Composite electrodes for comprehensive recovery of valuable metals, their preparation methods and applications
By designing composite electrodes and using electrolytic reduction leaching technology, the problem of low recovery efficiency of valuable metals in lithium-ion batteries has been solved, achieving efficient, low-cost, and environmentally friendly metal recovery.
Patent Information
- Application Number
- CN202610227633.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-26
- Publication Date
- 2026-05-26
AI Technical Summary
In existing lithium-ion battery recycling processes, the recovery efficiency of valuable metals such as lithium, nickel, cobalt and manganese is low, and there are risks of high energy consumption and environmental pollution. Traditional methods are costly and complex.
A composite electrode, consisting of a conductive polymer-modified material layer and a tubular solid electrolyte body, is used to recover lithium by electrolysis and chemically reduce and leach nickel, cobalt, and manganese under mild conditions. An integrated electro-driven separation and reduction leaching process is designed to reduce energy consumption and the use of chemical reagents.
It achieves efficient recovery of lithium, nickel, cobalt and manganese, reduces energy consumption and environmental risks, reduces the use of chemical reagents, and improves recovery efficiency and purity.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of resource recycling technology, specifically relating to a composite electrode for the comprehensive recycling of valuable metals, its preparation method, and its application. Background Technology
[0002] In recent years, lithium-ion batteries have provided reliable power for various electronic devices due to their high energy density and long lifespan. However, with the rapid increase in the use of lithium-ion batteries, the number of discarded lithium-ion batteries is also increasing daily. These batteries are rich in valuable metals such as lithium, cobalt, and nickel. If they cannot be effectively recycled, it will not only cause a huge waste of resources but also cause serious environmental pollution.
[0003] The recycling of retired cathode materials is often carried out alongside the recycling of lithium-ion batteries. Existing lithium-ion battery recycling processes mainly include pyrometallurgy and hydrometallurgy, which, despite continuous optimization, still have significant shortcomings. Pyrometallurgy converts spent lithium-ion battery cathode materials into metal oxides and alloys through high-temperature smelting. However, its recovery efficiency for Li and Al is low, and it is accompanied by high energy consumption and toxic gas emissions. As the chemical composition of cathodes gradually shifts towards high nickel and low cobalt, the dependence of pyrometallurgical technology on the price of Co becomes a significant limiting factor for its economic feasibility. Hydrometallurgy, on the other hand, directly immerses the cathode material in acidic solutions while adding chemical reducing agents (such as hydrogen peroxide and sodium sulfite) to reduce high-valence nickel and cobalt to easily soluble low-valence metals, thus achieving the co-dissolution of nickel, cobalt, manganese, and lithium. The solution is then further separated into valuable metals through complex steps such as extraction and precipitation. However, its complex process and high solvent consumption lead to high costs and potential secondary pollution risks, limiting the effective recycling of valuable metals from spent lithium-ion batteries. Summary of the Invention
[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a composite electrode for the comprehensive recovery of valuable metals, its preparation method and application, which can not only achieve high-efficiency recovery of valuable metals such as lithium, nickel, cobalt and manganese, but also significantly reduce wastewater treatment costs and environmental risks.
[0005] To achieve this objective, the present invention adopts the following technical solution:
[0006] In a first aspect, the present invention provides a composite electrode for the comprehensive recycling of valuable metals, the composite electrode comprising a positive electrode active layer and a modified matrix layer, the modified matrix layer comprising a tubular solid electrolyte body and a modified material layer disposed on the surface of the tubular solid electrolyte body;
[0007] The modified material layer includes a conductive polymer.
[0008] This invention, through the rational design of the composition and structure of the composite electrode, enables it to recover lithium from the positive electrode active layer in aqueous solution via electro-drive, while simultaneously increasing the redox potential of the delithiated positive electrode material residue. This provides an endogenous reduction driving force for subsequent nickel, cobalt, and manganese recovery, and further reduces energy consumption and the use of chemical reagents, thus contributing to sustainable recycling.
[0009] Specifically, conductive polymers have good ionic conductivity, which not only ensures the rapid transfer of lithium ions in the solution, but also enables flexible connection between the electrolyte and the positive electrode active layer.
[0010] Preferably, the conductive polymer comprises poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (abbreviated as PEDOT:PSS).
[0011] Preferably, the thickness of the modified material layer is 10nm-50nm, for example, it can be 10nm, 20nm, 30nm, 40nm or 50nm, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0012] Preferably, the material of the tubular solid electrolyte body includes an undoped or doped solid electrolyte.
[0013] Preferably, the doped element includes niobium, thereby increasing the ion diffusion rate.
[0014] Preferably, the positive electrode active layer comprises a positive electrode sheet.
[0015] Preferably, the active material of the positive electrode sheet includes a ternary positive electrode material.
[0016] Preferably, the ternary cathode material includes lithium nickel cobalt manganese oxide (LiNi). x Co y Mn 1-x-y O2, where 0 < x < 1, 0 < y < 1, 0 < x + y < 1).
[0017] In a second aspect, the present invention provides a method for preparing a composite electrode for comprehensive recycling of valuable metals as described in the first aspect, the method comprising the following steps:
[0018] Provides modified solutions including conductive polymers;
[0019] The tubular solid electrolyte body is immersed in the modified solution for modification treatment to form a modified material layer, thus obtaining the modified matrix layer.
[0020] The positive electrode active layer and the modified substrate layer are composited to obtain the composite electrode used for the comprehensive recovery of valuable metals.
[0021] This invention utilizes an electrolysis method to efficiently and effectively recover lithium with high purity, minimizing reagent consumption and Li loss, thereby obtaining a high-purity product.
[0022] Preferably, the conductive polymer comprises poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (abbreviated as PEDOT:PSS).
[0023] Preferably, the mass ratio of the poly(3,4-ethylenedioxythiophene) to the poly(styrene sulfonate) is 1:1.
[0024] Preferably, the modified solution further includes an organic solvent.
[0025] Preferably, the organic solvent includes vinyl sulfone.
[0026] Preferably, the mass concentration of the modified solution is 8 g / L-12 g / L, for example, it can be 8 g / L, 9 g / L, 10 g / L, 11 g / L or 12 g / L, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0027] Preferably, the immersion temperature is 25℃-35℃, for example, 25℃, 30℃ or 35℃; the immersion time is 5min-20min, for example, 5min, 10min, 15min, 20min, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0028] In this invention, the thickness of the modified material layer is controlled by changing the impregnation conditions, thereby achieving the technical effects of flexible connection and good ionic conductivity.
[0029] Thirdly, the present invention provides a method for the comprehensive recycling of valuable metals, the method comprising the following steps:
[0030] The composite electrode for comprehensive recovery of valuable metals as described in the first aspect is connected to the positive terminal of an external power source, and the inert electrode is connected to the negative terminal of an external power source. Electrolysis is performed using deionized water as the electrolyte to recover lithium from the positive electrode active layer and obtain delithiated material.
[0031] The delithiated material is chemically reduced and leached to comprehensively recover nickel, cobalt, and manganese from the positive electrode active layer.
[0032] To address the following problems with existing processes: (1) Traditional wet leaching processes rely on large amounts of expensive chemical reducing agents to reduce and dissolve high-valence nickel, cobalt, and manganese, resulting in high recycling costs; (2) Existing electrochemical separation schemes, if directly applied to cathode active materials, can efficiently extract lithium, but the chemical properties of the residual high-valence nickel, cobalt, and manganese oxides after delithiation are stable, and the lattice shrinks, resulting in low activity. Therefore, the electrochemical enrichment technology has not actually solved the problem of efficient leaching of nickel, cobalt, and manganese. Based on this, this invention first utilizes electrochemical delithiation to convert the cathode active material into a delithiation state material with high activity and high oxidation potential (nickel, cobalt, and manganese are in a high-valence state, such as Ni). 3+ / Co 3+ The aforementioned delithiated materials, acting as strong oxidants, can react with inexpensive reducing agents or reducing wastes (such as Fe). 2+ A rapid redox reaction occurs, thereby enabling efficient and low-consumption recovery of nickel, cobalt, and manganese under mild conditions.
[0033] Preferably, the electrolysis is performed using a pulsed current.
[0034] Preferably, the frequency of the pulse current is 3Hz-4Hz, for example, 3Hz, 3.5Hz or 4Hz; the duty cycle of the pulse current is 50%-60%, for example, 50%, 52%, 55%, 58% or 60%, etc., not limited to the listed values, and other unlisted values within this range are also applicable.
[0035] Preferably, the pulse voltage applied to the anode during the electrolysis process is 4.0V-4.3V, for example, it can be 4.0V, 4.1V, 4.2V or 4.3V, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0036] Preferably, the liquid-to-solid ratio of the chemical reduction leaching is 5:1-10:1, for example, it can be 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0037] Preferably, the temperature of the chemical reduction leaching is 60℃-80℃, for example, 60℃, 65℃, 70℃, 75℃ or 80℃; the time of the chemical reduction leaching is 60min-120min, for example, 60min, 80min, 100min or 120min, etc., not limited to the listed values, and other unlisted values within this range are also applicable.
[0038] Preferably, the chemical reduction leaching process uses an acid solution and a reducing agent.
[0039] In this invention, the acid solution exemplarily includes a sulfuric acid solution with a concentration of 1 mol / L to 2 mol / L, such as 1 mol / L, 1.2 mol / L, 1.5 mol / L, 1.8 mol / L, or 2 mol / L, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0040] In this invention, the concentration of the reducing agent is 1 to 1.5 times the theoretical amount, for example, it can be 1, 1.2 or 1.5 times, etc., and is not limited to the listed values. Other unlisted values within this range are also applicable.
[0041] Preferably, the specific reaction formula in the method for comprehensive recovery of valuable metals provided by the present invention is as follows:
[0042] (1) Electrolysis: LiNi x Co y Mn 1-x-y O2→Li 1-m Ni x Co y Mn 1-x-y O2+mLi + +me − ;
[0043] (2) Reduction leaching: Li 1-m Ni x Co y Mn 1-x-y O2+H + +Reducing agent→Ni 2+ +Co 2+ +Mn 2+ +(1-m)Li + +H2O.
[0044] Fourthly, the present invention provides an application of the method for comprehensive recycling of valuable metals as described in the third aspect, wherein the method for comprehensive recycling of valuable metals is used in the preparation of electrode materials.
[0045] The numerical range described in this invention includes not only the point values listed above, but also any point values within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values included in the range.
[0046] Compared with the prior art, the present invention has the following beneficial effects:
[0047] This invention provides a composite electrode for the comprehensive recovery of valuable metals, which enables the recovery of lithium in the positive electrode active layer in aqueous solution through electro-drive, while increasing the redox potential of the delithiated positive electrode material residue. This provides an endogenous reduction driving force for subsequent nickel, cobalt and manganese recovery, and further reduces energy consumption and the use of chemical reagents, thus contributing to sustainable recovery.
[0048] On the one hand, by depositing the modified material layer on the surface of the tubular solid electrolyte body, the present invention not only achieves a flexible connection between the electrolyte and the positive electrode active layer, but also maintains structural stability. Furthermore, the modified material layer also possesses high lithium-ion conductivity, ensuring rapid lithium-ion transfer in the solution.
[0049] On the other hand, this invention designs an integrated process of electric-driven separation and reduction leaching, which enables the comprehensive recovery of valuable metals such as lithium, nickel, cobalt and manganese, thereby reducing energy consumption and the use of chemical reagents, and contributing to sustainable recycling. Detailed Implementation
[0050] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.
[0051] Example 1
[0052] This embodiment provides a composite electrode and its preparation method, as well as a method for using the composite electrode for comprehensive recovery of valuable metals, specifically including the following steps:
[0053] S1. Preparation of the modified solution: The modified solution is a vinyl sulfone solution of PEDOT and PSS, with a mass concentration of 10 g / L, wherein the mass ratio of PEDOT to PSS is 1:1.
[0054] Preparation of modified LLZTO ceramic tubes: In a fume hood, LLZTO ceramic tubes are immersed in a modification solution at 30°C for 10 minutes. The immersed LLZTO ceramic tubes are then placed in a vacuum drying oven for drying. After drying, a modified material layer is formed, resulting in a modified matrix layer with a thickness of 30 nm.
[0055] S2. In the glove box, the lithium nickel cobalt manganese oxide positive electrode sheets of the waste lithium-ion batteries are moistened with electrolyte for later use. The electrolyte is made by dissolving lithium hexafluorophosphate at a concentration of 1 mol / L in ethylene carbonate and diethyl carbonate at a volume ratio of 1:1.
[0056] S3. In the glove box, the wetted lithium nickel cobalt manganese oxide positive electrode sheet prepared in step S2 is evenly wound around the outer surface of the modified LLZTO ceramic tube. Then, the modified LLZTO ceramic tube with the lithium nickel cobalt manganese oxide positive electrode sheet is sealed in a stainless steel shell. The glove box is then removed. The stainless steel shell that is in close contact with the lithium nickel cobalt manganese oxide positive electrode sheet is then connected to the positive terminal of an external power source.
[0057] S4. Deionized water is injected into the modified LLZTO ceramic tube as the initial solution for lithium ion enrichment, and a platinum electrode is introduced into the deionized water in the modified LLZTO ceramic tube. The platinum electrode is connected to the negative terminal of the external power supply, and electrolysis is performed for 6 hours with a pulse current of 3.5Hz and a duty cycle of 55%. During the electrolysis process, a pulse voltage of 4.2V is applied to the anode terminal.
[0058] S5. Due to the voltage between the lithium nickel cobalt manganese oxide cathode and the platinum electrode, the modified LLZTO ceramic tube extracts Li from the lithium nickel cobalt manganese oxide cathode on the anode side. + Simultaneously, at the cathode, deionized water is electrolyzed into OH-. - and H + Ions, OH - With extracted Li + LiOH is formed in the cathode solution; at the same time, H + Ions gain electrons from an external circuit, leading to the generation and recovery of H2 gas, which in turn drives the Li-ion exchange in the lithium nickel cobalt manganese oxide cathode. + The lithium hydroxide solution is transported from the anode to the cathode chamber via a modified LLZTO ceramic tube, where it is enriched to form a LiOH reaction solution. When the voltage curvature (dV / ds) between the lithium nickel cobalt manganese oxide cathode and deionized water increases instantaneously, the power supply is cut off. At this point, the LiOH enriched in the modified LLZTO ceramic tube is... + The LiOH reaction solution is recycled to recover lithium from the positive electrode, thus obtaining the delithiated material.
[0059] S6. Add 100g of the above-mentioned delithiated material and sodium metabisulfite to a sulfuric acid solution for chemical reduction leaching. The concentration of sodium metabisulfite is 1.2 times the theoretical amount, the liquid-to-solid ratio is 7:1, the concentration of sulfuric acid solution is 1mol / L, the temperature of chemical reduction leaching is 70℃, and the time of chemical reduction leaching is 90min. In this way, nickel, cobalt and manganese in the positive electrode active layer are comprehensively recovered.
[0060] Example 2
[0061] This embodiment provides a composite electrode and its preparation method, as well as a method for using the composite electrode for comprehensive recovery of valuable metals, specifically including the following steps:
[0062] S1. Preparation of the modified solution: The modified solution is a vinyl sulfone solution of PEDOT and PSS, with a mass concentration of 8 g / L, wherein the mass ratio of PEDOT to PSS is 1:1.
[0063] Preparation of modified LLZTO ceramic tubes: In a fume hood, LLZTO ceramic tubes are immersed in a modification solution at 25°C for 20 minutes. The immersed LLZTO ceramic tubes are then placed in a vacuum drying oven for drying. After drying, a modified material layer is formed, resulting in a modified matrix layer with a thickness of 10 nm.
[0064] S2. In the glove box, the lithium nickel cobalt manganese oxide positive electrode sheets of the waste lithium-ion batteries are moistened with electrolyte for later use. The electrolyte is made by dissolving lithium hexafluorophosphate at a concentration of 1 mol / L in ethylene carbonate and diethyl carbonate at a volume ratio of 1:1.
[0065] S3. In the glove box, the wetted lithium nickel cobalt manganese oxide positive electrode sheet prepared in step S2 is evenly wound around the outer surface of the modified LLZTO ceramic tube. Then, the modified LLZTO ceramic tube with the lithium nickel cobalt manganese oxide positive electrode sheet is sealed in a stainless steel shell. The glove box is then removed. The stainless steel shell that is in close contact with the lithium nickel cobalt manganese oxide positive electrode sheet is then connected to the positive terminal of an external power source.
[0066] S4. Deionized water is injected into the modified LLZTO ceramic tube as the initial solution for lithium ion enrichment, and a platinum electrode is introduced into the deionized water in the modified LLZTO ceramic tube. The platinum electrode is connected to the negative terminal of the external power supply, and electrolysis is performed for 6 hours with a pulse current of 3Hz and a duty cycle of 50%. During the electrolysis process, a pulse voltage of 4.0V is applied to the anode terminal.
[0067] S5. Due to the voltage between the lithium nickel cobalt manganese oxide cathode and the platinum electrode, the modified LLZTO ceramic tube extracts Li from the lithium nickel cobalt manganese oxide cathode on the anode side. + Simultaneously, at the cathode, deionized water is electrolyzed into OH-. - and H + Ions, OH - With extracted Li + LiOH is formed in the cathode solution; at the same time, H + Ions gain electrons from an external circuit, leading to the generation and recovery of H2 gas, which in turn drives the Li-ion exchange in the lithium nickel cobalt manganese oxide cathode. + The lithium hydroxide solution is transported from the anode to the cathode chamber via a modified LLZTO ceramic tube, where it is enriched to form a LiOH reaction solution. When the voltage curvature (dV / ds) between the lithium nickel cobalt manganese oxide cathode and deionized water increases instantaneously, the power supply is cut off. At this point, the LiOH enriched in the modified LLZTO ceramic tube is... +The LiOH reaction solution is recovered to comprehensively recover lithium from the positive electrode, thus obtaining the delithiated material.
[0068] S6. Add 100g of the above-mentioned delithiated material and sodium metabisulfite to a sulfuric acid solution for chemical reduction leaching. The concentration of sodium metabisulfite is 1.2 times the theoretical amount, the liquid-to-solid ratio is 5:1, the concentration of sulfuric acid solution is 1mol / L, the temperature of chemical reduction leaching is 60℃, and the time of chemical reduction leaching is 120min. In this way, nickel, cobalt and manganese in the positive electrode active layer are comprehensively recovered.
[0069] Example 3
[0070] This embodiment provides a composite electrode and its preparation method, as well as a method for using the composite electrode for comprehensive recovery of valuable metals, specifically including the following steps:
[0071] S1. Preparation of the modified solution: The modified solution is a sulfone solution of PEDOT and PSS, with a mass concentration of 12 g / L, wherein the mass ratio of PEDOT to PSS is 1:1.
[0072] Preparation of modified LLZTO ceramic tubes: In a fume hood, LLZTO ceramic tubes are immersed in a modification solution at 35°C for 5 minutes. After immersion, the LLZTO ceramic tubes are placed in a vacuum drying oven for drying. After drying, a modified material layer is formed, resulting in a modified matrix layer with a thickness of 50 nm.
[0073] S2. In the glove box, the lithium nickel cobalt manganese oxide positive electrode sheets of the waste lithium-ion batteries are moistened with electrolyte for later use. The electrolyte is made by dissolving lithium hexafluorophosphate at a concentration of 1 mol / L in ethylene carbonate and diethyl carbonate at a volume ratio of 1:1.
[0074] S3. In the glove box, the wetted lithium nickel cobalt manganese oxide positive electrode sheet prepared in step S2 is evenly wound around the outer surface of the modified LLZTO ceramic tube. Then, the modified LLZTO ceramic tube with the lithium nickel cobalt manganese oxide positive electrode sheet is sealed in a stainless steel shell. The glove box is then removed. The stainless steel shell that is in close contact with the lithium nickel cobalt manganese oxide positive electrode sheet is then connected to the positive terminal of an external power source.
[0075] S4. Deionized water is injected into the modified LLZTO ceramic tube as the initial solution for lithium ion enrichment, and a platinum electrode is introduced into the deionized water in the modified LLZTO ceramic tube. The platinum electrode is connected to the negative terminal of the external power supply, and electrolysis is performed for 6 hours with a pulse current of 4Hz and a duty cycle of 60%. During the electrolysis process, a pulse voltage of 4.3V is applied to the anode terminal.
[0076] S5. Due to the voltage between the lithium nickel cobalt manganese oxide cathode and the platinum electrode, the modified LLZTO ceramic tube extracts Li from the lithium nickel cobalt manganese oxide cathode on the anode side. + Simultaneously, at the cathode, deionized water is electrolyzed into OH-. - and H + Ions, OH - With extracted Li + LiOH is formed in the cathode solution; at the same time, H + Ions gain electrons from an external circuit, leading to the generation and recovery of H2 gas, which in turn drives the Li-ion exchange in the lithium nickel cobalt manganese oxide cathode. + The lithium hydroxide solution is transported from the anode to the cathode chamber via a modified LLZTO ceramic tube, where it is enriched to form a LiOH reaction solution. When the voltage curvature (dV / ds) between the lithium nickel cobalt manganese oxide cathode and deionized water increases instantaneously, the power supply is cut off. At this point, the LiOH enriched in the modified LLZTO ceramic tube is... + The LiOH reaction solution is recovered to comprehensively recover lithium from the positive electrode, thus obtaining the delithiated material.
[0077] S6. Add 100g of the above-mentioned delithiated material and sodium metabisulfite to a sulfuric acid solution for chemical reduction leaching. The concentration of sodium metabisulfite is 1.2 times the theoretical amount, the liquid-to-solid ratio is 10:1, the concentration of sulfuric acid solution is 2mol / L, the temperature of chemical reduction leaching is 80℃, and the time of chemical reduction leaching is 60min. In this way, nickel, cobalt and manganese in the positive electrode active layer are comprehensively recovered.
[0078] Example 4
[0079] The difference between this embodiment and embodiment 1 is that in step S1, the mass ratio of PEDOT:PSS is 1:2, while all other aspects are the same as in embodiment 1.
[0080] Example 5
[0081] The difference between this embodiment and embodiment 1 is that in step S1, the mass ratio of PEDOT:PSS is 2:1, while all other aspects are the same as in embodiment 1.
[0082] Example 6
[0083] The difference between this embodiment and Embodiment 1 is that in step S1, the thickness of the modified material layer is adjusted to 5 nm by changing the soaking time; all other aspects are the same as in Embodiment 1.
[0084] Example 7
[0085] The difference between this embodiment and Embodiment 1 is that in step S1, the thickness of the modified material layer is adjusted to 60 nm by changing the soaking time; all other aspects are the same as in Embodiment 1.
[0086] Example 8
[0087] The difference between this embodiment and Embodiment 1 is that, in step S4, the pulse voltage applied to the anode during electrolysis is 3.7V, while all other aspects are the same as in Embodiment 1.
[0088] Comparative Example 1
[0089] This comparative example provides an LLZTO ceramic tube without any modification as an electrode.
[0090] Comparative Example 2
[0091] The difference between this comparative example and Example 1 is that the modified material layer does not include PSS, and the addition of PSS is omitted in step S1. Otherwise, it is the same as Example 1.
[0092] Comparative Example 3
[0093] This comparative example provides a reduction leaching scheme for lithium enrichment without electrochemical enrichment, specifically including the following steps:
[0094] The lithium nickel cobalt manganese oxide positive electrode sheets of waste lithium-ion batteries were chemically reduced and leached in a sulfuric acid solution with a liquid-to-solid ratio of 7:1, a sulfuric acid solution concentration of 1 mol / L, a chemical reduction and leaching temperature of 70℃, and a chemical reduction and leaching time of 90 min. After the chemical reduction and leaching was completed, water leaching was performed to comprehensively recover the metals in the positive electrode active layer.
[0095] Test conditions
[0096] The content of each element in the deionized aqueous solution and the leachate was characterized by inductively coupled plasma (ICP) to obtain the liquid recovery rate. The test results are shown in Table 1.
[0097] Table 1
[0098]
[0099] As can be seen from Table 1, the following conclusions can be drawn:
[0100] (1) As can be seen from Examples 1 to 3, the composite electrode for comprehensive recovery of valuable metals provided by the present invention, its preparation method and application, can achieve selective lithium extraction and efficient recovery of nickel, cobalt and manganese after combining electrochemical lithium extraction and chemical reduction leaching, wherein the recovery rates of nickel, cobalt and manganese lithium are all greater than 94%.
[0101] (2) As can be seen from the combination of Example 1, Example 4, Example 5 and Comparative Example 2, the present invention selects a specific mass ratio of PEDOT:PSS, which fully utilizes the conductivity of PEDOT and the activation of PSS, improves the ion conductivity of the modified material layer, and thus improves the metal recovery rate.
[0102] (3) Combining Examples 1, 6, and 7, it can be seen that the thickness of the modified material layer is small, making it difficult to maintain the flexible connection between the positive electrode active material and the solid electrolyte. The thickness of the modified material layer is large, increasing the length of the ion channel. Both reduce the ion conductivity and are not conducive to the lithium release and oxidation process of the positive electrode active material.
[0103] (4) As can be seen from Examples 1 and 8, if the voltage applied to the anode is insufficient during the electrolysis process, it is impossible to deeply delithiate and cannot guarantee the deep oxidation of the positive electrode active material. Therefore, the preferred technical solution of the present invention is a pulse voltage of 4.0V-4.3V to further improve the metal recovery rate.
[0104] (5) As can be seen from Example 1 and Comparative Example 1, the present invention modifies the ceramic tube and adds a modified material layer on the surface, which is beneficial to the flexible bonding between the solid electrolyte and the positive electrode active material, improves the ion conductivity, and thus promotes the recovery of metals.
[0105] (6) As can be seen from Example 1 and Comparative Example 3, the technical solution of the present invention combines electrochemical selective lithium extraction and reductive leaching. While reducing high-valence nickel, cobalt and manganese in the reductive acid leaching stage, it can effectively dissolve the metal, thereby comprehensively improving the metal recovery rate.
[0106] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.
Claims
1. A composite electrode for the comprehensive recovery of valuable metals, the composite electrode comprising a positive electrode active layer and a modified substrate layer, characterized in that, The modified matrix layer includes a tubular solid electrolyte body and a modified material layer disposed on the surface of the tubular solid electrolyte body. The modified material layer includes a conductive polymer.
2. The composite electrode according to claim 1, characterized in that, The conductive polymer includes poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate). Preferably, the thickness of the modified material layer is 10nm-50nm.
3. The composite electrode according to claim 1 or 2, characterized in that, The tubular solid electrolyte body is made of undoped or doped solid electrolyte. Preferably, the doping element includes niobium.
4. The composite electrode according to any one of claims 1-3, characterized in that, The positive electrode active layer includes a positive electrode sheet; Preferably, the active material of the positive electrode sheet includes a ternary positive electrode material; Preferably, the ternary cathode material includes lithium nickel cobalt manganese oxide.
5. A method for preparing a composite electrode for comprehensive recovery of valuable metals as described in any one of claims 1-4, characterized in that, The preparation method includes the following steps: Provides modified solutions including conductive polymers; The tubular solid electrolyte body is immersed in the modified solution for modification treatment to form a modified material layer, thus obtaining the modified matrix layer. The positive electrode active layer and the modified substrate layer are composited to obtain the composite electrode used for the comprehensive recovery of valuable metals.
6. The preparation method according to claim 5, characterized in that, The conductive polymer includes poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate). Preferably, the mass ratio of the poly(3,4-ethylenedioxythiophene) to the poly(styrene sulfonate) is 1:1; Preferably, the modified solution further includes an organic solvent; Preferably, the organic solvent includes vinyl sulfone; Preferably, the mass concentration of the modified solution is 8 g / L-12 g / L; Preferably, the immersion temperature is 25℃-35℃, and the immersion time is 5min-20min.
7. A method for comprehensive recycling of valuable metals, characterized in that, The method includes the following steps: The composite electrode for comprehensive recovery of valuable metals as described in any one of claims 1-4 is connected to the positive terminal of an external power source, and the inert electrode is connected to the negative terminal of an external power source. Electrolysis is performed using deionized water as the electrolyte to recover lithium from the positive electrode active layer and obtain delithiated material. The delithiated material is chemically reduced and leached to comprehensively recover nickel, cobalt, and manganese from the positive electrode active layer.
8. The method according to claim 7, characterized in that, The electrolysis is performed using pulsed current; Preferably, the frequency of the pulse current is 3Hz-4Hz, and the duty cycle of the pulse current is 50%-60%. Preferably, the pulse voltage applied to the anode during the electrolysis process is 4.0V-4.3V.
9. The method according to claim 7 or 8, characterized in that, The liquid-to-solid ratio of the chemical reduction leaching is 5:1-10:1; Preferably, the temperature of the chemical reduction leaching is 60℃-80℃, and the time of the chemical reduction leaching is 60min-120min.
10. The application of a method for the comprehensive recovery of valuable metals as described in any one of claims 7-9, characterized in that, The method for comprehensively recovering valuable metals is used in the preparation of electrode materials.