Recycling method of copper-lithium composite belt

Abstract

The invention discloses a recovery method of a copper-lithium composite belt, which belongs to the technical field of lithium batteries, and comprises the following steps: placing the copper-lithium composite belt in an inert liquid, the boiling point of which is greater than or equal to 240 DEG C and the density of which is greater than or equal to 0.6 g / cm < 3 >; the inert liquid is heated, so that lithium in the copper-lithium composite belt is converted into liquid lithium, the liquid lithium floats to the surface of the inert liquid, and the copper substrate after lithium separation is recycled; mixing liquid lithium with the to-be-lithiated powder to obtain lithiated powder; placing the lithiated powder in an acid solution for reaction, and separating out a lithium-containing solution; sodium carbonate is added into the lithium-containing solution, the pH value is adjusted to be alkaline, residues are separated out, and lithium carbonate is recycled. The technical effect of reducing the risk and energy consumption in the lithium metal battery recycling process is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of lithium batteries, and in particular to a method for recycling copper-lithium composite strips. Background Art

[0002] Copper-lithium composite ribbon is one of the anode materials available for lithium metal batteries. However, due to the extremely strong activity of metallic lithium, how to safely recycle it becomes a key issue.

[0003] Currently, there are few ways to recycle copper-lithium composite strips, and they are usually complicated. There are usually risks such as the generation of hydrogen, which may cause thermal runaway. Or higher temperatures are required for recycling, resulting in greater energy consumption. Summary of the invention

[0004] The main purpose of the present application is to provide a method for recovering copper-lithium composite strips, aiming to solve the technical problems of high thermal runaway risk and high energy consumption in current recovery methods.

[0005] To achieve the above object, the present application provides a method for recovering a copper-lithium composite strip, comprising:

[0006] The copper-lithium composite tape is placed in an inert liquid, wherein the boiling point of the inert liquid is greater than or equal to 240° C. and the density is greater than or equal to 0.6 g / cm 3 ;

[0007] Heating the inert liquid to convert lithium in the copper-lithium composite belt into liquid lithium, which floats to the surface of the inert liquid, and recovering the copper substrate after lithium separation;

[0008] Mixing the liquid lithium with the powder to be lithiated to obtain a lithiated powder;

[0009] placing the lithiated powder in an acid solution for reaction, and separating a lithium-containing solution;

[0010] Sodium carbonate is added to the lithium-containing solution to adjust the pH value to alkaline, slag is separated, and lithium carbonate is recovered.

[0011] In some embodiments, the inert liquid includes paraffin oil, diphenyl ether, benzyl benzoate, or dibutyl phthalate.

[0012] In some embodiments, the heating temperature of the inert liquid is 180°C-220°C.

[0013] In some embodiments, the step of heating the inert liquid to convert lithium in the copper-lithium composite belt into liquid lithium and float it to the surface of the inert liquid is further supplemented by ultrasonic treatment, and the frequency of the ultrasonic treatment is 20kHz-40kHz.

[0014] In some embodiments, the powder to be lithiated includes graphite, hard carbon or amorphous carbon.

[0015] In some embodiments, the molar ratio between the powder to be lithiated and the liquid lithium is 1.2:1-1.5:1.

[0016] In some embodiments, the concentration of hydrogen ions in the acid solution is 1 mol / L-4 mol / L.

[0017] In some embodiments, in the step of placing the lithiated powder in an acid solution for reaction, the reaction temperature is set at 50° C.-95° C. and the stirring speed is set at 100 r / min-300 r / min.

[0018] In some embodiments, the step of adding sodium carbonate to the lithium-containing solution, adjusting the pH value to alkaline, separating the slag, and recovering lithium carbonate, adjusts the pH value to 9-11, sets the reaction temperature to 50°C-95°C, and assists with stirring at 100r / min-300r / min.

[0019] In some embodiments, the lithium-free powder after separation of the lithium-containing solution is recycled as the powder to be lithiated.

[0020] The copper-lithium composite tape recovery method provided in the present application first places the copper-lithium composite tape in an inert liquid, wherein the boiling point of the inert liquid is greater than or equal to 240° C. and the density is greater than or equal to 0.6 g / cm 3 The inert liquid does not chemically react with lithium and copper, has a high boiling point, which is above the melting point of lithium, and has a greater density than lithium; the inert liquid is heated to convert the lithium in the copper-lithium composite belt into liquid lithium, which floats to the surface of the inert liquid, and the copper substrate after lithium separation is recovered. Due to the high boiling point and high density of the inert liquid, the lithium in the copper-lithium composite belt is melted and converted into liquid under heating conditions and then floats to the surface, and the copper substrate that has not floated can be separated; the liquid lithium is mixed with the powder to be lithiated to obtain to the lithiated powder, the liquid lithium is absorbed by the powder to be lithiated, and the lithium is embedded in the structure of the powder to be lithiated; the lithiated powder is placed in an acid solution to react, and a lithium-containing solution is separated, and the lithium element in the lithiated powder reacts with the acid solution to form lithium ions dissolved in the acid solution, while the powder to be lithiated is insoluble in the acid solution, thereby transferring the lithium element to the separated lithium-containing solution; sodium carbonate is added to the lithium-containing solution, the pH value is adjusted to alkaline, the slag is separated, and lithium carbonate is recovered. In an alkaline environment, lithium ions combine with carbonate ions to generate lithium carbonate that is recovered. Therefore, the reaction temperature required for the recovery method of the present application is relatively low, which can reduce the risk of thermal runaway and reduce the energy consumption of recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present drawings or related technologies, the drawings required for use in the embodiments or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present drawings. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0022] Figure 1 This is a schematic diagram of the process of the first embodiment of the method for recovering copper-lithium composite strips according to the present application;

[0023] Figure 2 This is a schematic flow chart of the second embodiment of the method for recovering copper-lithium composite strips according to an embodiment of the present application.

[0024] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0025] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0026] Hereinafter, the embodiment of the method for recovering the copper-lithium composite belt of the present application is specifically disclosed in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0027] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0028] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0029] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and understandable, the technical solution of the present application is further described below in conjunction with the accompanying drawings and embodiments. However, the present application is not limited to the listed embodiments, and should also include any other known changes within the scope of the rights claimed in the present application.

[0030] As the negative electrode of metal lithium batteries, the copper-lithium composite strip is currently recycled by reacting it into lithium carbonate and lithium hydroxide through mixed gas, but there are risks of hydrogen generation, excessive reaction and thermal runaway. Another way is to separate lithium vapor through high-temperature distillation for recycling, but there are disadvantages of high energy consumption and great safety risks.

[0031] The present application scheme utilizes the large difference between the melting point of metallic lithium and the copper substrate, and heats the metallic lithium into a molten state. Since the density of metallic lithium is low, it can float to the liquid surface and can be easily recovered. The liquid metallic lithium is then mixed with a material that is highly stable and can be slowly lithiated to convert the metallic lithium into a stable compound. After the lithium-containing solution is obtained by acid leaching, the lithium carbonate precipitate can be prepared by soda ash for recovery.

[0032] Based on this, the present application embodiment provides a method for recovering a copper-lithium composite belt, referring to Figure 1 , Figure 1This is a schematic diagram of a first embodiment of a method for recycling a copper-lithium composite belt of the present application. In this embodiment, the method for recycling a copper-lithium composite belt includes the following steps S10 to S50:

[0033] Step S10, placing the copper-lithium composite tape in an inert liquid, wherein the boiling point of the inert liquid is greater than or equal to 240° C. and the density of the inert liquid is greater than or equal to 0.6 g / cm 3 ;

[0034] Copper-lithium composite tape refers to a material that can be used as a negative electrode material for lithium metal batteries. It is understood that the copper-lithium composite tape may include a copper current collector and a lithium layer, and the copper current collector and the lithium layer may be connected by mechanical bonding. Inert liquid refers to a liquid that does not chemically react with lithium. The chemical properties of lithium are relatively active, and the chemical properties of copper are relatively stable, so inert liquids do not chemically react with copper. The melting point of lithium is 180.5°C and the density is 0.534g / cm 3 The melting point of copper is 1083.4°C and its density is 8.960g / cm 3 The boiling point of the inert liquid is greater than or equal to 240°C, which is above the melting point of lithium. And the density of the inert liquid is greater than or equal to 0.6 g / cm 3 , and has a higher density than lithium. The lithium in the copper-lithium composite tape can react chemically when placed in the air, so the copper-lithium composite tape can be placed in an inert liquid under a protective atmosphere.

[0035] Step S20, heating the inert liquid to convert the lithium in the copper-lithium composite strip into liquid lithium, and floating it to the surface of the inert liquid, and recovering the copper substrate after lithium separation;

[0036] By heating the inert liquid, heat can be transferred from the inert liquid to the copper-lithium composite belt. When the temperature reaches above the melting point of lithium, the state of lithium begins to change from solid to liquid. Maintaining heating for a certain period of time can completely melt the lithium in the copper-lithium composite belt. When lithium melts into liquid, since its density is lower than that of the inert liquid, it will float to the surface of the inert liquid, thereby stripping the lithium from the copper-lithium composite belt. The remaining copper substrate can sink to the bottom of the inert liquid due to its high density. The floating liquid lithium and the sinking copper substrate can be collected separately, the copper substrate can be directly recovered, and the liquid lithium can be recovered through subsequent process steps.

[0037] In some embodiments, the inert liquid includes paraffin oil, diphenyl ether, benzyl benzoate or dibutyl phthalate. It is understood that the above-mentioned types of inert liquids all meet the requirements of boiling point and density and can be arbitrarily selected as the liquid medium for recovering the copper-lithium composite belt.

[0038] In some embodiments, the heating temperature of the inert liquid is 180°C-220°C. For example, the heating temperature of the inert liquid can be 180°C, 190°C, 200°C, 210°C, 220°C or within the range of any of the above values. It is understandable that the heating temperature of the inert liquid is at least 180°C, because lithium begins to melt under the condition of reaching this temperature. The maximum value of the heating temperature is set to 220°C, which is selected according to the boiling point of the inert liquid. If the heating temperature exceeds the boiling point of the inert liquid, the inert liquid will volatilize, and the toxic inert gas volatilizes into the air, which is easy to cause harm to the human body, and the boiling of the inert liquid will also produce certain dangers. Therefore, by controlling the heating temperature within a suitable range, a good recovery effect can be obtained and the danger can be reduced.

[0039] In some embodiments, ultrasonic treatment is also used, and the frequency of ultrasonic treatment is 20kHz-40kHz. For example, the frequency of ultrasonic treatment can be 20kHz, 25kHz, 30kHz, 35kHz, 40kHz or in the range of any of the above values. It is understood that ultrasonic treatment can accelerate the speed of liquid lithium being peeled off from the copper-lithium composite belt and floating to the surface of the inert liquid. The higher the frequency of ultrasonic treatment, the higher the severity of vibration. Selecting a suitable ultrasonic treatment frequency can assist the separation of liquid lithium.

[0040] Step S30, mixing the liquid lithium with the powder to be lithiated to obtain the lithiated powder;

[0041] The powder to be lithiated refers to a material that can be lithiated under the reaction conditions of the embodiments of the present application. It is understood that liquid lithium is mixed with the powder to be lithiated, and the powder to be lithiated is lithiated, a chemical reaction occurs between the two, and lithium enters the structure of the powder to be lithiated to obtain a lithiated powder. The chemical reaction between liquid lithium and the powder to be lithiated can refer to the embedding process of lithium in the negative electrode during the cycle of a lithium battery, and the lithiated powder is a compound formed after lithium embedding.

[0042] In some embodiments, the process of mixing the liquid lithium with the powder to be lithiated is supplemented by mechanical stirring. Mechanical stirring can promote uniform mixing between the liquid lithium and the powder to be lithiated, and accelerate the absorption of the liquid lithium by the powder to be lithiated.

[0043] In some embodiments, the powder to be lithiated includes graphite, hard carbon or amorphous carbon. It is understood that the powder to be lithiated has a special spatial structure, for example, the interlayer structure of graphite can accommodate the embedding of lithium, thereby being lithiated. In addition, the powder to be lithiated is mainly carbon, which has good stability under the reaction conditions of the embodiment of the present application.

[0044] In some embodiments, the molar ratio between the powder to be lithiated and the liquid lithium is 1.2:1-1.5:1. For example, the molar ratio between the powder to be lithiated and the liquid lithium can be 1.2:1, 1.3:1, 1.4:1, 1.5:1 or within the range of any of the above values. It is understandable that the molar number of the powder to be lithiated is greater than that of the liquid lithium, so that the separated liquid lithium can be fully absorbed, thereby improving the recovery rate of lithium. The mass of copper and lithium in the copper-lithium composite belt can be determined. Assuming that all the lithium in the copper-lithium composite belt is separated, the mass of the liquid lithium can be calculated, and then the amount of powder to be lithiated can be determined.

[0045] Step S40, placing the lithiated powder in an acid solution for reaction, and separating a lithium-containing solution;

[0046] The lithium element is active in nature, while the powder to be lithiated is stable. When the lithiated powder is placed in acid, lithium can be dissolved in the acid to achieve lithium leaching. At the same time, the powder to be lithiated itself does not react with the acid and will not dissolve in the acid. Solid-liquid separation can obtain a lithium-containing solution and the powder to be lithiated after delithiation.

[0047] In some embodiments, the concentration of hydrogen ions in the acid solution is 1 mol / L-4 mol / L. For example, the concentration of hydrogen ions in the acid solution can be 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, or in a range composed of any of the above values. The concentration of hydrogen ions will affect the acidity of the acid solution. A sufficient concentration of hydrogen ions can effectively dissolve the lithium in the lithiated powder, while an excessively high concentration of hydrogen ions will cause a violent reaction and increase the risk.

[0048] In some embodiments, the acid solution may be sulfuric acid or hydrochloric acid.

[0049] In some embodiments, the reaction temperature is set to 50°C-95°C, and the stirring speed is 100r / min-300r / min. For example, the reaction temperature can be 50°C, 60°C, 70°C, 80°C, 90°C, 95°C, or within the range of any of the above values. The stirring speed can be 100r / min, 150r / min, 200r / min, 250r / min, 300r / min, or within the range of any of the above values. Properly increasing the reaction temperature can promote the dissolution of lithium. Stirring can promote the dispersion of the lithiated powder in the acid solution, so that the lithiated powder is fully in contact with the acid solution, and the lithium is fully leached into the solution to obtain a lithium-containing solution.

[0050] In some embodiments, the lithium-free powder after the lithium-containing solution is separated is recycled as the powder to be lithiated. The lithium in the lithiated powder enters the solution to form a lithium-containing solution, and the other parts that are insoluble in the acid solution are mainly the original powder to be lithiated. The solid slag obtained after solid-liquid separation can be recycled and reused as the powder to be lithiated. In this way, the utilization rate of the powder to be lithiated is greatly improved, which is conducive to controlling the recycling cost.

[0051] Step S50, adding sodium carbonate to the lithium-containing solution, adjusting the pH value to alkaline, separating the slag, and recovering the lithium carbonate.

[0052] The pH value of the lithium-containing solution is acidic. During the gradual addition of sodium carbonate, carbonate ions react with hydrogen ions and continuously consume hydrogen ions, causing the pH value of the solution to change from neutral to alkaline. After the hydrogen ions are consumed, lithium ions combine with carbonate ions to form lithium carbonate. Since lithium carbonate has a low solubility in water, lithium carbonate precipitation will be generated. After the lithium ions are completely precipitated, the precipitated slag is separated and the lithium carbonate can be recovered.

[0053] In some embodiments, the pH value is adjusted to 9-11, the reaction temperature is set to 50°C-95°C, and the stirring is assisted by 100r / min-300r / min. For example, the pH value can be adjusted to 9, 9.5, 10, 10.5, 11 or within the range of any of the above values. The reaction temperature can be set to 50°C, 60°C, 70°C, 80°C, 90°C, 95°C or within the range of any of the above values. The stirring speed can be 100r / min, 150r / min, 200r / min, 250r / min, 300r / min or within the range of any of the above values. When the pH value is adjusted to a strong alkalinity, the precipitation of lithium ions can be completely promoted. The solubility of lithium carbonate decreases with increasing temperature, so setting a higher reaction temperature can promote the precipitation of lithium ions. Assisted by stirring can also promote the full reaction between carbonate ions and lithium ions and improve precipitation efficiency.

[0054] In this embodiment, the copper-lithium composite tape is placed in an inert liquid, wherein the boiling point of the inert liquid is greater than or equal to 240° C. and the density is greater than or equal to 0.6 g / cm 3The inert liquid does not chemically react with lithium and copper, has a high boiling point, which is above the melting point of lithium, and has a greater density than lithium; the inert liquid is heated to convert the lithium in the copper-lithium composite belt into liquid lithium, which floats to the surface of the inert liquid, and the copper substrate after lithium separation is recovered. Due to the high boiling point and high density of the inert liquid, the lithium in the copper-lithium composite belt is melted and converted into liquid under heating conditions and then floats to the surface, and the copper substrate that has not floated can be separated; the liquid lithium is mixed with the powder to be lithiated to obtain to the lithiated powder, the liquid lithium is absorbed by the powder to be lithiated, and the lithium is embedded in the structure of the powder to be lithiated; the lithiated powder is placed in an acid solution to react, and a lithium-containing solution is separated, and the lithium element in the lithiated powder reacts with the acid solution to form lithium ions dissolved in the acid solution, while the powder to be lithiated is insoluble in the acid solution, thereby transferring the lithium element to the separated lithium-containing solution; sodium carbonate is added to the lithium-containing solution, the pH value is adjusted to alkaline, the slag is separated, and lithium carbonate is recovered. In an alkaline environment, lithium ions combine with carbonate ions to generate lithium carbonate that is recovered. Therefore, the reaction temperature required for the recovery method of the present application is relatively low, which can reduce the risk of thermal runaway and reduce the energy consumption of recovery.

[0055] Reference Figure 2 , Figure 2 This is a schematic diagram of the process of the second embodiment of a copper-lithium composite strip recovery method of the present application. Figure 2 As shown, first, the copper-lithium composite tape is placed in an inert liquid under a protective atmosphere. The inert liquid does not react with metallic lithium, and the inert liquid can use a density of not less than 0.6 g / cm 3 , and an organic solvent with a boiling point of not less than 240°C. Heat the inert liquid to 180°C-220°C to convert the metallic lithium into a liquid state. At the same time, combine ultrasonic vibrations with a frequency of 20kHz-40kHz to allow the liquid metallic lithium to be peeled off from the copper substrate and float to the surface of the liquid. The copper substrate can then be directly recovered. Then separate the upper layer of liquid metallic lithium, and then mix it with a powder that can be gently lithiated, and assist with mechanical stirring. When the metallic lithium is completely reacted, the obtained lithiated material enters the next step. The amount of lithiated powder is 1.2-1.5 times that required for it to absorb all the metallic lithium. Put the lithiated powder into an acid solution with a hydrogen ion concentration of 1mol / L-4mol / L, and leach the lithium element to obtain a lithium-containing solution. The reaction temperature is 50°C-95°C, and is assisted by stirring at 100r / min-300r / min. The acid solution can be sulfuric acid or hydrochloric acid. Filter and separate the delithiated powder and the lithium-containing solution. The delithiated powder is reused. Add soda ash to the lithium-containing solution obtained in the previous step, control the pH value to between 9 and 11, the reaction temperature to between 50° C. and 95° C., and assist with stirring at 100 r / min to 300 r / min. Filter and separate the slag to obtain recovered lithium carbonate.

[0056] The present application scheme is described in detail below with reference to specific embodiments.

[0057] Example 1

[0058] Step 1: Place the copper-lithium composite tape in paraffin oil under a protective atmosphere.

[0059] Step 2: Heat the paraffin oil to 220°C to convert the metallic lithium into liquid. At the same time, combine with ultrasonic vibration with a frequency of 20kHz to make the liquid metallic lithium peel off from the copper substrate and float to the surface of the liquid. Then directly recover the copper substrate.

[0060] Step 3: Separate the upper layer of liquid lithium metal and mix it with graphite powder, and assist with mechanical stirring. When the metal lithium is completely reacted, the obtained lithiated material enters step 4. Wait until the amount of graphite powder is 1.2 times the amount required for it to absorb all the metal lithium.

[0061] Step 4: Put the lithiated powder into a sulfuric acid solution with a hydrogen ion concentration of 4 mol / L to leach lithium elements to obtain a lithium-containing solution. The reaction temperature is 90° C. and the stirring speed is 300 r / min.

[0062] Step 5: Filter and separate the delithiated graphite powder and the lithium-containing solution. The delithiated powder is recycled to step 3.

[0063] Step 6: Add soda ash to the lithium-containing solution obtained in step 5, control the pH value to 10, the reaction temperature to 60° C., and assist with stirring at 300 r / min.

[0064] Step 7: Filter and separate the slag to obtain recovered lithium carbonate.

[0065] Example 2

[0066] Step 1: Place the copper-lithium composite tape in diphenyl ether under a protective atmosphere.

[0067] Step 2: Heat diphenyl ether to 200°C to convert metallic lithium into liquid. At the same time, combine with ultrasonic vibration with a frequency of 30kHz to make the liquid metallic lithium peel off from the copper substrate and float to the surface of the liquid. Then directly recover the copper substrate.

[0068] Step 3: Separate the upper layer of liquid lithium metal and mix it with hard carbon powder, and assist with mechanical stirring. When the metal lithium is completely absorbed repeatedly, the obtained lithiated material enters step 4. Wait until the amount of hard carbon powder is 1.2 times the amount required for it to absorb all the metal lithium.

[0069] Step 4: Put the lithiated powder into a sulfuric acid solution with a hydrogen ion concentration of 4 mol / L to leach lithium elements to obtain a lithium-containing solution. The reaction temperature is 90° C. and the stirring speed is 300 r / min.

[0070] Step 5: Filter and separate the delithiated graphite powder and the lithium-containing solution. The delithiated powder is recycled to step 3.

[0071] Step 6: Add soda ash to the lithium-containing solution obtained in step 5, control the pH value to 10, the reaction temperature to 60° C., and assist with stirring at 300 r / min.

[0072] Step 7: Filter and separate the slag to obtain recovered lithium carbonate.

[0073] Example 3

[0074] Step 1: Place the copper-lithium composite tape in paraffin oil under a protective atmosphere.

[0075] Step 2: Heat the paraffin oil to 200°C to convert the metallic lithium into liquid. At the same time, combine with ultrasonic vibration with a frequency of 30kHz to make the liquid metallic lithium peel off from the copper substrate and float to the surface of the liquid. Then directly recover the copper substrate.

[0076] Step 3: Separate the upper layer of liquid lithium metal and mix it with hard carbon powder, and assist with mechanical stirring. When the metal lithium is completely absorbed repeatedly, the obtained lithiated material enters step 4. Wait until the amount of hard carbon powder is 1.5 times the amount required for it to absorb all the metal lithium.

[0077] Step 4: Put the lithiated powder into a hydrochloric acid solution with a hydrogen ion concentration of 3 mol / L to leach lithium elements to obtain a lithium-containing solution. The reaction temperature is 80° C. and the stirring speed is 300 r / min.

[0078] Step 5: Filter and separate the delithiated graphite powder and the lithium-containing solution. The delithiated powder is recycled to step 3.

[0079] Step 6: Add soda ash to the lithium-containing solution obtained in step 5, control the pH value to 11, the reaction temperature to 60° C., and assist with stirring at 300 r / min.

[0080] Step 7: Filter and separate the slag to obtain recovered lithium carbonate.

[0081] The recovery effects of Examples 1-3 were tested, and the test results shown in Table 1 below were obtained.

[0082] Table 1

[0083] Copper recovery rate Lithium recovery rate Lithium carbonate purity Example 1 99.1％ 99.0％ 99.4％ Example 2 98.6％ 99.5％ 99.3％ Example 3 98.9％ 99.3％ 98.9％

[0084] It can be seen from the above test results that the recycling method of the embodiment of the present application achieves a higher recovery rate under relatively mild reaction conditions, realizes low-energy consumption and low-risk battery material recycling, and has certain application value.

[0085] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for recovering a copper-lithium composite belt, characterized in that: The following steps are involved: The copper-lithium composite tape is placed in an inert liquid, wherein the boiling point of the inert liquid is greater than or equal to 240° C. and the density is greater than or equal to 0.6 g / cm 3 ; Heating the inert liquid to convert lithium in the copper-lithium composite belt into liquid lithium, which floats to the surface of the inert liquid, and recovering the copper substrate after lithium separation; Mixing the liquid lithium with the powder to be lithiated to obtain a lithiated powder; placing the lithiated powder in an acid solution for reaction, and separating a lithium-containing solution; Sodium carbonate is added to the lithium-containing solution to adjust the pH value to alkaline, slag is separated, and lithium carbonate is recovered.

2. The method for recovering the copper-lithium composite belt according to claim 1, characterized in that: The inert liquid includes paraffin oil, diphenyl ether, benzyl benzoate or dibutyl phthalate.

3. The method for recovering the copper-lithium composite belt according to claim 2, characterized in that: The heating temperature of the inert liquid is 180°C-220°C.

4. The method for recovering a copper-lithium composite strip according to any one of claims 1 to 3, characterized in that: The step of heating the inert liquid to convert lithium in the copper-lithium composite belt into liquid lithium and float it to the surface of the inert liquid is further supplemented by ultrasonic treatment, and the frequency of the ultrasonic treatment is 20kHz-40kHz.

5. The method for recovering the copper-lithium composite belt according to claim 1, characterized in that: The powder to be lithiated includes graphite, hard carbon or amorphous carbon.

6. The method for recovering the copper-lithium composite belt according to claim 5, characterized in that: The molar ratio between the powder to be lithiated and the liquid lithium is 1.2:1-1.5:

1.

7. The method for recovering the copper-lithium composite belt according to claim 1, characterized in that: The concentration of hydrogen ions in the acid solution is 1 mol / L-4 mol / L.

8. The method for recovering the copper-lithium composite belt according to claim 1, characterized in that: In the step of placing the lithiated powder in an acid solution for reaction, the reaction temperature is set at 50° C.-95° C. and the stirring speed is set at 100 r / min-300 r / min.

9. The method for recovering a copper-lithium composite strip according to claim 1, wherein: In the step of adding sodium carbonate to the lithium-containing solution, adjusting the pH value to alkaline, separating the slag, and recovering lithium carbonate, the pH value is adjusted to 9-11, the reaction temperature is set to 50°C-95°C, and the stirring is assisted by 100r / min-300r / min.

10. The method for recovering a copper-lithium composite strip according to any one of claims 5 to 9, characterized in that: The lithium-free powder after separation of the lithium-containing solution is recycled as the powder to be lithiated.

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