A negative electrode plate lithium coating system device and lithium coating method thereof

Abstract

The present invention provides a negative electrode sheet lithium coating system and a lithium coating method thereof. The system includes a lithium coating device and a cleaning device. The lithium coating device includes a shell injected with an electrolyte, at least one guide roller is arranged in the shell, a lithium source immersed in the electrolyte is also arranged in the shell, a feed conductive roller is arranged at the feed end of the shell, the feed conductive roller is electrically connected to the lithium source, a current regulator is arranged on the line where the feed conductive roller is electrically connected to the lithium source, the negative electrode sheet bypasses the feed conductive roller and the guide roller, and is immersed in the electrolyte, and the negative electrode sheet is electrically connected to the lithium source through the feed conductive roller for lithium coating; the cleaning device is provided with an ultrasonic generator, and the negative electrode sheet after lithium coating enters the cleaning device for cleaning. The present invention makes the negative electrode sheet after lithium coating be uniformly and stably coated with lithium, and has the characteristics of simple structure, adjustable lithium coating thickness, and easy industrialization.

Description

Technical Field

[0001] The present invention belongs to the field of battery technology and relates to lithium coating of negative electrode plates, and in particular to a negative electrode plate lithium coating system device and a lithium coating method thereof. Background Art

[0002] Lithium-ion batteries are increasingly used in consumer electronics and new energy vehicles. The energy density and cycle life of batteries are important concerns for current lithium-ion batteries. By pre-coating the negative electrode with lithium, the battery's initial charging efficiency, energy density and cycle life can be improved.

[0003] When the battery made of negative electrode pieces is activated and recycled, the side reaction will cause the loss of part of the lithium source in the electrolyte, resulting in low initial efficiency of the battery and rapid decline in the battery's cycle performance. The negative electrode is mainly coated with lithium by adding positive electrode lithium supplement additives and physically coating the negative electrode with lithium. This method can effectively improve the battery's cycle performance and initial efficiency, but the negative electrode piece is unevenly coated with lithium, which can easily lead to lithium precipitation during the use of the battery.

[0004] CN209169291U discloses a pole piece pre-lithium device, which includes: a spraying device, which is used to spray pre-lithium powder toward the pole piece, and the spraying device includes: a storage tank; a nozzle, which is connected to the storage tank to spray pre-lithium powder toward the pole piece, and a pressure adjustment device for adjusting the spray pressure of the nozzle is provided between the nozzle and the storage tank; an inert gas protection device, which is used to prevent lithium powder from contacting with air when spraying pre-lithium powder; a pole piece retracting device; a rolling device is provided downstream of the nozzle to roll the pole piece sprayed with pre-lithium powder. The pole piece pre-lithium device can spray pre-lithium powder onto the pole piece, so that a lithium powder layer is formed on the surface of the pole piece. However, the use of spraying still has the problem of uneven and unstable lithium coating.

[0005] CN209487602U discloses a device for pre-lithiation of lithium-ion battery negative electrode sheets in steps, the device comprises at least three pre-lithiation units, a first pre-lithiation unit, a second pre-lithiation unit and a final pre-lithiation unit, for pre-lithiation of lithium-ion battery negative electrode sheets in steps. According to the order of the pre-lithiation process of lithium-ion battery negative electrode sheets in steps, the first pre-lithiation unit and the second pre-lithiation unit are arranged in sequence, and the remaining pre-lithiation units are arranged after the second pre-lithiation unit, wherein the final pre-lithiation unit is arranged at the last position. The device pre-lithiates the negative electrode sheets of lithium-ion batteries in steps, and multiple pre-lithiations ensure uniform and accurate lithium replenishment of the negative electrode sheets of lithium-ion batteries. However, multiple pre-lithiations in steps make the process complicated and not easy to industrialize.

[0006] CN209217136U discloses a continuous pre-lithiation device for lithium-ion battery electrodes, comprising a battery pole piece and a metal lithium belt, wherein the battery pole piece is connected to a pre-lithiation zone via a humidification treatment box filled with an organic solvent containing lithium salt, and the metal lithium belt is connected to the pre-lithiation zone via a metal lithium belt conveyor. In the pre-lithiation zone, the battery pole piece is in close contact with the metal lithium belt, the metal lithium belt passing through the pre-lithiation zone is connected to a metal lithium belt recovery device, the battery pole piece passing through the pre-lithiation zone is connected to a washing box filled with an organic solvent containing lithium salt via a connecting roller, the battery pole piece passing through the washing box is connected to a drying treatment box, and the battery pole piece passing through the drying treatment box is connected to a shaping roller.

[0007] Existing lithium coating devices all have problems of complex structure, uneven or unstable lithium coating. Therefore, how to ensure that the lithium coating device has a simple structure and a simple process while also coating the electrode with lithium uniformly and stably has become a problem that urgently needs to be solved. Summary of the invention

[0008] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a negative electrode plate lithium coating system device and a lithium coating method thereof, wherein the negative electrode plate is connected to a lithium source to form a primary battery, and the current between the negative electrode plate and the lithium source is adjusted by a current regulator to coat the negative electrode plate with lithium. The lithium coating method is simple and does not require an external power supply. After the lithium coating, the negative electrode plate is ultrasonically cleaned to ensure that the lithium coating is uniform and stable. The present invention has the characteristics of simple structure, adjustable lithium coating thickness and easy industrialization.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] In the first aspect, the present invention provides a negative electrode plate lithium coating system device, the system device includes a lithium coating device and a cleaning device, the lithium coating device includes a shell injected with an electrolyte, at least one guide roller is arranged in the shell, a lithium source immersed in the electrolyte is also arranged in the shell, a feeding end of the shell is provided with a feeding conductive roller, the feeding conductive roller is electrically connected to the lithium source, a current regulator is arranged on the line electrically connected between the feeding conductive roller and the lithium source, the negative electrode plate bypasses the feeding conductive roller and the guide roller, and is immersed in the electrolyte, and the negative electrode plate is electrically connected to the lithium source through the feeding conductive roller for lithium coating; the cleaning device is provided with an ultrasonic generator, and the negative electrode plate after lithium coating enters the cleaning device for cleaning.

[0011] In the present invention, the negative electrode plate is connected to a lithium source to form a primary battery, and the current between the negative electrode plate and the lithium source is adjusted by a current regulator. No external power source is required to electrochemically coat the plate with lithium, and the lithium coating on both sides of the negative electrode plate is uniform and stable. Furthermore, by adjusting the current size and time, the amount of lithium coating can be accurately controlled. In addition, during the electrochemical lithium coating process, side reactions occur simultaneously at the interface where the negative electrode plate contacts the electrolyte to form an SEI film, which can reduce the consumption of active lithium in the electrolyte and the positive electrode material during battery formation, and effectively improve the initial coulombic efficiency and later cycle performance of the battery. After ultrasonic cleaning, the lithium-coated negative electrode plate of the present invention is uniformly and stably coated with lithium, and has the characteristics of simple structure, adjustable lithium coating thickness, and easy industrialization.

[0012] It should be noted that the present invention does not impose any specific requirements or special limitations on the electrical connection method, and those skilled in the art may reasonably select the electrical connection method according to operational requirements, for example, the electrical connection is a wire connection.

[0013] As a preferred technical solution of the present invention, the system device also includes a unwinding device, a drying device and a winding device. Along the processing direction of the negative electrode sheet, the system device includes an unwinding device, a lithium coating device, a cleaning device, a drying device and a winding device arranged in sequence.

[0014] Preferably, a cleaning agent is injected into the cleaning device.

[0015] Preferably, the unwinding device includes an unwinding bracket, on which an unwinding roller and a tension roller assembly are provided, on which a negative electrode sheet is wound, the unwinding roller unwinds the negative electrode sheet and bypasses the tension roller assembly, and the negative electrode sheet enters the lithium coating device and bypasses the feed conductive roller.

[0016] Preferably, the tension roller assembly includes a fixed roller fixedly arranged on the unwinding bracket, and at least one adjusting roller slidably arranged on the unwinding bracket, which determines the position of the adjusting roller, fixes and cooperates with the fixed roller to adjust the tension of the negative electrode sheet.

[0017] Preferably, a slide rail is vertically arranged on the unwinding bracket, the adjusting roller is slidably arranged on the slide rail, the adjusting roller is connected with a lifter, and the lifter is used to drive the adjusting roller to move along the slide rail.

[0018] As a preferred technical solution of the present invention, the lithium source includes a lithium block and / or a lithium plate.

[0019] Preferably, the feed conductive roller comprises an upper feed roller and a lower feed roller, the upper feed roller and the lower feed roller press the negative electrode sheet, and the lithium source is electrically connected to the upper feed roller.

[0020] Preferably, the upper feed roller and the lower feed roller are both made of conductive rubber.

[0021] Preferably, the guide rollers are staggered in the shell, and the negative electrode sheets are arranged in a serpentine shape around the guide rollers in the shell.

[0022] Preferably, the guide rollers are arranged in a staggered manner on both sides of the lithium source, and the negative electrode plates are arranged in a serpentine shape on both sides of the lithium source.

[0023] Preferably, the negative electrode sheet passes around the guide roller, and the negative electrode sheet moves in a serpentine shape along the vertical direction.

[0024] The present invention enables the negative electrode plate to be immersed in the electrolyte to the greatest extent by means of the serpentine movement of the negative electrode plate, thereby saving the floor space occupied by the device.

[0025] Preferably, a liquid level sensor is provided on the shell, and the liquid level sensor is used to detect the liquid level height of the electrolyte in the shell.

[0026] Preferably, the shell is externally connected to a liquid storage tank for storing electrolyte, and a solenoid valve is provided on the pipeline connecting the liquid storage tank and the shell.

[0027] As a preferred technical solution of the present invention, the drying device comprises a box body, and a heater is arranged in the box body.

[0028] Preferably, a temperature sensor is provided in the box.

[0029] Preferably, the box body is provided with an air inlet at the discharge end of the negative electrode sheet, and the box body is provided with an air outlet at the feed end of the negative electrode sheet.

[0030] Preferably, the air outlet is connected to an exhaust gas processor.

[0031] Preferably, the winding device comprises a winding roller.

[0032] Preferably, the winding device is also provided with a tension roller assembly.

[0033] As a preferred technical solution of the present invention, the system device also includes a power device, and the power device includes a driving member independently connected to the unwinding roller and the winding roller, and the driving member drives the unwinding roller and the winding roller to rotate respectively.

[0034] Preferably, the power device further comprises a solution pump located on a pipeline connecting the liquid storage tank and the shell.

[0035] Preferably, the power device also includes a fan connected to the air inlet.

[0036] As a preferred technical solution of the present invention, the system device also includes a control device, which is independently and electrically connected to the current regulator, ultrasonic generator, lifter and driving member, and the control device controls the regulating current of the current regulator, the power of the ultrasonic generator, the movement of the lifter and the rotation speed of the driving member respectively.

[0037] Preferably, the control device is also independently electrically connected to the temperature sensor, heater and fan, and the control device receives the temperature signal of the temperature sensor and feedback controls the heating temperature of the heater and the air volume of the fan.

[0038] Preferably, the control device is also independently electrically connected to the liquid level sensor, the solenoid valve and the solution pump, and the control device receives the liquid level signal from the liquid level sensor and feedback controls the opening of the solenoid valve and the flow rate of the solution pump.

[0039] In a second aspect, the present invention provides a method for coating a negative electrode sheet with lithium using the negative electrode sheet coating system device described in the first aspect, the method comprising:

[0040] The negative electrode sheet passes around the feed conductive roller and the guide roller in turn and is immersed in the electrolyte, and is electrically connected to the lithium source through the feed conductive roller to form a primary battery. The current regulator adjusts the current between the negative electrode sheet and the lithium source for lithium coating. The negative electrode sheet after lithium coating enters the cleaning device for ultrasonic cleaning to obtain a lithium-coated negative electrode sheet.

[0041] As a preferred technical solution of the present invention, the method specifically comprises the following steps:

[0042] (I) The negative electrode sheet passes around the adjusting roller and the fixed roller, and the lifting device adjusts the position of the adjusting roller to tighten the negative electrode sheet. The negative electrode sheet is pressed by the feeding upper roller and the feeding lower roller, and passes around the guide roller to be immersed in the electrolyte. The negative electrode sheet immersed in the electrolyte forms a primary battery with the lithium source. The current regulator adjusts the current between the negative electrode sheet and the lithium source to coat the lithium. The lithium-coated negative electrode sheet is ultrasonically cleaned, enters the drying device after cleaning, and is wound up by the winding roller. The waste gas generated by drying enters the waste gas processor;

[0043] (II) When the liquid level sensor detects that the liquid level is lower than the lower limit value, the control device controls the solution pump and the solenoid valve to open, and the electrolyte is injected into the shell from the liquid storage tank, so that the liquid level of the electrolyte in the shell is lower than the upper limit value.

[0044] As a preferred technical solution of the present invention, in step (I), the control device adjusts the rotation speed of the unwinding roller and the rotation speed of the winding roller, and the lithium coating process is carried out intermittently or continuously.

[0045] Preferably, during the lithium coating process, the adjustment step includes at least one current adjustment.

[0046] Preferably, the step of adjusting includes at least two current adjustments.

[0047] Preferably, the current of the current regulation increases sequentially each time.

[0048] Preferably, the time of each current regulation increases successively.

[0049] Preferably, the current adjustment range is 0.005~1C, for example, the current is 0.005C, 0.05C, 0.10C, 0.15C, 0.20C, 0.25C, 0.30C, 0.35C, 0.40C, 0.45C, 0.50C, 0.55C, 0.60C, 0.65C, 0.70C, 0.75C, 0.80C, 0.85C, 0.90C, 0.95C or 1.00C.

[0050] The present invention controls the current intensity and time in the current regulation to precisely control the amount of lithium coating and ensure the uniformity of lithium coating. If the current is adjusted to less than 0.005C, a long time of lithium coating is required, which affects the efficiency of electrode preparation; if the current is adjusted to greater than 1C, the current is too large during the lithium coating process, resulting in a dense SEI film and increasing the electrode resistance, which affects the battery rate and has a poor lithium coating effect.

[0051] Preferably, the current regulation time is 0 to 3 h, excluding 0, for example, the time is 0.01 h, 0.1 h, 0.2 h, 0.5 h, 1.0 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h, 2.0 h, 2.2 h, 2.4 h, 2.6 h, 2.8 h or 3.0 h.

[0052] Preferably, the lithium coating process is carried out under a protective atmosphere.

[0053] Preferably, the protective atmosphere comprises nitrogen and / or argon.

[0054] Preferably, the frequency of the ultrasound is 10 to 50 kHz, for example, a frequency of 10 kHz, 15 kHz, 20 kHz, 25 kHz, 30 kHz, 35 kHz, 40 kHz, 45 kHz or 50 kHz.

[0055] The present invention controls the frequency of ultrasound to be 10 to 50 kHz, and further cleans the lithium-coated negative electrode plate through ultrasound, which can not only clean the residual electrolyte 208 on the negative electrode plate, but also strengthen the bonding effect between the lithium coating and the negative electrode plate. If the frequency of ultrasound is lower than 10 kHz, the negative electrode plate is not completely cleaned, and the first efficiency of the prepared battery is low and the cycle performance is degraded; if the frequency of ultrasound is higher than 50 kHz, for the negative electrode plate with low stripping force, it is easy to cause the problem of active material falling off, affecting the lithium coating effect.

[0056] Preferably, the power of the ultrasound is 10-100W, for example, the power is 10W, 20W, 30W, 40W, 50W, 60W, 70W, 80W, 90W or 100W.

[0057] Preferably, in step (II), the lower limit of the liquid level is located at the horizontal plane where the lowest point of the cross-sectional circle of the guide rail at the top layer is located.

[0058] Preferably, the upper limit of the liquid level is located at the horizontal plane where the highest point of the cross-sectional circle of the guide rail at the top layer is located.

[0059] As a preferred technical solution of the present invention, the method specifically comprises the following steps:

[0060] (I) The negative electrode sheet passes around the adjusting roller and the fixed roller, and the lifting device adjusts the position of the adjusting roller to tighten the negative electrode sheet. The negative electrode sheet is pressed by the feeding upper roller and the feeding lower roller, and passes around the guide roller to be immersed in the electrolyte. The negative electrode sheet immersed in the electrolyte forms a primary battery with the lithium source. Under the protective atmosphere, the current regulator adjusts the current between the negative electrode sheet and the lithium source at least twice to coat lithium. The current adjustment range is 0.005-1C, and the time is 0-3h. The current and time of each current adjustment are increased in turn. The control device adjusts the speed of the unwinding roller and the speed of the winding roller. The lithium coating process is intermittent or continuous. The lithium-coated negative electrode sheet is ultrasonically cleaned. The frequency of the ultrasound is 10-50kHz and the power is 10-100W. After cleaning, it enters the drying device and is wound by the winding roller. The waste gas generated by drying enters the waste gas processor;

[0061] (II) When the liquid level sensor detects that the liquid level is lower than the horizontal plane where the lowest point of the cross-sectional circle of the guide rail on the top layer is located, the control device controls the solution pump and the solenoid valve to open, and the electrolyte is injected into the shell from the liquid storage tank, so that the liquid level of the electrolyte in the shell is lower than the horizontal plane where the highest point of the cross-sectional circle of the guide rail on the top layer is located.

[0062] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0063] Compared with the prior art, the present invention has the following beneficial effects:

[0064] In the present invention, the negative electrode plate is connected to a lithium source to form a primary battery, and the current between the negative electrode plate and the lithium source is adjusted by a current regulator. No external power source is required to electrochemically coat the plate with lithium, and the lithium coating on both sides of the negative electrode plate is uniform and stable. Furthermore, by adjusting the current size and time, the amount of lithium coating can be accurately controlled. In addition, during the electrochemical lithium coating process, a side reaction simultaneously occurs at the interface where the negative electrode plate contacts the electrolyte to form an SEI film, which can reduce the consumption of active lithium in the electrolyte and the positive electrode material during battery formation, and effectively improve the initial coulombic efficiency and later cycle performance of the battery. The lithium-coated negative electrode plate of the present invention is ultrasonically cleaned to make the negative electrode plate uniformly and stably coated with lithium, and has the characteristics of simple structure, adjustable lithium coating thickness, and easy industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 It is a structural schematic diagram of a negative electrode plate lithium coating system device provided in a specific embodiment of the present invention.

[0066] Among them, 100-unwinding device; 101-unwinding roller; 102-adjusting roller; 103-fixed roller; 200-lithium coating device; 201-feeding conductive roller; 202-conducting wire; 203-current regulator; 204-lithium source; 205-liquid level sensor; 206-guide roller; 207-housing; 208-electrolyte; 209-solenoid valve; 210-liquid storage tank; 211-solution pump; 300-cleaning device; 400-drying device; 401-air inlet; 402-box; 403-air outlet; 500-exhaust gas processor; 600-winding device; 601-winding roller. DETAILED DESCRIPTION

[0067] It should be understood that, in the description of the present invention, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0068] It should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0069] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0070] In a specific embodiment, the present invention provides a negative electrode plate lithium coating system device, such as Figure 1 As shown, the system device includes a lithium coating device 200 and a cleaning device 300, the lithium coating device 200 includes a shell 207 injected with an electrolyte 208, at least one guide roller 206 is arranged in the shell 207, and a lithium source 204 immersed in the electrolyte 208 is also arranged in the shell 207, and a feeding conductive roller 201 is arranged at the feeding end of the shell 207, the feeding conductive roller 201 is electrically connected to the lithium source 204, and a current regulator 203 is arranged on the line where the feeding conductive roller 201 and the lithium source 204 are electrically connected, the negative electrode plate bypasses the feeding conductive roller 201 and the guide roller 206, and is immersed in the electrolyte 208, and the negative electrode plate is electrically connected to the lithium source 204 through the feeding conductive roller 201 for lithium coating; an ultrasonic generator is arranged in the cleaning device 300, and the negative electrode plate after lithium coating enters the cleaning device 300 for cleaning, and optionally, the electrical connection is connected by a wire 202.

[0071] In the present invention, the negative electrode plate is connected to the lithium source 204 to form a primary battery, and the current between the negative electrode plate and the lithium source 204 is adjusted by the current regulator 203. No external power supply is required to electrochemically coat the plate with lithium, and the lithium coating on both sides of the negative electrode plate is uniform and stable. Furthermore, by adjusting the current size and time, the amount of lithium coating can be accurately controlled. In addition, in the process of electrochemical lithium coating, side reactions occur simultaneously on the interface where the negative electrode plate contacts the electrolyte 208 to form an SEI film. When the battery is formed, the consumption of active lithium in the electrolyte 208 and the positive electrode material can be reduced, and the initial coulomb efficiency and later cycle performance of the battery can be effectively improved. After ultrasonic cleaning, the lithium-coated negative electrode plate of the present invention is uniformly and stably coated with lithium, and has the characteristics of simple structure, adjustable lithium coating thickness and easy industrialization.

[0072] Furthermore, the system device further comprises an unwinding device 100, a drying device 400 and a winding device 600. Along the processing direction of the negative electrode sheet, the system device comprises an unwinding device 100, a lithium coating device 200, a cleaning device 300, a drying device 400 and a winding device 600 which are sequentially arranged. Furthermore, a cleaning agent is injected into the cleaning device 300.

[0073] Furthermore, the unwinding device 100 includes an unwinding bracket, on which an unwinding roller 101 and a tension roller assembly are provided, and a negative electrode sheet is wound on the unwinding roller 101. The unwinding roller 101 unwinds the negative electrode sheet and bypasses the tension roller assembly. The negative electrode sheet enters the lithium coating device 200 and bypasses the feed conductive roller 201.

[0074] Furthermore, the tension roller assembly includes a fixed roller 103 fixedly arranged on the unwinding bracket, and at least one adjusting roller 102 slidably arranged on the unwinding bracket, and the adjusting roller 102 is positioned and fixed and cooperated with the fixed roller 103 to adjust the tension of the negative electrode sheet.

[0075] Furthermore, a slide rail is vertically arranged on the unwinding bracket, and the adjusting roller 102 is slidably arranged on the slide rail. The adjusting roller 102 is connected to a lifter, and the lifter is used to drive the adjusting roller 102 to move along the slide rail.

[0076] Further, the lithium source 204 includes a lithium block and / or a lithium plate. The feed conductive roller 201 includes an upper feed roller and a lower feed roller, the upper feed roller and the lower feed roller press the negative electrode sheet, and the lithium source 204 is electrically connected to the upper feed roller. Further, the material of the upper feed roller and the lower feed roller is conductive rubber.

[0077] Furthermore, the guide rollers 206 are staggered in the housing 207, and the negative electrode sheets are arranged in a serpentine shape around the guide rollers 206 in the housing 207. Furthermore, the guide rollers 206 are staggered on both sides of the lithium source 204, and the negative electrode sheets are arranged in a serpentine shape on both sides of the lithium source 204. The negative electrode sheets bypass the guide rollers 206, and the negative electrode sheets move in a serpentine shape in the vertical direction. The present invention allows the negative electrode sheets to be immersed in the electrolyte 208 to the greatest extent through the serpentine movement of the negative electrode sheets, thereby saving the floor space of the device.

[0078] Furthermore, a liquid level sensor 205 is provided on the housing 207, and the liquid level sensor 205 is used to detect the liquid level of the electrolyte 208 in the housing 207. The housing 207 is externally connected to a liquid storage tank 210 for storing the electrolyte 208, and a solenoid valve 209 is provided on the pipeline connecting the liquid storage tank 210 and the housing 207.

[0079] Furthermore, the drying device 400 includes a box 402, in which a heater is provided. A temperature sensor is provided in the box 402. The box 402 is provided with an air inlet 401 at the discharge end of the negative electrode sheet, and the box 402 is provided with an air outlet 403 at the feed end of the negative electrode sheet. The air outlet 403 is connected to the exhaust gas processor 500.

[0080] Further, the winding device 600 comprises a winding roller 601. Further, the winding device 600 is also provided with a tension roller assembly.

[0081] Furthermore, the system device further comprises a power device, which comprises a driving member independently connected to the unwinding roller 101 and the winding roller 601, and the driving member drives the unwinding roller 101 and the winding roller 601 to rotate. Furthermore, the power device further comprises a solution pump 211 located on the pipeline connecting the liquid storage tank 210 and the housing 207, and a fan connected to the air inlet 401.

[0082] Furthermore, the system device also includes a control device, which is independently electrically connected to the current regulator 203, the ultrasonic generator, the lifter and the driving member, and the control device controls the regulating current of the current regulator 203, the power of the ultrasonic generator, the movement of the lifter and the rotation speed of the driving member.

[0083] Furthermore, the control device is also independently electrically connected to the temperature sensor, the heater and the fan, and receives the temperature signal from the temperature sensor and feedback-controls the heating temperature of the heater and the air volume of the fan.

[0084] Furthermore, the control device is also independently electrically connected to the liquid level sensor 205 , the solenoid valve 209 and the solution pump 211 , and receives the liquid level signal from the liquid level sensor 205 , and feedback controls the opening of the solenoid valve 209 and the flow rate of the solution pump 211 .

[0085] In another specific embodiment, the present invention provides a method for coating a negative electrode sheet with lithium using the above-mentioned negative electrode sheet lithium coating system, the method comprising:

[0086] (I) The negative electrode sheet passes through the adjusting roller 102 and the fixed roller 103, and the lifting device adjusts the position of the adjusting roller 102 to tighten the negative electrode sheet. The negative electrode sheet is pressed by the feeding upper roller and the feeding lower roller, and passes through the guide roller 206 and is immersed in the electrolyte 208. The negative electrode sheet immersed in the electrolyte 208 forms a primary battery with the lithium source 204. Under the protective atmosphere, the current regulator 203 adjusts the current between the negative electrode sheet and the lithium source 204 at least twice to coat lithium. The current adjustment range is 0.005-1C, and the time is 0-3h. The current and time of each current adjustment are increased in turn. The control device adjusts the speed of the unwinding roller 101 and the speed of the winding roller 601. The lithium coating process is intermittent or continuous. The lithium-coated negative electrode sheet is ultrasonically cleaned. The frequency of the ultrasound is 10-50kHz and the power is 10-100W. After cleaning, it enters the drying device 400 and is wound by the winding roller 601. The waste gas generated by drying enters the waste gas processor 500;

[0087] (II) When the liquid level sensor detects that the liquid level is lower than the horizontal plane where the lowest point of the cross-sectional circle of the guide rail on the top layer is located, the control device controls the solution pump 211 and the solenoid valve 209 to open, and the electrolyte 208 is injected into the shell 207 from the liquid storage tank 210, so that the liquid level of the electrolyte 208 in the shell 207 is lower than the horizontal plane where the highest point of the cross-sectional circle of the guide rail on the top layer is located.

[0088] In the following embodiments and comparative examples, the area of ​​the negative electrode plate immersed in the electrolyte 208 is 600 mm*50 mm, and the graphite capacity is 343 mAh / g.

[0089] Example 1

[0090] The present embodiment provides a negative electrode plate lithium coating system device, based on a system device described in a specific embodiment, wherein six guide rollers 206 are arranged in the shell 207, and the tension roller assembly includes an adjustment roller 102 slidably arranged on the unwinding bracket.

[0091] This embodiment also provides a method for coating a negative electrode sheet with lithium using the above-mentioned negative electrode sheet lithium coating system device, and the method specifically includes the following steps:

[0092] (I) The negative electrode sheet passes through the adjusting roller 102 and the fixed roller 103, and the lifting device adjusts the position of the adjusting roller 102 to tighten the negative electrode sheet. The negative electrode sheet is pressed by the feeding upper roller and the feeding lower roller, and passes through the guide roller 206 and is immersed in the electrolyte 208. The negative electrode sheet immersed in the electrolyte 208 forms a primary battery with the lithium source 204. In the nitrogen atmosphere, the current regulator 203 adjusts the current between the negative electrode sheet and the lithium source 204 three times to coat lithium. The first current is adjusted to 0.05C and the time is 72s, the second current is adjusted to 0.1C, the time is 324s, the third current is adjusted to 0.5C, the time is 576s, the control device adjusts the speed of the unwinding roller 101 and the speed of the winding roller 601, the lithium coating process is intermittent or continuous, the lithium-coated negative electrode is ultrasonically cleaned, the frequency of the ultrasound is 30kHz, the power is 55W, after cleaning, it enters the drying device 400 and is wound by the winding roller 601, and the waste gas generated by drying enters the waste gas processor 500;

[0093] (II) When the liquid level sensor detects that the liquid level is lower than the horizontal plane where the lowest point of the cross-sectional circle of the guide rail on the top layer is located, the control device controls the solution pump 211 and the solenoid valve 209 to open, and the electrolyte 208 is injected into the shell 207 from the liquid storage tank 210, so that the liquid level of the electrolyte 208 in the shell 207 is lower than the horizontal plane where the highest point of the cross-sectional circle of the guide rail on the top layer is located.

[0094] Example 2

[0095] The present embodiment provides a negative electrode plate lithium coating system device, based on a system device described in a specific embodiment, wherein eight guide rollers 206 are arranged in the shell 207, and the tension roller assembly includes an adjustment roller 102 slidably arranged on the unwinding bracket.

[0096] This embodiment also provides a method for coating a negative electrode sheet with lithium using the above-mentioned negative electrode sheet lithium coating system device, and the method specifically includes the following steps:

[0097] (I) The negative electrode sheet passes through the adjusting roller 102 and the fixed roller 103, and the lifting device adjusts the position of the adjusting roller 102 to tighten the negative electrode sheet. The negative electrode sheet is pressed by the feeding upper roller and the feeding lower roller, and passes through the guide roller 206 and is immersed in the electrolyte 208. The negative electrode sheet immersed in the electrolyte 208 forms a primary battery with the lithium source 204. Under the argon atmosphere, the current regulator 203 adjusts the current between the negative electrode sheet and the lithium source 204 twice to coat lithium. The first current is adjusted to 0.1C for 360s, and the second current is adjusted to 0.5C for 864s. The control device adjusts the speed of the unwinding roller 101 and the speed of the winding roller 601. The lithium coating process is performed intermittently or continuously. The lithium-coated negative electrode sheet is ultrasonically cleaned with an ultrasonic frequency of 10kHz and a power of 10W. After cleaning, it enters the drying device 400 and is wound by the winding roller 601. The waste gas generated by drying enters the waste gas processor 500;

[0098] (II) When the liquid level sensor detects that the liquid level is lower than the horizontal plane where the lowest point of the cross-sectional circle of the guide rail on the top layer is located, the control device controls the solution pump 211 and the solenoid valve 209 to open, and the electrolyte 208 is injected into the shell 207 from the liquid storage tank 210, so that the liquid level of the electrolyte 208 in the shell 207 is lower than the horizontal plane where the highest point of the cross-sectional circle of the guide rail on the top layer is located.

[0099] Example 3

[0100] The present embodiment provides a negative electrode plate lithium coating system device, based on a system device described in a specific embodiment, wherein ten guide rollers 206 are arranged in the shell 207, and the tension roller assembly includes two adjustment rollers 102 slidably arranged on the unwinding bracket.

[0101] This embodiment also provides a method for coating a negative electrode sheet with lithium using the above-mentioned negative electrode sheet lithium coating system device, and the method specifically includes the following steps:

[0102] (I) The negative electrode sheet passes through the adjusting roller 102 and the fixed roller 103, and the lifting device adjusts the position of the adjusting roller 102 to tighten the negative electrode sheet. The negative electrode sheet is pressed by the feeding upper roller and the feeding lower roller, and passes through the guide roller 206 and is immersed in the electrolyte 208. The negative electrode sheet immersed in the electrolyte 208 forms a primary battery with the lithium source 204. Under the nitrogen atmosphere, the current regulator 203 adjusts the current between the negative electrode sheet and the lithium source 204 twice to coat lithium. The first current is adjusted to 0.1C for 360s, and the second current is adjusted to 0.5C for 1152s. The control device adjusts the speed of the unwinding roller 101 and the speed of the winding roller 601. The lithium coating process is intermittent or continuous. The lithium-coated negative electrode sheet is ultrasonically cleaned with an ultrasonic frequency of 50kHz and a power of 100W. After cleaning, it enters the drying device 400 and is wound by the winding roller 601. The waste gas generated by drying enters the waste gas processor 500;

[0103] (II) When the liquid level sensor detects that the liquid level is lower than the horizontal plane where the lowest point of the cross-sectional circle of the guide rail on the top layer is located, the control device controls the solution pump 211 and the solenoid valve 209 to open, and the electrolyte 208 is injected into the shell 207 from the liquid storage tank 210, so that the liquid level of the electrolyte 208 in the shell 207 is lower than the horizontal plane where the highest point of the cross-sectional circle of the guide rail on the top layer is located.

[0104] Example 4

[0105] The present embodiment provides a negative electrode plate lithium coating system device, based on a system device described in a specific embodiment, wherein twelve guide rollers 206 are arranged in the shell 207, and the tension roller assembly includes an adjustment roller 102 slidably arranged on the unwinding bracket.

[0106] This embodiment also provides a method for coating a negative electrode sheet with lithium using the above-mentioned negative electrode sheet lithium coating system device, and the method specifically includes the following steps:

[0107] (I) The negative electrode sheet passes through the adjusting roller 102 and the fixed roller 103, and the lifting device adjusts the position of the adjusting roller 102 to tighten the negative electrode sheet. The negative electrode sheet is pressed by the feeding upper roller and the feeding lower roller, and passes through the guide roller 206 and is immersed in the electrolyte 208. The negative electrode sheet immersed in the electrolyte 208 forms a primary battery with the lithium source 204. Under the argon atmosphere, the current regulator 203 adjusts the current between the negative electrode sheet and the lithium source 204 twice to coat lithium. The first current is adjusted to 0.1C for 360s, and the second current is adjusted to 0.5C for 1368s. The control device adjusts the speed of the unwinding roller 101 and the speed of the winding roller 601. The lithium coating process is intermittent or continuous. The lithium-coated negative electrode sheet is ultrasonically cleaned with an ultrasonic frequency of 20kHz and a power of 30W. After cleaning, it enters the drying device 400 and is wound by the winding roller 601. The waste gas generated by drying enters the waste gas processor 500;

[0108] (II) When the liquid level sensor detects that the liquid level is lower than the horizontal plane where the lowest point of the cross-sectional circle of the guide rail on the top layer is located, the control device controls the solution pump 211 and the solenoid valve 209 to open, and the electrolyte 208 is injected into the shell 207 from the liquid storage tank 210, so that the liquid level of the electrolyte 208 in the shell 207 is lower than the horizontal plane where the highest point of the cross-sectional circle of the guide rail on the top layer is located.

[0109] Example 5

[0110] The present embodiment provides a negative electrode plate lithium coating system device, based on a system device described in a specific embodiment, wherein fourteen guide rollers 206 are arranged in the shell 207, and the tension roller assembly includes two adjustment rollers 102 slidably arranged on the unwinding bracket.

[0111] This embodiment also provides a method for coating a negative electrode sheet with lithium using the above-mentioned negative electrode sheet lithium coating system device, and the method specifically includes the following steps:

[0112] (I) The negative electrode sheet passes through the adjusting roller 102 and the fixed roller 103. The lifting device adjusts the position of the adjusting roller 102 to tighten the negative electrode sheet. The negative electrode sheet is pressed by the feeding upper roller and the feeding lower roller, and passes through the guide roller 206 and is immersed in the electrolyte 208. The negative electrode sheet immersed in the electrolyte 208 forms a primary battery with the lithium source 204. Under the protective atmosphere, the current regulator 203 adjusts the current between the negative electrode sheet and the lithium source 204 twice to coat lithium. The first current is adjusted to 0.05C and the time is 72s, the second current is adjusted to 0.1C, the time is 324s, the third current is adjusted to 0.5C, the time is 360s, the control device adjusts the speed of the unwinding roller 101 and the speed of the winding roller 601, the lithium coating process is intermittent or continuous, the lithium-coated negative electrode is ultrasonically cleaned, the frequency of the ultrasound is 40kHz, the power is 70W, after cleaning, it enters the drying device 400 and is wound by the winding roller 601, and the waste gas generated by drying enters the waste gas processor 500;

[0113] (II) When the liquid level sensor detects that the liquid level is lower than the horizontal plane where the lowest point of the cross-sectional circle of the guide rail on the top layer is located, the control device controls the solution pump 211 and the solenoid valve 209 to open, and the electrolyte 208 is injected into the shell 207 from the liquid storage tank 210, so that the liquid level of the electrolyte 208 in the shell 207 is lower than the horizontal plane where the highest point of the cross-sectional circle of the guide rail on the top layer is located.

[0114] Example 6

[0115] This embodiment provides a method for coating a negative electrode plate with lithium using the negative electrode plate lithium coating system device described in Example 1. The difference from Example 1 is that the first current is adjusted to 0.003C, and the remaining parameters and steps are exactly the same as those in Example 1.

[0116] Example 7

[0117] This embodiment provides a method for coating a negative electrode plate with lithium using the negative electrode plate lithium coating system device described in Example 1. The difference from Example 1 is that the third current is adjusted to 1.2C, and the other parameters and steps are exactly the same as those in Example 1.

[0118] Example 8

[0119] This embodiment provides a method for coating a negative electrode plate with lithium using the negative electrode plate lithium coating system device described in Example 1. The difference from Example 1 is that the frequency of the ultrasound is 5 kHz, and the other parameters and steps are exactly the same as those in Example 1.

[0120] Example 9

[0121] This embodiment provides a method for coating a negative electrode plate with lithium using the negative electrode plate lithium coating system device described in Example 1. The difference from Example 1 is that the frequency of the ultrasound is 60 kHz, and the other parameters and steps are exactly the same as those in Example 1.

[0122] Comparative Example 1

[0123] This comparative example provides a negative electrode plate, which, compared with Example 1, is not coated with lithium.

[0124] Comparative Example 2

[0125] This comparative example provides a method for coating a negative electrode with lithium. Compared with Example 1, the difference is that the coating method is conventional rolling lithium sheet coating, and the method is as follows:

[0126] The lithium sheet is pressed onto the surface of the negative electrode sheet by rolling to obtain a lithium-coated negative electrode sheet.

[0127] The lithium-coated negative electrode sheets in the above embodiments and comparative examples are assembled into a battery. The battery assembly method includes: welding the positive and negative electrode tabs corresponding to the exposed foils of the positive electrode sheet and the negative electrode sheet, aligning the diaphragm, the negative electrode sheet, the diaphragm, and the positive electrode sheet from bottom to top, wherein the diaphragm exceeds the negative electrode sheet, the negative electrode sheet exceeds the positive electrode sheet, the wound diaphragm exceeds the negative electrode sheet by 0.5 to 1.5 turns, and the negative electrode sheet exceeds the positive electrode sheet by 1.5 to 2.0 turns. Then the above components are wound into a winding core of fixed size, the negative electrode coating area at the winding core completely covers the positive electrode coating area, and the positive electrode tab of the wound winding core is welded to the top cover assembly; injecting liquid into the battery, placing the winding core with the welded top cover assembly into the steel shell, welding the negative electrode tab to the steel shell, and then injecting the electrolyte 208 into the steel shell; battery packaging, packaging the top cover assembly and the steel shell, and after a certain period of standing after packaging, the electrolyte 208 completely infiltrates the winding core.

[0128] The formation parameters of the embodiment and the comparative example are shown in Table 1. The formed battery was divided at room temperature, first allowed to stand for 30 minutes, then charged to 3.65V at a constant current of 0.5C, allowed to stand for 5 minutes, then charged at a constant voltage of 3.65V until the current dropped to 0.05C, allowed to stand for 5 minutes, and then discharged to 2.5V at a constant current of 0.5C.

[0129] After the batteries prepared in the above embodiments and comparative examples were divided into different capacities, the initial coulombic efficiency and the capacity retention rate after 1000 cycles of 1C charge / 1C discharge at 45°C were measured. The test results are shown in Table 2.

[0130] Table 1

[0131]

[0132]

[0133] Table 2

[0134]

[0135]

[0136] It can be seen from the above table:

[0137] (1) Compared with Examples 6 and 7, Example 1 has better initial coulombic efficiency and capacity retention than Examples 6 and 7. It can be seen that the present invention controls the current intensity and time in current regulation to accurately control the amount of lithium coating and ensure the uniformity of lithium coating. If the current is adjusted to less than 0.005C, a long time of lithium coating is required, which affects the efficiency of electrode preparation. If the current is adjusted to greater than 1C, the current is too large during the lithium coating process, and further an internal short circuit problem occurs, resulting in poor lithium coating effect.

[0138] (2) Compared with Examples 8 and 9, Example 1 has better initial coulombic efficiency and capacity retention than Examples 8 and 9. It can be seen that the present invention controls the frequency of ultrasound to 10 to 50 kHz, and further cleans the lithium-coated negative electrode plate by ultrasound, which can not only clean the residual electrolyte 208 on the negative electrode plate, but also strengthen the bonding effect between the lithium coating and the negative electrode plate. If the frequency of ultrasound is lower than 10 kHz, the negative electrode plate is not completely cleaned, and the first efficiency of the prepared battery is low and the cycle performance is degraded; if the frequency of ultrasound is higher than 50 kHz, for the negative electrode plate with small stripping force, it is easy to cause the problem of active material falling off, affecting the lithium coating effect.

[0139] (3) Compared with Comparative Examples 1 and 2, Example 1 has better initial coulombic efficiency and capacity retention rate than Comparative Examples 1 and 2. It can be seen that in the present invention, the negative electrode plate is connected to the lithium source 204 to form a primary battery, and the current between the negative electrode plate and the lithium source 204 is adjusted by the current regulator 203. No external power supply is required to electrochemically coat the plate with lithium, and the lithium coating on both sides of the negative electrode plate is uniform and stable. Furthermore, by adjusting the current size and time, the amount of lithium coating can be accurately controlled. In addition, during the electrochemical lithium coating process, side reactions occur simultaneously at the interface where the negative electrode plate contacts the electrolyte 208 to form an SEI film. When the battery is formed, the consumption of active lithium in the electrolyte 208 and the positive electrode material can be reduced, effectively improving the initial coulombic efficiency and later cycle performance of the battery. The lithium-coated negative electrode plate of the present invention is successively subjected to ultrasonic cleaning and drying to make the negative electrode plate uniformly and stably coated with lithium. It has the characteristics of simple structure, adjustable lithium coating thickness and easy industrialization.

[0140] The applicant declares that the above is only a specific implementation mode 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 thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for coating a negative electrode sheet with lithium using a negative electrode sheet coating system, characterized in that: The method includes: The negative electrode sheet passes through the feed conductive roller and the guide roller in turn and is immersed in the electrolyte, and is electrically connected to the lithium source through the feed conductive roller to form a primary battery. The current regulator adjusts the current between the negative electrode sheet and the lithium source to coat lithium. The negative electrode sheet after lithium coating enters the cleaning device for ultrasonic cleaning to obtain a negative electrode sheet coated with lithium; The amount of lithium coating is 9wt%; The current regulation range of the current regulator is 0.005~1C; The frequency of the ultrasonic cleaning is 30kHz; The system device comprises a lithium coating device and a cleaning device, wherein the lithium coating device comprises a shell injected with an electrolyte, wherein at least one guide roller is arranged in the shell, wherein a lithium source immersed in the electrolyte is also arranged in the shell, wherein the feed end of the shell is provided with the feed conductive roller, wherein the feed conductive roller is electrically connected to the lithium source, and wherein the current regulator is arranged on the line where the feed conductive roller is electrically connected to the lithium source; The cleaning device is provided with an ultrasonic generator, and the negative electrode sheet coated with lithium enters the cleaning device for cleaning.

2. The method according to claim 1, characterized in that: The system device also includes a unwinding device, a drying device and a winding device. Along the processing direction of the negative electrode sheet, the system device includes an unwinding device, a lithium coating device, a cleaning device, a drying device and a winding device which are arranged in sequence.

3. The method according to claim 2, characterized in that The cleaning device is filled with cleaning agent.

4. The method according to claim 2, characterized in that: The unwinding device includes an unwinding bracket, on which an unwinding roller and a tension roller assembly are arranged, on which a negative electrode sheet is wound, the unwinding roller unwinds the negative electrode sheet and bypasses the tension roller assembly, and the negative electrode sheet enters the lithium coating device and bypasses the feed conductive roller.

5. The method according to claim 4, characterized in that The tension roller assembly includes a fixed roller fixedly arranged on the unwinding bracket, and at least one adjusting roller slidably arranged on the unwinding bracket, which determines the position of the adjusting roller, fixes and cooperates with the fixed roller to adjust the tension of the negative electrode sheet.

6. The method according to claim 4, characterized in that A slide rail is vertically arranged on the unwinding bracket, the adjusting roller is slidably arranged on the slide rail, and the adjusting roller is connected with a lifter, and the lifter is used to drive the adjusting roller to move along the slide rail.

7. The method according to claim 1, characterized in that The lithium source includes lithium blocks and / or lithium plates.

8. The method according to claim 1, characterized in that The feed conductive roller comprises an upper feed roller and a lower feed roller, the upper feed roller and the lower feed roller press the negative electrode sheet, and the lithium source is electrically connected to the upper feed roller.

9. The method according to claim 8, characterized in that The material of the upper feed roller and the lower feed roller is conductive rubber.

10. The method according to claim 1, characterized in that The guide rollers are arranged in a staggered manner in the shell, and the negative electrode sheets are arranged in a serpentine shape around the guide rollers in the shell.

11. The method according to claim 1, characterized in that: The guide rollers are arranged in a staggered manner on both sides of the lithium source, and the negative electrode plates are arranged in a serpentine manner on both sides of the lithium source.

12. The method according to claim 1, characterized in that The negative electrode sheet passes around the guide roller, and the negative electrode sheet moves in a serpentine shape along the vertical direction.

13. The method according to claim 2, characterized in that The shell is provided with a liquid level sensor, and the liquid level sensor is used to detect the liquid level height of the electrolyte in the shell.

14. The method according to claim 13, characterized in that The shell is externally connected with a liquid storage tank for storing electrolyte, and a solenoid valve is arranged on the pipeline connecting the liquid storage tank and the shell.

15. The method according to claim 14, characterized in that The drying device comprises a box body, in which a heater is arranged.

16. The method according to claim 15, characterized in that A temperature sensor is arranged in the box.

17. The method according to claim 16, characterized in that The box body is provided with an air inlet at the discharge end of the negative electrode sheet, and the box body is provided with an air outlet at the feed end of the negative electrode sheet.

18. The method according to claim 17, characterized in that The air outlet is connected with an exhaust gas processor.

19. The method according to claim 18, characterized in that The winding device comprises a winding roller.

20. The method according to claim 18, characterized in that The winding device is also provided with a tension roller assembly.

21. The method according to claim 20, characterized in that The system device also includes a power device, which includes a driving member independently connected to the unwinding roller and the winding roller, and the driving member drives the unwinding roller and the winding roller to rotate respectively.

22. The method according to claim 21, characterized in that The power device also includes a solution pump located on a pipeline connecting the liquid storage tank and the shell.

23. The method according to claim 22, characterized in that The power device also includes a fan connected to the air inlet.

24. The method according to claim 23, characterized in that The system device also includes a control device, which is independently and electrically connected to the current regulator, ultrasonic generator, lifter and driving member, and the control device controls the regulating current of the current regulator, the power of the ultrasonic generator, the movement of the lifter and the rotation speed of the driving member.

25. The method according to claim 24, characterized in that The control device is also independently and electrically connected to the temperature sensor, heater and fan, respectively. The control device receives the temperature signal from the temperature sensor and feedback-controls the heating temperature of the heater and the air volume of the fan.

26. The method according to claim 24, characterized in that The control device is also independently and electrically connected to the liquid level sensor, the solenoid valve and the solution pump. The control device receives the liquid level signal from the liquid level sensor and feedback controls the opening of the solenoid valve and the flow rate of the solution pump.

27. The method according to claim 26, characterized in that The method specifically comprises the following steps: (I) The negative electrode sheet passes around the adjusting roller and the fixed roller, and the lifting device adjusts the position of the adjusting roller to tighten the negative electrode sheet. The negative electrode sheet is pressed by the feeding upper roller and the feeding lower roller, and passes around the guide roller to be immersed in the electrolyte. The negative electrode sheet immersed in the electrolyte forms a primary battery with the lithium source. The current regulator adjusts the current between the negative electrode sheet and the lithium source to coat the lithium. The lithium-coated negative electrode sheet is ultrasonically cleaned, enters the drying device after cleaning, and is wound up by the winding roller. The waste gas generated by drying enters the waste gas processor; (II) When the liquid level sensor detects that the liquid level is lower than the lower limit value, the control device controls the solution pump and the solenoid valve to open, and the electrolyte is injected into the shell from the liquid storage tank, so that the liquid level of the electrolyte in the shell is lower than the upper limit value.

28. The method according to claim 27, characterized in that In step (I), the control device adjusts the rotation speed of the unwinding roller and the rotation speed of the winding roller, and the lithium coating process is carried out intermittently or continuously.

29. The method according to claim 28, characterized in that In the lithium coating process, the regulating step includes at least one current regulation.

30. The method according to claim 29, characterized in that The step of adjusting includes at least two current adjustments.

31. The method according to claim 30, characterized in that The current of the current regulation increases successively each time.

32. The method according to claim 30, characterized in that The time of each current regulation increases successively.

33. The method according to claim 30, characterized in that The current adjustment time is 0 to 3 hours, but excluding 0.

34. The method according to claim 27, characterized in that The lithium coating process is carried out under a protective atmosphere.

35. The method according to claim 34, characterized in that The protective atmosphere includes nitrogen and / or argon.

36. The method according to claim 27, characterized in that The power of the ultrasound is 10-100W.

37. The method according to claim 27, characterized in that In step (II), the lower limit of the liquid level is located at the horizontal plane where the lowest point of the cross-sectional circle of the guide rail at the top layer is located.

38. The method according to claim 27, characterized in that The upper limit of the liquid level is located at the horizontal plane where the highest point of the cross-sectional circle of the guide rail at the top layer is located.

39. The method according to claim 38, characterized in that The method specifically comprises the following steps: (I) The negative electrode sheet passes through the adjusting roller and the fixed roller, and the lifting device adjusts the position of the adjusting roller to tighten the negative electrode sheet. The negative electrode sheet is pressed by the feeding upper roller and the feeding lower roller, and passes through the guide roller to be immersed in the electrolyte. The negative electrode sheet immersed in the electrolyte forms a primary battery with the lithium source. Under the protective atmosphere, the current regulator adjusts the current between the negative electrode sheet and the lithium source at least twice to coat lithium. The current adjustment range is 0.005-1C, and the time is 0-3h. The current and time of each current adjustment are increased in turn. The control device adjusts the speed of the unwinding roller and the speed of the winding roller. The lithium coating process is intermittent or continuous. The lithium-coated negative electrode sheet is ultrasonically cleaned. The frequency of the ultrasound is 10-50kHz and the power is 10-100W. After cleaning, it enters the drying device and is wound up by the winding roller. The waste gas generated by drying enters the waste gas processor; (II) When the liquid level sensor detects that the liquid level is lower than the horizontal plane where the lowest point of the cross-sectional circle of the guide rail on the top layer is located, the control device controls the solution pump and the solenoid valve to open, and the electrolyte is injected into the shell from the liquid storage tank, so that the liquid level of the electrolyte in the shell is lower than the horizontal plane where the highest point of the cross-sectional circle of the guide rail on the top layer is located.

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