An electrochemical delithiation device and method for recycling lithium elements in black powder of retired lithium ion batteries

Abstract

The present application belongs to the technical field of lithium battery material recycling and electrochemical delithiation, and relates to an electrochemical delithiation device and method for recycling lithium elements in black powder of retired lithium ion batteries, wherein the device is an integrated electrochemical reaction delithiation system: a movable anode pole piece made of retired black powder material can continuously move under the drive of an electric unwinding machine; and a cathode pole piece is fixed on at least one side of the movable anode pole piece. When the power is turned on, lithium in the retired black powder material in the anode is removed into the electrolyte. The movable anode pole piece delithiated by the electrochemical delithiation device then enters a downstream cleaning mechanism to remove the residual lithium ions on the surface. The method replaces the cathode hydrogen evolution reaction in the conventional system with an oxygen reduction reaction with a more positive electrode potential, achieving low-energy electrochemical delithiation. Compared with the prior art, the electrochemical delithiation device can realize large-batch, low-energy and continuous processing of the retired black powder.

Description

Technical Field

[0001] This invention relates to the field of lithium battery material recycling and electrochemical delithiation technology, specifically to an electrochemical delithiation device and method for recovering lithium from retired lithium-ion battery black powder. Background Technology

[0002] Over the past two decades, lithium-ion battery (LIB) technology has made rapid progress, and its applications have deeply penetrated key areas such as electric vehicles, portable electronic devices, and large-scale energy storage systems. The importance of lithium resources is becoming increasingly prominent.

[0003] However, the natural occurrence of lithium resources (mainly relying on lithium ore and brine from salt lakes) faces supply pressure and environmental challenges. At the same time, with the explosive growth of the lithium battery industry, a large amount of waste LIBs has been generated. These waste batteries contain considerable lithium resources (for example, the lithium content in the cathode material of ternary batteries can reach ~7 wt%). Efficiently recycling and utilizing the lithium in these "urban mines" can not only alleviate the pressure on primary resources and significantly improve the sustainability of resource utilization, but also effectively reduce the environmental risks associated with solid waste disposal. This is of great significance for reducing resource consumption and environmental pollution, promoting sustainable development, and reducing carbon emissions.

[0004] Currently, several technical routes have been proposed and patented for lithium recovery from cathode materials (such as lithium cobalt oxide (LCO), ternary materials NCM / NCA, and lithium iron phosphate (LFP)) in waste lithium-ion batteries. These include hydrometallurgical processes based on sulfuric acid / hydrogen peroxide leaching (such as CN120757131A) or methods using inorganic or organic acid leaching (such as CN118621359A). However, these mainstream methods generally have significant limitations: on the one hand, they often require the use of large amounts of strong acids (such as H2SO4 and HNO3), strong alkalis, or reducing agents (such as H2O2 and Na2S2O5), which not only pose high operational risks and are highly corrosive, but also lead to complex subsequent wastewater treatment and are prone to secondary pollution. On the other hand, these methods have relatively low selectivity for leaching lithium, with most reagents indiscriminately leaching all metal elements (such as lithium, iron, cobalt, nickel, and manganese) from the black powder, increasing the cost of impurity removal in the subsequent lithium extraction process. Furthermore, existing processes suffer from complexity, energy consumption, reagent consumption, and waste disposal issues, hindering their cost-effective large-scale scaling and severely limiting their large-scale industrial application. In contrast, electrochemical lithium removal (or lithium leaching) methods can be carried out at room temperature and pressure in mild neutral electrolytes, resulting in lower wastewater treatment costs and greater environmental friendliness. Additionally, electrochemical lithium removal exhibits high selectivity for lithium leaching, avoiding the need for subsequent individual removal of other elements from lithium-rich solutions, thus greatly simplifying the process. Moreover, electrochemical lithium removal can utilize green electricity to further reduce overall carbon emissions, making it cost-effective. However, existing electrochemical lithium removal technologies still face significant equipment bottlenecks in practical industrial applications, particularly for large-scale continuous processing of retired battery black powder. (1) Intermittent nature of traditional anode devices: In traditional electrochemical delithiation devices, the anode is usually composed of an electrode sheet with a fixed load of degraded black powder material. When the batch of black powder is delithiated, the entire electrolysis process must be interrupted in order to dismantle the depleted black powder anode and load a new black powder anode. This process is not only time-consuming and labor-intensive, but also limited by the physical size of the electrolytic cell, the amount of degraded black powder processed in a single operation is very limited. This intermittent operation mode results in low equipment utilization, low processing efficiency, and high labor costs, which seriously restricts its industrial scale-up and continuous production capacity.

[0005] (2) Discontinuity interruption caused by cathode capacity saturation (taking CN119843061A as an example): Patent application CN119843061A discloses a method for electrochemical lithium extraction from decommissioned lithium batteries assisted by a pseudocapacitive cathode. This technology utilizes a pseudocapacitive cathode to adsorb non-lithium cations (such as Na+) in the electrolyte. + K +Replacing the hydrogen evolution reaction with a pseudocapacitive cathode (such as the anode) can reduce the total delithiation voltage to some extent. However, this approach has a key limitation: when the cations adsorbed by the pseudocapacitive cathode reach its material capacity limit, the cathode loses its function and must be stopped and replaced. Similar to replacing the anode, this also requires interrupting the entire delithiation process. Therefore, although this technology can reduce energy consumption in the electrochemical delithiation process to some extent, its cathode still needs frequent replacement, making the entire process essentially intermittent and difficult to meet the industrial requirements for large-scale, continuous, and uninterrupted delithiation of retired black powder.

[0006] In summary, although electrochemical delithiation has advantages in principle such as environmental friendliness, high selectivity, and low carbon emissions, existing technologies (including fixed anode designs and solutions such as CN119843061A) cannot achieve truly continuous and large-scale operation due to frequent interruptions caused by device design (whether replacing the anode or cathode). Therefore, there is an urgent need to develop a new type of electrochemical delithiation device that can overcome the above-mentioned interruption problems and support continuous, large-scale processing of retired battery black powder. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the existing technology by providing an electrochemical delithiation device and method for recovering lithium from retired lithium-ion battery black powder. The device of this invention is an electrochemical apparatus for large-scale processing of retired lithium-ion battery black powder. It is a scalable electrochemical delithiation device with a simple design. Through the cooperation of an electric unwinding machine, an electric winding machine, and a movable anode plate containing the black powder material, and by replacing the traditional hydrogen evolution reaction with an oxygen reduction reaction on the cathode side, large-scale, efficient, and continuous processing of retired black powder is achieved.

[0008] This invention can be achieved through the following technical solutions: The first objective of this invention is to provide an electrochemical delithiation device for recovering lithium from retired lithium-ion battery black powder, the electrochemical delithiation device comprising an electrolytic cell, a movable anode electrode, a cathode electrode, an electric unwinding machine, an electric winding machine, and a cleaning mechanism; The movable anode electrode includes a current collector and an active material connected to the current collector, specifically: the active material is coated on the current collector; The active material of the movable anode electrode includes black powder material; The movable anode sheet is connected to an electric unwinding machine and an electric winding machine on both sides, respectively. The electric unwinding machine and the electric winding machine are used to drive the movable anode sheet to move continuously. The cleaning mechanism is located downstream of the electrolytic cell and is used to remove residual lithium ions from the surface of the movable anode electrode. The cathode electrode is arranged on at least one side of the movable anode electrode; The electrolytic cell is used to contain the electrolyte; The movable anode is partially immersed in the electrolyte, and the cathode is fully or partially immersed in the electrolyte, so as to selectively extract lithium from the black powder material on the movable anode into the electrolyte.

[0009] Furthermore, the method for preparing the movable anode electrode includes the following steps: The black powder material, conductive agent, binder and solvent are mixed to form an electrode paste; The obtained electrode slurry is coated onto the current collector, leaving a blank current collector. Single-sided or double-sided coating is performed. After coating, the electrode sheet is dried and then wound up to obtain the movable anode electrode sheet.

[0010] Furthermore, the two sides of the movable anode sheet are respectively wound on an electric unwinding machine and an electric winding machine.

[0011] Furthermore, the black powder material, conductive agent, binder, and solvent are uniformly mixed by stirring and ultrasonic dispersion.

[0012] Furthermore, the black powder material is a decommissioned black powder material.

[0013] Furthermore, the black powder material is a retired lithium-ion battery material.

[0014] Furthermore, the black powder material includes one or more of lithium iron phosphate, graphite, ternary materials, lithium cobalt oxide, and lithium manganese oxide (e.g., lithium iron phosphate / graphite mixture, ternary material / graphite mixture, lithium cobalt oxide / graphite mixture).

[0015] Furthermore, the conductive agent is at least one of carbon materials such as acetylene black, conductive carbon black (such as Super P), carbon nanotubes, and graphene.

[0016] Furthermore, the adhesive is at least one of the following materials: polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC), and polytetrafluoroethylene (PTFE).

[0017] Furthermore, the solvent is at least one of N-methylpyrrolidone (NMP), water, etc.

[0018] Furthermore, the current collector is at least one of carbon-based materials (including but not limited to carbon cloth, carbon paper, carbon fiber, carbon felt, graphite paper, etc.), titanium mesh, titanium foil, nickel foam, and aluminum foil.

[0019] Furthermore, the drying temperature is 60-120°C. C.

[0020] Furthermore, the area loading of the black powder material coated on the current collector is 1~50 mg·cm³. -2 .

[0021] More preferably, the area loading of the black powder material coated on the current collector is 5~20 mg·cm³. -2 .

[0022] Furthermore, the weight ratio of black powder material, conductive agent, and binder is (5~20):(1~2):(0.2~2).

[0023] More preferably, the weight ratio of the black powder material, the conductive agent, and the binder is 8:1:1.

[0024] Furthermore, the weight ratio of adhesive to solvent is 1:(10~40).

[0025] More preferably, the weight ratio of adhesive to solvent is 1:20.

[0026] Furthermore, the electric unwinder is located upstream of the electrolytic cell; the electric winding machine is located downstream of the cleaning mechanism.

[0027] Furthermore, the movable anode sheet is unwound by the electric unwinding machine and then sequentially conveyed to the electrolytic cell and the cleaning mechanism before being wound up in the electric rewinding machine.

[0028] Optionally, the direction of movement of the movable anode plate, which is continuously moved by an electric unwinder, is determined by the shape of the electrolytic cell.

[0029] More preferably, the electric unwinder and electric rewinder are used to drive the movable anode sheet to move continuously horizontally or vertically.

[0030] Optionally, the electrochemical delithiation device further includes a guiding assembly; the guiding assembly includes a first guiding assembly and a second guiding assembly, the first guiding assembly includes a plurality of first guide members, the second guiding assembly includes a plurality of second guide members, the first guiding assembly is positioned higher than the second guiding assembly, all adjacent first guide members are at the same height, and all adjacent second guide members are at the same height; the horizontal movement of the movable anode plate is achieved by continuously bypassing the first guide members or continuously bypassing the second guiding assembly, and the vertical or inclined movement of the movable anode plate is achieved by alternately bypassing the first guide members and the second guide members.

[0031] Furthermore, the cathode electrode is one or more of a Pt-based material electrode and a metal-doped carbon-based electrode.

[0032] Furthermore, the cathode electrode is fixed to at least one side of the movable anode electrode, and the specific position depends on the shape of the electrolytic cell.

[0033] Furthermore, the platinum-based material electrode is selected from one or more of Pt sheets, Pt meshes, Pt wires, porous electrodes loaded with nano-Pt or Pt-based composite materials.

[0034] Furthermore, the electrolytic cell is selected from one or more of the following: cuboid electrolytic cell, H-type electrolytic cell, and cylindrical electrolytic cell.

[0035] Specifically, in the cuboid electrolytic cell, the movement of the movable anode electrode includes horizontal movement and vertical movement. When moving horizontally, the cathode electrode is located above or below the movable anode electrode; when moving vertically, the cathode electrode is located to the left or right of the movable anode electrode; the number of cathode electrodes is ≥1.

[0036] Specifically, the H-type electrolytic cell consists of an anode chamber and a cathode chamber connected by an electrolyte. The electrochemical delithiation process takes place in the anode chamber, and the movable anode electrode can be moved by an electric unwinding machine. In the cathode chamber, oxygen-containing gas is introduced into the electrolyte around the cathode electrode to cause an oxygen reduction reaction.

[0037] Furthermore, the electrolyte is at least one selected from Na2SO4 aqueous solution, Na2CO3 aqueous solution, NaCl aqueous solution, KCl aqueous solution, K2SO4 aqueous solution, NaNO3 aqueous solution, and KNO3 aqueous solution.

[0038] Furthermore, the electrolytic cell may be agitated or equipped with an agitator, which is used to promote mass transfer of the electrolyte, lithium removal reaction on the anode side, and oxygen reduction reaction on the cathode side.

[0039] Furthermore, the cleaning mechanism is located downstream of the electrolytic cell, and the cleaning mechanism contains water (preferably deionized water), and the number of cleaning mechanisms is ≥1.

[0040] Furthermore, a portion of the surface of the movable anode plate in the electrolyte of the electrolytic cell is parallel to the surface of the cathode plate 12.

[0041] The second objective of this invention is to provide a method for using an electrochemical delithiation device for recovering lithium from retired lithium-ion battery black powder. The method utilizes the aforementioned electrochemical delithiation device to achieve delithiation, and includes the following steps: Start the electric unwinding machine to move the unlithiated area of ​​the movable anode electrode into the electrolyte, connect the external power supply to power the electrochemical delithiation device, and perform electrochemical delithiation of the movable anode electrode immersed in the electrolyte.

[0042] Furthermore, after the movable anode plate immersed in the electrolyte has completed delithiation, the external power supply is disconnected; the electric unwinding machine is started to move the undelithiation area of ​​the movable anode plate into the electrolyte for electrochemical delithiation, and the delithiation area of ​​the movable anode plate is moved downstream to the cleaning mechanism.

[0043] Further, repeat the above steps until all the wound movable anode plates have been delithiated, and then collected by the electric rewinder downstream of the cleaning mechanism.

[0044] Furthermore, the method includes the following steps: (1) Start the electric unwinding machine and the electric winding machine to supply the movable anode sheet to the electrolytic cell, and then stop the electric unwinding machine and the electric winding machine to perform electrochemical delithiation of the movable anode sheet immersed in the electrolyte. (2) When the electrochemical delithiation of the movable anode plate immersed in the electrolyte in step (1) is completed, start the electric unwinding machine and the electric winding machine to move the un-delithiation area of ​​the movable anode plate into the electrolytic cell for electrochemical delithiation. At the same time, move the delithiation area of ​​the movable electrode plate to the cleaning mechanism to remove the residual lithium ions on the surface of the movable anode plate in the cleaning mechanism to achieve further delithiation. During the further delithiation process, the electric unwinding machine and the electric winding machine are stopped. (3) Repeat step (2) until all the black powder material of the wound movable anode sheet has been delithiated, and then the downstream winding machine of the cleaning mechanism collects all the delithiated movable anode sheets.

[0045] Furthermore, after step (3), the following step (4) is also included: (4) Collect the lithium-ion-rich electrolyte from the electrolytic cell and the lithium-containing solution from the cleaning mechanism to obtain a lithium-containing solution, concentrate it, and extract lithium.

[0046] Further, in the method, the method of concentrating and extracting lithium is to evaporate and concentrate the lithium-containing solution until the lithium element concentration is about 20-40 g / L, then add saturated sodium carbonate solution and react at 50-80℃ (preferably 60℃) and stirring speed of 200-500 rpm (preferably 300 rpm) for 1-5 h (preferably 2 h), and filter to obtain Li2CO3 precipitate.

[0047] Furthermore, in the method, the criterion for determining that the movable anode is completely delithiated is that the lithium content in the movable anode is reduced by more than 95% compared to the content in the initial movable anode.

[0048] Furthermore, during the electrochemical delithiation process, oxygen-containing gas is continuously supplied to the electrolyte region near the cathode electrode, causing an oxygen reduction reaction to occur on the cathode electrode.

[0049] Furthermore, the oxygen-containing gas may be one or more of air, pure oxygen, and oxygen-enriched gas.

[0050] Furthermore, an electrical signal is applied between the movable anode and cathode to achieve the electrochemical delithiation process. The electrical signal is applied in one of the following ways: constant voltage, constant current, or alternating constant current and constant voltage.

[0051] Furthermore, a constant voltage method is used: the voltage range is 0.1 V to 4.0 V, and the single delithiation time is 5 to 300 min.

[0052] Furthermore, a constant current method is employed: the current range is 0.1 mA·cm. -2 ~ 10mA·cm -2 The time for a single delithiation is 5 to 300 minutes.

[0053] Furthermore, an alternating method of constant current and constant voltage is employed: the voltage range during the constant voltage process is 0.1 V to 4.0 V, and the current range during the constant current process is 0.1 mA·cm. -2 ~ 10mA·cm -2 The time for a single constant voltage delithiation is 5~300 min, and the time for a single constant current delithiation is 5~300 min.

[0054] This invention provides an electrochemical delithiation device for recovering lithium from retired lithium-ion battery black powder, enabling large-scale, low-energy, and continuous processing of retired black powder. One core component of this device is an integrated electrochemical reaction delithiation system: a movable anode electrode made of retired black powder material, driven by an electric unwinding machine, can move continuously (preferably continuously horizontally or vertically); a cathode electrode is fixedly arranged on at least one side of the movable anode electrode. When the power is turned on, lithium from the retired black powder material in the movable anode electrode is extracted and enters the electrolyte. The movable anode electrode, after being delithiated by the electrochemical delithiation device, then enters a downstream cleaning mechanism to remove residual lithium ions from its surface. After the movable anode electrode has undergone delithiation, the lithium-rich electrolyte from the electrochemical delithiation device and the lithium-containing solution from the cleaning device can be collected, concentrated, and lithium extracted. A second core component of this device is the replacement of the conventional cathode hydrogen evolution reaction with an oxygen reduction reaction having a more positive electrode potential, achieving low-energy electrochemical delithiation.

[0055] Compared with the prior art, the present invention has the following beneficial effects: 1) The present invention provides an electrochemical delithiation device and method for recovering lithium from retired lithium-ion battery black powder. The device of the present invention is an electrochemical device for large-scale processing of retired lithium-ion battery black powder. It is a scalable electrochemical delithiation device with a simple design. It is matched with a continuously movable anode plate made of retired battery black powder material driven by an electric unwinding machine, and an oxygen reduction reaction matched on the cathode side. It can reduce the voltage applied for electrochemical delithiation and reduce energy consumption. It can realize large-scale and continuous electrochemical delithiation of retired black powder, and can realize large-scale, efficient, low-energy consumption and continuous processing of retired black powder.

[0056] 2) The electrochemical delithiation device and method for recovering lithium from retired lithium-ion battery black powder provided by this invention employs a method of continuously introducing oxygen-containing gas into the electrolyte region around the cathode side, replacing the traditional cathode hydrogen evolution reaction with an oxygen reduction reaction, which can reduce the delithiation voltage and energy consumption. Since oxygen can be continuously introduced into the cathode side during the continuous delithiation process, a continuous oxygen reduction reaction is generated to receive electrons lost from the delithiation of black powder from the anode side, thus eliminating the need to replace the cathode plate.

[0057] 3) The present invention provides an electrochemical delithiation device and method for recovering lithium from retired lithium-ion battery black powder, which replaces the cathode hydrogen evolution reaction in the conventional system with an oxygen reduction reaction having a positive electrode potential, thereby achieving low-energy electrochemical delithiation. Attached Figure Description

[0058] In this invention, all figures are schematic and not drawn to scale.

[0059] Figure 1 This is a schematic diagram of the structure of an electrochemical delithiation device for recovering lithium from retired lithium-ion battery black powder, as described in an embodiment of the present invention. Figure 1 ; Figure 2 This is a schematic diagram of the structure of an electrochemical delithiation device for recovering lithium from retired lithium-ion battery black powder, as described in an embodiment of the present invention. Figure 2 ; Figure 3 This is a schematic diagram of the structure of an electrochemical delithiation device for recovering lithium from retired lithium-ion battery black powder, as described in an embodiment of the present invention. Figure 3 ; Figure 4 This is a schematic diagram of the structure of an electrochemical delithiation device for recovering lithium from retired lithium-ion battery black powder, as described in an embodiment of the present invention. Figure 4 ; Figure 5 This is a schematic diagram of the structure of an electrochemical delithiation device for recovering lithium from retired lithium-ion battery black powder, as described in an embodiment of the present invention. Figure 5 ; Figure 6 This is a schematic diagram of the structure of the movable anode plate (black powder anode plate) in an embodiment of the present invention; Figure 7 These are the ICP results of lithium in the leaching decommissioned ternary NCM955, NCM523 and NCM111 powders in the embodiments and comparative examples of the present invention, wherein (a) the electrochemical method of the embodiments is used, and (b) the conventional chemical method of the comparative examples is used, and the Y-axis represents the leaching rate of each metal element.

[0060] Figure label: 100-Electrolytic cell; 11-Movable anode plate; 12-Cathode plate; 200 - Cleaning facility; 21-Electric unwinding machine; 22-Electric winding machine; 31-Current collector; 32-Active substance. Detailed Implementation

[0061] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0062] In the description of the invention, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0063] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of the present invention can be combined with each other to form new technical solutions.

[0064] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection achieved by screw fastening, welding, or cooperation with a seal; they can also refer to a direct or indirect connection between components, or an interaction relationship achieved through other elements; they can be a fixed connection, a detachable connection, or an integral part; they can be a mechanical connection or an electrical connection; they can be a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction relationship between two components; "upper," "lower," "left," "right," etc., are only used to indicate relative positional relationships, and the relative positional relationship may change when the absolute position of the described object changes. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0065] It should be noted that in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations, nor should they be construed as limiting their quantity, order, priority, or importance. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0066] In this invention, any component models, material names, connection structures, control methods, etc., not explicitly stated are considered common technical features disclosed in the prior art.

[0067] Example 1 This embodiment provides an electrochemical delithiation device for recovering lithium from retired lithium-ion battery black powder. The electrochemical delithiation device includes an electrolytic cell 100, a movable anode plate 11, a cathode plate 12, an electric unwinding machine 21, an electric winding machine 22, and a cleaning mechanism 200.

[0068] The movable anode plate 11 includes a current collector 31 and an active material 32 connected to the current collector 31; the active material 32 of the movable anode plate 11 includes black powder material; both sides of the movable anode plate 11 are respectively connected to an electric unwinding machine 21 and an electric winding machine 22, which are used to drive the movable anode plate 11 to move continuously; the cleaning mechanism 200 is located downstream of the electrolytic cell 100, and the cleaning mechanism 200 is used to remove residual lithium ions on the surface of the movable anode plate 11; the cathode plate 12 is arranged on at least one side of the movable anode plate 11; the electrolytic cell 100 is used to contain electrolyte; the movable anode plate 11 is partially immersed in the electrolyte, and the cathode plate 12 is fully or partially immersed in the electrolyte, so as to selectively extract lithium from the black powder material on the movable anode plate 11 into the electrolyte.

[0069] The movable anode plate 11 of the electrochemical delithiation device in this embodiment is made from black powder material and is driven to move continuously horizontally or vertically by an electric unwinding machine 21 and an electric winding machine 22. The cathode plate 12 of the device is fixedly arranged on at least one side of the movable anode plate 11. During delithiation, an electrolyte is injected into the electrolytic cell 100 of the electrochemical delithiation device, and oxygen-containing gas is continuously introduced into the electrolyte area around the cathode plate 12. The movable anode plate 11, which has been delithiated by the electrochemical delithiation device, then enters the downstream cleaning mechanism 200 to remove the lithium ions remaining on its surface. The lithium-rich electrolyte in the electrolytic cell and the lithium-containing solution in the cleaning mechanism 200 are collected, concentrated, and lithium is extracted.

[0070] In this embodiment, the cleaning mechanism 200 includes a cleaning tank. The cleaning mechanism 200 is suitable for cleaning the anode sheet after electrochemical delithiation to remove residual lithium ions from the surface. It should be noted that those skilled in the art can select the specific number and type of the cleaning mechanism 200 according to actual needs, as long as the above functions can be achieved, which will not be elaborated here.

[0071] refer to Figure 6 The movable anode electrode 11 includes a current collector 31 and an active material 32. The active material 32 is coated on one or both surfaces of the current collector 31, with a portion of the current collector 31 left uncoated. It should be noted that those skilled in the art can select the specific types of the current collector 31 and the active material 32 according to actual needs. For example, the current collector 31 can be at least one of carbon-based materials (including but not limited to carbon cloth, carbon paper, carbon fiber, carbon felt, graphite paper, etc.), titanium mesh, titanium foil, nickel foam, and aluminum foil. The black powder material in the active material 32 can be at least one of lithium iron phosphate, lithium iron phosphate / graphite mixture, graphite, ternary materials, ternary materials / graphite mixture, lithium cobalt oxide, lithium cobalt oxide / graphite, lithium manganese oxide, lithium manganese oxide / graphite mixture, and lithium manganese oxide. Furthermore, the size of the current collector 31 can be selected according to actual needs, as long as the above functions can be achieved; further details are omitted here.

[0072] The method for preparing the movable anode plate 11 includes the following steps: The black powder material, conductive agent, binder, and solvent are uniformly mixed by stirring and ultrasonic dispersion to form a uniform electrode slurry; The obtained electrode slurry is coated onto the current collector, leaving a portion of the current collector blank. Single-sided or double-sided coating is performed. After coating, the electrode sheet is dried and then wound up to obtain the movable anode electrode sheet 11.

[0073] The movable anode plate 11 is wound on both sides of an electric unwinding machine 21 and an electric winding machine 22, respectively.

[0074] The black powder material is a retired lithium-ion battery material.

[0075] The conductive agent is at least one of carbon materials such as acetylene black, conductive carbon black (such as Super P), carbon nanotubes, and graphene.

[0076] The adhesive is at least one of the following materials: polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC), and polytetrafluoroethylene (PTFE).

[0077] The solvent is at least one of N-methylpyrrolidone (NMP), water, etc.

[0078] The drying temperature is 60-120°C. C.

[0079] The area loading of black powder material coated on the current collector is 1~50 mg·cm. -2 .

[0080] The weight ratio of black powder material, conductive agent, and binder is (5~20):(1~2):(0.2~2). Preferably, the weight ratio of black powder material, conductive agent, and binder is 8:1:1.

[0081] The weight ratio of adhesive to solvent is 1:(10~40). Preferably, the weight ratio of adhesive to solvent is 1:20.

[0082] The cathode electrode 12 is one or more of a Pt-based material electrode and a metal-doped carbon-based electrode.

[0083] The platinum-based material electrode is selected from one or more of Pt sheets, Pt meshes, Pt wires, porous electrodes loaded with nano-Pt or Pt-based composite materials.

[0084] The electrolyte is at least one of the following: Na2SO4 aqueous solution, Na2CO3 aqueous solution, NaCl aqueous solution, KCl aqueous solution, K2SO4 aqueous solution, NaNO3 aqueous solution, and KNO3 aqueous solution.

[0085] The electric unwinder 21 is located upstream of the electrolytic cell 100; the electric winding machine 22 is located downstream of the cleaning mechanism 200.

[0086] The movable anode plate 11 is unwound by the electric unwinder 21 and then sequentially conveyed to the electrolytic cell 100 and the cleaning mechanism 200 before being wound up in the electric rewinder 22.

[0087] The electric unwinder 21 and electric rewinder 22 are used to drive the movable anode plate 11 to move continuously horizontally or vertically. When moving horizontally, the cathode plate 12 is located above or below the movable anode plate 11; when moving vertically, the cathode plate 12 is located to the left or right of the movable anode plate 11.

[0088] The electrochemical delithiation device further includes a guiding assembly, through which the movable anode electrode 11 can move stably in different directions. The guiding assembly includes a first guiding assembly and a second guiding assembly. The first guiding assembly includes multiple first guide members, and the second guiding assembly includes multiple second guide members. The first guiding assembly is positioned higher than the second guiding assembly. All adjacent first guide members are at the same height, and all adjacent second guide members are at the same height. The movable anode electrode 11 can be moved horizontally by continuously bypassing the first guide members or continuously bypassing the second guiding assembly, and can be moved vertically by alternately bypassing the first and second guide members.

[0089] The direction of movement of the movable anode plate 11, which is continuously moved by the electric unwinding machine 21, is determined by the shape of the electrolytic cell 100.

[0090] The cathode electrode 12 is fixed to at least one side of the movable anode electrode 11, and the specific position depends on the shape of the electrolytic cell 100.

[0091] The electrolytic cell 100 is selected from one or more of the following: cuboid electrolytic cell, H-type electrolytic cell, and cylindrical electrolytic cell.

[0092] Specifically, in the cuboid electrolytic cell, the movement of the movable anode plate 11 includes horizontal movement and vertical movement. When moving horizontally, the cathode plate 12 is located above or below the movable anode plate 11; when moving vertically, the cathode plate 12 is located to the left or right of the movable anode plate 11; the number of cathode plates 12 is ≥1.

[0093] Specifically, the H-type electrolytic cell consists of an anode chamber and a cathode chamber connected by an electrolyte. The electrochemical delithiation process takes place in the anode chamber. The movable anode electrode 11 can be moved by an electric unwinding machine 21, and the movable anode electrode 11 moves vertically in the anode chamber. The cathode electrode 12 is in the cathode chamber. In the cathode chamber, oxygen-containing gas is continuously introduced into the electrolyte around the cathode electrode 12 to generate a continuous oxygen reduction reaction, so as to continuously receive electrons from the delithiation side.

[0094] The cleaning mechanism 200 is located downstream of the electrolytic cell 100, and the cleaning mechanism 200 contains water (preferably deionized water). The number of cleaning mechanisms 200 is ≥1.

[0095] The electrolytic cell 100 may be agitated or may be equipped with an agitator. The agitator is used to promote the mass transfer of the electrolyte, the delithiation reaction on the anode side, and the oxygen reduction reaction on the cathode side. Conventional agitators can be used, and this invention does not improve upon them.

[0096] The surface of the movable anode 11 in the electrolyte of the electrolytic cell 200 is relatively parallel to the surface of the cathode 12.

[0097] For this embodiment, as Figure 1 The image shows one implementation of an electrochemical delithiation device for recovering lithium from retired lithium-ion battery black powder. The electrolytic cell 100 is a cuboid electrolytic cell, and the cathode electrode 12 is fixed to one side (below) of the movable anode electrode 11. Both the movable anode electrode 11 and the cathode electrode 12 are horizontally arranged, and a cleaning mechanism 200 is provided.

[0098] For this embodiment, as Figure 2 As shown, this is another implementation of an electrochemical delithiation device for recovering lithium from retired lithium-ion battery black powder. The electrolytic cell 100 is a cuboid electrolytic cell, and the cathode electrode 12 is fixed on both sides (above and below) of the movable anode electrode 11. Both the movable anode electrode 11 and the cathode electrode 12 are horizontally arranged, and a cleaning mechanism 200 is provided.

[0099] For this embodiment, as Figure 3 As shown, this is another implementation of an electrochemical delithiation device for recovering lithium from retired lithium-ion battery black powder. The electrolytic cell 100 is a cuboid electrolytic cell, and the cathode electrode 12 is fixed on both sides of the movable anode electrode 11. Both the movable anode electrode 11 and the cathode electrode 12 are arranged vertically, and a cleaning mechanism 200 is provided.

[0100] For this embodiment, as Figure 4 As shown, this is another implementation of an electrochemical delithiation device for recovering lithium from retired lithium-ion battery black powder. The electrolytic cell 100 is a cuboid electrolytic cell. The cathode electrode 12 is fixed on both sides of the movable anode electrode 11. The movable anode electrode 11 and the cathode electrode 12 are both vertically arranged. Multiple movable anode electrodes 11 are arranged at intervals. A cathode electrode 12 is arranged between adjacent movable anode electrodes 11. A cleaning mechanism 200 is provided.

[0101] For this embodiment, as Figure 5As shown, this is another implementation of an electrochemical delithiation device for recovering lithium from retired lithium-ion battery black powder. The electrolytic cell 100 is an H-type electrolytic cell, which consists of an anode chamber and a cathode chamber connected by an electrolyte. The cathode electrode 12 is fixed on one side of the movable anode electrode 11. Specifically, the cathode electrode 12 is placed in the cathode chamber, and the movable anode electrode 11 is placed in the anode chamber. Both the movable anode electrode 11 and the cathode electrode 12 are arranged vertically. A cleaning mechanism 200 is provided.

[0102] During the electrochemical delithiation process, an oxygen-containing gas (which may be air, pure oxygen, and / or oxygen-enriched gas) is continuously supplied to the electrolyte region near the cathode electrode 12, causing an oxygen reduction reaction to occur on the cathode electrode 12.

[0103] This embodiment also provides a method for using an electrochemical delithiation device for recovering lithium from retired lithium-ion battery black powder. The method employs the aforementioned electrochemical delithiation device and includes the following steps: (1) Start the electric unwinding machine 21 and the electric winding machine 22 to supply the movable anode plate 11 to the electrolytic cell 100, and then stop the electric unwinding machine 21 and the electric winding machine 22 to perform electrochemical delithiation of the movable anode plate 11 immersed in the electrolyte. (2) When the electrochemical delithiation of the movable anode plate 11 immersed in the electrolyte in step (1) is completed, start the electric unwinding machine 21 and the electric winding machine 22 to move the un-delithiation area of ​​the movable anode plate 11 into the electrolytic cell 100 for electrochemical delithiation. At the same time, move the delithiation area of ​​the movable electrode plate to the cleaning mechanism 200 to remove the residual lithium ions on the surface of the movable anode plate 11 in the cleaning mechanism 200 to achieve further delithiation. During the further delithiation process, the electric unwinding machine 21 and the electric winding machine 22 are stopped. (3) Repeat step (2) until all the black powder material of the wound movable anode plate 11 has been delithiated, and the downstream winding machine of the cleaning mechanism 200 collects all the delithiated movable anode plates 11.

[0104] After step (3), the following step (4) may also be included: (4) Collect the lithium-ion-rich electrolyte in the electrolytic cell 100 and the lithium-containing solution in the cleaning mechanism 200 to obtain a lithium-containing solution, concentrate it, and extract lithium.

[0105] In the method, the method of concentrating and extracting lithium is to evaporate and concentrate the lithium-containing solution until the lithium element concentration is about 20-40 g / L, then add saturated sodium carbonate solution and react at 50-80℃ (preferably 60℃) and stirring speed of 200-500 rpm (preferably 300 rpm) for 1-5 h (preferably 2 h), and filter to obtain Li2CO3 precipitate.

[0106] In the method, the criterion for determining that the movable anode electrode 11 is completely delithiated is that the lithium content in the movable anode electrode is reduced by more than 95% compared with the content in the initial movable anode electrode.

[0107] During the electrochemical delithiation process, oxygen-containing gas is continuously supplied to the electrolyte region near the cathode electrode 12, causing an oxygen reduction reaction to occur on the cathode electrode 12.

[0108] The oxygen-containing gas may be one or more of air, pure oxygen, or oxygen-enriched gas.

[0109] In this embodiment, the electric unwinding machine 21 is started to move the undelithiated area of ​​the movable anode plate 11 into the electrolyte, and the external power supply is connected to power the electrochemical delithiation device, so that the movable anode plate 11 immersed in the electrolyte can be electrochemically delithiated; specifically, the external power supply can be divided into a constant current power supply and a constant voltage power supply.

[0110] An electrical signal is applied between the movable anode electrode 11 and the cathode electrode 12 to achieve the electrochemical delithiation process. The electrical signal is applied in one of the following ways: constant voltage, constant current, or alternating constant current and constant voltage.

[0111] A constant voltage method is used: the voltage range is 0.1 V-4.0 V, and the single delithiation time is 5-300 min.

[0112] A constant current method is used: the current range is 0.1 mA·cm. -2 ~ 10mA·cm -2 The time for a single delithiation is 5 to 300 minutes.

[0113] A method of alternating constant current and constant voltage is adopted: the voltage range during the constant voltage process is 0.1 V-4.0 V, and the current range during the constant current process is 0.1 mA·cm. -2 ~ 10mA·cm -2 The time for a single constant voltage delithiation is 5~300 min, and the time for a single constant current delithiation is 5~300 min.

[0114] After the movable anode plate 11 immersed in the electrolyte has completed delithiation, the external power supply is disconnected; the electric unwinding machine 21 is started, so that the undelithiation area of ​​the movable anode plate 11 is moved into the electrolyte for electrochemical delithiation, and the delithiation area of ​​the movable anode plate 11 is moved downstream to the cleaning mechanism 200.

[0115] Repeat the above steps until all the wound movable anode plates 11 have been delithiated, and then collected by the electric rewinder 22 downstream of the cleaning mechanism 200.

[0116] Example 2 This embodiment provides an electrochemical delithiation method for recovering lithium from retired lithium-ion battery black powder. This method is implemented using the electrochemical delithiation device for recovering lithium from retired lithium-ion battery black powder described in Example 1. This method is based on the method described in Example 1.

[0117] The method in this embodiment adopts Figure 1 The apparatus shown is used for the delithiation treatment of black powder materials from retired batteries.

[0118] The method includes the following steps: The movable anode electrode 11 undergoes electrochemical delithiation and cleaning processes sequentially to obtain a lithium-ion-rich electrolyte and a lithium-containing solution. The lithium-ion-rich electrolyte and lithium-containing solution are collected and concentrated for lithium extraction. The electrolytic cell 200 of the electrochemical delithiation device is a cuboid electrolytic cell (length > width > height). The movable anode electrode 11 moves within the electrolytic cell 200. The surface of the portion of the movable anode electrode 11 in the electrolyte within the electrolytic cell 200 is relatively parallel to the surface of the cathode electrode 12. In this embodiment, the opposing surfaces of the movable anode electrode 11 and the cathode electrode 12 are both horizontal planes.

[0119] In this embodiment, the movable anode electrode 11 is prepared by coating a black powder slurry formed by uniformly mixing retired LFP (retired lithium iron phosphate), conductive carbon black Super P, PVDF, and NMP onto graphite paper through stirring and ultrasonication. The mass ratio of retired LFP, conductive carbon black Super P, and PVDF is 8:1:1, the mass ratio of PVDF to NMP is 1:20, and the unit area loading of the black powder material coated on the graphite paper is 5 mg·cm³. -2 The electrolyte is a 0.1M Na₂SO₄ solution; the cathode 12 is a Pt metal sheet; pure oxygen is introduced into the electrolyte region where the cathode 12 is located; electrochemical delithiation uses a constant current followed by a constant voltage method, with a constant current density of 3 mA·cm⁻¹. -2 The constant current time was 5 min, and the voltage between the two electrodes (cathode 12 and movable anode 11) was monitored simultaneously during the constant current process, with the voltage value around 1.34V. The constant voltage was 1.2V, and the delithiation time was 25 min. The metal element content in the electrolyte after the above delithiation was tested using ICP-OES. The results showed that the lithium ion leaching rate was over 99%, while the iron leaching rate was less than 0.1%, proving the high selectivity of the above electrochemical method for lithium leaching. Furthermore, the obtained lithium-ion-rich electrolyte and lithium-containing solution were mixed, and the lithium concentration was concentrated by evaporation until it reached 20 g / L. Then, saturated sodium carbonate solution was added, and the reaction was carried out at 60℃ and a stirring speed of 300 rpm for 2 h. The precipitate of Li2CO3 was obtained by filtration, thus completing the extraction of lithium.

[0120] Example 3 This embodiment provides an electrochemical delithiation method for recovering lithium from retired lithium-ion battery black powder. This method is implemented using the electrochemical delithiation device for recovering lithium from retired lithium-ion battery black powder described in Example 1. This method is based on the method described in Example 1.

[0121] The method in this embodiment adopts Figure 3 The apparatus shown is used for the delithiation treatment of black powder materials from retired batteries.

[0122] The method includes the following steps: The movable anode electrode 11 undergoes electrochemical delithiation and cleaning processes sequentially to obtain a lithium-ion-rich electrolyte and a lithium-containing solution. The lithium-ion-rich electrolyte and lithium-containing solution are collected and concentrated for lithium extraction. The electrolytic cell 200 of the electrochemical delithiation device is a rectangular electrolytic cell (height > width > length), and the movable anode electrode 11 moves vertically within the electrolytic cell 200.

[0123] In this embodiment, the movable anode plate 11 is prepared by coating a black powder slurry formed by uniformly mixing retired NCM955 (or retired NCM523, retired NCM111, i.e., retired ternary materials), conductive carbon black Super P, PVDF, and NMP onto graphite paper through stirring and ultrasonication. The mass ratio of retired NCM955 (or retired NCM523, retired NCM111), conductive carbon black Super P, and PVDF is 8:1:1, the mass ratio of PVDF to NMP is 1:20, and the unit area loading of the black powder material coated on the graphite paper is 5 mg·cm³. -2 The electrolyte was a 0.1M Na₂SO₄ solution; the cathode 12 was a Pt metal sheet; pure oxygen was introduced into the electrolyte region containing the cathode 12; a constant voltage power supply of 2.25V was used for electrochemical delithiation, and the delithiation time was 30 min; the metal element content in the electrolyte after the delithiation was completed was tested using ICP-OES. The results are as follows: Figure 7 As shown in Figure a, the electrochemical delithiation in this embodiment achieves a lithium leaching rate of over 99.9%, while the leaching rates of Co, Ni, and Mn are all below 0.15%. Further, the obtained lithium-ion-rich electrolyte and lithium-containing solution are mixed, and the mixture is concentrated by evaporation until the lithium concentration reaches 20 g / L. Then, a saturated sodium carbonate solution is added, and the reaction is carried out at 60°C with a stirring speed of 300 rpm for 2 hours. The mixture is then filtered to obtain Li₂CO₃ precipitate, thus completing the extraction of lithium.

[0124] Comparative Example 1 This comparative example provides an electrochemical delithiation device for recovering lithium from retired lithium-ion battery black powder. In this comparative example, compared to the device in Example 1, the electric unwinding machine 21 and the electric winding machine 22 are not included. Anode plates of a certain size are cut and placed parallel to cathode plates within the electrolytic cell area. The size of the anode plate is less than or equal to the size of the cathode plate. The anode plate is connected to the electrode clamp, and the plate size is limited by the size of the electrolytic cell.

[0125] After the anode electrode immersed in the electrolyte has completed delithiation, it needs to be replaced with a new anode electrode that has not been delithlated, making it impossible to achieve large-scale, efficient, and continuous recovery of lithium elements from retired lithium-ion battery black powder.

[0126] Comparative Example 2 This comparative example provides an electrochemical delithiation method for recovering lithium from retired lithium-ion battery black powder. This method is implemented using the electrochemical delithiation device for recovering lithium from retired lithium-ion battery black powder described in Example 1. This method is based on the method described in Example 1.

[0127] This comparative method adopts Figure 1 The apparatus shown is used for the delithiation treatment of black powder materials from retired batteries.

[0128] The method includes the following steps: The movable anode electrode 11 undergoes electrochemical delithiation and cleaning processes sequentially to obtain a lithium-ion-rich electrolyte and a lithium-containing solution. The lithium-ion-rich electrolyte and lithium-containing solution are collected and concentrated for lithium extraction. The electrolytic cell 200 of the electrochemical delithiation device is a cuboid cell (length > width > height). The movable anode electrode 11 moves horizontally within the electrolytic cell 200. The surface of the portion of the movable anode electrode 11 in the electrolyte within the electrolytic cell 200 is relatively parallel to the surface of the cathode electrode 12. In this comparative example, the opposing surfaces of the movable anode electrode 11 and the cathode electrode 12 are both horizontal planes.

[0129] In this comparative example, the movable anode electrode 11 is prepared by coating a black powder slurry formed by uniformly mixing retired LFP (retired lithium iron phosphate), conductive carbon black Super P, PVDF, and NMP onto graphite paper through stirring and ultrasonication. The mass ratio of retired LFP, conductive carbon black Super P, and PVDF is 8:1:1, the mass ratio of PVDF to NMP is 1:20, and the unit area loading of the black powder material coated on the graphite paper is 5 mg·cm³. -2 The electrolyte is a 0.1M Na₂SO₄ solution; the cathode 12 is a Pt metal sheet; no oxygen-containing gas flows through the electrolyte region where the cathode 12 is located; electrochemical delithiation uses a constant current followed by a constant voltage method, with a constant current density of 3 mA·cm⁻¹. -2The constant current time was 5 min, the constant voltage was 1.2 V, and the constant voltage delithiation time was 25 min. During the constant current process, the voltage between the two electrodes (cathode 12 and movable anode 11) was monitored simultaneously, and the voltage value was approximately 2.2 V. Clearly, at the same delithiation current density, this voltage value is significantly higher than the voltage in Example 2 (i.e., 1.34 V), indicating that in Example 2, purging oxygen at the cathode significantly reduces the total voltage applied for delithiation. The metal element content in the electrolyte after the above delithiation was tested using ICP-OES. The results showed that without purging oxygen at the cathode 12, the lithium leaching rate under the same delithiation conditions only reached approximately 90%, significantly lower than the lithium leaching rate in Example 2. This further demonstrates that purging oxygen at the cathode can improve the electrochemical delithiation efficiency.

[0130] Comparative Example 3 This comparative example provides a traditional chemical reaction delithiation method for recovering lithium from retired lithium-ion battery black powder, including the following steps: 200 mg of decommissioned NCM955 powder was mixed with 20 mL of 98% concentrated formic acid (FA) to obtain a mixture. This mixture was heated to 50°C in an oil bath at a constant speed and held at that temperature. After reacting for 12 hours, the residual solids and liquid were separated by centrifugation to obtain a separate liquid. The metal element content in the separate liquid (i.e., the leachate) was tested using ICP-OES. 200 mg of decommissioned NCM523 powder was mixed with 20 mL of 98% concentrated formic acid (FA) to obtain a mixture. This mixture was heated to 50°C in an oil bath at a constant speed and held at that temperature. After reacting for 12 hours, the residual solids and liquid were separated by centrifugation to obtain a separate liquid. The metal element content in the separate liquid (i.e., the leachate) was tested using ICP-OES. 200 mg of decommissioned NCM111 powder was mixed with 20 mL of 98% concentrated formic acid (FA) to obtain a mixture. This mixture was heated to 50°C in an oil bath at a constant speed and held at that temperature. After reacting for 12 hours, the residual solid and liquid were separated by centrifugation to obtain a separated solution. The metal element content in the separated solution (i.e., the leachate) was tested using ICP-OES. Figure 7 As shown in b, the traditional chemical reaction delithiation method achieves a lithium leaching rate of over 93%, while the leaching rates of Co, Ni, and Mn reach only 1-5%. Clearly, this chemical method significantly outperforms the electrochemical delithiation method used in Example 3 (electrochemical delithiation results are shown in Figure b). Figure 7 (As shown in a). This indicates that electrochemical delithiation has a higher selectivity for lithium.

[0131] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles and methods described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. An electrochemical delithiation method for recovering lithium from retired lithium-ion battery black powder, characterized in that, The method is achieved using an electrochemical delithiation device for recovering lithium from retired lithium-ion battery black powder; The electrochemical delithiation device includes an electrolytic cell, a movable anode electrode, a cathode electrode, an electric unwinding machine, an electric winding machine, and a cleaning mechanism. The movable anode electrode includes a current collector and an active material connected to the current collector; The active material of the movable anode electrode includes black powder material; The movable anode sheet is connected to an electric unwinding machine and an electric winding machine on both sides, respectively. The electric unwinding machine and the electric winding machine are used to drive the movable anode sheet to move continuously. The cleaning mechanism is located downstream of the electrolytic cell and is used to remove residual lithium ions from the surface of the movable anode electrode. The cathode electrode is arranged on at least one side of the movable anode electrode; The electrolytic cell is used to contain the electrolyte; The movable anode is partially immersed in the electrolyte, and the cathode is fully or partially immersed in the electrolyte, so as to selectively extract lithium from the black powder material on the movable anode into the electrolyte. The method includes the following steps: (1) Start the electric unwinding machine and the electric winding machine to supply the movable anode sheet to the electrolytic cell, and then stop the electric unwinding machine and the electric winding machine to perform electrochemical delithiation of the movable anode sheet immersed in the electrolyte. (2) When the electrochemical delithiation of the movable anode sheet immersed in the electrolyte in step (1) is completed, start the electric unwinding machine and the electric winding machine to move the un-delithiation area of ​​the movable anode sheet into the electrolytic cell for electrochemical delithiation. At the same time, move the delithiation area of ​​the movable anode sheet to the cleaning mechanism to remove the residual lithium ions on the surface of the movable anode sheet in the cleaning mechanism to achieve further delithiation. During the further delithiation process, the electric unwinding machine and the electric winding machine are stopped. (3) Repeat step (2) until all the black powder material of the wound movable anode sheet has been delithiated, and then the electric rewinder downstream of the cleaning mechanism collects all the delithiated movable anode sheets. The electrolyte region near the cathode electrode is continuously supplied with oxygen-containing gas, causing an oxygen reduction reaction to occur on the cathode electrode. The oxygen-containing gas is selected from one or more of air, pure oxygen, and oxygen-enriched gas; In the electrochemical delithiation process, an electrical signal is applied between the movable anode and cathode electrodes to achieve electrochemical delithiation.

2. The method according to claim 1, characterized in that, The method for preparing the movable anode electrode includes the following steps: The black powder material, conductive agent, binder and solvent are mixed to form an electrode paste; The obtained electrode slurry is coated onto the current collector, leaving a blank current collector. Single-sided or double-sided coating is performed. After coating, the sample is dried to obtain the movable anode electrode. The movable anode sheet is wound on both sides of an electric unwinding machine and an electric winding machine, respectively; The black powder material is a retired lithium-ion battery material. The black powder material includes one or more of lithium iron phosphate, graphite, ternary materials, lithium cobalt oxide, and lithium manganese oxide.

3. The method according to claim 2, characterized in that, The conductive agent is at least one of acetylene black, conductive carbon black, carbon nanotubes, and graphene. The adhesive is at least one of polyvinylidene fluoride, polyacrylic acid, styrene-butadiene rubber, sodium carboxymethyl cellulose, and polytetrafluoroethylene; The solvent is at least one of N-methylpyrrolidone and water; The current collector is at least one of carbon-based material, titanium mesh, titanium foil, nickel foam, and aluminum foil; The drying temperature is 60~120℃; The area loading of black powder material coated on the current collector is 1~50 mg·cm. -2 .

4. The method according to claim 1, characterized in that, The electric unwinder is located upstream of the electrolytic cell; The electric winding machine is located downstream of the cleaning mechanism; The movable anode sheet is unwound by the electric unwinding machine and then sequentially conveyed to the electrolytic cell and cleaning mechanism before being wound up in the electric rewinding machine.

5. The method according to claim 1, characterized in that, The electrochemical delithiation device also includes a guiding component; The guide assembly includes a first guide assembly and a second guide assembly. The first guide assembly includes a plurality of first guide elements, and the second guide assembly includes a plurality of second guide elements. All adjacent first guide elements have the same height, and all adjacent second guide elements have the same height. The first guide component is positioned higher than the second guide component. The movable anode plate can be moved horizontally by continuously bypassing the first guide component or continuously bypassing the second guide component. The movable anode plate can be moved vertically or tilted by alternately bypassing the first guide component and the second guide component.

6. The method according to claim 1, characterized in that, The cathode electrode is one or more of Pt-based material electrodes and metal-doped carbon-based electrodes; The Pt-based material electrode is selected from one or more of Pt sheets, Pt meshes, Pt wires, and porous electrodes loaded with nano-Pt or Pt-based composite materials. The electrolytic cell is selected from one or more of the following: cuboid electrolytic cell, H-type electrolytic cell, and cylindrical electrolytic cell; The electrolyte is at least one of the following: Na2SO4 aqueous solution, Na2CO3 aqueous solution, NaCl aqueous solution, KCl aqueous solution, K2SO4 aqueous solution, NaNO3 aqueous solution, and KNO3 aqueous solution.

7. The method according to claim 1, characterized in that, The electrolytic cell is equipped with an agitator, which is used to promote mass transfer of the electrolyte, lithium removal reaction on the anode side, and oxygen reduction reaction on the cathode side.

8. The method according to claim 1, characterized in that, Following step (3), the following step (4) is also included: (4) Collect the lithium-ion-rich electrolyte from the electrolytic cell and the lithium-containing solution from the cleaning mechanism, concentrate them, and extract lithium.

9. The method according to claim 1, characterized in that, The electrical signal is applied in one of the following ways: constant voltage, constant current, or alternating constant current and constant voltage.

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