Pre-lithiation equipment and pre-lithiation method

Abstract

The invention discloses pre-lithiation equipment and a pre-lithiation method, and belongs to the technical field of battery material processing. The pre-lithiation equipment comprises a fixed roller, a first movable roller, a second movable roller, an initial pole piece unwinding device, a first base film unwinding device, a first lithium supplementing material unwinding device, a pre-lithiation pole piece winding device and a first base film winding device, the first movable roller and the second movable roller are respectively arranged above and below the fixed roller at intervals; a first gap is formed between the first movable roller and the fixed roller, so that the first lithium supplementing material forms a first lithium film and is transferred to the surface of the fixed roller; and a second gap is formed between the second movable roller and the fixed roller, so that the initial pole piece is combined with the first lithium film transferred to the surface of the fixed roller in a rolling manner, and a pre-lithiated pole piece of which the single surface is pre-lithiated is obtained. According to the scheme, the pole piece can be pre-lithiated while the lithium supplementing material is rolled, the transportation and storage risks of the lithium supplementing material are reduced, the production efficiency is high, and the cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of battery material processing, and in particular to a pre-lithiation device and a pre-lithiation method. Background Art

[0002] In order to improve the cycle life and cycle efficiency of batteries, major battery cell companies have proposed solutions on how to improve battery performance. Among them, since metallic lithium is currently the most promising battery material for improving energy density and cycle performance, downstream manufacturers hope to pre-lithiate the battery electrodes to compensate for the loss of active lithium caused by the formation of SEI film during the first cycle of the lithium battery, thereby improving the cycle life of the lithium battery and increasing the coulombic efficiency of the first cycle of the lithium battery.

[0003] Pre-lithiation is generally divided into positive electrode pre-lithiation and negative electrode pre-lithiation. Positive electrode pre-lithiation requires the addition of a large amount of lithium salt to achieve the desired effect, and the addition of lithium salt will cause the positive electrode to become thicker and introduce unnecessary anion groups, thus affecting the battery's service life and cycle performance. Therefore, more battery cell companies hope to supplement lithium by pre-lithiation of the negative electrode of lithium batteries.

[0004] Negative electrode pre-lithiation and lithium replenishment can directly use metal lithium powder, lithium foil, lithium strip, etc. to achieve the effect of pre-lithiation. However, negative electrode pre-lithiation also has certain problems and limitations. For example, the pre-lithiation of negative electrode lithium replenishment is generally sufficient at 2μm to 5μm. Metal lithium is active in nature, so it has high requirements for the environment and needs to be operated in a dry room with a dew point below -40°C; secondly, metal lithium below 20μm is an ultra-thin lithium strip that cannot be self-supporting and requires a supporting film, which consumes a lot of film materials; thirdly, due to the processing technology, the evaporation or magnetron sputtering process is not suitable for industrialization due to its high cost. The industrial preparation of lithium film usually adopts the mechanical rolling process, and it is difficult to accurately control the thickness, and the equipment requirements are very high, which makes the pre-lithiation of negative electrode more difficult.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The object of the present invention is to provide a pre-lithiation device and a pre-lithiation method to solve or improve the above technical problems.

[0007] The present invention can be implemented like this:

[0008] In a first aspect, the present invention provides a pre-lithiation device, which includes a fixed roller, a first movable roller, a second movable roller, an initial pole piece unwinding device, a first base film unwinding device, a first lithium supplement material unwinding device, a pre-lithiation pole piece winding device and a first base film winding device;

[0009] The first movable roller and the second movable roller are respectively arranged above and below the fixed roller at intervals; the first movable roller cooperates with the fixed roller and has a first feed end and a first discharge end, the second movable roller cooperates with the fixed roller and has a second feed end and a second discharge end, and the first feed end and the second feed end are respectively located on the left and right sides of the fixed roller;

[0010] There is a first gap between the first movable roller and the fixed roller, so that the first base film and the first lithium supplement material can enter between the first movable roller and the fixed roller from the first feeding end and form the first lithium supplement material into the first lithium film under the rolling action and transfer to the surface of the fixed roller, and the first discharging end is used for discharging the first base film;

[0011] There is a second gap between the second movable roller and the fixed roller, so that the initial electrode sheet can enter between the second movable roller and the fixed roller from the second feeding end and be rolled and combined with the first lithium film transferred to the surface of the fixed roller to obtain a pre-lithiation electrode sheet after the upper surface is pre-lithiated. The second discharging end is used for discharging the pre-lithiation electrode sheet;

[0012] The first base film unwinding device and the first lithium supplement material unwinding device are both arranged at the first feed end, the first base film winding device is arranged at the first discharge end, the initial pole piece unwinding device is arranged at the second feed end, and the pre-lithium pole piece winding device is arranged at the second discharge end.

[0013] In an optional embodiment, the pre-lithiation equipment further includes a third movable roller, a second base film unwinding device, a second lithium supplement material unwinding device, and a second base film winding device;

[0014] The third movable roller is arranged below the second movable roller, the third movable roller cooperates with the second movable roller and has a third feeding end and a third discharging end, the third feeding end is on the same side as the first feeding end, and the third discharging end is on the same side as the first discharging end;

[0015] There is a third gap between the second movable roller and the third movable roller, so that the second base film and the second lithium supplement material can enter between the second movable roller and the third movable roller from the third feeding end and form a second lithium film and transfer the second lithium supplement material to the surface of the second movable roller to be rolled and combined with the electrode in the second gap to obtain a pre-lithiation electrode after the lower surface is pre-lithiated; the third discharging end is used for discharging the second base film;

[0016] The second base film unwinding device and the second lithium supplement material unwinding device are both arranged at the third feeding end, and the second base film winding device is arranged at the third discharging end.

[0017] In an optional embodiment, the pre-lithiation equipment further includes a tension device, and along the conveying direction, a tension device is provided at the rear end of each unwinding device and at the front end of each winding device.

[0018] In an optional embodiment, the tension of each tension device is independently adjusted by a pneumatic cylinder.

[0019] In an optional embodiment, the pre-lithiation equipment also includes a first surface density testing device and a second surface density testing device; along the conveying direction, the first surface density testing device is arranged at the front end of the second gap to test the surface density of the initial electrode before entering the second gap, and the second surface density testing device is arranged at the rear end of the second gap to test the surface density of the pre-lithiation electrode discharged from the second gap.

[0020] In an optional embodiment, the first base film and the second base film independently include at least one of PET, PP, PVC, steel strip, and aluminum strip, preferably a PET film, more preferably a PET film treated with an organic silicon polymer material on one side;

[0021] and / or, the release forces of the first base film and the second base film are independently 0 g to 30 g, preferably 0 g to 10 g;

[0022] And / or, the thickness of the first base film and the second base film are independently 30 μm to 100 μm, preferably 50 μm to 75 μm.

[0023] In an optional embodiment, the thickness of the first lithium supplement material and the second lithium supplement material are independently 100 μm to 2000 μm, preferably 200 μm to 1000 μm;

[0024] And / or, the peel strength between the first base film and the first lithium supplementing material is lower than 30 gf.

[0025] In an optional embodiment, the roller diameter of each movable roller and the fixed roller is independently 50 mm to 800 mm, preferably 100 mm to 200 mm;

[0026] And / or, the surfaces of the fixed roller and the second movable roller are both attached with a release agent material; preferably, the release agent material includes at least one of silicone oil, dimethyl silicone oil, modified silicone oil, organic silicon polymer material, graphite, acetylene black and synthetic grease;

[0027] And / or, each movable roller is independently provided with a hydraulic device;

[0028] And / or, the fixed roll and each movable roll are independently hollow rolls, and an oil cooling structure is provided inside the hollow roll;

[0029] And / or, under initial conditions, the first gap, the second gap and the third gap are independently 5 mm to 20 mm, preferably 10 mm to 15 mm.

[0030] In a second aspect, the present invention provides a pre-lithiation method, using a pre-lithiation device according to any one of the above embodiments to perform the following operations:

[0031] The first base film and the first lithium supplement material are introduced into the first gap from the first feeding end and the first lithium supplement material is formed into a first lithium film under the action of rolling and transferred to the surface of the fixed rolling roller; the first base film is discharged from the first discharging end;

[0032] The initial electrode sheet enters the second gap from the second feeding end and is rolled and combined with the first lithium film transferred to the surface of the fixed roller, and the pre-lithiation electrode sheet with the upper surface pre-lithiation treatment is obtained and then discharged from the second discharging end.

[0033] In an optional embodiment, when the pre-lithiation equipment also includes a third active roller, a second base film unwinding device, a second lithium-supplementing material unwinding device and a second base film winding device, the pre-lithiation method also includes: before the pre-lithiation electrode sheet is discharged, the second base film and the second lithium-supplementing material are introduced into the third gap from the third feed end and under the action of rolling, the second lithium-supplementing material forms a second lithium film and is transferred to the surface of the second active roller, and the second base film is discharged from the third discharge end; the electrode sheet in the second gap is rolled together with the second lithium film transferred to the surface of the second active roller to obtain a pre-lithiation electrode sheet after the lower surface is pre-lithiation treated; the pre-lithiation electrode sheet after both the upper and lower surfaces are pre-lithiation treated is discharged from the second discharge end.

[0034] In an optional embodiment, the feeding angle between the first base film and the first lithium supplement material at the first feeding end is 15° to 75°, preferably 45° to 60°;

[0035] And / or, the feeding angle between the second base film and the second lithium supplement material at the third feeding end is 15° to 75°, preferably 45° to 60°;

[0036] and / or, the thickness of the first lithium film and the second lithium film independently does not exceed 10 μm, preferably does not exceed 5 μm;

[0037] And / or, the surface release force of the fixed roller and the surface release force of the second movable roller are both 0g to 10g higher than the release force of the first base film, and the peeling strength between the fixed roller and the first lithium film is lower than the peeling strength between the first lithium film and the initial electrode.

[0038] The beneficial effects of the present invention include:

[0039] The pre-lithiation equipment provided by the present invention has a simple structure, is easy to operate and has a low cost. By adopting the pre-lithiation equipment to perform pre-lithiation treatment on the negative electrode pole piece, the pole piece can be pre-lithiated while the lithium-supplementing material is rolled. On the one hand, the production efficiency is effectively improved, the processing time is shortened, and the production cost is saved. On the other hand, the transportation, storage and processing risks of the lithium-supplementing material are effectively reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 A schematic diagram of the structure of the pre-lithiation device provided by the present invention;

[0042] Figure 2 A schematic diagram of the working principle of the hydraulic mechanism provided on each roller in the pre-lithiation device provided by the present invention;

[0043] Figure 3 This is a schematic structural diagram of the pre-lithium electrode provided by the present invention.

[0044] Icons: 10-first movable roller; 20-fixed roller; 30-second movable roller; 40-third movable roller; 51-first base film unwinding device; 52-second base film unwinding device; 53-first lithium supplement material unwinding device; 54-second lithium supplement material unwinding device; 55-initial pole piece unwinding device; 56-first base film winding device; 57-second base film winding device; 58-pre-lithium pole piece winding device; 60-tension device; 71-first surface density testing device; 72-second surface density testing device; 81-first base film; 82-first lithium supplement material; 83-second base film; 84-second lithium supplement material; 85-initial pole piece; 86-pre-lithium pole piece; 861-pre-lithiation upper lithium layer; 862-pole piece layer; 863-pre-lithiation lower lithium layer. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0046] The pre-lithiation device and pre-lithiation method provided by the present invention are described in detail below.

[0047] In the following description, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, or are the orientation or position relationship in which the invented product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply 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 limiting the present invention. In addition, the terms "first", "second", "third", etc., etc., are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0048] In addition, the terms "horizontal" and "vertical" do not mean that the components must be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0049] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" 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 components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0050] The present invention provides a pre-lithiation device, please refer to Figure 1 The pre-lithiation equipment includes a fixed roller 20, a first movable roller 10, a second movable roller 30, an initial pole piece unwinding device 55, a first base film unwinding device 51, a first lithium supplement material unwinding device 53, a pre-lithiation pole piece winding device 58 and a first base film winding device 56.

[0051] The first movable roller 10 and the second movable roller 30 are respectively arranged above and below the fixed roller 20; the first movable roller 10 and the fixed roller 20 cooperate and have a first feed end and a first discharge end, the second movable roller 30 and the fixed roller 20 cooperate and have a second feed end and a second discharge end, and the first feed end and the second feed end are respectively located on the left and right sides of the fixed roller 20.

[0052] There is a first gap between the first movable roller 10 and the fixed roller 20, so that the first base film 81 and the first lithium supplement material 82 can enter between the first movable roller 10 and the fixed roller 20 from the first feeding end and form a first lithium film and transfer it to the surface of the fixed roller 20 under the rolling action. The first discharging end is used for discharging the first base film 81.

[0053] There is a second gap between the second movable roller 30 and the fixed roller 20 to allow the initial electrode 85 to enter between the second movable roller 30 and the fixed roller 20 from the second feed end and be rolled and combined with the first lithium film transferred to the surface of the fixed roller 20 to obtain a pre-lithiation electrode 86 after the upper surface is pre-lithiated. The second discharge end is used to discharge the pre-lithiation electrode 86.

[0054] The first base film unwinding device 51 and the first lithium supplement material unwinding device 53 are both arranged at the first feed end, the first base film winding device 56 is arranged at the first discharge end, the initial electrode unwinding device 55 is arranged at the second feed end, and the pre-lithium electrode winding device 58 is arranged at the second discharge end.

[0055] The above structure can realize the single-sided pre-lithiation operation of the initial electrode 85 .

[0056] Furthermore, when pre-lithiation operation is required for both sides of the initial electrode 85 , the pre-lithiation equipment further includes a third movable roller 40 , a second base film unwinding device 52 , a second lithium supplement material unwinding device 54 and a second base film winding device 57 .

[0057] The third movable roller 40 is arranged below the second movable roller 30, and the third movable roller 40 cooperates with the second movable roller 30 and has a third feed end and a third discharge end. The third feed end is on the same side as the first feed end, and the third discharge end is on the same side as the first discharge end.

[0058] There is a third gap between the second movable roller 30 and the third movable roller 40, so that the second base film 83 and the second lithium supplement material 84 can enter between the second movable roller 30 and the third movable roller 40 from the third feeding end and under the rolling action, the second lithium supplement material 84 forms a second lithium film and is transferred to the surface of the second movable roller 30 to be rolled and combined with the electrode in the second gap to obtain a pre-lithiation electrode 86 after the lower surface is pre-lithiated; the third discharging end is used for discharging the second base film 83.

[0059] The fixed roller 20 can be fixed on the frame, and it only has the function of rotating. The first movable roller 10, the second movable roller 30 and the third movable roller 40 are rollers that can move up and down and rotate around the axis. During operation, the rotation direction of the fixed roller 20 is consistent with the rotation direction of the third movable roller 40, the rotation direction of the first movable roller 10 is consistent with the rotation direction of the second movable roller 30, and the rotation direction of the first movable roller 10 is opposite to the rotation direction of the fixed roller 20. The fixed roller 20 and the second movable roller 30 both play the role of transfer, the fixed roller 20 is used to transfer the first lithium film, and the second movable roller 30 is used to transfer the second lithium film.

[0060] Furthermore, the pre-lithiation device further includes a tension device 60. Along the conveying direction, the rear end of each unwinding device and the front end of each winding device are provided with a tension device 60. The tension of each tension device 60 can be independently adjusted by a pneumatic cylinder, and can also be adjusted by a hydraulic cylinder or the like. By adjusting the tension of each tension device 60, it is ensured that the tension does not affect the product quality.

[0061] Furthermore, the above-mentioned pre-lithiation equipment also includes a first surface density testing device 71 and a second surface density testing device 72. Along the conveying direction, the first surface density testing device 71 is arranged at the front end of the second gap to test the surface density of the initial electrode 85 before entering the second gap, and the second surface density testing device 72 is arranged at the rear end of the second gap to test the surface density of the pre-lithiation electrode 86 discharged from the second gap.

[0062] The first surface density testing device 71 may include two sub-surface density testing devices, which are respectively used to test the surface density of the upper surface and the lower surface of the initial electrode 85. Similarly, the second surface density testing device 72 may also include two sub-surface density testing devices, which are respectively used to test the surface density of the upper surface and the lower surface of the pre-lithium electrode 86.

[0063] Thickness detection can also be achieved through surface density testing.

[0064] In some optional embodiments, the first base film 81 and the second base film 83 may independently include at least one of PET, PP, PVC, steel strips and aluminum strips. In some preferred embodiments, the first base film 81 and the second base film 83 are independently PET films, more preferably PET films with one side treated with organic silicon polymer materials.

[0065] In some optional embodiments, the release forces of the film materials of the first base film 81 and the second base film 83 are independently 0g to 30g, such as 0g, 5g, 10g, 15g, 20g, 25g or 30g, or other values ​​within the range of 0g to 30g. In some preferred embodiments, the release forces of the film materials of the first base film 81 and the second base film 83 are independently 0g to 10g.

[0066] In some optional embodiments, the thickness of the first base film 81 and the second base film 83 are independently 30 μm to 100 μm, such as 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm, etc., and can also be other values ​​within the range of 30 μm to 100 μm. In some preferred embodiments, the thickness of the first base film 81 and the second base film 83 are independently 50 μm to 75 μm. The above thickness range can make the base film have good support capacity.

[0067] In some optional embodiments, the thickness of the first lithium supplement material 82 and the second lithium supplement material 84 are independently 100 μm to 2000 μm, such as 100 μm, 200 μm, 500 μm, 800 μm, 1000 μm, 1200 μm, 1500 μm, 1800 μm or 2000 μm, etc., and can also be other values ​​within the range of 200 μm to 2000 μm. In some preferred embodiments, the thickness of the first lithium supplement material 82 and the second lithium supplement material 84 are independently 300 μm to 1000 μm. The first lithium supplement material 82 and the second lithium supplement material 84 can be lithium strips, and their widths can be set as needed.

[0068] In some optional embodiments, the peel strength between the first base film 81 and the first lithium supplement material 82 is lower than 30 gf. By controlling the peel strength, it is possible to ensure that the first lithium film can be attached to the surface of the fixed roller 20.

[0069] In some optional embodiments, the roller diameter of each movable roller and the fixed roller 20 can be independently 50 mm to 800 mm, such as 50 mm, 100 mm, 200 mm, 300 mm, 400 mm, 500 mm, 600 mm, 700 mm or 800 mm, or other values ​​within the range of 50 mm to 800 mm. In some preferred embodiments, the roller diameter of each movable roller and the fixed roller 20 can be independently 100 mm to 200 mm.

[0070] In some optional embodiments, the surface release force of the fixed roller 20 and the surface release force of the second movable roller 30 are both 0g to 10g higher than the release force of the first base film 81, and at the same time ensure that the peeling strength between the fixed roller 20 and the first lithium film is lower than the peeling strength between the first lithium film and the initial electrode sheet 85 to avoid the negative electrode powder from adhering to the fixed roller 20.

[0071] The surfaces of the fixed roller 20 and the second movable roller 30 are both adhered with release agent materials. Exemplarily, the release agent materials include at least one of silicone oil, dimethyl silicone oil, modified silicone oil, organic silicon polymer material, graphite, acetylene black and synthetic grease.

[0072] In some optional embodiments, each movable roller is independently provided with a hydraulic device to control the fit of the roller gaps (which can be understood as each gap) between the rollers.

[0073] In some optional embodiments, under the initial condition, the first gap, the second gap and the third gap can be independently 5 mm to 20 mm, such as 5 mm, 8 mm, 10 mm, 12 mm, 15 mm, 18 mm or 20 mm, or other values ​​within the range of 5 mm to 20 mm. In some preferred embodiments, under the initial condition, the first gap, the second gap and the third gap can be independently 10 mm to 15 mm.

[0074] The second gap between the fixed roller 20 and the second movable roller 30 is used to control the target thickness of the pre-lithiation electrode.

[0075] Reference Figure 2 , the hydraulic mechanism of the second movable roller 30 has an extrusion force F3 after overcoming the self-weight of the second movable roller 30. At the same time, due to the closure between the second movable roller 30 and the third movable roller 40, the second base film 83 and the second lithium supplement material 84 are rolled, so that the thickness of the obtained second lithium film reaches the target requirement. The hydraulic mechanism of the third movable roller 40 applies an extrusion force F4 upward, that is, by adjusting the three pressure values ​​of F2, F3, and F4, the pressure values ​​between the fixed roller 20 and the second movable roller 30, and between the second movable roller 30 and the third movable roller 40 can be obtained. Similarly, the hydraulic mechanism of the first movable roller 10 applies a downward extrusion force F1 to adjust the thickness of the first lithium film. When the equipment is operating normally, because of the extrusion of different forces, when the extrusion force F required between the fixed roller 20 and the second movable roller 30 is exactly the force F3 during the initial roller gap adjustment, when the equipment starts to operate, the hydraulic mechanism of the second movable roller 30 will apply a force equivalent to F4 to offset the force F4 applied due to rolling the lithium film. For example, when the pre-lithiation device is operating normally, the extrusion force applied by the third movable roller 40 is 20t, and the combined force of the extrusion force required between the fixed roller 20 and the second movable roller 30 and the force to overcome the roller's deadweight is 10t. At this time, the hydraulic mechanism set by the second movable roller 30 applies F2 of 10t downward to offset the impact of the extrusion force applied by the rolling lithium film. By calculating the amount of lithium required for the pre-lithiation of the pole piece, the hydraulic mechanism adjusts the roller gap of the lithium film rolling, and can achieve differentiated and accurate pre-lithiation of both sides of the pole piece.

[0076] In some embodiments, the effective working range of each roller can be 100 mm to 700 mm, such as 100 mm, 200 mm, 300 mm, 400 mm, 500 mm, 600 mm or 700 mm, etc., or other values ​​within the range of 100 mm to 700 mm. In some preferred embodiments, the effective working range of each roller can be 200 mm to 450 mm. Preferably, the second movable roller 30 is longer than the fixed roller 20, such as about 200 mm longer, to facilitate the installation of the hydraulic device.

[0077] In some optional embodiments, in order to ensure that the heat generated by the rollers in continuous production does not affect the product, the fixed roller 20 and each movable roller are independently hollow rollers, and an oil circuit cooling structure is provided inside the hollow rollers to ensure that during the rolling process, the lithium membrane will not generate heat due to the long-term operation of the rollers, causing lithium membrane quality problems.

[0078] Accordingly, the present invention also provides a pre-lithiation method, comprising: using the above-mentioned pre-lithiation device to perform the following operations:

[0079] The first base film 81 and the first lithium supplement material 82 are introduced into the first gap from the first feeding end and the first lithium supplement material 82 is formed into a first lithium film under the action of rolling and transferred to the surface of the fixed roller 20; the first base film 81 is discharged from the first discharging end;

[0080] The initial electrode 85 enters the second gap from the second feeding end and is rolled and combined with the first lithium film transferred to the surface of the fixed roller 20 to obtain a pre-lithiation electrode 86 with a pre-lithiation treatment on the upper surface, and then discharged from the second discharging end.

[0081] Furthermore, when the pre-lithiation equipment also includes a third active roller 40, a second base film unwinding device 52, a second lithium supplement material unwinding device 54 and a second base film winding device 57, the pre-lithiation method also includes: before the pre-lithiation electrode sheet 86 is discharged, the second base film 83 and the second lithium supplement material 84 are introduced into the third gap from the third feed end and under the action of rolling, the second lithium supplement material 84 forms a second lithium film and is transferred to the surface of the second active roller 30, and the second base film 83 is discharged from the third discharge end; the electrode sheet in the second gap is rolled together with the second lithium film transferred to the surface of the second active roller 30 to obtain the pre-lithiation electrode sheet 86 after the lower surface is pre-lithiation treated; the pre-lithiation electrode sheet 86 after the upper and lower surfaces are pre-lithiation treated is discharged from the second discharge end.

[0082] In some optional embodiments, the feeding angle between the first base film 81 and the first lithium supplement material 82 at the first feeding end can be 15° to 75°, such as 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70° or 75°, etc., or other values ​​within the range of 15° to 75°. In some more preferred embodiments, the feeding angle between the first base film 81 and the first lithium supplement material 82 at the first feeding end is 45° to 60°.

[0083] Similarly, the feeding angle between the second base film 83 and the second lithium supplement material 84 at the third feeding end can be 15° to 75°, such as 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70° or 75°, etc., or other values ​​within the range of 15° to 75°. In some preferred embodiments, the feeding angle between the second base film 83 and the second lithium supplement material 84 at the third feeding end is 45° to 60°.

[0084] By controlling the above angle range, it is possible to avoid strong adsorption of static electricity on the surface of the base film and the lithium supplement material, and to avoid the lithium film being adsorbed on the base film due to the influence of the peeling angle after the lithium supplement material is rolled.

[0085] In some optional embodiments, the thickness of the first lithium film and the second lithium film independently does not exceed 10 μm, preferably does not exceed 5 μm.

[0086] In some specific embodiments, the lithium pre-supplementation operation can be performed in the following manner:

[0087] S1: Measure the surface density of the initial pole piece 85 by the first surface density testing device 71. For example, the surface density of the pole piece coating is P1=80 g / m 2 The target thickness of the initial electrode 85 after pre-lithiation treatment is 140 μm. By controlling the roller gap and pressure between the fixed roller 20 and the second movable roller 30, the roller gap is closed so that the thickness of the pre-lithiation electrode 86 discharged from the second discharge end reaches the target thickness.

[0088] S2: After the gap between the fixed roller 20 and the second movable roller 30 is fixed, taking the base film thickness of 75 μm and the lithium supplement material thickness of 300 μm as an example, after the rollers are closed, the gap between the first movable roller 10 and the fixed roller 20 is set to 70 μm-80 μm, and the gap between the rollers is adjusted by theoretically calculating the thickness of the lithium film according to the amount of lithium required for pre-lithiation of the electrode; similarly, the third gap between the second movable roller 30 and the third movable roller 40 is set to obtain a lithium film of 0 μm-10 μm (when pre-lithiation on one side, it can be regarded as a lithium film with a thickness of 0 μm and a thickness of not 0 μm on the other side), preferably a lithium film of 0 μm-5 μm, so that the surface density of the lithium layer after pre-lithiation is P2=0 g / m 2 ~2.67g / m 2 (When one side is pre-lithiated, it can be regarded as a lithium layer with a surface density of 0g / m 2 , the surface density of the other lithium layer is not 0g / m 2). Since the surface of the base film has a polymer coating, the rolled lithium film adheres to the fixed roller 20 and the second movable roller 30. According to different requirements of the pole piece, the roller gap can be adjusted by the hydraulic mechanism so that the thickness of the pre-lithiation lithium layer of the pole piece can be adjusted according to the requirements.

[0089] S3: The lithium film attached to the fixed roller 20 and the second movable roller 30 passes through the second gap. Due to rolling, the lithium film attached to the roller surface is transferred to the electrode. The surface density P=P1+2×P2 of the electrode after pre-lithiation is measured by the second surface density testing device 72. The gap between the rollers is adjusted according to the required thickness, so that the electrode is pre-lithiated according to the target requirement.

[0090] S4: After the pre-lithiation of the electrode is completed, the pre-lithiation electrode 86 is collected.

[0091] Continuing from the above, the present invention integrates rolling and pre-lithiation, that is, the negative electrode pre-lithiation rolling and transfer are integrated, and the transfer is carried out while rolling, thereby avoiding the waste of film materials caused by double-sided coating in the traditional coating rolling process; at the same time, the rolling and pre-lithiation are carried out simultaneously, which also reduces the process steps of pre-lithiation. The operating principle includes: first, the base film, lithium supplement material, and initial pole piece 85 are threaded and fixed according to the set path; then the parameters of each roller gap (gap) are set, wherein the roller gap between other active rollers is set based on the fixed roller 20; finally, after the roller gap is set, the equipment is started. By calculating the consumption of lithium supplement material and monitoring the surface density, the roller gap is fine-tuned to make the lithium surface density of the pre-lithiation pole piece after the lithium film transfer within the target range (0g / m 2 ~2.67g / m 2 ) to achieve the required precise pre-lithiation. When the equipment is working normally, the rolled lithium film is attached to the fixed roller 20 and the second movable roller 30. When working continuously, the equipment running speed is adjusted through the matching motor equipment to achieve roll-to-roll rapid pre-lithiation of the negative electrode material.

[0092] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0093] Example 1

[0094] The present embodiment provides a pre-lithiation device, which includes a fixed roller 20, a first movable roller 10, a second movable roller 30, a third movable roller 40, a first base film unwinding device 51, a second base film unwinding device 52, a first lithium supplement material unwinding device 53, a second lithium supplement material unwinding device 54, an initial electrode unwinding device 55, a first base film winding device 56, a second base film winding device 57, a pre-lithium electrode winding device 58, a tension device 60, a first surface density testing device 71, and a second surface density testing device 72.

[0095] From top to bottom, the first movable roller 10, the fixed roller 20, the second movable roller 30 and the third movable roller 40 are arranged in sequence. The first movable roller 10 cooperates with the fixed roller 20 and has a first feed end and a first discharge end, the second movable roller 30 cooperates with the fixed roller 20 and has a second feed end and a second discharge end, and the third movable roller 40 cooperates with the second movable roller 30 and has a third feed end and a third discharge end. The first feed end and the third feed end are located on the left side of the fixed roller 20, the second feed end is located on the right side of the fixed roller 20, the first discharge end and the third discharge end are located on the right side of the fixed roller 20, and the second discharge end is located on the left side of the fixed roller 20.

[0096] The first base film unwinding device 51 and the first lithium supplement material unwinding device 53 are both arranged at the first feed end, and the first base film winding device 56 is arranged at the first discharge end; the initial electrode unwinding device 55 is arranged at the second feed end, and the pre-lithium electrode winding device 58 is arranged at the second discharge end; the second base film unwinding device 52 and the second lithium supplement material unwinding device 54 are both arranged at the third feed end, and the second base film winding device 57 is arranged at the third discharge end.

[0097] There is a first gap between the first movable roller 10 and the fixed roller 20 , there is a second gap between the second movable roller 30 and the fixed roller 20 , and there is a third gap between the second movable roller 30 and the third movable roller 40 .

[0098] The fixed roller 20 is fixed on the frame, and the first movable roller 10, the second movable roller 30 and the third movable roller 40 are rollers that can move up and down and rotate around the axis. During operation, the fixed roller 20 and the third movable roller 40 rotate clockwise, and the first movable roller 10 and the second movable roller 30 rotate counterclockwise.

[0099] Along the conveying direction, the rear end of each unwinding device and the front end of each winding device are provided with a tension device 60 adjusted by a pneumatic cylinder. The first surface density test device 71 is provided at the second feeding end, and the second surface density test device 72 is provided at the second discharging end. Each movable roller is independently provided with a hydraulic device. The fixed roller 20 and each movable roller are hollow rollers, and an oil circuit cooling structure is provided inside the hollow rollers.

[0100] Example 2

[0101] This embodiment provides a pre-lithiation method, which is performed using the pre-lithiation equipment provided in Example 1.

[0102] Pre-lithiation operations include:

[0103] S1: Threading: thread each base film, each lithium supplement material (lithium belt), and initial pole piece 85 along the corresponding path according to the structural position set by the pre-lithiation equipment. Under the initial condition, the first gap, the second gap, and the third gap are all 10 mm.

[0104] S2: The surface density (80 g / m 2 ), the target thickness of the pre-lithium electrode 86 is 140μm, and the second gap between the fixed roller 20 and the second movable roller 30 is adjusted to 140μm by the hydraulic mechanism. The electrode has a certain amount of compression after coating, so this thickness is set as the target thickness of the electrode, and the actual setting value can be fine-tuned according to actual conditions.

[0105] S3: After the second gap is fixed, taking the thickness of each base film as 75 μm (the release force of each base film is selected as 25g-30g) and the thickness of each lithium strip as 200 μm as an example, after the rollers are closed, the first gap between the first movable roller 10 and the fixed roller 20 is set to 80 μm, and the roller gap is adjusted according to the required pre-lithiation lithium film thickness; similarly, the third gap between the second movable roller 30 and the third movable roller 40 is set to 80 μm, and the first and second lithium films of 5 μm are obtained, so that the upper and lower lithium layer densities after pre-lithiation are both 2.67 g / m 2 The above-mentioned base films are all PET films whose surfaces are treated with organic silicon polymer materials, and the rolled first lithium film and the second lithium film are attached to the fixed roller 20 and the second movable roller 30 respectively.

[0106] S4: The first lithium film and the second lithium film on the fixed roller 20 and the second movable roller 30 are transferred to the initial electrode 85 due to rolling when passing through the gap between the rollers. The surface density of the electrode after pre-lithiation can be measured by the second surface density testing device 72. The gap between the rollers is adjusted according to the required thickness, so that the electrode can be pre-lithiated according to the target requirements.

[0107] The peeling strength between the base film and the lithium supplement material is lower than 30gf; the roller diameters of the movable rollers and the fixed roller 20 are both 200mm; the feeding angle between the first base film 81 and the first lithium supplement material 82 at the first feeding end is 50°, and the feeding angle between the second base film 83 and the second lithium supplement material 84 at the third feeding end is 50°; the surface release force of the fixed roller 20 and the surface release force of the second movable roller 30 are both 10g higher than the release force of the first base film 81, and the peeling strength between the fixed roller 20 and the first lithium film is lower than the peeling strength between the first lithium film and the initial electrode 85. The same is true for the second lithium film.

[0108] After pre-lithiation, the electrode is as follows Figure 3As shown, from top to bottom, there are pre-lithiation upper lithium layer 861, pole piece layer 862 and pre-lithiation lower lithium layer 863. The surface density of pre-lithiation upper lithium layer 861 and the surface density of pre-lithiation lower lithium layer 863 can be adjusted according to the requirements of the pole piece by adjusting the gap between the first movable roller 10 and the fixed roller 20, and the gap between the second movable roller 30 and the third movable roller 40. After pre-lithiation, the lithium film is evenly attached to the surface of the pole piece. If the surface density monitoring is qualified, the pre-lithiation is completed, and the pre-lithiation pole piece 86 is collected.

[0109] Example 3

[0110] The difference between this embodiment and embodiment 2 is that in S2, the release force of the film material of each base film is selected to be 4g.

[0111] Example 4

[0112] The difference between this embodiment and embodiment 2 is that in S2, the release force of the film material of each base film is selected to be 15g.

[0113] In summary, the solution provided by the present invention has at least the following advantages:

[0114] (1) Convenient operation: The pre-lithiation equipment has a simple structure, convenient operation and high flexibility;

[0115] (2) Cost saving: The pre-lithiation equipment adopts single-film rolling during film rolling, which saves two layers of film materials and directly reduces the cost of lithium film production;

[0116] (3) Reduce process steps: The pre-lithiation equipment realizes the pre-lithiation of the electrode during the coating and rolling, which reduces the secondary threading and saves time and process steps;

[0117] (4) Reduce risks: The roll-to-roll preparation of pre-lithiation electrodes reduces the intermediate steps, avoids the denaturation of lithium membranes due to production and transportation, and realizes the industrialized rapid pre-lithiation production of electrodes.

[0118] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A pre-lithiation device, characterized in that: It includes a fixed roller, a first movable roller, a second movable roller, an initial pole piece unwinding device, a first base film unwinding device, a first lithium supplement material unwinding device, a pre-lithium pole piece winding device and a first base film winding device; The first movable roller and the second movable roller are respectively arranged above and below the fixed roller at intervals; the first movable roller cooperates with the fixed roller and has a first feed end and a first discharge end, the second movable roller cooperates with the fixed roller and has a second feed end and a second discharge end, and the first feed end and the second feed end are respectively located on the left and right sides of the fixed roller; There is a first gap between the first movable roller and the fixed roller, so that the first base film and the first lithium supplement material can enter between the first movable roller and the fixed roller from the first feeding end, and under the rolling action, the first lithium supplement material forms a first lithium film and is transferred to the surface of the fixed roller, and the first discharging end is used for discharging the first base film; There is a second gap between the second movable roller and the fixed roller, so that the initial electrode sheet can enter between the second movable roller and the fixed roller from the second feeding end and be rolled and combined with the first lithium film transferred to the surface of the fixed roller to obtain a pre-lithiation electrode sheet with the upper surface pre-lithiation treated, and the second discharging end is used for discharging the pre-lithiation electrode sheet; The first base film unwinding device and the first lithium supplement material unwinding device are both arranged at the first feed end, the first base film winding device is arranged at the first discharge end, the initial pole piece unwinding device is arranged at the second feed end, and the pre-lithium pole piece winding device is arranged at the second discharge end.

2. The pre-lithiation device according to claim 1, characterized in that: The pre-lithiation equipment also includes a third movable roller, a second base film unwinding device, a second lithium supplement material unwinding device, and a second base film winding device; The third movable roller is arranged below the second movable roller, the third movable roller cooperates with the second movable roller and has a third feed end and a third discharge end, the third feed end is on the same side as the first feed end, and the third discharge end is on the same side as the first discharge end; There is a third gap between the second movable roller and the third movable roller, so that the second base film and the second lithium supplement material can enter between the second movable roller and the third movable roller from the third feed end, and under the rolling action, the second lithium supplement material forms a second lithium film and is transferred to the surface of the second movable roller to be rolled and combined with the pole piece in the second gap, so as to obtain a pre-lithiation pole piece after the lower surface is pre-lithiated; The third discharge end is used for discharging the second base film; The second base film unwinding device and the second lithium supplement material unwinding device are both arranged at the third feeding end, and the second base film winding device is arranged at the third discharging end.

3. The pre-lithiation device according to claim 1 or 2, characterized in that: The pre-lithiation equipment further includes a tension device, and along the conveying direction, the rear end of each unwinding device and the front end of each winding device are provided with a tension device; Preferably, the tension of each tension device is independently adjusted by a pneumatic cylinder.

4. The pre-lithiation device according to claim 1 or 2, characterized in that: The pre-lithiation equipment also includes a first surface density testing device and a second surface density testing device. Along the conveying direction, the first surface density testing device is arranged at the front end of the second gap to test the surface density of the initial electrode before entering the second gap, and the second surface density testing device is arranged at the rear end of the second gap to test the surface density of the pre-lithium electrode discharged from the second gap.

5. The pre-lithiation device according to claim 2, characterized in that: The first base film and the second base film independently include at least one of PET, PP, PVC, steel strip, and aluminum strip, preferably a PET film, more preferably a PET film treated with an organic silicon polymer material on one side; and / or, the release forces of the first base film and the second base film are independently 0g to 30g, preferably 0g to 10g; And / or, the thickness of the first base film and the second base film is independently 30 μm to 100 μm, preferably 50 μm to 75 μm.

6. The pre-lithiation device according to claim 2, characterized in that: The thickness of the first lithium supplement material and the second lithium supplement material are independently 100 μm to 2000 μm, preferably 200 μm to 1000 μm; And / or, the peel strength between the first base film and the first lithium supplementing material is lower than 30 gf.

7. The pre-lithiation device according to claim 2, characterized in that: The roller diameter of each movable roller and the fixed roller is independently 50 mm to 800 mm, preferably 100 mm to 200 mm; And / or, the surfaces of the fixed roller and the second movable roller are both attached with a release agent material; preferably, the release agent material includes at least one of silicone oil, dimethyl silicone oil, modified silicone oil, organic silicon polymer material, graphite, acetylene black and synthetic grease; And / or, each movable roller is independently provided with a hydraulic device; And / or, the fixed roller and each movable roller are independently hollow rollers, and an oil circuit cooling structure is provided inside the hollow rollers; And / or, under initial conditions, the first gap, the second gap and the third gap are independently 5 mm to 20 mm, preferably 10 mm to 15 mm.

8. A pre-lithiation method, characterized in that: The following operations are performed using the pre-lithiation device as described in any one of claims 1 to 7: The first base film and the first lithium supplement material are introduced into the first gap from the first feeding end and the first lithium supplement material is formed into the first lithium film and transferred to the surface of the fixed roller under the action of rolling; the first base film is discharged from the first discharging end; The initial electrode sheet is introduced into the second gap from the second feed end and rolled together with the first lithium film transferred to the surface of the fixed roller, and a pre-lithiation electrode sheet with a pre-lithiation treatment on the upper surface is obtained and then discharged from the second discharge end.

9. The pre-lithiation method according to claim 8, characterized in that: When the pre-lithiation equipment further includes a third movable roller, a second base film unwinding device, a second lithium supplement material unwinding device, and a second base film winding device, The pre-lithiation method also includes: before the pre-lithiation electrode sheet is discharged, the second base film and the second lithium supplement material are introduced into the third gap from the third feed end and under the action of rolling, the second lithium supplement material forms a second lithium film and is transferred to the surface of the second active roller, and the second base film is discharged from the third discharge end; the electrode sheet in the second gap is rolled together with the second lithium film transferred to the surface of the second active roller to obtain the pre-lithiation electrode sheet with the lower surface pre-lithiation treated; the pre-lithiation electrode sheet with the upper and lower surfaces pre-lithiation treated is discharged from the second discharge end.

10. The pre-lithiation method according to claim 9, characterized in that: The feeding angle between the first base film and the first lithium supplement material at the first feeding end is 15° to 75°, preferably 45° to 60°; And / or, the feeding angle between the second base film and the second lithium supplement material at the third feeding end is 15° to 75°, preferably 45° to 60°; and / or the thickness of the first lithium film and the second lithium film independently does not exceed 10 μm, preferably does not exceed 5 μm; And / or, the surface release force of the fixed roller and the surface release force of the second movable roller are both 0g to 10g higher than the release force of the first base film, and the peeling strength between the fixed roller and the first lithium film is lower than the peeling strength between the first lithium film and the initial electrode.

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