Roll press apparatus for manufacturing secondary battery

Abstract

The disclosed invention relates to a roll press apparatus for performing hot rolling on an electrode coated with an electrode active material. In one example, a pre-heater is disposed upstream of a rolling unit for performing rolling on an electrode transferred in a roll-to-roll manner, and the pre-heater irradiates an infrared laser along the width direction of the surface of the electrode to heat the electrode with radiant heat.

Description

Roll press device for secondary battery manufacturing

[0001] The present invention relates to a roll press device for performing hot rolling on an electrode for a secondary battery.

[0002] This application claims the benefit of priority from Republic of Korea Patent Application No. 10-2023-0173935, dated December 5, 2023, the entire contents of which are incorporated herein by reference.

[0003] As technological development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing, and accordingly, extensive research is being conducted on secondary batteries that can meet various needs.

[0004] In terms of battery shape, there is a high demand for square secondary batteries and pouch-type secondary batteries that can be applied to products such as mobile phones due to their thin thickness. In terms of materials, there is a high demand for lithium secondary batteries such as lithium-ion batteries and lithium-ion polymer batteries that have advantages such as high energy density, discharge voltage, and output stability.

[0005] A secondary battery like this is manufactured by coating an electrode mixture containing an active material, a conductive material, and a binder on an electrode sheet, and then stacking electrodes manufactured through a rolling process, a drying process, a slitting process, and a notching process with a separator in between, and then housing the electrode assembly in a battery case, injecting an electrolyte, and sealing the electrode assembly.

[0006] Many of the processes performed during the manufacture of these secondary batteries are performed using a roll-to-roll method. That is, an unwinder unwinds the electrode roll, which is wound onto a bobbin, and various processes are performed simultaneously. At the same time, a rewinder rewinds the processed electrode roll, thereby performing processes such as rolling and drying.

[0007] The rolling process uses a roll press device that applies pressure by running an electrode between two rolls. Hot rolling using a roll press device raises the electrode temperature, reducing surface hardness and achieving high rolling density with low rolling force. Current electrode heating methods use electric heating rods to directly heat the rolls, which then conduct heat to the electrode surface.

[0008] However, the conduction heating method has a slow heating response time, residual heat remains even when the power supply to the heating rod is cut off, resulting in a slow cooling rate. Furthermore, the time required for heat conduction to the electrode makes it difficult to increase the speed of the electrode roll. While increasing the roll speed can reduce the tact time, the conduction heating method presents limitations in improving these processes.

[0009] The purpose of the present invention is to provide a roll press device that improves the heating and cooling responsiveness of an electrode surface using radiant heat and does not cause quality problems such as wrinkles in the non-conductive region due to foil expansion by selectively heating an electrode active material.

[0010] However, the technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0011] The present invention relates to a roll press device that performs hot rolling on an electrode coated with an electrode active material, and in one example, a pre-heater is arranged upstream of a rolling unit that performs rolling on an electrode transported in a roll-to-roll manner, and the pre-heater heats the electrode surface by radiating an infrared laser along the width direction thereof.

[0012] In one embodiment of the present invention, the wavelength of the infrared laser irradiated by the pre-heater is characterized in that it has an absorption rate of at least 10% or less for copper or aluminum, which is the material of the electrode, and an absorption rate of at least 70% or more for the electrode active material.

[0013] For example, the wavelength of the infrared laser may be within the range of 1,064±100 nm.

[0014] And, the output of the infrared laser can be controlled to an output such that the temperature of the electrode active material is in the range of 80±5°C.

[0015] In one embodiment, the output of the infrared laser can be controlled to an output per unit time that varies depending on the transport speed of the electrode.

[0016] In addition, the pre-heater can irradiate the infrared laser in a line beam or square beam manner across the transport direction of the electrode transported in a roll-to-roll manner.

[0017] Meanwhile, the present invention provides a hot rolling method for an electrode for a secondary battery, in which an electrode coated with an electrode active material is transported in a roll-to-roll manner, and a pre-heater disposed upstream of a rolling unit that performs rolling on the electrode irradiates an infrared laser along the width direction of the electrode surface to heat it as radiant heat.

[0018] Preferably, the wavelength of the infrared laser irradiated by the pre-heater may be in a range that has an absorption rate of at least 10% for copper or aluminum, which is the material of the electrode, and an absorption rate of at least 70% or more for the electrode active material.

[0019] For example, the wavelength of the infrared laser may be within the range of 1,064±100 nm.

[0020] And, the output of the infrared laser can be controlled to an output per unit time that varies depending on the transport speed of the electrode so that the temperature of the electrode active material is in the range of 80±5°C.

[0021] According to the roll press device of the present invention having the above-described configuration, the electrode surface is heated by the infrared laser irradiated by the pre-heater. That is, the electrode is heated in the form of radiation heat conduction rather than conductive heat transfer.

[0022] Therefore, according to the roll press device of the present invention, the heating response speed is high due to radiant heat, the pre-heater is immediately cooled without residual heat when the power supply is cut off, and it is easy to increase the running speed of the electrode roll due to rapid heat transfer.

[0023] In addition, since the radiant heat selectively heats the electrode active material rather than the metal electrode, problems such as wrinkles due to expansion of the non-conductive region without the electrode active material do not occur.

[0024] However, the technical effects that can be obtained through the present invention are not limited to the above-described effects, and other effects that are not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0025] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0026] FIG. 1 is a schematic drawing of a roll press device according to one embodiment of the present invention.

[0027] Figure 2 is a graph showing the infrared absorption rate by wavelength for copper and aluminum.

[0028] Figure 3 is a schematic diagram illustrating the infrared absorption pattern in an electrode coated with an electrode active material.

[0029] Figure 4 is a drawing illustrating an example of irradiating an infrared laser onto an electrode surface coated with an electrode active material.

[0030] Figure 5 is a flowchart for a hot rolling method for a secondary battery electrode.

[0031] The present invention can be modified in various ways and has many embodiments, and specific embodiments will be described in detail below.

[0032] However, this is not intended to limit the present invention to a specific embodiment, but should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention.

[0033] In the present invention, it should be understood that terms such as “include” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0034] Additionally, in the present invention, when a part such as a layer, film, region, or plate is described as being "on" another part, this includes not only cases where it is "directly above" the other part, but also cases where there is another part in between. Conversely, when a part such as a layer, film, region, or plate is described as being "under" another part, this includes not only cases where it is "directly below" the other part, but also cases where there is another part in between. Furthermore, in the present application, "being placed on" may include cases where it is placed below as well as above.

[0035]

[0036] The present invention relates to a roll press device that performs hot rolling on an electrode coated with an electrode active material, and in one example, a pre-heater is arranged upstream of a rolling unit that performs rolling on an electrode transported in a roll-to-roll manner, and the pre-heater heats the electrode surface by radiating an infrared laser along the width direction thereof.

[0037] According to the roll press device of the present invention having the above-described configuration, the electrode surface is heated by the infrared laser irradiated by the pre-heater. That is, the electrode is heated in the form of radiation heat conduction rather than conductive heat transfer.

[0038] Therefore, according to the roll press device of the present invention, the heating response speed is high due to radiant heat, the pre-heater is immediately cooled without residual heat when the power supply is cut off, and it is easy to increase the running speed of the electrode roll due to rapid heat transfer.

[0039] Hereinafter, a specific embodiment of a roll press device (10) according to the present invention will be described in detail with reference to the attached drawings. For reference, the directions of front / back, up / down / left / right, etc., used to designate relative positions in the following description are intended to aid understanding of the invention, and unless otherwise specifically defined, the directions depicted in the drawings are taken as a reference.

[0040]

[0041] [First Embodiment]

[0042] FIG. 1 is a schematic drawing of a roll press device (10) according to one embodiment of the present invention.

[0043] The roll press device (10) refers to equipment that performs a rolling process to increase the density of the active material (310) by applying pressure to the surface of the electrode (300) to which the electrode active material (310) is applied, thereby making the thickness of the active material (310) constant. For the rolling process performed in a roll-to-roll manner, the electrode (300) to which the electrode active material (310) is applied is wound on a bobbin, and the bobbin on which the electrode (300) is wound is mounted on an unwinder (100). The electrode (300) mounted on the unwinder (100) is wound, and the wound electrode (300) is rewound in a downstream rewinder (140) and returned to a roll shape. An appropriate tension is applied to the electrode (300) transported in the roll-to-roll manner, thereby preventing various problems such as the electrode (300) sagging or waviness.

[0044] A rolling unit (120) is arranged between the unwinder (100) and the rewinder (140). The rolling unit (120) applies a set pressure to the electrode (300) as it passes between a pair of rotating rollers. The active material (310) of the electrode (300) that has received pressure increases in density and also becomes uniform in thickness. In addition, the roll press device (10) has an infeed (110) and an outfeed (130). The infeed (110) is arranged between the unwinder (100) and the rolling unit (120), and the outfeed (130) is arranged between the rolling unit (120) and the rewinder (140). The infeed (110) and the outfeed (130) serve to adjust the tension applied to the electrode (300) so that the electrode (300) can be smoothly transported, or to align the electrode (300). For example, the phenomenon of the electrode (300) traveling obliquely can be corrected by the infeed (110) and the outfeed (130).

[0045] The roll press device (10) of the present invention is equipped with a pre-heater (200) for performing hot rolling. Hot rolling raises the temperature of the electrode (300) to lower the surface hardness, thereby realizing a high rolling density with a small pressing force. Therefore, the pre-heater (200) is placed upstream of the rolling unit (120) that performs rolling on the electrode (300) transported in a roll-to-roll manner. By appropriately heating the electrode (300) by the pre-heater (200), hot rolling is performed in the rolling unit (120).

[0046] In the roll press device (10) of the present invention, the pre-heater (200) irradiates an infrared laser along the width direction of the surface of the electrode (300) being transported to heat it as radiant heat. The heating of the electrode (300) by the infrared is selectively absorbed by the electrode (300) made of a metal material and the electrode active material (310) applied thereon. In other words, the infrared shows a significant difference in absorption rate for the electrode (300) and the electrode active material (310).

[0047] Fig. 2 is a graph showing the absorption rate of copper and aluminum by infrared wavelength. Copper and aluminum are representative materials for electrodes (300) (anode and cathode), and as shown in Fig. 2, copper or aluminum has an absorption rate of at least 10% or less for infrared light. On the other hand, the electrode active material (310) that is close to black has an absorption rate of at least 70% or more for infrared light. Therefore, when an infrared laser of the same output is irradiated along the width direction of the surface of the electrode (300), the temperature of the electrode active material (310) rises significantly more than that of the electrode (300) due to the significant difference in absorption rate.

[0048] For example, the wavelength of an infrared laser may be within the range of 1,064±100 nm. In this wavelength range, the absorption rate of copper is less than about 1% and the absorption rate of aluminum is less than about 5%. On the other hand, the absorption rate of the electrode active material (310) is approximately 80% or more. That is, at the reference wavelength of 1,064 nm, the electrode active material (310) absorbs most of the infrared rays, and copper and aluminum reflect almost all of the infrared rays.

[0049] Fig. 3 is a schematic diagram illustrating the infrared absorption pattern in an electrode (300) to which an electrode active material (310) is applied. An electrode active material (310) is applied to the surface of the electrode (300), and a laser irradiator (210) provided in a pre-heater (200) irradiates an infrared laser. The infrared laser is first irradiated to the electrode active material (310) on the surface, and thus, some infrared light is reflected from the surface, but most infrared energy is absorbed by the electrode active material (310). In addition, some infrared light reaches the surface of the electrode (300), but most of it is reflected from the surface of the electrode (300) and reabsorbed into the electrode active material (310).

[0050] In this way, when the electrode (300) is heated by the radiant heat of an infrared laser, most of the energy is absorbed by the electrode active material (310), and only a very small portion is absorbed by the electrode (300) made of copper or aluminum. Heating by radiant heat has a fast response, and when the infrared irradiation is stopped, energy transfer is immediately cut off, and the selective heating by infrared radiation does not significantly increase the temperature of the electrode (300). Therefore, since the temperature rise of the electrode (300) on which the electrode active material (310) is not applied is significantly lower than when conventional conductive heat is applied, problems such as wrinkles in the uncoated region (320) due to expansion of the electrode (300) are also simultaneously resolved.

[0051] Fig. 4 is a drawing illustrating an example of irradiating an infrared laser onto the surface of an electrode (300) on which an electrode active material (310) is applied. In the embodiment illustrated exemplarily in Fig. 4, the pre-heater (200) is equipped with two laser irradiators (210). Each laser irradiator (210) irradiates infrared rays in a wavelength range of 1,064±100 nm, and can irradiate the infrared laser in a line beam or square beam manner across the transport direction of the electrode (300) transported in a roll-to-roll manner.

[0052] In addition, the operation of the laser irradiator (210) is controlled by the pre-heater controller (220). The pre-heater controller (220) can also adjust the output of the laser light. By adjusting the output of the infrared laser, the heating temperature for heating the electrode (300) can be adjusted. For example, the output of the infrared laser can be controlled to an output such that the temperature of the electrode active material (310) is within the range of 80±5°C.

[0053] For feedback control, a temperature sensor (230) for measuring the temperature of the electrode active material (310) may be placed downstream of the pre-heater (200). The temperature sensor (230) may, for example, measure the temperature of the electrode active material (310) in a non-contact manner. Based on the measured temperature of the electrode active material (310), the output of the infrared laser may be variably adjusted.

[0054] In addition, since the pre-heater (200) heats the electrode (300) that is transported in a roll-to-roll manner, it is preferable that the output of the infrared laser vary depending on the transport speed of the electrode (300). In other words, since the time for radiant heat to be transferred varies depending on the transport speed, it is appropriate to consider the transport speed of the electrode (300) when controlling the output of the laser. Accordingly, the output of the infrared laser can be controlled as an output per unit time that varies depending on the transport speed of the electrode (300).

[0055] Accordingly, when the transport speed of the electrode (300) is increased, the temperature of the electrode active material (310) can be increased to a required value, for example, in the range of 80±5°C, by irradiating the infrared laser with a higher output per unit time. This is made possible by the high responsiveness of the radiant heat and the immediate output control of the laser irradiator (210). In other words, the roll-to-roll transport speed can be increased within the range in which the output per unit time of the infrared laser is allowed. Therefore, the roll press device (10) of the present invention is advantageous in reducing the tact time by increasing the travel speed of the roll.

[0056]

[0057] [Second Embodiment]

[0058] Meanwhile, the present invention provides a method for hot rolling an electrode for a secondary battery, in which an electrode (300) coated with an electrode active material (310) is transported in a roll-to-roll manner, and a pre-heater (200) disposed upstream of a rolling unit (120) that performs rolling on the electrode (300) irradiates an infrared laser along the width direction of the surface of the electrode (300) to heat it as radiant heat. The main components of this method for hot rolling an electrode for a secondary battery are summarized in the flowchart of Fig. 5.

[0059] As described in the first embodiment, it may be preferable that the wavelength of the infrared laser irradiated by the pre-heater (200) be in a range that has an absorption rate of at least 10% for copper or aluminum, which is the material of the electrode (300), and an absorption rate of at least 70% or more for the electrode active material (310).

[0060] For example, the wavelength of the infrared laser irradiated by the pre-heater (200) may be within the range of 1,064±100 nm.

[0061] In addition, the output of the infrared laser can be controlled to an output per unit time that varies depending on the transport speed of the electrode (300) so that the temperature of the electrode active material (310) is within the range of 80±5°C. As described above, for feedback control, a temperature sensor (230) for measuring the temperature of the electrode active material (310) can be placed downstream of the pre-heater (200).

[0062]

[0063] The present invention has been described in more detail through drawings and examples. However, the configurations described in the drawings or examples described in this specification are merely embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as of the time of this application.

[0064]

[0065] [Explanation of symbols]

[0066] 10: Roll press device

[0067] 100: Unwinder

[0068] 110: Infeed

[0069] 120: Rolling unit

[0070] 130: Outfeed

[0071] 140: Rewinder

[0072] 200: Free hitter

[0073] 210: Laser irradiator

[0074] 220: Preheater controller

[0075] 230: Temperature sensor

[0076] 300: Electrode

[0077] 310: Electrode active material

[0078] 320: Ministry of Immigration

Claims

1. In a roll press device that performs hot rolling on an electrode to which an electrode active material is applied, A pre-heater is placed upstream of the rolling unit that performs rolling on the electrode transported in a roll-to-roll manner. The above pre-heater is a roll press device that heats as radiant heat by irradiating an infrared laser along the width direction of the electrode surface.

2. In paragraph 1, The wavelength of the infrared laser irradiated by the above pre-heater is A roll press device characterized in that it has an absorption rate of at least 10% for copper or aluminum, which is the material of the electrode, and an absorption rate of at least 70% or higher for the electrode active material.

3. In paragraph 2, The wavelength of the above infrared laser is, Roll press device within the range of 1,064±100㎚.

4. In paragraph 3, The output of the above infrared laser is: A roll press device controlled by an output so that the temperature of the electrode active material is in the range of 80±5℃.

5. In paragraph 4, The output of the above infrared laser is: A roll press device controlled by an output per unit time that varies according to the conveying speed of the above electrode.

6. In paragraph 1, The above pre-heater is, A roll press device that irradiates the infrared laser in a line beam or square beam manner across the transport direction of the electrode transported in a roll-to-roll manner.

7. The electrode coated with the electrode active material is transported in a roll-to-roll manner, A hot rolling method for an electrode for a secondary battery, wherein a pre-heater disposed upstream of a rolling unit that performs rolling on the electrode irradiates an infrared laser along the width direction of the surface of the electrode to heat it as radiant heat.

8. In paragraph 7, The wavelength of the infrared laser irradiated by the above pre-heater is A method for hot rolling an electrode for a secondary battery, characterized in that the electrode has an absorption rate of at least 10% for copper or aluminum, which is the material of the electrode, and an absorption rate of at least 70% or higher for the electrode active material.

9. In paragraph 8, The wavelength of the above infrared laser is, A method for hot rolling an electrode for a secondary battery, within the range of 1,064±100㎚.

10. In paragraph 9, The output of the above infrared laser is: A method for hot rolling an electrode for a secondary battery, wherein the output per unit time is controlled to vary depending on the transport speed of the electrode so that the temperature of the electrode active material is in the range of 80±5℃.

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