A lithium replenishment method, an electrochemical lithium replenishment system and its application

Abstract

This invention provides a lithium replenishment method, an electrochemical lithium replenishment system, and its application. The electrochemical lithium replenishment system includes at least one lithium plating device. The lithium plating device includes a lithium plating pool and an external circuit. A lithium source is disposed in the lithium plating pool and connected to a porous electrode. A roller is disposed opposite one surface of the porous electrode. The external circuit electrically connects the porous electrode and the roller. One surface of the electrode is in contact with the surface of the roller, and the other surface of the electrode faces the porous electrode. The presence of the external circuit and the porous electrode in this invention enables lithium ions to be uniformly transported to the electrode, achieving a highly efficient, uniform, and controllable lithium replenishment effect. The composition of the plating solution in the lithium plating pool can be adjusted according to actual production needs to form an SEI film with controllable structure and composition.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, and relates to an electrochemical lithium replenishment system device, and more particularly to a lithium replenishment method, an electrochemical lithium replenishment system device, and their applications. Background Technology

[0002] Lithium-ion batteries have become one of the most important energy storage methods in the world today due to their high energy density and long cycle life. However, during the first charge of a lithium-ion battery, the formation of a solid electrolyte interphase (SEI) film and the partial irreversible lithium embedding in the negative electrode result in some lithium being unable to be recycled, affecting the energy density of the lithium-ion battery. Currently, the most important way to improve initial efficiency and reduce irreversible lithium loss is lithium replenishment technology, which utilizes lithium pre-deposited into the negative electrode to reduce lithium loss from the positive electrode.

[0003] Various pre-lithiation strategies have been developed, such as external electrochemical pre-lithiation, chemical pre-lithiation, and lithium salt-assisted pre-lithiation. Among them, contact pre-lithiation has the greatest potential for industrial development, which involves incorporating a lithium metal source into the negative electrode and then subjecting it to an internal short-circuit micro-corrosion reaction in the electrolyte. However, it must be noted that not all lithium metal sources participate in the pre-lithiation reaction, and the utilization rate of the lithium source is often less than 65%. The amount and uniformity of lithium deposition, as well as the process, cannot be well controlled, affecting the efficiency and effectiveness of lithium replenishment. The remaining unconverted lithium source has lost its electronic conductivity and is considered "dead lithium," accumulating at the negative electrode interface and hindering the diffusion and mass transfer of lithium ions, leading to increased battery polarization and lithium plating. At the same time, conventional pre-lithiation struggles to form a stable and controllable SEI film, and the performance of the negative electrode cannot be effectively guaranteed after lithium replenishment.

[0004] CN109755474A discloses a method and apparatus for replenishing lithium in lithium-ion battery anode materials, relating to the field of lithium-ion battery technology. The method includes the following steps: using electrode materials from spent lithium batteries or lithium-containing electrolyte as a lithium source, obtaining a lithium-plated metal sheet through electroplating; using the lithium-plated metal sheet as a lithium source, forming a first electrolytic cell with the lithium battery anode material, electrolyte, and separator; and electrochemically replenishing lithium in the lithium-ion anode material through constant current charging and discharging. However, this method and apparatus for replenishing lithium in lithium-ion battery anode materials suffers from low lithium source utilization, inability to control the amount and uniformity of lithium deposition, and poor efficiency and effectiveness in replenishing lithium.

[0005] CN111987288A discloses a method and application for in-situ lithium replenishment of electrodes in lithium-ion energy storage devices. The method involves placing the electrode sheet within the vacuum chamber of a vapor deposition apparatus, and under vacuum conditions, using an evaporating lithium source to vacuum vapor deposit lithium onto the surface of the electrode sheet carrying the active electrode material, forming a vapor-deposited lithium layer. After vacuum vapor deposition, while maintaining a pressure ≤1 Pa within the vacuum chamber, high-purity nitrogen gas is introduced into the vacuum chamber to nitrid the vapor-deposited lithium layer, generating lithium nitride in situ on the electrode sheet surface. The high-purity nitrogen gas has a purity of not less than 99.999%. However, this method for in-situ lithium replenishment of electrodes in lithium-ion energy storage devices is relatively complex, requires demanding experimental conditions, and is costly, hindering its large-scale application.

[0006] CN109103419A discloses a lithium-ion battery negative electrode for lithium replenishment and its preparation method. The method involves pre-lithiating the negative electrode material or electrode sheet, and coating the surface of the pre-lithiated electrode with an organic thin film layer. This organic thin film layer is composed of an electrolyte lithium salt dissolved in an organic solvent. This invention forms an organic thin film layer on the surface of the pre-lithiated electrode by coating the surface with an organic coating solution made of an electrolyte lithium salt. However, this lithium-ion battery negative electrode for lithium replenishment does not form a stable and controllable SEI film, and the performance of the negative electrode after lithium replenishment cannot be guaranteed.

[0007] Currently available lithium replenishment methods and electrochemical lithium replenishment systems all have certain drawbacks, including low lithium source utilization, uncontrollable lithium deposition amount and uniformity, poor lithium replenishment effect, difficulty in forming a stable and controllable SEI film, inability to effectively guarantee the performance of the negative electrode after lithium replenishment, and high cost. Therefore, developing a novel lithium replenishment method and electrochemical lithium replenishment system is crucial. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a lithium replenishment method, an electrochemical lithium replenishment system, and its applications. The external circuit and porous electrodes of this invention enable the uniform transfer of lithium ions to the electrode plates, achieving efficient, uniform, and controllable lithium replenishment. The composition of the plating solution in the lithium plating pool can be adjusted according to different process requirements, forming an SEI film with controllable structure and composition to meet the needs of different negative electrode systems, thereby optimizing battery composition and performance. The electrochemical lithium replenishment system provides uniform and stable lithium deposition, a highly controllable process, and the ability to pre-form a dense and stable SEI film, significantly improving lithium replenishment efficiency and effectiveness. This provides a novel solution for commercial lithium replenishment and has high practical value.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides an electrochemical lithium replenishment system device, the electrochemical lithium replenishment system device comprising at least one lithium plating device;

[0011] The lithium plating device includes a lithium plating pool and an external circuit. A lithium source is provided in the lithium plating pool. The lithium source is connected to a porous electrode. A roller is provided opposite to one side surface of the porous electrode. The external circuit is electrically connected to the porous electrode and the roller. One side surface of the electrode is in contact with the surface of the roller, and the other side surface of the electrode faces the porous electrode.

[0012] Lithium in the lithium source loses electrons under the action of an electric field to become lithium ions and enters the electrolyte. Under the action of an electric field, the lithium ions move to the surface of the porous electrode and, under the action of an external circuit, gain electrons on the surface of the electrode to become metallic lithium. The metallic lithium is deposited on the surface of the electrode, embedded in the active material lattice of the electrode to form an intercalation compound, or reacts with the active material of the electrode to form a lithium alloy, thereby completing the pre-lithiation of the electrode.

[0013] The presence of the external circuit and porous electrode described in this invention allows lithium ions to be uniformly transported to the electrode, achieving efficient, uniform, and controllable lithium replenishment. The composition of the plating solution in the lithium plating pool can be adjusted according to different process production needs to form an SEI film with controllable structure and composition, so as to meet the needs of negative electrode sheets of different systems, thereby optimizing battery composition and performance.

[0014] The electrochemical lithium replenishment system of this invention exhibits uniform and stable lithium deposition, highly controllable process, and the ability to pre-form a dense and stable SEI film, which greatly improves lithium replenishment efficiency and effect, providing a brand-new solution for commercial lithium replenishment and possessing high practical value.

[0015] As a preferred embodiment of the present invention, the porous electrode has a semi-circular structure.

[0016] The porous electrode of the present invention has a semi-circular structure, and the semi-circular porous electrode matches the arc shape of the roller surface.

[0017] Preferably, the radial distance between the side surface of the porous electrode opposite to the roller and the outer surface of the roller is equal everywhere.

[0018] The radial distance between the side surface of the porous electrode relative to the roller and the outer surface of the roller is equal everywhere in this invention. A regular electric field can be formed between the porous electrode and the roller, so that lithium ions can be uniformly gathered on the surface of the carbon / silicon negative electrode under the action of the electric field, reduced and embedded in the inside of the negative electrode to achieve pre-lithiation, and achieve efficient, uniform and controllable lithium replenishment effect.

[0019] Preferably, the lithium plating tank is provided with a lithium source, a porous electrode and a roller arranged sequentially from bottom to top, with the lithium source located at the bottom of the lithium plating tank.

[0020] Preferably, the lithium source is in direct contact and / or electrically connected to the porous electrode.

[0021] Preferably, the roller is a metal roller.

[0022] The roller described in this invention is conductive, and the external circuit is electrically connected to the porous electrode and the roller, which enables an electric field to be formed between the roller and the porous electrode.

[0023] Preferably, agitators are provided on both sides of the roller.

[0024] The stirring device described in this invention is used to stir the electrolyte, thereby accelerating ion diffusion, preventing uneven lithium deposition caused by lithium ion enrichment, and improving lithium plating efficiency.

[0025] As a preferred embodiment of the present invention, the electrochemical lithium replenishment system further includes a transmission device, and several lithium plating devices are connected through the transmission device, with the electrode sheets passing between the transmission devices.

[0026] Preferably, the transmission device includes a plurality of rollers.

[0027] As a preferred embodiment of the present invention, the lithium plating apparatus further includes a relaxation electrolytic cell, which is connected to the lithium plating cell via a transmission device; the electrode sheets are routed between the transmission devices, and after being transported out of the lithium plating cell by the transmission devices, the electrode sheets enter the relaxation electrolytic cell.

[0028] In this invention, after the electrode completes electrochemical lithium intercalation in the lithium plating pool, it is immersed in a relaxation electrolytic cell for a period of time, so that the metallic lithium that may exist on the surface of the electrode is further deposited into the interior of the electrode, thus avoiding the presence of bare metallic lithium on the surface.

[0029] In a preferred embodiment of the present invention, the electrochemical lithium replenishment system includes two lithium plating devices, referred to as a first lithium plating device and a second lithium plating device, respectively. The first and second lithium plating devices have identical structures and are connected by a transmission device. Electrodes are routed between the transmission devices, and after exiting the first lithium plating device, the electrodes enter the second lithium plating device.

[0030] The electrochemical lithium replenishment system of the present invention includes two lithium plating devices, which can achieve double-sided lithium plating of the electrode, eliminating the complicated disassembly process and improving the uniformity of lithium plating.

[0031] As a preferred technical solution of the present invention, the transmission device includes a steering roller, which is disposed between the first lithium plating device and the second lithium plating device;

[0032] After lithium plating is performed on one side of the electrode in the first lithium plating device, the electrode passes around the steering roller. With the cooperation of the steering roller and the transmission device, the electrode flips over, and the other side of the electrode faces the porous electrode for lithium plating.

[0033] As a preferred embodiment of the present invention, the electrochemical lithium replenishment system further includes a drying device, which is connected to the second lithium plating device via a transmission device; the electrode is routed between the transmission devices, and after being transmitted from the second lithium plating device by the transmission device, the electrode enters the drying device.

[0034] The electrochemical lithium replenishment system device of the present invention is used to dry the electrode sheets after lithium replenishment, so as to facilitate the collection and utilization of the electrode sheets.

[0035] In a second aspect, the present invention provides a lithium replenishment method for the electrochemical lithium replenishment system device described in the first aspect, the lithium replenishment method comprising:

[0036] Under the action of the external circuit, an electric field is formed between the porous electrode and the roller. The lithium in the lithium source loses electrons under the action of the electric field and becomes lithium ions, which enter the electrolyte. The lithium ions move to the surface of the porous electrode under the action of the electric field and gain electrons on the surface of the electrode under the action of the external circuit, becoming metallic lithium. The metallic lithium is deposited on the surface of the electrode, embedded in the active material lattice of the electrode to form an intercalation compound, or reacts with the active material of the electrode to form a lithium alloy, thereby completing the pre-lithiation of the electrode.

[0037] The lithium replenishment method described in this invention differs from traditional lithium replenishment approaches. Through an electrochemical method, a uniform pre-film can be formed to complete lithium plating. The prepared electrode has the advantages of highly controllable lithium loading, strong uniformity, and adjustable SEI film.

[0038] As a preferred embodiment of the present invention, the lithium replenishment method includes:

[0039] The electrode sheet is conveyed by a transmission device to the surface of the roller in the first lithium plating device. Under the action of the external circuit, an electric field is formed between the semi-annular porous electrode and the roller. The lithium source first loses electrons to become lithium ions and enters the electrolyte. Then, under the action of the external circuit, it moves to the surface of the electrode sheet and gains electrons to become metallic lithium. The metallic lithium reacts with the electrode sheet to complete the pre-lithiation. The electrode sheet with metallic lithium deposited is conveyed by the transmission device out of the lithium plating pool and into the relaxation electrolytic cell. The metallic lithium deposited on the electrode sheet will further react with the active material on the electrode sheet completely. After immersing in the relaxation electrolytic cell, the electrode sheet is conveyed out of the relaxation electrolytic cell by the transmission device. After immersing in the relaxation electrolytic cell, the electrode sheet passes around the steering roller. With the cooperation of the steering roller and the transmission device, the electrode sheet flips and enters the second lithium plating device. The other side of the electrode sheet faces the semi-annular porous electrode for lithium plating. After lithium plating is completed, the electrode sheet is conveyed by the transmission device into the drying device for drying, completing the lithium replenishment.

[0040] Thirdly, the present invention provides an application of the electrochemical lithium replenishment system device described in the first aspect, wherein the electrochemical lithium replenishment system device is used for pre-lithiation of the negative electrode of a lithium-ion battery.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] The presence of the external circuit and porous electrode described in this invention allows lithium ions to be uniformly transported to the electrode, achieving efficient, uniform, and controllable lithium replenishment. The composition of the plating solution in the lithium plating pool can be adjusted according to different process production needs to form an SEI film with controllable structure and composition, so as to meet the needs of negative electrode sheets of different systems, thereby optimizing battery composition and performance.

[0043] The electrochemical lithium replenishment system of this invention exhibits uniform and stable lithium deposition, highly controllable process, and the ability to pre-form a dense and stable SEI film, which greatly improves lithium replenishment efficiency and effect, providing a brand-new solution for commercial lithium replenishment and possessing high practical value. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the electrochemical lithium replenishment system device in a specific embodiment of the present invention.

[0045] Wherein, 1-first lithium plating device; 2-second lithium plating device; 3-lithium plating pool; 4-external circuit; 5-lithium source; 6-porous electrode; 7-roller; 8-stirrer; 9-plating solution; 10-drying device; 11-relaxation electrolytic cell; 100-transmission device; 101-first roller; 102-second roller; 103-third roller; 104-fourth roller; 105-fifth roller; 106-directing roller; 107-sixth roller; 108-seventh roller; 109-eighth roller; 110-ninth roller; 111-tenth roller. Detailed Implementation

[0046] It should be understood that in the description of this invention, the terms "upper," "lower," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0047] It should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0048] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0049] In one specific embodiment, the present invention provides an electrochemical lithium replenishment system device, the electrochemical lithium replenishment system device including at least one lithium plating device;

[0050] like Figure 1 As shown, the lithium plating device includes a lithium plating pool 3 and an external circuit 4. A lithium source 5 is provided in the lithium plating pool 3. The lithium source 5 is connected to a porous electrode 6. A roller 7 is arranged opposite to one side surface of the porous electrode 6. The external circuit 4 is electrically connected to the porous electrode 6 and the roller 7. One side surface of the electrode is in contact with the surface of the roller 7, and the other side surface of the electrode faces the porous electrode 6.

[0051] The lithium in the lithium source 5 loses electrons under the action of an electric field and becomes lithium ions, which enter the electrolyte. The lithium ions move to the surface of the porous electrode 6 under the action of an electric field, and gain electrons on the surface of the electrode under the action of the external circuit 4 to become metallic lithium. The metallic lithium is deposited on the surface of the electrode, embedded in the active material lattice of the electrode to form an intercalation compound, or reacts with the active material of the electrode to form a lithium alloy, thereby completing the pre-lithiation of the electrode.

[0052] The presence of the external circuit 4 and the porous electrode 6 in this invention enables lithium ions to be uniformly transported to the electrode, achieving efficient, uniform, and controllable lithium replenishment. The composition of the plating solution 9 in the lithium plating pool 3 can be adjusted according to different process production needs to form an SEI film with controllable structure and composition, so as to meet the needs of negative electrode sheets of different systems, thereby optimizing battery composition and performance.

[0053] The electrochemical lithium replenishment system of this invention exhibits uniform and stable lithium deposition, highly controllable process, and the ability to pre-form a dense and stable SEI film, which greatly improves lithium replenishment efficiency and effect, providing a brand-new solution for commercial lithium replenishment and possessing high practical value.

[0054] Furthermore, the porous electrode 6 has a semi-circular structure.

[0055] The porous electrode 6 of the present invention has a semi-circular structure, and the semi-circular porous electrode 6 matches the arc shape of the surface of the roller 7.

[0056] Furthermore, the radial distance between the side surface of the porous electrode 6 relative to the roller 7 and the outer surface of the roller 7 is equal everywhere.

[0057] In this invention, the radial distance between the side surface of the porous electrode 6 relative to the roller 7 and the outer surface of the roller 7 is equal everywhere. A regular electric field can be formed between the porous electrode 6 and the roller 7, so that lithium ions can be uniformly gathered on the surface of the carbon / silicon negative electrode under the action of the electric field, reduced and embedded in the interior of the negative electrode to achieve pre-lithiation, and achieve efficient, uniform and controllable lithium replenishment effect.

[0058] Furthermore, the lithium plating pool 3 is provided with a lithium source 5, a porous electrode 6 and a roller 7 arranged sequentially from bottom to top, with the lithium source 5 located at the bottom of the lithium plating pool 3.

[0059] Furthermore, the lithium source 5 is in direct contact and / or electrically connected to the porous electrode 6.

[0060] Furthermore, the roller 7 is a metal roller.

[0061] The roller 7 described in this invention is conductive, and the external circuit 4 is electrically connected to the porous electrode 6 and the roller 7, which enables an electric field to be formed between the roller 7 and the porous electrode 6.

[0062] Furthermore, agitators 8 are respectively provided on both sides of the roller 7.

[0063] The stirring device described in this invention is used to stir the electrolyte, thereby accelerating ion diffusion, preventing uneven lithium deposition caused by lithium ion enrichment, and improving lithium plating efficiency.

[0064] Furthermore, the electrochemical lithium replenishment system also includes a transmission device 100, and several of the lithium plating devices are connected through the transmission device 100, with the electrode sheets passing between the transmission devices 100.

[0065] For example, the transmission device 100 includes a first roller 101, a second roller 102, a third roller 103, a fourth roller 104, a fifth roller 105, a sixth roller 107, a seventh roller 108, an eighth roller 109, a ninth roller 110, and a tenth roller 111.

[0066] Furthermore, the lithium plating apparatus also includes a relaxation electrolytic cell 11, which is connected to the lithium plating cell 3 via a transmission device 100; the electrode sheets are routed between the transmission devices 100, and after being transmitted out of the lithium plating cell 3 by the transmission devices 100, the electrode sheets enter the relaxation electrolytic cell 11.

[0067] In this invention, after the electrode completes electrochemical lithium intercalation in the lithium plating pool 3, it will be immersed in the relaxation electrolytic cell 11 for a period of time, so that the metallic lithium that may exist on the surface of the electrode will be further deposited into the interior of the electrode, thus avoiding the presence of bare metallic lithium on the surface.

[0068] Furthermore, the electrochemical lithium replenishment system includes two lithium plating devices, referred to as the first lithium plating device 1 and the second lithium plating device 2, respectively. The first lithium plating device 1 and the second lithium plating device 2 have identical structures and are connected by a transmission device 100. The electrode moves between the transmission devices 100, and after being conveyed out of the first lithium plating device 1, the electrode enters the second lithium plating device 2.

[0069] The electrochemical lithium replenishment system of the present invention includes two lithium plating devices, which can achieve double-sided lithium plating of the electrode, eliminating the complicated disassembly process and improving the uniformity of lithium plating.

[0070] Furthermore, the transmission device 100 includes a steering roller 106, which is disposed between the first lithium plating device 1 and the second lithium plating device 2;

[0071] After lithium plating is performed on one side of the electrode in the first lithium plating device 1, the electrode passes around the steering roller 106. With the cooperation of the steering roller 106 and the transmission device 100, the electrode flips over and the other side of the electrode faces the porous electrode 6 for lithium plating.

[0072] Furthermore, the electrochemical lithium replenishment system also includes a drying device 10, which is connected to the second lithium plating device 2 via a transmission device 100; the electrode sheets are routed between the transmission devices 100, and after being transmitted from the second lithium plating device 2 by the transmission devices 100, the electrode sheets enter the drying device 10.

[0073] The electrochemical lithium replenishment system device of the present invention is used to dry the electrode sheets after lithium replenishment, so as to facilitate the collection and utilization of the electrode sheets.

[0074] In this invention, the first roller 101 is located above and to the left of the lithium plating pool 3 in the first lithium plating device 1, and the electrode passes around the first roller 101 to reach the surface of the roller 7 of the first lithium plating device 1; the second roller 102 is located above and to the left of the relaxation electrolytic cell 11, and the electrode passes around the second roller 102 to reach the inside of the relaxation electrolytic cell 11; the third roller 103 and the fourth roller 104 are located on the same horizontal plane at the bottom of the relaxation electrolytic cell 11; the fifth roller 105 is located above and to the right of the relaxation electrolytic cell 11, and the fifth roller 105 and the steering roller 106 are located on the same horizontal plane, and the electrode passes around the fifth roller 105 and the steering roller 106 to enter the relaxation electrolytic cell 11. The second lithium plating device 2; the sixth roller 107 is located above the right of the relaxation electrolytic cell in the second lithium plating device 2, and the electrode passes around the sixth roller 107 to enter the relaxation electrolytic cell in the second lithium plating device 2; the seventh roller 108 and the eighth roller 109 are located on the same horizontal plane at the bottom of the relaxation electrolytic cell in the second lithium plating device 2; the ninth roller 110 is located above the left of the relaxation electrolytic cell in the second lithium plating device 2, and the tenth roller 111 is located below the second lithium plating device 2. The ninth roller 110 and the tenth roller 111 are located on the same vertical plane, and the electrode passes around the ninth roller 110 and the tenth roller 111 to enter the drying device 10.

[0075] In another specific embodiment, the present invention provides a lithium replenishment method for an electrochemical lithium replenishment system, the lithium replenishment method comprising:

[0076] Under the action of the external circuit 4, an electric field is formed between the porous electrode 6 and the roller 7. The lithium in the lithium source 5 loses electrons and becomes lithium ions under the action of the electric field, and enters the electrolyte. The lithium ions move to the surface of the porous electrode 6 under the action of the electric field, and gain electrons on the surface of the electrode under the action of the external circuit 6 to become metallic lithium. The metallic lithium is deposited on the surface of the electrode, embedded in the active material lattice of the electrode to form an intercalation compound, or reacts with the active material of the electrode to form a lithium alloy, thereby completing the pre-lithiation of the electrode.

[0077] The lithium replenishment method described in this invention differs from traditional lithium replenishment approaches. Through an electrochemical method, a uniform pre-film can be formed to complete lithium plating. The prepared electrode has the advantages of highly controllable lithium loading, strong uniformity, and adjustable SEI film.

[0078] Furthermore, the lithium replenishment method includes:

[0079] The electrode sheet is conveyed by the transmission device 100 to the surface of the roller 7 in the first lithium plating device 1. Under the action of the external circuit 4, an electric field is formed between the semi-annular porous electrode 6 and the roller 7. The lithium source 5 is first deposited on the surface of the semi-annular porous electrode 6 and loses electrons to obtain lithium ions under the action of the external circuit 4. The lithium ions migrate to the surface of the roller 7 facing the semi-annular porous electrode 6 under the action of the electric field. The electrode sheet with lithium deposited is conveyed by the transmission device 100 out of the lithium plating pool 3 and into the relaxation electrolysis pool 11. After being immersed in the relaxation electrolysis pool 11, the electrode sheet is conveyed out of the relaxation electrolysis pool 11 by the transmission device 100.

[0080] The electrode sheet is conveyed by the transmission device 100 to the surface of the roller 7 in the first lithium plating device 1. Under the action of the external circuit 4, an electric field is formed between the semi-annular porous electrode 6 and the roller 7. The lithium source 5 first loses electrons to become lithium ions and enters the electrolyte. Then, under the action of the external circuit, it moves to the surface of the electrode sheet and gains electrons to become metallic lithium. The metallic lithium reacts with the electrode sheet to complete the pre-lithiation. The electrode sheet with metallic lithium deposited is conveyed by the transmission device 100 out of the lithium plating pool 3 and enters the relaxation electrolytic cell 11. The electrode surface is deposited with... The lithium metal will further react completely with the active material on the electrode. After the electrode is immersed in the relaxation electrolytic cell 11, it is conveyed out of the relaxation electrolytic cell 11 by the transmission device 100. After the electrode is immersed in the relaxation electrolytic cell 11, it passes around the steering roller 106. With the cooperation of the steering roller 106 and the transmission device 100, the electrode flips and enters the second lithium plating device 2. The other side of the electrode faces the porous electrode 6 with a semi-annular structure for lithium plating. After the lithium plating is completed, the electrode is conveyed by the transmission device 100 into the drying device 10 for drying, thus completing the lithium replenishment.

[0081] In another specific embodiment, the present invention provides an application of the electrochemical lithium replenishment system device described in the first aspect, the electrochemical lithium replenishment system device being used for pre-lithiation of the negative electrode of a lithium-ion battery.

[0082] Application examples

[0083] The parameters for various experimental conditions in the actual operation of the electrochemical lithium replenishment system of this invention are as follows:

[0084] 1. Electrolyte composition (commercial lithium-ion battery electrolyte);

[0085] Element EC EMC DEC VC LiPF6 Proportion 30wt% 40wt% 15wt% 1.5wt% 13.5wt%

[0086] 2. External voltage is 3V;

[0087] 3. The electrolysis time is t min, the electrode conveying speed is vm / min, the electrode length is 1dm, and the electrode width is d dm. Then l=θπR / 180, and there exists a relationship t=θπR / (180v), where θ (°) is the angle between the center of the roller 7 and the two ends of the semi-annular porous electrode 6, and R (dm) is the radius of the roller 7.

[0088] 4. According to the electroplating formula δ=100KDtη / (60γ) (where δ is the film thickness in μm, K is the electrochemical equivalent of lithium 0.259g / (A·h), and D is the current density in A / dm²), 2 t is the electroplating time in minutes, η is the current efficiency, and γ is the density of lithium (0.534 g / cm³). 3 Substituting the time t, we get the coating thickness δ=100KDθπRη / (10800vγ)=0.235θRη·D / vμm.

[0089] Total lithium plating charge M = γ·δ·d·l / N·F = 100Ddl 2 η / (60v)=(θR) 2 dη / 1181.8·D / vmAh. By controlling the current and the tape feed rate, the value of D and v are changed, thus affecting the thickness of the coating, i.e., the Li deposited on the electrode. + The content of.

[0090] The electrode sheets after lithium replenishment by the electrochemical lithium replenishment system device described in this invention exhibit a uniform golden-yellow color, and the lithium replenishment results of the negative electrode sheet are relatively stable and highly consistent.

[0091] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. An electrochemical lithium replenishment system device, characterized in that, The electrochemical lithium replenishment system includes at least one lithium plating device; The lithium plating apparatus includes a lithium plating pool and an external circuit. A lithium source is provided in the lithium plating pool and is connected to a porous electrode. A metal roller is disposed opposite one side surface of the porous electrode. A stirrer is disposed on both sides of the metal roller. The external circuit is electrically connected to the porous electrode and the metal roller. The radial distance between the side surface of the porous electrode opposite the metal roller and the outer surface of the metal roller is equal everywhere. One side surface of the electrode sheet is in contact with the surface of the metal roller, and the other side surface of the electrode sheet faces the porous electrode. The lithium plating apparatus further includes a relaxation electrolytic cell, which is connected to the lithium plating cell via a transmission device; the electrode is routed between the transmission devices, and after being transported out of the lithium plating cell by the transmission devices, the electrode enters the relaxation electrolytic cell.

2. The electrochemical lithium replenishment system device according to claim 1, characterized in that, The porous electrode has a semi-circular structure.

3. The electrochemical lithium replenishment system device according to claim 1, characterized in that, The lithium plating tank is arranged from bottom to top with a lithium source, a porous electrode and a roller, and the lithium source is located at the bottom of the lithium plating tank.

4. The electrochemical lithium replenishment system device according to claim 1, characterized in that, The lithium source is in direct contact and / or electrically connected to the porous electrode.

5. The electrochemical lithium replenishment system device according to claim 1, characterized in that, The electrochemical lithium replenishment system also includes a transmission device, and several of the lithium plating devices are connected through the transmission device, with the electrode sheets passing between the transmission devices.

6. The electrochemical lithium replenishment system device according to claim 1, characterized in that, The transmission device includes several rollers.

7. The electrochemical lithium replenishment system device according to claim 1, characterized in that, The electrochemical lithium replenishment system includes two lithium plating devices, referred to as the first lithium plating device and the second lithium plating device, respectively. The first lithium plating device and the second lithium plating device have the same structure and are connected by a transmission device. The electrode moves between the transmission devices and is conveyed out of the first lithium plating device and then into the second lithium plating device.

8. The electrochemical lithium replenishment system device according to claim 1, characterized in that, The transmission device includes a steering roller, which is disposed between the first lithium plating device and the second lithium plating device; After lithium plating is performed on one side of the electrode in the first lithium plating device, the electrode passes around the steering roller. With the cooperation of the steering roller and the transmission device, the electrode flips over, and the other side of the electrode faces the porous electrode for lithium plating.

9. The electrochemical lithium replenishment system device according to claim 1, characterized in that, The electrochemical lithium replenishment system also includes a drying device, which is connected to the second lithium plating device via a transmission device; the electrode is routed between the transmission devices, and after being transmitted from the second lithium plating device by the transmission device, the electrode enters the drying device.

10. A lithium replenishment method using the electrochemical lithium replenishment system device according to any one of claims 1-9, characterized in that, The lithium replenishment method includes: Under the action of the external circuit, an electric field is formed between the porous electrode and the roller. The lithium in the lithium source loses electrons under the action of the electric field and becomes lithium ions, which enter the electrolyte. The lithium ions move to the surface of the porous electrode under the action of the electric field and gain electrons on the surface of the electrode under the action of the external circuit, becoming metallic lithium. The metallic lithium is deposited on the surface of the electrode, embedded in the active material lattice of the electrode to form an intercalation compound, or reacts with the active material of the electrode to form a lithium alloy, thereby completing the pre-lithiation of the electrode.

11. The lithium replenishment method according to claim 10, characterized in that, The lithium replenishment method includes: The electrode sheet is conveyed by a transmission device to the surface of the roller in the first lithium plating device. Under the action of the external circuit, an electric field is formed between the semi-annular porous electrode and the roller. The lithium source first loses electrons to become lithium ions and enters the electrolyte. Then, under the action of the external circuit, it moves to the surface of the electrode sheet and gains electrons to become metallic lithium. The metallic lithium reacts with the electrode sheet to complete the pre-lithiation. The electrode sheet with metallic lithium deposited is conveyed by the transmission device out of the lithium plating pool and into the relaxation electrolytic cell. The metallic lithium deposited on the electrode sheet will further react with the active material on the electrode sheet completely. After immersing in the relaxation electrolytic cell, the electrode sheet is conveyed out of the relaxation electrolytic cell by the transmission device. After immersing in the relaxation electrolytic cell, the electrode sheet passes around the steering roller. With the cooperation of the steering roller and the transmission device, the electrode sheet flips and enters the second lithium plating device. The other side of the electrode sheet faces the semi-annular porous electrode for lithium plating. After lithium plating is completed, the electrode sheet is conveyed by the transmission device into the drying device for drying, completing the lithium replenishment.

12. The application of the electrochemical lithium replenishment system device according to any one of claims 1-9, characterized in that, The electrochemical lithium replenishment system is used for the pre-lithiation of the negative electrode of a lithium-ion battery.

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