A dry electrode film forming device and method

Abstract

The present application relates to a dry electrode film forming device and method, the dry electrode film forming device comprises: a heating and mixing unit for forming a mixture; an extrusion die unit for extruding the mixture into an initial film sheet in a manner of preset width and thickness, which can adjust the extrusion pressure; a cooling roller group unit for adjusting the tension of the film sheet and controlling the initial film sheet to be cooled to a temperature lower than or equal to a first preset temperature during the process of pulling and stretching the initial film sheet; an area density control unit for performing an area density detection on the initial film sheet and controlling the extrusion die unit to adjust the extrusion pressure according to the result of the area density detection; a preheating unit for heating the initial film sheet to a temperature higher than or equal to a second preset temperature; a calendering unit for heating and rolling the initial film sheet to stretch it into a thin film sheet, which can adjust the rolling pressure; a thickness control unit for performing a thickness detection on the thin film sheet and controlling the calendering unit to adjust the rolling pressure according to the result of the thickness detection.

Description

Technical Field

[0001] The present application relates to the technical field of battery electrode preparation, and in particular to a dry electrode film forming device and method. Background Art

[0002] The dry electrode membrane preparation process includes powder spraying and binder fiberization. Because the powder spraying method is prone to component segregation and unevenness, the binder fiberization method is currently the mainstream. The binder fiberization method is to add active materials and conductive agent powders to a solid binder, and then apply high shear force to fiberize the binder to bond the powders together. The binder is then compacted and thinned by extrusion to form a self-supporting film, and the self-supporting film is then rolled and composited with the current collector to form an electrode. The current electrode membrane production equipment using the binder fiberization method has the following problems: it is difficult to achieve and ensure the uniformity of the thickness of the membrane in the width direction during the extrusion process to form the self-supporting film, and it is difficult to achieve and ensure the consistency of the surface density and thickness of the membrane formed before and after. Summary of the invention

[0003] Based on this, the present application provides a dry electrode film forming device and method, which can facilitate the realization and guarantee of good thickness uniformity of the membrane in the width direction, and can facilitate the realization and guarantee of good consistency in the surface density and thickness of the front and rear membranes.

[0004] The technical solutions adopted in this application are as follows:

[0005] A dry electrode film forming device comprises: a heating and mixing unit, which is used to heat and stir a binder to make it fibrous and mix it with active material powder and conductive agent powder to form a mixture; an extrusion die unit, which is used to extrude the mixture into an initial film sheet in a manner of preset width and thickness; the extrusion die unit is capable of adjusting the extrusion pressure on the mixture; a cooling roller group unit, which is used to traction and stretch the initial film sheet coming out of the extrusion die unit, and adjust the tension of the initial film sheet during the traction and stretching process and control the initial film sheet to be cooled to a temperature lower than or equal to a first preset temperature; a surface density control unit, which is used to traction and stretch the initial film sheet coming out of the cooling roller group unit The surface density of the film is detected, and the extrusion die unit is controlled to adjust the extrusion pressure of the mixture according to the result of the surface density detection; a preheating unit is used to heat the initial film coming out of the surface density control unit to a temperature higher than or equal to a second preset temperature; a calendering unit is used to heat and roll the initial film coming out of the preheating unit to extend the initial film into a thin film; the calendering unit can adjust the rolling pressure on the initial film; a thickness control unit is used to detect the thickness of the thin film coming out of the calendering unit, and control the calendering unit to adjust the rolling pressure on the initial film according to the result of the thickness detection.

[0006] Furthermore, the extrusion die unit includes an extrusion die body, which has a feed port and a discharge port, the feed port is connected to the discharge port of the heating and mixing unit, a constant pressure metering pump is provided on the feed port of the extrusion die body, the discharge port is in the shape of a rectangular slit, and a constant temperature heating device is provided on the extrusion die body.

[0007] Furthermore, the surface density control unit includes a surface density detection device and a surface density controller; the surface density detection device is used to detect the surface density of the initial diaphragm and send the detected surface density value to the surface density controller; the surface density controller receives the surface density value sent by the surface density detection device, and compares the surface density value with the preset surface density value. When the received surface density value is less than the preset surface density value, the surface density controller controls the extrusion die unit to increase the extrusion pressure on the mixture. When the received surface density value is greater than the preset surface density value, the surface density controller controls the extrusion die unit to reduce the extrusion pressure on the mixture.

[0008] Furthermore, the cooling roller group unit includes a casting roller, a shaping roller, a floating roller and a tension roller, and the casting roller, the floating roller and the tension roller are arranged in sequence along the forward direction of the initial film sheet, and the shaping roller is arranged on the feed side of the casting roller, and is used to apply a thrust to the initial film sheet so that the initial film sheet is tightly attached to the casting roller; the casting roller, the floating roller and the tension roller are all provided with temperature control devices to reduce the temperatures of the casting roller, the floating roller and the tension roller in sequence.

[0009] Furthermore, the calendering unit includes at least one pair of roller assemblies, the pair of roller assemblies including an upper pressure roller, a lower pressure roller and a roller gap adjustment mechanism, the upper pressure roller and the lower pressure roller are arranged opposite to each other up and down, and the roller gap adjustment mechanism is used to adjust the roller gap between the upper pressure roller and the lower pressure roller; the upper pressure roller and the lower pressure roller are both heating rollers.

[0010] Furthermore, the thickness control unit includes a thickness detection device and a thickness controller; the thickness detection device is used to detect the thickness of the thin film and send the detected thickness value to the thickness controller; the thickness controller receives the thickness value sent by the thickness detection device, and compares the thickness value with a preset thickness value. When the received thickness value is less than the preset thickness value, the thickness controller controls the calendering unit to increase the rolling pressure on the initial film, and when the received thickness value is greater than the preset thickness value, the thickness controller controls the calendering unit to reduce the rolling pressure on the initial film.

[0011] Furthermore, the heating and mixing unit includes a horizontal heating cylinder and a screw arranged in the horizontal heating cylinder, the screw is connected to a screw driving mechanism, the horizontal heating cylinder is provided with a plurality of discharge ports arranged at intervals along the length of the cylinder, and a discharge port is opened at the end of the horizontal heating cylinder.

[0012] Furthermore, the preheating unit includes an infrared radiation heating device.

[0013] Furthermore, the dry electrode film forming device also includes: a tension control unit, which is used to control the tension of the thin film coming out of the calendering unit; a trimming unit, which is used to trim the thin film coming out of the tension control unit; and a winding unit, which is used to wind the thin film into a roll after trimming by the trimming unit.

[0014] A dry electrode film forming method comprises the following steps:

[0015] The binder is heated and stirred to be fiberized and mixed with the active material powder and the conductive agent powder to form a mixture;

[0016] Extruding the mixture into an initial film in a predetermined width and thickness;

[0017] Drawing and stretching the initial film sheet, adjusting the tension of the initial film sheet during the drawing and stretching process and controlling the initial film sheet to cool down to a temperature lower than or equal to a first preset temperature;

[0018] Performing a surface density test on the initial film sheet having a temperature lower than or equal to a first preset temperature, and adjusting an extrusion pressure when extruding the mixture into the initial film sheet according to a result of the surface density test;

[0019] Heating the initial membrane having a temperature lower than or equal to a first preset temperature to a temperature higher than or equal to a second preset temperature;

[0020] Heating and rolling the initial film sheet having a temperature higher than or equal to a second preset temperature so as to extend the initial film sheet into a thin film sheet;

[0021] The thickness of the thin film is detected, and the rolling pressure when the initial film is heated and rolled is adjusted according to the result of the thickness detection.

[0022] The dry electrode membrane forming device and method of the present application first heats and stirs the binder to make it fiberized and mixes it with the active material powder and the conductive agent powder to form a mixture, and then successively passes through extrusion by an extrusion die unit, traction and stretching by a cooling roller group unit, and extrusion and extension by a calendering unit to finally obtain a thin membrane, i.e., a self-supporting membrane. The extrusion die unit extrude the mixture in a manner of preset width and thickness when extruding the mixture, so that the thickness of the initial membrane formed by extrusion in the width direction is basically the same. On this basis, the initial membrane is subsequently subjected to traction, stretching, and extrusion and extension, which can facilitate the realization and guarantee of a good thickness uniformity of the final formed membrane in the width direction. After the mixture is extruded into the initial membrane, the initial membrane is cooled by the cooling roller group unit. , detect the surface density of the initial diaphragm, and adjust the extrusion pressure of the mixture on the extrusion die unit according to the detection result. The density of the material on the extruded initial diaphragm can be changed by adjusting the extrusion pressure. If the surface density changes, the extrusion pressure can be adjusted to return to the original surface density, so that it is easy to achieve and ensure that the surface density of the front and rear diaphragms has good consistency; after the calendering unit extrude the initial diaphragm and stretch it into a thin diaphragm, detect the thickness of the thin diaphragm, and adjust the rolling pressure of the initial diaphragm on the basis of the detection result. The thickness of the diaphragm after rolling can be changed by adjusting the rolling pressure. If the thickness changes, the rolling pressure can be adjusted to return to the original thickness, so that it is easy to achieve and ensure that the thickness of the front and rear diaphragms has good consistency. Therefore, the dry electrode membrane forming device and method of the present application can facilitate the realization and guarantee that the diaphragm has good thickness uniformity in the width direction, and can facilitate the realization and guarantee that the surface density and thickness of the front and rear diaphragms have good consistency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 This is a schematic structural diagram of a dry electrode film forming device according to an embodiment of the present application;

[0025] Figure 2 for Figure 1 A schematic diagram of the structure of the heating and mixing unit, the extrusion die unit, the cooling roller unit and the surface density control unit;

[0026] Figure 3 This is a schematic diagram of the structure of the extrusion die unit of an embodiment of the present application.

[0027] Description of reference numerals:

[0028] 10. Heating and mixing unit; 11. Horizontal heating cylinder; 12. Screw; 13. Screw driving mechanism; 14. Discharging port; 20. Extrusion die unit; 21. Die body; 22. Constant pressure metering pump; 23. Filter; 241. Heating tube; 30. Cooling roller group unit; 31. Casting roller; 32. Shaping roller; 33. Floating roller; 34. Tension roller; 40. Surface density control unit; 41. Surface density detection device; 42. Surface density controller; 50. Preheating unit; 60. Calendering unit; 70. Thickness control unit; 71. Thickness detection device; 72. Thickness controller; 80. Tension control unit; 90. Trimming unit; 100. Winding unit. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below with reference to the accompanying drawings. The present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0030] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0031] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0032] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like 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 an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0033] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0034] refer to Figure 1 The present application provides a dry electrode film forming device, including a heating and mixing unit 10, an extrusion die unit 20, a cooling roller group unit 30, a surface density control unit 40, a preheating unit 50, a calendering unit 60 and a thickness control unit 70.

[0035] The heating and mixing unit 10 is used to heat and stir the binder to make it fiberized and mix it with the active material powder and the conductive agent powder to form a mixture. The extrusion die unit 20 is used to extrude the mixture into an initial film in a preset width and thickness, and the extrusion die unit 20 can adjust the extrusion pressure of the mixture. The cooling roller group unit 30 is used to traction and stretch the initial film coming out of the extrusion die unit 20, and adjust the tension of the initial film during the traction and stretching process and control the initial film to cool down to a temperature lower than or equal to a first preset temperature. The surface density control unit 40 is used to perform surface density detection on the initial film coming out of the cooling roller group unit 30, and control the extrusion die unit 20 to adjust the extrusion pressure of the mixture according to the result of the surface density detection. The preheating unit 50 is used to heat the initial film coming out of the surface density control unit 40 to a temperature higher than or equal to a second preset temperature. The calendering unit 60 is used to heat and roll the initial film sheet coming out of the preheating unit 50 so as to extend the initial film sheet into a thin film sheet. The calendering unit 60 can adjust the rolling pressure on the initial film sheet. The thickness control unit 70 is used to detect the thickness of the thin film sheet coming out of the calendering unit 60, and control the calendering unit 60 to adjust the rolling pressure on the initial film sheet according to the result of the thickness detection.

[0036] The dry electrode membrane forming device of the present application first heats and stirs the binder to make it fiberized and mixes it with the active material powder and the conductive agent powder to form a mixture, and then successively passes through the extrusion die unit 20 for extrusion, the traction and stretching by the cooling roller group unit 30 and the extrusion and extension by the calendering unit 60 to finally obtain a thin membrane, i.e., a self-supporting membrane, wherein the extrusion die unit 20 extrude the mixture in a manner of preset width and thickness, so the thickness of the initial membrane formed by extrusion is basically the same in the width direction, and on this basis, the initial membrane is subsequently subjected to traction, stretching and extrusion and extension, which can facilitate the realization and guarantee of the final formed membrane having good thickness uniformity in the width direction; after the mixture is extruded into the initial membrane, the initial membrane is cooled by the cooling roller group unit 30 After that, the surface density of the initial diaphragm is detected, and the extrusion die unit 20 is adjusted to the extrusion pressure of the mixture according to the detection result. The compactness of the material on the extruded initial diaphragm can be changed by adjusting the extrusion pressure. If the surface density changes, the extrusion pressure can be adjusted to return to the original surface density, so that it is easy to achieve and ensure that the surface density of the front and rear diaphragms has a good consistency; after the calendering unit 60 extrude the initial diaphragm and stretch it into a thin diaphragm, the thickness of the thin diaphragm is detected, and the calendering unit 60 is adjusted to the rolling pressure of the initial diaphragm according to the detection result. The thickness of the diaphragm after rolling can be changed by adjusting the rolling pressure. If the thickness changes, the rolling pressure can be adjusted to return to the original thickness, so that it is easy to achieve and ensure that the thickness of the front and rear diaphragms has a good consistency. Therefore, the dry electrode membrane forming device of the present application can facilitate the realization and guarantee that the diaphragm has a good thickness uniformity in the width direction, and can facilitate the realization and guarantee that the surface density and thickness of the front and rear diaphragms have a good consistency.

[0037] In this embodiment, the heating and mixing unit 10 includes a horizontal heating cylinder 11 and a screw 12 arranged in the horizontal heating cylinder 11, the screw 12 is connected to a screw 12 driving mechanism, and a plurality of discharge ports 14 are arranged at intervals along the length of the cylinder on the horizontal heating cylinder 11, and a discharge port is opened at the end of the horizontal heating cylinder 11.

[0038] The horizontal heating cylinder 11 is provided with multiple discharge ports 14. According to the difference in powder composition provided by each manufacturer and the order in which the components are added, the active agent, the conductive agent and the binder can be selected to enter the horizontal heating cylinder 11 from any discharge port 14. In the horizontal heating cylinder 11, the binder is heated, and under the stirring of the screw 12, the binder is subjected to a strong shear force and fiberized, and is mixed with the active material powder and the conductive agent powder during stirring to form a mixture. The rotation of the screw 12 will also extrude and transport the mixture to the discharge port at the end of the horizontal heating cylinder 11. Under the action of heating and the screw 12, the binder is fully fiberized, with high bonding strength and good toughness. After the initial film is formed, it is not easy to break the film, which is conducive to improving the calendering quality of the subsequent initial film.

[0039] In this embodiment, if Figure 3 As shown, the extrusion die unit 20 includes an extrusion die body 21, and the extrusion die body 21 has a feed port and a discharge port. The feed port is connected to the discharge port of the horizontal heating cylinder 11 of the heating and mixing unit 10. A filter 23 and a constant pressure metering pump 22 are provided on the feed port of the extrusion die body 21. The discharge port is in the shape of a rectangular slit, and a constant temperature heating device is provided on the extrusion die body 21.

[0040] The mixture is fed into the extrusion die body 21 via a constant pressure metering pump, and is heated by a constant temperature heating device in the extrusion die body 21, so that the mixture in the extrusion die body 21 is kept at a constant temperature and pressure state, ensuring that it can be smoothly extruded from the rectangular slit-shaped discharge port. The constant temperature heating device includes a heating tube 241, a thermocouple, and a temperature control module, which are used to heat the extrusion die body 21 and keep the temperature of the extrusion die body 21 within a suitable range, and the extrusion die body 21 transfers heat to the mixture. The mixture generates a certain friction force due to the pressure inside the extrusion die body 21, which is conducive to further fiberizing the binder and making it easier to form a film.

[0041] The discharge port is in the shape of a rectangular slit, with a preset width and thickness, so that the mixture can be extruded into an initial film in a preset width and thickness, so that the initial film has good thickness uniformity in the width direction, and the thickness uniformity of the final film product in the width direction is mainly achieved thereby, and the subsequent calendering of the initial film plays a role in correcting a small amount of deviation. The discharge port can also be provided with a discharge adjustment mechanism for adjusting the opening of the rectangular slit, so as to adjust according to the needs of different products.

[0042] In this embodiment, the cooling roller group unit 30 includes a casting roller 31, a shaping roller 32, a floating roller 33 and a tension roller 34. The casting roller 31, the floating roller 33 and the tension roller 34 are arranged in sequence along the forward direction of the initial film sheet. The shaping roller 32 is arranged on the feed side of the casting roller 31, and is used to apply a thrust to the initial film sheet so that the initial film sheet is tightly attached to the casting roller 31; the casting roller 31, the floating roller 33 and the tension roller 34 are all provided with temperature control devices, and the heating temperatures of the casting roller 31, the floating roller 33 and the tension roller 34 are reduced in sequence.

[0043] The initial film sheet coming out of the extrusion die unit 20 is firstly wound on the casting roller 31. The shaping roller 32 is on the feeding side of the casting roller 31, and applies a thrust to the initial film sheet so that the initial film sheet is closely attached to the casting roller 31, so as to discharge the air between the initial film sheet and the casting roller 31, and reduce the vibration of the initial film sheet at high speed, thereby ensuring the quality of the subsequent product film sheet. The floating roller 33 and the tension roller 34 can control the tension of the initial film sheet to prevent the initial film sheet from breaking or falling off the roller.

[0044] Temperature control devices are provided on the casting roller 31, the floating roller 33 and the tension roller 34 respectively, and the temperature control devices keep the roller surface temperature within a suitable range, and circulating cooling water can be used for temperature control. The temperatures of the casting roller 31, the floating roller 33 and the tension roller 34 are successively reduced and are all lower than the temperature of the initial film coming out of the extrusion die head unit 20, in order to accurately control the cooling speed of the initial film so that the initial film reaches a predetermined temperature at a predetermined time of ejection, so as to facilitate the detection of the surface density, and also prevent the initial film from cracking due to excessive cooling.

[0045] As the temperature decreases, the film tension gradually increases. The initial film is cooled down to a temperature lower than or equal to a first preset temperature by the cooling roller group unit 30, and the first preset temperature is preferably 40°C.

[0046] The cooling roller group unit 30 can be moved horizontally and raised and lowered as a whole to adjust the relative position with the extrusion die unit 20. The floating roller 33 can also be raised and lowered separately to adjust the tension of the initial film.

[0047] In this embodiment, the surface density control unit 40 includes a surface density detection device 41 and a surface density controller 42. The surface density detection device 41 is used to detect the surface density of the initial membrane and send the detected surface density value to the surface density controller 42. The surface density controller 42 receives the surface density value sent by the surface density detection device 41, and compares the surface density value with the preset surface density value. When the received surface density value is less than the preset surface density value, the surface density controller 42 controls the extrusion die unit 20 to increase the extrusion pressure on the mixture. When the received surface density value is greater than the preset surface density value, the surface density controller 42 controls the extrusion die unit 20 to reduce the extrusion pressure on the mixture.

[0048] According to the structure of the extrusion die unit 20, the extrusion pressure of the mixture is achieved by adjusting the delivery volume of the constant pressure metering pump 22. Specifically, the surface density controller 42 compares the surface density value with the preset surface density value. When the received surface density value is less than the preset surface density value, the surface density controller 42 controls the constant pressure metering pump 22 to increase the delivery volume. When the received surface density value is greater than the preset surface density value, the surface density controller 42 controls the constant pressure metering pump 22 to reduce the delivery volume.

[0049] The surface density detection device 41 can be an X-ray or β-ray surface density measuring instrument. When the X-ray / β-ray penetrates the membrane, the intensity attenuation occurs. The attenuation conforms to the exponential law and is related to the surface density of the membrane. The surface density of the membrane is measured according to the attenuation of the detection ray. In this way, non-contact online measurement can be achieved.

[0050] In this embodiment, the preheating unit 50 includes an infrared radiation heating device. The infrared radiation heating device is in the form of a microcrystalline heating plate, an infrared heating tube, etc. Preheating the film before calendering can reduce the pressure resistance of the film adhesive, improve the physical properties of the film during calendering and thinning, and increase the compaction density of the film.

[0051] In this embodiment, the calendering unit 60 includes at least one pair of roller assemblies, and the pair of roller assemblies include an upper pressure roller, a lower pressure roller and a roller gap adjustment mechanism. The upper pressure roller and the lower pressure roller are arranged opposite to each other up and down, and the roller gap adjustment mechanism is used to adjust the roller gap between the upper pressure roller and the lower pressure roller; the upper pressure roller and the lower pressure roller are both heating rollers.

[0052] The upper pressing roller and the lower pressing roller are both heating rollers, and can be heated by electromagnetic heating or mold temperature heat transfer oil heating. The preheating unit 50 and the upper pressing roller and the lower pressing roller fully heat the film entering the calendering zone, reduce the pressure resistance of the film adhesive, promote the fiberization of the film adhesive, thereby improving the strength, toughness and compacted density of the film and reducing the calendering force.

[0053] According to the process requirements, the calendering unit 60 can be provided with a plurality of roller assemblies to perform multi-stage calendering on the diaphragm. The multi-stage calendering makes the diaphragm thinner in steps, which is beneficial to improve the compaction density of the diaphragm and then improve the energy density of the battery.

[0054] In this embodiment, the thickness control unit 70 includes a thickness detection device 71 and a thickness controller 72. The thickness detection device 71 is used to detect the thickness of the thin film and send the detected thickness value to the thickness controller 72. The thickness controller 72 receives the thickness value sent by the thickness detection device 71 and compares the thickness value with a preset thickness value. When the received thickness value is less than the preset thickness value, the thickness controller 72 controls the calendering unit 60 to increase the rolling pressure on the initial film. When the received thickness value is greater than the preset thickness value, the thickness controller 72 controls the calendering unit 60 to reduce the rolling pressure on the initial film.

[0055] According to the structure of the calendering unit 60, the rolling pressure of the initial membrane is achieved by adjusting the roller gap between the upper pressing roller and the lower pressing roller. Therefore, specifically, the thickness controller 72 compares the thickness value with the preset thickness value. When the received thickness value is less than the preset thickness value, the thickness controller 72 controls the roller gap adjustment mechanism to increase the roller gap between the upper pressing roller and the lower pressing roller. When the received thickness value is greater than the preset thickness value, the thickness controller 72 controls the roller gap adjustment mechanism to reduce the roller gap between the upper pressing roller and the lower pressing roller.

[0056] The thickness detection of the diaphragm is performed when the temperature of the diaphragm is lower than or equal to 45°C. The thickness detection device 71 includes an upper laser displacement meter and a lower laser displacement meter. The upper laser displacement meter is used to measure the distance between the upper surface of the diaphragm and the lower laser displacement meter is used to measure the distance between the lower surface of the diaphragm. The difference between the two distances after compensation is the thickness of the diaphragm.

[0057] Furthermore, a thickness detection device 71 is provided on the left and right sides of the diaphragm, respectively, and the pair of roller assemblies is provided with two roller gap adjustment mechanisms to adjust the roller gaps on the left and right sides respectively. The thickness controller 72 compares the thickness detection values ​​of the left and right thickness detection devices 71 with the preset thickness values, and controls the left roller gap adjustment mechanism to adjust the left roller gap when the thickness detection value on the left is different from the preset thickness value, and controls the right roller gap adjustment mechanism to adjust the right roller gap when the thickness detection value on the right is different from the preset thickness value. In this way, the uniformity of the thickness of the diaphragm in the width direction can be further ensured.

[0058] In this embodiment, the dry electrode film forming device further includes a tension control unit 80, a trimming unit 90 and a winding unit 100. The tension control unit 80 is used to control the tension of the thin film sheet coming out of the calendering unit 60. The trimming unit 90 is used to trim the thin film sheet coming out of the tension control unit 80. The winding unit 100 is used to wind the thin film sheet trimmed by the trimming unit 90 into a roll.

[0059] The tension control unit 80 includes two guide rollers and a floating roller disposed between the two guide rollers. The floating roller can be moved up and down by a servo motor driving a ball screw to achieve tension control.

[0060] In this embodiment, the thickness detection device 71 is disposed between the tension control unit 80 and the trimming unit 90 .

[0061] The present application also provides a dry electrode film forming method, comprising the following steps:

[0062] The binder is heated and stirred to be fiberized and mixed with the active material powder and the conductive agent powder to form a mixture;

[0063] Extruding the mixture into an initial film in a predetermined width and thickness;

[0064] Drawing and stretching the initial film sheet, adjusting the tension of the initial film sheet during the drawing and stretching process and controlling the initial film sheet to cool down to a temperature lower than or equal to a first preset temperature;

[0065] Performing a surface density test on the initial film sheet having a temperature lower than or equal to a first preset temperature, and adjusting an extrusion pressure when extruding the mixture into the initial film sheet according to a result of the surface density test;

[0066] Heating the initial membrane having a temperature lower than or equal to a first preset temperature to a temperature higher than or equal to a second preset temperature;

[0067] Heating and rolling the initial film sheet having a temperature higher than or equal to a second preset temperature so as to extend the initial film sheet into a thin film sheet;

[0068] The thickness of the thin film is detected, and the rolling pressure when the initial film is heated and rolled is adjusted according to the result of the thickness detection.

[0069] The dry electrode film forming method of the present application can facilitate the realization and guarantee of good thickness uniformity of the membrane in the width direction, and can facilitate the realization and guarantee of good consistency in the surface density and thickness of the front and rear membranes.

[0070] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0071] The above-described embodiments only express several implementation methods of the present application and should not be construed as limiting the scope of the patent application. It should be noted that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be subject to the attached claims.

Claims

1. A dry electrode film forming device, characterized in that: include: A heating and mixing unit, used for heating and stirring the binder to make it fiberized and mixing it with the active material powder and the conductive agent powder to form a mixture; An extrusion die unit, used to extrude the mixture into an initial film in a manner of preset width and thickness; the extrusion die unit is capable of adjusting the extrusion pressure on the mixture; A cooling roller group unit, used for pulling and stretching the initial film sheet coming out of the extrusion die head unit, adjusting the tension of the initial film sheet during the pulling and stretching process, and controlling the initial film sheet to cool down to a temperature lower than or equal to a first preset temperature; A surface density control unit, used for detecting the surface density of the initial film sheet coming out of the cooling roller group unit, and controlling the extrusion die head unit to adjust the extrusion pressure of the mixture according to the result of the surface density detection; A preheating unit, used for heating the initial film coming out of the surface density control unit to a temperature higher than or equal to a second preset temperature; A calendering unit, used for heating and rolling the initial film sheet coming out of the preheating unit, so as to stretch the initial film sheet into a thin film sheet; the calendering unit can adjust the rolling pressure on the initial film sheet; The thickness control unit is used to detect the thickness of the thin film coming out of the calendering unit, and control the calendering unit to adjust the rolling pressure on the initial film according to the result of the thickness detection.

2. The dry electrode film forming device according to claim 1, characterized in that: The extrusion die unit comprises an extrusion die body, which has a feed port and a discharge port. The feed port is connected to the discharge port of the heating and mixing unit. A constant pressure metering pump is arranged on the feed port of the extrusion die body. The discharge port is in the shape of a rectangular slit. A constant temperature heating device is arranged on the extrusion die body.

3. The dry electrode film forming device according to claim 1, characterized in that: The surface density control unit includes a surface density detection device and a surface density controller; the surface density detection device is used to detect the surface density of the initial diaphragm and send the detected surface density value to the surface density controller; the surface density controller receives the surface density value sent by the surface density detection device, and compares the surface density value with the preset surface density value. When the received surface density value is less than the preset surface density value, the surface density controller controls the extrusion die unit to increase the extrusion pressure on the mixture. When the received surface density value is greater than the preset surface density value, the surface density controller controls the extrusion die unit to reduce the extrusion pressure on the mixture.

4. The dry electrode film forming device according to claim 1, characterized in that: The cooling roller group unit includes a casting roller, a shaping roller, a floating roller and a tension roller. The casting roller, the floating roller and the tension roller are arranged in sequence along the forward direction of the initial film sheet. The shaping roller is arranged on the feed side of the casting roller, and is used to apply a thrust to the initial film sheet so that the initial film sheet is tightly attached to the casting roller. The casting roller, the floating roller and the tension roller are all provided with temperature control devices to reduce the temperatures of the casting roller, the floating roller and the tension roller in sequence.

5. The dry electrode film forming device according to claim 1, characterized in that: The calendering unit includes at least one pair of roller assemblies, the pair of roller assemblies include an upper pressing roller, a lower pressing roller and a roller gap adjustment mechanism, the upper pressing roller and the lower pressing roller are arranged opposite to each other up and down, and the roller gap adjustment mechanism is used to adjust the roller gap between the upper pressing roller and the lower pressing roller; the upper pressing roller and the lower pressing roller are both heated rollers.

6. The dry electrode film forming device according to claim 1, characterized in that: The thickness control unit includes a thickness detection device and a thickness controller; the thickness detection device is used to detect the thickness of the thin film and send the detected thickness value to the thickness controller; the thickness controller receives the thickness value sent by the thickness detection device, and compares the thickness value with a preset thickness value. When the received thickness value is less than the preset thickness value, the thickness controller controls the calendering unit to increase the rolling pressure on the initial film, and when the received thickness value is greater than the preset thickness value, the thickness controller controls the calendering unit to reduce the rolling pressure on the initial film.

7. The dry electrode film forming device according to claim 1, characterized in that: The heating and mixing unit comprises a horizontal heating cylinder and a screw arranged in the horizontal heating cylinder, wherein the screw is connected to a screw driving mechanism, a plurality of discharge ports are arranged at intervals along the length of the cylinder, and a discharge port is opened at the end of the horizontal heating cylinder.

8. The dry electrode film forming device according to claim 1, characterized in that: The preheating unit includes an infrared radiation heating device.

9. The dry electrode film forming device according to claim 1, characterized in that: The dry electrode film forming device also includes: A tension control unit, used for controlling the tension of the thin film coming out of the calendering unit; A trimming unit, used for trimming the thin film coming out of the tension control unit; The winding unit is used to wind the thin film into a roll after being trimmed by the trimming unit.

10. A dry electrode film forming method, characterized in that: The following steps are involved: The binder is heated and stirred to be fiberized and mixed with the active material powder and the conductive agent powder to form a mixture; Extruding the mixture into an initial film in a predetermined width and thickness; Drawing and stretching the initial film sheet, adjusting the tension of the initial film sheet during the drawing and stretching process and controlling the initial film sheet to cool down to a temperature lower than or equal to a first preset temperature; Performing a surface density test on the initial film sheet having a temperature lower than or equal to a first preset temperature, and adjusting an extrusion pressure when extruding the mixture into the initial film sheet according to a result of the surface density test; Heating the initial membrane having a temperature lower than or equal to a first preset temperature to a temperature higher than or equal to a second preset temperature; Heating and rolling the initial film sheet having a temperature higher than or equal to a second preset temperature so as to extend the initial film sheet into a thin film sheet; The thickness of the thin film is detected, and the rolling pressure when the initial film is heated and rolled is adjusted according to the result of the thickness detection.

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