Mn 2+ Electrolytic separation device and the Li + The enrichment devices are connected via salt bridges.

4. The electrochemical system for recycling positive electrode active materials from waste batteries according to claim 3, characterized in that, The Ni 2+ The cathode of the electrolytic separation device includes a UiO-66-NH2 modified electrode; The preparation method of the UiO-66-NH2 modified electrode includes: A hot-wall atomic layer deposition system was used, with ZrCl4 as the zirconium source, 2-aminoterephthalic acid as the organic ligand source, and water as the oxygen source. A stainless steel electrode was fixed on the sample stage, and the deposition temperature was set to 110-135℃, with a carrier gas flow rate of 18-22 sccm. The carrier gas was nitrogen. A single deposition cycle consisted of: ZrCl4 pulse for 0.4-0.6 s, nitrogen purging for 9.5-10.5 s, 2-aminoterephthalic acid pulse for 0.9-1.1 s, nitrogen purging for 14-16 s, water pulse for 0.19-0.21 s, and nitrogen purging for 9.9-10.1 s, for a total of 48-52 cycles. After deposition, the electrode was kept at 90-110℃ in a vacuum oven for 0.9-1.1 hours and then naturally cooled to room temperature to obtain a UiO-66-NH2 modified electrode.

5. The electrochemical system for recycling positive electrode active materials from waste batteries according to claim 3, characterized in that, The Mn 2+ The anode of the electrolytic separation device includes a PSP-UiO-66 modified electrode; The preparation method of the PSP-UiO-66 modified electrode includes: UiO-66 powder, DMF and PSP are mixed and reacted at 50-70℃ for 23-25 ​​hours. After the reaction is completed, the mixture is washed and dried to obtain PSP-UiO-66 composite material, wherein the mass ratio of UiO-66 to PSP is 6-10:

1. The PSP-UiO-66 composite material was mixed with ethanol at a solid-liquid ratio of 0.1-0.3 g / 50 mL to form a dispersion. A graphite electrode was used as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. The electrode spacing was 1.8-2.2 cm. A DC voltage of 1.4-1.6 V was applied for deposition for 11-13 minutes. The deposited electrode was washed and dried to obtain the PSP-UiO-66 modified electrode.

6. The electrochemical system for recycling positive electrode active materials from spent batteries according to claim 5, characterized in that, The Li + The enrichment device includes a cathode chamber and an anode chamber, and an ion exchange membrane is provided between the cathode chamber and the anode chamber. The material forming the ion exchange membrane includes PSP-UiO-66. The method for preparing the ion exchange membrane includes: The PSP-UiO-66 composite material, PVDF, and DMF are mixed under light-protected conditions to obtain a casting solution, wherein the mass of the PSP-UiO-66 composite material accounts for 2%-3% of the mass of the PVDF. The casting solution is coated onto the substrate using a casting method, with the casting gap controlled to be 100-150 μm. The coated substrate was pre-formed at 59-61℃ in the dark for 5.9-6.1 hours to obtain a pre-formed film; The preformed film is vacuum dried at 95-105°C for 11-13 hours to remove the solvent, thereby obtaining the formed film. After cooling, the molded membrane is peeled off from the substrate to obtain an ion exchange membrane with a thickness of 80-120 μm; And / or, the metal ion separation device further includes multiple delivery pipes, each of which is equipped with an electric pump, and the multiple delivery pipes are respectively located at the Co 2+ Electrolytic separation device and the Ni 2+ Between the electrolytic separation devices, the Ni 2+ Electrolytic separation device and the Mn 2+ Between the electrolytic separation devices, the Mn 2+ Electrolytic separation device and the Li + Between enrichment devices.

7. A method for recycling positive electrode active materials from waste batteries, characterized in that, The electrochemical system for recycling positive electrode active materials from spent batteries according to any one of claims 1-6, wherein the positive electrode active material from spent batteries is a layered oxide, and the recycling method includes: The positive electrode active material of the waste battery is mixed with an acidic solution in a positive electrode material pretreatment device to carry out a leaching reaction and obtain a metal leaching solution. The metal leaching solution is transported to Co 2+ In the electrolytic separation device, a pulsed voltage is applied to initiate the first electrolytic reaction, causing Co to... 2+ Deposition; Will pass through Co 2+ The solution processed by the electrolytic separation unit is transported to Li + In the enrichment device, Li + Enrichment.

8. The method for recycling positive electrode active material of waste batteries according to claim 7, characterized in that, The layered oxides include LiCoO2 and LiNi. x Co y Mn z At least one of O2, wherein, 0 <x<1,0<y<1,0<z<1,x+y+z=1; The parameters of the first electrolysis reaction include: cathode potential of -0.28~-0.30V vs SHE, pulse voltage frequency of 0.8-1.2Hz, pulse voltage duty cycle of 58-62%, and the time of the first electrolysis reaction of 1.5-2 hours.

9. The method for recycling the positive electrode active material of waste batteries according to claim 7 or 8, characterized in that, After the first electrolysis reaction, the method further includes: passing the Co-processed electrolyte through a process... 2+ The solution processed by the electrolytic separation unit is transported to Ni 2+ In the electrolytic separation unit, a second electrolytic reaction takes place, causing Ni to... 2+ Deposition; Will pass through Ni 2+ The solution processed by the electrolytic separation unit is transported to Mn 2+ In the electrolytic separation device, under ultraviolet light irradiation, the third electrolytic reaction is carried out, causing Mn to... 2+ Deposition.

10. The method for recycling positive electrode active materials of waste batteries according to claim 9, characterized in that, The parameters of the second electrolysis reaction include: cathode potential of -0.25~-0.27V vs SHE, and the time of the second electrolysis reaction is 1.9-2.1 hours; And / or, the parameters of the third electrolysis reaction include: anodic potential ≥ 1.23V vs SHE, ultraviolet light power of 290-310W, irradiation distance from the light source to the anode surface of 10-15cm, and ultraviolet light intensity of 100-150mW / cm². 2 The time for the third electrolysis reaction is 1.4-1.6 hours.

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