Device for recycling lithium composite copper foil composite belt and lithium battery recycling system

Abstract

The utility model provides a device for recycling a lithium composite copper foil composite belt and a lithium battery recycling system, and relates to the technical field of battery recycling. The lithium composite copper foil composite belt sequentially passes through a lithiation area, a first cleaning area, a first drying area and a nitration area through a guide roller, lithium is dissolved in the lithiation area to obtain a composite copper foil, copper is dissolved through the nitration area after cleaning and drying, and the diaphragm is recycled. The device provided by the utility model is convenient to operate, simple and controllable in reaction, and capable of realizing industrial recovery of metal lithium, diaphragm layers and copper metal.

Description

Technical Field

[0001] The utility model relates to the technical field of battery recycling, in particular to a device for recycling lithium composite copper foil composite strips and a lithium battery recycling system. Background Art

[0002] Lithium batteries are now widely used in new energy vehicles. Faced with the issue of spontaneous combustion in new energy vehicles, many lithium battery manufacturers are using composite copper foil as the battery current collector. This improves battery safety, energy density, and compatibility while also reducing costs. This type of current collector, combined with metallic lithium, is called a lithium-copper composite ribbon, which opens a new direction for downstream lithium-solid-state batteries. The recycling of the metallic lithium and rolled PP film from discarded lithium-copper composite ribbons is crucial.

[0003] Currently, there is no device specifically designed for recycling lithium-copper composite strips, and existing methods for recycling lithium-copper composite strips generally have problems such as high energy consumption and low process efficiency.

[0004] In view of this, the present utility model is proposed. Utility Model Content

[0005] The purpose of the utility model includes providing a device for recycling lithium-copper composite foil and composite strip, aiming to provide a device that is easy to operate and used for efficiently recycling lithium-copper composite strip.

[0006] The embodiment of the present utility model can be implemented as follows:

[0007] In a first aspect, the utility model provides a device for recycling lithium-composite copper foil composite strips, comprising a lithiation zone, a first cleaning zone, a first drying zone, and a nitration zone arranged in sequence, wherein the lithiation zone, the first cleaning zone, the first drying zone, and the nitration zone are all provided with guide rollers, so that the lithium-composite copper foil composite strips pass through the lithiation zone, the first cleaning zone, the first drying zone, and the nitration zone in sequence through the guide rollers;

[0008] A first open reactor for containing a reaction solution dissolving lithium is provided in the lithiation zone, and the guide roller is located in the first open reactor;

[0009] The first cleaning area is provided with a cleaning container for containing a cleaning solvent, and the guide roller is located in the cleaning container;

[0010] The first drying zone is provided with a drying box, and the guide roller is located in the drying box;

[0011] A second open reactor for containing a reaction solution containing nitric acid is provided in the nitrification zone, and the guide roller is located in the second open reactor.

[0012] In an optional embodiment, a plurality of tension guide rollers are provided in both the first open reactor and the second open reactor.

[0013] In an optional embodiment, in the lithiation zone, a first spray device for spraying downward is provided above the plurality of tension guide rollers, and a second spray device for spraying upward is provided below the tension guide rollers, and the reaction solution is sprayed out using the first spray device and the second spray device.

[0014] In an optional embodiment, the first spray device and the second spray device each include a plurality of spray heads.

[0015] In an optional embodiment, a first gas extraction device is provided at the top of the lithiation zone, and a second gas extraction device is provided at the top of the nitration zone to collect the gas generated by the reaction.

[0016] In an optional embodiment, the first open reactor is a collecting tank with a sloped bottom.

[0017] In an optional embodiment, a heating device is further provided on the nitrification zone.

[0018] In an optional embodiment, a second cleaning zone is provided after the nitrification zone. The second cleaning zone is provided with a cleaning container for containing a cleaning solvent, and a guide roller is provided in the cleaning container.

[0019] In an optional embodiment, a second drying zone is further provided after the second cleaning zone, and the second drying zone is provided with a drying box, and a guide roller is provided in the drying box;

[0020] A reel-off shaft is provided at one end of the lithiation zone, and a reel-off shaft is provided at one end of the second drying zone.

[0021] In a second aspect, the present invention provides a lithium battery recycling system, comprising the device for recycling lithium-composite copper foil and composite strip according to any one of the aforementioned embodiments.

[0022] The beneficial effects of the apparatus and lithium battery recycling system provided by the present invention include: guide rollers guide the lithium-copper foil composite strip through a lithiation zone, a first cleaning zone, a first drying zone, and a nitration zone. The lithium is dissolved in the lithiation zone to produce composite copper foil. After cleaning and drying, the strip passes through the nitration zone to dissolve copper and recover the separator. The apparatus is easy to operate, features simple and controllable reactions, and can achieve industrial recovery of metallic lithium, separator layers, and copper. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 A schematic diagram of the structure of the lithium-copper composite foil composite strip processed by an embodiment of the present utility model;

[0025] Figure 2 A distribution diagram of each area in the method provided by an embodiment of the present utility model;

[0026] Figure 3 A flow chart of the device provided in accordance with an embodiment of the present invention;

[0027] Figure 4 A diagram of a device for a lithiation zone provided in an embodiment of the present invention;

[0028] Figure 5 This is a diagram of the device of the nitrification zone provided in an embodiment of the present utility model.

[0029] Icon: 10-lithium composite copper foil composite tape; 101-first metal lithium layer; 102-first copper layer; 103-diaphragm layer; 104-second copper layer; 105-second metal lithium layer; 106-composite copper foil;

[0030] 100 - Device for recovering lithium-copper-clad composite strip; 110 - Lithiation zone; 120 - First cleaning zone; 130 - First drying zone; 140 - Nitration zone; 150 - Second cleaning zone; 160 - Second drying zone; 171 - Guide roller; 111 - First open reactor; 121 - First cleaning container; 131 - First drying oven; 141 - Second open reactor; 151 - Second cleaning container; 161 - Second drying oven;

[0031] 001-unwinding shaft; 002-first air extraction device; 003-rewinding shaft; 004-first spray device; 005-second spray device; 006-tension guide roller; 007-second air extraction device; 008-heating device. DETAILED DESCRIPTION

[0032] To make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments used, where the manufacturer is not specified, are all conventional products that can be purchased commercially.

[0033] like Figure 1 As shown, the lithium composite copper foil composite strip 10 processed by the embodiment of the present invention is a common material of existing lithium batteries, including a first metal lithium layer 101, a first copper layer 102, a diaphragm layer 103, a second copper layer 104 and a second metal lithium layer 105 arranged in sequence, and the first copper layer 102, the diaphragm layer 103 and the second copper layer 104 form a composite copper foil 106.

[0034] In some embodiments, the first metal lithium layer 101 and the second metal lithium layer 105 can be ultra-thin metal lithium, and the thickness of the first metal lithium layer 101 and the second metal lithium layer 105 are both 5μm-100μm. The thickness of the first metal lithium layer 101 and the second metal lithium layer 105 can be the same or different.

[0035] In some embodiments, the first copper layer 102 and the second copper layer 104 are formed of copper foil. The thickness of the first copper layer 102 and the second copper layer 104 are both 1 μm-3 μm. The thickness of the first copper layer 102 and the second copper layer 104 can be the same or different.

[0036] In some embodiments, the diaphragm layer 103 may be at least one of a PP film (polypropylene film) and a PET film (polyethylene terephthalate film), preferably a PP film. The thickness of the diaphragm layer 103 is 1 μm-10 μm.

[0037] like Figure 2 An embodiment of the present invention provides a device 100 for recycling lithium-composite copper foil composite strips, comprising a lithiation zone 110, a first cleaning zone 120, a first drying zone 130 and a nitrification zone 140 arranged in sequence. The lithiation zone 110, the first cleaning zone 120, the first drying zone 130 and the nitrification zone 140 are all provided with guide rollers 171, so that the lithium-composite copper foil composite strips pass through the lithiation zone 110, the first cleaning zone 120, the first drying zone 130 and the nitrification zone 140 in sequence through the guide rollers 171, and are transported by the guide rollers 171, which is convenient for control, easy to operate, and can improve work efficiency.

[0038] A first open reactor 111 for holding a reaction solution that dissolves lithium is provided in the lithiation zone 110. The guide roller 171 is located in the first open reactor 111. A solution that can dissolve lithium is placed in the first open reactor 111 to cause the outer first metal lithium layer 101 and the second metal lithium layer 105 to fall off, thereby obtaining a composite copper foil.

[0039] The first cleaning zone 120 is provided with a first cleaning container 121 for containing a cleaning solvent. The guide roller 171 is located in the first cleaning container 121. In the first cleaning zone 120, the composite copper foil is cleaned with the solvent to remove the unreacted reagent remaining on the surface.

[0040] The first drying zone 130 is provided with a first drying box 131 . The guide roller 171 is located in the first drying box 131 . The first drying box 131 removes the solvent on the surface of the composite copper foil by heating.

[0041] A second open reactor 141 for holding a reaction solution containing nitric acid is provided in the nitrification zone 140. The guide roller 171 is located in the second open reactor 141. The second copper layer 104 and the first copper layer 102 in the composite copper foil in the nitrification zone 140 are dissolved, and the middle diaphragm layer 103 is recovered and enters the subsequent second cleaning zone 150 and second drying zone 160.

[0042] The structure of the second cleaning zone 150 is similar to that of the first cleaning zone 120. It is equipped with a second cleaning container 151 for holding the cleaning solvent, and a guide roller 171 is installed within the second cleaning container 151. The structure of the second drying zone 160 is similar to that of the first drying zone 130. It is equipped with a second drying box 161, and a guide roller 171 is installed within the second drying box 161. The strip is conveyed by the guide roller 171, passing through the lithiation zone 110, the first cleaning zone 120, the first drying zone 130, the nitration zone 140, the second cleaning zone 150, and the second drying zone 160 in sequence.

[0043] In some embodiments, a heating device 008 is further provided on the nitrification zone 140 to promote the dissolution of copper by heating the second open reactor 141 .

[0044] In some embodiments, a first gas extraction device 002 is provided at the top of the lithiation zone 110 to collect generated gases, such as hydrogen, which are burned and used to heat the nitration zone 140. A second gas extraction device 007 is provided at the top of the nitration zone 140 to collect gases generated by the reaction, such as nitric oxide.

[0045] In some embodiments, the first open reactor 111 may be a collecting tank with a sloped bottom, such as a Y-shaped collector, to facilitate material output.

[0046] Please combine Figure 2 、 Figure 3 and Figure 4 A reel 001 is installed at one end of the lithiation zone 110, and a reel 003 is installed at the other end. A reel 003 is installed at one end of the second drying zone 160. Multiple tension guide rollers 006 are installed in the first open reactor 111 and the second open reactor 141. The reel 001, reel 003, and tension guide rollers 006 are located in different positions to facilitate the transfer of materials into and out of different areas.

[0047] In some embodiments, in the lithiation zone 110, a first spray device 004 for spraying downward is provided above the plurality of tension guide rollers 006, and a second spray device 005 for spraying upward is provided below the tension guide rollers 006. The reaction solution is sprayed out using the first spray device 004 and the second spray device 005 to uniformly contact the strip.

[0048] Furthermore, the first spray device and the second spray device each include a plurality of nozzles. By regulating the nozzle flow rate and the size of the droplets, the reaction rate can be slowed down to prevent a violent reaction from causing a safety accident.

[0049] The following is a more detailed description of the working principles of each zone in combination with the method of recycling lithium composite copper foil composite strip:

[0050] Please combine Figure 5 The present invention provides a method for recycling lithium-copper composite foil and composite strip, comprising the following steps:

[0051] S1, lithium dissolution in the lithiation zone

[0052] The lithium composite copper foil composite tape is reacted in an organic solution containing carboxyl or hydroxyl groups (such as an organic weak acid solution) to dissolve the first metal lithium layer and the second metal lithium layer, thereby recovering the lithium.

[0053] In some embodiments, the organic solution is a mixture of an organic acid, an organic alcohol solvent, and water, with the organic alcohol acting as a cooling agent. The lithium-copper foil composite tape reacts in the organic solution to produce a weak acid lithium salt solution. This solution is then purified through heating, evaporation, and recrystallization, yielding a purified lithium salt for use in the pharmaceutical raw materials industry. Specifically, organolithium reagents are essential and important reagents in metal-organic synthesis and are the most important reagents in alkali metal organic compounds. Furthermore, organolithium compounds can be used to treat conditions such as depression and epilepsy.

[0054] Furthermore, the organic acid is selected from at least one of oxalic acid, acetic acid, tartaric acid and citric acid, and the organic acid can be any one or more of the above. The organic alcohol solvent can be ethanol, and the volume ratio of the organic alcohol solvent to water is 1: (0.5-1.5), such as 1: 0.5, 1: 1.0, 1: 1.5, etc. Different organic acids have different solubilities, and the concentrations of the corresponding organic acid solutions will also be different. The concentration of the organic acid is close to its maximum solubility in water and ethanol. For example, the solubility of oxalic acid in water is 150 g / L, and the solubility in ethanol is 400 g / L. The organic solution is prepared under the conditions of 5 L of pure water and 5 L of ethanol to make the concentration of the organic acid as large as possible, thereby increasing the concentration of the weak acid lithium salt solution.

[0055] The waste lithium composite copper foil composite tape is threaded into the organic solution, and the metallic lithium reacts with the organic acid solution to generate relevant organic salts. The chemical reaction equation is:

[0056] 2R-COOH+2Li=2R-COOLi+H2↑;

[0057] 2R-OH+2Li=2R-OLi+H2↑;

[0058] 2H2O+2Li=2LiOH+H2↑;

[0059] 2C2H5OH+2Li=2C2H4OLi+H2↑.

[0060] The following is the reaction principle of some organic acid solutions:

[0061] Oxalic acid solution: Oxalic acid is solid and is added with a small amount of water to produce an oxalic acid solution. The resulting product, lithium oxalate, is slightly soluble in water at a solubility-water ratio of 8:100 and easily separates from water.

[0062] Oxalic acid: 2C2H2O4+2Li=2C2HO4Li+H2↑;

[0063] 2H2O+2Li=2LiOH+H2↑;

[0064] 2C2H5OH+2Li=2C2H4OLi+H2↑.

[0065] Acetic acid solution: Acetic acid is liquid, and lithium acetate is obtained after the reaction. Recrystallization can obtain purified lithium acetate.

[0066] Acetic acid: 2CH3COOH+2Li=2CH3COOLi+H2↑;

[0067] 2H2O+2Li=2LiOH+H2↑;

[0068] 2C2H5OH+2Li=2C2H4OLi+H2↑.

[0069] Tartaric acid solution: Tartaric acid is soluble in water and is often used as a raw material in the pharmaceutical industry. Lithium tartrate usually exists as a dihydrate. In addition, the higher the temperature, the lower the solubility (42g / 0℃). Lithium tartrate crystals can be obtained by controlling the reaction temperature.

[0070] Tartaric acid: 2C4H6O6+2Li=2C4H5O6+H2↑;

[0071] 2H2O+2Li=2LiOH+H2↑;

[0072] 2C2H5OH+2Li=2C2H4OLi+H2↑.

[0073] Citric acid solution: Citric acid is a colorless crystal that is easily soluble in water. Lithium citrate usually exists as a tetrahydrate and loses its water of crystallization when heated to 105°C.

[0074] Citric acid: 2C6H8O7+2Li=2C6H7O7Li+H2↑;

[0075] 2H2O+2Li=2LiOH+H2↑;

[0076] Ethanol: 2C2H5OH+2Li=2C2H4OLi+H2↑.

[0077] like Figure 5 As shown, the lithium dissolving step is carried out in the lithiation zone, and the hydrogen produced by the reaction with the organic acid is collected and used to supply heat to the nitration zone.

[0078] Figure 2 and Figure 3 The lithiation zone is shown in Figure 1. A first extraction device 002 is installed at the top of the lithiation zone. This device includes a pump and a pressure tank to extract the hydrogen produced by the reaction. A wet filter cloth is used at the tail end of the first extraction device 002 to filter out organic acids, alcohols, and water carried by the hydrogen. Due to its low density, hydrogen can be collected using a drainage method.

[0079] Preferably, the reaction is conducted in the lithiation zone using a collection trough with a sloped bottom, such as a Y-shaped trough, where the droplets are collected along the slope. However, the shape of the collection device is not limited to a Y-shape; the slope is the primary controlling factor. Other sloped shapes can be used to facilitate droplet collection.

[0080] In some embodiments, a unwinding shaft 001 is provided at one end of the lithiation zone, and a winding shaft 003 is provided at the other end (at one end of the second drying zone), and a plurality of tension guide rollers 006 are provided in the reaction tank of the lithiation zone, so that the lithium composite copper foil composite strip or composite copper foil is transmitted in sequence through the unwinding shaft 001, a plurality of tension guide rollers 006 and the winding shaft 003.

[0081] The lithiation zone uses a weak organic acid to react with metallic lithium. This reaction is intense, requiring controlled organic solution volume and reaction time. The organic solution can be sprayed using a fine spray, and the reaction time can be automatically adjusted based on feedback from the amount of hydrogen collected. For example, the amount of hydrogen produced can be calculated based on the amount of lithium before the reaction, and the reaction time can be adjusted based on the amount of hydrogen collected. The reaction ends when the amount of hydrogen collected reaches the theoretical amount. During the reaction, multiple tension guide rollers 006 can be used to increase the reaction area. The hydrogen produced by the reaction is collected through a drainage method and then applied to the dilute nitric acid solution in the copper reaction zone to increase the reaction efficiency of the copperization zone.

[0082] In some embodiments, in the lithiation zone, a first spray device 004 for spraying downward is provided above the plurality of tension guide rollers 006, and a second spray device 005 for spraying upward is provided below the tension guide rollers 006. The organic solution is sprayed out by the first spray device 004 and the second spray device 005, and the organic solution is caused to submerge the plurality of tension guide rollers. The first spray device 004 and the second spray device 005 each include a plurality of nozzles, and the spray flow rate of each nozzle is greater than 4.2×10 -3mL / min, the droplet diameter is 3μm-15μm. It can be calculated that each nozzle can spray at least 5 billion droplets per second. By adjusting the flow rate and droplet size, the purpose is to slow the reaction rate and prevent violent reactions from causing safety accidents.

[0083] Specifically, the high-pressure spray has different compositional characteristics. The lithiation spray is graded with varying molar amounts of organic acid, gradually increasing the organic acid content. The maximum molar concentration of the organic acid in the corresponding water-ethanol mixture is determined by the spray nozzle. The number of nozzles and flow rate can be adjusted based on parameters such as the thickness of the waste strip to be treated and the area to be treated, controlling the intensity of the reaction and achieving the recovery of metallic lithium into organic lithium.

[0084] In some embodiments, the initial operating speed is controlled to be 0.05 m / min-0.3 m / min (e.g., 0.05 m / min, 0.1 m / min, 0.2 m / min, 0.3 m / min, etc.). The spray devices above and below the multiple tension guide rollers 006 are filled with a weak organic acid mixture or an organic compound with a hydroxyl group, and the reaction formula is as follows:

[0085] 2R-COOH+2Li=2R-COOLi+H2↑;

[0086] 2R-OH+2Li=2R-OLi+H2↑;

[0087] The embodiment of the utility model can achieve 100% recovery of metallic lithium and obtain a high-value organic acid lithium solution.

[0088] The degree of lithium metal digestion is determined based on the amount of hydrogen collected, thereby controlling the unwinding speed. The unwinding rate is calculated as follows:

[0089] y = -0.067x + 2;

[0090] Where y represents the operating speed in m / min, and x represents the hydrogen production volume in L. The calculation ignores the units and only performs numerical operations. The formula for calculating the unwinding rate is not limited to the above formula.

[0091] S2. Cleaning and drying

[0092] like Figure 5 As shown, the lithium composite copper foil composite strip passes through the lithiation zone via a guide roller, and then passes through the first cleaning zone and the drying zone. It is cleaned with a solvent in the first cleaning zone and then enters the drying zone for drying to obtain a composite copper foil.

[0093] In some embodiments, the solvent used in the cleaning process is selected from at least one of ethanol, methanol, and water (e.g., purified water). The cleaning solvent may be any one or more of the above. In a preferred embodiment, the solvent used in the cleaning process is ethanol with a mass fraction of 50%-75%. The ethanol aqueous solution in this concentration range is readily available and inexpensive, and can clean the organic acid and a small amount of unreacted lithium on the surface, leaving the surface clean and smooth.

[0094] In some embodiments, the drying oven can be operated in a forced air drying oven, which can continuously process the material from the cleaning area. The drying temperature is controlled to be 30°C-80°C, which can better remove solvents such as ethanol.

[0095] S3, Dissolved copper in nitrification zone

[0096] The composite copper foil output from the drying area enters the nitrification area and reacts with the nitric acid mixture to dissolve the first and second copper layers on the surface while recovering the diaphragm layer.

[0097] In some embodiments, the nitric oxide obtained by the reaction in the nitric acid mixture can be collected and reacted with an oxygen-containing atmosphere and water in an oxidation zone to obtain a nitric acid solution, and the nitric acid solution obtained by the reaction can be recycled to prepare the nitric acid mixture.

[0098] In some embodiments, the nitric acid mixture may be dilute nitric acid with a mass fraction of 20%-50%, and the concentration of the dilute nitric acid may be 20%, 30%, 40%, 50%, etc. The chemical reaction equation is as follows:

[0099] 3Cu+8HNO3(dilute)=3Cu(NO3)2+2NO↑+4H2O;

[0100] like Figure 2 and Figure 4 As shown, a reel 001 is provided at one end of the nitrification zone, and a reel 003 is provided at the other end (at one end of the second drying zone). Multiple tension guide rollers 006 are provided within the reaction vessel of the nitrification zone, so that the composite copper foil is sequentially transported through the reel 001, the multiple tension guide rollers 006, and the reel 003. The number of tension guide rollers 006 in the nitrification zone is not limited. During operation, the guide rollers are submerged in the dilute nitric acid solution to increase the reaction area and the reaction rate.

[0101] Furthermore, due to the toxicity of nitric oxide, a second exhaust device 007 is provided at the top of the nitrification zone to collect the nitric oxide produced by the reaction. The nitric oxide collected in the nitrification zone is reacted with water in an oxygen-containing atmosphere to produce a nitric acid solution, which is then circulated to the nitrification zone. The chemical reaction equation is as follows:

[0102] 4NO+3O2+2H2O=4HNO3.

[0103] In some embodiments, a heating device is provided in the nitration zone. The heating device utilizes hydrogen collected in the lithiation zone to generate heat, thereby accelerating the nitration reaction. The heating device may be located below the reaction tank in the nitration zone, but is not limited thereto.

[0104] Furthermore, the diaphragm layer (PP / PET film) output from the nitrification zone can be passed through the second cleaning zone (i.e. Figure 5 The product enters the cleaning area after the intermediate nitrification area to remove unreacted ions on the surface, and then enters the winding area to wind the finished product.

[0105] It should be noted that the embodiment of the present invention can realize roll-to-roll processing of waste lithium-composite copper foil composite strips, which improves the efficiency of the current process by at least 80%, achieves 100% recycling of metallic lithium and PP film, and the copper recovery rate can reach more than 95%. In particular, the recycled roll PP film can be used as a strip support film to realize waste utilization and protect the environment and resources.

[0106] In addition, the method provided by the embodiment of the present invention can be applied to the recycling of pure lithium strips, ultra-thin lithium strips, ultra-thin lithium-copper composite strips, lithium alloy strips and other strips. It can also be applied to the recovery of copper metal from materials such as composite copper foil below 10μm, electrolytic copper foil, and microporous copper foil. It has a high degree of industrialization and can improve recycling efficiency.

[0107] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0108] It should be noted that the following embodiments all provide a method for recycling lithium composite copper foil composite strips, such as Figure 5 As shown, the waste lithium composite copper foil composite tape is subjected to lithium and organic acid reaction in the lithiation zone, followed by continuous cleaning and drying, and then placed in the nitration zone to complete the copper nitration reaction, and finally a roll of PP / PET film is obtained for recovery.

[0109] The organic acid used in the lithiation zone of Example 1 and the comparative example is oxalic acid.

[0110] Example 1 - Recycling of lithium-copper composite foil and composite strip

[0111] (1) Provide a waste lithium-copper composite tape to be processed. The copper foil of the lithium-composite copper foil composite tape (i.e., the first copper layer 102 and the second copper layer 104) are both pure copper (prepared by magnetron sputtering process), with a copper layer thickness of 1.5 μm and a width of 200 mm; the waste lithium (i.e., the first metal lithium layer 101 and the second metal lithium layer 105) is 20 μm thick and 180 mm wide; the diaphragm layer 103 is a PP film with a thickness of 3 μm and a width of 200 μm. The composite tape is 50 m long, and the estimated amount of metal lithium to be processed is 192.24 g. The lithium-composite copper foil composite tape is threaded with a threading tension of 10 N.

[0112] (2) The program is opened, the guide roller begins to rotate, and the initial rotation speed is set to 0.08 m / min. The waste composite strip to be processed enters the lithiation zone. The 19 nozzle devices in the lithiation zone are opened. The single spray flow rate is shown in the table below. The high-pressure micro-mist spray nozzle can produce 5 billion droplets per second, and the droplet diameter is 3 to 15 μm. The content of each nozzle device is as follows, a total of 19 nozzle devices and 76 nozzles.

[0113] Table 1: Nozzle organic acid parameter diagram

[0114]

[0115] The waste composite belt undergoes a lithiation reaction. Metallic lithium follows the reaction steps of oxalic acid, water, and ethanol. 2 mol of metallic lithium is required to generate 1 mol of hydrogen. The operating speed is 0.08 m / min. The reaction product is a mixture of lithium oxalate and lithium hydroxide. A Y-type collector is used in the lithiation zone to purify and separate the lithium oxalate. The spray flow rate and lithium consumption are shown in the following table:

[0116] Table 2: Spray flow rate and lithium consumption

[0117]

[0118]

[0119] This time, 19 nozzle devices were selected, with a total nozzle flow rate of 76.73 ml / min and a consumption of 0.3278 g / min of metallic lithium. Theoretically, it takes 586 minutes for the metallic lithium to completely react to generate organic acid lithium for recovery.

[0120] After the lithiation reaction is completed, a composite copper foil strip is obtained, and a small amount of metallic lithium, oxalic acid, lithium oxalate and other compounds may exist on the surface.

[0121] The composite copper foil strip enters the cleaning area, where the cleaning solution is an ethanol solution. The main component is ethanol, with a mass fraction of 60%. This solution can dissolve 99% of the above mixture and facilitate drying. At this stage, the surface of the strip appears orange or a similar color when observed with the naked eye.

[0122] The cleaned composite copper foil enters the blast drying oven and then the nitrification zone. The main reaction equation is as follows: 3Cu + 8HNO3 (dilute) = 3Cu(NO3)2 + 2NO↑ + 4H2O;

[0123] The nitration reaction tank contains several tensioned guide rollers, which are submerged in a dilute nitric acid solution. The guide rollers are made of alkali-resistant material. The primary component of the nitration reaction tank is dilute nitric acid, with a mass fraction of 35%. The remaining component is purified water.

[0124] Since nitric oxide is toxic, a powerful exhaust device is arranged above the nitrification area, and a solution containing air and water is sent into it through a pipe to generate dilute nitric acid, which is then circulated and applied to the nitrification tank.

[0125] The strip from the nitrification zone is cleaned and dried to obtain PP / PET film.

[0126] Testing revealed no metallic lithium on the treated PP film rolls, with a clean surface and high transparency, achieving 100% transmittance, and virtually no metallic copper residue. Theoretically, the complete reaction of metallic lithium to form organic lithium acid is expected to take no more than 586 minutes. The amount of lithium oxalate recovered from the lithium-copper foil and tape waste is no more than 27.7 mol, with a concentration of no more than 0.62 mol / L. Testing revealed that the PP film is 3 μm thick, 200 mm wide, and 50 m long.

[0127] Comparative Example 1

[0128] (1) Provide waste lithium-copper composite tape to be processed. The copper foil of the lithium-composite copper foil composite tape is a composite copper foil with a thickness of 6 μm and a width of 200 mm. The waste lithium is 20 μm thick and 180 mm wide, with lithium on both sides. The separator layer 103 is a PP film with a thickness of 3 μm and a width of 200 μm. The composite tape is 50 m long, and the estimated amount of metallic lithium to be processed is 192.24 g. The lithium-composite copper foil composite tape is threaded with a threading tension of 10 N.

[0129] (2) The program is opened, the guide roller begins to rotate, and the initial rotation speed is set to 0.3 / min. The waste composite strip to be processed enters the lithiation zone. The 31 nozzle devices in the lithiation zone are opened, and the high-pressure micro-mist spray nozzle can produce 5 billion droplets per second, with a droplet diameter of 3 to 15 μm. The content of each nozzle device is as follows: a total of 31 nozzle devices and 124 nozzles. The nozzle liquid is 1.6 mol oxalic acid dissolved in 5L water and 5L ethanol solution, with a concentration of 1.6 mol / L. The spray reacts violently with metallic lithium, which is highly dangerous. A large amount of heat is released, causing the PP film to deform at high temperature and cannot be recycled.

[0130] In Comparative Example 1, the organic acid content in each nozzle is consistent and large, resulting in a high risk factor. The embodiment of the utility model controls the organic acid content in the nozzle to gradually increase, control the reaction rate, slow down the heat release, and reduce the risk.

[0131] Comparative Example 2

[0132] (1) Provide waste lithium-copper composite tape to be processed. The copper foil of the lithium-copper composite tape is a composite copper foil with a thickness of 6 μm and a width of 200 mm. The waste lithium is 20 μm thick and 180 mm wide, and lithium is present on both sides. The separator layer 103 is a PP film with a thickness of 3 μm and a width of 200 μm. The composite tape is 50 m long, and the estimated amount of metallic lithium to be processed is 192.24 g. The lithium-copper composite tape is threaded with a threading tension of 10 N.

[0133] (2) The program is opened, the guide roller begins to rotate, and the initial rotation speed is set to 0.3 / min. The waste composite strip to be processed enters the lithiation zone. The 31 spray nozzle devices in the lithiation zone are opened. The single spray flow rate is shown in Table 3. The high-pressure micro-mist spray nozzle can produce 5 billion droplets per second, and the droplet diameter is 3-15 μm. The content of each nozzle device is as follows: a total of 31 nozzle devices and 124 nozzles. The nozzle liquid is a mixed solution of 5L water and 5L ethanol, and the organic acid concentration is 0mol / L. The water reacts with the waste metal lithium to obtain a maximum of 27.7mol of lithium hydroxide and 0mol of organic acid lithium. The task of recovering high-value organic acid lithium is not completed, but the PP / PET film recovery can be completed.

[0134] Table 3: Nozzle organic acid parameter diagram

[0135]

[0136]

[0137] It can be seen from Comparative Example 2 that the recovery of high-value organic acid lithium cannot be achieved without adding organic acid treatment.

[0138] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A device for recycling lithium composite copper foil composite strips, characterized in that: The method comprises a lithiation zone, a first cleaning zone, a first drying zone and a nitration zone arranged in sequence, wherein the lithiation zone, the first cleaning zone, the first drying zone and the nitration zone are all provided with guide rollers, so that the lithium composite copper foil composite strip passes through the lithiation zone, the first cleaning zone, the first drying zone and the nitration zone in sequence through the guide rollers; A first open reactor for containing a reaction solution dissolving lithium is provided in the lithiation zone, and the guide roller is located in the first open reactor; The first cleaning area is provided with a cleaning container for containing a cleaning solvent, and the guide roller is located in the cleaning container; The first drying zone is provided with a drying box, and the guide roller is located in the drying box; A second open reactor for containing a reaction solution containing nitric acid is provided in the nitrification zone, and the guide roller is located in the second open reactor.

2. The device for recycling lithium composite copper foil composite strip according to claim 1, characterized in that: A plurality of tension guide rollers are provided in both the first open reactor and the second open reactor.

3. The device for recycling lithium composite copper foil composite strip according to claim 2, characterized in that: In the lithiation zone, a first spray device for spraying downward is provided above the plurality of tension guide rollers, and a second spray device for spraying upward is provided below the tension guide rollers. The reaction solution is sprayed out by using the first spray device and the second spray device.

4. The device for recycling lithium composite copper foil composite strip according to claim 3, characterized in that: The first spray device and the second spray device each include a plurality of spray heads.

5. The device for recycling lithium composite copper foil composite strip according to claim 1, characterized in that: A first gas extraction device is provided on the top of the lithiation zone, and a second gas extraction device is provided on the top of the nitration zone to collect the gas generated by the reaction.

6. The device for recycling lithium composite copper foil composite strip according to claim 1, characterized in that: The first open reactor is a collecting tank with a sloped bottom.

7. The device for recycling lithium composite copper foil composite strip according to claim 1, characterized in that: A heating device is also provided on the nitrification zone.

8. The device for recycling lithium composite copper foil composite strip according to claim 1, characterized in that: A second cleaning zone is provided after the nitrification zone. The second cleaning zone is provided with a cleaning container for containing a cleaning solvent. A guide roller is provided in the cleaning container.

9. The device for recycling lithium composite copper foil composite strip according to claim 8, characterized in that: A second drying zone is provided after the second cleaning zone, wherein the second drying zone is provided with a drying box, and a guide roller is provided in the drying box; A reel is provided at one end of the lithiation zone, and a reel is provided at one end of the second drying zone.

10. A lithium battery recycling system, characterized in that: A device for recycling lithium-composite copper foil and composite strip comprising the device described in any one of claims 1 to 9.

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