Winding type vacuum coating equipment

Abstract

The invention discloses winding type vacuum coating equipment which comprises a first magnetic control coating chamber, a second magnetic control coating chamber, a first evaporation chamber, a second evaporation chamber and a bias voltage generating device. And front adjusting rollers, coating rollers and rear adjusting rollers are sequentially arranged in the first and second magnetic control coating chambers and the first and second evaporation chambers. In a magnetron coating chamber, depositing a compact basic film layer on the flexible film through magnetron sputtering coating; in an evaporation chamber, a growth film layer is deposited over the base film layer by evaporation coating. And cooling liquid is introduced into the film coating roller to cool the flexible film. The bias voltage generating device enables the film coating roller and the at least one adjusting roller to have bias voltage, so that the flexible film is tightly attached to the surface of the film coating roller when winding around the film coating roller, and a better cooling effect is achieved. Auxiliary electric field generating devices are arranged on the opposite sides of the film moving downstream side of the film coating roller, and when the flexible film moves to the downstream side area and needs to be separated from the surface of the film coating roller, auxiliary electric fields generated by the auxiliary electric field generating devices play a role in assisting roller separation.

Description

Technical Field

[0001] The present invention belongs to the technical field of vacuum coating, and in particular relates to a roll-to-roll vacuum coating device for preparing a composite current collector conductive film layer. Background Art

[0002] Currently, most industrialized lithium battery electrode sheets use metal foil as the current collector. However, the thick metal foil current collector hinders further improvement of lithium battery energy density. In recent years, a "sandwich" composite current collector has emerged in related research fields. It uses thinner polymer films such as polyethylene terephthalate (PET) and polypropylene (PP) as the substrate, with metal coatings on both sides. This has the advantages of being lightweight, explosion-proof, and low-cost, providing feasibility for raising the energy density of lithium batteries to new heights.

[0003] In order to meet the conductivity requirements, the metal coating in the composite current collector needs to be about 1μm thick, which poses new challenges to the industrialization technology of the composite current collector. At present, vacuum evaporation coating technology is generally required to prepare high-quality metal coatings, but this will encounter difficulties in preparing thicker coatings on thinner flexible film substrates. On the one hand, if the evaporation power is increased or the film speed is reduced in order to increase the thickness of the deposited film, due to the poor temperature resistance of the flexible film, especially when encountering some ultra-thin flexible films that are more picky about the heating temperature, the flexible film substrate will often have quality problems such as heat deformation and wrinkling during the evaporation coating process; on the other hand, if multiple air-breaking coating processes are used, the efficiency will be reduced, and more importantly, it will cause oxidation problems for the metal coating, affecting the quality of the composite current collector. Therefore, a vacuum winding coating device that does not require air-breaking and can prepare thicker film layers on the front and back of a flexible film within one vacuum coating working cycle is urgently needed to be developed. Summary of the Invention

[0004] To address these issues, the present invention provides a roll-to-roll vacuum coating apparatus for preparing composite current collector conductive film layers. This roll-to-roll vacuum coating apparatus can produce thicker film layers on flexible films, even on the front and back surfaces of ultra-thin flexible base films, within a single vacuum coating cycle.

[0005] The roll-to-roll vacuum coating equipment of the present invention includes an unwinding chamber, a winding chamber, a first magnetron coating chamber, a first evaporation chamber, a second magnetron coating chamber, a second evaporation chamber, a bias generator, and a control center. Dividers are installed between the chambers, and adjacent chambers are connected by slits, allowing flexible film to pass through the slits between the chambers. The unwinding chamber is equipped with an unwinding roller, and the winding chamber is equipped with a winding roller. The first magnetron coating chamber, the second magnetron coating chamber, the first evaporation chamber, and the second evaporation chamber are each sequentially equipped with a front adjustment roller, a coating roller, and a rear adjustment roller. In the first and second magnetron coating chambers, magnetron targets are located opposite the coating rollers. The magnetron targets deposit a dense base film layer on the flexible film wrapped around the coating rollers through magnetron sputtering. In the first and second evaporation chambers, one or more evaporation sources are located below the coating rollers. The evaporation sources deposit a growth film layer on the base film layer of the flexible film through evaporation. Both the base film layer and the growth film layer are made of conductive materials, and together they form a conductive film layer. Coolant flows through each coating roller to cool the flexible film during magnetron sputtering and evaporation coating. A bias generating device applies a bias to each coating roller, and also applies a bias to at least one of the front and rear conditioning rollers, excluding the front conditioning rollers in the first and second magnetron coating chambers, to serve as a biased conditioning roller. The bias ensures that the flexible film adheres tightly to the surface of the coating roller as it winds around it, achieving a better cooling effect. A sensor is positioned downstream of the coating roller for online detection of the adhesion between the flexible film and the coating roller, transmitting a sensor signal reflecting the adhesion to a control center. An auxiliary electric field generating device is positioned on the opposite side of each coating roller from the downstream side of the film path. When the flexible film reaches this downstream region and needs to be separated from the coating roller surface, the auxiliary electric field generated by the auxiliary electric field generating device assists in removing the film from the roller.

[0006] Each coating roller has the same bias polarity, while the bias polarity of the bias adjustment roller is opposite to that of the coating rollers. The polarity of the auxiliary electric field is the same as the bias polarity of the coating rollers. The bias polarity of the coating rollers in the first and second magnetron coating chambers is the same as that of the coating rollers in the first and second evaporation chambers, resulting in charges of the same polarity distributed on the surfaces of each coating roller. Because the flexible film already has a conductive film layer in the base film or growth film stage when it passes over the front and rear adjustment rollers (except for the front adjustment rollers in the first and second magnetron coating chambers), the bias applied to the bias adjustment rollers causes the surface of the conductive film in contact with the bias adjustment rollers to have a charge of the opposite polarity to that distributed on the coating roller surfaces. The mutual attraction between the two charges of opposite polarity causes the flexible film to be attracted as it passes over the coating roller, closely adhering to the roller's surface. This improves cooling during magnetron sputtering or evaporation coating. In a preferred embodiment, at least the rear adjustment roller in the first magnetron coating chamber serves as a bias adjustment roller.

[0007] A dense base film layer with good organizational structure is first deposited on the surface of the flexible film by magnetron sputtering coating with strong particle kinetic energy, and then a thicker growth film layer is deposited on the base film layer at a high speed by evaporation coating. The base film layer with a good organizational structure is conducive to the growth film layer particles deposited on it to continue to grow along the organizational structure growth direction of the base film layer, forming a better film layer organization.

[0008] In the first magnetron coating chamber and the first evaporation chamber, a base film layer and a growth film layer are respectively deposited on the front side of the flexible film; in the second magnetron coating chamber and the second evaporation chamber, a base film layer and a growth film layer are respectively deposited on the back side of the flexible film; guide rollers are provided in each chamber; the flexible film is turned over when passing through the guide rollers in the first evaporation chamber and the second magnetron coating chamber.

[0009] In the first magnetron coating chamber and the second magnetron coating chamber, there are multiple magnetron targets arranged on the opposite side of the coating roller; there are more than two coating rollers arranged in the first evaporation chamber and the second evaporation chamber; the thickness of the conductive film layer is 0.3-2μm, among which the thickness of the base film layer is 30~200nm.

[0010] The auxiliary electric field generating device includes an electric field shield and multiple electric field generating units arranged in a matrix. Each unit is individually controlled by a control center, which provides online feedback control of the auxiliary electric field's strength and distribution based on sensor signals. The electric field shield limits the auxiliary electric field's area of ​​effect to the downstream region of each coating roller where the flexible film needs to separate from the coating roller surface, preventing the auxiliary electric field from affecting other areas where the flexible film needs to be in close contact with the coating roller. The auxiliary electric field exhibits a gradient intensity, with the intensity gradually increasing along the direction of the flexible film's travel.

[0011] When the sensor transmits the detected sensor signal to the control center, the control center determines whether the degree of fit between the flexible film and the coating roller is too high or too low based on the received sensor signal, and sends control instructions to each electric field generating unit to adjust the electric field strength generated by certain electric field generating units, increase or decrease the electric field strength of the auxiliary electric field, change the electric field distribution, and make the auxiliary electric field adaptively adjusted to the fit situation, thereby forming an effective auxiliary roller-off effect for the flexible film to detach from the roller surface.

[0012] The control center can also perform online feedback control of the auxiliary electric field based on the cooling effect of the flexible film on the coating roller. By adjusting the electric field strength and distribution of the auxiliary electric field, the position at which the flexible film separates from the coating roller can be adjusted online. If the control center determines that the flexible film is insufficiently cooled, the control center issues a control instruction to the auxiliary electric field generating device to reduce the electric field strength and change the electric field distribution, so that the position at which the flexible film separates from the coating roller is delayed within an appropriate range compared to the original separation position, thereby enhancing the cooling effect of the flexible film. If the control center determines that the flexible film is excessively cooled, the control center issues a control instruction to the auxiliary electric field generating device to increase the electric field strength and change the electric field distribution, so that the position at which the flexible film separates from the coating roller is advanced within an appropriate range compared to the original separation position, thereby weakening the cooling effect of the flexible film.

[0013] The bias voltage of each coating roller and bias regulating roller is individually controlled by online feedback from the control center according to the sensor signal.

[0014] When the control center determines that the cooling effect of the flexible film needs to be increased or decreased based on the received sensor signal, the control center sends a control instruction to the bias generating device to increase or decrease the bias of a coating roller and a bias adjustment roller close to the coating roller, and adjusts the fit between the flexible film and the surface of the coating roller online, so that the flexible film can obtain the required and stable cooling effect.

[0015] By carrying out multi-target magnetic sputtering coating in the first magnetron coating chamber and the second magnetron coating chamber, and arranging multiple evaporation modules including coating rollers and evaporation sources in the first evaporation chamber and the second evaporation chamber, and at the same time using online controllable bias to make the flexible film and the coating roller fit more closely, the flexible film obtains a better and more stable cooling effect, and overcomes the problems of the flexible film being easily deformed or even damaged by heat when using higher magnetron coating power and evaporation coating power. It is achieved that the preparation of thicker film layers, especially the preparation of film layers above 1μm, can be carried out within one vacuum coating working cycle without reducing the film travel speed of the flexible film.

[0016] The coating rollers in the second magnetron coating chamber and the second evaporation chamber are also coated with a heat-conducting, electrically insulating layer made from one of the following: aluminum oxide, aluminum nitride, silicon nitride, silicon oxide, zirconium oxide, or a resin. This layer prevents the charge on the front side of the flexible film from neutralizing the charge on the coating roller vacuum coating the back side, thus affecting the adhesion between the flexible film and the coating roller during vacuum coating on the front side.

[0017] An auxiliary electric field with gradually varying intensity is set to effectively assist the flexible film in detaching from the roller surface, overcoming the problem that the film layer is easily damaged when the flexible film is separated from the coating roller due to the large bias voltage. At the same time, through online feedback control of the bias voltage and auxiliary electric field of each roller, the production process of preparing a thicker conductive film layer by winding vacuum coating can be maintained continuously and stably without being affected by process fluctuations such as bias fluctuations caused by certain uncertain factors, thereby obtaining a highly consistent and high-quality flexible composite current collector film product.

[0018] The roll-to-roll vacuum coating apparatus of the present invention can be used to implement a method for preparing a composite current collector conductive film layer. The method uses a winding system to pass a flexible film through each chamber of the roll-to-roll vacuum coating apparatus, and performs a vacuum coating process on the front and back surfaces of the flexible film to prepare a conductive film layer. The vacuum coating process includes:

[0019] In the first magnetron coating chamber and the second magnetron sputtering coating chamber, the flexible film is sequentially wound around the front adjustment roller, the coating roller, and the rear adjustment roller; while winding around the coating roller, a dense base film layer is deposited on the flexible film by vacuum magnetron sputtering coating;

[0020] In the first evaporation chamber and the second evaporation chamber, the flexible film is sequentially wound around the front adjustment roller, the coating roller and the rear adjustment roller; when winding around the coating roller, a growth film layer is prepared on the surface of the base film layer on the flexible film by vacuum evaporation coating, thereby forming a conductive film layer on the flexible film.

[0021] The auxiliary electric field generator generates an auxiliary electric field in the downstream region where the flexible film passes through the magnetron coating roller and the evaporation coating roller. The polarity of the auxiliary electric field is the same as the bias voltage applied to the coating roller. The auxiliary electric field repels charges of the same polarity on the coating roller, causing the charge density on the coating roller opposite the auxiliary electric field generator to become sparser, weakening the attraction of the flexible film to this region. As a result, when the flexible film reaches this downstream region and needs to be released from the coating roller, the attraction between the flexible film and the coating roller weakens, reducing the degree of adhesion and facilitating the film's release from the roller surface. The auxiliary electric field assists in the film's release. The auxiliary electric field strength is lowest at the beginning of this downstream region. As it extends from the beginning toward the downstream region, the corresponding auxiliary electric field strength increases, repelling charges of the same polarity on the coating roller. Consequently, the charge density on the corresponding region becomes increasingly sparse, weakening the attraction of the flexible film to this region. At the pre-designed separation position where the flexible film is separated from the coating roller, the adsorption effect of the coating roller on the flexible film is weakest, and the flexible film is separated from the coating roller at this position.

[0022] The sensor's signal, reflecting the degree of adhesion, corresponds to the tension on the flexible film downstream of the coating roller. An increase in the sensor signal indicates increased tension, indicating a closer fit between the flexible film and the coating roller, resulting in better cooling. A decrease in the sensor signal indicates decreased tension, indicating a decreased fit between the flexible film and the coating roller, resulting in a reduced cooling effect. The sensor transmits the detected signal reflecting the degree of adhesion to the control center, which uses the signal to perform online feedback control of the auxiliary electric field's intensity and distribution. Specifically, when the sensor transmits the detected signal to the control center, the control center determines the degree of adhesion between the flexible film and the magnetron coating roller or evaporative coating roller based on the received signal and issues control instructions to each electric field generating unit, causing the auxiliary electric field generating unit to generate an auxiliary electric field with appropriate intensity and distribution in the downstream region of the coating roller, effectively assisting the flexible film in detaching from the roller surface. When the degree of contact between the flexible film and the coating roller is too high or too low, the control center will judge the situation and send control instructions to the auxiliary electric field generating device to adjust the electric field strength generated by certain electric field generating units, increase or decrease the electric field strength of the auxiliary electric field, and change the electric field distribution so that the auxiliary electric field can adapt to this situation and still maintain an effective auxiliary roller-off effect for the flexible film to separate from the roller surface.

[0023] The bias voltages on each coating roller and bias adjustment roller can vary. The control center can also provide online feedback control of the bias voltages of each coating roller and bias adjustment roller based on sensor signals. This allows for online adjustments to the contact between the flexible film and the coating roller surface to achieve the desired, stable cooling effect, as needed for specific process adjustments or when fluctuations occur during the vacuum coating process.

[0024] By applying a bias to the coating roller and the bias adjustment roller, the surfaces of the conductive film layer on the coating roller and the flexible film have charges of opposite polarity, which can make the flexible film fit more closely to the coating roller and better cool the flexible film, thus overcoming the problem that the flexible film is prone to thermal deformation or even thermal damage when preparing thicker film layers. However, the higher the bias and cooling effect, the better. When the flexible film is overcooled, on the one hand, the lower film forming temperature is not conducive to the formation of a good microstructure of the film layer, and on the other hand, the lower surface temperature is prone to condensation, affecting the product quality. Therefore, the present invention performs online feedback control on the bias and auxiliary electric field of each roller, so that the flexible film obtains an appropriate, required, and stable cooling effect, so that the winding vacuum coating process of preparing a thicker film layer on the flexible film can be stably implemented, and a high-quality flexible composite current collector film product is obtained.

[0025] The inventors have found that when the bias causes the flexible film to fit too tightly to the coating roller, the following phenomena may easily occur when the flexible film needs to be separated from the coating roller after it has passed through the coating roller: (1) when preparing a film layer on the back side of a flexible film on which a film layer has been prepared on the front side, in order to resist the large adsorption force between the flexible film and the coating roller, it is necessary to increase the pulling force on the flexible film, which may easily cause the front film layer in adsorption contact with the roller surface to be adhered and torn, and the flexible film to fall off; (2) when a large pulling force is applied to the flexible film to make it fall off the roller, the flexible film may be severely squeezed between the guide roller or the adjustment roller downstream of the coating roller, causing the newly prepared film layer to be This extrusion process causes damage such as extrusion cracks and wrinkles; (3) the separation position of the flexible film from the coating roller will be too late than the pre-planned separation position, resulting in a sharp angle bend between the flexible film after being removed from the roller and the flexible film remaining on the roller surface. This sharp angle bend will produce an irreversible crease on the flexible film, which will cause a microscopic height difference in the composite current collector. The thickness of the active material to be subsequently coated on the composite current collector is mostly less than 100 microns. Therefore, the existence of the height difference caused by this crease will cause the thickness of the active material coated near the crease to be uneven, resulting in different expansion volumes of the active material, which will bury the hidden dangers of accidents such as electrode sheet rupture. When the bias voltage is insufficient, not only will the flexible film be unable to obtain sufficient cooling from the coating roller, but the flexible film will also separate from the coating roller in advance, causing local film speed fluctuations in the winding system, bringing uncertain fluctuation factors to the stability of the winding vacuum coating process, and thus affecting the stability of the quality of the flexible film product. During the vacuum winding coating process, bias voltage fluctuations caused by certain uncertain factors can cause the bias voltage to increase or decrease abnormally, which can cause instability in the production process and affect the stability and consistency of the product. The present invention sets an auxiliary electric field with a gradually varying intensity to effectively assist the flexible film in separating from the roller surface, thus overcoming the above problems. At the same time, by performing online feedback control on the bias voltage and auxiliary electric field of each roller, the position where the flexible film is separated from the coating roller can be adjusted online. This multi-faceted technical effect not only enables the flexible film to obtain an appropriate, required, and stable cooling effect, but also ensures that the film quality on the flexible film is not easily damaged. More importantly, this combined effect enables the winding vacuum coating production process to be continuously and stably implemented without being affected by process fluctuations such as bias voltage fluctuations caused by certain uncertain factors, thereby obtaining a highly consistent and high-quality flexible composite current collector film product.

[0026] The conductive film layers formed on the front and back surfaces of the flexible film are each composed of one selected from the group consisting of copper, aluminum, silver, nickel, molybdenum, titanium, niobium, iron, zinc, stainless steel, graphene, carbon nanotubes, Ketjen black, acetylene black, graphite powder, and carbon fiber. In a preferred embodiment, the conductive film layers are composed of copper and / or aluminum. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the roll-to-roll vacuum coating equipment of the present invention.

[0028] Figure 2 Schematic diagram of the principle of the auxiliary electric field generating device in the present invention.

[0029] The accompanying drawings are only used to schematically illustrate the technical solutions of the present invention, and the proportions of the various parts in the accompanying drawings do not constitute a proportional limitation to the present invention.

[0030] Implementation Method

[0031] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0032] The terms “first,” “second,” “front,” and “back” in the description and claims of the present invention are used to distinguish similar objects but are not necessarily used to describe a specific order.

[0033] Figure 1 FIG. 1 is a schematic structural diagram of the roll-to-roll vacuum coating equipment of the present invention. Figure 1As shown, the roll-to-roll vacuum coating equipment includes an unwinding chamber 10, a winding chamber 20, a first magnetron coating chamber 30, a first evaporation chamber 40, a second magnetron coating chamber 50, a second evaporation chamber 60, a bias generator, and a control center. Dividers are installed between the chambers, and adjacent chambers are connected by slits, allowing the flexible film 70 to pass through the slits between the chambers. The unwinding chamber 10 is equipped with an unwinding roller 101, and the winding chamber 20 is equipped with a winding roller 201. The first magnetron coating chamber 30 is equipped with a front adjustment roller 301, a coating roller 302, and a rear adjustment roller 303. The second magnetron coating chamber 50 is equipped with a front adjustment roller 501, a coating roller 502, and a rear adjustment roller 503. The first evaporation chamber 40 is sequentially arranged with a front adjustment roller 401, a coating roller 402, and a rear adjustment roller 403, as well as a front adjustment roller 404, a coating roller 405, and a rear adjustment roller 406. The second evaporation chamber 60 is sequentially arranged with a front adjustment roller 601, a coating roller 602, and a rear adjustment roller 603, as well as a front adjustment roller 604, a coating roller 605, and a rear adjustment roller 606. In the first and second magnetron coating chambers 30 and 50, multiple magnetron targets 304 and 504 are respectively positioned opposite the coating rollers 302 and 502. The magnetron sputtering coating performed in the first and second magnetron coating chambers 30 and 50 is multi-target magnetron sputtering. Through magnetron sputtering, the magnetron targets deposit a dense base film layer on the flexible film 70 that is wound around the coating rollers. In the first and second evaporation chambers 40 and 60, evaporation sources 407, 408, 607, and 608 are respectively disposed below the coating rollers 402, 405, 602, and 605. The flexible film 70 from the unwinding roller 101 enters the first magnetron coating chamber 30 and passes sequentially through the front regulating roller 301, the coating roller 302, and the rear regulating roller 303. While passing through the coating roller 302, a dense base film layer is formed on the front surface of the flexible film 70 via magnetron sputtering. The flexible film 70 then enters the first evaporation chamber 40 and passes sequentially through the front regulating roller 401, the coating roller 402, the rear regulating roller 403, the front regulating roller 404, the coating roller 405, and the rear regulating roller 406. While passing through the coating rollers 402 and 405, a growth film layer is formed on the base film layer on the front surface of the flexible film 70 via evaporation coating, thereby forming a conductive film layer on the front surface of the flexible film 70. The flexible film 70 then passes through the second magnetron coating chamber 50, sequentially passing through a front adjusting roller 501, a coating roller 502, and a rear adjusting roller 503. Magnetron sputtering is then used to deposit a dense base film layer on the back surface of the flexible film 70. The flexible film 70 then passes through the second evaporation chamber 60, sequentially passing through a front adjusting roller 601, a coating roller 602, a rear adjusting roller 603, a front adjusting roller 604, a coating roller 605, and a rear adjusting roller 606. While passing through coating rollers 602 and 605, a growth film layer is deposited on the base film layer on the back surface of the flexible film 70 through evaporation deposition, thereby forming a conductive film layer on the back surface of the flexible film 70.Finally, the flexible film 70 with the conductive film layer coated on both the front and back sides is rolled up by the winding roller 201 .

[0034] Multiple coating rollers and evaporation sources within the deposition chamber enable the production of thicker films within a single vacuum coating cycle, while maintaining normal or even faster film speeds. The evaporation sources deposit a growth layer on top of the base film layer of the flexible film through evaporation. The base and growth layers combine to form the conductive film layer. Coolant flows through each coating roller to cool the flexible film during magnetron sputtering and evaporation coating.

[0035] A bias generator applies a bias to each coating roller and the bias adjustment roller. This bias ensures that the flexible film adheres tightly to the coating roller surface as it winds around it, achieving a better cooling effect. In a preferred embodiment, the rear adjustment rollers 303 and 503 are biased and serve as bias adjustment rollers. Sensors are located downstream of the coating rollers to monitor the contact between the flexible film and the coating rollers online and transmit signals reflecting this contact to the control center.

[0036] The bias polarity of each coating roller is the same. The bias polarity of the coating rollers 302 and 502 in the first and second magnetron coating chambers 30 and 50 is the same as that of the coating rollers 402, 405, 602, and 605 in the first and second evaporation chambers 40 and 60, resulting in charges of the same polarity distributed on the surfaces of each coating roller. The bias polarity of the bias adjustment roller is opposite to that of the bias of each coating roller. When the flexible film 70 passes over the bias adjustment roller, the bias applied to the bias adjustment roller causes the conductive film layer on the flexible film 70 to have a charge of opposite polarity to that distributed on the coating roller surfaces. Due to the mutual attraction between the two charges of opposite polarity, the flexible film 70 is attracted to the coating rollers as it passes over them, tightly adhering to the coating roller surfaces and achieving improved cooling during magnetron sputtering or evaporation coating.

[0037] In the first magnetron coating chamber 30 and the first evaporation chamber 40, a base film layer and a growth film layer are deposited on the front surface of the flexible film 70, respectively. In the second magnetron coating chamber 50 and the second evaporation chamber 60, a base film layer and a growth film layer are deposited on the back surface of the flexible film 70, respectively. Each chamber is equipped with guide rollers; the flexible film 70 is turned over when it passes over the guide rollers 411 in the first evaporation chamber 40 and the guide rollers 506 in the second magnetron coating chamber 50.

[0038] The thickness of the conductive film layer is 0.3-2 μm, wherein the thickness of the base film layer is 30-200 nm.

[0039] Auxiliary electric field generating devices 305, 409, 410, 505, 609, and 610 are located on opposite sides of each coating roller, downstream of the film path. When the flexible film 70 reaches this downstream region and needs to be removed from the coating roller surface, the auxiliary electric field generated by the auxiliary electric field generating devices assists in removing the flexible film from the roller. The polarity of the auxiliary electric field is the same as the bias voltage of the coating roller.

[0040] Take the auxiliary electric field generating device 409 on the opposite side of the coating roller 402 as an example. Figure 2 As shown, the auxiliary electric field generating device 409 includes an electric field shielding shell 4091 and multiple electric field generating units 4092 arranged in a matrix. The electric field shielding shell 4091 limits the area of ​​action of the auxiliary electric field to the downstream region of each coating roller where the flexible film 70 needs to separate from the coating roller surface, preventing the auxiliary electric field from affecting other areas where the flexible film needs to be closely attached to the coating roller. The auxiliary electric field is a gradient electric field, with the electric field intensity gradually increasing along the direction of the flexible film 70. The auxiliary electric field repel[s] charges of the same polarity on the coating roller, making the charge density on the portion of the coating roller opposite the auxiliary electric field generating device more sparse, thereby weakening the adsorption of the flexible film 70 to this portion. Under this effect, when the flexible film 70 reaches this downstream region and needs to separate from the coating roller, the adsorption between the flexible film and the coating roller is weakened, the degree of adhesion is reduced, and the flexible film 70 is more easily separated from the roller surface. The auxiliary electric field strength is lowest at the starting point of the downstream region. As it extends from the starting point toward the downstream region, the corresponding auxiliary electric field strength increases, and the repulsive effect on like-polarity charges on the coating roller also becomes stronger. Consequently, the charge distribution density at the corresponding portion of the region becomes increasingly sparse, and the attraction of the flexible film 70 to this portion of the region also becomes increasingly weaker. Under the guidance of the rear adjustment roller 403, the attraction of the coating roller to the flexible film 70 is weakest at the pre-designed separation point where the flexible film 70 separates from the coating roller, and the flexible film 70 separates from the coating roller 402 at this point.

[0041] The control center independently controls each electric field generating unit and provides online feedback control over the auxiliary electric field's electric field strength and distribution based on sensor signals. When the sensor transmits the detected sensor signal to the control center, the control center determines whether the degree of contact between the flexible film and the coating roller is too high or too low based on the received sensor signal. It then issues control instructions to each electric field generating unit, adjusting the electric field strength generated by certain units, increasing or decreasing the auxiliary electric field's strength, and changing the electric field distribution. This allows the auxiliary electric field to adapt to the contact situation, effectively assisting the flexible film in detaching from the roller surface.

[0042] The control center can also perform online feedback control of the auxiliary electric field based on the cooling effect of the flexible film on the coating roller. By adjusting the electric field strength and distribution of the auxiliary electric field, the position at which the flexible film separates from the coating roller can be adjusted online. If the control center determines that the flexible film is insufficiently cooled, the control center issues a control instruction to the auxiliary electric field generating device to reduce the electric field strength and change the electric field distribution, so that the position at which the flexible film separates from the coating roller is delayed within an appropriate range compared to the original separation position, thereby enhancing the cooling effect of the flexible film. If the control center determines that the flexible film is excessively cooled, the control center issues a control instruction to the auxiliary electric field generating device to increase the electric field strength and change the electric field distribution, so that the position at which the flexible film separates from the coating roller is advanced within an appropriate range compared to the original separation position, thereby weakening the cooling effect of the flexible film.

[0043] The coating rollers 302 and 502 in the first magnetron coating chamber 30 and the second magnetron coating chamber 50, the coating rollers 402, 405, 602 and 605 in the first evaporation chamber 40 and the second evaporation chamber 60, and the bias adjustment roller are individually feedback-controlled online by the control center based on the sensor signal.

[0044] When the control center determines that the cooling effect of the flexible film needs to be increased or decreased based on the received sensor signal, the control center sends a control instruction to the bias generating device to increase or decrease the bias of a coating roller and a bias adjustment roller close to the coating roller, and adjusts the fit between the flexible film and the surface of the coating roller online, so that the flexible film can obtain the required and stable cooling effect.

[0045] By carrying out multi-target magnetic sputtering coating in the first magnetron coating chamber and the second magnetron coating chamber, and arranging multiple evaporation modules including coating rollers and evaporation sources in the first evaporation chamber and the second evaporation chamber, and at the same time using online controllable bias to make the flexible film and the coating roller fit more closely, the flexible film obtains a better and more stable cooling effect, and overcomes the problems of the flexible film being easily deformed or even damaged by heat when using higher magnetron coating power and evaporation coating power. It is achieved that a thicker film layer can be prepared within one vacuum coating working cycle without reducing the film travel speed of the flexible film.

[0046] The coating roller 502 in the second magnetron coating chamber 50 and the coating rollers 602 and 605 in the second evaporation chamber 60 are further coated with heat-conductive, electrically insulating layers 507, 611, and 612, respectively. These insulating layers are composed of one of aluminum oxide, aluminum nitride, silicon nitride, silicon oxide, zirconium oxide, and resin. These insulating layers prevent charges on the front surface of the flexible film 70 from neutralizing charges on the coating rollers vacuum coating the back surface, thus affecting the adhesion between the flexible film 70 and the coating rollers during vacuum coating of the front surface.

[0047] An auxiliary electric field with gradually varying intensity is set to effectively assist the flexible film in detaching from the roller surface, overcoming the problem that the film layer is easily damaged when the flexible film is separated from the coating roller due to the large bias voltage. At the same time, through online feedback control of the bias voltage and auxiliary electric field of each roller, the production process of preparing a thicker conductive film layer by winding vacuum coating can be maintained continuously and stably without being affected by process fluctuations such as bias fluctuations caused by certain uncertain factors, thereby obtaining a highly consistent and high-quality flexible composite current collector film product.

[0048] The conductive film layers formed on the front and back surfaces of the flexible film are each composed of one selected from the group consisting of copper, aluminum, silver, nickel, molybdenum, titanium, niobium, iron, zinc, stainless steel, graphene, carbon nanotubes, Ketjen black, acetylene black, graphite powder, and carbon fiber. In a preferred embodiment, the conductive film layers are composed of copper or aluminum.

Claims

1. A roll-to-roll vacuum coating device, characterized in that: It includes an unwinding chamber, a winding chamber, a first magnetron coating chamber, a first evaporation chamber, a second magnetron coating chamber, a second evaporation chamber, a bias generating device and a control center; two adjacent chambers are connected by a slit, so that the flexible film can pass through the slit between the chambers; the first magnetron coating chamber, the second magnetron coating chamber, the first evaporation chamber and the second evaporation chamber are sequentially arranged with a front adjustment roller, a coating roller and a rear adjustment roller; in the first magnetron coating chamber and the second magnetron coating chamber, a magnetron target is arranged on the opposite side of the coating roller, and the magnetron target deposits a dense basic film layer on the flexible film wound around the coating roller by magnetron sputtering coating; in the first evaporation chamber and the second evaporation chamber, more than one evaporation source is arranged under the coating roller, and the evaporation source deposits a growth film layer on the basic film layer of the flexible film by evaporation coating; the basic film layer and the growth film layer are combined to form a conductive film layer; Cooling liquid flows through the coating rollers to cool the flexible film during magnetron sputtering coating and evaporation coating; a bias generating device causes each coating roller to have a bias, and causes at least one of the front adjusting rollers and the rear adjusting rollers other than the front adjusting rollers in the first magnetron coating chamber and the second magnetron coating chamber to have a bias as a bias adjusting roller, and the bias causes the flexible film to fit tightly with the surface of the coating roller when it passes around the coating roller, so as to obtain a better cooling effect; a sensor is arranged downstream of the coating roller for online detection of the fitting condition between the flexible film and the coating roller, and transmits a sensor signal reflecting the fitting condition to a control center; an auxiliary electric field generating device is arranged on the opposite side of the downstream side of each coating roller, and when the flexible film reaches the downstream side area and needs to leave the surface of the coating roller, the auxiliary electric field generated by the auxiliary electric field generating device plays an auxiliary role in removing the roller.

2. The roll-to-roll vacuum coating equipment according to claim 1, characterized in that: In the first magnetron coating chamber and the first evaporation chamber, a base film layer and a growth film layer are respectively deposited on the front side of the flexible film; in the second magnetron coating chamber and the second evaporation chamber, a base film layer and a growth film layer are respectively deposited on the reverse side of the flexible film; guide rollers are arranged in each chamber; the flexible film is turned over when passing through the guide rollers in the first evaporation chamber and the second magnetron coating chamber.

3. The roll-to-roll vacuum coating equipment according to claim 1, characterized in that: The auxiliary electric field generating device includes an electric field shielding shell and multiple electric field generating units arranged in a matrix manner. The control center controls each electric field generating unit individually; the control center performs online feedback control on the electric field strength and distribution of the auxiliary electric field according to the sensor signal.

4. The roll-to-roll vacuum coating equipment according to claim 3, characterized in that: When the sensor transmits the detected sensor signal to the control center, the control center determines whether the degree of fit between the flexible film and the coating roller is too high or too low based on the received sensor signal, and sends control instructions to each electric field generating unit to adjust the electric field strength generated by certain electric field generating units, increase or decrease the electric field strength of the auxiliary electric field, and change the electric field distribution, so that the auxiliary electric field can be adaptively adjusted to the degree of fit, thereby forming an effective auxiliary roller-detaching effect for the flexible film to detach from the roller surface.

5. The roll-to-roll vacuum coating equipment according to claim 1, characterized in that: The bias voltage of each coating roller and bias voltage regulating roller is individually controlled by online feedback from the control center according to the sensor signal.

6. The roll-to-roll vacuum coating equipment according to claim 5, characterized in that: When the control center determines that the cooling effect of the flexible film needs to be improved or reduced based on the received sensor signal, the control center sends a control instruction to the bias generating device to increase or decrease the bias of a coating roller and a bias adjusting roller close to the coating roller, and adjusts the degree of fit between the flexible film and the surface of the coating roller online, so that the flexible film can obtain the required and stable cooling effect.

7. The roll-to-roll vacuum coating equipment according to claim 1, characterized in that: The auxiliary electric field is a gradient electric field, and the gradient trend of the electric field intensity is that it gradually increases along the direction of the flexible film.

8. The roll-to-roll vacuum coating equipment according to claim 1, characterized in that: The bias polarity of the bias regulating roller is opposite to the bias polarity of each coating roller; the polarity of the auxiliary electric field is the same as the bias polarity of the coating roller.

9. The roll-to-roll vacuum coating equipment according to claim 1, characterized in that: In the first magnetron coating chamber and the second magnetron coating chamber, there are multiple magnetron targets arranged on the opposite side of the coating roller; there are more than two coating rollers arranged in the first evaporation chamber and the second evaporation chamber; the thickness of the conductive film layer is 0.3-2μm.

10. The roll-to-roll vacuum coating equipment according to claim 1, characterized in that: The outer surface layer of the coating roller in the second magnetron coating chamber and the second evaporation chamber is also provided with a heat-conductive electrical insulation layer, and the composition of the electrical insulation layer is one of aluminum oxide, aluminum nitride, silicon nitride, silicon oxide, zirconium oxide, and resin.

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